Liraglutide increases FNDC5 expression in C2C12 myotubes via activa-tion of CAMKK2/AMPK signaling pathways / 中国病理生理杂志

AIM:To investigate the effect of liraglutide ( LG) on the expression of fibronectin type Ⅲdomain-containing protein 5 (FNDC5) in the C2C12 myotubes.METHODS:The C2C12 mouse myoblast cell line was induced to differentiation.Differentiated cells were stimulated with gradient concentrations (1 ~1000 nmol/L) of LG for different time (0 ~24 h).The effects of LG on the expression of FNDC5 and the activation of adenosine 5'-monophosphate ( AMP)-activated protein kinase ( AMPK) signaling pathway were determined .After pretreated with glucagon-like peptide-1 ( GLP-1 ) receptor antagonist exendin 9-39 , the inhibitor of Ca 2+/calmodulin-dependent protein kinase kinase 2 (CAMKK2), STO609, or the inhibitor of AMPK, Compound C, the LG-induced FNDC5 expression in C2C12 myotubes was examined.The expression of FNDC5 and the activation of AMPK were determined by Western blot .RESULTS: In C2C12 myotubes, LG promoted the expression of FNDC5 in a dose-and time-dependent manner .LG also activated AMPK signaling pathway .These effects of LG were partly abolished by exendin 9-39 , STO609 and Compound C .CONCLUSION:LG promotes the expression of FNDC5 via GLP-1 receptor in the C2C12 myotubes possibly through activation of the CAMKK2/AMPK signaling pathways .

Cigarette smoke extract promotes senescence by reducing expression of HDAC2 in C2C12 myoblasts / 中国病理生理杂志

AIM:To investigate whether the cigarette smoke extract (CSE) causes senescence of C2C12 myo-blasts and the relationship between senescence and histone deacetylase 2(HDAC2).METHODS: Murine C2C12 cells were induced to differentiate into myoblasts.The HDAC2 activator and inhibitor were used to investigate the effects of CSE in the myoblasts on cell senescence and the expression of HDAC2.The expression of HDAC2 at mRNA and protein levels was determined by real-time PCR and Western blot, respectively, and the positive cell rate of β-galactosidase staining for cell senescence was also detected.RESULTS:The optimal concentration of CSE was 60 mL/L and the intervention time was 24 h.After the intervention of CSE, the positive cell rate ofβ-galactosidase staining was increased, accompanied with the reduction of HDAC2 expression at mRNA and protein levels.The expression of HDAC2 at mRNA and protein levels was increased by 4, 5, 6, 7-tetrabromobenzotriazole (TBB), accompanied with the reduction of positive cell rate ofβ-galacto-sidase staining.Furthermore, when HDAC2 expression at mRNA and protein levels was reduced by HDAC2 inhibitor valp-roic acid, the positive cell rate of β-galactosidase staining was increased.CONCLUSION: CSE promotes the senescence by reducing the expression of HDAC2 in C2C12 myoblasts.

Effect of different concentrations of calpain inhibitor ALLN on proliferation and apoptosis of C2C12 myoblasts / 中华临床营养杂志

Objective To explore the effect of different concentrations of ALLN on proliferation and apoptosis of C2C12 myoblasts.Methods After intervention with Ca2+ and ALLN,methyl thiazolyl tetrazolium and flow cytometry were used to determine the effect of Ca2+ and ALLN on the proliferation and apoptosis of C2C12 cells,respectively.The morphological changes of C2C12 myoblasts were observed using Giemsa staining.Results The absorbance of Ca2 + group was significantly lower than that of the control group (P ＜0.05).After 6,12,24,36 hours of intervention,the absorbance in ALLN groups 1 to 7 (cultured in serum-free media containing 16 mmol/L Ca2+ and ALLN at final concentrations of 3.125,6.25,12.5,25,50,100,200 μmol/L) were all significantly higher than that in the 16 mmol/L Ca2+ group (after 6 hours:0.449±0.024,0.472±0.022,0.513 ±0.008,0.540±0.014,0.588±0.016,0.607±0.030,0.700±0.020 vs.0.355 ±0.012,all P =0.000; after 12 hours:0.407 ±0.007,0.414 ±0.006,0.434 ±0.004,0.441 ±0.003,0.460 ±0.010,0.484 ± 0.006,0.525 ± 0.006 vs.0.368 ± 0.027,all P =0.000; after 24 hours:0.436±0.005,0.431 ±0.015,0.441 ±0.006,0.459 ±0.013,0.527 ±0.009,0.581 ±0.005,0.599 ±0.011 vs.0.386 ± 0.007,all P =0.000 ; after 36 hours:0.464 ± 0.022,0.460 ± 0.018,0.461 ± 0.007,0.434 ± 0.020,0.454 ± 0.028,0.479 ± 0.006,0.524 ± 0.011 vs.0.379 ± 0.011,all P =0.000),while no significant differences were observed after 48-72 hours of intervention.After treatment for 36 hours,the apoptosis rate in ALLN 10,50,100,and 200 μmol/L groups were (6.00 ± 1.20) ％,(5.02 ± 1.13) ％,(4.89±1.11)％,and (2.71 ± 1.15)％,all significantly lower than that in the Ca2+ group [(13.70 ±2.30)％] (all P =0.000).Giemsa staining showed apoptotic morphological changes in the Ca2+ group,which were obviously alleviated in the ALLN group.Conclusions Ca2+ at a concentration of 16mmol/L can induce apoptosis of C2C12 cells.In contrast,ALLN can inhibit cell apoptosis and promote proliferation in a time-and dose-dependent manner.