title: Ca2+ handling is altered when arterial myocytes progress from a contractile to a proliferative phenotype in culture.
abstract: Phenotypic modulation of vascular myocytes is important for vascular development and adaptation. A characteristic feature of this process is alteration in intracellular Ca(2+) handling, which is not completely understood. We studied mechanisms involved in functional changes of inositol 1,4,5-trisphosphate (IP(3))- and ryanodine (Ry)-sensitive Ca(2+) stores, store-operated Ca(2+) entry (SOCE), and receptor-operated Ca(2+) entry (ROCE) associated with arterial myocyte modulation from a contractile to a proliferative phenotype in culture. Proliferating, cultured myocytes from rat mesenteric artery have elevated resting cytosolic Ca(2+) levels and increased IP(3)-sensitive Ca(2+) store content. ATP- and cyclopiazonic acid [CPA; a sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) inhibitor]-induced Ca(2+) transients in Ca(2+)-free medium are significantly larger in proliferating arterial smooth muscle cells (ASMCs) than in freshly dissociated myocytes, whereas caffeine (Caf)-induced Ca(2+) release is much smaller. Moreover, the Caf/Ry-sensitive store gradually loses sensitivity to Caf activation during cell culture. These changes can be explained by increased expression of all three IP(3) receptors and a switch from Ry receptor type II to type III expression during proliferation. SOCE, activated by depletion of the IP(3)/CPA-sensitive store, is greatly increased in proliferating ASMCs. Augmented SOCE and ROCE (activated by the diacylglycerol analog 1-oleoyl-2-acetyl-sn-glycerol) in proliferating myocytes can be attributed to upregulated expression of, respectively, transient receptor potential proteins TRPC1/4/5 and TRPC3/6. Moreover, stromal interacting molecule 1 (STIM1) and Orai proteins are upregulated in proliferating cells. Increased expression of IP(3) receptors, SERCA2b, TRPCs, Orai(s), and STIM1 in proliferating ASMCs suggests that these proteins play a critical role in an altered Ca(2+) handling that occurs during vascular growth and remodeling.
authors.affiliation: Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Roberto
authors.initials: R
authors.lastname: Berra-Romani
authors.forename: Amparo
authors.initials: A
authors.lastname: Mazzocco-Spezzia
authors.forename: Maria V
authors.initials: MV
authors.lastname: Pulina
authors.forename: Vera A
authors.initials: VA
authors.lastname: Golovina
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002110:Caffeine / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D049109:Cell Proliferation; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D007211:Indoles / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D017538:Mesenteric Artery, Superior / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010641:Phenotype; D051381:Rats; D017207:Rats, Sprague-Dawley; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation; D014661:Vasoconstriction
chemical_list: C506948:Atp2a2 protein, rat; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D007211:Indoles; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008562:Membrane Glycoproteins; D019837:Ryanodine Receptor Calcium Release Channel; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels; D012433:Ryanodine; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D016257:Fura-2; C000543:cyclopiazonic acid