mt-Nd2 and Resistance to Autoimmune Diabetes

描述(申请人提供)：线粒体(Mt)在细胞能量产生和细胞死亡中起关键作用。β细胞的功能与线粒体紧密相连；因为胰岛素合成和葡萄糖刺激的胰岛素分泌都需要线粒体ATP的产生。在此背景下，有关线粒体DNA(MtDNA)突变与人类糖尿病(T2D)家系相关的报告占人类T2D的1%。然而，mtDNA突变通常与自身免疫性1型糖尿病(T1D)相关，尽管在高危人群和T1D倾向于NOD与T1D抗性ALR小鼠的杂交中，mt-ND2基因C到A的转换导致亮氨酸到蛋氨酸的替换与T1D的保护作用有关。该应用程序的目标是了解这种单一氨基酸的变化如何改变对T1D的抵抗力。对T1D易感性的遗传分析主要集中在控制异常免疫细胞功能的候选基因上，而对可能在细胞水平上导致易感性或耐药性的基因关注较少。来自ALR小鼠品系的胰岛对自身免疫效应器的功能损伤和杀伤保持着不同寻常的遗传抵抗力。我们的结果将部分ALR衍生的T1d抗性与mt-Nd2a联系起来。虽然该等位基因并不能阻止在NOD遗传背景下自发的T1D的发展，但ALR衍生的遗传变异实际上确实保护了β细胞免受细胞毒性T淋巴细胞以及联合细胞因子的破坏。我们已经确定，这种抗性源于促凋亡应激不能诱导线粒体活性氧物种。我们的目标是了解该基因在细胞抵抗自身免疫杀伤中所起的作用。在具体目标1中，我们将确定 编码mt-Nd2a的细胞和初级胰岛抵抗肿瘤坏死因子受体家族成员TNFR1和Fas介导的破坏的机制。目的2将扩大研究，以确定编码mt-ND2a的胰岛细胞用于避免CTL溶解的机制。具体目标3将使用人类胰岛来确认抵抗细胞破坏的机制，以及使用人类杂合体细胞来测试人类mt-ND2等位基因是否改变了人类细胞死亡的特征。按照提议，这些研究将提供关于导致人类贝塔细胞死亡的早期凋亡信号的有意义的数据，以及对ND2a如何保护人类贝塔细胞的见解。

DESCRIPTION (provided by applicant): Mitochondria (mt) play key roles in cellular energy production and cell death. Beta cell function is tightly linked to mitochondria; as both insulin synthesis and glucose stimulated insulin secretion require mitochondrial ATP production. In this context, reports of mitochondrial DNA (mtDNA) mutations associated with diabetes (T2D) pedigrees in humans account for up to 1% of human T2D. However, mutations in mtDNA are not commonly associated with autoimmune Type 1 diabetes (T1D), although a C to A transversion resulting in a leucine to methonine substitution in the mt-ND2 gene has been associated with protection from T1D in both an at risk human population and in crosses of the T1D-prone NOD with T1D-resistant ALR mice. The goal of this application is to understand how this single amino acid change modifies resistance to T1D. Genetic analysis of T1D susceptibility has focused attention on candidate genes controlling aberrant immune cell function with little focus on genes that may contribute susceptibility or resistance at the ¿ cell level. Pancreatic islets from the ALR mouse strain maintain an unusual genetic resistance to functional impairment and killing by autoimmune effectors. Our results have linked some of the ALR-derived T1D resistance to mt- Nd2a. While this allele does not prevent the development of spontaneous T1D when introgressed into the NOD genetic background, the ALR-derived genetic variant does in fact protect beta cells from destruction by cytotoxic T lymphocytes as well as combined cytokines. We have determined that this resistance stems from the inability of pro-apoptotic stress to induce mt reactive oxygen species. Our goal is to understand the role this gene plays in ¿ cell resistance to autoimmune killing. In specific aim 1 we will determine the mechanism by which mt-Nd2a encoding ¿ cells and primary islets resist destruction mediated by members of the Tumor Necrosis Factor Receptor family, TNFR1 and Fas. Aim 2 will extend the studies to determine the mechanisms utilized by mt-Nd2a encoding islet cells to avert lysis by CTL. Specific aim 3 will use human islets to confirm mechanisms of resistance to ¿ cell destruction as well as cybrid human ¿ cells to test if the human alleles of mt-ND2 alter the characteristics of human ¿ cell death. The studies, as proposed, will provide meaningful data on both the early apoptotic signals that result in human beta cell death as well as insights into how ND2a protects human beta cells.