Erickson Michael, Stern Robert
Department of Basic Biomedical Sciences, Touro College of Osteopathic Medicine, 230 West-125th Street, New York, NY 10027, USA.
Biochem Res Int. 2012;2012:893947. doi: 10.1155/2012/893947. Epub 2011 Dec 18.
Hyaluronan is a matrix polymer prominent in tissues undergoing rapid growth, development, and repair, in embryology and during malignant progression. It reaches 10(7) Daltons in size but also exists in fragmented forms with size-specific actions. It has intracellular forms whose functions are less well known. Hyaluronan occurs in all vertebrate tissues with 50% present in skin. Hyaluronan provides a scaffold on which sulfated proteoglycans and matrix proteins are organized. These supramolecular structures are able to entrap water and ions to provide tissues with hydration and turgor. Hyaluronan is recognized by membrane receptors that trigger intracellular signaling pathways regulating proliferation, migration, and differentiation. Cell responses are often dependent on polymer size. Catabolic turnover occurs by hyaluronidases and by free radicals, though proportions between these have not been determined. New aspects of hyaluronan biology have recently become realized: involvement in autophagy, in the pathology of diabetes., the ability to modulate immune responses through effects on T regulatory cells and, in its fragmented forms, by being able to engage several toll-like receptors. It is also apparent that hyaluronan synthases and hyaluronidases are regulated at many more levels than previously realized, and that the several hyaluronidases have functions in addition to their enzymatic activities.
透明质酸是一种基质聚合物，在胚胎学以及恶性进展过程中经历快速生长、发育和修复的组织中尤为突出。其大小可达10^7道尔顿，但也以具有特定大小作用的片段形式存在。它有细胞内形式，但其功能尚不太清楚。透明质酸存在于所有脊椎动物组织中，其中50%存在于皮肤中。透明质酸提供了一个支架，硫酸化蛋白聚糖和基质蛋白在其上有序排列。这些超分子结构能够截留水和离子，为组织提供水合作用和膨胀性。透明质酸可被膜受体识别，这些受体触发调节增殖、迁移和分化的细胞内信号通路。细胞反应通常取决于聚合物大小。分解代谢通过透明质酸酶和自由基进行，不过两者之间的比例尚未确定。透明质酸生物学的新方面最近已被认识到：参与自噬、糖尿病病理过程、通过对调节性T细胞的影响调节免疫反应的能力，以及以其片段形式能够激活几种Toll样受体。同样明显的是，透明质酸合酶和透明质酸酶在比以前认识到的更多水平上受到调节，并且几种透明质酸酶除了其酶活性外还有其他功能。
