Morpho-functional characterization of Transportin3 in myogenic differentiation of a cell model of LGMD D2.

Limb Girdle Muscular Dystrophy D2 (LGMD D2) is caused by a heterozygous mutation in the termination codon of the TNPO3 gene. This mutation gives a protein which is 15-aminoacids longer in its C-terminal domain. TNPO3 gene encodes for TNPO3, which normally mediates the translocation to the nucleus of SR proteins, a family of splicing factors and other proteins related to RNA metabolism. Recently a relationship among TNPO3 mutation and alteration in myogenic pathways has been suggested. The goal of this work was to investigate the pathogenetic mechanism of LGMD D2 creating a cell model of disease in which would be possible to study the role of TNPO3 in the myogenic process and in possible muscle-specific molecular pathways. Murine C2C12 myoblasts were transfected with a plasmid carring respectively the wild type (WT) or the mutated (MUT) sequence of TNPO3. We monitored the gene and protein expression profiles of TNPO3, of myogenic regulatory factors (MRFs), myomiRNA and muscle-specific proteins. Preliminary data suggest morphological and expression changes of genes and proteins involved in myogenic differentiation in comparison to the C2C12 control line. The approach used is a first step to understand the role of TNPO3 in muscle physiology and in the pathogenetic mechanism underlying LGMD D2 which is still unknown. [ABSTRACT FROM AUTHOR]