Objective To investigate the effects of bone morphogenetic protein-7 ( BMP7 ) on insulin signaling transduction in C2C12 myotubes and HepG2 hepatocytes, and the underlying mechanisms were studied preliminarily.Methods The C2C12 myotubes and HepG2 cells were treated with BMP7 at different concentrations.The insulin signal transduction was analyzed by Western blot.Meanwhile, total RNA was extracted and quantitative PCR was employed for detecting the effects of BMP7 on gene expressions of effectors involved in insulin signal pathway.Furthermore, JNK signal pathway was also measured.Results The protein levels of p-IR, p-Akt and p-GSK3β, as well as glucose uptake, were significantly stimulated by insulin in the C2C12 myotubes and HepG2 cells.However, these stimulations induced by insulin were largely attenuated by BMP7.The mRNA levels of Akt1, Igf1r, Insr, and Irs1 were not altered by the treatment of BMP7.The JNK signal pathway was activated by a 5-min exposure of BMP7 in the HepG2 cells, and this activation was gradually reduced along with the treating time.Conclusion BMP7 attenuates the insulin signal transduction in the HepG2 cells and C2C12 myotubes, and this attenuation effect may be through JNK activation.

Background: Fatty acid-binding protein 4 (FABP4) has been demonstrated to be a predictor of early diabetic nephropathy. However, little is known about the relationship between FABP4 and diabetic retinopathy (DR). This study explored the value of FABP4 as a biomarker of DR in patients with type 2 diabetes mellitus (T2DM). Methods: A total of 238 subjects were enrolled, including 20 healthy controls and 218 T2DM patients. Serum FABP4 levels were measured using a sandwich enzyme-linked immunosorbent assay. The grade of DR was determined using fundus fluorescence angiography. Based on the international classification of DR, all T2DM patients were classified into the following three subgroups: non-DR group, non-proliferative diabetic retinopathy (NPDR) group, and proliferative diabetic retinopathy (PDR) group. Multivariate logistic regression analyses were employed to assess the correlation between FABP4 levels and DR severity. Results: FABP4 correlated positively with DR severity (r=0.225, P=0.001). Receiver operating characteristic curve analysis was used to assess the diagnostic potential of FABP4 in identifying DR, with an area under the curve of 0.624 (37% sensitivity, 83.6% specificity) and an optimum cut-off value of 76.4 μg/L. Multivariate logistic regression model including FABP4 as a categorized binary variable using the cut-off value of 76.4 μg/L showed that the concentration of FABP4 above the cut-off value increased the risk of NPDR (odds ratio [OR], 3.231; 95% confidence interval [CI], 1.574 to 6.632; P=0.001) and PDR (OR, 3.689; 95% CI, 1.306 to 10.424; P=0.014). Conclusion FABP4 may be used as a serum biomarker for the diagnosis of DR.