Characterisation of serum-induced intracellular Ca2+ oscillations in primary bone marrow stromal cells

✍ Scribed by Megan A. Foreman; Janet Smith; Stephen J. Publicover

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 401 KB
• Volume: 206
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.20521

✦ Synopsis

Abstract

Intracellular Ca^2+^ signalling is pivotal to cell function and [Ca^2+^]~i~ oscillations permit precise and prolonged modulation of an array of Ca^2+^‐sensitive processes without the need for extended, global elevations in [Ca^2+^]~i~. We have studied [Ca^2+^]~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 [Ca^2+^]~i~ signalling was not observed, but exposure to 1% FCS induced regular, sustained Ca^2+^ 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 Ca^2+^ stores with 100 nM–1 µM thapsigargin or discharge of mitochondrial membrane potential and were sensitive to blockade of IP~3~‐receptors by 50 µM 2‐amino‐ethoxydiphenyl borate (2‐APB) and inhibition of phospholipase C with 5 µM U73122. The oscillations decreased in frequency and amplitude following inhibition of Ca^2+^ influx with EGTA or La^3+^ but were poorly sensitive to nifedipine (1–10 µM) and Bay K 8644 (300 nM). The factor(s) responsible for inducing [Ca^2+^]~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 Ca^2+^ signals in marrow stromal cells. We conclude that Ca^2+^ oscillations occur constantly in these cells in culture and are potentially important regulators of cell proliferation and differentiation. J.Cell.Physiol. © 2005 Wiley‐Liss, Inc.