![]() ![]() Integrins are transmembrane receptors that mediate the attachment between a cell and its surroundings, such as other cells or the extracellular matrix (ECM). At last, there are important molecular components called integrins. In the ECM, especially the basement membrane, the multidomain proteins perlecan, agrin, and COLXVIII are the main proteins to which heparan sulfate attaches. Fibers contain elastin and collagen that include fibrillar (types I, II, III, V, and XI), FACIT (types IX, XII, and XIV), short chain (types VIII and X), basement membrane (type IV), and others (types VI, VII, and XIII) (Figure 1). The ECM is composed of large proteoglycans (PGs) that contain glycosaminoglycan (GAG), hyaluronic acid (HA), fibers, and other molecular components about fibronectin and laminin. ECM components through their action on integrin clustering are involved in cell adhesion, cortical actin cytoskeleton organization, and cell spreading. The ECM of articular cartilage is a unique environment. Cartilaginous ECM is remodeled continuously by a combination of production, degradation by matrix metalloproteinases (MMPs), and inhibition of MMPs activity by tissue inhibitors of MMPs. Because cartilage shows little tendency for self-repair, injuries remain unhealed for years and can lead to further degeneration. Ĭartilage ECM is composed primarily of COLII and large networks of PGs that contain GAG such as HA and CS. Because multicellularity evolved independently in different multicellular lineages, the composition of ECM varies between multicellular structures however, cell adhesion, cell-to-cell communication, and differentiation are common functions of the ECM. In biology, the extracellular matrix (ECM) is the extracellular part of multicellular structure (e.g., organisms, tissues, and biofilms) that typically provides structural and biochemical support to the surrounding cells. In this review, we emphasize the signaling molecule effect and the biomechanics effect of cartilage ECM on chondrogenesis. They orchestrate cell-cell and cell-matrix adhesive interactions from embryonic development to mature tissue function. Integrins are a large family of molecules that are central regulators in multicellular biology. The major signaling pathways that regulate chondrogenesis have been identified as wnt signal, nitric oxide (NO) signal, protein kinase C (PKC), and retinoic acid (RA) signal. Cell signaling through integrins regulates several chondrocyte functions, including differentiation, metabolism, matrix remodeling, responses to mechanical stimulation, and cell survival. Articular cartilage ECM plays a crucial role in regulating chondrocyte metabolism and functions, such as organized cytoskeleton through integrin-mediated signaling via cell-matrix interaction. ![]() Cartilage extracellular matrix (ECM) is composed primarily of the network type II collagen (COLII) and an interlocking mesh of fibrous proteins and proteoglycans (PGs), hyaluronic acid (HA), and chondroitin sulfate (CS). ![]()
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