Cell adhesion Cell-matrix glycoconjugates
Cell- matrix glycoconjugates Extracellular matrix (ECM) is composed of several macromolecules bound together in acomplex network. This structure allows cells to adhere, migrate and interact.Hyaluronic acid, a glycosaminoglycan, is a major component of ECM. Hyaluronicacid -binding proteins such as hyaluronic acid receptor LYVE-1, CD44,cartilage link protein CRTL1, Aggrecan, Brevican ( BCAN ) ,Neurocan and Versican, are implicated in cell-matrix interactions and instructurization of the ECM via stabilizing large macromolecular aggregates. They alsoplay an important role in tumor metastasis and cell motility , , , . Aggrecan, Versican, Neurocan, and BCAN are chondroitinsulfate proteoglycans of the ECM. Their interactions with cell surface proteins, as wellas with chemokines such as CCL8, CCL5 and Lymphotactin, playimportant role in cell adhesion . Fibulins are another family of the ECM proteins. Fibulins cross-linkhyaluronan-proteoglycan complexes that play an essential role in supramolecularorganization of cartilaginous and other extracellular matrices . Tenascins are a family of large oligomeric ECM glycoproteins. They all modulatecell-matrix interactions and define the state of matrix attachment that promotes cellmotility . Galectins are a family of beta-galactoside-binding proteins implicated inmodulating cell-cell and cell-matrix interactions. Galectins exist inintracellular and extracellular milieu. In extracellular space, they link withbeta-galactoside containing glycoconjugates of the ECM and cell surface adhesionmolecules that regulate cell adhesion and differentiation , , . ECM remodeling is regulated by a huge number of proteinases and their inhibitors.Alpha-1-microglobulin ( A1M ) is a serine-proteinase inhibitor. It forms complexeswith one or two heavy chains, Inter-alpha (globulin) inhibitors H1, H2 and H3 (ITIH, ITIH2 and ITIH3 ) . The heavy chains arelinked to hyaluronic acid, and this attachment greatly improves ECM stability. A1M exerts an inhibitory activity towards Elastase-2 andPlasmin and it thus suspected of playing a key role in ECM biology . Plasmin takes part in the processing of the matrix metallopreoteinases (MMPs),such as MMP-1. It also cleaves ECM proteins , .Plasmin, MMPs (such as MMP-1, MMP-9 and Stromelysin-1 ),and inhibitors of MMPs (such as TIMP2) directly participate in regulation of celladhesion, migration, and ECM remodeling , .