Journal articles: 'Is91'

1

Xu, De-Qi, John O. Cisar, Nicholas Ambulos, Donald H. Burr, and Dennis J. Kopecko. "Molecular Cloning and Characterization of Genes for Shigella sonnei Form I O Polysaccharide: Proposed Biosynthetic Pathway and Stable Expression in a Live Salmonella Vaccine Vector." Infection and Immunity 70, no. 8 (August 2002): 4414–23. http://dx.doi.org/10.1128/iai.70.8.4414-4423.2002.

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ABSTRACT The gene region for biosynthesis of Shigella sonnei form I O polysaccharide (O-Ps) and flanking sequences, totaling >18 kb, was characterized by deletion analysis to define a minimal construct for development of Salmonella-based live vaccine vector strains. Lipopolysaccharide (LPS) expression and DNA sequence studies of plasmid deletion derivatives indicated form I O-Ps expression from a 12.3-kb region containing a putative promoter and 10 contiguous open reading frames (ORFs), one of which is the transposase of IS630. A detailed biosynthetic pathway, consistent with the predicted functions of eight of the nine essential ORFs and the form I O-Ps structure, is proposed. Further sequencing identified partial IS elements (i.e., IS91 and IS630) and wzz upstream of the form I coding region and a fragment of aqpZ and additional full or partial IS elements (i.e., IS629, IS91, and IS911) downstream of this region. The stability of plasmid-based form I O-Ps expression was greater from low-copy vectors than from high-copy vectors and was enhanced by deletion of the downstream IS91 from plasmid inserts. Both core-linked (i.e., LPS) and non-core-linked (i.e., capsule-like) surface expression of form I O-Ps were detected by Western blotting and silver staining of polyacrylamide gel electrophoresis-separated Shigella and Escherichia coli extracts. However, salmonellae, which have a core that is chemically dissimilar to that of shigellae, expressed only non-core-linked surface-associated form I O-Ps. Finally, attenuated Salmonella enterica serovar Typhi live vaccine vector candidates, containing minimal-sized form I operon constructs, elicited immune protection in mice against virulent S. sonnei challenge, thereby supporting the promise of live, oral vaccines for the prevention of shigellosis.

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Turner, Sally A., Shelley N. Luck, Harry Sakellaris, Kumar Rajakumar, and Ben Adler. "Nested Deletions of the SRL Pathogenicity Island ofShigella flexneri 2a." Journal of Bacteriology 183, no. 19 (October 1, 2001): 5535–43. http://dx.doi.org/10.1128/jb.183.19.5535-5543.2001.

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ABSTRACT In this study, we determined the boundaries of a 99-kb deletable element of Shigella flexneri 2a strain YSH6000. The element, designated the multiple-antibiotic resistance deletable element (MRDE), had recently been found to contain a 66-kb pathogenicity island (PAI)-like element (designated the SRL PAI) which carries the Shigella resistance locus (SRL), encoding resistance determinants to streptomycin, ampicillin, chloramphenicol, and tetracycline. The YSH6000 MRDE was found to be flanked by two identical IS91 elements present at the S. flexneri homologs of the Escherichia coli genesputA and mdoA on NotI fragment D. Sequence data from two YSH6000-derived MRDE deletants, YSH6000T and S2430, revealed that deletion of the MRDE occurred between the two flanking IS91 elements, resulting in a single IS91 element spanning the two original IS91 loci. Selection for the loss of tetracycline resistance confirmed that the MRDE deletion occurred reproducibly from the same chromosomal site and also showed that the SRL PAI and the SRL itself were capable of independent deletion from the chromosome, thus revealing a unique set of nested deletions. The excision frequency of the SRL PAI was estimated to be 10−5 per cell in the wild type, and mutation of a P4-like integrase gene (int) at the left end of the SRL PAI revealed that int mediates precise deletion of the PAI.

3

Schlör, Stefan, Sabine Riedl, Julia Blaß, and Joachim Reidl. "Genetic Rearrangements of the Regions Adjacent to Genes Encoding Heat-Labile Enterotoxins (eltAB) of EnterotoxigenicEscherichia coli Strains." Applied and Environmental Microbiology 66, no. 1 (January 1, 2000): 352–58. http://dx.doi.org/10.1128/aem.66.1.352-358.2000.

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ABSTRACT One of the most common bacterially mediated diarrheal infections is caused by enterotoxigenic Escherichia coli (ETEC) strains. ETEC-derived plasmids are responsible for the distribution of the genes encoding the main toxins, namely, the heat-labile and heat-stable enterotoxins. The origins and transfer modes (intra- or interplasmid) of the toxin-encoding genes have not been characterized in detail. In this study, we investigated the DNA regions located near the heat-labile enterotoxin-encoding genes (eltAB) of several clinical isolates. It was found that the eltAB region is flanked by conserved 236- and 280-bp regions, followed by highly variable DNA sequences which consist mainly of partial insertion sequence (IS) elements. Furthermore, we demonstrated that rearrangements of the eltAB region of one particular isolate, which harbors an IS91R sequence next toeltAB, could be produced by a recA-independent but IS91 sequence-dependent mechanism. Possible mechanisms of dissemination of IS element-associated enterotoxin-encoding genes are discussed.

4

del Pilar Garcillan-Barcia, M., Irantzu Bernales, M. Victoria Mendiola, and Fernando de la Cruz. "Single-stranded DNA intermediates in IS91 rolling-circle transposition." Molecular Microbiology 39, no. 2 (January 2001): 494–502. http://dx.doi.org/10.1046/j.1365-2958.2001.02261.x.

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Mendiola, M. V., I. Bernales, and F. de la Cruz. "Differential roles of the transposon termini in IS91 transposition." Proceedings of the National Academy of Sciences 91, no. 5 (March 1, 1994): 1922–26. http://dx.doi.org/10.1073/pnas.91.5.1922.

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Diaz-Aroca, E., M. V. Mendiola, J. C. Zabala, and F. de la Cruz. "Transposition of IS91 does not generate a target duplication." Journal of Bacteriology 169, no. 1 (1987): 442–43. http://dx.doi.org/10.1128/jb.169.1.442-443.1987.

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7

Schleinitz, Kathleen M., Tatiana Vallaeys, and Sabine Kleinsteuber. "Structural Characterization of ISCR8, ISCR22, and ISCR23, Subgroups of IS91-Like Insertion Elements." Antimicrobial Agents and Chemotherapy 54, no. 10 (July 12, 2010): 4321–28. http://dx.doi.org/10.1128/aac.00006-10.

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ABSTRACT Analysis of ISCR8 (ISPps1) revealed that this group of insertion elements has to be subdivided into three subgroups: ISCR8, ISCR22, and ISCR23. The distinction of three subgroups is supported by phylogenetic analysis of the transposase open reading frames (ORFs). Comparison of over 20 complete and partial ISCR8/22/23 elements identified oriIS candidate sequences for all groups and a terIS candidate sequence for ISCR8. The oriIS sequences, their distance to the transposase ORFs, and the sequence of this intervening region are group specific, further supporting the definition of two new ISCR elements. ISCR8/22/23 have a very broad host range, including Gram-positive and Gram-negative bacteria, among which are several (opportunistic) pathogens. The IS often resides on plasmids or in the vicinity of other mobile elements and is mostly associated with genes for the degradation of halo- or nitro-aromatics. However, in one case ISCR8 was found in the neighborhood of an antibiotic resistance determinant in Klebsiella pneumoniae. ISCR8 resembles other IS91 family elements in mediating genetic rearrangements by homologous recombination between two copies. In Delftia acidovorans this led to the loss of the genes encoding dichlorprop cleavage. In conclusion, this study shows that ISCR8 could be a fully functional and active member of the IS91 family of insertion elements.

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Mendiola, M. V., Y. Jubete, and F. de la Cruz. "DNA sequence of IS91 and identification of the transposase gene." Journal of Bacteriology 174, no. 4 (1992): 1345–51. http://dx.doi.org/10.1128/jb.174.4.1345-1351.1992.

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GarcillÃ¡n-Barcia, M. Pilar, and Fernando Cruz. "Distribution of IS91 family insertion sequences in bacterial genomes: evolutionary implications." FEMS Microbiology Ecology 42, no. 2 (November 2002): 303–13. http://dx.doi.org/10.1111/j.1574-6941.2002.tb01020.x.

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GARCILLANBARCIA, M. "Distribution of IS91 family insertion sequences in bacterial genomes: evolutionary implications." FEMS Microbiology Ecology 42, no. 2 (November 2002): 303–13. http://dx.doi.org/10.1016/s0168-6496(02)00340-9.

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Toleman, Mark A., Peter M. Bennett, and Timothy R. Walsh. "ISCR Elements: Novel Gene-Capturing Systems of the 21st Century?" Microbiology and Molecular Biology Reviews 70, no. 2 (June 2006): 296–316. http://dx.doi.org/10.1128/mmbr.00048-05.

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SUMMARY “Common regions” (CRs), such as Orf513, are being increasingly linked to mega-antibiotic-resistant regions. While their overall nucleotide sequences show little identity to other mobile elements, amino acid alignments indicate that they possess the key motifs of IS91-like elements, which have been linked to the mobility ent plasmids in pathogenic Escherichia coli. Further inspection reveals that they possess an IS91-like origin of replication and termination sites (terIS), and therefore CRs probably transpose via a rolling-circle replication mechanism. Accordingly, in this review we have renamed CRs as ISCRs to give a more accurate reflection of their functional properties. The genetic context surrounding ISCRs indicates that they can procure 5′ sequences via misreading of the cognate terIS, i.e., “unchecked transposition.” Clinically, the most worrying aspect of ISCRs is that they are increasingly being linked with more potent examples of resistance, i.e., metallo-β-lactamases in Pseudomonas aeruginosa and co-trimoxazole resistance in Stenotrophomonas maltophilia. Furthermore, if ISCR elements do move via “unchecked RC transposition,” as has been speculated for ISCR1, then this mechanism provides antibiotic resistance genes with a highly mobile genetic vehicle that could greatly exceed the effects of previously reported mobile genetic mechanisms. It has been hypothesized that bacteria will surprise us by extending their “genetic construction kit” to procure and evince additional DNA and, therefore, antibiotic resistance genes. It appears that ISCR elements have now firmly established themselves within that regimen.

12

Bernales, Irantzu, M. Victoria Mendiola, and Fernando de la Cruz. "Intramolecular transposition of insertion sequence IS91 results in second-site simple insertions." Molecular Microbiology 33, no. 2 (July 1999): 223–34. http://dx.doi.org/10.1046/j.1365-2958.1999.01432.x.

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13

Schleinitz, Kathleen M., Sabine Kleinsteuber, Tatiana Vallaeys, and Wolfgang Babel. "Localization and Characterization of Two Novel Genes Encoding Stereospecific Dioxygenases Catalyzing 2(2,4-Dichlorophenoxy)propionate Cleavage in Delftia acidovorans MC1." Applied and Environmental Microbiology 70, no. 9 (September 2004): 5357–65. http://dx.doi.org/10.1128/aem.70.9.5357-5365.2004.

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ABSTRACT Two novel genes, rdpA and sdpA, encoding the enantiospecific α-ketoglutarate dependent dioxygenases catalyzing R,S-dichlorprop cleavage in Delftia acidovorans MC1 were identified. Significant similarities to other known genes were not detected, but their deduced amino acid sequences were similar to those of other α-ketoglutarate dioxygenases. RdpA showed 35% identity with TauD of Pseudomonas aeruginosa, and SdpA showed 37% identity with TfdA of Ralstonia eutropha JMP134. The functionally important amino acid sequence motif HX(D/E)X23-26(T/S)X114-183HX10-13R/K, which is highly conserved in group II α-ketoglutarate-dependent dioxygenases, was present in both dichlorprop-cleaving enzymes. Transposon mutagenesis of rdpA inactivated R-dichlorprop cleavage, indicating that it was a single-copy gene. Both rdpA and sdpA were located on the plasmid pMC1 that also carries the lower pathway genes. Sequencing of a 25.8-kb fragment showed that the dioxygenase genes were separated by a 13.6-kb region mainly comprising a Tn501-like transposon. Furthermore, two copies of a sequence similar to IS91-like elements were identified. Hybridization studies comparing the wild-type plasmid and that of the mutant unable to cleave dichlorprop showed that rdpA and sdpA were deleted, whereas the lower pathway genes were unaffected, and that deletion may be caused by genetic rearrangements of the IS91-like elements. Two other dichlorprop-degrading bacterial strains, Rhodoferax sp. strain P230 and Sphingobium herbicidovorans MH, were shown to carry rdpA genes of high similarity to rdpA from strain MC1, but sdpA was not detected. This suggested that rdpA gene products are involved in the degradation of R-dichlorprop in these strains.

14

Mendiola, M. V., and F. Cruz. "Specificity of insertion of IS91, an insertion sequence present in ?-haemolysin plasmids of Escherichia coli." Molecular Microbiology 3, no. 7 (July 1989): 979–84. http://dx.doi.org/10.1111/j.1365-2958.1989.tb00247.x.

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15

Toleman, M. A. "Common regions e.g. orf513 and antibiotic resistance: IS91-like elements evolving complex class 1 integrons." Journal of Antimicrobial Chemotherapy 58, no. 1 (May 2, 2006): 1–6. http://dx.doi.org/10.1093/jac/dkl204.

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Pedró, Laura, Rosa C. Baños, Sonia Aznar, Cristina Madrid, Carlos Balsalobre, and Antonio Juárez. "Antibiotics Shaping Bacterial Genome: Deletion of an IS91 Flanked Virulence Determinant upon Exposure to Subinhibitory Antibiotic Concentrations." PLoS ONE 6, no. 11 (November 11, 2011): e27606. http://dx.doi.org/10.1371/journal.pone.0027606.

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Mendiola, M. Victoria, and Fernando de la Cruz. "IS91 transposase is related to the rolling-circle-type replication proteins of the pUB110 family of plasmids." Nucleic Acids Research 20, no. 13 (1992): 3521. http://dx.doi.org/10.1093/nar/20.13.3521.

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Chen, Wenbo, Yu Zhang, and Jiandui Mi. "Assessing Antibiotic-Resistant Genes in University Dormitory Washing Machines." Microorganisms 12, no. 6 (May 30, 2024): 1112. http://dx.doi.org/10.3390/microorganisms12061112.

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University dormitories represent densely populated environments, and washing machines are potential sites for the spread of bacteria and microbes. However, the extent of antibiotic resistance gene (ARG) variation in washing machines within university dormitories and their potential health risks are largely unknown. To disclose the occurrence of ARGs and antibiotic-resistant bacteria from university dormitories, we collected samples from washing machines in 10 dormitories and used metagenomic sequencing technology to determine microbial and ARG abundance. Our results showed abundant microbial diversity, with Proteobacteria being the dominant microorganism that harbors many ARGs. The majority of the existing ARGs were associated with antibiotic target alteration and efflux, conferring multidrug resistance. We identified tnpA and IS91 as the most abundant mobile genetic elements (MGEs) in washing machines and found that Micavibrio aeruginosavorus, Aquincola tertiaricarbonis, and Mycolicibacterium iranicum had high levels of ARGs. Our study highlights the potential transmission of pathogens from washing machines to humans and the surrounding environment. Pollution in washing machines poses a severe threat to public health and demands attention. Therefore, it is crucial to explore effective methods for reducing the reproduction of multidrug resistance.

19

Wang, Yuchen, Beibei Chen, Mengzhuo Cao, Linshan Sima, David Prangishvili, Xiangdong Chen, and Mart Krupovic. "Rolling-circle replication initiation protein of haloarchaeal sphaerolipovirus SNJ1 is homologous to bacterial transposases of the IS91 family insertion sequences." Journal of General Virology 99, no. 3 (March 1, 2018): 416–21. http://dx.doi.org/10.1099/jgv.0.001009.

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Schuster, Judith, Jessica Purswani, Uta Breuer, Clementina Pozo, Hauke Harms, Roland H. Müller, and Thore Rohwerder. "Constitutive Expression of the Cytochrome P450 EthABCD Monooxygenase System Enables Degradation of Synthetic Dialkyl Ethers in Aquincola tertiaricarbonis L108." Applied and Environmental Microbiology 79, no. 7 (January 25, 2013): 2321–27. http://dx.doi.org/10.1128/aem.03348-12.

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ABSTRACTInRhodococcus ruberIFP 2001,Rhodococcus zopfiiIFP 2005, andGordoniasp. strain IFP 2009, the cytochrome P450 monooxygenase EthABCD catalyzes hydroxylation of methoxy and ethoxy residues in the fuel oxygenates methyltert-butyl ether (MTBE), ethyltert-butyl ether (ETBE), andtert-amyl methyl ether (TAME). The expression of the IS3-type transposase-flankedethgenes is ETBE dependent and controlled by the regulator EthR (C. Malandain et al., FEMS Microbiol. Ecol. 72:289–296, 2010). In contrast, we demonstrated by reverse transcription-quantitative PCR (RT-qPCR) that the betaproteobacteriumAquincola tertiaricarbonisL108, which possesses theethABCDgenes but lacksethR, constitutively expresses the P450 system at high levels even when growing on nonether substrates, such as glucose. The mutant strainA. tertiaricarbonisL10, which is unable to degrade dialkyl ethers, resulted from a transposition event mediated by a rolling-circle IS91-type element flanking theethgene cluster in the wild-type strain L108. The constitutive expression of Eth monooxygenase is likely initiated by the housekeeping sigma factor σ70, as indicated by the presence in strain L108 of characteristic −10 and −35 binding sites upstream ofethAwhich are lacking in strain IFP 2001. This enables efficient degradation of diethyl ether, diisopropyl ether, MTBE, ETBE, TAME, andtert-amyl ethyl ether (TAEE) without any lag phase in strain L108. However, ethers with larger residues,n-hexyl methyl ether, tetrahydrofuran, and alkyl aryl ethers, were not attacked by the Eth system at significant rates in resting-cell experiments, indicating that the residue in the ether molecule which is not hydroxylated also contributes to the determination of substrate specificity.

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Lewis, Gentry L., Robert J. Fenton, Etsuko N. Moriyama, John Dustin Loy, and Rodney A. Moxley. "Association of ISVsa3 with Multidrug Resistance in Salmonella enterica Isolates from Cattle (Bos taurus)." Microorganisms 11, no. 3 (March 1, 2023): 631. http://dx.doi.org/10.3390/microorganisms11030631.

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Salmonella enterica is, globally, an important cause of human illness with beef being a significant attributable source. In the human patient, systemic Salmonella infection requires antibiotic therapy, and when strains are multidrug resistant (MDR), no effective treatment may be available. MDR in bacteria is often associated with the presence of mobile genetic elements (MGE) that mediate horizontal spread of antimicrobial resistance (AMR) genes. In this study, we sought to determine the potential relationship of MDR in bovine Salmonella isolates with MGE. The present study involved 111 bovine Salmonella isolates obtained collectively from specimens derived from healthy cattle or their environments at Midwestern U.S. feedyards (2000–2001, n = 19), or specimens from sick cattle submitted to the Nebraska Veterinary Diagnostic Center (2010–2020, n = 92). Phenotypically, 33/111 isolates (29.7%) were MDR (resistant to ≥3 drug classes). Based on whole-genome sequencing (WGS; n = 41) and PCR (n = 111), a MDR phenotype was strongly associated (OR = 186; p < 0.0001) with carriage of ISVsa3, an IS91-like Family transposase. In all 41 isolates analyzed by WGS ((31 MDR and 10 non-MDR (resistant to 0–2 antibiotic classes)), MDR genes were associated with carriage of ISVsa3, most often on an IncC type plasmid carrying blaCMY-2. The typical arrangement was floR, tet(A), aph(6)-Id, aph(3″)-Ib, and sul2 flanked by ISVsa3. These results suggest that AMR genes in MDR S. enterica isolates of cattle are frequently associated with ISVsa3 and carried on IncC plasmids. Further research is needed to better understand the role of ISVsa3 in dissemination of MDR Salmonella strains.

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Mei, Li, Yang Song, Xiao Liu, Kun Li, Xu Guo, Li Liu, Yang Liu, et al. "Characterization and Implications of IncP-2A Plasmid pMAS152 Harboring Multidrug Resistance Genes in Extensively Drug-Resistant Pseudomonas aeruginosa." Microorganisms 12, no. 3 (March 12, 2024): 562. http://dx.doi.org/10.3390/microorganisms12030562.

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Bacterial antimicrobial resistance (AMR) poses a significant global public health challenge. The escalation of AMR is primarily attributed to the horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs), often facilitated by plasmids. This underscores the critical need for a comprehensive understanding of the resistance mechanisms and transmission dynamics of these plasmids. In this study, we utilized in vitro drug sensitivity testing, conjugation transfer assays, and whole-genome sequencing to investigate the resistance mechanism of an extensively drug-resistant (XDR) Pseudomonas aeruginosa clinical isolate, MAS152. We specifically focused on analyzing the drug-resistant plasmid pMAS152 it harbors and its potential for widespread dissemination. Bioinformatics analysis revealed that MAS152 carries a distinct IncpP-2A plasmid, pMAS152, characterized by a 44.8 kb multidrug resistance (MDR) region. This region houses a 16S rRNA methyltransferase (16S-RMTase) gene, rmtB, conferring high-level resistance to aminoglycoside antibiotics. Notably, this region also contains an extended-spectrum β-Lactamase (ESBL) gene, blaPER-1, and an efflux pump operon, tmexCD-oprJ, which mediate resistance to β-Lactams and quinolone antibiotics, respectively. Such a combination of ARGs, unprecedented in reported plasmids, could significantly undermine the effectiveness of first-line antibiotics in treating P. aeruginosa infections. Investigation into the genetic environment of the MDR region suggests that Tn2 and IS91 elements may be instrumental in the horizontal transfer of rmtB. Additionally, a complex Class I integron with an ISCR1 structure, along with TnAs1, seems to facilitate the horizontal transfer of blaPER-1. The conjugation transfer assay, coupled with the annotation of conjugation-related genes and phylogenetic analysis, indicates that the plasmid pMAS152 functions as a conjugative plasmid, with other genus Pseudomonas species as potential hosts. Our findings provide vital insights into the resistance mechanisms and transmission potential of the XDR P. aeruginosa isolate MAS152, underlining the urgent need for novel strategies to combat the spread of AMR. This study highlights the complex interplay of genetic elements contributing to antibiotic resistance and underscores the importance of continuous surveillance of emerging ARGs in clinical isolates.

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Polzin, Kayla M., Dennis Romero, Mariko Shimizu-Kadota, Todd R. Klaenhammer, and Larry L. McKay. "Copy Number and Location of Insertion Sequences ISS1 and IS981 in Lactococci and Several Other Lactic Acid Bacteria." Journal of Dairy Science 76, no. 5 (May 1993): 1243–52. http://dx.doi.org/10.3168/jds.s0022-0302(93)77453-6.

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Ando, K., S. Shioda, H. Handa, and K. Kataoka. "Isolation and characterization of an alternatively spliced variant of transcription factor Islet-1." Journal of Molecular Endocrinology 31, no. 3 (December 1, 2003): 419–25. http://dx.doi.org/10.1677/jme.0.0310419.

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The LIM homeodomain protein Islet-1 (Isl1), one of the earliest markers for motor neuron differentiation, is also expressed in all classes of islet cells in the pancreas. Isl1 is known to bind and regulate the promoters of the insulin, glucagon and somatostatin genes. In this study, we describe isolation of a novel isl1 cDNA species from the mouse islet beta cell line betaTC6, which arose from the utilization of an alternative splicing acceptor site in the fifth exon. This shorter cDNA encodes an Isl1 isoform (Isl1-beta) lacking the carboxy-terminal 23 amino acids of the previously reported product Isl1-alpha. Although the level of isl1-beta mRNA is much lower than that of isl1-alpha, isl1-beta is preferentially expressed in murine insulinoma cell lines but not in glucagonoma cell line. Upon transient transfection, both Isl1-alpha and Isl1-beta accumulate in the nuclei of murine insulinoma cells. We found that Isl1-beta is a relatively more potent transcriptional activator of the insulin promoter than Isl1-alpha and that the Isl1-alpha isoform undergoes phosphorylation. Therefore, the transcriptional activity of Isl1 is potentially regulated by the alternative splicing of its mRNA and by phosphorylation.

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Reimmann, Cornelia, and Dieter Haas. "Mode of Replicon Fusion Mediated by the Duplicated Insertion Sequence IS21 in Escherichia coli." Genetics 115, no. 4 (April 1, 1987): 619–25. http://dx.doi.org/10.1093/genetics/115.4.619.

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ABSTRACT The insertion sequence IS21 (2.1 kb) originating from the broad-host-range IncP plasmid R68 transposes infrequently; by contrast, the IS21 tandem repeat found on the derivative R68.45 is highly active in transpositional mobilization of other replicons in a variety of Gram-negative bacteria. The mobilized plasmids are joined to R68.45 by single IS21 copies in direct orientation.—The formation of IS21 tandem duplications was observed in cointegrates between R68.45 and pBR325::IS21 and also in an RP1::IS21 plasmid derivative in which a segment located between two directly repeated copies of IS21 was deleted spontaneously. We speculate that IS21 tandem repeats can arise when the termini of two IS21 elements are specifically joined in a transposition or deletion event.—A resistance gene flanked by two IS21 elements in direct orientation did not behave as a transposon. The Ω fragment carrying transcription and translation stop signals was inserted into various sites of the IS21 tandem repeat; in this way it could be shown that the left IS21 element (which is next to the kanamycin resistance gene in R68.45) was 100 times more active in cointegrate formation than was the righthand element.—Cointegrates between the conjugative plasmid R751 and pBR325 derivatives carrying IS21 and IS21::Ω in tandem contained a single IS21 at one replicon junction and a single IS21::Ω at the other. In the IS21 duplications the inner IS21 ends were preferentially recognized (presumably by IS21 transposase), whereas the outer termini were not required for cointegrate formation. Based on these findings a conservative (simple) pathway of transposition is proposed for R68.45 and other plasmids with an IS21 tandem repeat. In this model R68.45 is pictured as a large transposon whose ends are joined together to form a circular molecule which is capable of autonomous replication.

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Rivera-Torruco, Guadalupe, Carolina A. Martínez-Mendiola, Tania Angeles-Floriano, Gustavo Alberto Jaimes-Ortega, José Luis Maravillas-Montero, Rodolfo García-Contreras, Yolanda González, et al. "Isthmin 1 is Expressed by Progenitor-Like Cells in the Lung: Phenotypical Analysis of Isthmin 1+ Hematopoietic Stem-Like Cells in Homeostasis and during Infection." Journal of Immunology Research 2022 (April 1, 2022): 1–13. http://dx.doi.org/10.1155/2022/2909487.

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The process by which blood cells are generated has been widely studied in homeostasis and during pathogen-triggered inflammatory response. Recently, murine lungs have been shown to be a significant source of hematopoietic progenitors in a process known as extramedullary hematopoiesis. Using multiparametric flow cytometry, we have identified mesenchymal, endothelial, and hematopoietic progenitor cells that express the secreted small protein Isthmin 1 (ISM1). Further characterization of hematopoietic progenitor cells indicated that ISM1+ Lineage- Sca-1+ c-kit+ (ISM1+ LSK) cells are enriched in short-term hematopoietic stem cells (ST-HSCs). Moreover, most Sca-1+ ISM1+ cells express the residence marker CD49a, and this correlated with their localization in the extravascular region of the lung, indicating that ISM1+ cells are lung-resident cells. We also observed that ISM1+ cells express TLR4, TLR5, and TLR9, and, in a mouse model of sepsis induced by P. aeruginosa, we observed that all the LSK and ISM1+LSK cells were affected. We conclude that ISM1 is a novel biomarker associated with progenitor-like cells. ISM1+ cells are involved in the response to a bacterial challenge, suggesting an association between ISM1-producing cells and dangerous inflammatory responses like sepsis.

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Rivera-Torruco, Guadalupe, Carolina Abigail Mendiola, Tania Angeles Floriano, Rafael Franco, Israel Parra-Ortega, Armando Vilchis, José Luis Maravillas-Montero, et al. "Isthmin 1 identifies a subset of lung hematopoietic stem cells and it is associated with systemic inflammation." Journal of Immunology 202, no. 1_Supplement (May 1, 2019): 118.18. http://dx.doi.org/10.4049/jimmunol.202.supp.118.18.

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Abstract Hematopoiesis is a highly regulated process and it’s widely described in bone marrow, the classical niche for hematopoietic stem cells (HSCs). The lungs are a novel niche of HSCs, as recently described by Lefrançais in 2017, however, little is known about the nature of these cells. Isthmin 1 (ISM1) is a secreted molecule important in developmental hematopoiesis in zebrafish; moreover, it is known that murine lungs express high levels of ISM1 and its secretion is altered after LPS challenge. In this work we performed multiparametric flow cytometry identifying a subpopulation of lung-resident HSCs expressing ISM1. Then we wanted to assess if HSCs ISM1+ cells are affected under inflammatory insults. Acute infection in mice with Pseudomonas aeruginosa showed that lung-derived HSCs ISM1+ are increased, indicating that the lung-HSCs are perturbed. Due to our model produced systemic inflammation we sought to investigate whether circulating ISM1+ cells were affected, we found that the percentage and absolute numbers of ISM1+ cells in blood were slightly diminished. Since ISM1 is a secreted molecule we evaluated its plasmatic levels by ELISA. We discovered a reduction in ISM1 plasmatic levels during murine sepsis with Pseudomonas aeruginosa. Then, we sought to analyze ISM1 levels in human inflammation; we retrieved samples from pediatric individuals with sepsis and adult patients with 2th and 3th grade burn injuries, and in both cases, we detected reduced levels of plasmatic ISM1. Our data suggest that ISM1 is likely a regulator of hematopoiesis in the lung but also may have a function in the regulation of systemic inflammation in mice and humans. We suggest that ISM1 is a novel biomarker of systemic inflammation.

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Shao, Weijuan, Vivian Szeto, Zhuolun Song, Lili Tian, Zhong-Ping Feng, M. Cristina Nostro, and Tianru Jin. "The LIM homeodomain protein ISL1 mediates the function of TCF7L2 in pancreatic beta cells." Journal of Molecular Endocrinology 61, no. 1 (July 2018): 1–12. http://dx.doi.org/10.1530/jme-17-0181.

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Pancreatic β-cell Tcf7l2 deletion or its functional knockdown suggested the essential role of this Wnt pathway effector in controlling insulin secretion, glucose homeostasis and β-cell gene expression. As the LIM homeodomain protein ISL1 is a suggested Wnt pathway downstream target, we hypothesize that it mediates metabolic functions of TCF7L2. We aimed to determine the role of ISL1 in mediating the function of TCF7L2 and the incretin hormone GLP-1 in pancreatic β-cells. The effect of dominant negative TCF7L2 (TCF7L2DN) mediated Wnt pathway functional knockdown on Isl1 expression was determined in βTCFDN mouse islets and in the rat insulinoma cell line INS-1 832/13. Luciferase reporter assay and chromatin immunoprecipitation were utilized to determine whether Isl1 is a direct downstream target of Tcf7l2. TCF7L2DN adenovirus infection and siRNA-mediated Isl1 knockdown on β-cell gene expression were compared. Furthermore, Isl1 knockdown on GLP-1 stimulated β-catenin S675 phosphorylation and insulin secretion was determined. We found that TCF7L2DN repressed ISL1 levels in βTCFDN islets and the INS-1 832/13 cell line. Wnt stimulators enhanced Isl1 promoter activity and binding of TCF7L2 on Isl1 promoter. TCF7L2DN adenovirus infection and Isl1 knockdown generated similar repression on expression of β-cell genes, including the ones that encode GLUT2 and GLP-1 receptor. Either TCF7L2DN adenovirus infection or Isl1 knockdown attenuated GLP-1-stimulated β-catenin S675 phosphorylation in INS-1 832/13 cells or mouse islets and GLP-1 stimulated insulin secretion in INS-1 832/13 or MIN6 cells. Our observations support the existence of TCF7L2–ISL1 transcriptional network, and we suggest that this network also mediates β-cell function of GLP-1.

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Castinetti, F., M. L. Brinkmeier, A. H. Mortensen, K. R. Vella, P. Gergics, T. Brue, A. N. Hollenberg, L. Gan, and S. A. Camper. "ISL1 Is Necessary for Maximal Thyrotrope Response to Hypothyroidism." Molecular Endocrinology 29, no. 10 (October 1, 2015): 1510–21. http://dx.doi.org/10.1210/me.2015-1192.

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Abstract ISLET1 is a homeodomain transcription factor necessary for development of the pituitary, retina, motor neurons, heart, and pancreas. Isl1-deficient mice (Isl1−/−) die early during embryogenesis at embryonic day 10.5 due to heart defects, and at that time, they have an undersized pituitary primordium. ISL1 is expressed in differentiating pituitary cells in early embryogenesis. Here, we report the cell-specific expression of ISL1 and assessment of its role in gonadotropes and thyrotropes. Isl1 expression is elevated in pituitaries of Cga−/− mice, a model of hypothyroidism with thyrotrope hypertrophy and hyperplasia. Thyrotrope-specific disruption of Isl1 with Tshb-cre is permissive for normal serum TSH, but T4 levels are decreased, suggesting decreased thyrotrope function. Inducing hypothyroidism in normal mice causes a reduction in T4 levels and dramatically elevated TSH response, but mice with thyrotrope-specific disruption of Isl1 have a blunted TSH response. In contrast, deletion of Isl1 in gonadotropes with an Lhb-cre transgene has no obvious effect on gonadotrope function or fertility. These results show that ISL1 is necessary for maximal thyrotrope response to hypothyroidism, in addition to its role in development of Rathke's pouch.

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Rue, Sarah M., Sara Mattei, Suraj Saksena, and Scott D. Emr. "Novel Ist1-Did2 Complex Functions at a Late Step in Multivesicular Body Sorting." Molecular Biology of the Cell 19, no. 2 (February 2008): 475–84. http://dx.doi.org/10.1091/mbc.e07-07-0694.

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In Saccharomyces cerevisiae, integral plasma membrane proteins destined for degradation and certain vacuolar membrane proteins are sorted into the lumen of the vacuole via the multivesicular body (MVB) sorting pathway, which depends on the sequential action of three endosomal sorting complexes required for transport. Here, we report the characterization of a new positive modulator of MVB sorting, Ist1. We show that endosomal recruitment of Ist1 depends on ESCRT-III. Deletion of IST1 alone does not cause cargo-sorting defects. However, synthetic genetic analysis of double mutants of IST1 and positive modulators of MVB sorting showed that ist1Δ is synthetic with vta1Δ and vps60Δ, indicating that Ist1 is also a positive component of the MVB-sorting pathway. Moreover, this approach revealed that Ist1-Did2 and Vta1-Vps60 compose two functional units. Ist1-Did2 and Vta1-Vps60 form specific physical complexes, and, like Did2 and Vta1, Ist1 binds to the AAA-ATPase Vps4. We provide evidence that the ist1Δ mutation exhibits a synthetic interaction with mutations in VPS2 (DID4) that compromise the Vps2-Vps4 interaction. We propose a model in which the Ist1-Did2 and Vta1-Vps60 complexes independently modulate late steps in the MVB-sorting pathway.

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Barzelay, Aya, Jeremy Ben-Shoshan, Michal Entin-Meer, Sofia Maysel-Auslender, Arnon Afek, Iris Barshack, Gad Keren, and Jacob George. "A potential role for islet-1 in post-natal angiogenesis and vasculogenesis." Thrombosis and Haemostasis 103, no. 01 (2010): 188–97. http://dx.doi.org/10.1160/th09-07-0433.

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SummaryThe LIM-homeobox transcription factor islet-1 (Isl1) marks a cell population which gives rise to myocardial, pacemaker, endothelial and smooth muscle cells, which are derived from the secondary heart field during heart embryogenesis. Isl1+ precursors have the potential of self-renewal and differentiation into endothelial, cardiomyocyte and smooth muscle lineages. The primary objective of this study was to determine whether retroviral gene delivery of Isl1 to endothelial cells and mesenchymal stem cells (MSCs) could promote angiogenic and vasculogenic properties. To this end, endothelial cells and rat MSCs were retrovirally transduced to express Isl1. Isl1 expression in endothelial cells resulted in enhanced proliferation and adhesion to fibronectin. In addition, increased IL-1b and VEGF secretion was evident in Isl1 transduced endothelial cells, concomitant with increased migratory and tube formation properties of the endothelial cells. Isl1 expression in MSCs promoted their vasculogenic properties and resulted in enhanced in vitro tube formation. Finally, Isl1 expressing endothelial cells induced enhanced in vivo vascularisation in C57BL/6J mice. These data suggest, for the first time, that Isl1 promotes postnatal angiogenesis and vasculogenesis by improving the angiogenic properties of endothelial cells and MSCs.

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Zhou, Yunhe, Hua Yang, Jiahao Shi, Mengjie Zhang, Sai Yang, Ning Wang, Ruilin Sun, Zhugang Wang, and Jian Fei. "Fate Tracing of Isl1+Cells in Adult Mouse Hearts under Physiological and Exercise Conditions." International Journal of Sports Medicine 40, no. 14 (October 15, 2019): 921–30. http://dx.doi.org/10.1055/a-0961-1458.

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AbstractMyocardial damage due to dysfunctional myocardium has been increasing, and the prognosis of pharmacological and device-based therapies remain poor. Isl1-expressing cells were thought to be progenitor cells for cardiomyocyte proliferation after specific stimuli. However, the true origin of the proliferating myocardiac cells and the role of Isl1 in adult mammals remain unresolved. In this study, Isl1-CreERT2 knock-in mouse model was constructed using CRISPR/Cas9 technology. Using tamoxifen-inducible Isl1-CreERT/Rosa26R-LacZ system, Isl1+cells and their progeny were permanently marked by lacZ-expression. X-gal staining, immunostaining, and quantitative PCR were then used to reveal the fate of Isl1+cells under physiological and exercise conditions in mouse hearts from embryonic stage to adulthood. Isl1+cells were found to localize to the sinoatrial node, atrioventricular node, cardiac ganglia, aortic arch, and pulmonary roots in adult mice heart. However, they did not act as cardiac progenitor cells under physiological and exercise conditions. Although Isl1+cells showed progenitor cell properties in early mouse embryos (E7.5), this ability was lost by E9.5. Furthermore, although the proliferation and regeneration of heart cell was observed in response to exercise, the cells associated were not Isl1 positive.

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Zhao, Meng, Niels Banhos Danneskiold-Samsøe, Laetitia Voilquin, Zewen Jiang, and Katrin J. Svensson. "LBMON185 Isthmin-1 As A Modulator Of Metabolic Health." Journal of the Endocrine Society 6, Supplement_1 (November 1, 2022): A587. http://dx.doi.org/10.1210/jendso/bvac150.1216.

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Abstract Insulin resistance involves impaired glucose clearance capacity by the skeletal muscle and adipose tissue and is also associated with muscle loss. However, the underlying mechanistic link between diabetes and muscle loss is not well understood. Here, we identify Isthmin-1 (Ism1) as a secreted signaling protein with multi-organ actions. By performing untargeted phosphoproteomics revealing the global signaling actions of Ism1, we identify that Ism1 stimulates adipose and skeletal muscle glucose uptake and an increase in skeletal muscle protein synthesis. Mechanistically, Ism1 activates pAKT-mTOR-S6 signaling independently of insulin or the insulin receptor. In mice, Ism1 ablation results in impaired glucose clearance capacity and reduced insulin sensitivity, demonstrating an endogenous function for Ism1 in systemic glucose regulation. Notably, the administration of recombinant Ism1 is sufficient to ameliorate diabetes in a diet-induced obese mouse model. Ism1 ablation also results in smaller skeletal muscle fiber size and lower muscle protein content, demonstrating that Ism1 is required for muscle proteostasis. These findings reveal a new secreted protein hormone that activates anabolic pathways in muscle and adipose tissue. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

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Seo, So Yeon, Bora Lee, and Seunghee Lee. "Critical Roles of the LIM Domains of Lhx3 in Recruiting Coactivators to the Motor Neuron-Specifying Isl1-Lhx3 Complex." Molecular and Cellular Biology 35, no. 20 (August 10, 2015): 3579–89. http://dx.doi.org/10.1128/mcb.00335-15.

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During spinal cord development, the LIM domains of the LIM homeodomain factor Lhx3 bind to either the LIM cofactor nuclear LIM interactor (NLI) or another LIM homeodomain factor, Isl1, assembling the tetrameric V2 interneuron-specifying Lhx3 complex (2NLI:2Lhx3) or the hexameric motor neuron-specifying Isl1-Lhx3 complex (2NLI:2Isl1:2Lhx3). However, the detailed molecular basis by which the Lhx3-LIM domains contribute to motor neuron specification still remains poorly understood. Here, we show that the Lhx3-LIM domains are essential for recruiting transcriptional coactivators to the Isl1-Lhx3 complex. Using a yeast genetic screening system, we identify Lhx3 point mutants that bind to NLI but not Isl1. Accordingly, these mutants fail to assemble the Isl1-Lhx3 complex. However, their interaction with coactivators is relatively intact, and they are fully functional in the Lhx3 complex and V2 interneuron specification. Interestingly, when these Lhx3 mutants are directly fused to Isl1, their transcriptional activity in the Isl1-Lhx3 complex is restored. We further show that this restoration reflects an unexpected role of the Lhx3-LIM domains, likely together with Isl1, to form an interaction interface for coactivators. Our results suggest that the Lhx3-LIM domains play critical roles in transactivation of the Isl1-Lhx3 complex by not only directing the assembly of the Isl1-Lhx3 complex but also recruiting coactivators to the complex.

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Osório, Liliana, Xuewei Wu, Linsheng Wang, Zhixin Jiang, Carlos Neideck, Guojun Sheng, and Zhongjun Zhou. "ISM1 regulates NODAL signaling and asymmetric organ morphogenesis during development." Journal of Cell Biology 218, no. 7 (June 6, 2019): 2388–402. http://dx.doi.org/10.1083/jcb.201801081.

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Isthmin1 (ISM1) was originally identified as a fibroblast group factor expressed in Xenopus laevis embryonic brain, but its biological functions remain unclear. The spatiotemporal distribution of ISM1, with high expression in the anterior primitive streak of the chick embryo and the anterior mesendoderm of the mouse embryo, suggested that ISM1 may regulate signaling by the NODAL subfamily of TGB-β cytokines that control embryo patterning. We report that ISM1 is an inhibitor of NODAL signaling. ISM1 has little effect on TGF-β1, ACTIVIN-A, or BMP4 signaling but specifically inhibits NODAL-induced phosphorylation of SMAD2. In line with this observation, ectopic ISM1 causes defective left-right asymmetry and abnormal heart positioning in chick embryos. Mechanistically, ISM1 interacts with NODAL ligand and type I receptor ACVR1B through its AMOP domain, which compromises the NODAL–ACVR1B interaction and down-regulates phosphorylation of SMAD2. Therefore, we identify ISM1 as an extracellular antagonist of NODAL and reveal a negative regulatory mechanism that provides greater plasticity for the fine-tuning of NODAL signaling.

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Bajorek, Monika, Eiji Morita, Jack J. Skalicky, Scott G. Morham, Markus Babst, and Wesley I. Sundquist. "Biochemical Analyses of Human IST1 and Its Function in Cytokinesis." Molecular Biology of the Cell 20, no. 5 (March 2009): 1360–73. http://dx.doi.org/10.1091/mbc.e08-05-0475.

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The newly described yeast endosomal sorting complexes required for transport (ESCRT) protein increased sodium tolerance-1 (Ist1p) binds the late-acting ESCRT proteins Did2p/charged MVB protein (CHMP) 1 and Vps4p and exhibits synthetic vacuolar protein sorting defects when combined with mutations in the Vta1p/LIP5–Vps60p/CHMP5 complex. Here, we report that human IST1 also functions in the ESCRT pathway and is required for efficient abscission during HeLa cell cytokinesis. IST1 binding interactions with VPS4, CHMP1, LIP5, and ESCRT-I were characterized, and the IST1–VPS4 interaction was investigated in detail. Mutational and NMR spectroscopic studies revealed that the IST1 terminus contains two distinct MIT interacting motifs (MIM1 and MIM2) that wrap around and bind in different groves of the MIT helical bundle. IST1, CHMP1, and VPS4 were recruited to the midbodies of dividing cells, and depleting either IST1 or CHMP1 proteins blocked VPS4 recruitment and abscission. In contrast, IST1 depletion did not inhibit human immunodeficiency virus-1 budding. Thus, IST1 and CHMP1 act together to recruit and modulate specific VPS4 activities required during the final stages of cell division.

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Shen, Qingtang, Nissrine Beyrouthy, Laura Matabishi-Bibi, and Catherine Dargemont. "The chromatin remodeling Isw1a complex is regulated by SUMOylation." Biochemical Journal 474, no. 20 (October 5, 2017): 3455–69. http://dx.doi.org/10.1042/bcj20170172.

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The ISWI class of proteins consists of a family of chromatin remodeling ATPases that is ubiquitous in eukaryotes and predominantly functions to slide nucleosomes laterally. The yeast Saccharomyces cerevisiae Isw1 partners with several non-essential alternative subunits — Ioc2, Ioc3, or Ioc4 — to form two distinct complexes Isw1a and Isw1b. Besides its ATPase domain, Isw1 presents a C-terminal region formed by HAND, SANT, and SLIDE domains responsible for interaction with the Ioc proteins and optimal association of Isw1 to chromatin. Despite diverse studies on the functions of the Isw1-containing complexes, molecular evidence for a regulation of this chromatin remodeling ATPase is still elusive. Results presented here indicate that Isw1 is not only ubiquitylated but also strongly SUMOylated on multiple lysine residues by the redundant Siz1/Siz2 SUMO E3 ligases. However, Isw1 is a poor substrate of the Ulp1 and Ulp2 SUMO proteases, thus resulting in a high level of modification. Extensive site-directed mutagenesis allowed us to identify the major SUMOylation sites and develop a SUMO-defective mutant of Isw1. Using this molecular tool, we show that SUMOylation of Isw1 specifically facilitates and/or stabilizes its interaction with its cofactor Ioc3 and consequently the efficient recruitment of the Isw1–Ioc3 complex onto chromatin. Together these data reveal a new regulatory mechanism for this fascinating remodeling factor.

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Thibessard, Annabelle, Annabelle Fernandez, Brigitte Gintz, Bernard Decaris, and Nathalie Leblond-Bourget. "Transposition of pGh9:ISS1 is random and efficient in Streptococcus thermophilus CNRZ368." Canadian Journal of Microbiology 48, no. 5 (May 1, 2002): 473–78. http://dx.doi.org/10.1139/w02-038.

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Streptococcus thermophilus bacteria are used as a starter in the fermentation of yogurts and many cheeses. To construct mutants of S. thermophilus CNRZ368, the use of the plasmid pGh9:ISS1 was considered. This plasmid is known to be a good tool for insertional mutagenesis in gram-positive bacteria, owing to its ability to integrate in the genome by a mechanism of replicative transposition. However, the presence of three endogenous ISS1 copies in the genome of S. thermophilus CNRZ368 and the possible occurrence of homologous recombination could reduce the efficiency of pGh9:ISS1 as a tool for generating mutants. To address this question, the ability of pGh9:ISS1 to transpose randomly in the genome of strain CNRZ368 was investigated. The results of our experiments indicated that: (i) the frequency of transposition of ISS1 was high, approximately 2 × 102, in S. thermophilus CNRZ368; (ii) the integration of multiple tandem copies of the plasmid was frequent; (iii) homologous recombination events between ISS1 were not predominant; and (iv) plasmid pGh9:ISS1 transposed randomly around the S. thermophilus CNRZ368 chromosome. In addition, we describe the strategy used to localize the pGh9:ISS1 insertion locus on the physical map of strain CNRZ368 and the method used to clone the regions flanking this insertion site, especially when multiple copies of the plasmid were integrated in tandem.Key words: insertional mutagenesis, random transposition, Streptococcus thermophilus, homologue recombination, ISS1.

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Wang, Ying, Jing-Wen Wang, Yang Li, Xiao-Hui Tian, Xin-Shun Feng, Shu-Cong Zhang, Pei-Jun Liu, Wu-Jun Xue, Jin Zheng, and Xiao-Ming Ding. "Bone Marrow-Derived Mesenchymal Stem Cells Improve Rat Islet Graft Revascularization by Upregulating ISL1." Stem Cells 39, no. 8 (April 3, 2021): 1033–48. http://dx.doi.org/10.1002/stem.3378.

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Abstract Revascularization of the islet transplant is a crucial step that defines the success rate of patient recovery. Bone marrow-derived mesenchymal stem cells (BMSCs) have been reported to promote revascularization; however, the underlying cellular mechanism remains unclear. Moreover, our liquid chromatography-tandem mass spectrometry results showed that BMSCs could promote the expression of insulin gene enhancer binding protein-1 (ISL1) in islets. ISL1 is involved in islets proliferation and plays a potential regulatory role in the revascularization of islets. This study identifies the ISL1 protein as a potential modulator in BMSCs-mediated revascularization of islet grafts. We demonstrated that the survival rate and insulin secretion of islets were increased in the presence of BMSCs, indicating that BMSCs promote islet revascularization in a coculture system and rat diabetes model. Interestingly, we also observed that the presence of BMSCs led to an increase in ISL1 and vascular endothelial growth factor A (VEGFA) expression in both islets and the INS-1 rat insulinoma cell line. In silico protein structure modeling indicated that ISL1 is a transcription factor that has four binding sites with VEGFA mRNA. Further results showed that overexpression of ISL1 increased both the abundance of VEGFA transcripts and protein accumulation, while inhibition of ISL1 decreased the abundance of VEGFA. Using a ChIP-qPCR assay, we demonstrated that direct molecular interactions between ISL1 and VEGFA occur in INS-1 cells. Together, these findings reveal that BMSCs promote the expression of ISL1 in islets and lead to an increase in VEGFA in islet grafts. Hence, ISL1 is a potential target to induce early revascularization in islet transplantation.

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Sahiri, Virgilia, Jonathan Caron, Elena Roger, Christophe Desterke, Khalil Ghachem, Inna Mohamadou, Justine Serre, et al. "The Angiogenesis Inhibitor Isthmin-1 (ISM1) Is Overexpressed in Experimental Models of Glomerulopathy and Impairs the Viability of Podocytes." International Journal of Molecular Sciences 24, no. 3 (February 1, 2023): 2723. http://dx.doi.org/10.3390/ijms24032723.

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Focal segmental glomerulosclerosis (FSGS) is a major cause of end-stage renal disease and remains without specific treatment. To identify new events during FSGS progression, we used an experimental model of FSGS associated with nephroangiosclerosis in rats injected with L-NAME (Nω-nitro-L-arginine methyl ester). After transcriptomic analysis we focused our study on the role of Isthmin-1 (ISM1, an anti-angiogenic protein involved in endothelial cell apoptosis. We studied the renal expression of ISM1 in L-NAME rats and other models of proteinuria, particularly at the glomerular level. In the L-NAME model, withdrawal of the stimulus partially restored basal ISM1 levels, along with an improvement in renal function. In other four animal models of proteinuria, ISM1 was overexpressed and localized in podocytes while the renal function was degraded. Together these facts suggest that the glomerular expression of ISM1 correlates directly with the progression-recovery of the disease. Further in vitro experiments demonstrated that ISM1 co-localized with its receptors GRP78 and integrin αvβ5 on podocytes. Treatment of human podocytes with low doses of recombinant ISM1 decreased cell viability and induced caspase activation. Stronger ISM1 stimuli in podocytes dropped mitochondrial membrane potential and induced nuclear translocation of apoptosis-inducing factor (AIF). Our results suggest that ISM1 participates in the progression of glomerular diseases and promotes podocyte apoptosis in two different complementary ways: one caspase-dependent and one caspase-independent associated with mitochondrial destabilization.

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Álvarez-Hernán, Guadalupe, Ruth Bejarano-Escobar, Ruth Morona, Agustín González, Gervasio Martín-Partido, and Javier Francisco-Morcillo. "Islet-1 Immunoreactivity in the Developing Retina ofXenopus laevis." Scientific World Journal 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/740420.

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The LIM-homeodomain transcription factor Islet1 (Isl1) has been widely used as a marker of neuronal differentiation in the developing visual system of different classes of vertebrates, including mammals, birds, reptiles, and fish. In the present study, we analyzed the spatial and temporal distribution of Isl1-immunoreactive cells duringXenopus laevisretinal development and its relation to the formation of the retinal layers, and in combination with different markers of cell differentiation. The earliest Isl1 expression appeared at St29-30 in the cell nuclei of sparse differentiating neuroblasts located in the vitreal surface of the undifferentiated retina. At St35-36, abundant Isl1-positive cells accumulated at the vitreal surface of the neuroepithelium. As development proceeded and through the postmetamorphic juveniles, Isl1 expression was identified in subpopulations of ganglion cells and in subsets of amacrine, bipolar, and horizontal cells. These data together suggest a possible role for Isl1 in the early differentiation and maintenance of different retinal cell types, and Isl1 can serve as a specific molecular marker for the study of retinal cell specification inX. laevis.

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Fu, Rongdian, and Gerrit Voordouw. "ISD1, an Insertion Element from the Sulfate-Reducing Bacterium Desulfovibrio vulgaris Hildenborough: Structure, Transposition, and Distribution." Applied and Environmental Microbiology 64, no. 1 (January 1, 1998): 53–61. http://dx.doi.org/10.1128/aem.64.1.53-61.1998.

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ABSTRACT Insertion element ISD1, discovered when its transposition caused the insertional inactivation of an introducedsacB gene, is present in two copies in the genome ofDesulfovibrio vulgaris Hildenborough. Southern blot analysis indicated at least two insertion sites in the sacBgene. Cloning and sequencing of a transposed copy of ISD1indicated a length of 1,200 bp with a pair of 44-bp imperfect inverted repeats at the ends, flanked by a direct repeat of the 4-bp target sequence. AAGG and AATT were found to function as target sequences. ISD1 encodes a transposase from two overlapping open reading frames by programmed translational frameshifting at an A6G shifty codon motif. Sequence comparison showed that ISD1 belongs to the IS3 family. Isolation and analysis of the chromosomal copies, ISD1-A and ISD1-B, by PCR and sequencing indicated that these are not flanked by direct repeats. ISD1-A is inserted in a region of the chromosome containing the gapdh-pgk genes (encoding glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase). Active transposition to other loci in the genome was demonstrated, offering the potential of a new tool for gene cloning and mutagenesis. ISD1 is the first transposable element described for the sulfate reducers, a large and environmentally important group of bacteria. The distribution of ISD1 in genomes of sulfate-reducing bacteria is limited. A single copy is present in the genome of D. desulfuricans Norway.

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Uzarska, Marta A., Rafal Dutkiewicz, Sven-Andreas Freibert, Roland Lill, and Ulrich Mühlenhoff. "The mitochondrial Hsp70 chaperone Ssq1 facilitates Fe/S cluster transfer from Isu1 to Grx5 by complex formation." Molecular Biology of the Cell 24, no. 12 (June 15, 2013): 1830–41. http://dx.doi.org/10.1091/mbc.e12-09-0644.

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The mitochondrial Hsp70 chaperone Ssq1 plays a dedicated role in the maturation of iron–sulfur (Fe/S) proteins, an essential process of mitochondria. Similar to its bacterial orthologue HscA, Ssq1 binds to the scaffold protein Isu1, thereby facilitating dissociation of the newly synthesized Fe/S cluster on Isu1 and its transfer to target apoproteins. Here we use in vivo and in vitro approaches to show that Ssq1 also interacts with the monothiol glutaredoxin 5 (Grx5) at a binding site different from that of Isu1. Grx5 binding does not stimulate the ATPase activity of Ssq1 and is most pronounced for the ADP-bound form of Ssq1, which interacts with Isu1 most tightly. The vicinity of Isu1 and Grx5 on the Hsp70 chaperone facilitates rapid Fe/S cluster transfer from Isu1 to Grx5. Grx5 and its bound Fe/S cluster are required for maturation of all cellular Fe/S proteins, regardless of the type of bound Fe/S cofactor and subcellular localization. Hence Grx5 functions as a late-acting component of the core Fe/S cluster (ISC) assembly machinery linking the Fe/S cluster synthesis reaction on Isu1 with late assembly steps involving Fe/S cluster targeting to dedicated apoproteins.

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Pavlik, Ivo, Petra Svastova, Jiri Bartl, Lenka Dvorska, and Ivan Rychlik. "Relationship between IS901 in theMycobacterium avium Complex Strains Isolated from Birds, Animals, Humans, and the Environment and Virulence for Poultry." Clinical Diagnostic Laboratory Immunology 7, no. 2 (March 1, 2000): 212–17. http://dx.doi.org/10.1128/cdli.7.2.212-217.2000.

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ABSTRACT A total of 738 strains of Mycobacterium avium complex (MAC) were examined in biological experiments on poultry by use of PCR methods with primers for detection of the insertion sequence IS901. Serotype strains of MAC from all known 28 serotypes were examined. Further strains were isolated from human immunodeficiency virus (HIV)-negative and HIV-positive patients, 6 animal species, 17 bird species, and the environment. Of 165 strains virulent for poultry, characterized by generalized tuberculosis, 164 strains contained IS901, a result which is statistically highly significant (P, 0.01). The remaining 573 strains were nonvirulent; however, IS901 was present in 24 strains. From among 20 strains of serotypes 1, 2, and 3, IS901 was found in 15 strains, only 5 of which were virulent for poultry. The remaining 111 strains, of serotypes 4 to 28, were nonvirulent and did not incorporate IS901. None of the 152 strains isolated from humans was virulent for poultry, including 12 strains which were IS901 positive.

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Galloway, Jamie R., Maigen Bethea, Yanping Liu, Rachel Underwood, James A. Mobley, and Chad S. Hunter. "SSBP3 Interacts With Islet-1 and Ldb1 to Impact Pancreatic β-Cell Target Genes." Molecular Endocrinology 29, no. 12 (December 1, 2015): 1774–86. http://dx.doi.org/10.1210/me.2015-1165.

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Abstract Islet-1 (Isl1) is a Lin11, Isl1, Mec3 (LIM)-homeodomain transcription factor important for pancreatic islet cell development, maturation, and function, which largely requires interaction with the LIM domain-binding protein 1 (Ldb1) coregulator. In other tissues, Ldb1 and Isl1 interact with additional factors to mediate target gene transcription, yet few protein partners are known in β-cells. Therefore, we hypothesize that Ldb1 and Isl1 participate in larger regulatory complexes to impact β-cell gene expression. To test this, we used cross-linked immunoprecipitation and mass spectrometry to identify interacting proteins from mouse β-cells. Proteomic datasets revealed numerous interacting candidates, including a member of the single-stranded DNA-binding protein (SSBP) coregulator family, SSBP3. SSBPs potentiate LIM transcription factor complex activity and stability in other tissues. However, nothing was known of SSBP3 interaction, expression, or activity in β-cells. Our analyses confirmed that SSBP3 interacts with Ldb1 and Isl1 in β-cell lines and in mouse and human islets and demonstrated SSBP3 coexpression with Ldb1 and Isl1 pancreas tissue. Furthermore, β-cell line SSBP3 knockdown imparted mRNA deficiencies similar to those observed upon Ldb1 reduction in vitro or in vivo. This appears to be (at least) due to SSBP3 occupancy of known Ldb1-Isl1 target promoters, including MafA and Glp1r. This study collectively demonstrates that SSBP3 is a critical component of Ldb1-Isl1 regulatory complexes, required for expression of critical β-cell target genes.

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Ahmad, F., S. N. Hisham, S. N. Yusof, M. S. Ahmad, N. A. Hasan, A. A. Hassan, N. L. Sukiran, et al. "Heterosis analysis of F₁ progenies derived from IS21 × MR220CL2 and IS21 × UKMRC16 crossing combinations." IOP Conference Series: Earth and Environmental Science 1208, no. 1 (July 1, 2023): 012036. http://dx.doi.org/10.1088/1755-1315/1208/1/012036.

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Abstract A new high-yielding mutant rice cultivar, IS21, has been released by the Malaysian Nuclear Agency (MNA) in 2021. This cultivar matures in 105-108 days after transplanting. Since there is a need to reduce days to maturity (DTM) in most Malaysian rice mega-varieties to minimise the impacts of abiotic and biotic stresses, crossing IS21 with early maturing rice genotypes could be an efficient strategy to address these issues. Preliminary screening has successfully identified two early maturing and shorter plant statue rice genotypes, MR220CL2 and UKMRC16. Therefore, these rice genotypes were crossed to IS21 to generate two F1 populations. These F1 populations (IS21 × MR220CL2 and IS21 × UKMRC16) were planted in the MNA glasshouse with parental lines from December 2021 to March 2022. The agro-morphological data for F1 populations and parental lines were recorded and analysed using the RStudio software package. The putative F1 progenies were confirmed using two polymorphic simple sequence repeat (SSR) SSR markers, RM628 and RM140. About 75% of the putative F1 are F1 hybrids. IS21 × MR220CL2 F1 progenies showed better morpho-agronomical performances compared to IS21 × UKMRC16 F1 progenies. This crossing combination also had positive mid-parents and better parent heterosis values of all evaluated traits except for thousand-grain weight, days to flowering and DTM. This study suggested the potential use of IS21 x MR220CL2 F1 progenies for rice breeding programmes with high-yielding and early maturity traits.

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Hao, Aijun, Veronica Novotny-Diermayr, Wei Bian, Baohong Lin, Cheh Peng Lim, Naihe Jing, and Xinmin Cao. "The LIM/Homeodomain Protein Islet1 Recruits Janus Tyrosine Kinases and Signal Transducer and Activator of Transcription 3 and Stimulates Their Activities." Molecular Biology of the Cell 16, no. 4 (April 2005): 1569–83. http://dx.doi.org/10.1091/mbc.e04-08-0664.

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Islet1 (Isl1) belongs to the LIM homeodomain transcription factor family. Its roles in differentiation of motor neurons and organogenesis of pancreas and heart have been revealed. However, less is known about its regulatory mechanism and the target genes. In this study, we identified interactions between Isl1 and Janus tyrosine kinase (JAK), as well as signal transducer and activator of transcription (Stat)3, but not Stat1 and Stat5, in mammalian cells. We found that Isl1 not only forms a complex with Jak1 and Stat3 but also triggers the tyrosine phosphorylation of Jak1 and its kinase activity, thereby elevating the tyrosine phosphorylation, DNA binding activity, and target gene expression of Stat3. In vivo, the tyrosine-phosphorylated Stat3 was colocalized with Isl1 in the nucleus of the mouse motor neurons in spinal cord after nerve injury. Correspondingly, electroporation of Isl1 and Stat3 into the neural tube of chick embryos resulted in the activation of a reporter gene expression controlled by a Stat3 regulatory sequence, and cotransfection of Isl1 and Stat3 promoted the proliferation of the mouse motor neuron cells. Our data suggest a novel role of Isl1 as an adaptor for Jak1 and Stat3 and reveal a possible functional link between LIM homeodomain transcription factors and the Jak-Stat pathway.

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MU, Tianchi, Tao WANG, Zhenyu GAO, Xin PAN, and Yingxue LIU. "Role of miR-128/216a Regulating Isl1 Expression during Differentiation of Human Umbilical Cord Mesenchymal Stem Cells into Insulin-Producing Cells." Wuhan University Journal of Natural Sciences 28, no. 2 (April 2023): 177–84. http://dx.doi.org/10.1051/wujns/2023282177.

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Islet-1 (Isl1), a LIM homeodomain protein, is expressed in the embryonic pancreatic epithelium. As a key transcription factor, Isl1 can not only regulate insulin gene expression in normal glucose condition but also maintain β-cell function and impact pancreatic β-cell target genes. Some experiments have suggested that MicroRNA (miRNA) can play a critical role during the induction of insulin-producing cells (IPCs). However, it is unclear whether miRNA may regulate Isl1 expression during differentiation of human umbilical cord mesenchymal stem cells (HUMSCs) into IPCs. In this investigation, we induced HUMSCs into IPCs with a modified two-step protocol, activin A, retinoic acid (step1) and conophylline, nicotinamide (step2). To find the miRNA regulating Isl1 expression, we respectively used TargetScan, miRDB and RNAhybrid to predict and got the result, miR-128 and miR-216a. The miRNAs can inhibit Isl1 expression by dual luciferase assay. The results of real-time Polymerase Chain Reaction (PCR) showed that Isl1 expression level was almost reciprocal to that of miR-128 and miR-216a during differentiation of HUMSCs into IPCs. Furthermore, over-expression of miR-128 or miR-216a down-regulated expression levels of Isl1 and MafA. Therefore, miR-128 or miR-216a may regulate expression of islet-specific transcription factors to control differentiation of HUMSCs into IPCs.

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Yin, Xiu-Yun, Huan-Xin Chen, Zhuo Chen, Qin Yang, Jun Han, and Guo-Wei He. "Genetic Variants of ISL1 Gene Promoter Identified from Congenital Tetralogy of Fallot Patients Alter Cellular Function Forming Disease Basis." Biomolecules 13, no. 2 (February 13, 2023): 358. http://dx.doi.org/10.3390/biom13020358.

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Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease in newborns. ISL1 is a master transcription factor in second heart field development, whereas the roles of ISL1 gene promoter variants in TOF patients have not been genetically investigated. Total DNA extraction from 601 human subjects, including 308 TOF patients and 293 healthy controls, and Sanger sequencing were performed. Four variants (including one novel heterozygous variant) within the ISL1 gene promoter were only found in TOF patients. Functional analysis of DNA sequence variants was performed by using the dual-luciferase reporter assay and demonstrated that three of the four variants significantly decreased the transcriptional activity of ISL1 gene promoter in HL-1 cells (p < 0.05). Further, the online JASPAR database and electrophoretic mobility shift assay showed that the three variants affected the binding of transcription factors and altered ISL1 expression levels. In conclusion, the current study for the first time demonstrated that the variants identified from the ISL1 gene promoter region are likely involved in the development of TOF by affecting the transcriptional activity and altering the ISL1 expression level. Therefore, these findings may provide new insights into the molecular etiology and potential therapeutic strategy of TOF.

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Zheng, Si-Qiang, Huan-Xin Chen, Xiao-Cheng Liu, Qin Yang, and Guo-Wei He. "Identification of variants of ISL1 gene promoter and cellular functions in isolated ventricular septal defects." American Journal of Physiology-Cell Physiology 321, no. 3 (September 1, 2021): C443—C452. http://dx.doi.org/10.1152/ajpcell.00167.2021.

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Ventricular septal defects (VSDs) are the most common congenital heart defects (CHDs). Studies have documented that ISL1 has a crucial impact on cardiac growth, but the role of variants in the ISL1 gene promoter in patients with VSD has not been explored. In 400 subjects (200 patients with isolated and sporadic VSDs: 200 healthy controls), we investigated the ISL1 gene promoter variant and performed cellular functional experiments by using the dual-luciferase reporter assay to verify the impact on gene expression. In the ISL1 promoter, five variants were found only in patients with VSD by sequencing. Cellular functional experiments demonstrated that three variants decreased the transcriptional activity of the ISL1 promoter ( P < 0.05). Further analysis with the online JASPAR database demonstrated that a cluster of putative binding sites for transcription factors may be altered by these variants, possibly resulting in change of ISL1 protein expression and VSD formation. Our study has, for the first time, identified novel variants in the ISL1 gene promoter region in the Han Chinese patients with isolated and sporadic VSD. In addition, the cellular functional experiments, electrophoretic mobility shift assay, and bioinformatic analysis have demonstrated that these variants significantly alter the expression of the ISL1 gene and affect the binding of transcription factors, likely resulting in VSD. Therefore, this study may provide new insights into the role of the gene promoter region for a better understanding of genetic basis of the formation of CHDs and may promote further investigations on mechanism of the formation of CHDs.

Journal articles on the topic 'Is91'

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