Constitutive upregulations of titin-based signalling proteins in KY deficient muscles.

An increase in the expression of stretch/stress response elements in fast and slow muscles has been previously described in a transcriptional profiling of KY deficient muscles. Here, we have characterized the induction of this titin-based family of signalling proteins in ky/ky muscles at the protein level. Changes in expression of MLP, MARP2 and Xin have been related to the onset of dystrophic and adaptive changes that operate in ky/ky muscles. Our results indicate that induction of this set of genes is an early consequence of the interference caused by the absence of the KY protein. A search of muscle profiles of mouse models revealed such molecular hallmark only in muscles subjected to a single bout of eccentric contractions and specific titin mutants. Based on the role of this family as titin-based stress response molecules, it is suggested that titin structural/signalling instability is common to ky and titin mouse mutants and eccentric contractions.