Perlecan is a component of cartilage matrix and promotes chondrocyte attachment

Abstract

Aggrecan, a chondroitin/keratan sulfate-containing proteoglycan, is a major component of cartilaginous tissues. Immunolocalization studies, using antibodies directed to perlecan, a heparan sulfate proteoglycan first detected in basement membranes, and laminin (another major component of basement membranes), indicate that perlecan and laminin are also present in the matrices of hyaline cartilage in the nasal septum, the articular surface of the bone and the growth plate of the developing bone. Consequently, we used antibodies to both aggrecan and perlecan to characterize their synthesis and secretion by primary cultures of chondrocytes derived from the rat chondrosarcoma. Chondrocytes were pulsed for 20 minutes with [35S]methionine and then chased for up to six hours. The radiolabeled perlecan and aggrecan were immunoprecipitated and analyzed by SDS-PAGE. The results show that chondrocytes synthesize precursor proteins to both proteoglycans, but that only the aggrecan precursor protein is secreted as a proteoglycan. Perlecan was also secreted but with less posttranslational modifications than aggrecan. Northern blot analyses of the RNAs from immortalized rat chondrocytes indicated that the major mRNA encoding for perlecan was approximately 13 kb in length, similar in size to that expressed by other cell types, which synthesize 400 kDa core protein perlecan. Analyses of the proteoglycan fractions from the extracts of bovine articular surface indicated that perlecan in this tissue contains both chondroitin and heparan sulfate side-chains. Purified perlecan and laminin were found to promote attachment of immortalized rat chondrocytes in vitro. These studies indicated that perlecan, once thought to be a unique component of the basement membranes, is more widely distributed and is an important component of the cartilage matrix, where it may provide for cell adhesion to the matrix.

Trachea Mechanics for Tissue Engineering Design

“…Tracheal cartilage exhibits particularly strong and uniform staining for Safrinin O, indicating high proteoglycan content . The predominant proteoglycan in hyaline cartilage is aggregan, yet it is the unique combination and organization of a variety of proteoglycans that engenders cartilage compressive properties; members of all classes of small leucine-rich proteoglycans (SLRPs) are found in cartilage, including decorin, biglycan, fibromodulin, lumican, epiphycan, and perlecan …”

“…23 The predominant proteoglycan in hyaline cartilage is aggregan, yet it is the unique combination and organization of a variety of proteoglycans that engenders cartilage compressive properties; 25 members of all classes of small leucine-rich proteoglycans (SLRPs) are found in cartilage, including decorin, 26 biglycan, 27 fibromodulin, 28 lumican, 29 epiphycan, 30 and perlecan. 31 Cartilage is typically modeled as a biphasic material to account for the behavior and interaction of the solid matrix phase and the interstitial fluid phase. 32 Its highly negatively charged proteoglycan content enables fluid retention and regulates permeability of the tissue.…”

Application of Alginate Hydrogels for Next-Generation Articular Cartilage Regeneration

“…Other collagens include smaller amounts of type-VI [23,[30][31][32][33]37], -IX [20,23,28,[30][31][32][33][34][35][36][37], -XI [20,23,28,[30][31][32][33][34][35][36][37], and -XIV collagen [30][31][32]37], and some type-I/-X collagen [38], which play important roles in the formation and stability of fibrils in the mature articular cartilage [39]. Compared with the territorial matrix, a variety of matrix molecules, such as aggrecan monomers and small aggregates [40,41], type-VI [42,43] and -IX collagen [44,45], hyaluronan [41,46], biglycan [47], and perlecan [48], can be found either exclusively or at higher concentration in the pericellular matrix. Interactions between the molecular constituents of the ECM contribute to the distinct macrostructure of the ECM.…”

Heparan Sulfate: A Complex Polymer Charged with Biological Activity

“…244 In addition, perlecan protein core binds several extracellular matrix molecules 245 and acts as either an adhesive or a counter-adhesive molecule. 154,[246][247][248] Angiogenesis is one of the most important events in tumor progression 234,249,250 and is greatly influenced by cell-matrix interactions taking place at the surface of endothelial cells and at tumor-matrix boundaries. 251 Recently, the C-terminal domain V of perlecan was shown to be a potent inhibitor of angiogenesis.…”

“…Blocking endogenous production of perlecan suppresses autocrine and paracrine functions of FGF-2 and impairs tumor growth and invasion. − Perlecan also binds to FGF-7 , and is required for functional activation of the FGF-7 receptor . In addition, perlecan protein core binds several extracellular matrix molecules and acts as either an adhesive or a counter-adhesive molecule. ,− Angiogenesis is one of the most important events in tumor progression ,, and is greatly influenced by cell−matrix interactions taking place at the surface of endothelial cells and at tumor−matrix boundaries . Recently, the C-terminal domain V of perlecan was shown to be a potent inhibitor of angiogenesis .…”