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: 8113397
• 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: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8113397
• 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; public health relevance; response; tool; transcription factor

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: Mutations in the rhodopsin gene are responsible for approximately a quarter of autosomal dominant forms of Retinitis Pigmentosa (ADRP), a genetic disease that leads to blindness in individuals 40 ~ 60 years of age. Thus, a better understanding of the mechanisms that help the elimination of misfolded rhodopsins may have a direct impact on developing new therapeutic strategies against this disease.

描述（由申请人提供）：色素性视网膜炎是一组显示视网膜功能进行性丧失的遗传性疾病。常染色体显性遗传性视网膜色素变性 (ADRP) 的最常见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此类视紫红质蛋白在内质网（ER）中合成后，细胞如何应对它们引起的压力。由于大多数细胞具有强大的质量控制机制，可以帮助消除内质网中的此类错误折叠蛋白质，因此更好地了解这些机制可能具有治疗意义。我们专注于两种特定的 ER 质量控制机制，可以帮助抑制由错误折叠的视紫红质引起的视网膜变性。首先是内质网相关降解（ERAD），它是指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 果蝇模型中的视网膜变性，但其潜在机制仍知之甚少。此外，ADRP 可能会被 ER 应激激活的细胞内信号通路（称为未折叠蛋白反应 (UPR)）所抑制。 UPR 的中央分支由细胞质中 xbp1 mRNA 的非常规剪接介导，导致活性 xbp1 转录因子的合成。 xbp1 的转录靶标包括 ERAD 的调节因子。为了研究 ERAD 和 UPR 在 ADRP 动物模型中抑制视网膜变性的机制，我们计划结合使用经典的果蝇遗传学、细胞生物学分析和高通量 RNAi 测定。具体来说，我们计划研究 ERAD 机器检测错误折叠视紫红质并将其导入细胞质进行降解的精确机制。此外，我们计划研究xbp1介导的UPR通路是如何被调控的。我们将测试一个特定的假设，其中 xbp1 mRNA 剪接由特定磷酸酶调节，而该磷酸酶又受到与 xbp1 mRNA 结合的调节亚基的调节。通过这种方法鉴定的任何新基因或机制都将在 ADRP 果蝇模型中检查对视网膜变性的可能影响，其中视紫红质编码基因的内源性突变会引发与年龄相关的视网膜变性的主要形式。由于果蝇模型显示出与人类状况惊人的相似性，我们相信这项研究的成功结果可能会直接影响人类对抗 ADRP 新策略的开发。 公共健康相关性：大约四分之一的常染色体显性视网膜色素变性 (ADRP) 是由视紫红质基因突变引起的，ADRP 是一种导致 40 至 60 岁个体失明的遗传性疾病。因此，更好地了解有助于消除错误折叠视紫红质的机制可能会对开发针对这种疾病的新治疗策略产生直接影响。