Nitric oxide inhibition of Drp1-mediated mitochondrial fission is critical for myogenic differentiation

Abstract

During myogenic differentiation the short mitochondria of myoblasts change into the extensively elongated network observed in myotubes. The functional relevance and the molecular mechanisms driving the formation of this mitochondrial network are unknown. We now show that mitochondrial elongation is required for myogenesis to occur and that this event depends on the cellular generation of nitric oxide (NO). Inhibition of NO synthesis in myogenic precursor cells leads to inhibition of mitochondrial elongation and of myogenic differentiation. This is due to the enhanced activity, translocation and docking of the pro-fission GTPase dynamin-related protein-1 (Drp1) to mitochondria, leading also to a latent mitochondrial dysfunction that increased sensitivity to apoptotic stimuli. These effects of NO inhibition were not observed in myogenic precursor cells containing a dominant-negative form of Drp1. Both NO-dependent repression of Drp1 action and maintenance of mitochondrial integrity and function were mediated through the soluble guanylate cyclase. These data uncover a novel level of regulation of differentiation linking mitochondrial morphology and function to myogenic differentiation.

Inhibition of Drp1-dependent mitochondrial division impairs myogenic differentiation

“…This study (13) elegantly demonstrated that, using a specific nitric oxide (NO) synthase inhibitor, inhibition of NO/cGMP pathway increased Drp1 GTPase activity, translocation, and binding to mitochondria, which was accompanied by downregulation of the key myogenic regulatory factors. These results suggest that NO-dependent inhibition of Drp1 is an important step during early myogenic differentiation, which is seemingly contradictory to our finding that inhibition of Drp1 activity impairs myogenic differentiation.…”

“…Interestingly, a recent study by De Palma et al (13) reported that enhanced Drp1 activity and the resultant excessive mitochondrial fragmentation delayed myogenic differentiation, especially in the early phase of differentiation (3-12 h in DM). This study (13) elegantly demonstrated that, using a specific nitric oxide (NO) synthase inhibitor, inhibition of NO/cGMP pathway increased Drp1 GTPase activity, translocation, and binding to mitochondria, which was accompanied by downregulation of the key myogenic regulatory factors.…”

Amphiphysin (BIN1) negatively regulates dynamin 2 for normal muscle maturation

“…Primary cell culture and differentiation Primary myoblasts from WT newborn mice were prepared using a protocol adapted from De Palma et al (44). After hind limb muscle isolation, muscles were minced and digested for 1.5 hours in PBS containing 0.5 mg/ml collagenase (Sigma-Aldrich) and 3.5 mg/ml Dispase (Gibco).…”

Skeletal muscle insulin resistance: role of mitochondria and other ROS sources

“…Indeed, it increases mitochondrial fragmentation and cell death in neurodegenerative diseases by its effects on dynaminrelated protein-1 (DRP1), which promotes mitochondrial fission (Cho et al 2009). Conversely, in myogenesis, NO • promotes the fusion of mitochondria into an elongated network by inhibiting Drp1-mediated fission (De Palma et al 2010).…”