Publication: Recent studies on the biological action of
parathyroid hormone {PTH)-related peptide (PTHrP)
and PTH/PTHrP receptor in cartilage and bone
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Date
2000
Authors
Amizuka, N. ; Henderson, J. E. ; White, J. H. ; Karaplis, A. C. ; Goltzman, D. ; Sasaki, T. ; Ozawa, H.
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Publisher
F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología
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DOI
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info:eu-repo/semantics/article
Description
Abstract
Mice with a targeted deletion of parathyroid
hormone (PTH)-related peptide (PTHrP) develop a form
of dyschondroplasia resulting from diminished
proliferation and premature maturation of chondrocytes.
Abnormal, heterogeneous populations of chondrocytes at
different stages of differentiation were seen in the
hypertrophic zone of the mutant growth plate. Although
the homozygous null animals die within several hours of
birth, mice heterozygous for PTHrP gene deletion reach
adulthood, at which time they show evidence of
osteopenia. Therefore, PTHrP appears to modulate cell
proliferation and differentiation in both the pre and post
natal period. PTH/PTHrP receptor expression in the
mouse is controlled by two promoters. We recently
found that, while the downstream promoter controls
PTH/PTHrP receptor gene expression in bone and
cartilage, it is differentially regulated in the two tissues.
la,25-dihydroxyvitamin D3 downregulated the activity
of the downstream promoter in osteoblasts, but not in
chondrocytes, both in vivo and .in vitro. Most of the
biological activity of PTHrP is thought to be mediated
by binding of its amino terminus to the PTH/PTHrP
receptor. However, recent evidence suggests that amino
acids 87-107, outside of the amino terminal binding
domain, act as a nucleolar targeting signal. Chondrocytic
cell line, CFK2, transfected with wild-type PTHrP
eDNA showed PTHrP in the nucleoli as well as in the
secretory pathway. Therefore, PTHrP appears to act as a
bifunctional modulator of both chondrocyte proliferation
and differentiation, through signal transduction linked to
the PTHIPTHrP receptor and by its direct action in the
nucleolus.
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Citation
Histology and Histopathology, Vol. 15, n.º 3 (2000)
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