Quality control mechanisms against misfolded rhodopsins in Drosophila.

针对果蝇中错误折叠视紫红质的质量控制机制。

• 批准号: 8664498
• 负责人: HYUNG D RYOO
• 金额: $ 33.8万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8664498
• 关键词: Affect; Age-Years; Alleles; Amino Acid Substitution; Animal Model; Attention; Binding; Biological; Biological Assay; Blindness; Cells; Cytoplasm; Development; Disease; Drosophila genus; Employee Strikes; Endoplasmic Reticulum; Endoplasmic Reticulum Degradation Pathway; Gene Dosage; Gene Expression; Genes; Genetic; Genetic Transcription; Goals; Hereditary Disease; Homologous Gene; Human; Inborn Genetic Diseases; Individual; Longevity; Mammalian Cell; Mediating; Messenger RNA; Modeling; Mutation; Outcome Study; Pathway interactions; Phosphoric Monoester Hydrolases; Phosphorylation; Process; Property; Protein Dephosphorylation; Proteins; Quality Control; RNA Binding; RNA Interference; RNA Recognition Motif; RNA Splicing; Regulation; Retina; Retinal; Retinal Degeneration; Retinitis Pigmentosa; Rhodopsin; Role; Signal Pathway; Signal Transduction; Stress; Testing; Therapeutic; Ubiquitin; Yeasts; age related; endonuclease; endoplasmic reticulum stress; fly; genome-wide; high throughput analysis; insight; interest; multicatalytic endopeptidase complex; mutant; novel; novel therapeutics; overexpression; phosphatase inhibitor; protective effect; protein complex; protein folding; protein misfolding; response; tool; transcription factor

Retinitis Pigmentosa is a group of inherited disorders that show a progressive loss of retinal function. One of the most common causes of Autosomal Dominant Retinitis Pigmentosa (ADRP) are mutations in the rhodopsin gene that disrupt its encoded protein's folding property. Our long-term goal is to understand how cells respond to stress caused by such rhodopsin proteins once they are synthesized in the endoplasmic reticulum (ER). As most cells have robust quality control mechanisms that can help eliminate such misfolded proteins from the ER, a better understanding of these mechanisms may have therapeutic implications. We focus on two specific ER quality control mechanisms that can help suppress retinal degeneration caused by misfolded rhodopsins. First is ER-Associated Degradation (ERAD), which refers to the ubiquitin-mediated degradation of misfolded proteins from the ER. Stimulation of ERAD can suppress retinal degeneration in a Drosophila model for ADRP, but the underlying mechanism remains poorly understood. In addition, ADRP may be suppressed by an intracellular signaling pathway activated by ER-stress, known as the Unfolded Protein Response (UPR). A central branch of the UPR is mediated by the unconventional splicing of xbp1 mRNA in the cytoplasm, leading to the synthesis of an active xbp1 transcription factor. Among the transcription targets of xbp1 include regulators of ERAD. To investigate mechanisms by which ERAD and the UPR suppress retinal degeneration in animal models of ADRP, we plan to use a combination of classical Drosophila genetics, cell biological analysis and high throughput RNAi assays. Specifically, we plan to investigate the precise mechanism by which misfolded rhodopsins are detected by the ERAD machinery and imported into the cytoplasm for degradation. In addition, we plan to study how the xbp1-mediated UPR pathway is regulated. We will test a specific hypothesis where xbp1 mRNA splicing is modulated by a specific phosphatase, and this phosphatase is in turn regulated by a regulatory subunit that binds to xbp1 mRNA. Any new genes or mechanisms identified through this approach will be examined for possible effects on retinal degeneration in a Drosophila model for ADRP, where an endogenous mutation in a rhodopsin encoding gene triggers a dominant form of age-related retinal degeneration. As the fly model shows a striking degree of similarity with the human condition, we believe that a successful outcome of this study may directly influence the development of new strategies against ADRP in humans.

视网膜色素变性是一组遗传性疾病，表现为视网膜功能的进行性丧失。常染色体显性遗传性视网膜色素变性(ADRP)最常见的原因之一是视紫红质基因突变，破坏了其编码蛋白的折叠特性。我们的长期目标是了解一旦这些视紫红质蛋白在内质网(ER)中合成，细胞如何应对这些视紫红质蛋白造成的压力。由于大多数细胞都有强大的质量控制机制，可以帮助从内质网中消除这种错误折叠的蛋白质，因此对这些机制的更好理解可能具有治疗意义。我们专注于两种特定的ER质量控制机制，这两种机制可以帮助抑制错误折叠的视紫红质引起的视网膜退化。第一种是内质网相关降解(ERAD)，它指的是泛素介导的内质网错误折叠蛋白的降解。刺激ERAD可以抑制ADRP果蝇模型的视网膜退行性变，但其潜在机制尚不清楚。此外，ADRP可能被内质网应激激活的细胞内信号通路抑制，称为未折叠蛋白反应(UPR)。UPR的一个中心分支是由XBP1 mRNA在细胞质中的非常规剪接介导的，导致合成活性XBP1转录因子。XBP1的转录靶标包括ERAD的调节因子。为了研究ERAD和UPR抑制ADRP动物模型视网膜变性的机制，我们计划结合经典的果蝇遗传学、细胞生物学分析和高通量RNAi分析。具体地说，我们计划研究ERAD机制检测错误折叠的视紫红质并将其输入细胞质进行降解的确切机制。此外，我们计划研究XBP1介导的UPR通路是如何调控的。我们将检验一个特定的假说，其中XBP1 mRNA的剪接受特定的磷酸酶调控，而该磷酸酶又由与XBP1 mRNA结合的调节亚单位调节。通过这种方法确定的任何新基因或机制将在adrp的果蝇模型中检查对视网膜退化的可能影响，在该模型中，视紫红质编码基因的内源性突变会触发一种主要形式的年龄相关性视网膜退化。由于果蝇模型显示出与人类状况惊人的相似程度，我们相信这项研究的成功结果可能直接影响到人类对抗ADRP的新策略的开发。