Mechanistic insight into the pathology of polyalanine expansion disorders revealed by a mouse model for X linked hypopituitarism.
Mechanistic insight into the pathology of polyalanine expansion disorders revealed by a mouse model for X linked hypopituitarism.
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DOI：
10.1371/journal.pgen.1003290
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发表时间：
2013
期刊：
影响因子：
4.5
通讯作者：
Thomas P
中科院分区：
文献类型：
--
作者：
Hughes J;Piltz S;Rogers N;McAninch D;Rowley L;Thomas P
转录因子中多聚丙氨酸的扩增与八种不同的先天性人类疾病有关。据认为，在每种情况下，多聚丙氨酸的扩增都会导致蛋白质错误折叠，从而消除蛋白质功能。错误折叠的蛋白质在体外表达时形成聚集体；然而，目前尚不清楚聚集是否与体内这些疾病相关。为了研究这个问题，我们利用胚胎干 (ES) 细胞的定向诱变来产生具有 Sox3 (Sox3-26ala) 多聚丙氨酸扩增突变的小鼠，该突变与人类 X 连锁垂体功能减退症 (XH) 相关。通过研究 ES 细胞和嵌合小鼠，我们发现内源性多聚丙氨酸扩增的 SOX3 在体内不会形成蛋白质聚集体，而是以显着降低的水平存在于突变细胞的细胞核内。重要的是，嵌合胚胎的残留突变蛋白能够挽救原肠胚形成的障碍，但不足以维持下丘脑的正常发育，下丘脑是 Sox3 无效胚胎和 XH 个体中功能受损的区域。总之，这些数据提供了与疾病相关的 PA 突变蛋白的第一个明确例子，该突变蛋白既是核的又是功能性的，从而表现为部分功能丧失的等位基因。丙氨酸是生成蛋白质的 20 种氨基酸组成部分之一。近 500 种人类蛋白质含有长度从 4 到 20 个氨基酸不等的连续丙氨酸残基。虽然这些聚丙氨酸 (PA) 束的功能仍然未知，但它们很有趣，因为 DNA 变化（突变）使它们的长度增加到阈值以上，导致九种不同的人类疾病。体外研究表明，扩展的 PA 蛋白会错误折叠和聚集，这表明可能存在一种共同的“功能获得”机制支撑这组疾病。然而，这些数据很难与遗传研究相一致，遗传研究表明大多数 PA 突变会导致蛋白质功能丧失。因此，为了研究 PA 疾病的病理机制，我们构建了 X 连锁垂体功能减退症 (XH) 小鼠模型，这是一种由 SOX3 蛋白中 PA 扩增引起的疾病。引人注目的是，我们发现小鼠版本的致病蛋白几乎完全从细胞中清除，并且在体内不会形成聚集体。这些数据解释了为什么这种类型的突变会导致蛋白质功能丧失，并揭示了自然限制 PA 延伸长度的原因。
Polyalanine expansions in transcription factors have been associated with eight distinct congenital human diseases. It is thought that in each case the polyalanine expansion causes misfolding of the protein that abrogates protein function. Misfolded proteins form aggregates when expressed in vitro; however, it is less clear whether aggregation is of relevance to these diseases in vivo. To investigate this issue, we used targeted mutagenesis of embryonic stem (ES) cells to generate mice with a polyalanine expansion mutation in Sox3 (Sox3-26ala) that is associated with X-linked Hypopituitarism (XH) in humans. By investigating both ES cells and chimeric mice, we show that endogenous polyalanine expanded SOX3 does not form protein aggregates in vivo but rather is present at dramatically reduced levels within the nucleus of mutant cells. Importantly, the residual mutant protein of chimeric embryos is able to rescue a block in gastrulation but is not sufficient for normal development of the hypothalamus, a region that is functionally compromised in Sox3 null embryos and individuals with XH. Together, these data provide the first definitive example of a disease-relevant PA mutant protein that is both nuclear and functional, thereby manifesting as a partial loss-of-function allele. Alanine is one of the 20 amino acid building blocks from which proteins are generated. Nearly 500 human proteins contain stretches of consecutive alanine residues ranging from 4 to 20 amino acids in length. Whilst the function of these polyalanine (PA) tracts remains unknown, they are interesting because DNA changes (mutations) that increase their length above a threshold are responsible for nine different human disorders. In vitro studies indicate that expanded PA proteins misfold and aggregate, suggesting that there may be a common “gain-of-function” mechanism that underpins this group of disorders. However, these data are difficult to reconcile with genetic studies, which indicate that most PA mutations cause protein loss-of-function. Therefore, to investigate the pathological mechanism of PA disorders we generated a mouse model of X-linked Hypopituitarism (XH), a disease caused by PA expansion in the SOX3 protein. Strikingly, we found that the mouse version of the disease-causing protein was almost completely cleared from cells and that aggregates do not form in vivo. These data explain why this type of mutation causes protein loss-of-function and reveals why nature limits the length of PA stretches.
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影响因子：
3.5
作者：
Kitamura, Kunio;Itou, Yukiko;Goto, Yu-ichi
通讯作者：
Goto, Yu-ichi
影响因子：
3.5
作者：
Calado, A;Tomé, FMS;Carmo-Fonseca, M
通讯作者：
Carmo-Fonseca, M
婴儿痉挛综合征 Arx(GCG)10+7 的三联体重复扩增遗传小鼠模型，伴有神经元病、婴儿期痉挛、持续性癫痫发作以及成人认知和行为障碍。
影响因子：
5.3
作者：
Price, Maureen G.;Yoo, Jong W.;Burgess, Daniel L.;Deng, Fang;Hrachovy, Richard A.;Frost, James D., Jr.;Noebels, Jeffrey L.
通讯作者：
Noebels, Jeffrey L.
影响因子：
0.7
作者：
Burkitt Wright EM;Perveen R;Clayton PE;Hall CM;Costa T;Procter AM;Giblin CA;Donnai D;Black GC
通讯作者：
Black GC
DOI：
10.1073/pnas.0803078105
发表时间：
2008-08-19
影响因子：
11.1
作者：
Wataya, Takafumi;Ando, Satoshi;Sasai, Yoshiki
通讯作者：
Sasai, Yoshiki