Somatomedins as regulators of proteoglycan synthesis.
Somatomedins as regulators of proteoglycan synthesis.
复制标题
生长调节素作为蛋白多糖合成的调节剂。
作者：
Z. Nevo
生长抑素对细胞的多型性效应是众所周知的。本文综述了生长激素(SM)作为蛋白多糖(PG)合成调节剂的研究进展。一旦了解了SMS这一作用的机制，就可以作为一个通用的大分子模型来研究SMS对结缔组织基质成分的影响。调节PG产量的因素可分为两类：1.细胞内因素，包括遗传密码、合成酶及其组织、积木物质的利用率、各种细胞营养因子和降解酶。所有这些都决定了基本的生产率。2.细胞外因子，包括腺体分泌的激素和具有调节能力的组织局部因子。激素因素可能会改变PG的产生速率，并产生产物成分的差异，反映出个体发育、生理和/或病理状态的变化。据报道，促前列腺素合成的激素如促甲状腺激素和抑制糖皮质激素可调节PG的合成，而生长抑素(SM)家族似乎在这一调节中起着关键作用。生长抑素是指一种物质与生长激素(生长激素)的关系，以及它在将生长激素信息传递到靶细胞或胞体细胞(如成纤维细胞、软骨细胞、骨细胞等)中的中介作用。SM家族最多包括六个成员：SM-A、SM-B、SM-C、NSILA(不可抑制的胰岛素样活动)I和11，或新术语IGF(胰岛素样生长因子)I和11，以及MSA(增殖刺激活性)。SMS有一些共同的元素，它们的一些特征列在表I中。简而言之，SMS是一组小分子多肽(从4000到8000道尔顿)，其生物活性可以表示为促进生长、胰岛素样和有丝分裂活性。主要通过SM对基质生成率的影响来评估其促生长活性：这是通过刺激不同动物的软骨切片中的硫酸盐掺入来衡量的。SMS的内分泌途径始于下丘脑的分泌物，导致GH从脑下分泌出来。这种生长激素被认为产生了SMS的合成，主要是在肝脏和肾脏，然后通过细胞膜上的特定受体位置对目标细胞进行操作。多年来，PG合成(基质产生)已成为骨框架整体生长过程的指标，血液中SMS水平已成为临床上衡量血清中生长因子含量的合成指标。
The pleiotypic effect of somatomedins on cells is well-known. This review deals with somatomedins (SMs) as regulators of proteoglycan (PG) synthesis. Once the mechanism of this role of SMs is understood, it can be used as a general macromolecular model for studying the effects of SMs on matrix components of connective tissues. The factors regulating PG production rate can be classified into two categories: 1. Intracellular factors which integrate the following: the genetic code, the synthetic enzymes and their organization, the availability of building block substances, various cell nutritional factors, and =-degrading enzymes. All these determine the basic rate of production. 2. Extracellular factors, including hormones secreted from glandular organs and tissuelocal agents with regulation ability. The hormonal factors may alter rates of PG production and generate differences in the product composition, reflecting changes in the individual’s developmental, physiological and/or pathological status. While hormones such as thyroxine which stimulates the rate and glucocorticosteroids which suppress the rate have been reported to regulate PG synthesis, the somatomedin (SM) family seems to play a key role in this regulation. The term somatomedin denotes the relation of a substance to somatotrophin (growth hormone (GH)), and its intermediary (mediator) role in transmitting the message of GH to the target or soma cells (e.g. fibroblasts, chondrocytes, osteocytes, etc.). At most, the SM family includes six members: SM-A, SM-B, SM-C, NSILA (non-suppressible insulinlike activity) I and 11, or in the new terminology IGF (insulin-like growth factor) I and 11, and MSA (multiplication stimulating activity). The SMs share certain common elements, and some of their characteristics are listed in Table I. In brief, the SMs are a group of low molecular weight polypeptides (ranging from 4000 to 8000 daltons) whose biological activity can be expressed as growth-promoting , insulin-like and mitogenic. The growth-promoting activity is assessed mainly by the effect of SM on the rate of matrix production: this is measured as the stimulation of sulfate incorporation into cartilage slices of various animals. The endocrine route of SMs begins with the hypothalamic secretions which cause the release of GH from the pituitary. This GH is believed to generate the synthesis of SMs, mainly in the liver and kidney, which then operate on their target cells via specific receptor sites on the cell membranes. PG synthesis (matrix production) has become over the years the indicator of the overall growth process of the bony framework and the level of SMs in blood has come to serve as the clinical anabolic index of serum content in growth factors.