Lack of L-iduronic acid in heparan sulfate affects interaction with growth factors and cell signaling
2009 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 284, no 23, 15942-15950 p.Article in journal (Refereed) Published
Glucuronyl C5-epimerase (Hsepi) catalyzes the conversion of D-glucuronic acid to L-iduronic acid in heparan sulfate (HS) biosynthesis. Disruption of the Hsepi gene in mouse yielded a lethal phenotype with selective organ defects, but had remarkably little effect on other organ systems. We have approached the underlying mechanisms by examining the course and effects of FGF2 signaling in a mouse embryonic fibroblast (MEF) cell line derived from the Hsepi-/- mouse. The HS produced by these cells is devoid of IdoA residues, but shows upregulated N- and 6-O-sulfation compared to wildtype (WT) MEF HS. In medium fortified with 10% FCS the Hsepi-/- MEFs proliferated and migrated similar to WT cells. Under starvation conditions both cell types showed attenuated proliferation and migration, that could be restored by addition of FGF2 to WT cells whereas Hsepi-/- cells were resistant. Moreover, ERK phosphorylation following FGF2 stimulation was delayed in Hsepi-/- compared to WT cells. Assessment of HS-growth factor interaction by nitrocellulose filter trapping revealed strikingly aberrant binding property of FGF2 and glia-derived neurotropic factor (GDNF) to Hsepi-/- but not to WT HS. GDNF has a key role in kidney development, defective in Hsepi-/- mice. By contrast, Hsepi-/- and WT HS interacted similarly and in conventional mode with FGF10. These findings correlate defective function of growth factors with their mode of HS interaction, and may help explain the partly modest organ phenotypes observed after genetic ablation of selected enzymes in HS biosynthesis.
Place, publisher, year, edition, pages
2009. Vol. 284, no 23, 15942-15950 p.
IdentifiersURN: urn:nbn:se:uu:diva-103525DOI: 10.1074/jbc.M809577200ISI: 000266501000061PubMedID: 19336402OAI: oai:DiVA.org:uu-103525DiVA: diva2:218389