Reconstitution of Runx2/Cbfa1-null cells identifies a requirement for BMP2 signaling through a Runx2 functional domain during osteoblast differentiation

Jong Sup Bae, Soraya Gutierrez, Radhika Narla, Jitesh Pratap, Rajitha Devados, Andre J van Wijnen, Janet L. Stein, Gary S. Stein, Jane B. Lian, Amjad Javed

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

The Runx2/Cbfa1 transcription factor is a scaffolding protein that promotes osteoblast differentiation; however, the specific Runx2-functional domains required for induction of the osteogenic lineage remain to be identified. We approached this question using a TERT-immortalized cell line derived from calvaria of Runx2-null mice by reconstituting the osteogenic activity with wild-type and deletion mutants of Runx2. The presence or absence of osteogenic media (β-glycerol phosphate and ascorbic acid) and/or with BMP2 did not stimulate osteoblastic gene expression in the Runx2-null cells. However, cells infected with wild-type Runx2 adenovirus showed a robust temporal increase in the expression of osteoblast marker genes and were competent to respond to BMP2. Early markers (i.e., collagen type-1, alkaline phosphatase) were induced (four- to eightfold) at Days 4 and 8 of culture. Genes representing mature osteoblasts (e.g., Runx2, osteopontin, bone sialoprotein, osteocalcin) were temporally expressed and induced from 18-to 36-fold at Days 8 and 12. Interestingly, TGFβ and Vitamin D-mediated transcription of osteoblast genes (except for osteopontin) required the presence of Runx2. Runx2 lacking the C-terminal 96 amino acids (Runx2 Δ432) showed a pattern of gene expression similar to wild-type protein, demonstrating the Groucho interaction and part of the activation domain are dispensable for Runx2 osteogenic activity. Upon further deletion of the Runx2 C-terminus containing the nuclear matrix targeting signal and Smad-interacting domain (Δ391), we find none of the osteoblast markers are expressed. Therefore, the Runx2 391-432 domain is essential for execution of the BMP2 osteogenic signal.

Original languageEnglish (US)
Pages (from-to)434-449
Number of pages16
JournalJournal of Cellular Biochemistry
Volume100
Issue number2
DOIs
StatePublished - Feb 1 2007
Externally publishedYes

Fingerprint

Null Lymphocytes
Osteoblasts
Osteopontin
Genes
Gene expression
Integrin-Binding Sialoprotein
Gene Expression
Nuclear Matrix
Osteocalcin
Transcription
Collagen Type I
Cell culture
Adenoviridae
Skull
Vitamin D
Glycerol
Ascorbic Acid
Alkaline Phosphatase
Proteins
Transcription Factors

Keywords

  • 1,25(OH)D
  • BMP2/TGFβ osteogenic signaling
  • Runx2
  • Transcriptional regulation

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology

Cite this

Reconstitution of Runx2/Cbfa1-null cells identifies a requirement for BMP2 signaling through a Runx2 functional domain during osteoblast differentiation. / Bae, Jong Sup; Gutierrez, Soraya; Narla, Radhika; Pratap, Jitesh; Devados, Rajitha; van Wijnen, Andre J; Stein, Janet L.; Stein, Gary S.; Lian, Jane B.; Javed, Amjad.

In: Journal of Cellular Biochemistry, Vol. 100, No. 2, 01.02.2007, p. 434-449.

Research output: Contribution to journalArticle

Bae, JS, Gutierrez, S, Narla, R, Pratap, J, Devados, R, van Wijnen, AJ, Stein, JL, Stein, GS, Lian, JB & Javed, A 2007, 'Reconstitution of Runx2/Cbfa1-null cells identifies a requirement for BMP2 signaling through a Runx2 functional domain during osteoblast differentiation', Journal of Cellular Biochemistry, vol. 100, no. 2, pp. 434-449. https://doi.org/10.1002/jcb.21039
Bae, Jong Sup ; Gutierrez, Soraya ; Narla, Radhika ; Pratap, Jitesh ; Devados, Rajitha ; van Wijnen, Andre J ; Stein, Janet L. ; Stein, Gary S. ; Lian, Jane B. ; Javed, Amjad. / Reconstitution of Runx2/Cbfa1-null cells identifies a requirement for BMP2 signaling through a Runx2 functional domain during osteoblast differentiation. In: Journal of Cellular Biochemistry. 2007 ; Vol. 100, No. 2. pp. 434-449.
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