Structural and Molecular Mechanisms for Dysregulation of Protein Kinase C Gamma in Cerebellar Ataxia

摘要/摘要 我们提出的研究的总体愿景是了解结构、分子和细胞 蛋白激酶 C γ (PKCg) 种系突变驱动神经细胞的机制 退行性疾病脊髓小脑性共济失调 14 (SCA14)。 PKCg 是一种 Ca2/二酰基甘油调节的激酶 仅在神经元中表达，包括浦肯野细胞，其退化是近 50 SCA 的亚型。我们组建了一支在结构领域拥有广泛且互补的专业知识的团队 激酶生物学和 PKC 机制，以了解这些突变如何改变结构和 PKCg 的功能有助于疾病表型。推动该提议的假设是 突变集中在 PKCg 的特定区域，破坏自抑制接触以增强其 通过避免正常质量控制退化的新颖机制来进行活性。这种逃避 降解可能是共济失调突变的一个独特特征，因为与癌症相关的突变会破坏 自抑制接触会破坏 PKC 的稳定性并使其降解。这种逃避正常品质的行为 控制允许异常活跃的 PKCg 增强其信号输出，这在浦肯野细胞中 小脑导致退化。此外，我们假设 PKCg 增强的信号传导可能 一般而言，SCA 是 SCA 病理学的基础，因为大部分 SCA 是由蛋白质突变引起的 控制 Ca2 稳态或信号传导。我们的目标是将计算、结构、生物化学、 活细胞成像和磷酸蛋白质组学方法来了解分子细节 与疾病相关的 PKCg 突变会影响功能，未来的长期目标是利用该突变 治疗这种毁灭性疾病的知识。

Summary/Abstract The overall vision of our proposed research is to understand the structural, molecular, and cellular mechanisms by which germline mutations in protein kinase C gamma (PKCg) drive the neuro- degenerative disease Spinocerebellar Ataxia 14 (SCA14). PKCg is a Ca2+/diacylglycerol-regulated kinase expressed only in neurons, including Purkinje cells whose degeneration is a hallmark of the almost 50 subtypes of SCA. We have assembled a team with extensive and complementary expertise in structural biology of kinases and in PKC mechanisms to understand how these mutations alter the structure and function of PKCg to contribute to the disease phenotype. The hypothesis driving this proposal is that mutations are concentrated at specific regions of PKCg that break autoinhibitory contacts to enhance its activity by a novel mechanism that evades normal quality control degradation. This evasion of degradation may be a unique feature of the Ataxia mutations as cancer-associated mutations that break autoinhibitory contacts destabilize PKC and shunt it to degradation. Such evasion of normal quality control allows aberrantly active PKCg to enhance its signaling output, which in Purkinje cells in the cerebellum leads to degeneration. Furthermore, we hypothesize that enhanced signaling by PKCg may underlie the pathology of SCA, in general, as a large fraction of SCAs are caused by mutations in proteins that control Ca2+ homeostasis or signaling. We aim to combine computational, structural, biochemical, live-cell imaging, and phosphoproteomics approaches to understand the molecular details of how disease-associated mutations in PKCg impact function, with the long-term future goal of using this knowledge to treat this devastating disease.