CYR61

Promoter function of the angiogenic inducer Cyr61gene in transgenic mice: tissue specificity, inducibility during wound healing, and role of the serum response element.

"The cysteine-rich angiogenic protein 61 (Cyr61) is an extracellular matrix-associated, heparin-binding protein that mediates cell adhesion, stimulates cell migration, and enhances growth factor-induced cell proliferation. Cyr61 promotes chondrogenic differentiation and induces neovascularization{LSJL upregulates Cyr61 by 2.504 fold}. A 2-kb fragment of the Cyr61 promoter, which confers growth factor-inducible expression in cultured fibroblasts, is able to drive accurate expression of the reporter gene lacZ in transgenic mice. Transgene expression was observed in the developing placenta and embryonic cardiovascular, skeletal, and central and peripheral nervous systems. The sites of transgene expression are consistent with those observed of the endogenous Cyr61 gene. The transgene expression in the cardiovascular system does not require the serum response element, a promoter sequence essential for transcriptional activation of Cyr61 by serum growth factors in cultured fibroblasts. Because the serum response element contains the CArG box, a sequence element implicated in cardiovascular-specific gene expression, the nonessential nature of this sequence for cardiovascular expression of Cyr61 is unexpected. Cyr61 promoter-driven lacZ expression is inducible in granulation tissue during wound healing, as is synthesis of the endogenous Cyr61 protein, suggesting a role for Cyr61 in wound healing. purified Cyr61 protein promotes the healing of a wounded fibroblast monolayer in culture.we mapped the mouse Cyr61 gene to the distal region of chromosome 3. Cyr61 [has a role] in wound healing through its demonstrated angiogenic activities upon endothelial cells and its chemotactic and growth promoting activities upon fibroblasts."

Differential expression of CCN-family members in primary human bone marrow-derived mesenchymal stem cells during osteogenic, chondrogenic and adipogenic differentiation.

"Primary cultures of human mesenchymal stem cells were obtained from the femoral head of patients undergoing total hip arthroplasty. Differentiation into adipocytes and osteoblasts was done in monolayer culture, differentiation into chondrocytes was induced in high density cell pellet cultures. For either pathway, established differentiation markers and CCN-members were analyzed and the CYR61/CCN1 protein was analyzed. Mesenchymal stem cells expressed CYR61/CCN1, CTGF/CCN2, CTGF-L/WISP2/CCN5 and WISP3/CCN6. The CYR61/CCN1 expression decreased markedly during osteogenic differentiation, adipogenic differentiation and chondrogenic differentiation{interesting that it would increase during LSJL}. WISP2/CCN5 RNA expression declined during adipogenic differentiation and WISP3/CCN6 RNA expression was markedly reduced in chondrogenic differentiation.  CYR61/CCN1 [plays a role in the] maintenance of the stem cell phenotype."

Cyr61, product of a growth factor-inducible immediate-early gene, regulates chondrogenesis in mouse limb bud mesenchymal cells.

"Cyr61 is a secreted, heparin-binding protein (379 amino acids with 38 conserved cysteines) that promotes cell adhesion, migration, and proliferation. The expression pattern of the cyr61 gene during embryogenesis is tissue specific and temporally regulated. cyr61 is transiently expressed in mesenchymal cells of both mesodermal and neuroectodermal origins undergoing chondrogenesis. Cyr61 protein promotes chondrogenesis in micromass cultures of limb bud mesenchymal cells in vitro and is likely to play a similar role in vivo based on the following observations: (1) Cyr61 is present in the embryonic limb mesenchyme during chondrogenesis in vivo and in vitro; (2) purified recombinant Cyr61 protein added exogenously to micromass cultures promotes chondrogenesis as judged by precocious expression of type II collagen, increased [35S]sulfate incorporation, and larger Alcian blue-staining cartilage nodules; (3) Cyr61 enhances cell-cell aggregation, an initial step in chondrogenesis, and promotes chondrogenic differentiation in cultures plated at subthreshold cell densities that are otherwise unable to support differentiation; and (4) neutralization of the endogenous Cyr61 with specific antibodies inhibits chondrogenesis."

Cyr61 can be activated by FGF, PDGF, and TGF-Beta.

Temporal expression of the chondrogenic and angiogenic growth factor CYR61 during fracture repair.

"We employed differential display and compared messenger RNA (mRNA) populations isolated from postfracture (PF) day 5 calluses to those of intact rat femurs. One such gene in which expression was up-regulated at PF day 5 is identified as CYR61, a member of the CCN family of secreted regulatory proteins. CYR61 is a growth factor that stimulates chondrogenesis and angiogenesis. We show that its mRNA expression during fracture repair is regulated temporally, with elevated levels seen as early as PF day 3 and day 5, rising dramatically at PF day 7 and day 10, and finally declining at PF day 14 and day 21. At the highest peak of expression (PF day 7 and day 10, which correlates with chondrogenesis), CYR61 mRNA levels are approximately 10-fold higher than those detected in intact femurs. Similarly, high protein levels are detected throughout the reparative phase of the callus, particularly in fibrous tissue and periosteum, and in proliferating chondrocytes, osteoblasts, and immature osteocytes. The secreted form of CYR61 also was detected within the newly made osteoid. No labeling was detected in hypertrophic chondrocytes or in mature cortical osteocytes."

"we directly compared the mRNA populations isolated from PF day 5 calluses to those of intact femurs (included bone marrow and articular and normal growth plate cartilage) using differential display. Presently, we have identified over a dozen differentially expressed genes, some known (osteopontin{upregulated by LSJL}, bone sialoprotein{up in LSJL}, integrin-α6, major histocompatibility complex (MHC) class II antigen, phosphoglucomutase, fibronectin, versican, vimentin, hypoxia-inducible factor 1α, sec63, SM-20, EET-1, and calpain), and some novel (FxC1{down in LSJL} and FxC2)."

"CYR61 expression is activated by basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), and transforming growth factor β (TGF-β)."

NOV (CCN3) regulation in the growth plate and CCN family member expression in cartilage neoplasia.

"In embryonic murine growth plates, NOV{up in LSJL} was expressed in pre-hypertrophic and early hypertrophic chondrocytes. PTHrP treatment (which inhibits terminal differentiation) decreased NOV expression in murine femurs maintained in organ culture, and decreased the activity of a NOV reporter construct in vitro. Expression of the CCN family members NOV, CTGF, CYR61, and WISP-1 was examined in 15 chondrosarcomas of various grades and in three enchondromas. Expression of all of the family members was lower in the higher-grade tumours."

"The level of expression of NOV decreases in higher-grade, less-differentiated cartilage lesions."