CTGF, also known as CCN2 or connective tissue growth factor, is a matricellular protein of the CCN family of extracellular matrix-associated heparin-binding proteins (see also CCN intercellular signaling protein). CTGF plays important roles in various biological processes, including cell adhesion, cell migration, cell growth, angiogenesis, skeletal development, and tissue wound repair, and is critically involved in fibrotic disease and several forms of cancer.
Structure and binding partners
Members of the CCN protein family, including CTGF, are structurally characterized by having four conserved,
cysteine-rich domains. These domains are, from N- to C-termini, the insulin-like growth factor binding protein (IGFBP) domain, the von Willebrand type C repeats (vWC) domain, the thrombospondin type 1 repeat (TSR) domain, and a C-terminal domain (CT) with a
cysteine knot motif. CTGF exerts its functions by binding to various cell surface receptors in a context-dependent manner, including integrin receptors,
cell surface heparan sulfate proteoglycans (HSPGs),
LRPs,
and TrkA.
In addition, CTGF also binds growth factors and extracellular matrix proteins. The N-terminal half of CTGF interacts with
aggrecan,
the TSR domain interacts with
VEGF and, the CT domain interacts with members of the TGF-β superfamily,
fibronectin,
perlecan, fibulin-1, slit, and
.
Role in development
Knockout mice with the Ctgf gene disrupted die at birth due to respiratory stress as a result of severe
chondrodysplasia.
Ctgf-null mice also show defects in angiogenesis, with impaired interaction between endothelial cells and pericytes and collagen IV deficiency in the endothelial basement membrane.
CTGF is also important for pancreatic beta cell development
and is critical for normal
ovarian follicle development and
ovulation.
Clinical significance
CTGF is associated with
wound healing and virtually all
fibrotic pathology.
It is thought that CTGF can cooperate with TGF-β to induce sustained
fibrosis and to exacerbate extracellular matrix production in association with other fibrosis-inducing conditions.
Overexpression of CTGF in fibroblasts promotes fibrosis in the dermis, kidney, and lung,
and deletion of Ctgf in fibroblasts and smooth muscle cells greatly reduces
bleomycin-induced skin fibrosis.
In addition to fibrosis, aberrant CTGF expression is also associated with many types of malignancies, diabetic nephropathy and retinopathy, arthritis, and cardiovascular diseases. Several clinical trials are now ongoing that investigate the therapeutic value of targeting CTGF in fibrosis, diabetic nephropathy, and pancreatic cancer.
CTGF (CCN2) has recently been implicated in mood disorders, notably in the postpartum period; these effects may be mediated by its effects on myelination
See also
-
Ctgf/hcs24 CAESAR
-
CYR61 (CCN1)
External links