Inhibition of Glycogen Synthase Kinase-3β Attenuates Glucocorticoid-Induced Suppression of Myogenic Differentiation In Vitro

Abstract

Glucocorticoids are the only therapy that has been demonstrated to alter the progress of Duchenne muscular dystrophy (DMD), the most common muscular dystrophy in children. However, glucocorticoids disturb skeletal muscle metabolism and hamper myogenesis and muscle regeneration. The mechanisms involved in the glucocorticoid-mediated suppression of myogenic differentiation are not fully understood. Glycogen synthase kinase-3β (GSK-3β) is considered to play a central role as a negative regulator in myogenic differentiation. Here, we showed that glucocorticoid treatment during the first 48 h in differentiation medium decreased the level of phosphorylated Ser9-GSK-3β, an inactive form of GSK-3β, suggesting that glucocorticoids affect GSK-3β activity. We then investigated whether GSK-3β inhibition could regulate glucocorticoid-mediated suppression of myogenic differentiation in vitro. Two methods were employed to inhibit GSK-3β: pharmacological inhibition with LiCl and GSK-3β gene knockdown. We found that both methods resulted in enhanced myotube formation and increased levels of muscle regulatory factors and muscle-specific protein expression. Importantly, GSK-3β inhibition attenuated glucocorticoid-induced suppression of myogenic differentiation. Collectively, these data suggest the involvement of GSK-3β in the glucocorticoid-mediated impairment of myogenic differentiation. Therefore, the inhibition of GSK-3β may be a strategy for preventing glucocorticoid-induced muscle degeneration.

Glucocorticoids Improve Myogenic Differentiation In Vitro by Suppressing the Synthesis of Versican, a Transitional Matrix Protein Overexpressed in Dystrophic Skeletal Muscles

“…Our observation of a concentration dependent increase in myoblast fusion and myotube formation following low dose, 25 nM and 100 nM, dexamethasone treatment is in concordance with a number of studies reporting positive effects of glucocorticoids on myogenesis in vitro [ 39 , 40 ] and muscle regeneration in vivo [ 12 , 37 ]. In contrast to our findings, Ma et al [ 79 ] reported inhibition of myogenic differentiation of C2C12 and primary mouse myoblasts following glucocorticoid treatment through the activation of glycogen synthase kinase 3β (GSK-3β). However, the concentration of dexamethasone used (10 μM) was 100–400 folds higher than our low dose treatment [ 79 ].…”

“…In contrast to our findings, Ma et al [ 79 ] reported inhibition of myogenic differentiation of C2C12 and primary mouse myoblasts following glucocorticoid treatment through the activation of glycogen synthase kinase 3β (GSK-3β). However, the concentration of dexamethasone used (10 μM) was 100–400 folds higher than our low dose treatment [ 79 ]. Furthermore, with lower concentrations of 10 nM and 100 nM dexamethasone, no significant decrease in myogenin or myosin heavy chain protein expression was reported, whilst the fusion index was not assessed [ 79 ].…”

“…However, the concentration of dexamethasone used (10 μM) was 100–400 folds higher than our low dose treatment [ 79 ]. Furthermore, with lower concentrations of 10 nM and 100 nM dexamethasone, no significant decrease in myogenin or myosin heavy chain protein expression was reported, whilst the fusion index was not assessed [ 79 ].…”

Angiotensin-II-induced Muscle Wasting is Mediated by 25-Hydroxycholesterol via GSK3β Signaling Pathway

“…Pharmacological inhibition of GSK3β attenuates TNF-α and glucocorticoid induced suppression of MyoD expression and myotube formation in C2C12 and primary satellite cells (Ma et al, 2014, Verhees et al, 2013). TDZD-8 also improved muscle strength and Pax7 expression (a marker for satellite cells) in HSA LR mice, a mouse model of myotonic dystrophy (Jones et al, 2012).…”

Glycogen synthase kinase 3β (GSK3β) regulates the expression of MyHC2a in goat skeletal muscle satellite cells (SMSCs)

“…Treatment of IGF‐1 or GSK3β inhibitor in differentiated C2C12 cells accelerates myogenesis shown in increased myotube formation, muscle creatine kinase (MCK) activity, and transactivation of troponin I (TnI) promoter, as well as increases the expression of MyoD, Myf5, myogenin, TnI‐slow, TnI‐fast, MCK, and myoglobin (Jl et al, ). In addition, GSK3β inhibition increases the expression of muscle regulatory protein, enhances myotube formation, and attenuates glucocorticoid‐induced suppression of myogenic differentiation (Ma, Zhong, Zheng, Shi, & Zhang, ). Here we showed that GSK3β inhibition promoted the differentiation of goat SMSCs and increased the expressions of MyoG, MyoD, MyHC1, and MyHC2a genes (Figure c‐f), suggesting that GSK3β may play important roles in goat skeletal muscle development.…”