Hepatocyte Growth Factor Regulates the miR-206-HDAC4 Cascade to Control Neurogenic Muscle Atrophy following Surgical Denervation in Mice

Wooshik Choi,Junghun Lee,Jaeman Lee,Kyeong Ryang Ko,Sunyoung Kim

doi:10.1016/j.omtn.2018.06.013

Abstract

Hepatocyte growth factor (HGF) has been well characterized for its roles in the migration of muscle progenitors during embryogenesis and the differentiation of muscle stem cells, but its function in adult neurogenic muscle atrophic conditions is poorly understood. Here we investigated whether HGF/c-met signaling has any effects on muscle-atrophic conditions. It was found that HGF expression was upregulated in skeletal muscle tissue following surgical denervation and in hSOD1-G93A transgenic mice showing severe muscle loss. Pharmacological inhibition of the c-met receptor decreased the expression level of pri-miR-206, enhanced that of HDAC4 and atrogenes, and resulted in increased muscle atrophy. In C2C12 cells, HGF inhibited phosphorylation of Smad3 and relieved TGF-β-mediated suppression of miR-206 expression via JNK. When extra HGF was exogenously provided through intramuscular injection of plasmid DNA expressing HGF, the extent of muscle atrophy was reduced, and the levels of all affected biochemical markers were changed accordingly, including those of primary and mature miR-206, HDAC4, and various atrogenes. Taken together, our finding suggested that HGF might play an important role in regard to neurogenic muscle atrophy and that HGF might be used as a platform to develop therapeutic agents for neuromuscular disorders.

Highlights

Skeletal muscle is a highly dynamic tissue that can vary in size, structure, and contractile force under different conditions
Hepatocyte growth factor (HGF)/c-met Signaling Was Upregulated in Denervated Muscle To investigate the possible involvement of HGF in neurogenic muscle atrophy, a sciatic nerve transection model, in which irreversible damage was made to the nerve by cutting the sciatic nerve, was used
Denervation was induced by severing the sciatic nerve of a 10-weekold C57BL/6 mouse, and total proteins were prepared from the tibialis anterior (TA) muscle of the injury site at appropriate time points, followed by ELISA

Summary

INTRODUCTION

Skeletal muscle is a highly dynamic tissue that can vary in size, structure, and contractile force under different conditions. One of the pathological hallmarks of motor neuron diseases, such as amyotrophic lateral sclerosis (ALS) or poliomyelitis, is deterioration of muscle innervation In these diseases, the skeletal muscle undergoes severe physiological changes, such as debilitating muscle loss because of the deficiency in neural input. MiR-206, a member of muscle-enriched miRNAs (myo-miR), is known to facilitate muscle differentiation by regulating the expression of myogenic regulatory factors in vitro[4,5] and in vivo.[6] It was recently shown that miR-206 could delay the progression of ALS by suppressing the expression of HDAC4 and, thereby, promoting regeneration of the neuromuscular synapse, suggesting that miR-206 might affect the course of the neurogenic muscle-atrophic condition.[7]. Our data suggest that HGF might be used as a platform for developing therapeutic agents to treat neurogenic muscle atrophy

RESULTS

DISCUSSION

MATERIALS AND METHODS