Functional interactions among retinoschisin and its binding partners

视黄体素及其结合伙伴之间的功能相互作用

• 批准号: 8485191
• 负责人: GLADYS Y KO
• 金额: $ 21.51万
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8485191
• 关键词: Adhesions; Adolescent; Amino Acid Sequence; Amino Acids; Binding; Biological Assay; Blindness; Ca(2+)-Transporting ATPase; Calcium Channel; Cell membrane; Cell physiology; Cells; Chickens; Clinical; Complex; Data; Diagnosis; Disease; Early Diagnosis; Electroretinography; Future; Gene Mutation; Genes; Goals; Homeostasis; Human; Impairment; Intervention; Knowledge; Link; Macular degeneration; Membrane; Mission; Molecular; Mutation; N-terminal; Na(+)-K(+)-Exchanging ATPase; National Eye Institute; Nature; Night Blindness; Outcome; Patients; Phenotype; Photoreceptors; Physiology; Play; Point Mutation; Prevalence; Prevention; Protein Fragment; Proteins; Public Health; Pump; Regulation; Research; Retina; Retinal; Retinal Cone; Role; Severities; Structure; United States National Institutes of Health; Variant; Vision; Visual Acuity; Work; X-Linked Retinoschisis; XLRS1 protein; base; extracellular; hybrid protein; loss of function; loss of function mutation; male; neurotransmitter release; novel; programs; public health relevance; response; retinal neuron; voltage; yeast two hybrid system

DESCRIPTION (provided by applicant): X-linked juvenile retinoschisis (XLRS) is a leading cause of macular degeneration in juvenile males, with a worldwide prevalence from 1:5000 to 1:20,000. The phenotypes of XLRS are caused by mutations of RS1, the gene encoding retinoschisin, an extracellular octameric protein that participates in retinal cell organization an adhesion. Because XLRS progression and severity is highly variable, early diagnosis and potential clinical intervention is very challenging. Retinoschisin is known to interact with variou molecules in the plasma membrane, including the L-type voltage-gated calcium channel ¿1D subunit (L-VGCC¿1D). However, how retinoschisin interacts with its binding partners and its functional roles in the retina are not completely clear. Understanding the molecular nature of the components that interact with retinoschisin will allow us to more fully understand the roles of retinoschisin in retinal cell physiology and function, which will provide new information for making early diagnosis and potential clinical intervention possible. Previously, we demonstrated that L- VGCC¿1D is a binding partner of retinoschisin in the chick retina. The L-VGCCs are essential for neurotransmitter release and intracellular Ca2+ homeostasis in photoreceptors and other retinal neurons. Retinoschisin binds a 500 amino acid N-terminal region of chicken L-VGCC¿1D, which is highly conserved with human L-VGCC¿1D and L-VGCC¿1F subunits. In humans, mutations of L-VGCC¿1F cause incomplete congenital stationary night blindness (CSNB2). Our finding may explain why both XLRS and CSNB2 patients share a similar loss of cone responses. We have further identified a new binding partner of retinoschisin, the plasma membrane Ca2+-ATPase (PMCA1), a Ca2+ pump that is important in excreting excessive intracellular Ca2+ from photoreceptors. Our central hypothesis is that retinoschisin is necessary for plasma membrane retention of PMCA1, and there is a functional interaction among retinoschisin, L-VGCC, and PMCA1 to regulate intracellular Ca2+ homeostasis in photoreceptors. Our research goal is to understand how retinoschisin interacts with L-VGCCs and PMCA1, and how this dynamic trio regulates intracellular Ca2+ homeostasis through the following specific aims: Aim 1. Determine the functional interaction between retinoschisin (RS1) and PMCA1; Aim 2. Determine the molecular sequences responsible for the physical interactions between RS1 and PMCA1 / L-VGCC¿1D; Aim 3. Determine the functional interaction among RS1, L-VGCC1D, and PMCA1 in intracellular Ca2+ homeostasis. We expect to demonstrate: 1. Loss-of- function mutations of RS1 will decrease PMCA1 membrane retention; 2. Specific molecular sequences of RS1, L-VGCC¿1D, and PMCA1 responsible for their physical interactions; 3. Interactions among RS1, L-VGCC1D, and PMCA1 contribute to intracellular Ca2+ homeostasis. Impact: This research program will reveal how retinoschisin interacts with its binding partners, specifically L-VGCCs and PMCA1, and new roles of retinoschisin in photoreceptor physiology and function.

描述（由申请人提供）：X连锁青少年视网膜劈裂症（XLRS）是青少年男性黄斑变性的主要原因，全球患病率为1:5000至1:20,000。 XLRS 的表型是由 RS1 突变引起的，RS1 是编码视网膜分裂素的基因，视网膜分裂素是一种参与视网膜细胞组织和粘附的细胞外八聚体蛋白。由于 XLRS 的进展和严重程度变化很大，因此早期诊断和潜在的临床干预非常具有挑战性。已知 Retinoschisin 与质膜中的各种分子相互作用，包括 L 型电压门控钙通道 ¿1D 亚基 (L-VGCC ¿1D)。然而，视网膜劈裂素如何与其结合伙伴相互作用以及其在视网膜中的功能作用尚不完全清楚。了解与视网膜劈裂素相互作用的成分的分子性质将使我们能够更全面地了解视网膜劈裂素在视网膜细胞生理和功能中的作用，这将为早期诊断和潜在的临床干预提供新的信息。之前，我们证明了 L-VGCC¿1D 是小鸡视网膜中视网膜裂素的结合伴侣。 L-VGCC 对于光感受器和其他视网膜神经元中的神经递质释放和细胞内 Ca2+ 稳态至关重要。 Retinoschisin 结合鸡 L-VGCC¿1D 的 500 个氨基酸的 N 端区域，该区域与人 L-VGCC¿1D 和 L-VGCC¿1F 亚基高度保守。在人类中，L-VGCC¿1F 突变会导致不完全先天性静止性夜盲症 (CSNB2)。我们的发现可以解释为什么 XLRS 和 CSNB2 患者都有相似的视锥反应损失。我们进一步鉴定了视网膜裂素的新结合伙伴，即质膜 Ca2+-ATP 酶 (PMCA1)，它是一种 Ca2+ 泵，对于从光感受器排出过量的细胞内 Ca2+ 非常重要。我们的中心假设是，视网膜劈裂素对于 PMCA1 的质膜保留是必需的，并且视网膜劈裂素、L-VGCC 和 PMCA1 之间存在功能相互作用，可调节光感受器的细胞内 Ca2+ 稳态。我们的研究目标是了解视网膜劈裂素如何与 L-VGCC 和 PMCA1 相互作用，以及这个动态三重奏如何通过以下具体目标调节细胞内 Ca2+ 稳态： 目标 1. 确定视网膜劈裂素 (RS1) 和 PMCA1 之间的功能相互作用；目标 2. 确定负责 RS1 和 PMCA1 / L-VGCC¿1D 之间物理相互作用的分子序列；目标 3. 确定 RS1、L-VGCC1D 和 PMCA1 在细胞内 Ca2+ 稳态中的功能相互作用。我们期望证明： 1. RS1 功能丧失突变将降低 PMCA1 膜保留； 2. RS1、L-VGCC¿1D 和 PMCA1 的特定分子序列负责它们的物理相互作用； 3. RS1、L-VGCC1D 和 PMCA1 之间的相互作用有助于细胞内 Ca2+ 稳态。影响：该研究项目将揭示视网膜劈裂素如何与其结合伙伴（特别是 L-VGCC 和 PMCA1）相互作用，以及视网膜劈裂素在光感受器生理学和功能中的新作用。