Essential Role of Very Long Chain Fatty Acids in Retinal Function

极长链脂肪酸在视网膜功能中的重要作用

• 批准号: 10018024
• 负责人: Martin-Paul Agbaga
• 金额: $ 36.25万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-30 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10018024
• 关键词: Adolescent; Affect; Age-Months; Alleles; Animal Model; Ataxia; Attenuated; Biochemical Reaction; Birth; Blindness; Brain; Cell Culture Techniques; Cells; Cerebellum; Cessation of life; Child; Deformity; Dehydration; Development; Disease; Disease Progression; Dominant-Negative Mutation; Enzymes; Essential Fatty Acids; Exons; Fatty Acids; Film; Fish Oils; Gait abnormality; Genes; Goals; Health; Human; In Vitro; Japanese Population; Knock-in; Knock-out; Life; Long-Evans Rats; Macular degeneration; Maintenance; Modeling; Molecular; Mus; Mutation; Neonatal; Nerve Degeneration; Outcome; Pathologic; Pathology; Patients; Permeability; Phenotype; Photoreceptors; Point Mutation; Polyunsaturated Fatty Acids; Property; Proteins; Public Health; Quality Control; Quality of life; Rattus; Retina; Retinal Degeneration; Role; Saturated Fatty Acids; Seizures; Skin; Spinocerebellar Ataxias; Stargardt' s disease; Structure; Testing; Testis; Therapeutic; Tissues; Very Long Chain Fatty Acid; Waxes; Work; autosomal dominant mutation; biophysical properties; cohort; design; early childhood; experimental study; fatty acid biosynthesis; human disease; in vivo; insight; keratinocyte; macula; macular dystrophy; meibomian gland; mortality; motor impairment; mutant; novel; skin lesion; sperm cell; targeted treatment; therapeutic target; tissue culture

Abstract Very long chain fatty acids (VLC-FA, ≥ C28) are synthesized by the Elongation of Very Long Chain Fatty Acids-4 (ELOVL4) enzyme and are essential for life such that depletion of tissue VLC-FA (due to knockout of ELOVL4) causes neonatal lethality. The ELOVL4 protein is expressed in the retina, Meibomian glands, brain, skin, and testes. In each of these tissues, the enzyme makes two different classes of VLC-FA. One class is VLC-saturated fatty acids (VLC-SFA) that are found mainly in the skin, brain, Meibomian glands and tear film. The other is VLC-polyunsaturated fatty acids (VLC-PUFA) that are found in the retina, testes and sperm. Since VLC-FA are essential for the normal function of these tissues, mutations in ELOVL4 cause distinct tissue- specific disorders like Stargardt-like macular dystrophy (STGD3), spinocerebellar ataxia-34 (SCA34), skin pathologies, seizures and death. However, the mechanisms by which one tissue makes mainly VLC-SFA and the other VLC-PUFA, and how the VLC-FA exert their importance in each tissue remain unknown. We seek to understand the molecular basis of this phenomenon with the goal of developing therapeutic targets for attenuating disease progression. Our lab and others have shown that conditional deletion of retinal Elovl4 or expression of the mutant Elovl4 leads to depletion of VLC-SFA and VLC-PUFA, which affect retinal structure and function. We also showed that the STGD3 mutant ELOVL4 lacks VLC-PUFA biosynthesis and exerts a dominant negative effect on wild type ELOVL4 (WT ELOVL4) in vitro and in vivo causing decreased VLC-FA biosynthesis. These suggest that VLC-FA are necessary for maintenance of photoreceptor health and function. To understand how one set of mutations causes vision loss and another causes ataxia, we successfully generated a Long Evans (LE) rat knock-in model of the SCA34 ELOVL4 mutation (c.736T>G) that recapitulates the human disorder. Consequently, we now have animal models of STGD3 and SCA34. We hypothesize that tissue-specific factors determine which type of fatty acid is made in specific tissues and that the pathological differences found in patients with STGD3 and SCA34 result from differences in the types of VLC-FAs produced directly by the mutant enzymes or from effects of the mutant enzymes on VLC-FA produced by the wild type ELOVL4 enzyme. We propose two specific aims: 1) To determine how different ELOVL4-expressing tissues control the VLC-SFA and VLC-PUFA biosynthetic activity of ELOVL4. 2) To determine how the different ELOVL4 mutations affect the quality and quantity of the VLC-FA that they synthesize. The results would provide better mechanistic insight into the relative contributions of the depletion of VLC-FA and the mutant ELOVL4 in the progression of the mutant ELOVL4 disorders. This could potentially provide an immediate positive impact by paving the way for development of potential therapeutic approaches to rescue these disorders.

抽象的 极长链脂肪酸（VLC-FA，≥C28）是通过极长链脂肪的延伸合成的 Acids-4 (ELOVL4) 酶对生命至关重要，因此组织 VLC-FA 的消耗（由于敲除 ELOVL4) 导致新生儿死亡。 ELOVL4 蛋白在视网膜、睑板腺、大脑、 皮肤、睾丸。在这些组织中，酶会产生两种不同类别的 VLC-FA。一类是 VLC 饱和脂肪酸 (VLC-SFA) 主要存在于皮肤、大脑、睑板腺和泪膜中。 另一种是 VLC-多不饱和脂肪酸 (VLC-PUFA)，存在于视网膜、睾丸和精子中。自从 VLC-FA 对于这些组织的正常功能至关重要，ELOVL4 的突变会导致不同的组织- 特定疾病，如 Stargardt 样黄斑营养不良 (STGD3)、脊髓小脑性共济失调 34 (SCA34)、皮肤病 病理、癫痫发作和死亡。然而，一种组织主要产生 VLC-SFA 和 其他 VLC-PUFA 以及 VLC-FA 如何在每种组织中发挥其重要性仍然未知。我们力求 了解这种现象的分子基础，旨在开发治疗靶点 减缓疾病进展。我们的实验室和其他实验室已经表明，有条件地删除视网膜 Elovl4 或 突变体 Elovl4 的表达导致 VLC-SFA 和 VLC-PUFA 的消耗，从而影响视网膜结构 和功能。我们还表明 STGD3 突变体 ELOVL4 缺乏 VLC-PUFA 生物合成并发挥 对野生型 ELOVL4 (WT ELOVL4) 的体外和体内显性负效应导致 VLC-FA 减少 生物合成。这些表明 VLC-FA 对于维持光感受器的健康和功能是必需的。 为了了解一组突变如何导致视力丧失而另一组突变如何导致共济失调，我们成功地 生成了 SCA34 ELOVL4 突变 (c.736T>G) 的 Long Evans (LE) 大鼠敲入模型， 概括了人类的混乱。因此，我们现在有了 STGD3 和 SCA34 的动物模型。我们 假设组织特异性因素决定特定组织中产生哪种类型的脂肪酸，并且 STGD3 和 SCA34 患者中发现的病理差异是由于疾病类型的差异造成的 由突变酶直接产生或由突变酶对 VLC-FA 的作用产生的 VLC-FA 由野生型 ELOVL4 酶产生。我们提出两个具体目标：1）确定差异有多大 ELOVL4表达组织控制ELOVL4的VLC-SFA和VLC-PUFA生物合成活性。 2) 至 确定不同的 ELOVL4 突变如何影响它们所产生的 VLC-FA 的质量和数量 合成。结果将为了解耗尽的相对贡献提供更好的机制见解 VLC-FA 和突变 ELOVL4 在突变 ELOVL4 疾病进展中的作用。这可能有可能 通过为潜在治疗方法的开发铺平道路，提供直接的积极影响 来拯救这些疾病。