[P2-1~135] Poster Presentation 2

[P2-46] The role of microRNA133 decreased expression in impaired insulin signaling in skeletal muscle of catch-up growth IUGR rats

^○Lihong Liao^{1, 2} (1.Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan, China, 2.Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China)

[Objective] To investigate the role of microRNA-133 in disorders of glucose transport in catch-up growth intrauterine growth restriction (CG-IUGR) rats. [Methods] microRNA-133a-sponge adenovirus and microRNA-133b-sponge adenovirus were used to transfect rat skeletal muscle myoblast L6 cell lines to hamper microRNA-133 function. The expressions of microRNA-133a, microRNA-133b, Akt2, KLF15, PGC-1α, GLUT4, and MEF2a were examined using RT-PCR. The CG-IUGR rat model was established by restricting diet during pregnancy, limiting the lactation number and extending the lactation time after birth. The expressions of microRNA-133a and microRNA-133b by were detected via RT-PCR in thigh skeletal muscle tissue in 4-week-old IUGR rats. The mRNA and protein expression of Akt2, KLF15, PGC-1α, GLUT4 and MEF2a was explored using RT-PCR and Western Blotting. [Results] In microRNA-133-sponge adenovirus transfected L6 cells group, KLF15 and GLUT4 protein levels were significantly higher than those in the vector group (p < 0.05). microRNA-133 expressions in CG-IUGR rat skeletal muscle reduced significantly, and KLF15, AKT2, PGC-1α mRNA and protein levels associated with energy metabolism and insulin pathway signal decreased significantly in the skeletal muscle of CG-IUGR rats. [Conclusions] microRNA-133 could negative-regulate translation of its target gene mRNA in vitro. Our results are the first to report alterations in expression of microRNA-133 in skeletal muscle of CG-IUGR. Interestingly, in vivo, microRNA-133 expression decreased, and there was a downward trend of target gene expression and protein levels. We presume that the decreased expression level of microRNA-133 in CG-IUGR rats is neither the cause nor stimuli of impaired insulin signal pathway; by contrast, it may soften the unfavorable effect of adverse intrauterine environment instead.
Key words microRNA-133; intrauterine growth restriction; catch-up growth; insulin resistance