BACKGROUND:Forskolin,a diterpenoid natural compound extracted from Coleus forskohlii,has a crucial regulatory role in skeletal muscle repair.However,the regulatory role of forskolin on myogenic differentiation of C2C12 skeletal muscle cells has not been fully explored.OBJECTIVE:To explore the effects of forskolin on the differentiation of C2C12 myoblast cell line and probe into the underlying molecular mechanisms.METHODS:C2C12 cells were treated with 0,0.1,0.25,0.5,1,5,10 and 20 μmol/L forskolin during growth,and cell proliferation was detected by cell counting kit-8 and qRT-PCR.C2C12 cells were treated with 0,0.25,0.5 and 1 μmol/L forskolin during the induction of myogenic differentiation.Immunofluorescence staining and qRT-PCR were used to detect C2C12 cells differentiation.Western blot was used to detect the expression level of myogenic differentiation-related signaling pathway proteins.RESULTS AND CONCLUSION:(1)The viability of C2C12 cells was decreased and cell proliferation was inhibited after treatment with high concentrations(＞1 μmol/L)of forskolin.(2)The qRT-PCR results showed that forskolin up-regulated the expression of Myh2,Myh4,Myomaker,but down-regulated the expression of Myh7 compared with the 0 μmol/L group,when C2C12 cells were differentiated for 4 days.Immunofluorescence staining results showed that the fusion index and myotube diameter of C2C12 cells were increased after forskolin treatment,and the number of myotubes was also increased.(3)Western blot results showed that the phosphorylated extracellular signal-regulated kinase 1/2 expression was inhibited;however,the phosphorylated protein kinase B was promoted after treatment with forskolin.The protein expression level of the myogenic differentiation transcription factor Myogenin was significantly up-regulated after treatment with forskolin.The above results demonstrate that forskolin may promote myogenic differentiation of C2C12 skeletal muscle cells through the extracellular signal-regulated kinase 1/2 and protein kinase B signaling pathway.

BACKGROUND:Forskolin,a diterpenoid natural compound extracted from Coleus forskohlii,has a crucial regulatory role in skeletal muscle repair.However,the regulatory role of forskolin on myogenic differentiation of C2C12 skeletal muscle cells has not been fully explored.OBJECTIVE:To explore the effects of forskolin on the differentiation of C2C12 myoblast cell line and probe into the underlying molecular mechanisms.METHODS:C2C12 cells were treated with 0,0.1,0.25,0.5,1,5,10 and 20 μmol/L forskolin during growth,and cell proliferation was detected by cell counting kit-8 and qRT-PCR.C2C12 cells were treated with 0,0.25,0.5 and 1 μmol/L forskolin during the induction of myogenic differentiation.Immunofluorescence staining and qRT-PCR were used to detect C2C12 cells differentiation.Western blot was used to detect the expression level of myogenic differentiation-related signaling pathway proteins.RESULTS AND CONCLUSION:(1)The viability of C2C12 cells was decreased and cell proliferation was inhibited after treatment with high concentrations(＞1 μmol/L)of forskolin.(2)The qRT-PCR results showed that forskolin up-regulated the expression of Myh2,Myh4,Myomaker,but down-regulated the expression of Myh7 compared with the 0 μmol/L group,when C2C12 cells were differentiated for 4 days.Immunofluorescence staining results showed that the fusion index and myotube diameter of C2C12 cells were increased after forskolin treatment,and the number of myotubes was also increased.(3)Western blot results showed that the phosphorylated extracellular signal-regulated kinase 1/2 expression was inhibited;however,the phosphorylated protein kinase B was promoted after treatment with forskolin.The protein expression level of the myogenic differentiation transcription factor Myogenin was significantly up-regulated after treatment with forskolin.The above results demonstrate that forskolin may promote myogenic differentiation of C2C12 skeletal muscle cells through the extracellular signal-regulated kinase 1/2 and protein kinase B signaling pathway.

Objective: To analyze the expression of sigma factor in drug resistance gene mutations of Mycobacterium tuberculosis (MTB), so as to provide a reference for the drug resistance mechanism of tuberculosis. Methods: Clinical sputum specimens of outpatients at Tianjin Center for Tuberculosis from 2018 to 2022 were collected. A total of 899 MTB-positive strains were obtained by culture, and 492 phenotypically sensitive strains and 407 phenotypically resistant strains were identified by an in vitro phenotypic drug susceptibility test. Thirty drug-sensitive strains of MTB were randomly selected, and 98 drug-resistant strains with specific resistance phenotypes were chosen; all were subjected to melting curve analysis for detection of drug-resistance gene mutations. The strains were divided into sensitive strains without gene mutation, isoniazid-resistant strains with inhA mutation or katG mutation, rifampicin-resistant strains with rpoB mutation, and multigene mutation-resistant strains with inhA+rpoB mutation or katG+rpoB mutation. The mRNA relative expression of sigma factor was detected by fluorescence quantitative PCR, and the ratio of sigma factor mRNA relative expression between the experimental strain and the standard strain >2 was used to screen for highly expressed sigma factor. The differences in sigma factor mRNA relative expression and high expression rate between drug-resistant gene mutant strains and sensitive strains were analyzed. Results: Thirty sensitive strains and 90 drug-resistant strains were included. Among them, there were 16 strains with inhA mutation, 22 strains with katG mutation, 13 strains with rpoB mutation, 15 strains with inhA+rpoB mutation, and 24 strains with katG+rpoB mutation. Compared to the sigma factors of the sensitive strains, the mRNA expression levels of sigG and sigI in inhA-mutated strains, sigF, sigG, sigH, sigI, sigJ, and sigL in katG-mutated strains, and sigF, sigG, sigH, sigJ, and sigL in rpoB-mutated, inhA+rpoB-mutated, and katG+rpoB-mutated strains were significantly higher (all P<0.05). Additionally, the high-expression rates of sigI in inhA-mutated strains, sigF, sigG, sigI, sigJ, and sigL in katG-mutated and inhA+rpoB-mutated strains, and sigF, sigG, sigH, sigJ, and sigL in rpoB-mutated and katG+rpoB-mutated strains were also higher (all P<0.05). Conclusion Compared to sensitive MTB strains, sigI showed higher relative expression of mRNA and high-expression rate in inhA-mutated strains, and sigF, sigG, sigJ, and sigL had higher mRNA relative expression and high-expression rates in katG-mutated, rpoB-mutated, and multi-drug-resistant strains.

Objective To observe the clinical curative effect of unilateral biportal endoscopy(UBE)in the treatment of extreme lateral lumbar disc herniation(ELLDH).Methods From June 2019 to June 2022,25 patients with ELLDH were treated with UBE-guided discectomy,including 16 males and 9 females.The age ranged from 26 to 62 years with a mean of(53.67±17.45)years.History ranged from 3 d to 10 years.There were 9 cases of internal foraminal type(type Ⅰ),13 cases of external foraminal type(type Ⅱ)and 3 case of mixed type(type Ⅲ).There were 8 cases of L4/5 space and 17 cases of L5/S1 space.All the patients underwent anterior and lateral lumbar X-rays,CT and MRI scans before surgery.The visual analogue scale(VAS)pain score and Oswestry disability index(ODI)assessed lower limb and lower back pain and functional recovery before surgery and at 3 d and 3 months after surgery,respectively.Macnab criteria evaluated the immediate surgical outcome.Results The UBE technique was used to treat ELLDH.The operative time was(79.79±23.97)min,the intraoperative bleeding volume was 40～80 mL,with an average of(55.80±10.74)mL.Follow-up time was(7.02±4.26)months.Preoperative VAS of lower limb was(7.04±0.92),lower back VAS was(3.49±1.52),ODI was(35.03±2.97)%.Compared with the preoperative results,the lower limb VAS was(2.17±0.61),lower back VAS was(1.48±0.43),and ODI was(18.77±3.15)%on day 3 after surgery,lower limb VAS was(1.38±0.65),lower back VAS was(1.03±0.48)and ODI was(6.05±1.80)%on the 3 months after surgery were improved(P＜0.05).The excellent and good rate was 96.0%(excellent 20,good 4,fair 1),and no obvious complications were observed during the follow-up.Conclusion UBE is effective,with little trauma,clear intraoperative visual field,good intraoperative experience,and less traumatic and safe in the treatment of ELLDH.

The intracellular trafficking and subcellular distribution of exogenous gene is very important for gene delivery. A successful gene vehicle should overcome various barriers including endosomal membrane barriers to delivery gene to the target organelle. Traditional nonviral vehicle is unable to avoid endosomal pathway efficiently, so the efficiency of gene delivery is low and the application of gene drugs is limited. In order to achieve efficient nonviral gene delivery, a lot of researches based on endosomal escape have been carried out and some agents with the function of endsomal escape have been found. These agents facilitate the endsomal escape via various mechanisms, such as fusion into the lipid bilayer of endosomes, pore formation in the endosomal membrane, proton sponge effect and photochemical methods to rupture the endosomal membrane. In this review, various reported strategies for endsomal escape are described according to the escape mechanisms, and their applications in intracellular gene delivery are also discussed.