Follistatin treatment suppresses SERCA1b levels independently of other players of calcium homeostasis in C2C12 myotubes

Abstract

Follistatin (FS) is a high affinity activin-binding protein, neutralizing the effects of the Transforming Growth Factor-beta (TGF-β) superfamily members, as myostatin (MSTN). Since MSTN emerged as a negative regulator, FS has been considered as a stimulator of skeletal muscle growth and differentiation. Here, we studied the effect of FS administration on the Ca-homeostasis of differentiating C2C12 skeletal muscle cells. FS-treatment increased the fusion index, the size of terminally differentiated myotubes, and transiently elevated the expression of the calcium-dependent protein phosphatase, calcineurin, at the beginning of differentiation. Functional experiments did not detect any alterations in the Ca transients following the stimulation by KCl or caffeine in myotubes. On the other hand, decreased Ca-uptake capability was determined by calculating the maximal pump rate (332 ± 17 vs. 279 ± 11 µM/s, in control and FS-treated myotubes, respectively; p < 0.05). In the same way, the expression and ATPase activity of the neonatal sarcoplasmic/endoplasmic reticulum CaATPase (SERCA1b) were decreased (0.59 ± 0.01 vs. 0.19 ± 0.01 mM ATP/min, in control and FS-treated myotubes, respectively; p < 0.05). However, the expression level of other proteins involved in Ca-homeostasis and differentiation (calsequestrin, STIM1, MyoD) were not affected. Our results suggest that the FS controlled myotube growth is paralleled with the tight regulation of cytosolic calcium concentration, and the decline of SERCA1b appears to be one of the key components in this process.

Stem cells from human apical papilla decrease neuro-inflammation and stimulate oligodendrocyte progenitor differentiation via activin-A secretion

“…As the percentage of GalC + area was higher in the tri-cultures than in cultures supplemented with exogenous activin-A, and as this percentage was reduced nonetheless at the same level by follistatin than in exogenous activin-A supplemented cultures, we concluded that activin-A was required but did not induce OPC differentiation alone. Supporting this hypothesis is the fact that as follistatin is mostly known to inhibit activin-A, it also inhibits factors from the TGF superfamily such as the bone morphogenic proteins [56]. It may be hypothesized that SCAP produce other essential bioactive molecules that stimulate OPC differentiation along with activin-A, the actions of which are also inhibited by follistatin.…”

The Meeting of Micropeptides with Major Ca2+ Pumps in Inner Membranes—Consideration of a New Player, SERCA1b

“…Additionally, in wild-type C2C12 cells, the growth stimulator follistatin, an antagonist of the muscle growth inhibitor myostatin, selectively suppressed Ca 2+ uptake and SERCA1b expression. This indicates that SERCA1b is tightly coupled with stages of ongoing differentiation [ 101 ]. The expression pattern of MLN, the first discovered regulin [ 62 ] mirrors that of SERCA1b [ 94 ].…”

Automatic Quantitative Segmentation of Myotubes Reveals Single-cell Dynamics of S6 Kinase Activation

“…C2C12 cells, derived from mice myoblasts, have been used as model cell lines for the study of cell differentiation and muscle functions in vitro (Fodor et al, 2017;Rahar et al, 2018;Rapizzi et al, 2008;Soltow et al, 2013). By differentiation induction of C2C12 cells, a large subpopulation of myoblasts forms elongated polynuclear myotubes, while a subpopulation of the cells, called reserve cells, remains undifferentiated ( Fig.…”