Hypoxia-induced mitogenic factor/FIZZ1 induces intracellular calcium release through the PLC-IP(3) pathway.
Hypoxia-induced mitogenic factor (HIMF), also known as "found in inflammatory zone 1" (FIZZ1) or resistin-like molecule-alpha (RELMalpha), is a profound vasoconstrictor of the pulmonary circulation and a strong mitogenic factor in pulmonary vascular smooth muscle. To further understand the mechanism of these contractile and mitogenic responses, we examined the effect of HIMF on intracellular Ca(2+) in human pulmonary artery smooth muscle cells (SMC). Ca(2+) imaging in fluo 4-loaded human pulmonary artery SMC revealed that recombinant murine HIMF increased intracellular Ca(2+) concentration ([Ca(2+)](i)) in a sustained and oscillatory manner. This increase occurred independent of extracellular Ca(2+) influx. Pretreatment of human pulmonary artery SMC with U-73122, a specific inhibitor of phosphatidylinositol-phospholipase C (PLC) completely prevented the HIMF-induced Ca(2+) signal. The [Ca(2+)](i) increase was also abolished by pretreatment with 2-aminoethoxydiphenyl borate (2-APB), an inositol 1,4,5-trisphosphate (IP(3)) receptor antagonist. Ryanodine pretreatment did not affect initiation of [Ca(2+)](i) activation or internal release but reduced [Ca(2+)](i) at the plateau phase. Pretreatment with the Galpha(i)-specific inhibitor pertussis toxin and the Galpha(s)-specific inhibitor NF-449 did not block the Ca(2+) signal. Knockdown of Galpha(q/11) expression did not prevent Ca(2+) release, but the pattern of Ca(2+) release changed from the sustained oscillatory transients with prolonged plateau to a series of short [Ca(2+)](i) transients that return to baseline. However, pretreatment with the tyrosine kinase inhibitor genistein completely inhibited the internal Ca(2+) release. These results demonstrate that HIMF can stimulate intracellular Ca(2+) release in human pulmonary artery SMC through the PLC signaling pathway in an IP(3)- and tyrosine phosphorylation-dependent manner and that Galpha(q/11) protein-coupled receptor and ryanodine receptor contribute to the increase of [Ca(2+)](i).
Dept. of Anesthesiology, Johns Hopkins Univ., Baltimore, MD 21205, USA.
Chunling
C
Fan
Qingning
Q
Su
Yun
Y
Li
Lihua
L
Liang
Daniel J
DJ
Angelini
William B
WB
Guggino
Roger A
RA
Johns
D000814:Aniline Compounds; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010766:Phosphorylation / Q000502:physiology; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D034741:RNA, Small Interfering; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D014661:Vasoconstriction / Q000502:physiology; D014966:Xanthenes
D000814:Aniline Compounds; D004963:Estrenes; C409648:Fluo 4; D005456:Fluorescent Dyes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D036341:Intercellular Signaling Peptides and Proteins; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; C413576:Retnla protein, mouse; D014966:Xanthenes; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D014443:Tyrosine; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D020962:Heterotrimeric GTP-Binding Proteins; D002118:Calcium