title: The hypoxia-inducible factors HIF1α and HIF2α are dispensable for embryonic muscle development but essential for postnatal muscle regeneration.
abstract: Muscle satellite cells are myogenic stem cells whose quiescence, activation, self-renewal, and differentiation are influenced by oxygen supply, an environmental regulator of stem cell activity. Accordingly, stem cell-specific oxygen signaling pathways precisely control the balance between muscle growth and regeneration in response to oxygen fluctuations, and hypoxia-inducible factors (HIFs) are central mediators of these cellular responses. However, thein vivoroles of HIFs in quiescent satellite cells and activated satellite cells (myoblasts) are poorly understood. Using transgenic mouse models for cell-specific HIF expression, we show here that HIF1α and HIF2α are preferentially expressed in pre- and post-differentiation myoblasts, respectively. Interestingly, double knockouts of HIF1α and HIF2α (HIF1α/2α dKO) generated with the MyoDCresystem in embryonic myoblasts resulted in apparently normal muscle development and growth. However, HIF1α/2α dKO produced with the tamoxifen-inducible, satellite cell-specific Pax7CreERsystem in postnatal satellite cells delayed injury-induced muscle repair due to a reduced number of myoblasts during regeneration. Analysis of satellite cell dynamics on myofibers confirmed that HIF1α/2α dKO myoblasts exhibit reduced self-renewal but more pronounced differentiation under hypoxic conditions. Mechanistically, the HIF1α/2α dKO blunted hypoxia-induced activation of Notch signaling, a key determinant of satellite cell self-renewal. We conclude that HIF1α and HIF2α are dispensable for muscle stem cell function under normoxia but are required for maintaining satellite cell self-renewal in hypoxic environments. Our insights into a critical mechanism in satellite cell homeostasis during muscle regeneration could help inform research efforts to treat muscle diseases or improve muscle function.
authors.affiliation: From the Department of Animal Science, Purdue University and.
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.affiliation: From the Department of Animal Science, Purdue University and.
authors.forename: Shiqi
authors.initials: S
authors.lastname: Yang
authors.affiliation: From the Department of Animal Science, Purdue University and.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: From the Department of Animal Science, Purdue University and skuang@purdue.edu.|Purdue University Center for Cancer Research, West Lafayette, Indiana 47907.
authors.forename: Shihuan
authors.initials: S
authors.lastname: Kuang
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D024510:Muscle Development / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology*; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000378:metabolism*; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017570:MyoD Protein; D000099162:Endothelial PAS Domain-Containing Protein 1; C497443:Hif1a protein, mouse; C057363:MyoD1 myogenic differentiation protein
keywords: Notch pathway; development; hypoxia; hypoxia-inducible factor (HIF); muscle regeneration