We attempted to determine whether ␤1,3-galactosyltransferase ␤3Gal-T5 is involved in the biosynthesis of a specific subset of type 1 chain carbohydrates and expressed in a cancer-associated manner. We transfected Chinese hamster ovary (CHO) cells expressing Fuc-TIII with ␤3Gal-T cDNAs and studied the relevant glycoconjugates formed. ␤3Gal-T5 directs synthesis of Lewis type 1 antigens in CHO cells more efficiently than ␤3Gal-T1, whereas ␤3Gal-T2, -T3, and -T4 are almost unable to direct synthesis. In the clone expressing Fuc-TIII and ␤3Gal-T5 (CHO-FT-T5), sialyl-Lewis a synthesis is strongly inhibited by swainsonine but not by benzyl-␣-GalNAc, and sialyl-Lewis x is absent, although it is detected in the clones expressing Fuc-TIII and ␤3Gal-T1 (CHO-FT-T1) or Fuc-TIII and ␤3Gal-T2 (CHO-FT-T2). Endo-␤-galactosidase treatment of Nglycans prepared from clone CHO-FT-T5 releases (؎NeuAc␣233)Gal␤133[Fuc␣134]GlcNAc␤133Gal but not GlcNAc␤133Gal or type 2 chain oligosaccharides, which are found in CHO-FT-T1 cells. This result indicates that ␤3Gal-T5 expression prevents poly-Nacetyllactosamine and sialyl-Lewis x synthesis on Nglycans. Kinetic studies confirm that ␤3Gal-T5 prefers acceptors having the GlcNAc␤133Gal end, including lactotriosylceramide. Competitive reverse transcriptase mediated-polymerase chain reaction shows that the ␤3Gal-T5 transcript is expressed in normal colon mucosa but not or poorly in adenocarcinomas. Moreover, recombinant carcinoembryonic antigen purified from a CHO clone expressing Fuc-TIII and ␤3Gal-T5 reacts with anti-sialyl-Lewis a and carries type 1 chains on oligosaccharides released by endo-␤-galactosidase. We conclude that ␤3Gal-T5 down-regulation plays a relevant role in determining the cancer-associated glycosylation pattern of N-glycans.Type 1 chain oligosaccharides found in N-and O-glycans, as well as in glycolipids, contain the distinctive Gal␤133GlcNAc disaccharide as their core structure. It is synthesized by ␤1,3-galactosyltransferases (

DNA ligase I-deficient 46BR.1G1 cells show a delay in the maturation of replicative intermediates resulting in the accumulation of single- and double-stranded DNA breaks. As a consequence the ataxia telangiectasia mutated protein kinase (ATM) is constitutively phosphorylated at a basal level. Here, we use 46BR.1G1 cells as a model system to study the cell response to chronic replication-dependent DNA damage. Starting from a proteomic approach, we demonstrate that the phosphorylation level of factors controlling constitutive and alternative splicing is affected by the damage elicited by DNA ligase I deficiency. In particular, we show that SRSF1 is hyperphosphorylated in 46BR.1G1 cells compared to control fibroblasts. This hyperphosphorylation can be partially prevented by inhibiting ATM activity with caffeine. Notably, hyperphosphorylation of SRSF1 affects the subnuclear distribution of the protein and the alternative splicing pattern of target genes. We also unveil a modulation of SRSF1 phosphorylation after exposure of MRC-5V1 control fibroblasts to different exogenous sources of DNA damage. Altogether, our observations indicate that a relevant aspect of the cell response to DNA damage involves the post-translational regulation of splicing factor SRSF1 which is associated with a shift in the alternative splicing program of target genes to control cell survival or cell death.

Colour polymorphism occurs when two or more genetically-based colour morphs permanently coexist within an interbreeding population. Colouration is usually associated to other life-history traits (ecological, physiological, behavioural, reproductive …) of the bearer, thus being the phenotypic marker of such set of genetic features. This visual badge may be used to inform conspecifics and to drive those decision making processes which may contribute maintaining colour polymorphism under sexual selection context. The importance of such information suggests that other communication modalities should be recruited to ensure its transfer in case visual cues were insufficient. Here, for the first time, we investigated the potential role of proteins from femoral gland secretions in signalling colour morph in a polymorphic lizard. As proteins are thought to convey identity-related information, they represent the ideal cues to build up the chemical modality used to badge colour morphs. We found strong evidence for the occurrence of morph-specific protein profiles in the three main colour-morphs of the common wall lizard, which showed both qualitative and quantitative differences in protein expression. As lizards are able to detect proteins by tongue-flicking and vomeronasal organ, this result support the hypothesis that colour polymorphic lizards may use a multimodal signal to inform about colour-morph.