The muscle ankyrin repeat proteins: CARP, ankrd2/Arpp and DARP as a family of titin filament-based stress response molecules

MK Miller, ML Bang, CC Witt, D Labeit… - Journal of molecular …, 2003 - Elsevier
MK Miller, ML Bang, CC Witt, D Labeit, C Trombitas, K Watanabe, H Granzier, AS McElhinny…
Journal of molecular biology, 2003Elsevier
CARP, ankrd-2/Arpp, and DARP, are three members of a conserved gene family, referred to
here as MARPs (muscle ankyrin repeat proteins). The expression of MARPs is induced upon
injury and hypertrophy (CARP), stretch or denervation (ankrd2/Arpp), and during recovery
following starvation (DARP), suggesting that they are involved in muscle stress response
pathways. Here, we show that MARP family members contain within their ankyrin repeat
region a binding site for the myofibrillar elastic protein titin. Within the myofibril, MARPs …
CARP, ankrd-2/Arpp, and DARP, are three members of a conserved gene family, referred to here as MARPs (muscle ankyrin repeat proteins). The expression of MARPs is induced upon injury and hypertrophy (CARP), stretch or denervation (ankrd2/Arpp), and during recovery following starvation (DARP), suggesting that they are involved in muscle stress response pathways. Here, we show that MARP family members contain within their ankyrin repeat region a binding site for the myofibrillar elastic protein titin. Within the myofibril, MARPs, myopalladin, and the calpain protease p94 appear to be components of a titin N2A-based signaling complex. Ultrastructural studies demonstrated that all three endogenous MARP proteins co-localize with I-band titin N2A epitopes in adult heart muscle tissues. In cultured fetal rat cardiac myocytes, passive stretch induced differential distribution patterns of CARP and DARP: staining for both proteins was increased in the nucleus and at the I-band region of myofibrils, while DARP staining also increased at intercalated discs. We speculate that the myofibrillar MARPs are regulated by stretch, and that this links titin-N2A-based myofibrillar stress/strain signals to a MARP-based regulation of muscle gene expression.
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