Preliminary investigation of skeletal muscle signal recognition particle receptor beta in response to aging in the rat

Abstract

The signal recognition particle receptor (SRPR) interacts with the signal recognition particle (SRP), which targets and transports nacent polypeptides destined for secretion or expression on the cell membrane. The SRP is likely important for normal muscle functioning since individuals with autoantibody production against the SRP can develop myopathy. The SRPR contains two subunits; one of which is the beta subunit that is integrated within the membrane of the endoplasmic reticulum (ER). We became interested in SRPR beta after an initial proteomic screening indicated altered expression of the protein in aged muscle. The objective of the current experiment was to further examine skeletal muscle SRPR beta protein expression in response to aging. We harvested extensor digitorum longus muscles from 8, 28, and 36‐ month old male Fisher 344xBrown Norway F1 hybrid rats (n = 4/group). Protein expression of SRPR beta was assessed using Western blot and was approximately 60% lower in the 36‐month old rats compared to younger animals (8‐month old group = 0.20 ± 0.04, 28‐month old group = 0.21 ± 0.05, 36‐month old group = 0.09 ± 0.03; values are mean ± SEM). This preliminary investigation is the first to examine SRPR protein expression in aging skeletal muscle and the findings suggest changes in SRPR beta may be associated with skeletal muscle alterations that occur in old age.Supported by NIH 5R03AG032033 (KCD).