1,4,5-Inositol trisphosphate-operated intracellular Ca(2+) stores and angiotensin-II/endothelin-1 signaling pathway are functional in human embryonic stem cell-derived cardiomyocytes.
On the basis of previous findings suggesting that in human embryonic stem cell-derived cardiomyocytes (hESC-CM) the sarcoplasmic reticulum Ca(2+)-induced release of calcium machinery is either absent or immature, in the present study we tested the hypothesis that hESC-CM contain fully functional 1,4,5-inositol trisphosphate (1,4,5-IP(3))-operated intracellular Ca(2+) ([Ca(2+)](i)) stores that can be mobilized upon appropriate physiological stimuli. To test this hypothesis we investigated the effects of angiotensin-II (AT-II) and endothelin-1 (ET-1), which activate the 1,4,5-IP(3) pathway, on [Ca(2+)](i) transients and contractions in beating clusters of hESC-CM. Our major findings were that in paced hESC-CM both AT-II and ET-1 (10(-9) to 10(-7) M) increased the contraction amplitude and the maximal rates of contraction and relaxation. In addition, AT-II (10(-9) to 10(-7) M) increased the [Ca(2+)](i) transient amplitude. The involvement of 1,4,5-IP(3)-dependent intracellular Ca(2+) release in the inotropic effect of AT-II was supported by the findings that (a) hESC-CM express AT-II, ET-1, and 1,4,5-IP(3) receptors determined by immunofluorescence staining, and (b) the effects of AT-II were blocked by 2 microM 2-aminoethoxyphenyl borate (a 1,4,5-IP(3) receptor blocker) and U73122 (a phospholipase C blocker). In conclusion, these findings demonstrate for the first time that hESC-CM exhibit functional AT-II and ET-1 signaling pathways, as well as 1,4,5-IP(3)-operated releasable Ca(2+) stores.
Sedan
Oshra
O
Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Dolnikov
Katya
K
Zeevi-Levin
Naama
N
Leibovich
Noa
N
Amit
Michal
M
Itskovitz-Eldor
Joseph
J
Binah
Ofer
O
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology*; D019332:Endothelin-1 / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D015398:Signal Transduction
D019332:Endothelin-1; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D011943:Receptors, Adrenergic, beta; D000804:Angiotensin II; D002118:Calcium