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Skeletal overexpression of connective tissue growth factor impairs bone formation and causes osteopenia

Anna Smerdel-Ramoya1, Stefano Zanotti, Lisa Stadmeyer

  • 1Department of Research, Saint Francis Hospital and Medical Center, 114 Woodland Street, Hartford, Connecticut 06105-1299, USA.

Endocrinology
|June 7, 2008
PubMed

Insights

Connective tissue growth factor (CTGF) overexpression in mice led to reduced bone mineral density and impaired bone formation. This suggests CTGF plays a crucial role in maintaining skeletal health and bone development.

Area of Science:

  • Skeletal Biology
  • Molecular Genetics
  • Endocrinology

Background:

  • Connective tissue growth factor (CTGF) is a CCN family protein vital for skeletal development, with null mutations causing neonatal lethality.
  • Understanding CTGF's role in the postnatal skeleton is crucial for bone health research.

Purpose of the Study:

  • To investigate the function of CTGF in postnatal skeletal maintenance.
  • To determine the effects of CTGF overexpression on bone metabolism and signaling pathways.

Main Methods:

  • Generation of transgenic mice overexpressing CTGF under the human osteocalcin promoter.
  • Analysis of bone mineral density, bone histomorphometry, and osteoblast/osteoclast activity.
  • Assessment of gene expression (alkaline phosphatase, osteocalcin) and key signaling pathways (BMP, Wnt, IGF-I).

Main Results:

  • CTGF transgenic mice showed significantly decreased bone mineral density compared to wild-type controls.
  • Histomorphometry revealed reduced trabecular bone volume due to impaired osteoblastic activity (decreased mineral apposition and bone formation rates).
  • Osteoblast and osteoclast numbers and bone resorption remained unaltered; signaling pathways (BMP, Wnt, IGF-I) were reduced.

Conclusions:

  • CTGF overexpression in vivo induces osteopenia, primarily by decreasing bone formation.
  • This effect is potentially mediated by CTGF antagonizing BMP, Wnt, and IGF-I signaling pathways.
  • CTGF is essential for maintaining postnatal skeletal integrity through regulation of bone formation.

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