Abrogation of Cbl-PI3K interaction increases bone formation and osteoblast proliferation

Tracy Brennan, Naga Suresh Adapala, Mary F. Barbe, Vanessa Yingling, Archana Sanjay

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Cbl is an adaptor protein and E3 ligase that plays both positive and negative roles in several signaling pathways that affect various cellular functions. Tyrosine 737 is unique to Cbl and phosphorylated by Src family kinases. Phosphorylated CblY737 creates a binding site for the p85 regulatory subunit of phosphatidylinositol 3 kinase (PI3K) that also plays an important role in the regulation of bone homeostasis. To investigate the role of Cbl-PI3K interaction in bone homeostasis, we examined knock-in mice in which the PI3K binding site on Cbl was ablated due to the substitution of tyrosine 737 to phenylalanine (Cbl YF/YF, YF mice). We previously reported that bone volume in these mice is increased due to decreased osteoclast function (Adapala et al., J Biol Chem 285:36745-36758, 19). Here, we report that YF mice also have increased bone formation and osteoblast numbers. In ex vivo cultures bone marrow-derived YF osteoblasts showed increased Col1A expression and their proliferation was also significantly augmented. Moreover, proliferation of MC3T3-E1 cells was increased after treatment with conditioned medium generated by culturing YF bone marrow stromal cells. Expression of stromal derived factor- 1 (SDF-1) was increased in YF bone marrow stromal cells compared to wild type. Increased immunostaining of SDF- 1 and CXCR4 was observed in YF bone marrow stromal cells compared to wild type. Treatment of YF condition medium with neutralizing anti-SDF-1 and anti-CXCR4 antibodies attenuated MC3T3-E1 cell proliferation. Cumulatively, these results show that abrogation of Cbl-PI3K interaction perturbs bone homeostasis, affecting both osteoclast function and osteoblast proliferation.

Original languageEnglish (US)
Pages (from-to)396-410
Number of pages15
JournalCalcified Tissue International
Volume89
Issue number5
DOIs
StatePublished - Nov 1 2011

Fingerprint

Phosphatidylinositol 3-Kinase
Osteoblasts
Osteogenesis
Mesenchymal Stromal Cells
Bone and Bones
Homeostasis
Osteoclasts
Tyrosine
Binding Sites
Ubiquitin-Protein Ligases
src-Family Kinases
Conditioned Culture Medium
Phenylalanine
Anti-Idiotypic Antibodies
Bone Marrow
Cell Proliferation
Proteins

Keywords

  • Cbl
  • Osteoblast
  • PI3K
  • Proliferation
  • SDF-1

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

Cite this

Abrogation of Cbl-PI3K interaction increases bone formation and osteoblast proliferation. / Brennan, Tracy; Adapala, Naga Suresh; Barbe, Mary F.; Yingling, Vanessa; Sanjay, Archana.

In: Calcified Tissue International, Vol. 89, No. 5, 01.11.2011, p. 396-410.

Research output: Contribution to journalArticle

Brennan, Tracy ; Adapala, Naga Suresh ; Barbe, Mary F. ; Yingling, Vanessa ; Sanjay, Archana. / Abrogation of Cbl-PI3K interaction increases bone formation and osteoblast proliferation. In: Calcified Tissue International. 2011 ; Vol. 89, No. 5. pp. 396-410.
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