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Chondrogenic cell proliferation and signaling pathways induced by bioassayable growth hormone
Author(s) -
Gosselink Kristin L.,
Ramos Yamil,
Cooper Rasalin D.,
Herrera Gloria V.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.984.4
Subject(s) - cell growth , mapk/erk pathway , phosphorylation , chondrogenesis , microbiology and biotechnology , signal transduction , intracellular , cell signaling , tyrosine phosphorylation , bromodeoxyuridine , cell culture , in vitro , chemistry , endocrinology , biology , medicine , biochemistry , stem cell , genetics
Bioassayable growth hormone (BGH) was previously shown to stimulate growth of the tibial epiphyseal plate in rats in vivo, but the mechanisms contributing to this response have not been elucidated. The objective of this study, therefore, was to investigate the ability of BGH to induce cartilage proliferation in vitro, and examine the cellular signaling pathways responsible for this effect. The RCJ3.1C5.18 chondrogenic cell line was cultured to 10 days post‐confluence and stimulated with BGH‐containing plasma or conditioned media samples. Proliferation was measured by immunocytochemical staining for bromodeoxyuridine incorporation and quantified by cell counting. Intracellular protein fractions from control and stimulated cultures were isolated and subjected to Western blotting for phosphotyrosine, phosphoERK‐1/2 and phosphoMEK‐1/2. RCJ3.1C5.18 cell proliferation was significantly and dose‐dependently increased by BGH. BGH also increased the overall level of protein tyrosine phosphorylation, and elevated the cellular concentration of phosphorylated ERK‐1 and ERK‐2 in a dose‐dependent fashion. In addition, BGH enhanced the Ser/Thr phosphorylation of MEK‐2. The results demonstrate that BGH directly stimulates cartilage proliferation in vitro, and may utilize multiple signaling molecules to achieve this effect. Support: NIH/NCRR 5G12 RR008124 , NIH/NIGMS 5R25GM0490, NSF DBI‐0353887