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CRMP4 Inhibits Bone Formation by Negatively Regulating BMP and RhoA Signaling

Basem M Abdallah1,2,3, Florence Figeac1, Kenneth H Larsen1

  • 1Molecular Endocrinology Laboratory (KMEB), Department of Endocrinology, Odense University Hospital & University of Southern Denmark, Odense, Denmark.

Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research
|December 27, 2016
PubMed

Insights

Collapsing response mediator protein-4 (CRMP4) negatively regulates bone formation. CRMP4 deficiency in mice significantly increases bone mass and osteoblast differentiation by enhancing BMP2 signaling.

Area of Science:

  • Cell Biology
  • Skeletal Biology
  • Molecular Biology

Background:

  • Bone marrow stromal stem cells (mBMSCs) differentiate into osteoblasts, a process crucial for bone formation.
  • The molecular mechanisms regulating osteoblast differentiation are complex and not fully understood.
  • Collapsing response mediator proteins (CRMPs) are involved in neuronal development, but their role in bone biology is largely unexplored.

Purpose of the Study:

  • To investigate the role of CRMP4, a neuroprotein, in osteoblast differentiation and bone formation.
  • To determine if CRMP4 acts as a regulator of skeletal stem cell differentiation.

Main Methods:

  • CRMP4 expression analysis in mouse and human bone tissues.
  • In vitro gain-of-function and loss-of-function studies using murine stromal cells.
  • Analysis of bone mass, mineral apposition rate, and bone formation rate in CRMP4-deficient mice (Crmp4-/-).
  • Investigation of BMP2 signaling, RhoA/FAK signaling, and cell proliferation pathways in CRMP4-deficient osteoblasts.

Main Results:

  • CRMP4 is expressed in mBMSCs and osteoprogenitors in mouse and human bones.
  • CRMP4 inhibits osteoblast differentiation in vitro.
  • Crmp4-/- mice exhibit a 40% increase in bone mass, elevated mineral apposition rate, and bone formation rate.
  • CRMP4 deficiency enhances BMP2 signaling and BMP2-induced osteoblast differentiation.
  • CRMP4 deficiency leads to increased RhoA/FAK signaling, cytoskeletal changes, and enhanced osteoblast proliferation via modulation of p27Kip1 and cyclin D1.

Conclusions:

  • CRMP4 is identified as a novel noncanonical osteogenic factor.
  • CRMP4 acts as a negative regulator of osteoblast differentiation and bone formation.
  • Targeting CRMP4 may offer therapeutic potential for bone diseases characterized by low bone mass.
Keywords:
BONE REMODELINGCRMP4DPYSL3OSTEOBLASTOSTEOPOROSIS

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