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.
Two natural homogalacturonan (HG) pectins (MW
ca. 20 kDa) were isolated from green tea based on their immunomodulatory activity. The crude tea polysaccharides (TPS1 and TPS2) were obtained from green tea leaves by hot water extraction and followed by 40% and 70% ethanol precipitation, respectively. Two homogenous water soluble polysaccharides (TPS1-2a and TPS1-2b) were obtained from TPS1 after purification with gel permeation, which gave a higher phagocytic effect than TPS2. A combination of composition, methylation and configuration analyses, as well as NMR (nuclear magnetic resonance) spectroscopy revealed that TPS1-2a and TPS1-2b were homogalacturonan (HG) pectins consisting of a backbone of 1,4-linked α-d-galacturonic acid (GalA) residues with 28.4% and 26.1% of carboxyl groups as methyl ester, respectively. The immunological assay results demonstrated that TPS1-2, which consisted mainly of HG pectins, showed phagocytosis-enhancing activity in HL-60 cells.
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