Muscle strength declines with age in part due to a decline of Ca2+ release from sarcoplasmic reticulum calcium stores. Skeletal muscle dihydropyridine receptors (Cav1.1) initiate muscle contraction by activating ryanodine receptors in the sarcoplasmic reticulum. Cav1.1 channel activity is enhanced by a retrograde stimulatory signal delivered by the ryanodine receptor. JP45 is a membrane protein interacting with Cav1.1 and the sarcoplasmic reticulum Ca2+ storage protein calsequestrin (CASQ1). Here we show that JP45 and CASQ1 strengthen skeletal muscle contraction by modulating Cav1.1 channel activity. Using muscle fibres from JP45 and CASQ1 double knockout mice, we demonstrate that Ca2+ transients evoked by tetanic stimulation are the result of massive Ca2+ influx due to enhanced Cav1.1 channel activity, which restores muscle strength in JP45/CASQ1 double knockout mice. We envision that JP45 and CASQ1 may be candidate targets for the development of new therapeutic strategies against decay of skeletal muscle strength caused by a decrease in sarcoplasmic reticulum Ca2+ content.
Enhanced dihydropyridine receptor calcium channel activity restores muscle strength in JP45/CASQ1 double knockout mice.
MOSCA, Barbara;BERGAMELLI, Leda;TREVES, Susan Nella;MARTINI, Marta;RISPOLI, Giorgio;ZORZATO, Francesco
2013
Abstract
Muscle strength declines with age in part due to a decline of Ca2+ release from sarcoplasmic reticulum calcium stores. Skeletal muscle dihydropyridine receptors (Cav1.1) initiate muscle contraction by activating ryanodine receptors in the sarcoplasmic reticulum. Cav1.1 channel activity is enhanced by a retrograde stimulatory signal delivered by the ryanodine receptor. JP45 is a membrane protein interacting with Cav1.1 and the sarcoplasmic reticulum Ca2+ storage protein calsequestrin (CASQ1). Here we show that JP45 and CASQ1 strengthen skeletal muscle contraction by modulating Cav1.1 channel activity. Using muscle fibres from JP45 and CASQ1 double knockout mice, we demonstrate that Ca2+ transients evoked by tetanic stimulation are the result of massive Ca2+ influx due to enhanced Cav1.1 channel activity, which restores muscle strength in JP45/CASQ1 double knockout mice. We envision that JP45 and CASQ1 may be candidate targets for the development of new therapeutic strategies against decay of skeletal muscle strength caused by a decrease in sarcoplasmic reticulum Ca2+ content.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
