STUDY OF MICE IN WHICH THE TGF-BETA1 GENE HAS BEEN DISRUPTED

在TGF-β的三种亚型中，TGF-β 1是最丰富的，并且在损伤、修复和疾病发病机制中受到最剧烈的调节。虽然它们没有任何明显的发育缺陷，但通过靶向破坏而敲除TGF-β 1基因的小鼠在约3周龄时死于多灶性炎症性疾病和自身免疫性疾病。我们已经使用伤口愈合来确定特定的细胞功能和细胞-细胞相互作用，这些功能和细胞-细胞相互作用因TGF-β 1的丢失而改变。与基于外源性TGF-β 1的间接作用的预测相反，缺乏内源性蛋白质改善了皮肤伤口的愈合，提高了上皮再形成的速率，减少了肉芽组织的量，并改善了结缔组织重塑。我们还与Chuxia Deng（NIDDK）合作，研究Smads 2和3（TGF-β信号通路中的细胞质中间体）无效或杂合小鼠的伤口愈合。这些研究允许鉴定涉及伤口愈合的特定途径，并表明Smad 3而不是Smad 2介导TGF-β对上皮再生的抑制作用。在TGF-β 1缺失小鼠中的其他研究表明，电子传递链的几种细胞编码组分的mRNA表达受到抑制，这与肝脏细胞的高尔基体和线粒体中的超微结构异常的观察结果一致，心脏和肺，提示能量缺乏和囊泡转运受损。这是特别有趣的光从这个实验室的细胞内TGF-β 1定位到线粒体以前的发现。功能研究表明，虽然单个电子链组件的最大容量在无效小鼠中没有改变，但心脏组织的氧化能力显著降低。此外，对来自这些小鼠的肝细胞系的研究表明，与野生型细胞相比，空细胞具有降低的耗氧量。在体外用TGF-β处理无效或野生型细胞导致线粒体基因表达的快速上调，并部分恢复氧化代谢的缺陷。目前的研究旨在确定TGF-β 1调节细胞能量和线粒体基因表达的机制。 - 细胞能量学，生长因子，炎症，线粒体，TGF-β，

Of the three isoforms of TGF-beta, TGF-beta1 is both the most abundant and the most acutely regulated in injury, repair, and disease pathogenesis. Although they lack any obvious developmental defects, mice in which the TGF-beta1 gene has been knocked out by targeted disruption die at about 3 weeks of age of multifocal inflammatory disease and autoimmune symptomatology. We have used wound healing to identify specific cellular functions and cell-cell interactions which are altered by the loss of TGF-beta1. In contrast to predictions based on the vulnerary effects of exogenous TGF-beta1, lack of the endogenous protein improves healing of cutaneous wounds, enhancing the rate of re- epithelialization, reducing the amount of granulation tissue, and improving connective tissue remodeling. We are also collaborating with Chuxia Deng (NIDDK) to study wound healing in mice null or heterozygous for Smads 2 and 3, cytoplasmic intermediates in TGF-beta signaling pathways. These studies are permitting identification of specific pathways involved in wound healing and show that Smad3 and not Smad2 mediates suppressive effects of TGF-beta on re-epithelialization.Other studies in TGF-beta1 null mice have shown suppressed expression of the mRNAs for several mitochondrially encoded components of the electron- transport chain, consistent with observations of ultrastructural abnormalities in Golgi and mitochondria of cells of liver, heart, and lung of TGF-beta1 null mice suggestive of an energy deficit and impaired vesicular transport. This is particularly intriguing in light of previous findings from this laboratory of localization of intracellular TGF-beta1 to mitochondria. Functional studies have shown that whereas maximal capacity of individual electron chain components is not altered in the null mice, there is a significant decrease in the oxidative capacity of heart tissue. Moreover, studies with hepatocyte cell lines derived from these mice show that null cells have reduced oxygen consumption compared to wildtype cells. Treatment of either null or wildtype cells with TGF-beta in vitro results in rapid upregulation of expression of mitochondrial genes and restores, in part, the deficit in oxidative metabolism. Present investigations are aimed at determining the mechanism whereby TGF-beta1 regulates cellular energetics and expression of mitochondrial genes. - cell energetics, growth factors, Inflammation, mitochondria, TGF-beta,