MSM enhances GH signaling via the Jak2/STAT5b pathway in osteoblast-like cells and osteoblast differentiation through the activation of STAT5b in MSCs

PLoS One. 2012;7(10):e47477. doi: 10.1371/journal.pone.0047477. Epub 2012 Oct 11.

Abstract

Methylsulfonylmethane (MSM) is a naturally occurring sulfur compound with well-known anti-oxidant properties and anti-inflammatory activities. But, its effects on bone are unknown. Growth hormone (GH) is regulator of bone growth and bone metabolism. GH activates several signaling pathways such as the Janus kinase (Jak)/signal transducers and activators of transcription (STAT) pathway, thereby regulating expression of genes including insulin-like growth factor (IGF)-1. GH exerts effects both directly and via IGF-1, which signals by activating the IGF-1 receptor (IGF-1R). In this study, we investigated the effects of MSM on the GH signaling via the Jak/STAT pathway in osteoblasts and the differentiation of primary bone marrow mesenchymal stem cells (MSCs). MSM was not toxic to osteoblastic cells and MSCs. MSM increased the expression of GH-related proteins including IGF-1R, p-IGF-1R, STAT5b, p-STAT5b, and Jak2 in osteoblastic cells and MSCs. MSM increased IGF-1R and GHR mRNA expression in osteoblastic cells. The expression of MSM-induced IGF-1R and GHR was inhibited by AG490, a Jak2 kinase inhibitor. MSM induced binding of STAT5 to the IGF-1R and increased IGF-1 and IGF-1R promoter activities. Analysis of cell extracts by immunoprecipitation and Western blot showed that MSM enhanced GH-induced activation of Jak2/STAT5b. We found that MSM and GH, separately or in combination, activated GH signaling via the Jak2/STAT5b pathway in UMR-106 cells. Using siRNA analysis, we found that STAT5b plays an essential role in GH signaling activation in C3H10T1/2 cells. Osteogenic marker genes (ALP, ON, OCN, BSP, OSX, and Runx2) were activated by MSM, and siRNA-mediated STAT5b knockdown inhibited MSM-induced expression of osteogenic markers. Furthermore, MSM increased ALP activity and the mineralization of MSCs. Taken together, these results indicated that MSM can promote osteogenic differentiation of MSCs through activation of STAT5b.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Blotting, Western
  • Cell Differentiation / physiology
  • Cell Line, Tumor
  • DNA Primers / genetics
  • Dimethyl Sulfoxide / pharmacology*
  • Electrophoretic Mobility Shift Assay
  • Growth Hormone / metabolism*
  • Immunoprecipitation
  • Janus Kinase 2 / metabolism*
  • Luciferases
  • Mesenchymal Stem Cells / metabolism
  • Osteoblasts / metabolism
  • Osteoblasts / physiology
  • Osteogenesis / drug effects*
  • RNA, Small Interfering / genetics
  • Rats
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • STAT5 Transcription Factor / metabolism*
  • Signal Transduction / drug effects*
  • Sulfones / pharmacology*
  • Tetrazolium Salts
  • Thiazoles

Substances

  • DNA Primers
  • RNA, Small Interfering
  • STAT5 Transcription Factor
  • Stat5b protein, rat
  • Sulfones
  • Tetrazolium Salts
  • Thiazoles
  • Growth Hormone
  • dimethyl sulfone
  • Luciferases
  • Jak2 protein, rat
  • Janus Kinase 2
  • thiazolyl blue
  • Dimethyl Sulfoxide

Grant support

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0004568), and was partially supported by a grant from the Fundamental R&D Program for Technology of World Premier Materials funded by the Ministry of Knowledge Economy, Republic of Korea. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.