Heparan sulfate (HS) is a complex linear polysaccharide that modulates a wide range of biological functions. Elucidating the structure-function relationship of HS has been challenging. Here we report the generation of a HS mutant mouse lung endothelial cell library by systematic deletion of HS genes expressing in the cell. We applied this library to answer several fundamental questions about HS biology including: 1) determining that strictly defined fine structure of HS, not its overall sulfation degree, is more important for FGF2-FGFR1 signaling; 2) defining the epitope features of commonly used anti-HS phage display antibodies; and 3) delineating the fine inter-regulation networks of HS modification and chain length by HS genes in mammalian cells and at a cell type specific level. Our mutant cell library will enable robust and systematic interrogation of the roles and related structures of HS in a cellular context.

Helicobacter pylori exploits host glycoconjugates to colonize the gastric niche. Infection can persist for decades promoting chronic inflammation, and in a subset of individuals lesions can silently progress to cancer. This study shows that H. pylori chronic infection and gastric tissue inflammation result in a remodeling of the gastric glycophenotype with increased expression of sialyl-Lewis a/x antigens due to transcriptional up-regulation of the B3GNT5, B3GALT5, and FUT3 genes. We observed that H. pylori infected individuals present a marked gastric local proinflammatory signature with significantly higher TNF-α levels and demonstrated that TNF-induced activation of the NF-kappaB pathway results in B3GNT5 transcriptional up-regulation. Furthermore, we show that this gastric glycosylation shift, characterized by increased sialylation patterns, favors SabA-mediated H. pylori attachment to human inflamed gastric mucosa. This study provides novel clinically relevant insights into the regulatory mechanisms underlying H. pylori modulation of host glycosylation machinery, and phenotypic alterations crucial for life-long infection. Moreover, the biosynthetic pathways here identified as responsible for gastric mucosa increased sialylation, in response to H. pylori infection, can be exploited as drug targets for hindering bacteria adhesion and counteract the infection chronicity.

Background: Glycans contribute to vertebrate development, but regulatory mechanisms are unknown. Results: Glycans and transcripts encoding the glycosylation machinery were profiled during stem cell differentiation. Conclusion: Changes in glycans frequently correlated with changes in transcripts, supporting a significant role for transcriptional regulation. Significance: Knowledge of the mechanisms that regulate glycan expression provides insight into the roles of glycosylation in development.

Background Proteoglycans are found on the cell surface and in the extracellular matrix, and serve as prime sites for interaction with signaling molecules. Proteoglycans help regulate pathways that control stem cell fate, and therefore represent an excellent tool to manipulate these pathways. Despite their importance, there is a dearth of data linking glycosaminoglycan structure within proteoglycans with stem cell differentiation. Methods Human embryonic stem cell line WA09 (H9) was differentiated into early mesoderm and endoderm lineages, and the glycosaminoglycanomic changes accompanying these transitions were studied using transcript analysis, immunoblotting, immunofluorescence and disaccharide analysis. Results Pluripotent H9 cell lumican had no glycosaminoglycan chains whereas in splanchnic mesoderm lumican was glycosaminoglycanated. H9 cells have primarily non-sulfated heparan sulfate chains. On differentiation towards splanchnic mesoderm and hepatic lineages N-sulfo group content increases. Differences in transcript expression of NDST1, HS6ST2 and HS6ST3, three heparan sulfate biosynthetic enzymes, within splanchnic mesoderm cells compared to H9 cells correlate to changes in glycosaminoglycan structure. Conclusions Differentiation of embryonic stem cells markedly change the proteoglycanome General Significance The glycosaminoglycan biosynthetic pathway is complex and highly regulated, and therefore, understanding the details of this pathway should enable better control with the aim of directing stem cell differentiation.

Quantitative real-time polymerase chain reaction (qRT-PCR) is a flexible and scalable method for analyzing transcript abundance that can be used at a single gene or high-throughput (>100 genes) level. Information obtained from this technique can be used as an indicator of potential regulation of glycosylation at the transcript level when combined with glycan structural or protein abundance data. This chapter describes detailed methods to design and perform qRT-PCR analyses and provides examples of information that can be obtained from the technique.