APOPTOSIS AND TELOMERE REGULATION IN AGEING OF BOVINE SKELETAL MUSCLE

Introduction: In the normal ageing process, apoptosis has been implicated in sarcopenia (age-related muscle loss). Moreover, although the age-related shortening of telomere length (TL) is associated with cellular senescence, this mechanism is still partly unclear in a minimally proliferative tissue such as skeletal muscle. This study aimed to investigate TL and the age-related apoptotic changes in bovine skeletal muscle. Materials and Methods: Snap-frozen samples of skeletal muscle were collected from 42 pasture-raised cattle divided into three groups: aged, adult and young. For each group we evaluated the expression of cleaved caspase-3, p53 and X-linked inhibitor of apoptosis protein (XIAP) by immunohistochemistry; the number of apoptotic muscle cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) staining and TL by quantitative real-time PCR. Results: No expression of cleaved caspase 3 was observed in any group. The expression of p53 tended to change with age: a higher number of p53 immunolabelled muscle fibres and nuclei were observed in aged and mature animals compared with young animals and this was associated with an increase in the expression of apoptotic muscle cells and a decrease of XIAP expression. qPCR for telomere length evaluation did not reveal a significant difference among the three groups. Discussion: Taken together, our results suggest that apoptosis in skeletal muscle is possibly mediated through the expression of p53 and is not caspase-dependent. We also document that TL in bovine skeletal muscle seems to be unaffected by age, suggesting that chronological age does not affect the cellular ageing nor promote apoptosis in skeletal muscle