Small heat shock proteins translocate to the cytoskeleton in human skeletal muscle following eccentric exercise independently of phosphorylation.
Small heat shock proteins (sHSPs) are a subgroup of the highly conserved family of HSPs that are stress inducible and confer resistance to cellular stress and injury. This study aimed to quantitatively examine whether type of contraction (concentric or eccentric) affects sHSPs, HSP27 and αB-crystallin, localization, and phosphorylation in human muscle. Vastus lateralis muscle biopsies from 11 healthy male volunteers were obtained pre- and 3 h, 24 h, and 7 days following concentric (CONC), eccentric (ECC1), and repeated bout eccentric (ECC2) exercise. No changes were apparent in a control group (n = 5) who performed no exercise. Eccentric exercise induced muscle damage, as evidenced by increased muscle force loss, perceived muscle soreness, and elevated plasma creatine kinase and myoglobin levels. Total HSP27 and αB-crystallin amounts did not change following any type of exercise. Following eccentric exercise (ECC1 and ECC2) phosphorylation of HSP27 at serine 15 (pHSP27-Ser15) was increased approximately 3- to 6-fold at 3 h, and pαB-crystallin-Ser59 increased ~10-fold at 3 h. Prior to exercise most of the sHSP and psHSP pools were present in the cytosolic compartment. Eccentric exercise resulted in partial redistribution of HSP27 (~23%) from the cytosol to the cytoskeletal fraction (~28% for pHSP27-Ser15 and ~7% for pHSP27-Ser82), with subsequent full reversal within 24 h. αB-crystallin also showed partial redistribution from the cytosolic to cytoskeletal fraction (~18% of total) 3 h post-ECC1, but not after ECC2. There was no redistribution or phosphorylation of sHSPs with CONC. Eccentric exercise results in increased sHSP phosphorylation and translocation to the cytoskeletal fraction, but the sHSP translocation is not dependent on their phosphorylation.
Department of Zoology, La Trobe University, Melbourne, Victoria, Australia; and.
Noni T
NT
Frankenberg
Department of Zoology, La Trobe University, Melbourne, Victoria, Australia; and.
Graham D
GD
Lamb
Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
Kristian
K
Overgaard
Department of Zoology, La Trobe University, Melbourne, Victoria, Australia; and r.murphy@latrobe.edu.au.
Robyn M
RM
Murphy
Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
Kristian
K
Vissing
D000222:Adaptation, Physiological / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008297:Male; D008970:Molecular Weight; D009119:Muscle Contraction / Q000502:physiology*; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology*; D010766:Phosphorylation; D064797:Physical Conditioning, Human / Q000379:methods; D021381:Protein Transport / Q000502:physiology; D055815:Young Adult
D003598:Cytoskeletal Proteins; D006360:Heat-Shock Proteins; D009124:Muscle Proteins
HSP27; eccentric exercise; phosphorylation; single fibers; αB-crystallin