Hypoxia affects positively the proliferation of bovine satellite cells and their myogenic differentiation through up-regulation of MyoD.
Hypoxia alters the biological functions of skeletal muscle cells to proliferate and differentiate into myotubes. However, the cellular responses of myoblasts to hypoxia differ according to the levels of oxygen and the types of cells studied. This study examined the effect of hypoxia (1% oxygen) on bovine satellite cells. Hypoxia significantly increased the proliferation of satellite cells cultured in a growth medium. In addition, the levels of PCNA, cyclin D1, cyclin-dependent kinase-1 (CDK1) and CDK2 expression were increased. Hypoxia facilitated the formation of myotubes as well as the stimulation of MyoD, myogenin, and myosin heavy chain (MHC) expression in differentiating medium (DM) cultures. In particular, satellite cells cultured under hypoxic/DM conditions showed increased p21 expression but not p27. The transfection of satellite cells with antisense MyoD oligonucleotides resulted in a decrease in the MHC, myogenin, MRF4 RNA and protein levels with the concomitant decrease in fused cells to levels similar to those observed under normoxia/DM conditions. This indicates that MyoD up-regulation is closely associated with hypoxia-stimulated myogenic differentiation. In conclusion, hypoxia stimulates the proliferation of satellite cells and promotes their myogenic differentiation with MyoD playing an important role.
Kook
Sung-Ho
SH
Division of Biological Sciences, Institute of Oral Biosciences, Chonbuk National University, Jeonju 561-756, Republic of Korea.
Son
Young-Ok
YO
Lee
Kyung-Yeol
KY
Lee
Hyun-Jeong
HJ
Chung
Wan-Tae
WT
Choi
Ki-Choon
KC
Lee
Jeong-Chae
JC
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002417:Cattle; D002453:Cell Cycle; D002454:Cell Differentiation; D015687:Cell Hypoxia; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D017570:MyoD Protein / Q000378:metabolism*; D032446:Myoblasts / Q000378:metabolism; D018008:Myogenin / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology* / Q000378:metabolism; D015854:Up-Regulation; D054462:p21-Activated Kinases / Q000378:metabolism
D017570:MyoD Protein; D018008:Myogenin; D018809:Proliferating Cell Nuclear Antigen; D019938:Cyclin D1; D054462:p21-Activated Kinases; D016203:CDC2 Protein Kinase; D051357:Cyclin-Dependent Kinase 2; D018995:Myosin Heavy Chains