Sphingosine 1-phosphate induces cytoskeletal reorganization in C2C12 myoblasts: physiological relevance for stress fibres in the modulation of ion current through stretch-activated channels

Abstract

Sphingosine 1-phosphate (S1P) is a bioactive lipid that is abundantly present in the serum and mediates multiple biological responses. With the aim of extending our knowledge on the role played by S1P in the regulation of cytoskeletal reorganization, native as well as C2C12 myoblasts stably transfected with green fluorescent protein (GFP)-tagged α- and β-actin constructs were stimulated with S1P (1 μM) and observed under confocal and multiphoton microscopes. The addition of S1P induced the appearance of actin stress fibres and focal adhesions through Rho- and phospholipase D (PLD)-mediated pathways. The cytoskeletal response was dependent on the extracellular action of S1P through its specific surface receptors, since the intracellular delivery of the sphingolipid by microinjection was unable to modify the actin cytoskeletal assembly. Interestingly, it was revealed by whole-cell patch-clamp that S1P-induced stress fibre formation was associated with increased ion currents and conductance through stretch-activated channels (SACs), thereby suggesting a possible regulatory role for organized actin in channel sensitivity. Experiments aimed at stretching the plasma membrane of C2C12 cells, using the cantilever of an atomic force microscope, indicated that there was a Ca2+ influx through putative SACs. In conclusion, the present data suggest novel mechanisms of S1P signalling involving actin cytoskeletal reorganization and Ca2+ elevation through SACs that might influence myoblastic functions.

Neuronal differentiation of human mesenchymal stem cells: Changes in the expression of the Alzheimer's disease-related gene seladin-1

“…Electrode capacitance was compensated before disrupting the patch. All the passive properties parameters were estimated as in Formigli et al [25]. All experiments were performed at room temperature (20-23°C).…”

Functional interaction between TRPC1 channel and connexin-43 protein: a novel pathway underlying S1P action on skeletal myogenesis

“…mobilization [6,8,9], actin cytoskeletal remodeling, and mechanosensitive stretch-activated cation channel (SAC) opening [10,11]. The formation of stress fibers by S1P has been associated with plasma membrane stretching and, in turn, with SAC activation in C2C12 myoblasts [12,13]. Several members of the transient receptor potential canonical (TRPC) ion channel family are recognized as promising candidates for SACs in different cell types [14], including sensory neurons [15], vascular smooth muscle [16], endothelial cells [17], and skeletal myoblasts [4].…”

An historical perspective on cell mechanics

“…Although the measurement of accurate mechanical parameters is of extreme importance, the idea of controlling and altering biological pathways is equally enticing. Previously, it has been shown that mechanical force delivered by the AFM tip can induce various chemo-mechanical responses [167][168][169]. In recent work, it has also been shown that the mechanical environment of many cell types (including cancer and stem cells) can be used to control and alter gene expression and differentiation pathways [21-25, 164,170,171].…”