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Title: Ornithine decarboxylase is upregulated by the androgen receptor in skeletal muscle and regulates myoblast proliferation.
Austin Authors: Lee, Nicole K L;Skinner, Jarrod P J;Zajac, Jeffrey D ;MacLean, Helen E
Affiliation: Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
Issue Date: 19-Apr-2011
Publication information: American Journal of Physiology. Endocrinology and Metabolism 2011; 301(1): E172-9
Abstract: The aim of this study is to determine if the Odc1 gene, which encodes ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, is directly regulated by the androgen receptor (AR) in skeletal muscle myoblasts and if Odc1 regulates myoblast proliferation and differentiation. We previously showed that expression of Odc1 is decreased in muscle from AR knockout male mice. In this study, we show in vivo that Odc1 expression is also decreased >60% in muscle from male muscle-specific AR knockout mice. In normal muscle homeostasis, Odc1 expression is regulated by age and sex, reflecting testosterone levels, as muscle of adult male mice expresses high levels of Odc1 compared with age-matched females and younger males. In vitro, expression of Odc1 is 10- and 1.5-fold higher in proliferating mouse C(2)C(12) and human skeletal muscle myoblasts, respectively, than in differentiated myotubes. Dihydrotestosterone increases Odc1 levels 2.7- and 1.6-fold in skeletal muscle cell myoblasts after 12 and 24 h of treatment, respectively. Inhibition of ODC activity in C(2)C(12) myoblasts by α-difluoromethylornithine decreases myoblast number by 40% and 66% following 48 and 72 h of treatment, respectively. In contrast, overexpression of Odc1 in C(2)C(12) myoblasts results in a 27% increase in cell number vs. control when cells are grown under differentiation conditions for 96 h. This prolonged proliferation is associated with delayed differentiation, with reduced expression of the differentiation markers myogenin and Myf6 in Odc1-overexpressing cells. In conclusion, androgens act via the AR to upregulate Odc1 in skeletal muscle myoblasts, and Odc1 promotes myoblast proliferation and delays differentiation.
Gov't Doc #: 21505150
DOI: 10.1152/ajpendo.00094.2011
Journal: American journal of physiology. Endocrinology and metabolism
Type: Journal Article
Subjects: Androgens.pharmacology
Cell Differentiation.drug effects
Cell Proliferation.drug effects
Cells, Cultured
Embryo, Mammalian
Gene Expression Regulation, Enzymologic.drug effects
Mice, Inbred C57BL
Mice, Transgenic
Muscle, Skeletal.drug effects.metabolism.physiology
Myoblasts, Skeletal.drug effects.metabolism.physiology
Ornithine Decarboxylase.genetics.metabolism
Receptors, Androgen.metabolism.physiology
Up-Regulation.drug effects
Appears in Collections:Journal articles

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