第十章 细胞外基质及其及细胞的相互作用.ppt

第二节、细胞外基质的特化结构 基底膜：细胞外基质的特化结构形式，分布于上皮细胞和内皮细胞的基底部，将细胞与结缔组织隔离。 基底膜组成： 第三节 细胞外基质与细胞间的相互作用 机体组织由细胞与细胞外基质共同构成，一方面细胞通过控制基质成分的合成和降解决定细胞外基质组成，另一方面细胞外基质对细胞生命活动有重要影响。 基质对细胞生物学行为影响：形态结构、生存、死亡（失巢凋亡）、增殖与分化 细胞对细胞外基质的影响：由细胞所在组织细胞分泌，由细胞控制基质成分的降解 失巢凋亡 癌细胞向远端转移 * The connective tissue underlying an epithelial cell sheet. It consists largely of extracellular matrix that is secreted by the fibroblasts Scanning electron micrograph of fibroblasts in connective tissue. The tissue is from the cornea of a rat. The extracellular matrix surrounding the fibroblasts is composed largely of collagen fibrils (there are no elastic fibers in the cornea). The glycoproteins, glycosaminoglycans, and proteoglycans, which normally form a hydrated gel filling the interstices of the fibrous network, have been removed by enzyme and acid treatment. * * An aggrecan aggregate from fetal bovine cartilage. (A) Electron micrograph of an aggrecan aggregate shadowed with platinum. Many free aggrecan molecules are also seen. (B) Schematic drawing of the giant aggrecan aggregate shown in (A). It consists of about 100 aggrecan monomers (each like the one shown in Figure 19-37) noncovalently bound to a single hyaluronan chain through two link proteins that bind to both the core protein of the proteoglycan and to the hyaluronan chain, thereby stabilizing the aggregate; the link proteins are members of the hyaladherin family of hyaluronan-binding proteins discussed previously. The molecular weight of such a complex can be 108 or more, and it occupies a volume equivalent to that of a bacterium, which is about 2 x 10-12 cm 3. * The linkage between a GAG chain and its core protein in a proteoglycan molecule. A specific link tetrasaccharide is first assembled on a serine residue. In most cases it is not clear how the serine residue is selected, but it seems to be a specific local conformation of the polypeptide chain, rather than a specific linear sequence of amino acids, that is recognized. The rest of the GAG chain, cons