Articoli di riviste sul tema "Pako"
Segui questo link per vedere altri tipi di pubblicazioni sul tema: Pako.
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 articoli di riviste per l'attività di ricerca sul tema "Pako".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi gli articoli di riviste di molte aree scientifiche e compila una bibliografia corretta.
1
Pandey, Pramod Kumar, Ramkrishna Samanta e Raj Narain Singh Yadav. "Plant Beneficial Endophytic Bacteria from the Ethnomedicinal Mussaenda roxburghii (Akshap) of Eastern Himalayan Province, India". Advances in Biology 2015 (23 novembre 2015): 1–8. http://dx.doi.org/10.1155/2015/580510.
Testo completoAbstract (sommario):
Mussaenda roxburghii are very important ethnomedicinal plant, used for its various applications from the ancient period. The role of their associated plant beneficial endophytic bacteria was evaluated, which were previously untapped. Among the isolates, PAK6 was identified as efficient phosphate solubilizer, quantified by the molybdenum blue method. Four isolates PAK1, PAK2, PAK3, and PAK8 were able to synthesize significant level of IAA in the presence and absence of tryptophan. Isolates PAK1 and PAK9 were able to produce siderophore on CAS agar media, PAK2 and PAK9 were able to produce HCN, and PAK7 and PAK8 were able to grow on N2-free medium. All the isolates were able to produce a moderate level of polysaccharide and tolerate up to 10% of NaCl. Isolates PAK3, PAK6, PAK7, and PAK8 were able to grow well at pH 5.0 and isolates PAK2, PAK7, and PAK8 were able to tolerate 600 μg mL−1 of Al+3, while all the isolates except PAK1 showed a tolerance to 600 μg mL−1 of Mn+2 tested. Endophytic bacterial isolates PAK6 and PAK9 were effective against Sclerotinia sclerotiorum and Sclerotium rolfsii.
2
Rantala, Pälvi, e Leena-Maija Rossi. "Pako pohjoiseen ja pohjoisesta". Lähikuva – audiovisuaalisen kulttuurin tieteellinen julkaisu 33, n. 2 (16 agosto 2020): 8–24. http://dx.doi.org/10.23994/lk.97381.
Testo completoAbstract (sommario):
Vuonna 2015 Eurooppaan pyrki Lähi-idästä ja Pohjois-Afrikasta historiallisen suuri joukko turvapaikanhakijoita, pakolaisia ja siirtolaisia. Osa heistä päätyi suuntaamaan Suomeen Pohjois-Ruotsin ja Venäjän rajojen yli. Lapin sodan aikaan, vuonna 1944, pakolaisvirta kulki toiseen suuntaan: Suomesta Ruotsiin. Artikkeli tarkastelee taideteosta, jossa rinnastetaan nämä kaksi aikatasoa ja tapahtumakulkua.Minna Rainion ja Mark Robertsin lyhytelokuva They Came in Crowded Boats and Trains (2017 Suomi) kuvaa ”pohjoista” osin uudesta näkökulmasta. Elokuvan päähenkilöt, reaalielämässään itse turvapaikanhakijoita, ovat lukuisten mediaesitysten kehyksessä tunnistettavasti ”eteläisiä” hahmoja pohjoisessa maisemassa. Teoksen kertojaääni taas lukee otteita pohjoissuomalaisten pakolaisten kirjeistä ja päiväkirjoista seitsemänkymmenen vuoden takaa.Teoksessa menneisyyden ja nykyisyyden tapahtumat asettuvat ajan ja paikan ylittävään dialogiin. Kysymme artikkelissa, millainen kulttuurinen muisti ja kuvasto on rakentunut evakkouden ympärille ja miten Rainion ja Robertsin teos asettuu suhteessa siihen. Onko kahden aikakauden pakolaiskuvien välillä löydettävissä samanlaisuutta tai eroja? Analysoimme teoksessa rakentuvia suhteita ja asetelmia, kuten eri ajassa matkaavien pakolaisten eroja, erilaisuutta ja vertaisuutta, mutta myös elokuvassa rakentuvaa tietoisuutta suhteessa pakolaisuutta määrittäviin valtarakenteisiin ja historiallisiin rinnastuksiin.Escape from the North and to the North: Two Temporal Levels of Exile in the short film They Came in Crowded Boats and TrainsIn 2015 a historically vast number of refugees, asylum seekers and immigrants strived towards Europe from the Middle East and North Africa. Some of them ended up arriving in Finland, crossing the borders from either Northern Sweden or Russia. During the Lapland War, in 1944, the stream of refugees went to the opposite direction: from Finland to Sweden. In our article, we discuss a work of art, which draws a parallel between these two temporal levels and historical events. Minna Rainio and Mark Roberts’s short film They Came in Crowded Boats and Trains (2017 Finland) describes “the North” partly from a new perspective. The protagonists of the film, asylum seekers in their personal life, are in the framework of countless media representations recognizable as “southern” figures in a northern landscape. The voiceover in the film, however, reads excerpts from letters and diaries of northern Finnish refugees or evacuees from 70 years ago.In the film the events of past and present are situated in a dialogue, which transgresses both time and place. In the article we ask what kind of cultural memory and imagery has been constructed around being evacuated in 1944, and how Rainio and Roberts’ film situates itself in connection with this memory and imagery. How are the refugees represented in the film, and what kinds of similarities and differences are there to be found between the refugee representations of the two different eras? What kinds of associations, insights, and maybe even objections or criticisms the film evokes? Our article analyzes relations constructed in the narration: differences and similarities represented between refugees traveling in different times, but also the consciousness built in the film in relation to existing power structures and historical parallels defining what it means to be a refugee.
3
Sumantri, Hariyadi, Martinus Tukiran e Sufrin Hannan. "Using Technology Acceptance Model (TAM Model) to Increase Effectiveness the Use of Human Resource Information System (HRIS)". Jurnal Manajemen 14, n. 3 (5 ottobre 2023): 344–63. http://dx.doi.org/10.32832/jm-uika.v14i3.14492.
Testo completoAbstract (sommario):
Studies related to HRIS Applications show that the Technology Acceptance Model can be used to increase the use of HRIS Applications in a company. This research aims to test and reveal empirical factors that influence using the HRIS-Pakoku Application in the Pako Group. The two direct factors are perceived ease of use and perceived usefulness, and the indirect factor is a behavioural intention to use. This research was conducted at Pako Group using a questionnaire survey method, and samples were taken using the proposed stratified random sampling technique of 138 employees using HRIS at Pako Group. SEM analysis is used to determine the influence between research variables. The research results show a positive and significant influence of perceived ease of use on actual system use, a positive and significant influence of perceived usefulness on actual system use, and a positive and significant influence of behavioural intention to use on actual system use. There is a positive and insignificant influence of perceived ease of use on actual use through intention to use behaviour, and there is a positive and insignificant influence of perceived usefulness on actual system use through intention to use behaviour.
4
Noori, Mohammad Asif, Nasir Ahmad Sarwary e Sayed Ibrahim Farkhary. "Evaluation of the Physicochemical Properties of Different Imported Milk Brands Offered in Afghanistan Markets". Journal of Natural Science Review 2, n. 1 (8 aprile 2024): 57–67. http://dx.doi.org/10.62810/jnsr.v2i1.41.
Testo completoAbstract (sommario):
Milk is an enriched food that humans widely consume. It is the source of many nutrients like protein, fat, carbohydrates, vitamins, and minerals. The content of high-quality milk should match that of natural milk and national and international standards. In the current study, the quality of selected imported milk brands (Pak1, Pak2, Pak3, Pak4, and Ir1) and local cow milk in the markets of Kabul City was evaluated. For this purpose, the levels of protein, fat, total solid, solid not fat, acidity, pH, and specific gravity were measured. Data analysis was conducted using the Kruskal-Wallis test in GraphPad Prism software. Our findings showed that the protein level in imported brands was significantly lower than the standard of cow milk (p<0.01). Among imported brands, the protein level in Ir1 and Pak4 was higher than other brands and the standard (p<0.05). The level of fat in Pak2 and Pak3 was higher than the standard and other brands (p<0.05), the level of total solid in Ir1 was lower than the standard (p<0.05), and the level of solid not fat in Pak2 and Pak3 was lower than the standard (p<0.05). Our results showed that local cow milk has a higher quality than imported milk brands, and among the brands, Pak4 has a higher quality than other brands, where its quality is almost the same as the composition of local cow milk.
5
Maude, George. "Lackman, Matti. Sotavankien pako. Muurmanin ratatyömaalta 1915â1918 (review)". Slavonic and East European Review 92, n. 1 (gennaio 2014): 157–59. http://dx.doi.org/10.1353/see.2014.0128.
Testo completo
6
McCarty, Samantha K., Motoyasu Saji, Xiaoli Zhang, David Jarjoura, Alfredo Fusco, Vasyl V. Vasko e Matthew D. Ringel. "Group I p21-activated kinases regulate thyroid cancer cell migration and are overexpressed and activated in thyroid cancer invasion". Endocrine-Related Cancer 17, n. 4 (dicembre 2010): 989–99. http://dx.doi.org/10.1677/erc-10-0168.
Testo completoAbstract (sommario):
p21-activated kinases (PAKs) are a family of serine/threonine kinases that regulate cytoskeletal dynamics and cell motility. PAKs are subdivided into group I (PAKs 1–3) and group II (PAKs 4–6) on the basis of structural and functional characteristics. Based on prior gene expression data that predicted enhanced PAK signaling in the invasive fronts of aggressive papillary thyroid cancers (PTCs), we hypothesized that PAKs functionally regulate thyroid cancer cell motility and are activated in PTC invasive fronts. We examined PAK isoform expression in six human thyroid cancer cell lines (BCPAP, KTC1, TPC1, FTC133, C643, and SW1746) by quantitative reverse transcription-PCR and western blot. All cell lines expressed PAKs 1–4 and PAK6 mRNA and PAKs 1–4 protein; PAK6 protein was variably expressed. Samples from normal and malignant thyroid tissues also expressed PAKs 1–4 and PAK6 mRNA; transfection with the group I (PAKs 1–3) PAK-specific p21 inhibitory domain molecular inhibitor reduced transwell filter migration by ∼50% without altering viability in all cell lines (P<0.05). BCPAP and FTC133 cells were transfected with PAK1, PAK2, or PAK3-specific small interfering RNA (siRNA); only PAK1 siRNA reduced migration significantly for both cell lines. Immunohistochemical analysis of seven invasive PTCs demonstrated an increase in PAK1 and pPAK immunoactivity in the invasive fronts versus the tumor center. In conclusion, PAK isoforms are expressed in human thyroid tissues and cell lines. PAK1 regulates thyroid cancer cell motility, and PAK1 and pPAK levels are increased in PTC invasive fronts. These data implicate PAKs as regulators of thyroid cancer invasion.
7
Dechert, Melissa A., Jennifer M. Holder e William T. Gerthoffer. "p21-activated kinase 1 participates in tracheal smooth muscle cell migration by signaling to p38 MAPK". American Journal of Physiology-Cell Physiology 281, n. 1 (1 luglio 2001): C123—C132. http://dx.doi.org/10.1152/ajpcell.2001.281.1.c123.
Testo completoAbstract (sommario):
Cell migration contributes to many physiological processes and requires dynamic changes in the cytoskeleton. These migration-dependent cytoskeletal changes are partly mediated by p21-activated protein kinases (PAKs). At least four closely related isoforms, PAK1, PAK2, PAK3, and PAK4, exist in mammalian cells. In smooth muscle cells, little is known about the expression, activation, or ability of PAKs to regulate migration. Our study revealed the existence of three PAK isoforms in cultured tracheal smooth muscle cells (TSMCs). Additionally, we constructed adenoviral vectors encoding wild type and a catalytically inactive PAK1 mutant to investigate PAK activation and its role in TSMC migration. Stimulation of TSMCs with platelet-derived growth factor (PDGF) increased the activity of PAK1 over time. Overexpression of mutant PAK1 blocked PDGF-induced chemotactic cell migration. Phosphorylation of p38 mitogen-activated protein kinase (MAPK) in cells overexpressing wild-type PAK1 was similar to vector controls; however, p38 MAPK phosphorylation was severely reduced by overexpression of the PAK1 mutant. Collectively, these results suggest a role for PAK1 in chemotactic TSMC migration that involves catalytic activity and may require signaling to p38 MAPK among other pathways.
8
Wells, Claire M., e Gareth E. Jones. "The emerging importance of group II PAKs". Biochemical Journal 425, n. 3 (15 gennaio 2010): 465–73. http://dx.doi.org/10.1042/bj20091173.
Testo completoAbstract (sommario):
The Rho-family GTPases Rho Rac and Cdc42 regulate many intracellular processes through their interaction with downstream effector proteins. The PAKs (p21-activated kinases) are a family of effector proteins for Rac and Cdc42. PAKs are important regulators of actin cytoskeletal dynamics, neurite outgrowth, cell survival, hormone signalling and gene transcription. There are six mammalian PAKs that can be divided into two groups: group I PAKs (PAK1–3) and group II PAKs (PAK4–6). Although the two PAK groups are architecturally similar, there are differences in their mode of regulation, suggesting that their cellular functions are likely to be different. Whereas much is known about group I PAKs, less is known about the more recently discovered PAK4, PAK5 and PAK6. This review will focus on the latest structural and functional results relating to the group II PAKs and discuss the emerging importance of group II PAKs in disease progression.
9
Torres, Annabel, Alice Tang, Radha Vyas, Chen Su, Matthew Johnson e Andrew Wells. "PAK6- A novel kinase in the maintenance of T cell anergy". Journal of Immunology 202, n. 1_Supplement (1 maggio 2019): 184.8. http://dx.doi.org/10.4049/jimmunol.202.supp.184.8.
Testo completoAbstract (sommario):
Abstract Costimulation of T cells through the antigen receptor and the CD28 receptor engages an ‘effector’ gene expression program and a burst of proliferation. Conversely, antigen receptor engagement in the absence of costimulation induces a hypo-responsive state, referred to as anergy, that is associated with active silencing of effector genes. Our ATAC-seq analysis of CD28-dependent chromatin remodeling in anergic and effector CD4+ T cells has identified p21-activated kinase 6 (PAK6) as a gene that becomes accessible in anergic but not effector T cells. PAK6 is a member of a family of kinases comprised of two groups, group I (PAK1-3) and group II (PAK4-6). PAK6 and other group II members lack a regulatory domain that is present in group I, causing it to function differently. Previous studies by others have shown that PAK2, a group I PAK, was a positive regulator of CD3/CD28 T cell activation. Here, we demonstrate that PAK6 has the opposite role in T cell activation as PAK2, where it inhibits IL2 secretion, a hallmark characteristic of T cell anergy. Knockdown of PAK6 in anergic and effector T cells, using a CRISPR/CAS9 approach, resulted in a 50% increase in IL2 secretion, and 5-fold more cell expansion in anergic cultures upon restimulation with CD3/CD28. This suggests that PAK6 may be involved in a signaling pathway which inhibits cellular proliferation or promotes apoptosis. The highest level of PAK6 expression was observed upon re-stimulation of anergic cells, suggesting that PAK6 may be involved in the maintenance of T cell anergy. This study identifies a novel role for PAK6 in T cell anergy and a potential new target for regulating T cell function in autoimmune diseases.
10
Eswaran, Jeyanthy, Wen Hwa Lee, Judit É. Debreczeni, Panagis Filippakopoulos, Andrew Turnbull, Oleg Fedorov, Sean W. Deacon, Jeffrey R. Peterson e Stefan Knapp. "Crystal Structures of the p21-Activated Kinases PAK4, PAK5, and PAK6 Reveal Catalytic Domain Plasticity of Active Group II PAKs". Structure 15, n. 2 (febbraio 2007): 201–13. http://dx.doi.org/10.1016/j.str.2007.01.001.
Testo completo
11
White, Joyce C. "And through Flows the River: Archaeology and the Pasts of Lao Pako (review)". Asian Perspectives 45, n. 1 (2006): 102–4. http://dx.doi.org/10.1353/asi.2006.0016.
Testo completo
12
Wang, Jiaxi, Caleb A. Lareau, Jhoanne L. Bautista, Im Hong Sun, Alexander R. Gupta e James M. Gardner. "Single-cell multiomics defines tolerogenic extrathymic Aire-expressing cells with unique homology to thymic epithelium". Journal of Immunology 208, n. 1_Supplement (1 maggio 2022): 54.01. http://dx.doi.org/10.4049/jimmunol.208.supp.54.01.
Testo completoAbstract (sommario):
Abstract The autoimmune regulator (Aire) protein, a key transcriptional regulator expressed in medullary thymic epithelial cells (mTECs), is crucial for central tolerance. Aire is also found in extrathymic Aire-expressing cells (eTACs) in secondary lymphoid organs. eTACs are hematopoietic antigen-presenting cells that are capable of inducing immune tolerance, but the precise identity of eTACs has remained unclear. To define eTACs, we utilized a combination of single-cell multiomics, transgenic murine models, and functional approaches. We found that eTACs consist of two similar cell types: CCR7+ Aire-expressing migratory dendritic cells and an Aire-high population co-expressing Aire and retinoic acid receptor–related orphan receptor γt (RORγt) that we termed Janus cells (JCs). eTACs, particularly JCs, have highly accessible chromatin and share remarkable homology with mTECs. Additionally, transgenic self-antigen expression by eTACs is sufficient to induce negative selection of cognate autoreactive T cells and prevent autoimmune diabetes. To better define the function of extrathymic Aire in eTACs and its contribution to peripheral immune tolerance, we have generated a Peripheral Aire KnockOut (PAKO) mouse (Vav1-Cre x Aire-fl/fl). Using intracellular Aire staining by flow cytometry, we validated that PAKO mice lack all eTACs in secondary lymphoid organs while maintaining normal thymic Aire expression in mTECs. Studying the biology of eTACs and peripheral Aire will help further elucidate the function of Aire and define basic peripheral tolerance mechanisms, which may have significance for a range of clinical applications from autoimmunity to tumor immunity to maternal-fetal tolerance. Supported by ARCS Foundation
13
Vargas, Benni, James Boslett, Nathan Yates e Nicolas Sluis-Cremer. "Mechanism by Which PF-3758309, a Pan Isoform Inhibitor of p21-Activated Kinases, Blocks Reactivation of HIV-1 Latency". Biomolecules 13, n. 1 (4 gennaio 2023): 100. http://dx.doi.org/10.3390/biom13010100.
Testo completoAbstract (sommario):
The “block and lock” strategy is one approach that might elicit a sterilizing cure for HIV-1 infection. The “block” refers to a compound’s ability to inhibit latent HIV-1 proviral transcription, while the “lock” refers to its capacity to induce permanent proviral silencing. We previously identified PF-3758309, a pan-isoform inhibitor of p21-activated kinases (PAKs), as a potent inhibitor of HIV-1 latency reversal. The goal of this study was to define the mechanism(s) involved. We found that both 24ST1NLESG cells (a cell line model of HIV-1 latency) and purified CD4+ naïve and central memory T cells express high levels of PAK2 and lower levels of PAK1 and PAK4. Knockdown of PAK1 or PAK2, but not PAK4, in 24ST1NLESG cells resulted in a modest, but statistically significant, decrease in the magnitude of HIV-1 latency reversal. Overexpression of PAK1 significantly increased the magnitude of latency reversal. A phospho-protein array analysis revealed that PF-3758309 down-regulates the NF-κB signaling pathway, which provides the most likely mechanism by which PF-3758309 inhibits latency reversal. Finally, we used cellular thermal shift assays combined with liquid chromatography and mass spectrometry to ascertain whether PF-3758309 off-target binding contributed to its activity. In 24ST1NLESG cells and in peripheral blood mononuclear cells, PF-3758309 bound to mitogen-activated protein kinase 1 and protein kinase A; however, knockdown of either of these kinases did not impact HIV-1 latency reversal. Collectively, our study suggests that PAK1 and PAK2 play a key role in the maintenance of HIV-1 latency.
14
Knietsch, Anja, Susanne Bowien, Gregg Whited, Gerhard Gottschalk e Rolf Daniel. "Identification and Characterization of Coenzyme B12-Dependent Glycerol Dehydratase- and Diol Dehydratase-Encoding Genes from Metagenomic DNA Libraries Derived from Enrichment Cultures". Applied and Environmental Microbiology 69, n. 6 (giugno 2003): 3048–60. http://dx.doi.org/10.1128/aem.69.6.3048-3060.2003.
Testo completoAbstract (sommario):
ABSTRACT To isolate genes encoding coenzyme B12-dependent glycerol and diol dehydratases, metagenomic libraries from three different environmental samples were constructed after allowing growth of the dehydratase-containing microorganisms present for 48 h with glycerol under anaerobic conditions. The libraries were searched for the targeted genes by an activity screen, which was based on complementation of a constructed dehydratase-negative Escherichia coli strain. In this way, two positive E. coli clones out of 560,000 tested clones were obtained. In addition, screening was performed by colony hybridization with dehydratase-specific DNA fragments as probes. The screening of 158,000 E. coli clones by this method yielded five positive clones. Two of the plasmids (pAK6 and pAK8) recovered from the seven positive clones contained genes identical to those encoding the glycerol dehydratase of Citrobacter freundii and were not studied further. The remaining five plasmids (pAK2 to -5 and pAK7) contained two complete and three incomplete dehydratase-encoding gene regions, which were similar to the corresponding regions of enteric bacteria. Three (pAK2, -3, and -7) coded for glycerol dehydratases and two (pAK4 and -5) coded for diol dehydratases. We were able to perform high-level production and purification of three of these dehydratases. The glycerol dehydratases purified from E. coli Bl21/pAK2.1 and E. coli Bl21/pAK7.1 and the complemented hybrid diol dehydratase purified from E. coli Bl21/pAK5.1 were subject to suicide inactivation by glycerol and were cross-reactivated by the reactivation factor (DhaFG) for the glycerol dehydratase of C. freundii. The activities of the three environmentally derived dehydratases and that of glycerol dehydratase of C. freundii with glycerol or 1,2-propanediol as the substrate were inhibited in the presence of the glycerol fermentation product 1,3-propanediol. Taking the catalytic efficiency, stability against inactivation by glycerol, and inhibition by 1,3-propanediol into account, the hybrid diol dehydratase produced by E. coli Bl21/pAK5.1 exhibited the best properties of all tested enzymes for application in the biotechnological production of 1,3-propanediol.
15
Nitta, Eiji. "Lao Pako--A Late Prehistoric Site on the Nam Ngum River in Laos (review)". Asian Perspectives 42, n. 1 (2003): 169–71. http://dx.doi.org/10.1353/asi.2003.0027.
Testo completo
16
Furnari, Melody A., Michelle L. Jobes, Tanya Nekrasova, Audrey Minden e George C. Wagner. "Functional Deficits in Pak5, Pak6 and Pak5/Pak6 Knockout Mice". PLoS ONE 8, n. 4 (8 aprile 2013): e61321. http://dx.doi.org/10.1371/journal.pone.0061321.
Testo completo
17
Nathania, Ivena. "Analisis Koreografi Tari Liuk Si Liri". Jurnal Seni Tari 10, n. 2 (29 novembre 2021): 120–31. http://dx.doi.org/10.15294/jst.v10i2.43397.
Testo completoAbstract (sommario):
Permasalahan yang dibahas dalam penelitian ini ialah bagaimana analisis koreografi karyatari Liuk Si Liri. Tujuan penulisan ini adalah untuk mengetahui lebih detail analisis koreografi tariLiuk Si Liri agar dapat menjadi informasi atau sumber acuan dalam menganalisis suatu gerak tari.Metode yang digunakan dalam penelitian ini adalah kualitatif. Teknik pengumpulan data meliputiobservasi, wawancara, dokumentasi serta studi pustaka. Dalam penelitian ini menggunakanmetodologi kualitatif yang dibantu dengan metodologi penelitian deskriptif pustaka. Penelitianmenunjukkan bahwa bahwa koreografer mengangkat tema dengan latar belakang perempuan SukuDayak Kayaan Mendalam yang berfokus pada tato motif Tedak pako’ yang digunakan sehinggamenjadi keunikan bagi perempuan Suku Dayak Kayaan Mendalam dengan skema dramatik akhirkerucut tunggal yang ditambah instrument musik Ketabung, Kanong satu, Kanong dua, Gong,Tetawak, Kacapi Rabab dan Piano yang mampu menambah unsur dramatik karya
18
Filipović, Adrijana, Irena Vujević, Stanko Ivanković, Radica Ćorić, Dragan Jurković e Višnja Vasilj. "THE EFFECT OF SOIL SELENIUM FERTILIZATION TREATMENT ON THE CONTENT OF SOME IONS (Cd, Fe, Zn and Se) AND YIELD OF TWO CORN HYBRIDS". Radovi Šumarskog fakulteta Univerziteta u Sarajevu 21, n. 1 (1 ottobre 2016): 179–90. http://dx.doi.org/10.54652/rsf.2016.v1.i1.294.
Testo completoAbstract (sommario):
UDK 631.8(497.6 Čapljina)
The concentration and form of some metals and metalloids in soil is governed by many chemical and physical properties of soil as pH, redox, Fe, Al ions and soil composition. The paper studied presents influence of chemical soil properties, environment conditions and selenium fertilization rate applied on ions status of zinc, cadmium, selenium and iron in soil and plant material, as well as specific adsorption of these ions in two different maize hybrids. The study was conducted at the farm Vita-Vi Višići (Čapljina). The experiment design was a completely randomized design with two hybrids, four different fertilization treatments in four replications. The experimental area was implemented standard agricultural management practices of preparation, tillage, fertilization, application of protective agents. Hybrid NP Pako is selected in order to achieve a high yield, and M34 hybrid for quality yield. The test results and statistical analysis revealed no significant difference in the yield of hybrids combined with different fertilization treatments. Accumulation of selenium, zinc, cadmium and iron in upper ground plant part of maize was not affected by fertilization treatments or selected hybrid. The highest yield was achieved by hybrid M34 Pioneer of 37.6 t ha- 1and the highest yield was obtained in application of third fertilization treatment 20 kg NaSeO4ha-1, but without statistically significant differences comparing to other hybrid or applied treatments. The highest content of selenium in the plant was found in hybrid NP PAKO 0.06 mg Se kg-1 of dry matter of maize applying the fourth liquid fertilization treatment (20 kg Na2SeO4ha-1) but also without statistically significant difference comparing to other hybrid or fertilization treatment. Content of zinc, cadmium and iron in soil or plant material had not shown significant differences due to the applied fertilization or used maize hybrids, but some fluctuations were observed. Selenium fertilization did not have a limiting effect on the formation of the yield and tested elements, but its mobility and availability in soil and plant depends also on other factors as soil properties and climatic conditions of growing season.
19
Coniglio, Salvatore J., Salvatore Zavarella e Marc H. Symons. "Pak1 and Pak2 Mediate Tumor Cell Invasion through Distinct Signaling Mechanisms". Molecular and Cellular Biology 28, n. 12 (14 aprile 2008): 4162–72. http://dx.doi.org/10.1128/mcb.01532-07.
Testo completoAbstract (sommario):
ABSTRACT Pak kinases are thought to play critical roles in cell migration and invasion. Here, we analyze the roles of Pak1 and Pak2 in breast carcinoma cell invasion using the transient transfection of small interfering RNA. We find that although both Pak1 and Pak2 contribute to breast carcinoma invasion stimulated by heregulin, these roles are mediated by distinct signaling mechanisms. Thus, whereas the depletion of Pak1 interferes with the heregulin-mediated dephosphorylation of cofilin, the depletion of Pak2 does not. The depletion of Pak1 also has a stronger inhibitory effect on lamellipodial protrusion than does the depletion of Pak2. Interestingly, Pak1 and Pak2 play opposite roles in regulating the phosphorylation of the myosin light chain (MLC). Whereas the depletion of Pak1 decreases phospho-MLC levels in heregulin-stimulated cells, the depletion of Pak2 enhances MLC phosphorylation. Consistent with their opposite effects on MLC phosphorylation, Pak1 and Pak2 differentially modulate focal adhesions. Pak2-depleted cells display an increase in focal adhesion size, whereas in Pak1-depleted cells, focal adhesions fail to mature. We also found that the depletion of Pak2, but not Pak1, enhances RhoA activity and that the inhibition of RhoA signaling in Pak2-depleted cells decreases MLC phosphorylation and restores cell invasion. In summary, this work presents the first comprehensive analysis of functional differences between the Pak1 and Pak2 isoforms.
20
Rupasov, A. I. "Рецензия на монографию: Lackman M. Sotavankien pako. Muurmannin ratatyömaalta 1915-1918. Saarijärvi: Soumalaisen Kirjallisuuden Seura, 2012. 357 s". Петербургский исторический журнал, n. 1 (2014): 262. http://dx.doi.org/10.51255/2311-603x-2014-00019.
Testo completo
21
Nguyen, Deborah G., Karen C. Wolff, Hong Yin, Jeremy S. Caldwell e Kelli L. Kuhen. "“UnPAKing” Human Immunodeficiency Virus (HIV) Replication: Using Small Interfering RNA Screening To Identify Novel Cofactors and Elucidate the Role of Group I PAKs in HIV Infection". Journal of Virology 80, n. 1 (1 gennaio 2006): 130–37. http://dx.doi.org/10.1128/jvi.80.1.130-137.2006.
Testo completoAbstract (sommario):
ABSTRACT In order to identify novel proviral host factors involved in human immunodeficiency virus (HIV) infection, we performed a screen of a small interfering RNA (siRNA) library targeting 5,000 genes with the highest potential for being targets for therapeutics. Many siRNAs in the library against known host factors, such as TSG101, furin, and CXCR4, were identified as inhibitors by the screen and thus served as internal validation. In addition, many novel factors whose knockdown inhibited infection were identified, including Pak3, a member of the serine/threonine group I PAK kinases. The HIV accessory factor Nef has been shown to associate with a PAK kinase, leading to enhanced viral production; however, the exact identity of the kinase has remained controversial. Prompted by the Pak3 screen hit, we further investigated the involvement of group I PAK kinases in HIV using siRNA. Contrary to the current literature, Pak1 depletion strongly inhibited HIV infection in multiple cell systems and decreased levels of integrated provirus, while Pak2 depletion showed no effect. Overexpression of a constitutively active Pak1 mutant also enhanced HIV infection, further supporting its role as the dominant PAK involved.
22
Dan, Chuntao, Niharika Nath, Muriel Liberto e Audrey Minden. "PAK5, a New Brain-Specific Kinase, Promotes Neurite Outgrowth in N1E-115 Cells". Molecular and Cellular Biology 22, n. 2 (15 gennaio 2002): 567–77. http://dx.doi.org/10.1128/mcb.22.2.567-577.2002.
Testo completoAbstract (sommario):
ABSTRACT We have characterized a new member of the mammalian PAK family of serine/threonine kinases, PAK5, which is a novel target of the Rho GTPases Cdc42 and Rac. The kinase domain and GTPase-binding domain (GBD) of PAK5 are most closely related in sequence to those of mammalian PAK4. Outside of these domains, however, PAK5 is completely different in sequence from any known mammalian proteins. PAK5 does share considerable sequence homology with the Drosophila MBT protein (for “mushroom body tiny”), however, which is thought to play a role in development of cells in Drosophila brain. Interestingly, PAK5 is highly expressed in mammalian brain and is not expressed in most other tissues. We have found that PAK5, like Cdc42, promotes the induction of filopodia. In N1E-115 neuroblastoma cells, expression of PAK5 also triggered the induction of neurite-like processes, and a dominant-negative PAK5 mutant inhibited neurite outgrowth. Expression of activated PAK1 caused no noticeable changes in these cells. An activated mutant of PAK5 had an even more dramatic effect than wild-type PAK5, indicating that the morphologic changes induced by PAK5 are directly related to its kinase activity. Although PAK5 activates the JNK pathway, dominant-negative JNK did not inhibit neurite outgrowth. In contrast, the induction of neurites by PAK5 was abolished by expression of activated RhoA. Previous work has shown that Cdc42 and Rac promote neurite outgrowth by a pathway that is antagonistic to Rho. Our results suggest, therefore, that PAK5 operates downstream to Cdc42 and Rac and antagonizes Rho in the pathway, leading to neurite development.
23
Hawley, Eric, Jeffrey Gehlhausen, Sofiia Karchugina, Hoi-Yee Chow, Daniela Araiza-Olivera, Maria Radu, Abbi Smith et al. "PAK1 inhibition reduces tumor size and extends the lifespan of mice in a genetically engineered mouse model of Neurofibromatosis Type 2 (NF2)". Human Molecular Genetics 30, n. 17 (1 giugno 2021): 1607–17. http://dx.doi.org/10.1093/hmg/ddab106.
Testo completoAbstract (sommario):
Abstract Neurofibromatosis Type II (NF2) is an autosomal dominant cancer predisposition syndrome in which germline haploinsufficiency at the NF2 gene confers a greatly increased propensity for tumor development arising from tissues of neural crest derived origin. NF2 encodes the tumor suppressor, Merlin, and its biochemical function is incompletely understood. One well-established function of Merlin is as a negative regulator of group A serine/threonine p21-activated kinases (PAKs). In these studies we explore the role of PAK1 and its closely related paralog, PAK2, both pharmacologically and genetically, in Merlin-deficient Schwann cells and in a genetically engineered mouse model (GEMM) that develops spontaneous vestibular and spinal schwannomas. We demonstrate that PAK1 and PAK2 are both hyper activated in Merlin-deficient murine schwannomas. In preclinical trials, a pan Group A PAK inhibitor, FRAX-1036, transiently reduced PAK1 and PAK2 phosphorylation in vitro, but had insignificant efficacy in vivo. NVS-PAK1-1, a PAK1 selective inhibitor, had a greater but still minimal effect on our GEMM phenotype. However, genetic ablation of Pak1 but not Pak2 reduced tumor formation in our NF2 GEMM. Moreover, germline genetic deletion of Pak1 was well tolerated, while conditional deletion of Pak2 in Schwann cells resulted in significant morbidity and mortality. These data support the further development of PAK1-specific small molecule inhibitors and the therapeutic targeting of PAK1 in vestibular schwannomas and argue against PAK1 and PAK2 existing as functionally redundant protein isoforms in Schwann cells.
24
Weisz Hubsman, Monika, Natalia Volinsky, Edward Manser, Deborah Yablonski e Ami Aronheim. "Autophosphorylation-dependent degradation of Pak1, triggered by the Rho-family GTPase, Chp". Biochemical Journal 404, n. 3 (29 maggio 2007): 487–97. http://dx.doi.org/10.1042/bj20061696.
Testo completoAbstract (sommario):
The Paks (p21-activated kinases) Pak1, Pak2 and Pak3 are among the most studied effectors of the Rho-family GTPases, Rac, Cdc42 (cell division cycle 42) and Chp (Cdc42 homologous protein). Pak kinases influence a variety of cellular functions, but the process of Pak down-regulation, following activation, is poorly understood. In the present study, we describe for the first time a negative-inhibitory loop generated by the small Rho-GTPases Cdc42 and Chp, resulting in Pak1 inhibition. Upon overexpression of Chp, we unexpectedly observed a T-cell migration phenotype consistent with Paks inhibition. In line with this observation, overexpression of either Chp or Cdc42 caused a marked reduction in the level of Pak1 protein in a number of different cell lines. Chp-induced degradation was accompanied by ubiquitination of Pak1, and was dependent on the proteasome. The susceptibility of Pak1 to Chp-induced degradation depended on its p21-binding domain, kinase activity and a number of Pak1 autophosphorylation sites, whereas the PIX- (Pak-interacting exchange factor) and Nck-binding sites were not required. Together, these results implicate Chp-induced kinase autophosphorylation in the degradation of Pak1. The N-terminal domain of Chp was found to be required for Chp-induced degradation, although not for Pak1 activation, suggesting that Chp provides a second function, distinct from kinase activation, to trigger Pak degradation. Collectively, our results demonstrate a novel mechanism of signal termination mediated by the Rho-family GTPases Chp and Cdc42, which results in ubiquitin-mediated degradation of one of their direct effectors, Pak1.
25
Kořánová, Tereza, Lukáš Dvořáček, Dana Grebeňová, Pavla Röselová, Adam Obr e Kateřina Kuželová. "PAK1 and PAK2 in cell metabolism regulation". Journal of Cellular Biochemistry 123, n. 2 (8 novembre 2021): 375–89. http://dx.doi.org/10.1002/jcb.30175.
Testo completo
26
Li, Xiaofan, e Audrey Minden. "Targeted Disruption of the Gene for the PAK5 Kinase in Mice". Molecular and Cellular Biology 23, n. 20 (15 ottobre 2003): 7134–42. http://dx.doi.org/10.1128/mcb.23.20.7134-7142.2003.
Testo completoAbstract (sommario):
ABSTRACT PAK5 is a member of the group B family of PAK serine/threonine kinases and is an effector for the Rho GTPase Cdc42. PAK5 is highly expressed in the brain and is expressed at lower levels in several other tissues. In cell lines, PAK5 has been shown to play a role in filopodia formation and neurite outgrowth. To examine the biological function of PAK5, we deleted the PAK5 gene in mice. The phenotypes of the PAK5-null mice are completely different from those of mice null for PAK4, another member of the group B PAK family. Unlike PAK4-null mice, which are embryonic lethal, PAK5-null mice develop normally and are fertile. The nervous system appears normal in the absence of PAK5, as do other tissues in which PAK5 is normally expressed. Our results suggest functional redundancy between PAK5 and other Rho GTPase targets.
27
Arora, Vivek K., Rene P. Molina, John L. Foster, John L. Blakemore, Jonathan Chernoff, Brenda L. Fredericksen e J. Victor Garcia. "Lentivirus Nef Specifically Activates Pak2". Journal of Virology 74, n. 23 (1 dicembre 2000): 11081–87. http://dx.doi.org/10.1128/jvi.74.23.11081-11087.2000.
Testo completoAbstract (sommario):
ABSTRACT Nef proteins from human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) have been found to associate with an active cellular serine/threonine kinase designated Nef-associated kinase (Nak). The exact identity of Nak remains controversial, with two recent studies indicating that Nak may be either Pak1 or Pak2. In this study, we investigated the hypothesis that such discrepancies arise from the use of different Nef alleles or different cell types by individual investigators. We first confirm that Pak2 but not Pak1 is cleaved by caspase 3 in vitro and then demonstrate that Nak is caspase 3 sensitive, regardless of Nef allele or cell type used. We testednef alleles from three lentiviruses (HIV-1 SF2, HIV-1 NL4-3, and SIVmac239) and used multiple cell lines of myeloid, lymphoid, and nonhematopoietic origin to evaluate the identity of Nak. We demonstrate that ectopically expressed Pak2 can substitute for Nak, while ectopically expressed Pak1 cannot. We then show that Nef specifically mediates the robust activation of ectopically expressed Pak2, directly demonstrating that Nef regulates Pak2 activity and does not merely associate with activated Pak2. We report that most of the active Pak2 is found bound to Nef, although a fraction is not. In contrast, only a small amount of Nef is found associated with Pak2. We conclude that Nak is Pak2 and that Nef specifically mediates Pak2 activation in a low-abundance complex. These results will facilitate both the elucidation of the role of Nef in pathogenesis and the development of specific inhibitors of this highly conserved function of Nef.
28
Edlinger, Leo, Angelika Berger-Becvar, Ingeborg Menzl, Gregor Hoermann, Georg Greiner, Eva Grundschober, Zsuzsanna Bago-Horvath et al. "Expansion ofBCR/ABL1+cells requires PAK2 but not PAK1". British Journal of Haematology 179, n. 2 (14 luglio 2017): 229–41. http://dx.doi.org/10.1111/bjh.14833.
Testo completo
29
Renkema, G. Herma, Aki Manninen e Kalle Saksela. "Human Immunodeficiency Virus Type 1 Nef Selectively Associates with a Catalytically Active Subpopulation of p21-Activated Kinase 2 (PAK2) Independently of PAK2 Binding to Nck or β-PIX". Journal of Virology 75, n. 5 (1 marzo 2001): 2154–60. http://dx.doi.org/10.1128/jvi.75.5.2154-2160.2001.
Testo completoAbstract (sommario):
ABSTRACT We have recently identified the Nef-associated serine-threonine kinase (NAK) as the p21-activated kinase 2 (PAK2). Here we have taken advantage of the possibility to manipulate the functional properties of NAK by transfecting PAK2 cDNA or its mutant derivatives in order to further characterize the Nef-NAK complex. To exclude the possibility that some Nef variants might interact with PAK1 instead of PAK2, we also examined the identity of NAK complexed with divergent human immunodeficiency virus type 1 HIV-1 Nef proteins. All tested Nef proteins, including SF2, NL4-3, BH10, and HAN-2, associated with PAK2 but not with PAK1. By exchanging different regions between these two PAK proteins, the selective ability of PAK2 to associate with Nef could be mapped to the carboxy-terminal part of its regulatory domain. Binding of PAK2 with the adapter protein Nck or β-PIX was found to be dispensable for the assembly of the Nef-PAK2 complex, whereas an intact Cdc42-Rac1 interactive binding motif was required. Most importantly, we found that NAK represented a distinct subpopulation of the total cellular PAK2 characterized by a high specific kinase activity. Thus, although only a small fraction of cellular PAK2 could be found in complex with Nef, NAK represented a major part of cellular PAK2 activity.
30
Cai, Qingqing, Ning Su, Yu Fang, Xu Chen, Xiaopeng Tian, Shuyun Ma, Xiaoqin Chen et al. "The Expression of Paks and Its Clinical Significance in T-Cell Lymphoblastic Lymphoma". Blood 136, Supplement 1 (5 novembre 2020): 14–16. http://dx.doi.org/10.1182/blood-2020-136975.
Testo completoAbstract (sommario):
Background: T-cell lymphoblastic lymphoma (T-LBL) is a highly aggressive non-Hodgkin's lymphoma with poor prognosis and lacks of standard treatment approaches. PAK2, a member of the p21 activated kinase (PAKs) family, is a component of the gene-expression-based classifier which made great contributions to prognostic prediction of T-LBL(Cai et al. Leukemia 2020). This study aims to analyze the expression of PAKs in human T-LBL cell lines and tissues to clarify its clinical significance and evaluate the therapeutic activity of PAKs inhibitor in T-LBL. Methods: The mRNA and protein expression levels of PAKs in human T-lymphoid cell lines (H9) and T-LBL cell lines (Jurkat, SUP-T1 and CCRF-CEM) were detected by quantitative real-time PCR and western blot, respectively. We retrospectively collected 69 Formalin-fixed, Paraffin-embedded (FFPE) samples and corresponding clinical information from T -LBL patients between September 2000 and May 2015 at Sun Yat-sen University Cancer Center (SYSUCC). Affymetrix Human Gene 2.0 ST microarray (Thermo Fisher Scientific, Waltham, MA, USA) was used to detect the expression of PAKs. Mann-Whitney U test was used for comparing the expression differences between relapsed and non-relapsed patients. Cumulative relapse-free survival (RFS) time was calculated using the Kaplan-Meier method (Expression level higher than the upper quartile (P75) was defined as PAK1 or PAK 2 high expression. High expression (median as cutoff point) of both PAK1 and PAK2 was defined as PAK1/2 high expression). Pearson's chi-square test and Fisher's exact test were used to compare the distribution of clinical variables. Correlations between PAK1, PAK2 and NOTCH1 were evaluated using Spearman's correlation coefficient. Two PAK inhibitors, PF3758309 (PF) and FRAX597, were used to block PAK kinase activity pharmacologically. Cell viability was determined using the viability assay kit CCK-8. Cell cycle and cell apoptosis were analyzed by flow cytometry. All statistical analyses were performed using SPSS 24.0 software (SPSS, Armonk, NY, USA) or GraphPad Prism 8.0 (GraphPad, La Jolla, CA, USA). A P value < 0.05 was considered significant. The study protocol was approved by the Institutional Review Board of SYSUCC. Results: The mRNA and protein expression levels of PAK1 in T-LBL cell lines of Jurkat, SUP-T1 and CCRF-CEM cell lines were significantly higher than those in T-lymphoid cell lines H9 cell line (P<0.05) (Figure 1). Of the 69 T-LBL patients, 44 (63.8%) were male and the median age at diagnosis was 30 years (range: 16-44). The majority (72.5%) of the patients received acute lymphoblastic leukemia (ALL)-type chemotherapy regimens. The PAK2 mRNA expression level of 32 patients with relapsed disease was significantly higher than that of 37 cases without relapse (P=0.012), and no difference was found in mRNA expression of PAK1, 3, 4, 7(Figure 2). Patients with high PAK1 and PAK2 expression had significantly shorter median RFS than those with low PAK1 and PAK2 expression (PAK1 mRFS 31.5 months vs not reached(NR), HR=3.001, P=0.028; PAK2 mRFS 25.7 months vs NR, HR=3.981, P=0.027)(Figure 3). Patients with high PAK1/2 mRNA expression experienced earlier relapse than patients with low PAK1/2 mRNA expression (mRFS 26.0 months vs NR, HR=2.721, P=0.032)(Figure 3). PAK1/2 mRNA expression was found to be associated with hemoglobin concentration, Ki-67 expression, pleural and pericardia effusion, bone marrow involvement and chemotherapy response (P<0.05)(Table 1). Further, the PAK1 mRNA was correlated with the expression of NOTCH1, which is frequently mutated in T-LBL (r=0.5716, P<0.0001)(Figure 4). The PAK inhibitors PF and FRAX597 demonstrated strong anti-tumor activity in vitro (Table 2). Both inhibitors suppressed cell proliferation in a time- and dose-dependent manner (Figure 5). Both inhibitors induced cell cycle arrest in the G1/0 phase, accompanied by corresponding S phase reductions in all tested cells(Figure 6). The synergistic effect between PAK inhibitor PF and doxorubicin was also observed (Figure 7). Besides, PF could inhibit the phosphorylation of PAK1/2, Cyclin D1 and NF-κB in Jurkat cell line(Figure 8). Conclusions: PAK1 and PAK2 play certain roles in the occurrence and recurrence of T-LBL, and their potential as novel biomarkers deserves further exploring. Our results underscore the potential of PAK inhibitor as effective target therapy for T-LBL. Disclosures No relevant conflicts of interest to declare.
31
Tabanifar, Bahareh, Zhuoshen Zhao e Ed Manser. "PAK5 is auto-activated by a central domain that promotes kinase oligomerization". Biochemical Journal 473, n. 12 (10 giugno 2016): 1777–89. http://dx.doi.org/10.1042/bcj20160132.
Testo completoAbstract (sommario):
The present study shows for the first time that self-association of PAK5 in vivo underlies its high basal activity, which contrasts with the inactive state of cellular PAK4. Such PAK5 self-association interferes with the engagement of the auto-inhibitory (AID) with the catalytic domain.
32
Zhu, Jianxin, Ortal Attias, Lamine Aoudjit, Ruihua Jiang, Hiroshi Kawachi e Tomoko Takano. "p21-Activated kinases regulate actin remodeling in glomerular podocytes". American Journal of Physiology-Renal Physiology 298, n. 4 (aprile 2010): F951—F961. http://dx.doi.org/10.1152/ajprenal.00536.2009.
Testo completoAbstract (sommario):
The tyrosine phosphorylation of nephrin is reported to regulate podocyte morphology via the Nck adaptor proteins. The Pak family of kinases are regulators of the actin cytoskeleton and are recruited to the plasma membrane via Nck. Here, we investigated the role of Pak in podocyte morphology. Pak1/2 were expressed in cultured podocytes. In mouse podocytes, Pak2 was predominantly phosphorylated, concentrated at the tips of the cellular processes, and its expression and/or phosphorylation were further increased when differentiated. Overexpression of rat nephrin in podocytes increased Pak1/2 phosphorylation, which was abolished when the Nck binding sites were mutated. Furthermore, dominant-negative Nck constructs blocked the Pak1 phosphorylation induced by antibody-mediated cross linking of nephrin. Transient transfection of constitutively kinase-active Pak1 into differentiated mouse podocytes decreased stress fibers, increased cortical F-actin, and extended the cellular processes, whereas kinase-dead mutant, kinase inhibitory construct, and Pak2 knockdown by shRNA had the opposite effect. In a rat model of puromycin aminonucleoside nephrosis, Pak1/2 phosphorylation was decreased in glomeruli, concomitantly with a decrease of nephrin tyrosine phosphorylation. These results suggest that Pak contributes to remodeling of the actin cytoskeleton in podocytes. Disturbed nephrin-Nck-Pak interaction may contribute to abnormal morphology of podocytes and proteinuria.
33
Wang, Kai, Graham S. Baldwin, Mehrdad Nikfarjam e Hong He. "Antitumor effects of all-trans retinoic acid and its synergism with gemcitabine are associated with downregulation of p21-activated kinases in pancreatic cancer". American Journal of Physiology-Gastrointestinal and Liver Physiology 316, n. 5 (1 maggio 2019): G632—G640. http://dx.doi.org/10.1152/ajpgi.00344.2018.
Testo completoAbstract (sommario):
Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal malignancies worldwide. All-trans retinoic acid (ATRA) has been used as an antistromal agent in PDA, and its antitumor effect has also been reported in various kinds of cancer, including PDA. Inhibition of p21-activated kinases (PAKs) is associated with decreased tumor growth and increased gemcitabine sensitivity. The aim of this study was to evaluate the inhibitory effects of ATRA alone and in combination with gemcitabine on cell growth and migration of wild-type and gemcitabine-resistant PDA cells and the potential mechanism(s) involved. Human (MiaPaCa-2) and murine (TB33117) PDA cell lines were incubated in increasing concentrations of gemcitabine to establish resistant clones. Cell growth, clonogenicity, and migration/invasion were determined using a sulforhodamine B assay, a colony formation assay, and a Boyden chamber assay, respectively. Protein expression was measured by Western blotting. ATRA reduced cell proliferation, colony formation, and migration/invasion in both wild-type and gemcitabine-resistant cell lines. PAK1 expression was significantly increased in resistant cells. Cells treated with ATRA showed decreased expression of PAK1, PAK2, PAK4, and α-smooth muscle actin. The combination of ATRA and gemcitabine synergistically reduced cell growth in both wild-type and gemcitabine-resistant cell lines. Depletion of PAK1 enhanced ATRA sensitivity in MiaPaCa-2 cells. In conclusion, the antitumor effects of ATRA and its synergism with gemcitabine are associated with downregulation of PAKs.NEW & NOTEWORTHY The inhibitory effect of all-trans retinoic acid (ATRA) on cell proliferation, colony formation, and migration/invasion was associated with downregulation of p21-activated kinases (PAKs), and depletion of PAK1 enhanced ATRA sensitivity in MiaPaCa-2 cells. The combination of ATRA and gemcitabine synergistically reduced cell growth in both wild-type and gemcitabine-resistant pancreatic ductal adenocarcinoma cells. As an important prognostic marker, α-smooth muscle actin also can be downregulated by ATRA in pancreatic ductal adenocarcinoma cells.
34
Combeau, Gaëlle, Patricia Kreis, Florence Domenichini, Muriel Amar, Philippe Fossier, Véronique Rousseau e Jean-Vianney Barnier. "The p21-activated Kinase PAK3 Forms Heterodimers with PAK1 in Brain Implementing Trans-regulation of PAK3 Activity". Journal of Biological Chemistry 287, n. 36 (19 luglio 2012): 30084–96. http://dx.doi.org/10.1074/jbc.m112.355073.
Testo completo
35
Yi, Liang, Haifeng Wang, Xiguang Deng, Haifan Yuan, Dong Xu e Huiqiang Yao. "Geochronology and Geochemical Properties of Mid-Pleistocene Sediments on the Caiwei Guyot in the Northwest Pacific Imply a Surface-to-Deep Linkage". Journal of Marine Science and Engineering 9, n. 3 (27 febbraio 2021): 253. http://dx.doi.org/10.3390/jmse9030253.
Testo completoAbstract (sommario):
Seamounts are ubiquitous topographic units in the global ocean, and their effects on local circulation have attracted great research attention in physical oceanography; however, fewer relevant efforts were made on geological timescales in previous studies. The Caiwei (Pako) Guyot in the Magellan Seamounts of the western Pacific is a typical seamount and oceanographic characteristics have been well documented. In this study, we investigate a sediment core by geochronological and geochemical studies to reveal a topography-induce surface-to-bottom linkage. The principal results are as follows: (1) Two magnetozones are recognized in core MABC–11, which can be correlated to the Brunhes and Matuyama chrons; (2) Elements Ca, Si, Cl, K, Mn, Ti, and Fe are seven elements with high intensities by geochemical scanning; (3) Ca intensity can be tuned to global ice volume to refine the age model on glacial-interglacial timescales; (4) The averaged sediment accumulation rate is ~0.73 mm/kyr, agreeing with the estimate of the excess 230Th data in the upper part. Based on these results, a proxy of element Mn is derived, whose variability can be correlated with changes in global ice volume and deep-water masses on glacial-interglacial timescales. This record is also characterized by an evident 23-kyr cycle, highlighting a direct influence of solar insolation on deep-sea sedimentary processes. Overall, sedimentary archives of the Caiwei Guyot not only record an intensified abyssal ventilation during interglaciations in the western Pacific, but also provide a unique window for investigating the topography-induced linkage between the upper and bottom ocean on orbital timescales.
36
Kaczmarczyk, Andreas, Ramon Hochstrasser, Julia A. Vorholt e Anne Francez-Charlot. "Two-Tiered Histidine Kinase Pathway Involved in Heat Shock and Salt Sensing in the General Stress Response of Sphingomonas melonis Fr1". Journal of Bacteriology 197, n. 8 (9 febbraio 2015): 1466–77. http://dx.doi.org/10.1128/jb.00019-15.
Testo completoAbstract (sommario):
ABSTRACTThe general stress response (GSR) allows bacteria to monitor and defend against a broad set of unrelated, adverse environmental conditions. InAlphaproteobacteria, the key step in GSR activation is phosphorylation of the response regulator PhyR. InSphingomonas melonisFr1, seven PhyR-activating kinases (Paks), PakA to PakG, are thought to directly phosphorylate PhyR under different stress conditions, but the nature of the activating signals remains obscure. PakF, a major sensor of NaCl and heat shock, lacks a putative sensor domain but instead harbors a single receiver (REC) domain (PakFREC) N-terminal to its kinase catalytic core. Such kinases are called “hybrid response regulators” (HRRs). How HRRs are able to perceive signals in the absence of a true sensor domain has remained largely unexplored. In the present work, we show that stresses are actually sensed by another kinase, KipF (kinase of PakF), which phosphorylates PakFRECand thereby activates PakF. KipF is a predicted transmembrane kinase, harboring a periplasmic CHASE3 domain flanked by two transmembrane helices in addition to its cytoplasmic kinase catalytic core. We demonstrate that KipF senses different salts through its CHASE3 domain but is not a sensor of general osmotic stress. While salt sensing depends on the CHASE3 domain, heat shock sensing does not, suggesting that these stresses are perceived by different mechanisms. In summary, our results establish a two-tiered histidine kinase pathway involved in activation of the GSR inS. melonisFr1 and provide the first experimental evidence for the so far uncharacterized CHASE3 domain as a salt sensor.IMPORTANCEHybrid response regulators (HRRs) represent a particular class of histidine kinases harboring an N-terminal receiver (REC) domain instead of a true sensor domain. This suggests that the actual input for HRRs may be phosphorylation of the REC domain. In the present study, we addressed this question by using the HRR PakF. Our results suggest that PakF is activated through phosphorylation of its REC domain and that this is achieved by another kinase, KipF. KipF senses heat shock and salt stress, with the latter requiring the periplasmic CHASE3 domain. This work not only suggests that HRRs work in two-tiered histidine kinase pathways but also provides the first experimental evidence for a role of the so far uncharacterized CHASE3 domain in salt sensing.
37
Bright, Michael D., Andrew P. Garner e Anne J. Ridley. "PAK1 and PAK2 have different roles in HGF-induced morphological responses". Cellular Signalling 21, n. 12 (dicembre 2009): 1738–47. http://dx.doi.org/10.1016/j.cellsig.2009.07.005.
Testo completo
38
Boda, Bernadett, Lorena Jourdain e Dominique Muller. "Distinct, but compensatory roles of PAK1 and PAK3 in spine morphogenesis". Hippocampus 18, n. 9 (settembre 2008): 857–61. http://dx.doi.org/10.1002/hipo.20451.
Testo completo
39
Han, Di, Huiqun Wang, Wei Cui, Beibei Zhang e Bo-Zhen Chen. "Computational insight into the mechanisms of action and selectivity of Afraxis PAK inhibitors". Future Medicinal Chemistry 12, n. 5 (marzo 2020): 367–85. http://dx.doi.org/10.4155/fmc-2019-0273.
Testo completoAbstract (sommario):
Aim: The p21-activated kinases (PAKs) are involved in many important biological activity regulations. FRAX019, FRAX414, FRAX597, FRAX1036 and G-5555 were identified as PAKs inhibitors. Their detailed inhibitory mechanisms deserve further investigation. Results: Molecular dynamics simulations and further calculations for the PAK1/inhibitor and PAK4/inhibitor complexes indicate that their binding free energies are basically consistent with the trend of experimental activity data. Conclusion: The anchoring of residues Leu347PAK1 and Leu398PAK4 is the structural basis for designing Afraxis PAK inhibitors. This study discloses the inhibitory mechanisms of FRAX019, FRAX414, FRAX597, FRAX1036 and G-5555 toward PAK1 and PAK4 and some clues to enhance kinase activities and selectivities, which will provide valuable information to the development of more potent and selective PAK inhibitors.
40
Cotteret, Sophie, Zahara M. Jaffer, Alexander Beeser e Jonathan Chernoff. "p21-Activated Kinase 5 (Pak5) Localizes to Mitochondria and Inhibits Apoptosis by Phosphorylating BAD". Molecular and Cellular Biology 23, n. 16 (15 agosto 2003): 5526–39. http://dx.doi.org/10.1128/mcb.23.16.5526-5539.2003.
Testo completoAbstract (sommario):
ABSTRACT Pak5 is the most recently identified and least understood member of the p21-activated kinase (Pak) family. This kinase is known to promote neurite outgrowth in vitro, but its localization, substrates, and effects on cell survival have not been reported. We show here that Pak5 has unique properties that distinguish it from all other members of the Pak family. First, Pak5, unlike Pak1, cannot complement an STE20 mutation in Saccharomyces cerevisiae. Second, Pak5 binds to the GTPases Cdc42 and Rac, but these GTPases do not regulate Pak5 kinase activity, which is constitutive and stronger than any other Pak. Third, Pak5 prevents apoptosis induced by camptothecin and C2-ceramide by phosphorylating BAD on Ser-112 in a protein kinase A-independent manner and prevents the localization of BAD to mitochondria, thereby inhibiting the apoptotic cascade that leads to apoptosis. Finally, we show that Pak5 itself is constitutively localized to mitochondria, and that this localization is independent of kinase activity or Cdc42 binding. These features make Pak5 unique among the Pak family and suggest that it plays an important role in apoptosis through BAD phosphorylation.
41
UIBLEIN, FRANZ, e JØRGEN G. NIELSEN. "Five new ocellus-bearing species of the cusk-eel genus Neobythites (Ophidiidae, Ophidiiformes) from the West Pacific, with establishment of three new species groups". Zootaxa 5336, n. 2 (22 agosto 2023): 179–205. http://dx.doi.org/10.11646/zootaxa.5336.2.2.
Testo completoAbstract (sommario):
Five new West Pacific species of the cusk-eel genus Neobythites (Ophidiidae) from the lower shelf and upper slope of the Solomon Sea, off Okinawa, Japan, and off Fiji are described. The descriptions are based on nine specimens from three fish collections and unvouchered fresh colour photographs showing three specimens taken shortly after being caught. The new species all bear at least one ocellus on the dorsal fin, a conspicuous colour pattern consisting of a dark spot surrounded by a contrasting white or pale ring. Fifteen ocellus-bearing congeners are rather similar with at least one of the new species, requiring detailed comparisons based on a large set of morphometric, meristic, colour and otolith-shape data from over 300 specimens. To facilitate the comparisons among the 20 Neobythites species in total and the preparation of identification keys, three new taxonomic species groups, the australiensis, kenyaensis and longiventralis groups, are established. Also, the steatiticus species group which had been previously established, is slightly updated. A key for identification of each of these four groups is prepared. The most important characters for distinction among groups are the presence and number of preopercular spines, the number and position of ocelli, and pelvic-fin length. For each of the three new groups, species accounts including new species descriptions, within-group comparisons, and identification keys are prepared. For the steatiticus group, only the description of the new species, N. pako n. sp., and an updated account of the Atlantic N. monocellatus are provided, considering previously published accounts of the other seven species in comparisons with those two species and the identification key. The results are shortly discussed, emphasizing the finding of a unique ocellus structure in N. superocellatus n. sp. (australiensis species group) and the need for taxonomic studies of the remaining 10 ocellus-bearing species of Neobythites together with additional, non-ocellus-bearing congeners.
42
Radu, Maria, Sonali J. Rawat, Alexander Beeser, Anton Iliuk, Weiguo Andy Tao e Jonathan Chernoff. "ArhGAP15, a Rac-specific GTPase-activating Protein, Plays a Dual Role in Inhibiting Small GTPase Signaling". Journal of Biological Chemistry 288, n. 29 (11 giugno 2013): 21117–25. http://dx.doi.org/10.1074/jbc.m113.459719.
Testo completoAbstract (sommario):
Signaling from small GTPases is a tightly regulated process. In this work we used a protein microarray screen to identify the Rac-specific GAP, ArhGAP15, as a substrate of the Rac effectors Pak1 and Pak2. In addition to serving as a substrate of Pak1/2, we found that ArhGAP15, via its PH domain, bound to these kinases. The association of ArhGAP15 to Pak1/2 resulted in mutual inhibition of GAP and kinase catalytic activity, respectively. Knock-down of ArhGAP15 resulted in activation of Pak1/2, both indirectly, as a result of Rac activation, and directly, as a result of disruption of the ArhGAP15/Pak complex. Our data suggest that ArhGAP15 plays a dual negative role in regulating small GTPase signaling, by acting at the level of the GTPase itself, as well interacting with its effector, Pak kinase.
43
Radu, Maria, Karen Lyle, Klaus P. Hoeflich, Olga Villamar-Cruz, Hartmut Koeppen e Jonathan Chernoff. "p21-Activated Kinase 2 Regulates Endothelial Development and Function through the Bmk1/Erk5 Pathway". Molecular and Cellular Biology 35, n. 23 (21 settembre 2015): 3990–4005. http://dx.doi.org/10.1128/mcb.00630-15.
Testo completoAbstract (sommario):
p21-activated kinases (Paks) have been shown to regulate cytoskeleton rearrangements, cell proliferation, attachment, and migration in a variety of cellular contexts, including endothelial cells. However, the role of endothelial Pak in embryo development has not been reported, and currently, there is no consensus on the endothelial function of individual Pak isoforms, in particular p21-activated kinase 2 (Pak2), the main Pak isoform expressed in endothelial cells. In this work, we employ genetic and molecular studies that show that Pak2, but not Pak1, is a critical mediator of development and maintenance of endothelial cell function. Endothelial depletion of Pak2 leads to early embryo lethality due to flawed blood vessel formation in the embryo body and yolk sac. In adult endothelial cells, Pak2 depletion leads to severe apoptosis and acute angiogenesis defects, and in adult mice, endothelial Pak2 deletion leads to increased vascular permeability. Furthermore, ubiquitous Pak2 deletion is lethal in adult mice. We show that many of these defects are mediated through a newly unveiled Pak2/Bmk1 pathway. Our results demonstrate that endothelial Pak2 is essential during embryogenesis and also for adult blood vessel maintenance, and they also pinpoint the Bmk1/Erk5 pathway as a critical mediator of endothelial Pak2 signaling.
44
Itakura, Asako, Joseph E. Aslan, Branden T. Kusanto, Kevin G. Phillips, Robert H. Insall, Jonathan Chernoff e Owen J. T. McCarty. "p21-Activated Kinases Regulate Directional Migration and Cytoskeletal Organization in Human Neutrophils". Blood 120, n. 21 (16 novembre 2012): 834. http://dx.doi.org/10.1182/blood.v120.21.834.834.
Testo completoAbstract (sommario):
Abstract Abstract 834 Neutrophil chemotaxis is controlled by coordinated processes of directional sensing, polarization and motility. This study was designed to characterize the role of p21-activated kinases (PAKs) during the chemotaxis of human primary neutrophils. PAKs are known as effectors of the Rho GTPases Rac and Cdc42. It has been shown that PAK1 and PAK2 are strongly activated downstream of the f-Met-Leu-Phe (fMLP) receptor via Rac (Huang et al., MCB 1998). PAK1 is known to localize in lamellipodia at the leading edge of human neutrophils (Dharmawardhane et al., JLB 1999) and mediate persistent directional migration via Cdc42 in a neutrophil-like cell line (Li et al., Cell 2003). However, little is known about the specific role of PAK isoforms in spatial/temporal regulation of cytoskeletal dynamics in human neutrophils. Our data show that human neutrophils express PAK1, 2 and 4. Under an fMLP gradient, human neutrophils developed morphological polarity with a distinct leading edge and rear, and migrated up the fMLP gradient at the speed of 7.5 ± 0.56 μm/min. Inhibition of Rac or PI3K impaired directionality but did not significantly affect migration speed of chemotaxing neutrophils (6.3 ± 0.56 μm/min or 6.2 ± 0.85 μm/min, respectively). In contrast, neutrophils treated with the PAK inhibitor, PF3758309 (PF), displayed random migration, less polarization and reduced motility (3.1 ± 0.21 μm/min). These results suggest that PAK regulates neutrophil chemotaxis independently of the Rac-PI3K axis. The presence of PF did not abrogate intracellular Ca2+mobilization in fMLP-driven chemotactic condition. Instead, the decreased migratory ability by PAK inhibition was associated with multiple Ca2+ spikes. Immunofluorescence imaging shows that PAK2 but not PAK1, was phosphorylated and translocated from cytosol to actin-rich leading edge in the proximity to GTP-bound Rac within 3 min of fMLP stimulation. Notably, PF treatment resulted in partial neutrophil spreading and actin/myosin II translocation in the absence of extracellular stimuli, suggesting that basal level of PAK phosphorylation may be required for cytoskeletal integrity of resting neutrophils. Neutrophils pretreated with PF displayed less activation and translocation of PAK2 and Rac. In summary, our data demonstrate for the first time the distinct roles of PAK isoforms in human neutrophil morphological polarity and directional migration and suggest that PAK2 is activated downstream of fMLP receptor through Rho-family small GTPases. Disclosures: No relevant conflicts of interest to declare.
45
Zeng, Q., D. Lagunoff, R. Masaracchia, Z. Goeckeler, G. Cote e R. Wysolmerski. "Endothelial cell retraction is induced by PAK2 monophosphorylation of myosin II". Journal of Cell Science 113, n. 3 (1 febbraio 2000): 471–82. http://dx.doi.org/10.1242/jcs.113.3.471.
Testo completoAbstract (sommario):
The p21-activated kinase (PAK) family includes several enzyme isoforms regulated by the GTPases Rac1 and Cdc42. PAK1, found in brain, muscle and spleen, has been implicated in triggering cytoskeletal rearrangements such as the dissolution of stress fibers and reorganization of focal complexes. The role of the more widely distributed PAK2 in controlling the cytoskeleton has been less well studied. Previous work has demonstrated that PAK2 can monophosphorylate the myosin II regulatory light chain and induce retraction of permeabilized endothelial cells. In this report we characterize PAK2's morphological and biochemical effect on intact endothelial cells utilizing microinjection of constitutively active PAK2. Under these conditions we observed a modification of the actin cytoskeleton with retraction of endothelial cell margins accompanied by an increase in monophosphorylation of myosin II. Selective inhibitors were used to analyze the mechanism of action of PAK2. Staurosporine, a direct inhibitor of PAK2, largely prevented the action of microinjected PAK2 in endothelial cells. Butanedione monoxime, a non-specific myosin ATPase inhibitor, also inhibited the effects of PAK2 implicating myosin in the changes in cytoskeletal reorganization. In contrast, KT5926, a specific inhibitor of myosin light chain kinase was ineffective in preventing the changes in morphology and the actin cytoskeleton. The additional finding that endogenous PAK2 associates with myosin II is consistent with the proposal that cell retraction and cytoskeletal rearrangements induced by microinjected PAK2 depend on the direct activation of myosin II by PAK2 monophosphorylation of the regulatory light chain.
46
Zhang, Hongquan, Zhilun Li, Eva-Karin Viklund e Staffan Strömblad. "p21-activated kinase 4 interacts with integrin αvβ5 and regulates αvβ5-mediated cell migration". Journal of Cell Biology 158, n. 7 (23 settembre 2002): 1287–97. http://dx.doi.org/10.1083/jcb.200207008.
Testo completoAbstract (sommario):
p21-activated kinase 1 (PAK1) can affect cell migration (Price et al., 1998; del Pozo et al., 2000) and modulate myosin light chain kinase and LIM kinase, which are components of the cellular motility machinery (Edwards, D.C., L.C. Sanders, G.M. Bokoch, and G.N. Gill. 1999. Nature Cell Biol. 1:253–259; Sanders, L.C., F. Matsumura, G.M. Bokoch, and P. de Lanerolle. 1999. Science. 283:2083–2085). We here present a novel cell motility pathway by demonstrating that PAK4 directly interacts with an integrin intracellular domain and regulates carcinoma cell motility in an integrin-specific manner. Yeast two-hybrid screening identified PAK4 binding to the cytoplasmic domain of the integrin β5 subunit, an association that was also found in mammalian cells between endogenous PAK4 and integrin αvβ5. Furthermore, we mapped the PAK4 binding to the membrane-proximal region of integrin β5, and identified an integrin-binding domain at aa 505–530 in the COOH terminus of PAK4. Importantly, engagement of integrin αvβ5 by cell attachment to vitronectin led to a redistribution of PAK4 from the cytosol to dynamic lamellipodial structures where PAK4 colocalized with integrin αvβ5. Functionally, PAK4 induced integrin αvβ5–mediated, but not β1-mediated, human breast carcinoma cell migration, while no changes in integrin cell surface expression levels were observed. In conclusion, our results demonstrate that PAK4 interacts with integrin αvβ5 and selectively promotes integrin αvβ5–mediated cell migration.
47
Flis, Sylwia, Ewelina Bratek, Tomasz Chojnacki, Marlena Piskorek e Tomasz Skorski. "Simultaneous Inhibition of BCR-ABL1 Tyrosine Kinase and PAK1/2 Serine/Threonine Kinases Exerts Synergistic Effect Against Chronic Myeloid Leukemia Cells". Blood 134, Supplement_1 (13 novembre 2019): 4143. http://dx.doi.org/10.1182/blood-2019-129093.
Testo completoAbstract (sommario):
Tyrosine kinase inhibitors (TKIs) revolutionized the treatment of BCR-ABL1 tyrosine kinase - positive chronic myeloid leukemia in chronic phase (CML-CP). However, it is unlikely that TKIs will "cure" the disease in majority of patients because CML-CP cells are elusive targets even for the most advanced therapies employing second and third generation of TKIs. Therefore, new treatment modalities are necessary to improve therapeutic outcomes. We showed before that class I p21-activated serine/threonine kinases (PAKs) remained active in TKI-naive and TKI-treated CML-CP leukemia stem and early progenitor cells. The aim of the study was to test whether simultaneous inhibition of signaling pathways activated by BCR-ABL1 and PAK kinases may improve the treatment of CML. Special attention was focused on PAK1 and PAK2, which are expressed in hematopoietic cells and can play an important role in the promotion of CML cells proliferation and survival. PAK kinases were targeted by small molecule inhibitor IPA-3 (inhibitor of PAK1) and shRNA construct for PAK2, BCR-ABL1 kinase was inhibited by imatinib. The studies were carried out using (i) primary CML-CP stem/early progenitor cells and normal hematopoietic counterparts isolated from the bone marrow of newly diagnosed CML-CP patients and healthy donors, respectively, (ii) CML-blast phase cell lines (K562 and KCL-22), and (iii) BCR-ABL1-transformed 32Dcl3 cell line cells. We show here that inhibition of PAK1 or/and PAK2 kinases activity enhanced the effect of IM against CML cells without affecting normal counterparts. We observed that the combined use of IM with IPA-3 increased growth inhibition and apoptosis of leukemia cells. To evaluate the type of drugs interaction median effect analysis method was used. The studies revealed that the type and strength of drug interaction depend on drug concentration. Generally, combination of IM with IPA-3 at the 50% of the cell kill level (EC50) generated synergistic effect. Altogether, we postulate that BCR-ABL1 kinase inhibitor should be combined with PAK1/2 inhibitor to facilitate eradication of CML cells. Disclosures No relevant conflicts of interest to declare.
48
van Dijk, Juliette, Guillaume Bompard, Gabriel Rabeharivelo, Julien Cau, Claude Delsert e Nathalie Morin. "PAK1 Regulates MEC-17 Acetyltransferase Activity and Microtubule Acetylation during Proplatelet Extension". International Journal of Molecular Sciences 21, n. 20 (13 ottobre 2020): 7531. http://dx.doi.org/10.3390/ijms21207531.
Testo completoAbstract (sommario):
Mature megakaryocytes extend long processes called proplatelets from which platelets are released in the blood stream. The Rho GTPases Cdc42 and Rac as well as their downstream target, p21-activated kinase 2 (PAK2), have been demonstrated to be important for platelet formation. Here we address the role, during platelet formation, of PAK1, another target of the Rho GTPases. PAK1 decorates the bundled microtubules (MTs) of megakaryocyte proplatelets. Using a validated cell model which recapitulates proplatelet formation, elongation and platelet release, we show that lack of PAK1 activity increases the number of proplatelets but restrains their elongation. Moreover, in the absence of PAK1 activity, cells have hyperacetylated MTs and lose their MT network integrity. Using inhibitors of the tubulin deacetylase HDAC6, we demonstrate that abnormally high levels of MT acetylation are not sufficient to increase the number of proplatelets but cause loss of MT integrity. Taken together with our previous demonstration that MT acetylation is required for proplatelet formation, our data reveal that MT acetylation levels need to be tightly regulated during proplatelet formation. We identify PAK1 as a direct regulator of the MT acetylation levels during this process as we found that PAK1 phosphorylates the MT acetyltransferase MEC-17 and inhibits its activity.
49
Ramos-Álvarez, Irene, Lingaku Lee e Robert T. Jensen. "Group II p21-activated kinase, PAK4, is needed for activation of focal adhesion kinases, MAPK, GSK3, and β-catenin in rat pancreatic acinar cells". American Journal of Physiology-Gastrointestinal and Liver Physiology 318, n. 3 (1 marzo 2020): G490—G503. http://dx.doi.org/10.1152/ajpgi.00229.2019.
Testo completoAbstract (sommario):
PAK4 is the only member of the Group II p21-activated kinases (PAKs) present in rat pancreatic acinar cells and is activated by gastrointestinal hormones/neurotransmitters stimulating PLC/cAMP and by various pancreatic growth factors. However, little is known of the role of PAK4 activation in cellular signaling cascades in pancreatic acinar cells. In the present study, we examined the role of PAK4’s participation in five different cholecystokinin-8 (CCK-8)-stimulated signaling pathways (PI3K/Akt, MAPK, focal adhesion kinase, GSK3, and β-catenin), which mediate many of its physiological acinar-cell effects, as well as effects in pathophysiological conditions. To define PAK4’s role, the effect of two different PAK4 inhibitors, PF-3758309 and LCH-7749944, was examined under experimental conditions that only inhibited PAK4 activation and not activation of the other pancreatic PAK, Group I PAK2. The inhibitors’ effects on activation of these five signaling cascades by both physiological and pathophysiological concentrations of CCK, as well as by 12- O-tetradecanoylphobol-13-acetate (TPA), a PKC-activator, were examined. CCK/TPA activation of focal adhesion kinases(PYK2/p125FAK) and the accompanying adapter proteins (paxillin/p130CAS), Mek1/2, and p44/42, but not c-Raf or other MAPKs (JNK/p38), were mediated by PAK4. Activation of PI3K/Akt/p70s6K was independent of PAK4, whereas GSK3 and β-catenin stimulation was PAK4-dependent. These results, coupled with recent studies showing PAK4 is important in pancreatic fluid/electrolyte/enzyme secretion and acinar cell growth, show that PAK4 plays an important role in different cellular signaling cascades, which have been shown to mediate numerous physiological and pathophysiological processes in pancreatic acinar cells. NEW & NOTEWORTHY In pancreatic acinar cells, cholecystokinin (CCK) or 12- O-tetradecanoylphobol-13-acetate (TPA) activation of focal adhesion kinases (p125FAK,PYK2) and its accompanying adapter proteins, p130CAS/paxillin; Mek1/2, p44/42, GSK3, and β-catenin are mediated by PAK4. PI3K/Akt/p70s6K, c-Raf, JNK, or p38 pathways are independent of PAK4 activation.
50
Reddy, Pavankumar N. G., Jenna Wood, Chad E. Harris, Ke Xu, Meaghan McGuinness, Maria Radu, Rachelle Kosoff, Jonathan Chernoff e David A. Williams. "Kinase Activity Of Pak2, An Effector Of Rac/CDC42 and Its Interaction With β-PIX Is Required For Murine Hematopoietic Stem Cell Shape, F-Actin Formation, Directional Migration In Vitro and For HSPC Homing To Bone Marrow In Vivo". Blood 122, n. 21 (15 novembre 2013): 2419. http://dx.doi.org/10.1182/blood.v122.21.2419.2419.
Testo completoAbstract (sommario):
Abstract Hematopoietic stem and progenitor cell (HSPC) migration, marrow homing and engraftment are key physiological processes regulating hematopoiesis post transplantation. These processes are the result of the orchestrated actions of multiple extracellular stimuli, which regulate actin remodeling, cell polarity, chemotaxis and cell-cell interactions. In HSPC, the Rho GTPases Rac and CDC42 act as molecular switches that integrate extracellular stimuli in a spatially regulated manner to control cell migration and mediate homing to marrow and mobilization as well as cell survival/ proliferation pathways to mediate engraftment(Gu et al., Science 2003; Cancelas et al., Nature Medicine 2005; Wang et al., Blood 2006). Using an inhibitory peptide against Group A p21 activated kinases (Pak1-3), key effectors of Rac/ CDC42 and individual Pak1 & 2 genetic knock-out mice, we recently demonstrated that Pak kinases, specifically Pak2, are important for HSPC homing and engraftment (Dorrance et al., Blood 2013). Pak2 is a multi-domain protein that contains a C-terminal kinase domain and multiple N-terminal protein-interaction domains. Among these is a non-classical SH3-binding site for the guanine-nucleotide-exchange factor β-PIX, which was shown to be critical for both activation of Rac1 and its localization to and induction of membrane ruffles (Klooster et al., Journal of Cell Biology 2006). In this study we further explored the role of these domains of Pak2 in key HSPC functions, including homing to bone marrow in vivo. We employed a multi-cistronic retrovirus vector that simultaneously deleted floxed endogenous Pak2 gene sequences and rescued with either wild type (WT), a kinase dead (KD) mutant (K278A, defective in auto/ trans phosphorylation) or a Δβ-PIX mutant, (P185/R186A, that cannot bind to β-PIX). As previously demonstrated deletion of Pak2 (Pak2 Δ/Δ) was associated with abnormal SDF-1 stimulated cell protrusions containing F-actin (as demonstrated by confocal and electron microscopy) and these HSPC displayed decreased directional migration (Euclidean distance in Pak2Δ/Δ vs. Pak2WT/WT: 39.6µm ±9.6 vs. 96.6µm ±21.6; P<0.05). This phenotype of abnormal cell protrusions and decreased directional migration was rescued by expressing Pak2-WT (Pak2WT/WT vs. Pak2-WT: 96.6µm ±21.6 vs. 74.0µm ±18.7; P: not significant) but not by expressing Pak2-KD (Pak2WT/WT vs. Pak2-KD: 96.6µm ±21.6 vs. 33.6µm ±6.3; P<0.05) demonstrating the requirement of Pak2 kinase activity in SDF1-induced cell polarization and directed cell migration. Interestingly, we found abnormal F-actin clustering associated with defective polarization (by confocal microscopy) and decreased velocity of cell migration in time-lapsed video microscopy when Pak2-deletion was rescued with Pak2-Δβ-PIX (velocity of migration Pak2WT/WT vs. Pak2-Δβ-PIX, 0.32µm/minute ±0.02 vs. 0.13µm/minute ±0.02; P<0.001), indicating the requirement of β-PIX exchange factor interaction with Pak2 in directed migration. To test whether these in vitro phenotypes were associated with changes in homing efficiency to bone marrow, we performed in vivo homing assays of rescued HSPC. Transduced, GFP-sorted Lin-Sca1+Kit+ cells of each genotype were injected into lethally-irradiated C57BL/6 recipient mice (N= 12-29 /genotype). Twelve hours post-transplantation the number of EGFP+ cells in the bone marrow was determined and percent homing is calculated. Compared to Pak2 WT/WT, Pak2Δ/Δ HSPC displayed reduced homing (99.26%± 4.9 vs. 53.4% ± 4.2; P< 0.0001). The homing defect was rescued by Pak2-WT (Pak2WT/WT vs. Pak2-WT rescue: 99.26%± 4.9 vs. 86% ± 8.5; P: not significant). However neither Pak2-KD nor Pak2-Δβ-PIX rescued in vivo homing: 99.26% ±4.9 vs. 38.9% ±3.7 vs. 33.0%± 6.0; P< 0.0001 each mutant vs.Pak2WT/WT) proving the necessity of kinase activity and interaction with β-PIX for bone marrow homing. Taken together we show that both Pak2-kinase activity and its interaction with β-PIX exchange factor are required for coordinated HSPC F-actin formation and cell polarization, directed cell migration in vitro and homing to bone marrow in vivo. These data directly link the in vitro effects of Pak2 kinase with in vivo bonemarrow homing. Note All p values are calculated by Mann Whitney test. Disclosures: No relevant conflicts of interest to declare.