Effects of S1P on myoblastic cell contraction: Possible involvement of Ca2+-independent mechanisms

Nosi, D., Vassalli, M. , Polidori, L., Giannini, R., Tani, A., Chellini, F. and Paternostro, F. (2004) Effects of S1P on myoblastic cell contraction: Possible involvement of Ca2+-independent mechanisms. Cells Tissues Organs, 178(3), pp. 129-138. (doi: 10.1159/000082243) (PMID:15655330)

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Abstract

Sphingosine-1-phosphate (S1P) is a lipid mediator, which affects many essential processes such as cell proliferation, differentiation and contraction in many cell types. We have previously demonstrated that the lipid mediator elicits Ca2+ transients in a myoblastic cell line (C2C12) by interacting with its specific receptors (S1PRs). In the present study, we wanted to correlate the Ca2+ response with activation of myoblastic cell contractility. C2C12 cells were first investigated for the expression and cellular organization of cytoskeletal proteins by immunoconfocal microscopy. We found that myoblasts exhibited a quite immature cytoskeleton, with filamentous actin dispersed as a web-like structure within the cytoplasm. To evaluate intracellular Ca2+ mobilization, the cells were loaded with a fluorescent Ca2+ indicator (Fluo-3), stimulated with S1P and simultaneously observed with differential interference contrast and fluorescence optics. Exogenous S1P-induced myoblastic cell contraction was temporally unrelated to S1P-induced intracellular Ca2+ increase; cell contraction occurred within 5–8 s from stimulation, whereas intracellular Ca2+ increase was evident only after 15–25 s. To support the Ca2+ independence of myoblastic cell contraction, the cells were pretreated with a Ca2+ chelator, BAPTA/AM, prior to stimulation with S1P. In these experimental conditions, the myoblasts were still able to contract, whereas the S1P-induced Ca2+ transients were completely abolished. On the contrary, when C2C12 cells were induced to differentiate into skeletal myotubes, they responded to S1P with a rapid cell contraction concurrent with an increase in the intracellular Ca2+. These data suggest that Ca2+-independent mechanism of cell contraction may be replaced by Ca2+-dependent ones during skeletal muscle differentiation.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Vassalli, Dr Massimo
Authors: Nosi, D., Vassalli, M., Polidori, L., Giannini, R., Tani, A., Chellini, F., and Paternostro, F.
College/School:College of Science and Engineering > School of Engineering > Biomedical Engineering
Journal Name:Cells Tissues Organs
Publisher:Karger
ISSN:1422-6405
ISSN (Online):1422-6421

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