Ubiquitin C-Terminal Hydrolase L1 regulates myoblast proliferation and differentiation

Abstract

Skeletal muscles are dynamic tissues that possess regenerative abilities, which require multiple processes and regulatory factors. Ubiquitin C-Terminal Hydrolase L1 (UCHL1), which is primarily expressed in neuronal tissues, was upregulated in skeletal muscles in disease conditions but its functional role in skeletal muscles is unknown. Using mouse myoblast cells C2C12 as an in vitro model, this study reported that UCHL1 elicits different regulation in myoblast cell proliferation and differentiation. We first observed that UCHL1 protein level was continuously declined during cell differentiation. Gene knockdown of UCHL1 by siRNA resulted in a significant decrease in cell proliferation but marked acceleration of cell differentiation and myotube formation. Meanwhile, UCHL1 gene knockdown upregulated myogenic factors myoD and Myogenin (MyoG). In mice, UCHL1 was significantly upregulated in denervated skeletal muscle. Overall, these novel data suggest that UCHL1 may play a role in myogenesis by promoting myoblast proliferation and inhibiting differentiation.

UCHL1 regulates oxidative activity in skeletal muscle

“…Originally discovered as a neuronal protein, UCHL1 has not been recognized to also express in skeletal muscle until recently [ 13 , 14 ], and its functional roles in the muscle remain unclear. We recently reported that UCHL1 has an inhibitory effect on myoblast C2C12 differentiation [ 15 ]. The results of the present study reveal for the first time that UCHL1 is present in oxidative skeletal muscles and is essential for muscle oxidative activity.…”

“…Western blot was performed as described previously [ 20 , 23 , 24 ]. Briefly, samples of 15–30 μg of total proteins were subject to electrophoresis in 9–15% gradient gels at 100 V for 2 hours.…”

“…As previously described [ 15 ], C2C12 myoblasts were cultured in growing medium (GM) which was Dulbecco’s Modified Eagle’s Medium (DMEM, ATCC) supplemented with 10% fetal bovine serum (FBS, GE HyClone, Logan, UT) and 1% penicillin-streptomycin. Growing to 80–90% confluence, cells were infected with adenovirus expressing mouse UCHL1 tagged with HA (Ad.UCHL1-HA) in differentiating medium (DM) that was DMEM supplemented with 2% horse serum (GE HyClone) and 1% penicillin-streptomycin.…”

“…It was recently reported that UCHL1 was expressed in mouse skeletal muscle in disease conditions [ 13 , 14 ]. We recently showed that UCHL1 was expressed in C2C12 mouse myoblast cells and was involved in the regulation of cell proliferation and differentiation [ 15 ]. To study the function of UCHL1 in skeletal muscle, we have recently developed a mouse model with skeletal muscle specific knockout (smKO) of UCHL1.…”

The deubiquitinating enzyme UCHL1 is a favorable prognostic marker in neuroblastoma as it promotes neuronal differentiation

“…Recent studies have found that UCHL1 plays important roles in cell differentiation. For example, Gao H et al demonstrated that UCHL1 played a role in myogenesis by inhibiting differentiation [ 36 ], while Sakura et al found that UCHL1 could regulate the morphology of neural progenitor cells and modulate their differentiation thereby enhancing neurogenesis in the embryonic brain [ 25 ]. In this study, we found that UCHL1 expression was significantly higher in GNB/GN and well-differentiated NB than poorly differentiated NB, and UCHL1 expression was positively correlated with the known neural differentiation markers.…”