Characterisation of serum-induced intracellular Ca2+ oscillations in primary bone marrow stromal cells.
Intracellular Ca2+ signalling is pivotal to cell function and [Ca2+]i oscillations permit precise and prolonged modulation of an array of Ca2+-sensitive processes without the need for extended, global elevations in [Ca2+]i. We have studied [Ca2+]i signalling in primary rat marrow stromal cells exposed to foetal calf serum (FCS) constituents at concentrations up to those required to promote growth and differentiation in culture. Spontaneous [Ca2+]i signalling was not observed, but exposure to 1% FCS induced regular, sustained Ca2+ oscillations in 41 +/- 3% of cells. Incidence of FCS-induced oscillations was dose-dependent, saturating at 0.5%. These oscillations were arrested by disruption of Ca2+ stores with 100 nM-1 microM thapsigargin or discharge of mitochondrial membrane potential and were sensitive to blockade of IP3-receptors by 50 microM 2-amino-ethoxydiphenyl borate (2-APB) and inhibition of phospholipase C with 5 microM U73122. The oscillations decreased in frequency and amplitude following inhibition of Ca2+ influx with EGTA or La3+ but were poorly sensitive to nifedipine (1-10 microM) and Bay K 8644 (300 nM). The factor(s) responsible for inducing [Ca2+]i oscillations are heat stable, insensitive to disulphide bond reduction with 20 mM dithioerythritol and retained by a 30 kDa molecular weight filter. Serum is routinely present in culture medium at 10%-15% [v/v] and marrow stromal cells maintained under culture conditions exhibited sustained oscillations. This is the first demonstration of agonist-induced complex Ca2+ signals in marrow stromal cells. We conclude that Ca2+ oscillations occur constantly in these cells in culture and are potentially important regulators of cell proliferation and differentiation.
Foreman
Megan A
MA
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
Smith
Janet
J
Publicover
Stephen J
SJ
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism*; D002118:Calcium; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology*; D002417:Cattle; D005453:Fluorescence; D006358:Hot Temperature; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D044967:Serum / Q000502:physiology*; D017154:Stromal Cells / Q000378:metabolism*; D013997:Time Factors
D002121:Calcium Channel Blockers; D002118:Calcium