Objective To observe the protective effect of growth differentiation factor 11(GDF11) on myocardial injury and the changes of myocardial apoptosis in type 2 diabetic C57BL/6J mice.Methods Sixty male C57BL/6J mice weighing 20-25 g were randomly divided into three groups: control group (control), type 2 diabetes mellitus group (DM) and GDF11 intervention group (DM + GDF11).To establish mouse model of type 2 diabetes, the mice were fed with high fat and high sugar diet for 4 weeks, and i.p.injected consecutively three times of streptozotocin (STZ) in a dose of 60 mg/kg.After the continuous high-fat and high-sugar diet for 4 weeks, the cardiac function was detected by small animal ultrasound, TUNEL staining was used to detect the apoptosis in myocardium, and the expressions of cleaved-caspase-3, Bcl-2, Bax were measured.Results Diabetic injury significantly reduced the left ventricular ejection fraction and left ventricular short axis shortening rate, and increased myocardial apoptosis.Recombinant GDF11 protein significantly improved cardiac function and reduced myocardial apoptosis.Conclusions Exogenous GDF11 can significantly reduce myocardial apoptosis and improve heart function after diabetic injury.

Objective:To explore the role and mechanism of P311 in the differentiation of mouse skin fibroblasts (Fbs) into myofibroblasts.Methods:The study was an experimental research. Six 2-day-old male C57BL/6 mouse were used to extract skin Fbs by enzymatic hydrolysis method and routinely cultured. The 1 st to 3 rd passage cells were taken and divided into empty vector group transfected with empty adenovirus and P311 group transfected with P311 high expression adenovirus, and P311+myocardin-related transcription factor A (MRTF-A) small interfering RNA (siMRTF-A) group transfected with P311 high expression adenovirus and siMRTF-A according to the random number table. After 72 h of culture, the cell proliferation vitality of cells in 3 groups was detected by cell counting kit 8, the protein expressions of MRTF-A, α-smooth muscle actin (α-SMA), and serum response factor (SRF) in cells in 3 groups were detected by Western blotting, the collagen gel contraction assay was performed and the 72 h gel contraction rates in 3 groups were calculated. The sample numbers in the above experiments were all 3. The protein expressions of MRTF-A and SRF in cells, cytoplasm, and nucleus in cells in empty vector group and P311 group were detected by Western blotting, with sample number of 4. Results:After 72 h of culture, the cell proliferation vitality of cells in empty vector group, P311 group, and P311+siMRTF-A group was similar ( P>0.05). After 72 h of culture, compared with those in empty vector group, the protein expressions of MRTF-A, α-SMA, and SRF in cells in P311 group were significantly increased ( P<0.05), while the protein expressions of MRTF-A and SRF in cells in P311+siMRTF-A group were significantly decreased ( P<0.05). Compared with those in P311 group, the protein expressions of MRTF-A, SRF, and α-SMA in cells in P311+siMRTF-A group were significantly decreased ( P<0.05). The 72 h gel contraction rate showing cell contractility in P311 group was (84.8±6.2)%, which was significantly higher than (27.8±2.6)% in empty vector group and (24.7±3.2)% in P311+siMRTF-A group (with P values all <0.05). The 72 h gel contraction rates in empty vector group and P311+siMRTF-A group were similar ( P>0.05). After 72 hours of culture, the protein expressions of MRTF-A (with t values of 5.86 and 3.77, respectively, P<0.05) and SRF (with t values of 3.95 and 3.97, respectively, P<0.05) in cells and cytoplasm in P311 group were significantly higher than those in empty vector group, while the protein expressions of MRTF-A and SRF in the nucleus of cells were similar between the two groups ( P>0.05). Conclusions:P311 can promote the differentiation of fibroblasts into myofibroblasts through MRTF-A, and then participate in scar formation.