Mitogen activated protein kinase-dependent inhibition of osteocalcin gene expression by transforming growth factor-β1

Sukyee Kwok, Nicola Partridge, Narasaimhan Srinivasan, Shantikumar V. Nair, Nagarajan Selvamurugan

Research output: Contribution to journalArticle

Abstract

TGF-β (transforming growth factor-beta) plays a key role in osteoblast differentiation and bone development. While the ability of TGF-β to inhibit the expression of osteoblast differentiation genes has been well documented, the mechanism of this inhibition is not yet completely characterized. Runx2, a transcription factor necessary for expression of osteoblast differentiation genes is a central target of inhibition by TGF-β. In this study, we found that TGF-β1 inhibits expression of osteoblast differentiation genes without altering expression of Runx2. Transient transfection experiments determined that TGF-β1 inhibited osteocalcin promoter activity and this effect is mediated through Runx2. We further identified that there was no change in protein expression, cellular localization, or DNA binding affinity of Runx2 after TGF-β1-treatment of osteoblasts, suggesting that Runx2 undergoes post-translational modifications following TGF-β1 treatment. Coimmunoprecipitation experiments identified increased phosphorylation of Runx2 when differentiating osteoblasts were treated with TGF-β1. Mitogen activated protein kinase (MAPK) inhibitors relieved the TGF-β1-inhibitory effect of Runx2-mediated osteocalcin expression. Thus, our results suggest that TGF-β1-inhibition of osteoblast differentiation is dependent on the MAPK pathway and this effect is most likely mediated by post-translational modification of Runx2 such as phosphorylation rather than other regulatory mechanisms. J. Cell. Biochem. 106: 161-169, 2009. copy; 2008 Wiley-Liss, Inc.

Original languageEnglish (US)
Pages (from-to)161-169
Number of pages9
JournalJournal of Cellular Biochemistry
Volume106
Issue number1
DOIs
StatePublished - Jan 1 2009

Fingerprint

Osteocalcin
Transforming Growth Factors
Mitogen-Activated Protein Kinases
Gene expression
Transforming Growth Factor beta
Osteoblasts
Gene Expression
Phosphorylation
Genes
Post Translational Protein Processing
Bone Development
Protein Kinase Inhibitors
Transfection
Bone
Transcription Factors
Experiments
DNA

Keywords

  • Osteoblast
  • Osteocalcin
  • Runx2
  • Tgf-β

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Mitogen activated protein kinase-dependent inhibition of osteocalcin gene expression by transforming growth factor-β1. / Kwok, Sukyee; Partridge, Nicola; Srinivasan, Narasaimhan; Nair, Shantikumar V.; Selvamurugan, Nagarajan.

In: Journal of Cellular Biochemistry, Vol. 106, No. 1, 01.01.2009, p. 161-169.

Research output: Contribution to journalArticle

Kwok, Sukyee ; Partridge, Nicola ; Srinivasan, Narasaimhan ; Nair, Shantikumar V. ; Selvamurugan, Nagarajan. / Mitogen activated protein kinase-dependent inhibition of osteocalcin gene expression by transforming growth factor-β1. In: Journal of Cellular Biochemistry. 2009 ; Vol. 106, No. 1. pp. 161-169.
@article{515adefa130d47dd9087e22d9493f1d8,
title = "Mitogen activated protein kinase-dependent inhibition of osteocalcin gene expression by transforming growth factor-β1",
abstract = "TGF-β (transforming growth factor-beta) plays a key role in osteoblast differentiation and bone development. While the ability of TGF-β to inhibit the expression of osteoblast differentiation genes has been well documented, the mechanism of this inhibition is not yet completely characterized. Runx2, a transcription factor necessary for expression of osteoblast differentiation genes is a central target of inhibition by TGF-β. In this study, we found that TGF-β1 inhibits expression of osteoblast differentiation genes without altering expression of Runx2. Transient transfection experiments determined that TGF-β1 inhibited osteocalcin promoter activity and this effect is mediated through Runx2. We further identified that there was no change in protein expression, cellular localization, or DNA binding affinity of Runx2 after TGF-β1-treatment of osteoblasts, suggesting that Runx2 undergoes post-translational modifications following TGF-β1 treatment. Coimmunoprecipitation experiments identified increased phosphorylation of Runx2 when differentiating osteoblasts were treated with TGF-β1. Mitogen activated protein kinase (MAPK) inhibitors relieved the TGF-β1-inhibitory effect of Runx2-mediated osteocalcin expression. Thus, our results suggest that TGF-β1-inhibition of osteoblast differentiation is dependent on the MAPK pathway and this effect is most likely mediated by post-translational modification of Runx2 such as phosphorylation rather than other regulatory mechanisms. J. Cell. Biochem. 106: 161-169, 2009. copy; 2008 Wiley-Liss, Inc.",
keywords = "Osteoblast, Osteocalcin, Runx2, Tgf-β",
author = "Sukyee Kwok and Nicola Partridge and Narasaimhan Srinivasan and Nair, {Shantikumar V.} and Nagarajan Selvamurugan",
year = "2009",
month = "1",
day = "1",
doi = "10.1002/jcb.21991",
language = "English (US)",
volume = "106",
pages = "161--169",
journal = "Journal of Cellular Biochemistry",
issn = "0730-2312",
publisher = "Wiley-Liss Inc.",
number = "1",

}

TY - JOUR

T1 - Mitogen activated protein kinase-dependent inhibition of osteocalcin gene expression by transforming growth factor-β1

AU - Kwok, Sukyee

AU - Partridge, Nicola

AU - Srinivasan, Narasaimhan

AU - Nair, Shantikumar V.

AU - Selvamurugan, Nagarajan

PY - 2009/1/1

Y1 - 2009/1/1

N2 - TGF-β (transforming growth factor-beta) plays a key role in osteoblast differentiation and bone development. While the ability of TGF-β to inhibit the expression of osteoblast differentiation genes has been well documented, the mechanism of this inhibition is not yet completely characterized. Runx2, a transcription factor necessary for expression of osteoblast differentiation genes is a central target of inhibition by TGF-β. In this study, we found that TGF-β1 inhibits expression of osteoblast differentiation genes without altering expression of Runx2. Transient transfection experiments determined that TGF-β1 inhibited osteocalcin promoter activity and this effect is mediated through Runx2. We further identified that there was no change in protein expression, cellular localization, or DNA binding affinity of Runx2 after TGF-β1-treatment of osteoblasts, suggesting that Runx2 undergoes post-translational modifications following TGF-β1 treatment. Coimmunoprecipitation experiments identified increased phosphorylation of Runx2 when differentiating osteoblasts were treated with TGF-β1. Mitogen activated protein kinase (MAPK) inhibitors relieved the TGF-β1-inhibitory effect of Runx2-mediated osteocalcin expression. Thus, our results suggest that TGF-β1-inhibition of osteoblast differentiation is dependent on the MAPK pathway and this effect is most likely mediated by post-translational modification of Runx2 such as phosphorylation rather than other regulatory mechanisms. J. Cell. Biochem. 106: 161-169, 2009. copy; 2008 Wiley-Liss, Inc.

AB - TGF-β (transforming growth factor-beta) plays a key role in osteoblast differentiation and bone development. While the ability of TGF-β to inhibit the expression of osteoblast differentiation genes has been well documented, the mechanism of this inhibition is not yet completely characterized. Runx2, a transcription factor necessary for expression of osteoblast differentiation genes is a central target of inhibition by TGF-β. In this study, we found that TGF-β1 inhibits expression of osteoblast differentiation genes without altering expression of Runx2. Transient transfection experiments determined that TGF-β1 inhibited osteocalcin promoter activity and this effect is mediated through Runx2. We further identified that there was no change in protein expression, cellular localization, or DNA binding affinity of Runx2 after TGF-β1-treatment of osteoblasts, suggesting that Runx2 undergoes post-translational modifications following TGF-β1 treatment. Coimmunoprecipitation experiments identified increased phosphorylation of Runx2 when differentiating osteoblasts were treated with TGF-β1. Mitogen activated protein kinase (MAPK) inhibitors relieved the TGF-β1-inhibitory effect of Runx2-mediated osteocalcin expression. Thus, our results suggest that TGF-β1-inhibition of osteoblast differentiation is dependent on the MAPK pathway and this effect is most likely mediated by post-translational modification of Runx2 such as phosphorylation rather than other regulatory mechanisms. J. Cell. Biochem. 106: 161-169, 2009. copy; 2008 Wiley-Liss, Inc.

KW - Osteoblast

KW - Osteocalcin

KW - Runx2

KW - Tgf-β

UR - http://www.scopus.com/inward/record.url?scp=58649086311&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=58649086311&partnerID=8YFLogxK

U2 - 10.1002/jcb.21991

DO - 10.1002/jcb.21991

M3 - Article

VL - 106

SP - 161

EP - 169

JO - Journal of Cellular Biochemistry

JF - Journal of Cellular Biochemistry

SN - 0730-2312

IS - 1

ER -