Beta-Amyloid & Cell Death Mechanisms in Skeletal Muscle

描述(摘自申请者摘要)：包涵体肌炎(IBM) 是50岁以上患者最常见的肌肉疾病。IBM股票 另一种与年龄相关的退行性疾病阿尔茨海默氏症的几个特征 疾病(AD)：1)有散发性和常染色体遗传型，2) 局部炎症聚集是特征性的，但具有免疫抑制作用 治疗效果微乎其微，以及3)AD相关疾病的累积 蛋白质是组织病理学的标志。刚果红-反应型矿床 由β-淀粉样多肽(Abeta)组成的是最显著的特征。在……里面 与AD的细胞外淀粉样斑块相比，AD的淀粉样沉积 IBM是细胞内的。其他几种蛋白质在细胞内积累在 IBM的空泡化肌纤维，包括β-淀粉样前体的其他表位 蛋白质，过度磷酸化的细丝组成的微管相关 蛋白tau、泛素、细胞内的Pron蛋白和细胞周期蛋白依赖的蛋白 5(CDK5)。 IBM肌肉细胞丢失的机制仍然是个谜。众所周知，阿贝塔 诱导培养中和某些细胞中神经元的程序性细胞死亡(凋亡) 阿尔茨海默病转基因小鼠模型。在目标1中，申请者 假设培养的骨骼中Abeta在细胞内蓄积 肌管会诱导细胞凋亡。Aβ沉积是用一种 可诱导启动子、异源病毒基因转移系统或直接 注射。他们将研究蛋白酶体和parkin基因在 蛋白质堆积的起源。在目标2中，Abeta被确立为 肌毒素通过对人类IBM活检样本的彻底检查，为 Aβ蓄积与几种细胞凋亡标志物的相关性小白鼠 肌肉在直接注射Abeta编码后进行类似的分析 腺病毒基因构建。他们的第二个假设是 细胞内Abeta对Akt依赖的肌细胞存活产生不利影响 在目标3中，我们将确定Abeta是否抑制Akt的活性。 此外，申请者将寻求Abeta导致有害的证据 细胞重新进入发育甚至细胞周期的尝试，与 Akt、p21Cip1/WAFL或细胞周期蛋白D功能紊乱。有关tau的证据 将寻求不受阻碍的GSK-3β活性的过度磷酸化。在AIM 4探讨Abeta对Akt抑制作用的功能意义 Akt激活是否能保护被迫过度表达Abeta的肌肉细胞 死于细胞死亡。虽然其中一些发现可能与神经元有关 系统，它们将提供对Abeta损伤的新机制的洞察和 关键基因对细胞存活、复制和凋亡的复杂调控 求生信号控制点。

DESCRIPTION (Adapted from applicant's abstract): Inclusion Body Myositis (IBM) is the most common muscle disorder in patients over 50 years of age. IBM shares several features with another age-related degenerative disorder, Alzheimer's disease (AD): 1) there are both sporadic and autosomal inherited forms, 2) local inflammatory collections are characteristic but immunosuppressive therapies are only marginally effective, and 3) accumulations of AD-related proteins are a histopathological hallmark. Congo red- reactive deposits consisting of the beta-amyloid peptide (Abeta) are the most notable feature. In contrast with the extra-cellular amyloid plaques of AD, the amyloid deposits of IBM are intracellular. Several other proteins accumulate intracellularly in the vacuolated myofibers of IBM including other epitopes of beta-amyloid precursor protein, hyperphosphorylated filaments comprised of the microtubule-associated protein tau, ubiquitin, the cellular prion protein, and cyclin dependent kinase 5 (cdk5). The mechanism of muscle cell loss in IBM remains a mystery. Abeta is known to induce programmed cell death (apoptosis) of neurons in culture and in some transgenic mouse models for Alzheimer's disease. In Aim 1, the applicants hypothesize that intracellular accumulation of Abeta in cultured skeletal muscle myotubes will induce apoptosis. Abeta deposition is provoked using an inducible promoter, a heterologous viral gene transfer system, or by direct injection. They will examine the role of the proteasome and the parkin gene in the genesis of protein accumulations. In Aim 2, Abeta is established as a myotoxins by a thorough examination of human IBM biopsy specimens, for a correlation between Abeta accumulation and several markers of apoptosis. Mouse muscle is similarly analyzed after direct injection of an Abeta-encoding adenoviral gene construct. Their 2nd hypothesis is that deposition of intracellular Abeta adversely affects Akt kinase-dependent muscle cell survival pathways and in Aim 3 we will determine if Abeta inhibits Akt activity. Furthermore, the applicants will seek evidence that Abeta induces deleterious attempts by cells to re-enter the developmental or even the cell cycle, related to Akt, p21 Cip1/Wafl or cyclin D dysfunction. Evidence for tau hyperphosphorylation from unhindered GSK-3beta activity will be sought. In Aim 4 the functional significance of Akt inhibition by Abeta is examined by asking whether Akt activation will protect muscle cells forced to overexpress Abeta from cell death. While some of the findings may be relevant to neuronal systems, they will provide insight into a novel mechanism of Abeta injury and the complex regulation of cell survival, replication and apoptosis from a key survival signal control point.