A novel member of the glycosyltransferase family, beta 3Gn-T2, highly downregulated in invasive human bladder transitional cell carcinomas

Differential display reverse transcription (DDRT)-polymerase chain reaction (PCR) was used to compare the transcriptomes of invasive and noninvasive f resh human bladder transitional cell carcinomas. A differentially expressed novel gene sharing structural similarity with the human beta3-galactosyltr ansferase family, beta -1,3-N-acetylglucosaminyltransferase-T2 (beta 3Gn-T2 ), was identified. The full-length beta 3Gn-T2 cDNA, containing a complete open reading frame of 1193 bp, was cloned and sequenced. beta 3Gn-T2 exhibi ted 29-41% homology to the multigene beta3-galactosyltransferase family. Ex pression of the full-length beta 3Gn-T2 cDNA in an in vitro coupled transcr iption/translation assay yielded a primary translation product with an appa rent Mr of 46 kDa, which is in agreement with the predicted 397-amino-acid protein encoded by beta 3Gn-T2. Multiple peptide alignment showed several s equence motifs corresponding to putative catalytic domains that are conserv ed throughout all members of the beta3-galactosyltransferase family, namely , a type II transmembrane domain, a conserved DxD motif, an N-glycosylation site, and five conserved cysteins. By RT-PCR strong downregulation of beta 3Gn-T2 expression was noted in invasive human bladder transitional cell ca rcinomas (16 fresh biopsy samples: grade III, T2-T4) compared with their no ninvasive counterparts (15 fresh biopsies: grade II, Ta), suggesting that b eta 3Gn-T2 may be involved in cancer progression. (C) 2001 Wiley-Liss, Inc.