title: The behaviour of satellite cells in response to exercise: what have we learned from human studies?
abstract: Understanding the complex role played by satellite cells in the adaptive response to exercise in human skeletal muscle has just begun. The development of reliable markers for the identification of satellite cell status (quiescence/activation/proliferation) is an important step towards the understanding of satellite cell behaviour in exercised human muscles. It is hypothesised currently that exercise in humans can induce (1) the activation of satellite cells without proliferation, (2) proliferation and withdrawal from differentiation, (3) proliferation and differentiation to provide myonuclei and (4) proliferation and differentiation to generate new muscle fibres or to repair segmental fibre injuries. In humans, the satellite cell pool can increase as early as 4 days following a single bout of exercise and is maintained at higher level following several weeks of training. Cessation of training is associated with a gradual reduction of the previously enhanced satellite cell pool. In the elderly, training counteracts the normal decline in satellite cell number seen with ageing. When the transcriptional activity of existing myonuclei reaches its maximum, daughter cells generated by satellite cell proliferation are involved in protein synthesis by enhancing the number of nuclear domains. Clearly, delineating the events and the mechanisms behind the activation of satellite cells both under physiological and pathological conditions in human skeletal muscles remains an important challenge.
authors.affiliation: Department of Physical Education and Health, Orebro University, Orebro, Sweden. fawzi.kadi@ioh.oru.se
authors.forename: Fawzi
authors.initials: F
authors.lastname: Kadi
authors.forename: Nadia
authors.initials: N
authors.lastname: Charifi
authors.forename: Christian
authors.initials: C
authors.lastname: Denis
authors.forename: Jan
authors.initials: J
authors.lastname: Lexell
authors.forename: Jesper L
authors.initials: JL
authors.lastname: Andersen
authors.forename: Peter
authors.initials: P
authors.lastname: Schjerling
authors.forename: Steen
authors.initials: S
authors.lastname: Olsen
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
mesh_terms: D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology; D049109:Cell Proliferation; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000166:cytology / Q000502:physiology; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development; D032496:Satellite Cells, Skeletal Muscle / Q000737:chemistry / Q000166:cytology / Q000502:physiology*
chemical_list: D015415:Biomarkers