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Cell Biology International (2008) 32, 871878 (Printed in Great Britain)
Hypoxia affects positively the proliferation of bovine satellite cells and their myogenic differentiation through up-regulation of MyoD
Sung‑Ho Kookab, Young‑Ok Sonbc, Kyung‑Yeol Leebc, Hyun‑Jeong Leed, Wan‑Tae Chungd, Ki‑Choon Choie and Jeong‑Chae Leebc*
aDivision of Biological Sciences, Chonbuk National University, Jeonju 561-756, Republic of Korea
bInstitute of Oral Biosciences, Chonbuk National University, Jeonju 561-756, Republic of Korea
cResearch Center of Bioactive Materials, Chonbuk National University, Duckjin-Dong 664-14, Jeonju 561-756, Republic of Korea
dNational Livestock Research Institute, RDA, Suweon 441-706, Republic of Korea
eDivision of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Korea University, Seoul 152-050, Republic of Korea
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.
Key words: Bovine satellite cells, Hypoxia, Proliferation, Differentiation, MRFs.
*Corresponding author. Research Center of Bioactive Materials, Chonbuk National University, Jeonju 561-756, Republic of Korea. Tel./fax: +82 63 270 4049.
Received 3 November 2007/21 December 2007; accepted 28 March 2008doi:10.1016/j.cellbi.2008.03.017