The chemokine SDF1 controls multiple steps of myogenesis through atypical PKCζ

Abstract

Mice deficient in the SDF1-chemokine-receptor CXCR4, exhibit severe defects of secondary limb myogenesis. To further elucidate the role of SDF1 in muscle development, we have now analyzed putative effects of this chemokine on proliferation, migration and myogenic differentiation of mouse C2C12 myogenic progenitor/myoblast cells. In addition, we have characterized the signaling pathways employed by SDF1-CXCR4 to control myogenesis. We found that SDF1 stimulates proliferation and induces migration of C2C12 cells with a potency similar to that of FGF2 and HGF, which both represent prototypical extracellular regulators of myogenesis. In addition, SDF1 inhibits myogenic differentiation in both C2C12 cells and primary myoblasts, as assessed by MyoD, myosin heavy chain and/or myogenin expression. Regarding signaling pathways, C2C12 cells responded to SDF1 with activation (phosphorylation) of Erk and PKCζ, whereas even after prolonged SDF1 treatment for up to 120 minutes, levels of activated Akt, p38 and PKCα or PKCβ remained unaffected. Preventing activation of the classic MAP kinase cascade with the Erk inhibitor UO126 abolished SDF1-induced proliferation and migration of C2C12 cells but not the inhibitory action of SDF1 on myogenic differentiation. Moreover, the effects of SDF1 on proliferation, migration and differentiation of C2C12 cells were all abrogated in the presence of myristoylated PKCζ peptide pseudosubstrate and/or upon cellular depletion of PKCζ by RNA interference. In conclusion, our findings unravel a previously unknown role of CXCR4-PKCζ signaling in myogenesis. The potent inhibitory effects of SDF1 on myogenic differentiation point to a major function of CXCR4-PKCζ signaling in the control of secondary muscle growth.

SDF-1 controls the muscle and blood vessel formation of the somite

“…On the second reincubation day, SDF-1 did not influence the cell proliferation. Such a short term effect of SDF-1 was also reported by other studies (Odemis et al, 2007;Melchionna et al, 2010). After treating C2C12 cells with SDF-1 (10 ng/ml, low concentration) for 24 hours, the number of Ki67-positive (proliferation marker) cells was increased.…”

“…After treating C2C12 cells with SDF-1 (10 ng/ml, low concentration) for 24 hours, the number of Ki67-positive (proliferation marker) cells was increased. However, after 48 hours, the number of Ki67-positive cells returned to the same level as under control conditions (Odemis et al, 2007). Treatment of C2C12 myoblasts and mouse satellite cells with SDF-1 (100 ng/ml, high concentration) for 24 hours led to a stimulation of myotube formation.…”

Myoblast fusion: lessons from flies and mice

“…Time-lapse analyses in vitro indicate that freshly isolated satellite cells migrate extensively on their associated myofibers, consistent with their expression of receptors for chemoregulatory molecules (Siegel et al, 2009). Furthermore, myoblasts cultured on various artificial substrates are also motile and migrate in response to a variety of factors, including chemokines (Corti et al, 2001;Odemis et al, 2007;Griffin et al, 2010), growth factors (Robertson et al, 1993a;Bischoff, 1997;Lee et al, 1999;Corti et al, 2001;Villena and Brandan, 2004) and other molecules (Nedachi et al, 2009;Tokura et al, 2011). Except for Cxcr4 [chemokine (C-X-C motif) receptor 4], the receptor for the chemokine Sdf1 (stromal-derived factor 1; Cxcl12 -Mouse Genome Informatics) (Griffin et al, 2010), the effect of depleting these molecules on cell fusion has not been tested.…”

CXCR7 is an active component of SDF-1 signalling in astrocytes and Schwann cells

“…To analyze SDF-1-induced signalling in the different glial cell types, we focused on p38, extracellular-signal-regulated kinases 1 and 2 (Erk1/2), Akt, the conventional protein kinase C (PKC) isoforms  and  (PKC/), and the atypical PKC isoforms  and  (PKC/) -signalling molecules and pathways that are activated by SDF-1 (Wang et al, 2000;Bajetto et al, 2001;Ödemis et al, 2007;Li and Ransohoff, 2008). Stimulation of cultured astrocytes with SDF-1 (1-100 ng/ml; 10 minutes) resulted in the dose-dependent activation (phosphorylation) of Erk1/2, Akt and PKC/, but not p38 and PKC/ (Fig.…”