Modulation of adiponectin receptor AdipoR1 and miR-221 in skeletal muscle of trained and high-fat diet fed C57BL/6 mice

• Grant number: 16/08865-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2016
• End date: July 31, 2017
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Helena Cristina de Lima Barbosa
• Grantee: Mariana Cagnin
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 13/07607-8 - OCRC - Obesity and Comorbidities Research Center, AP.CEPID

Abstract

Insulin resistance is characterized by decreased insulin sensitivity, or the ability of adipose cells, muscle tissue and the liver be sensitized by insulin when glucose in blood is high. Increased adiponectin receptor AdipoR1 expression leads to the improvement of insulin resistance and type 2 diabetes. There is evidence that AdipoR1 can be regulated by miR-221, which is increased during insulin resistance and obesity therefore, reducing the expression of AdipoR1. Then, considering the beneficial effect of exercise on insulin sensitivity, our hypothesis is that the expression and consequent activation of AdipoR1 could be regulated in response to exercise by the decrease in miR-221 expression in skeletal muscle of mice fed a high-fat diet. To test our hypothesis, we will use C57BL/6 mice fed on a high-fat diet ad libitum and subjected to a daily training program running belt. The animals will be divided into: control (C), trained control (TC), high-fat diet (H) and trained high-fat diet fed-mice (HT). At the end of 12 weeks of treatment, the mice will be tested for sensitivity to insulin (insulin tolerance test) and glucose (glucose tolerance test) and gastrocnemius muscles and blood samples will be collected for subsequent analysis. To evaluate the effect of exercise on the expression of AdipoR1 and miR-221, muscle samples will be homogenized, followed by determination of AdipoR1 and its controller PTB (RNA-binding protein tract-binding protein polypyrimidine) proteins content by Western Blotting. The expression of miR-221 will be assessed by q-PCR in all animal groups. The activation of AMPK, which is induced in response to AdipoR1 adiponectin signaling, will be checked in muscle samples by phosphorylation of AMPK. Furthermore, plasma adiponectin quantification will be performed in all groups. Then, this project will bring contributions to understanding exercise mechanisms that could improve insulin sensitivity through the modulation of AdipoR1, as well as miR-221 role in insulin resistant and trained animals. (AU)