Abstract
Spalax, a subterranean blind mole rat, is well adapted to live in an extreme hypoxic environment through up-regulated expression of growth factors and enzymes for ensuring sufficient oxygen supply. One of the overexpressed enzymes is heparanase, an endoglucuronidase that selectively cleaves heparan sulfate (HS) and is implicated in angiogenesis. To assess the implications of the heparanase in Spalax, we have characterized the structure of HS isolated from various organs of the animal. The oligosaccharides obtained after deaminative cleavage of HS samples from the tissues show an overall higher sulfation degree, distinct from that of murine tissues. Of particular significance was the appearance of a trisaccharide moiety in the tissues examined, apart of the even numbered oligosaccharide fractions typically found in HS from human and mouse tissues. The formation of this odd-numbered saccharide is a consequence of heparanase action, in agreement with the notion of high expression of the enzyme in this species. Analysis of HS extracted from human embryonic kidney cells (HEK293) after exposure to hypoxic condition revealed a structural change in the distribution of oligosaccharides similar to HS derived from Spalax organs. The alterations are likely due to up-regulated activity of heparanase, as real-time RT-PCR showed a 2-fold increase in heparanase mRNA expression in the hypoxia treated cells. HEK293 cells stably overexpressing Spalax heparanase produced HS sharing similarity with that from the Spalax organs, and exhibited enhanced MAPK activity in comparison with HEK293 cells, indicating a regulation role of the heparanase in the activity of growth factors.
Highlights
The blind subterranean mole rat Spalax ehrenbergi is a fossorial mammal, which spends its entire life in sealed under
To explore the correlation between hypoxia, heparanase, and heparan sulfate (HS) structure, we examined HS from HEK293 cells that stably expresses Spalax heparanase in comparison with mock-transfected cells and found that overexpression of Spalax heparanase in HEK293 cells resulted in a HS structure similar to that of HS extracted from the Spalax organs, while overexpression of human heparanase in the same cells did not produce the trisaccharide fraction, suggesting a different enzymatic action of two heparanase species
The diversity of HS structure is by large the result of a regulated biosynthesis, two additional enzymes, endosulfatases and heparanase, play important roles in regulation of HS structure postsynthesis [16, 26]
Summary
Of particular significance was the appearance of a trisaccharide moiety in the tissues examined, apart of the even numbered oligosaccharide fractions typically found in HS from human and mouse tissues The formation of this odd-numbered saccharide is a consequence of heparanase action, in agreement with the notion of high expression of the enzyme in this species. Though the established biochemical function of heparanase is to catalyze the degradation of HS, this degrading property of heparanase regulates several processes of physiological and pathological importance This enzyme plays significant roles in morphogenesis and development as well as in matrix remodeling [10, 11] and was shown to be involved in cell invasion associated with angiogenesis, inflammation, and cancer metastasis [12,13,14,15]. The effect of Spalax heparanase on cellular activity was evaluated by measuring Erk phosphorylation in MAPK signaling pathway
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
