title: TRPC1, STIM1, and ORAI influence signal-regulated intracellular and endoplasmic reticulum calcium dynamics in human myometrial cells.
abstract: To explore the relationship between signal-stimulated increases in intracellular calcium ([Ca(2+)](i)) and depletion and refilling of the endoplasmic reticulum (ER) Ca(2+) stores ([Ca(2+)](L)) in human myometrial cells, we measured simultaneous changes in [Ca(2+)](i) and [Ca(2+)](L) using Fura-2 and Mag-fluo-4, respectively, in PHM1-41 immortalized and primary cells derived from pregnant myometrium and in primary cells derived from nonpregnant tissue. Signal- and extracellular Ca(2+)-dependent increases in [Ca(2+)](i) (SRCE) and ER refilling stimulated by oxytocin and cyclopiazonic acid were not inhibited by voltage-operated channel blocker nifedipine or mibefradil, inhibition of Na(+)/Ca(2+) exchange with KB-R7943, or zero extracellular Na(+) in PHM1-41 cells. Gadolinium-inhibited oxytocin- and cyclopiazonic acid-induced SRCE and slowed ER store refilling. TRPC1 mRNA knockdown specifically inhibited oxytocin-stimulated SRCE but had no statistically significant effect on ER store refilling and no effect on either parameter following cyclopiazonic acid treatment. Dominant negative STIMΔERM expression attenuated oxytocin- and thapsigargin-stimulated SRCE. Both STIM1 and ORAI1-ORAI3 mRNA knockdowns significantly attenuated oxytocin- and cyclopiazonic acid-stimulated SRCE. The data also suggest that reduction in STIM1 or ORAI1-ORAI3 mRNA can impede the rate of ER store refilling following removal of SERCA inhibition. These data provide evidence for both distinct and overlapping influences of TRPC1, STIM1, and ORAI1-ORAI3 on SRCE and ER store refilling in human myometrial cells that may contribute to the regulation of myometrial Ca(2+) dynamics. These findings have important implications for understanding the control of myometrial Ca(2+) dynamics in relation to myometrial contractile function.
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.
authors.forename: Dilyara A
authors.initials: DA
authors.lastname: Murtazina
authors.forename: Daesuk
authors.initials: D
authors.lastname: Chung
authors.forename: Aida
authors.initials: A
authors.lastname: Ulloa
authors.forename: Emily
authors.initials: E
authors.lastname: Bryan
authors.forename: Henry L
authors.initials: HL
authors.lastname: Galan
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Sanborn
mesh_terms: D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D009215:Myometrium / Q000166:cytology*; D011247:Pregnancy; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D015220:Calcium Channels; D043562:Receptors, G-Protein-Coupled; D002118:Calcium