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INTRODUCTION
The Orthopaedics Department at Beth Israel
Deaconess Medical Center, as a part of CareGroup, has begun a new collaboration
with the New England Baptist Bone and Joint Institute Basic Science Laboratory.
This laboratory is located at the Harvard Institutes of Medicine, Harvard
Medical School. It occupies over 8,000 square feet of research space that
includes a Genomics Core (that serves as the Beth Israel Deaconess Medical
Center Genomics Center) and a Molecular Pathology Core. There are nine
principal investigators who are working with a team of thirty-three post-doctoral
fellows, graduate students, and laboratory technicians investigating more
than two dozen studies. These projects are funded by over $5 million from
the NIH, the Arthritis Foundation and also from private industry support.
One of those projects, the NIDDK Biotechnology Center Grant, is one of
only ten awarded in the country by the National Institutes of Health.
PRINCIPAL INVESTIGATORS: CURRENT PROJECTS
Steven R. Goldring, M. D. is the Director of
Research for the laboratory. He is a Professor of Medicine at Harvard
Medical School and is the Chief of Rheumatology at the Beth Israel Deaconess
Medical Center and the New England Baptist Hospital.
Cellular Responses to Inorganic Particulates
The aims of this project are to: (1) test the
hypothesis that particle surface chemistry and crystal structure are critical
determinants of the pattern and magnitude of cell responses to inorganic
particulate wear debris associated with total joint replacements, (2)
test the hypothesis that lipopolysaccharide (LPS) "contamination"
accounts for a component of particleinduced cell responses, and (3) test
the hypothesis that the molecular pathways by which particles regulate
the IL-1 β and TNF- α genes differ and that particle-mediated
effects involve LPS-dependent and independent signal transduction systems.
These experimental approaches will permit the dissection of the molecular
mechanisms and signaling pathways by which foreign particulate materials
modulate cell responses and will provide important insights into the factors
responsible for the adverse cellular and tissue reaction to particulate
implant wear debris.
Calcitonin Receptor Gene Expression
The aims of this project are to: (1) characterize
the structural and functional properties of the osteoclast calcitonin
receptor, (2) identify the phenotypic relationship between bone resorbing
cells in physiological and pathological remodeling, (3) determine if there
are osteoclast “subtypes” without calcitonin receptors and if
so, what controls their development, and (4) determine the cellular and
molecular mechanisms regulating calcitonin receptor gene during osteoclast
differentiation.
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Accessory Cell Activation in
the Immune Response The major goals of this project are elucidation of
the mechanism for immediate early gene induction in activated monocytes
using the IL-1 gene as a model.
IL-1 Receptor Mediated Signal Transduction The
major goals of this project are to understand the mechanism of IL-1 receptor
signal transduction, focusing on both ligand-receptor interactions and
cytoplasmic domain recruitment of signaling molecules, focusing especially
on the mechanism of phosphatidylinositol 3-kinase activation of NF- kB.
Osteoclastogenesis and RANK signaling to NF-kB
via TRAF6
Considerable evidence in animal models and
in humans indicates that bone loss in periodontitis is produced by osteoclasts.
The origin of osteoclasts and the factors responsible for their recruitment,
differentiation, and activation are not well defined. A newly described,
required factor for the differentiation and activation of osteoclasts
is Receptor and Activator of NF-kB Ligand (RANKL) which mediates its effects
via a specific cell surface receptor, Receptor and Activator of NF-kB
(RANK). This receptor is a member of the TNF receptor family, and is expressed
on osteoclasts and osteoclast precursors. With RANKL binding to its receptor,
a cascade of signal transduction events occurs to ultimately culminate
in the activation of transcription factors, which effect expression of
target genes important for osteoclast differentiation. NF-kB is one such
transcription factor that is known to be activated and required for osteoclastogenesis.
The signaling pathway from receptor to activation of NF-kB is not understood.
The intracellular domain of RANK is linked to downstream signaling molecules
by adapter proteins of the TNF Receptor Associated Factor (TRAF) family,
which have no intrinsic catalytic properties, but are able to associate
with molecules that do. One member, TRAF6, associates with RANK, and links
it to a MAP3 kinase named TGFβ Activated Kinase 1 (TAK1), which is
involved in NF-kB activation. The studies outlined in this proposal will
examine how TRAF6 functions to activate TAK1 and induce NF-kB activation
and how these events lead to osteoclast differentiation and activation.
A more detailed understanding of the basic regulation of osteoclastogenesis
may permit development of potent novel therapeutics for treating periodontal
disease and other inflammatory disorders associated with bone loss.
Regulation of the Murine Calcitonin Receptor
Gene
The aims of this project are to: (1) clone
and characterize the murine CTR gene and identify the transcription start
site(s) in osteoclasts and other mCTR-expressing cell-types, (2) define
the specific and potentially unique regulatory sequences responsible for
expression of mCTR in osteoclasts and other mCTR-expressing cells and
tissues and identify the putative trans-acting transcription factors that
bind to these sequences, (3) investigate the developmental regulation
of the mCTR gene, and (4) determine the effect of targeted disruption
of the mCTR gene on osteoclasts and other mCTR-expressing tissues, and
on mouse development.
Signaling Pathways in Chondrocyte-Specific Gene
Expression
The major goal of this work is to define the
cellular and molecular mechanisms by which catabolic cytokines suppress
differentiated phenotype in chondrocytes. The hypothesis is that cytokine-
and dedifferentiation-induced downregulation of chondrocyte phenotype
occurs by both distinct and convergent signaling pathways.
Regulation of Matrix Gene Expression in Human Chondrocytes
The major goals of this project are to: (1)
determine factors that maintain and enhance chondrocyte phenotype in immortalized
human chondrocyte culture models in vitro, (2) identify molecular mechanisms
involved in induction and maintenance of differentiated chondrocyte phenotype
by direct analysis of regulatory sequences of the cartilage-specific type
II collagen gene (COL2A1), and (3) examine factors influencing cartilage
formation in vivo.
Pathogenesis of Bone Erosion in Rheumatoid Arthritis
Considerable evidence indicates that focal
bone erosions in rheumatoid arthritis are produced by cells expressing
phenotypic features of osteoclasts. The origin of these osteoclastlike
cells and the factors responsible for their recruitment, differentiation,
and activation are not well defined. An essential factor for the differentiation
and activation of osteoclasts is receptor-activator of NF-kB ligand (RANKL).
The balance between RANKL and its decoy receptor, osteoprotegerin, an
inhibitor of RANKL activity, is a critical determinant of osteoclast differentiation
in normal bone remodeling. The major goals of this project are to test
the hypothesis that cells present in rheumatoid arthritis synovium at
sites of bone invasion provide a source of RANKL that contributes to pathologic
focal osteoclast mediated bone resorption. An increased understanding
of the pathogenesis of bone erosion in rheumatoid arthritis will lead
to new therapeutic strategies for preventing the disabling bone destruction
in this disease.
In vivo MRI of Cartilage Glycosaminoglycan Content
The major goal of this project is to develop
a technique for monitoring articular cartilage glycosaminoglycan content
in vivo. The specific aims are to: (1) establish a protocol for the delivery
of Gd(DTPA)2- to cartilage in vivo, (2) quantify the levels of glycosaminoglycan
in vivo, and (3) validate the interpretation of the in vivo method as
providing a quantitative measure of cartilage glycosaminoglycan content.
Clinical and Non-Invasive Mechanical and Physico-chemical Analysis of
Hip Dysplasia
The specific aims of this project are to:
(1) characterize glycosaminoglycan density in articular cartilage, using
MRI, in acetabular dysplasia. Correlate these MRI findings with clinical
symptoms and conventional radiographic measures as well as load density
profile obtained using CT analysis, and (2) determine if periacetabular
osteotomy is capable of restoring the articular cartilage integrity in
dysplasia hips. If the articular cartilage integrity is restored, does
it correlate with restoration of normal hip joint mechanics and does it
correlate with resolution of symptoms?
MRI of Cartilage Mechanical Properties
An MRI technique to image the glycosaminoglycan
content of cartilage has been demonstrated that can serve as a surrogate
for biochemical and histological evaluation of the tissue glycosaminoglycan.
The main challenge being addressed by this proposal is to obtain pilot
data to determine whether this MRI technique can be used to predict the
mechanical properties of the tissue.
Function of ELF-1 and a Novel Ets Factor NERF
in B Cells
The major goals of this project are to determine
the role of ELF-1 and NERF in regulation of blk gene expression and to
determine effect of targeted disruption of the NERF gene on B cell development
and blk gene expression.
Role of New Ets Factor, ESE1, in Epithelial Cells
The major goals of this project are to determine
the biological role of a novel epithelial cell-specific transcription
factor, ESE-1, during epithelial cell differentiation and to explore its
role as a down-stream target of cytokines involved in the pathogenesis
of inflammatory disorders such as rheumatoid arthritis.
NIDDK Biotechnology Center
The goal of the NIDDK Biotechnology Center
is to build a comprehensive integrated microarray facility that will allow
researchers to create and analyze customized and commercial expression
arrays as tools to gain new insights into disease pathogenesis and mechanisms.
Furthermore, this comprehensive integrated microarray facility will also
permit the characterization of the functional and regulatory pathways
of disease related genes.
The Role of the Novel Prostate-Specific Transcription Factor, PDEF, on
Prostate Cancer
The major goal of this project is to determine
the role of PDEF, a member of the Ets transcription factor/oncogene family,
in prostate cancer. Due to direct implication of Ets factors in human
cancers, PDEF is expected to play a role in the proliferation and metastatic
spread of prostate cancer.
The Role of the Ets Factor NERF in Vasculogenesis
Vasculogenesis is the formation of blood vessels
and a primary vascular network in the developing embryo. Several growth
factors including vascular endothelial growth factor (VEGF), fibroblast
growth factor (FGF), Angiopoeitin, and their receptors Flk-1, Flt-1, Tie1,
and Tie2 have been identified as being important mediators of these events.
The approach to determining the factors which are critical for blood vessel
development and endothelial cell differentiation is to identify the transcription
factors which regulate vascular-specific genes. The Ets genes are a family
of transcription factors that regulate developmental processes and cellular
differentiation. Conserved Ets sites have been identified in the promoters
of the Tie1 and Tie2 genes which are necessary for vascular directed expression
of these genes. In addition, a novel human Ets factor, NERF which is expressed
in endothelial cells has been characterized. This Ets factor is expressed
as at least three isoforms, of which the NERF2 isoform is a strong transactivator
of the Tie1 and Tie2 genes. The NERF1 isoforms can down-regulate vascular
specific genes, and their overexpression leads to the impaired formation
of vascular tubes and channels. The hypothesis for these studies is that
selected members of the Ets factor family and in particular, NERF, are
critical regulators of vascular development and endothelial function.
The Role of ESE-1 in Vascular Inflammation
Inflammation, a hallmark of atherosclerosis
and other vascular diseases is characterized by the activation of several
genes including cytokines, adhesion molecules, cyclooxygenases, and nitric
oxide synthase. Our approach to unraveling the molecular mechanisms that
mediate early inflammatory responses is to identify the transcription
factors that mediate these responses. The NF-kB family of transcription
factors are known to be critical mediators of these events. We have determined
that a novel Ets transcription factor ESE-1, is induced in response to
interleukin-1(IL-1), tumor necrosis factor(TNF-α), and endotoxin
in vascular smooth muscle cells, endothelial cells and monocytes. This
induction is at least in part mediated by NF-kappa B. We have identified
the inducible form of nitric oxide synthase (NOS-2) as a target for ESE-1.
Induction of NOS-2 and consequent production of nitric oxide (NO), has
a wide variety of cellular effects depending on the cell type and the
amount of NO produced. The hypothesis for these studies is that the Ets
factor ESE-1 is a transcriptional mediator of vascular inflammation. The
goal of this study is to examine the role of ESE-1 as a transcriptional
regulator of vascular inflammation and NOS-2 gene regulation. The results
of these studies should provide new insights into the molecular mechanisms
involved in regulating vascular inflammation and provide potential new
therapeutic avenues for treatment of vascular diseases such as atherosclerosis,
restenosis, and the vasculopathy. The Role of Angiopoietin-1 in Rheumatoid
Arthritis Angiogenesis is a critical component of the inflammation associated
with rheumatoid arthritis (RA). Several angiogenic growth factors including
vascular endothelial growth factor (VEGF) and basic fibroblast growth
factor (bFGF) have been identified within the rheumatoid synovium, all
of which promote the early steps of angiogenesis. Attempts to block angiogenesis
by inhibiting these factors in animal models of inflammatory arthritis
have resulted in partial reductions in overall inflammation, pannus formation,
and the degree of angiogenesis. Recently, a novel angiogenic factor, Angiopoietin-1
(Ang-1), was identified that has the unique property of facilitating the
later stages of angiogenesis. Our preliminary results demonstrate that
Ang-1 is expressed in synovial fibroblasts derived from patients with
RA. Furthermore, proinflammatory cytokines can markedly upregulate the
expression of Ang-1 in these cells and induce Ang-1 expression in other
cell types found in the rheumatoid joint including monocytes and chondrocytes.
The expression of Ang-1 by synovial fibroblasts may also enhance endothelial
cell migration to the growing pannus. The hypothesis of this proposal
is that Ang-1 is one of the critical factors required for mediating the
angiogenic response in rheumatoid arthritis. The goals of these studies
are to define the role of Ang-1 in promoting the angiogenic component
of inflammatory arthritis, to further define the role of NERF2 as a transcriptional
mediator of Ang-1, and to examine the therapeutic potential of blocking
Ang-1 during the development of inflammatory arthritis.
is the Director of Research for the laboratory. He is a Professor of Medicine
at Harvard Medical School and is the Chief of Rheumatology at the Beth
Israel Deaconess Medical Center and the New England Baptist Hospital.
Address correspondence to:
Steven R. Goldring, MD
Harvard Institutes of Medicine,
Room 244
4 Blackfan Circle
Boston, MA 02115
Note: No References for this Manuscript
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