Role of E3 ligases on skeletal muscle plasticity.

Author(s)

Igor Luchini Baptista

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2012-11-14

Examining board members

Anselmo Sigari Moriscot; Vanessa Morais Freitas; Maria Julia Marques; Maeli Dal Pai Silva; Chao Yun Irene Yan

• Advisor: Anselmo Sigari Moriscot

Abstract

In the present thesis we analyzed the involvement of E3 ligases under three aspects of skeletal muscle plasticity: mass loss resulting from disuse, maintenance of fiber type I and II and regeneration of muscle tissue. Our first aim was to determine whether leucine, was able to attenuate the mass loss caused by wasting. Our results showed that this amino acid prevented the mass loss, mainly by inhibiting the expression of E3 ligases. The second aim was to determine whether the absence of two E3 ligases, MuRF1 and MuRF2, could alter the proportion of type I and type II fibers. We found that in the absence of these E3 ligases, the identity of type II fibers was lost, and these fibers were protected against atrophy in the absence of MuRF1. Lastly, we analyze the role of MuRF1 and MuRF2 in muscle tissue regeneration. The results showed that these E3 ligases together are crucial to satellite-cells physiology and consequently an adequate tissue regeneration. This thesis show that certain E3 ligases can play a crucial role in muscle plasticity. (AU)