[转贴]一篇综述

一篇综述
肌肉的数量和功能随年龄增长而消退，GH/IGF1作用轴对肌肉数量的调节十分重要。

除了肝脏外，其它组织也能产生IGF1。IGF1有局部全身的和2种形式，分别具有不同功能。

本文作者克隆到骨骼肌中2种不同的IGF1，它们是IGF1基因的不同剪接形式。其中一种是受运动刺激产生的，又称为MGF（mechanogrowth factor）；另一种与全身型或肝脏型（IGF-1Ea）的相似，它十分重要，提供上调蛋白合成所需要的成熟IGF1。MGF与全身型IGF-1Ea的不同之处在于它的对应于激活肌肉卫星细胞（干细胞）的肽序列不同。

因此，这2种IGF1具有不同的作用，对于调节肌肉生长都很重要。生长激素治疗显然是上调了IGF1基因的表达水平，当与张力运动结合时更多的IGF1成为MGF形式。

老年人本身的NGF水平是下降的，他们可以通过锻炼提高MGF的水平。

本文还讨论了用MGF来治疗老年性肌肉消退的可能性。

Ann N Y Acad Sci. 2004 Jun;1019:294-8. Related Articles, Links


Age-related muscle loss and progressive dysfunction in mechanosensitive growth factor signaling.

Goldspink G.

Division of Surgery, Royal Free and University College Medical School, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom. goldspink@rfc.ucl.ac.uk

Loss of muscle mass and function (sarcopenia) is one of the most marked problems associated with aging because it has major healthcare as well as socioeconomic implications. The growth hormone/IGF-I axis is regarded as an important regulator of muscle mass. However, it is now appreciated that other tissues in addition to the liver express IGF-I. Also, there are local as well as systemic forms of IGF-I that have different functions. We cloned two different IGF-Is that are expressed by skeletal muscle, and both are derived from the IGF-I gene by alternative splicing. One of these is expressed in response to physical activity, which has now been called "mechanogrowth factor" (MGF). The other is similar to the systemic or liver type (IGF-IEa) and is important as the provider of mature IGF-I required for upregulating protein synthesis. MGF differs from systemic IGF-IEa in that it has a different peptide sequence that is responsible for activating muscle satellite (stem) cells. Therefore, it appears these two forms of IGF-I have different actions and that they are important regulators of muscle growth. Growth hormone treatment apparently upregulates the level of IGF-I gene expression, and when it is combined with resistance exercise more is spliced toward MGF. This results in an increase in muscle cross-sectional area in the elderly subjects who otherwise would produce less MGF. The possibility of ameliorating sarcopenia using MGF delivered as a peptide or by gene therapy will be discussed.

Publication Types:
Review
Review, Tutorial

PMID: 15247032 [PubMed - indexed for MEDLINE]

GOOD!