Academic literature on the topic 'B4GALNT3'

<b><i>Background:</i></b> Altered plasma activity of β-1,4-galac­tosyl­transferases (B4GALTs) is a novel candidate biomarker of human aging. B4GALT1 is assumed to be largely responsible for this activity increase, but how it modulates the aging process is unclear at present. <b><i>Objectives:</i></b> To determine how expression of B4GALT1 and other B4GALT enzymes changes during aging of an experimentally tractable model organism, <i>Caenorhabditis elegans</i>. <b><i>Methods:</i></b> Targeted analysis of mRNA levels of all 3 <i>C. elegans</i> B4GALT family members was performed by qPCR in wild-type and in long-lived <i>daf-2</i> (insulin/IGF1-like receptor)-deficient or germline-deficient animals. <b><i>Results:</i></b> <i>bre-4</i> (<i>B4GALT1/2/3/4</i>) is the only B4GALT whose expression increases during aging in wild-type worms. In addition, <i>bre-4</i> levels also rise during aging in long-lived <i>daf-2</i>-deficient worms, but not in animals that are long-lived due to the lack of germline stem cells. On the other hand, expression of <i>sqv-3 (B4GALT7)</i> and of <i>W02B12.11 (B4GALT5/6)</i> appears decreased or constant, respectively, in all backgrounds during aging. <b><i>Conclusions:</i></b> The age-dependent <i>bre-4</i> mRNA increase in <i>C. elegans</i> parallels the age-dependent B4GALT activity increase in humans and is consistent with <i>C. elegans</i> being a suitable experimental organism to define potentially conserved roles of B4GALT1 during aging.

Abstract β1,4-galactosyltransferase 4 (B4GalT4) is one of seven B4GalTs that belong to CAZy glycosyltransferase family 7 and transfer galactose to growing sugar moieties of proteins, glycolipids, glycosaminoglycans as well as single sugar for lactose synthesis. Herein, we identify two asparagine-linked glycosylation sites in B4GalT4. We found that mutation of one site (Asn220) had greater impact on enzymatic activity while another (Asn335) on Golgi localization and presence of N-glycans at both sites is required for production of stable and enzymatically active protein and its secretion. Additionally, we confirm B4GalT4 involvement in synthesis of keratan sulfate (KS) by generating A375 B4GalT4 knock-out cell lines that show drastic decrease in the amount of KS proteoglycans and no significant structural changes in N- and O-glycans. We show that KS decrease in A375 cells deficient in B4GalT4 activity can be rescued by overproduction of either partially or fully glycosylated B4GalT4 but not with N-glycan-depleted B4GalT4 version.

Growth differentiation factor-10 (GDF10) with its methylation trait has recently been found to play a crucial regulatory and communication role in cancers. This investigation aims to identify GDF10 methylation site-associated genes that are closely associated with endometrial cancer (EC) patients’ survival based on normal and UCEC samples from the UCSC Xena database. Our study revealed for the first time that EC exhibited significantly higher levels of GDF10 promoter methylation in comparison with normal tissues. Multiple differentiated methylation sites, which have prognostic value due to their apparent survival differences, were found in the GDF10 promoter region. We performed weighted gene coexpression network analysis (WGCNA) on EC tissues and paraneoplastic tissues while using these differentially methylated sites as phenotypes for selecting the most correlated key modules and their internal genes. To obtain a gene set, the key module genes and differentially expressed genes (DEGs) of EC were intersected. The least absolute shrinkage and selection operator (LASSO) regression along with multivariate Cox regression were performed from the gene set and we screened out the key genes B4GALNT3, DNAJC22, and GREB1. Finally, a prognostic model was validated for effectiveness based on these genes. Additionally, Kaplan-Meier analysis and time-dependent receiver operating characteristics (ROC) were applied to assess and verify the model, and they showed good prognosis prediction. Moreover, the differences in risk scores were statistically significant with age, tumor stage, and grade. They may be related to the immune infiltration of tumors as well. In conclusion, based on the methylation-related genes associated with GDF10, we developed a prognosis model for EC patients. It might provide a fresh view for further research and treatment of EC.

Background. Gangliosides act as important roles in tumor progression. B4GALNT1 is a key enzyme in ganglioside biosynthesis. B4GALNT1 expression is linked to tumorigenesis and the prognosis of tumor patients. Nevertheless, the role of B4GALNT1 in pan-cancer remains unclear. Methods. Several databases, including TCGA, GEO, GTEx, NCI-60, and TIMER, were searched. Methods including correlation analysis, Cox regression analysis, and Kaplan-Meier analysis were used to explore the expression pattern, prognosis, tumor infiltration pattern, genetics and epigenetics, and drug sensitivity of B4GALNT1 in pan-cancer patients from the above datasets. Results. B4GALNT1 was found to be aberrantly expressed in multiple types of tumors. The survival status of tumor patients was significantly related to B4GALNT1 expression, but the correlations were tumor-specific. Moreover, the expression of B4GALNT1 was associated with ImmuneScore and StromalScore in 21 and 27 tumor types, respectively. Also, B4GALNT1 was significantly associated with TMB, MSI, MMR, and DNA methylation. Additionally, the sensitivity of 9 drugs was correlated with the expression of B4GALNT1. Conclusion. A correlation of B4GALNT1 expression with prognosis exists in multiple types of cancers. In addition, B4GALNT1 expression may play a role in TME and tumor immunity regulation. Further investigation of the biological mechanisms of its different roles in tumorigenesis and clinical application as a biomarker is still required.

Background: The carbohydrate antigen Sda and its biosynthetic enzyme B4GALNT2 are highly expressed in normal colonic mucosa but are down-regulated to a variable degree in colon cancer tissues. Here, we investigated the clinical and biological importance of B4GALNT2 in colon cancer. Methods: Correlations of B4GALNT2 mRNA with clinical data were obtained from The Cancer Genome Atlas (TCGA) database; the phenotypic and transcriptomic changes induced by B4GALNT2 were studied in LS174T cells transfected with B4GALNT2 cDNA. Results: TCGA data indicate that patients with high B4GALNT2 expression in cancer tissues display longer survival than non-expressers. In LS174T cells, expression of B4GALNT2 did not affect the ability to heal a scratch wound or to form colonies in standard growth conditions but markedly reduced the growth in soft agar, the tridimensional (3D) growth as spheroids, and the number of cancer stem cells, indicating a specific effect of B4GALNT2 on the growth in poor adherence and stemness. On the transcriptome, B4GALNT2 induced the down-regulation of the stemness-associated gene SOX2 and modulated gene expression towards an attenuation of the cancer phenotype. Conclusions: The level of B4GALNT2 can be proposed as a marker to identify higher- and lower-risk colorectal cancer patients.

Background: glycosyltransferase B4GALNT2 and its cognate carbohydrate antigen Sda are highly expressed in normal colon but strongly downregulated in colorectal carcinoma (CRC). We previously showed that CRC patients expressing higher B4GALNT2 mRNA levels displayed longer survival. Forced B4GALNT2 expression reduced the malignancy and stemness of colon cancer cells. Methods: Kaplan–Meier survival curves were determined in “The Cancer Genome Atlas” (TCGA) COAD cohort for several glycosyltransferases, oncogenes, and tumor suppressor genes. Whole expression data of coding genes as well as miRNA and methylation data for B4GALNT2 were downloaded from TCGA. Results: the prognostic potential of B4GALNT2 was the best among the glycosyltransferases tested and better than that of many oncogenes and tumor suppressor genes; high B4GALNT2 expression was associated with a lower malignancy gene expression profile; differential methylation of an intronic B4GALNT2 gene position and miR-204-5p expression play major roles in B4GALNT2 regulation. Conclusions: high B4GALNT2 expression is a strong predictor of good prognosis in CRC as a part of a wider molecular signature that includes ZG16, ITLN1, BEST2, and GUCA2B. Differential DNA methylation and miRNA expression contribute to regulating B4GALNT2 expression during colorectal carcinogenesis.

The Sda carbohydrate epitope and its biosynthetic B4GALNT2 enzyme are expressed in the healthy colon and down-regulated to variable extents in colon cancer. The human B4GALNT2 gene drives the expression of a long and a short protein isoform (LF-B4GALNT2 and SF-B4GALNT2) sharing identical transmembrane and luminal domains. Both isoforms are trans-Golgi proteins and the LF-B4GALNT2 also localizes to post-Golgi vesicles thanks to its extended cytoplasmic tail. Control mechanisms underpinning Sda and B4GALNT2 expression in the gastrointestinal tract are complex and not fully understood. This study reveals the existence of two unusual N-glycosylation sites in B4GALNT2 luminal domain. The first atypical N-X-C site is evolutionarily conserved and occupied by a complex-type N-glycan. We explored the influence of this N-glycan using site-directed mutagenesis and showed that each mutant had a slightly decreased expression level, impaired stability, and reduced enzyme activity. Furthermore, we observed that the mutant SF-B4GALNT2 was partially mislocalized in the endoplasmic reticulum, whereas the mutant LF-B4GALNT2 was still localized in the Golgi and post-Golgi vesicles. Lastly, we showed that the formation of homodimers was drastically impaired in the two mutated isoforms. An AlphaFold2 model of the LF-B4GALNT2 dimer with an N-glycan on each monomer corroborated these findings and suggested that N-glycosylation of each B4GALNT2 isoform controlled their biological activity.

A new fecundity gene named the FecL (mutation), which regulates the ovulation rate, was discovered in French Lacaune sheep. The B4GALNT2 (beta-1, 4-N-acetyl-galactosaminyl transferase 2) gene was considered as the potential FecL mutation gene. This study explores whether the effect of the FecL mutation exists in other sheep breeds, and the features of the B4GALNT2 gene in terms of the molecular structure and its expression profile. Using Sanger sequencing, we found that high and low fecundity breeds from among 11 measured sheep breeds all had no variation in the three specific mutation sites, which were linked with the FecL mutation. However, two mutations of g.36946470C > T and g.36933082C > T in the exon of B4GALNT2 had a significant effect on litter size in the first parity for Small Tail Han (STH) Sheep (p < 0.05). Two transcription start sites (TSS) of B4GALNT2 in its 5′-flanking region were discovered in ovine granule cells in vitro, through the RACE (Rapid amplification of cDNA ends) method. Except for in the kidney and oviduct, no significant difference in expression levels had been found between STH sheep and Tan sheep breeds. The B4GALNT2 gene, as a candidate for FecL, may have a relationship with the differences in litter size in STH sheep. B4GALNT2 is mainly expressed in the ovine ovary, which also suggests that B4GALNT2 plays an important role in sheep reproduction.

2014 - 2015
Papillary thyroid carcinoma (PTC) is the most frequent thyroid malignant neoplasia. Oncogene activation occurs in more than 70% of the cases. BRAF mutations occur in about 40% of PTCs, whereas RET rearrangements (RET/PTC oncogenes) are present in about 20% of cases. Finally, RAS mutations and TRK and PPARG rearrangements account for about 5% each of these malignancies. However, despite the presence of tumor-initiating driver events, cancer results from the progressive accumulation of mutations in genes that confer growth advantage over surrounding cells. A better understanding of molecular alterations of PTC will provide important insights into cancer etiology. It will also lead to advance in their diagnosis, possibly opening the way for developing novel molecular therapies. Thus, the aim of this PhD project is to deeply explore the transcriptome of PTC in order to identify new driver events in this type of cancer. In the first part of this study, we used RNA-Sequencing in a discovery cohort of 18 patients with papillary thyroid carcinoma to identify fusion transcripts and expressed mutations in cancer driver genes. Furthermore, we used targeted sequencing on the DNA of these same patients to validate identified mutations. We extended the screening to thyroids of 50 PTC patients and of 30 healthy individuals. Using this approach we identified new somatic mutations in CBL, NOTCH1, PIK3R4 and SMARCA4 genes. We also found mutations in DICER, MET and VHL genes, previously found mutated in other tumors, but not described yet in PTC. We also identified a new chimeric transcript generated by the fusion of lysine deficient protein kinase 1 (WNK1) and beta-1,4-N-acetylgalactosaminyl transferase 3 (B4GALNT3) genes and correlated with an overexpression of B4GALNT3 gene. Moreover, although protein coding genes play a leading role in cancer genetics, in recent years, many studies focused on a novel class of non coding RNAs, long non coding RNAs (lncRNAs), which regulate the expression levels of protein coding genes. Since deregulated expression of lncRNAs has been reported in many cancers, it suggests that that they may act as potential oncogene or tumorsuppressor. Thus, to assess if lncRNAs can exert a tumorigenic role in thyroid, in the second part of my PhD project I systematically quantified lncRNAs’ expression in PTC vs healthy thyroids using our RNA-Seq data. Combining ab initio reconstruction to a custom computational pipeline we found that novel and known lncRNAs are significantly altered in PTC, and some of them are possibly associated with cancer driver genes. Then we extensively focused on an unannotated lncRNA transcribed antisense to MET oncogene, named in this study MET-AS. Both genes are significantly up-regulated in a sub-class of PTCs - i.e. patients with BRAF gene mutations and RET gene rearrangements, compared to other PTCs and "non-tumor" thyroid biopsies. Preliminary data indicate that MET-AS knockdown induces down-regulation of MET, and induces a changes in cell cycle in a PTC cell line, suggesting the novel lncRNA might be a new MET regulator. Further studies should be conducted to demonstrate detailed mechanism of our findings. Finally, our data confirmed the genetic heterogeneity of papillary thyroid carcinoma revealing that gene expression correlates more with the mutation pattern than with tumor staging. Overall, this study provides new information about PTC genetic alterations, suggesting potential pharmacological adjuvant therapies in PTC. [edited by author]
Il carcinoma papillare tiroideo (PTC) costituisce circa l’80% di tutti i tumori maligni della tiroide. Ad oggi, sono state identificate mutazioni a carico del gene BRAF in circa il 40% di casi, mentre riarrangiamenti che coinvolgono il gene RET (RET/PTC) sono presenti in circa il 20% dei casi. Infine, mutazioni nei geni RAS e riarrangiamenti dei geni TRK e PPARG occorrono in circa il 5% dei casi ciascuno. Tuttavia, nonostante la presenza di alterazioni genetiche che possano dare inizio al processo canceroso, il tumore è il risultato del progressivo accumulo di mutazioni in geni che conferiscono un vantaggio di crescita sulle cellule circostanti. Pertanto, una conoscenza più approfondita delle alterazioni molecolari del carcinoma papillare tiroideo è fondamentale per migliorare gli aspetti diagnostici e prognostici, e la risposta individuale ai trattamenti farmacologici. Alla luce di ciò, il mio progetto di dottorato ha avuto come obiettivo principale l’analisi del trascrittoma del PTC al fine di individuare nuovi eventi molecolari che possano essere implicati in questo tipo di cancro. La prima parte di questo progetto è stata focalizzata sul sequenziamento - mediante RNA-Seq – di 22 RNA isolati da biopsie di tiroide (18 tiroidi affette da carcinoma papillare tiroideo, 4 tiroidi non tumorali) per identificare trascritti di fusione e mutazioni somatiche in geni espressi. I risultati sono stati validati sul DNA dei medesimi pazienti mediante sequenziamento diretto di Sanger. Inoltre, l’analisi mutazionale è stata estesa ad ulteriori 50 pazienti affetti da carcinoma papillare tiroideo e 30 individui sani. Mediante quest’approccio sono state identificate nuove mutazioni puntiformi nei geni CBL, NOTCH1, PIK3R4 e SMARCA4. Inoltre, l’analisi ha rivelato la presenza di mutazioni somatiche nei geni DICER1, MET e VHL, già note nella patogenesi in altri tipi di cancro, ma ad oggi non note nel PTC. Inoltre, è stato individuato un nuovo evento di fusione intra-cromosomico generato dalla fusione tra il primo esone del gene WNK1 (lysine deficient protein kinase 1) e il secondo esone del gene B4GALNT3 (beta-1,4-N-acetyl-galactosaminyl transferase 3). I geni codificanti rivestono un ruolo di primo piano nella genetica del cancro, ma negli ultimi anni, molti studi si sono concentrati su una nuova classe di RNA non codificanti, i long non coding RNA (lncRNAs), che regolano l’espressione dei geni codificanti. I livelli di espressione dei lncRNA sono spesso alterati in diversi tipi di tumori, suggerendo che essi possano agire sia da oncogeni sia da oncosoppressori. Al fine di valutare il loro potenziale ruolo nella tumorigenesi del PTC, la seconda parte di questo progetto è stata focalizzata sull’analisi computazionale dei lncRNA, sia nuovi che annotati, nei nostri dataset di RNASeq. Attraverso l’utilizzo di approcci per la ricostruzione ab initio del trascrittoma e di una pipeline computazionale sono stati indentificati i lncRNA significativamente deregolati nei campioni tumorali. Inoltre, per individuare i lncRNA che potessero regolare l’espressione genica in cis, alcuni di essi sono stati associati - per vicinanza al TSS (transcription start site) - a geni driver in diversi tipi di cancro. Infine, mi sono focalizzata su un lncRNA non annotato nei database pubblici, associato all’oncogene MET, ma trascritto dal filamento opposto. Si tratta pertanto di un lncRNA antisenso al gene MET, chiamato in questo lavoro di tesi MET-AS. Entrambi i geni sono significativamente sovraespressi in una sotto-classe di PTC - vale a dire i pazienti con mutazioni del gene BRAF e riarrangiamenti dell’oncogene RET – chiamati BRAF-like-, rispetto ai campioni tumorali PTC, con profilo trascrizionale simile ai campioni mutati nei geni RAS – chiamati RAS-like - e campioni di tiroide "non-tumorali". Esperimenti preliminari condotti in vitro su una linea cellulare di carcinoma papillare tiroideo, TPC-1, indicano che il silenziamento del lncRNA MET-AS induce una down-regolazione dell’oncogene MET, e induce un blocco del ciclo cellulare in fase G1, suggerendo che il lncRNA potrebbe essere un nuovo regolatore dell’oncogene MET. In conclusione, i risultati ottenuti in questo lavoro di tesi confermano l'eterogeneità genetica del carcinoma papillare della tiroide rivelando che l'espressione genica correla più con il profilo mutazionale dei pazienti che con la stadiazione del tumore. Inoltre, questo studio fornisce nuove informazioni sulle alterazioni genetiche del PTC, suggerendo potenziali terapie adiuvanti farmacologiche per questo tipo di cancro. [a cura dell'autore]
XIV n.s.

L’objectif de cette thèse était d’identifier une mutation nommée FecLL affectant le nombre d’ovulations et la prolificité des brebis de race Lacaune et d’en analyser les conséquences physiologiques. En associant des approches de génétique et de biologie fonctionnelle à haut débit telles que le séquençage Roche 454 et la spectrométrie de masse, j’ai mis en évidence que la mutation FecLL est un haplotype de 2 SNPs présents dans des régions non-codantes d’un locus de 194,6kb porté par le chromosome 11 ovin. Cette mutation induit la surexpression ovarienne et l’activité du gène B4GALNT2 (beta-1,4-N-acetyl-galactosaminyl transferase 2) codant une enzyme de glycosylation capable de transférer un sucre N-acétyl-galactosamine sur des glycoprotéines cibles, dont l’inhibine A, une hormone importante pour la fonction ovarienne. Les conséquences de cette glycosylation atypique sont une altération de la production d’inhibine A chez les brebis Lacaune mutées, proposée comme mécanisme initiateur de leur hyper-prolificité
The aim of this thesis was to identify a mutation called FecLL affecting ovulation rate and prolificacy of Lacaune sheep and to study its physiological consequences. By combining genetics and functional highthroughput biology approaches such as Roche 454 sequencing and mass spectrometry, I evidenced the FecLL mutation as a 2 SNP haplotype present in non-coding regions of a 194.6 kb locus on ovine chromosome 11. This mutation induces ectopic overexpression and ovarian activity of the B4GALNT2 (beta-1,4-N-acetylgalactosaminyl transferase 2) gene encoding a glycosylation enzyme capable of transferring a N-acetylgalactosamine sugar on target glycoproteins. Among those targets, I highlighted inhibin A, an important hormone in ovarian function. The consequences of this atypical glycosylation lead to impaired production of inhibin A in Lacaune mutated sheep proposed as an initiator mechanism of their hyper- prolificacy

Le gène B4GALNT2 code l’enzyme β1,4-N-acétylgalactosaminyltransférase II qui contrôle l’expression de l’antigène glucidique de groupe sanguin Sda (GalNAcβ1,4[Neu5Acα2-3]Galβ1-4GlcNAc-R). Cet antigène glucidique est aussi détecté dans les tissus humains, principalement dans le tractus gastro-intestinal. Il est exprimé dans le côlon sain et tend à disparaître dans le côlon cancéreux, alors que l’antigène sLex (Neu5Acα2-3Galβ1-4[Fucα1-3]GlcNAc-R) normalement absent dans le côlon sain apparaît dans les cellules cancéreuses coliques. Cependant les mécanismes moléculaires permettant l’expression de l’antigène tumoral sLex au dépend de l’antigène Sda restent inconnus. Le gène B4GALNT2 gouverne l’expression de différents transcrits résultant de l’utilisation de deux sites d’initiation de la transcription différents localisés à 200 pb l’un de l’autre. L’utilisation alternative de deux premiers exons (E1s et E1L) conduit à la production de deux types de transcrits majoritaires, l’un court, l’autre long. Pour comprendre les mécanismes transcriptionnels qui régulent l’expression du gène B4GALNT2 dans le côlon, nous avons établi le profil d’expression du gène B4GALNT2 dans différentes lignées cellulaires et différents tissus humains par Q-PCR et nous avons entrepris une identification des régions génomiques régulatrices essentielles du gène B4GALNT2. La quantification relative de chaque type de transcrit indique que le transcrit court est le transcrit majoritairement exprimé dans les cellules coliques, dans le côlon et l’estomac dont l’expression diminue fortement dans le côlon cancéreux. Nous avons délimité une région minimale promotrice en transfectant transitoirement des constructions contenant différentes régions génomiques en amont du gène rapporteur de la luciférase, dans différentes lignées cellulaires, coliques saines ou non et gastriques. Des expériences de retard sur gel nous ont permis de mettre en évidence des complexes protéines-acide nucléique. Des sites de fixation potentiels pour des facteurs de transcription ont été déterminés par des analyses bioinformatiques de la région promotrice basale. La mutation de ces sites par mutagénèse dirigée nous a permis de déterminer l’implication de ces facteurs de transcription dans la régulation du gène B4GALNT2. Enfin, la fixation in cellulo de ces facteurs de transcription au niveau de la région promotrice minimale du gène B4GALNT2 a été confirmée par immunoprécipitation de la chromatine. Nos résultats suggèrent que le transcrit court du gène B4GALNT2 humain soit majoritairement exprimé dans le colon sain est régulé par un ensemble de facteurs de transcription tels que Ets-1, DMP1 ou Sp1
The B4GALNT2 gene encodes the β1,4-N-acetylgalactosaminyltransferase II enzyme that controls expression of the histo blood group antigen Sda (GalNAcβ1,4[Neu5Acα2-3]Galβ1-4GlcNAc-R). This carbohydrate antigen is detected in human tissues primarily in the gastrointestinal tract. It is expressed in healthy colon and tends to disappear in colon cancer, whereas the sLex antigen (Neu5Acα2-3Galβ1-4[Fucα1-3]GlcNAc-R) normally absent in healthy colon appears in colic cancer cells. However, molecular mechanisms underpinning expression of sLex tumor antigen at the expense of Sda antigen remain largely unknown. The B4GALNT2 gene drives the expression of several transcripts with alternative first exon named E1S (Short) and E1L (Long) arising from the use of two different transcriptional start sites located 200 bp apart from each other. To understand the transcriptional mechanisms that govern B4GALNT2 gene expression in colon, we have established the B4GALNT2 transcript expression profile in various cell lines and tissues using Q-PCR and we have undertaken an identification of essential regulatory genomic regions of the B4GALNT2 gene. The relative quantification of each transcript indicated that the short transcript variant of B4GALNT2 is the major transcript expressed in colic cells, and in colon and stomach, and is dramatically reduced in cancer colon. We report on the delineation of a minimal promoter region using transient cell expression of genomic deletion constructs harboring the luciferase reporter gene in healthy colic (or not) and gastriccell lines. Electrophoretic Mobility Shift Assay experiences allowed us to highlight protein-nucleic acid interactions in this minimal promoter region. Transcription factor binding sites were determined by bioinformatics analysis of the minimal promoter region. Mutation of these sites by directed mutagenesis allowed us to determine their implication in the regulation of the B4GALNT2 gene. Finally, in cellulo fixation of these transcription factors to the minimal promoter region of the B4GALNT2 gene was confirmed by chromatin immunoprecipitation. Our data further suggest that the short B4GALNT2 transcript is predominantly expressed in healthy colon and is regulated by a combination of various transcription factors such as Ets-1, DMP1 or Sp1

In colorectal cancer (CRC), two carbohydrate structures are modulated: the Sda antigen, synthesized by B4GALNT2, and sLex antigen, mainly synthesized by FUT6. sLex antigen is often overexpressed and associated with worse prognosis; B4GALNT2/Sda antigen are dramatically downregulated but their role in tumor progression and development is not fully clear. TCGA interrogation revealed a dramatic down-regulation of B4GALNT2 mRNA in CRC, compared with normal samples. Patients with higher B4GALNT2 mRNA in CRC samples displayed longer survival. Yet, methylation and miRNA expression play a relevant role in B4GALNT2 downregulation in CRC. To clarify the mechanisms linking the B4GALNT2/Sda expression level to CRC phenotype, three different CRC cell lines were modified to express B4GALNT2: LS174T cell line, in which the constitutively expressed sLex antigen was partially replaced by Sda; SW480/SW620 pair, both lacking Sda and sLex antigens. In LS174T cells, the expression of B4GALNT2 reduced the ability to grow in poor adherence conditions and the expression of ALDH, a stemness marker. In SW620 cells, B4GALNT2 expression impacted on the main aspects of malignancy. In SW480 cells the expression of B4GALNT2 left unchanged the proliferation rate and the wound healing ability. To clarify the impact of sLex on CRC phenotype, the SW480/SW620 pair were permanently transfected to express FUT6 cDNA. In both cell lines, overexpression of FUT6/sLex boosted the clonogenic ability in standard growth conditions. Conversely, the growth in soft agar and the capacity to close a wound were enhanced only in SW620 cells. Transcriptome analysis of CRC cell lines transfected either with B4GALNT2 or FUT6 showed a relevant impact of both enzymes on gene expression modulation. Overall, current data may help to personalize therapies for CRC patients according to the B4GALNT2 levels and support a causal effect of this glycosyltransferase on reducing malignancy independently of sLex inhibition.

碩士
臺灣大學
解剖學暨生物細胞學研究所
98
β-1,4-galactosyltransferases (B4GALTs) catalyze the transfer of UDP-galactose to an N-acetylglucosamine via β-1,4-linkage and are responsible for the biosynthesis of N-acetyllactosamine. Poly-N-acetyllactosamines are composed of repeating units of N-acetyllactosamine. In the present study, we elucidate the function of B4GALT3 in HCT116 colon cancer cells. Overexpression of B4GALT3 promotes cell proliferation in vitro and tumor growth in vivo, as well as colony formation. Overexpression of B4GALT3 also reduces cell migration and invasion. Interestingly, B4GALT3 increases poly-N-acetyllactosamine structures on both EGFR and β1 integrin. Up-regulation of phosphorylated EGFR (pY845) is found in cells overexpressing B4GALT3 and this may lead to an increase in cell growth. Moreover, B4GALT3 decreases phosphorylation of focal adhesion kinase (FAK) and paxillin, indicating that reduced cell migration may be partly mediated by integrin signaling pathways. Immunohistochemistry shows that B4GALT3 is up-regulated in 64.6% (7/11) of colorectal tumors compared with their normal counterparts, whereas only 40% (4/10) and 44.6% (37/83) detected by Western blotting and QPCR, respectively. This inconsistency may result from the positive staining of some stromal cells in colorectal mucosae.

This chapter further discusses bone dysplasias and includes discussion on achondrogenesis (type IB), atelosteogenesis type 2, diastrophic dysplasia, multiple epiphyseal dysplasia (recessive type [rMED]), Desbuquois dysplasia, chondrodysplasia with joint dislocations (IMPAD1/gPAPP type), Catel-Manzke syndrome, chondrodysplasia with congenital joint dislocations (CHST3-type), temtamy preaxial brachydactyly syndrome (TPBS), B4GALT7 deficiency, B3GAT3 deficiency, XYLT1 deficiency, spondyloepimetaphyseal dysplasia with joint laxity Beighton type, spondyloepimetaphyseal dysplasia with joint laxity (leptodactylic type), pseudodiastrophic dysplasia, and Steel syndrome. Each discussion includes major radiographic features, major clinical findings, genetics, major differential diagnoses, and a bibliography.