Involvement of heparan sulfate proteoglycan in sensing hypotonic stress in bovine aortic endothelial cells.
Hypotonic stress (HTS) induces various responses in vascular endothelium, but the molecules involved in sensing HTS are not known. To investigate a possible role of heparan sulfate proteoglycan (HSPG) in sensing HTS, we compared the responses of control bovine aortic endothelial cells (BAECs) with those of cells treated with heparinase III, which exclusively degrades HSPG. Tyrosine phosphorylation of 125 kDa FAK induced by HTS (-30%) in control cells was abolished in heparinase III-treated BAECs. The amplitude of the volume-regulated anion channel (VRAC) current, whose activation is regulated by tyrosine kinase, was significantly reduced by the treatment with heparinase III. Also, HTS-induced ATP release through the VRAC pore and the concomitant Ca(2+) transients were significantly reduced in the heparinase III-treated BAECs. In contrast, exogenously applied ATP evoked similar Ca(2+) transients in both control and heparinase III-treated BAECs. The transient formation of actin stress fibers induced by HTS in control cells was absent in heparinase III-treated BAECs. Lysophosphatidic acid (LPA) also induced FAK phosphorylation, actin reorganization and ATP release in control BAECs, but heparinase III did not affect these LPA-induced responses. We conclude from these observations that HSPG is one of the sensory molecules of hypotonic cell swelling in BAECs.
Oike
Masahiro
M
Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan. moike@pharmaco.med.kyushu-u.ac.jp
Watanabe
Michi
M
Kimura
Chiwaka
C
D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000166:cytology* / Q000201:enzymology; D020013:Calcium Signaling / Q000187:drug effects; D002417:Cattle; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism*; D007038:Hypotonic Solutions / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011133:Polysaccharide-Lyases / Q000378:metabolism
D000199:Actins; D019812:Heparan Sulfate Proteoglycans; D007038:Hypotonic Solutions; D007473:Ion Channels; D008246:Lysophospholipids; D019000:Phosphotyrosine; D000255:Adenosine Triphosphate; D051417:Focal Adhesion Kinase 1; D011133:Polysaccharide-Lyases; C021349:heparitinsulfate lyase; C032881:lysophosphatidic acid