Expression of UDP-<i>N</i>-acetyl-D-galactosamine: Polypeptide <i>N</i>-acetylgalactosaminyltransferase-6 in Gastric Mucosa, Intestinal Metaplasia, and Gastric Carcinoma

Gomes, Joana; Marcos, Nuno T.; Berois, Nora; Osinaga, Eduardo; Magalhães, Ana; Pinto-de-Sousa, João; Almeida, Raquel; Gärtner, Fátima; Reis, Celso A.

doi:10.1369/jhc.2008.952283

Cited by 62 publications

(47 citation statements)

References 49 publications

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“…The repertoire of enzyme isoforms expressed in cancer cells is markedly altered from the normal counterparts (29)(30)(31)(32)(33)(34); however, the consequences of these changes for the O-glycoproteome and carcinogenesis remain unknown. The locus 9q22 including the GALNT12 gene is a susceptibility locus for colorectal cancer (35) and heterozygous germ line as well as somatic inactivating mutations have been identified in cancer patients (36).…”

Section: Discussionmentioning

confidence: 99%

Probing isoform-specific functions of polypeptide GalNAc-transferases using zinc finger nuclease glycoengineered SimpleCells

Schjoldager

Vakhrushev²,

Kong³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

120

124

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Our knowledge of the O-glycoproteome [N-acetylgalactosamine (GalNAc) type] is highly limited. The O-glycoproteome is differentially regulated in cells by dynamic expression of a subset of 20 polypeptide GalNAc-transferases (GalNAc-Ts), and methods to identify important functions of individual GalNAc-Ts are largely unavailable. We recently introduced SimpleCells, i.e., human cell lines made deficient in O-glycan extension by zinc finger nuclease targeting of a key gene in Oglycan elongation (Cosmc), which allows for proteome-wide discovery of O-glycoproteins. Here we have extended the SimpleCell concept to include proteome-wide discovery of unique functions of individual GalNAc-Ts. We used the GalNAc-T2 isoform implicated in dyslipidemia and the human HepG2 liver cell line to demonstrate unique functions of this isoform. We confirm that GalNAc-T2-directed site-specific Oglycosylation inhibits proprotein activation of the lipase inhibitor ANGPTL3 in HepG2 cells and further identify eight O-glycoproteins exclusively glycosylated by T2 of which one, ApoC-III, is implicated in dyslipidemia. Our study supports an essential role for GalNAc-T2 in lipid metabolism, provides serum biomarkers for GalNAc-T2 enzyme function, and validates the use of GALNT gene targeting with SimpleCells for broad discovery of disease-causing deficiencies in O-glycosylation. The presented glycoengineering strategy opens the way for proteome-wide discovery of functions of GalNAc-T isoforms and their role in congenital diseases and disorders.apolipoproteins | angiopoietin-like proteins | genetic engineering | glycoproteins T he GALNT2 gene involved in O-glycosylation has been associated with aberrant serum levels of triglyceride (TG) and highdensity lipoprotein cholesterol (HDL-C) by several genome-wide association studies (GWAS) (1, 2). A direct functional role of this gene was obtained by transient knockdown and overexpression of galnt2 in mouse liver, which resulted in increased and lowered plasma HDL-C, respectively (3). GALNT2 is a member of the largest family of homologous glycosyltransferase isoforms (up to 20) catalyzing the same glycosidic linkage (GalNAcα1-O-Ser/Thr) and initiating protein O-glycosylation (4, 5). These isoforms have overlapping but distinct peptide substrate specificities and identifying essential unique functions for individual GalNAc-T isoforms has been notoriously difficult. In search of putative functions of GALNT2 in lipid metabolism, we previously screened a number of known and predicted O-glycoproteins with roles in lipid metabolism for O-glycosylation by the encoded GalNAc-T2 enzyme and identified ANGPTL3 (6). We found that site-specific O-glycosylation of a Thr residue adjacent to the proprotein convertase (PC) processing site in ANGPTL3 that activates this lipase inhibitor was performed only by the GalNAc-T2 isoform. More recently, a heterozygous mutation in GALNT2 resulting in slightly reduced kinetic properties of the encoded GalNAc-T2 enzyme was found in two probands with elevated HDL and reduced TG (7). ...

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Section: Discussionmentioning

confidence: 99%

Probing isoform-specific functions of polypeptide GalNAc-transferases using zinc finger nuclease glycoengineered SimpleCells

Schjoldager

Vakhrushev²,

Kong³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

120

124

View full text Add to dashboard Cite

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“…The percentage was higher in intestinal and diffuse type carcinomas (81% and 86%). In the precancerous state of intestinal metaplasia the percentage presence dropped to 52% [9]. This may reflect the differentiation traits of the tissue.…”

Section: Role In Cancermentioning

confidence: 94%

“…pp-GalNAc-T6 has been associated with venous invasion in gastric carcinomas, in the body of the stomach [9]. It is expressed in 79% of gastric carcinomas tested in comparison to 69% in normal gastric mucosa.…”

Section: Role In Cancermentioning

confidence: 99%

“…This may reflect the differentiation traits of the tissue. pp-GalNAc-T6 has been suggested as a marker to predict venous invasion in gastric carcinoma [9].…”

Section: Role In Cancermentioning

confidence: 99%

“…Like other family members, pp-GalNAc-T6 resides on the lumen side of the membrane of the Golgi apparatus [1,[9][10][11]. It is a type II membrane protein, in which its N-terminal tail spans the Golgi membrane [12].…”

Section: Introductionmentioning

confidence: 99%

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UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase- 6 (pp-GalNAc-T6): Role in Cancer and Prospects as a Drug Target

Banford¹,

Timson

2016

CCDT

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UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyl transferase-6 (pp-GalNAc-T6) is a member of the N-acetyl-D-galactosamine transferase family. It catalyzes the addition of N-acetyl-D-galactosamine to proteins, often the first step in Oglycosylation of proteins. Glycosylated proteins play important roles in vivo in the cell membrane. These are often involved in cell-cell adhesion, cytoskeleton regulation and immune recognition. pp-GalNAc-T6 has been shown to be upregulated in a number of types of cancer. Abnormally glycosylated forms of mucin 1 (substrate of the enzyme), are used clinically as a biomarker for breast cancer. There is potential for other products of the pp-GalNAc-T6 catalyzed reaction to be used. It is also possible that pp-GalNAc-T6 itself could be used as a biomarker, since levels of this protein tend to be low in nonmalignant tissues. pp-GalNAc-T6 has been implicated in malignant transformation and metastasis of cancer cells. As such, it has considerable potential as a target for chemotherapy. To date, no selective inhibitors of the enzyme have been identified. However, general inhibitors of the enzyme family result in reduced cell surface Olinked glycosylation and induce apoptosis in cultured cells. Thus, a selective inhibitor of pp-GalNAc-T6 is likely to target cancer cells and could be developed into a novel anticancer therapy.

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GALNT14 mediates tumor invasion and migration in breast cancer cell MCF‐7

Tian

Zuo

Wang

et al. 2014

Molecular Carcinogenesis

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Aberrant glycosylation is a hallmark of most human cancers and affects many cellular properties, including cell proliferation, apoptosis, differentiation, transformation, migration, invasion, and immune responses. Here, we report that N-acetylgalactosaminyltransferase14 (GALNT14), which mediates the initial step of mucin-type O-glycosylation and is heterogeneously expressed in most breast cancers, plays a critical role in the invasion and migration of breast cancers by regulating the activity of MMP-2 and expression of some EMT genes. We have modulated the expression of GALNT14 by RNAi and overexpression in MCF-7 cells. Overexpression of GALNT14 significantly enhanced cell migration and invasion and promoted the proliferation of breast cancer cells. Knockdown of GALNT14 reduced clonogenicity and attenuates cell migration and cell invasion. The mRNAs for N-cadherin, vimentin, E-cadherin, MMP-2, VEGF, and TGF-β were determined by RT-qPCR involving GALNT14-overexpressing or knockdown MCF-7 cells. Expression profiling revealed the upregulation of N-cadherin, vimentin, MMP-2, VEGF, TGF-β and the downregulation of E-cadherin in GALNT14 overexpressing cells, with the opposite seen in GALNT14 knockdowns. Gelatin zymography analysis further indicated that overexpression of GALNT14 increased MMP-2 activity in MCF-7 cells. Conversely, downregulation of GALNT14 reduced MMP-2 activity. Promoter analysis revealed that GALNT14 stimulates MMP-2 expression through the AP-1-binding site. Western blot analyses showed that knockdown of GALNT14 significantly reduced the expression of an oncoprotein mucin 1 (MUC1). These findings indicate that GALNT14 contributes to breast cancer invasion by altering the cell proliferation, motility, expression levels of EMT genes, and by stimulating MMP-2 activity, suggesting GALNT14 may be a potential target for breast cancer treatment.

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Expression of UDP-N-acetyl-D-galactosamine: Polypeptide N-acetylgalactosaminyltransferase-6 in Gastric Mucosa, Intestinal Metaplasia, and Gastric Carcinoma

Cited by 62 publications

References 49 publications

Probing isoform-specific functions of polypeptide GalNAc-transferases using zinc finger nuclease glycoengineered SimpleCells

Probing isoform-specific functions of polypeptide GalNAc-transferases using zinc finger nuclease glycoengineered SimpleCells

UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase- 6 (pp-GalNAc-T6): Role in Cancer and Prospects as a Drug Target

GALNT14 mediates tumor invasion and migration in breast cancer cell MCF‐7

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