The Journal of Bone and Joint Surgery (American) 83:S23-S30 (2001)
© 2001 The Journal of Bone and Joint Surgery, Inc.
Growth/Differentiation Factor-5 (GDF-5) and Skeletal Development
Paul Buxton, PhD,
Christopher Edwards, BSc, MBBS, MRCP,
Charles W. Archer, PhD and
Philippa Francis-West, PhD
From Department of Craniofacial Development, King's College
London, London, United Kingdom; Department of Rheumatology, Tan
Tock Seng Hospital, Singapore; and School of Molecular and Medical
Biosciences, University of Wales, Cardiff, United Kingdom
Philippa Francis-West, PhD
Paul Buxton, PhD
Department of Craniofacial Development, King's College London, Guy's
Hospital, St. Thomas Street, London, SE1 9RT, U.K.
Christopher Edwards, BSc, MBBS, MRCP
Department of Rheumatology, Tan Tock Seng Hospital, 11, Jalan Tock
Seng, Singapore
Charles W. Archer, PhD
School of Molecular and Medical Biosciences, University of Wales,
Cardiff, CF1 3YF, U.K.
In support of their research or preparation of this manuscript,
one or more of the authors received grants or outside funding from
the Arthritis and Rheumatism Campaign. None of the authors received
payments or other benefits or a commitment or agreement to provide
such benefits from a commercial entity. No commercial entity paid
or directed, or agreed to pay or direct, any benefits to any research
fund, foundation, educational institution, or other charitable or
nonprofit organization with which the authors are affiliated or
associated.
Background:
Growth/differentiation factor-5 (GDF-5) has been shown to be
essential for normal appendicular skeletal and joint development
in humans and mice. In
brachypod
, a
Gdf-5
gene mouse mutant, the defect is first apparent during early chondrogenesis,
with the cartilage blastema already reduced in size by E12.5. This
defect is associated with changes in the expression of cell surface
molecules.
Methods:
To understand further how GDF-5 controls cartilage formation,
we first mapped the expression of the
Gdf-5
gene during skeletal development (please note that the abbreviation
for the gene is given in italics and the abbreviation for the protein
expressed by the gene is given in capital letters). Subsequently,
we over-expressed GDF-5 in the developing chick embryo using a replication
competent retrovirus, RCAS(BP). We determined its effects on skeletal development
by histological examination and its effects on early growth by autoradiography
of proliferating cells. In addition, we examined the effect of GDF-5
on chondrogenic differentiation using micromass and single cell
suspension cultures of limb mesenchymal cells.
Results:
These studies show that the
Gdf-5
gene is expressed in the early cartilage condensation, the perichondrium,
and the joint interzone. Over-expression of GDF-5 in chick limb
buds, during the condensation stage or later when the skeletal elements
have formed, increased the size of the affected elements. In both
cases, the increase in size was associated with an increase in cell
number and, at later stages, this was correlated with an increase in
S-phase cells.
In vitro
studies showed that GDF-5 could increase cell adhesiveness, and
this may be a mechanism through which GDF-5 initiates condensation
formation.
Conclusion:These studies show that GDF-5 acts at two stages of skeletal
development and by two distinct mechanisms. First, GDF-5 promotes
the initial stages of chondrogenesis by promoting cell adhesion,
which is consistent with the expression of
Gdf-5
in the cartilage condensation. Second, GDF-5 can increase the size
of the skeletal elements by increasing proliferation within the
epiphyseal cartilage adjacent to its expression within the joint
interzone.

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