ARTHRITIS & RHEUMATISM
Vol. 44, No. 10, October 2001, pp 2296–2310
© 2001, American College of Rheumatology
Published by Wiley-Liss, Inc.
Synergistic Induction of Matrix Metalloproteinase 1 by
Interleukin-1 and Oncostatin M in Human Chondrocytes
Involves Signal Transducer and Activator of
Transcription and Activator Protein 1 Transcription Factors
via a Novel Mechanism
J. B. Catterall,
1
S. Carre `re,
1
P. J. T. Koshy,
1
B. A. Degnan,
1
W. D. Shingleton,
1
C. E. Brinckerhoff,
2
J. Rutter,
2
T. E. Cawston,
1
and A. D. Rowan
1
Objective. To investigate the mechanism of
interleukin-1 (IL-1) and oncostatin M (OSM) syner-
gistic regulation of matrix metalloproteinase 1
(MMP-1) in human chondrocytes.
Methods. Using an immortalized human chon-
drocyte cell line (T/C28a4), we investigated regulation of
the MMP-1 gene. Northern blotting and flow cytometric
analysis were used to assess changes in receptor,
MMP-1, and c-fos expression. Transient transfections
using MMP-1 promoter/luciferase constructs, electro-
phoretic mobility shift assay, and site-directed mu-
tagenesis were used to investigate MMP-1 promoter
activation.
Results. We found no alteration in the expression
of receptors used by these cytokines after stimulation
with IL-1/OSM. Using MMP-1 promoter/luciferase
reporter constructs, we found that the proximal (517/
63) region of the MMP-1 promoter was sufficient to
support a synergistic activation. A role for activated
signal transducers and activators of transcription
(STAT-3) was demonstrated, although no binding of
STAT-3 to the MMP-1 promoter was found. However,
constitutive binding of activator protein 1 (AP-1) was
detected, and changes in c-fos expression could modu-
late promoter activity.
Conclusion. Since no changes in receptor expres-
sion were observed, receptor modulation cannot account
for the IL-1/OSM synergy observed. Instead, the inter-
play of various intracellular signaling pathways is a
more likely explanation. STAT activation is required,
but STAT proteins do not interact directly with the
MMP-1 promoter. We propose that activated STATs
stimulate c-fos expression, and changes in expression of
the AP-1 components regulate MMP-1 expression. We
highlight a new mechanism for MMP-1 regulation in
human chondrocytes that could provide potential new
therapeutic targets.
Rheumatoid arthritis (RA) is a disease in which
the end stage is characterized by loss of joint function
due to degradation of articular cartilage. Proteoglycans
and collagen are the 2 major components of this extra-
cellular matrix; they provide both the resistance to
compressive forces and its tensile strength. A family of
closely related enzymes, the matrix metalloproteinases
(MMPs), which collectively can degrade all the compo-
nents of the extracellular matrix of articular cartilage,
have been strongly implicated in the disease process (1).
Recent evidence now suggests that proteoglycan turn-
over is mediated by ADAM-TS4 and/or ADAM-TS5
(2,3). However, proteoglycan can be replaced relatively
rapidly once the proinflammatory cytokine stimulus,
such as interleukin-1 (IL-1), has been removed (4). In
marked contrast, collagen is released much less readily,
but when degradation of collagen does occur, the struc-
Supported by the Arthritis Research Campaign.
1
J. B. Catterall, PhD, S. Carre `re, PhD, P. J. T. Koshy, PhD,
B. A. Degnan, PhD, W. D. Shingleton, PhD, T. E. Cawston, PhD,
A. D. Rowan, PhD: University of Newcastle upon Tyne, Newcastle
upon Tyne, UK;
2
C. E. Brinckerhoff, PhD, J. Rutter, PhD: Dartmouth
Medical School, Hanover, New Hampshire.
Address correspondence and reprint requests to J. B. Catter-
all, PhD, Department of Rheumatology, School of Clinical Medical
Sciences, Cookson Building, The Medical School, University of New-
castle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH,
UK. E-mail: J.B.Catterall@ncl.ac.uk
Submitted for publication November 10, 2000; accepted in
revised form May 24, 2001.
2296