Protective role of alpha-actinin-3 in the response to an acute eccentric exercise bout
(2010) Journal of Applied Physiology — Vol. 109, n° 2, p. 564-573 (2010)
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- Vincent B, Windelinckx A, Nielens H, Ramaekers M, Van Leemputte M, Hespel P, Thomis MA. Protective role of alpha-actinin-3 in the response to an acute eccentric exercise bout. J Appl Physiol 109: 564-573, 2010. First published May 27, 2010; doi: 10.1152/japplphysiol.01007.2009.-The ACTN3 gene encodes for the alpha-actinin-3 protein, which has an important structural function in the Z line of the sarcomere in fast muscle fibers. A premature stop codon (R577X) polymorphism in the ACTN3 gene causes a complete loss of the protein in XX homozygotes. This study investigates a possible role for the alpha-actinin-3 protein in protecting the fast fiber from eccentric damage and studies repair mechanisms after a single eccentric exercise bout. Nineteen healthy young men (10 XX, 9 RR) performed 4 series of 20 maximal eccentric knee extensions with both legs. Blood (creatine kinase; CK) and muscle biopsy samples were taken to study differential expression of several anabolic (MyoD1, myogenin, MRF4, Myf5, IGF-1), catabolic (myostatin, MAFbx, and MURF-1), and contraction-induced muscle damage marker genes [cysteine-and glycine-rich protein 3 (CSRP3), CARP, HSP70, and IL-6] as well as a calcineurin signaling pathway marker (RCAN1). Baseline mRNA content of CSRP3 and MyoD1 was 49 +/- 12 and 67 +/- 25% higher in the XX compared with the RR group (P = 0.01-0.045). However, satellite cell number was not different between XX and RR individuals. After eccentric exercise, XX individuals tended to have higher serum CK activity (P = 0.10) and had higher pain scores than RR individuals. However, CSRP3 (P = 0.058) and MyoD1 (P = 0.08) mRNA expression tended to be higher after training in RR individuals compared with XX alpha-actinin-3-deficient subjects. This study suggests a protective role of alpha-actinin-3 protein in muscle damage after eccentric training and an improved stress-sensor signaling, although effects are small.
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Vincent, B., Windelinckx, A., Nielens, H., Ramaekers, M., Van Leemputte, M., Hespel, P., & Thomis, M. A. (2010). Protective role of alpha-actinin-3 in the response to an acute eccentric exercise bout. Journal of Applied Physiology, 109(2), 564-573. https://doi.org/10.1152/japplphysiol.01007.2009 (Original work published 2010)