The Role of Phospholipid Turnover in Membrane Protein Function

磷脂周转在膜蛋白功能中的作用

• 批准号: 8434430
• 负责人: JANA L VOGT
• 金额: $ 30.36万
• 依托单位: DUQUESNE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-01 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8434430
• 关键词: Address; Affect; Biochemical; Cell Survival; Cell Wall; Cell membrane; Cell physiology; Cells; Defect; Development; Diabetes Mellitus; Disease; Environment; Enzymes; Exhibits; Glucans; Glucocorticoids; Growth; Homeostasis; Homologous Gene; Human; In Vitro; Lecithin; Lipids; Liposomes; Lysophospholipase; Malignant Neoplasms; Mammalian Cell; Mediating; Membrane; Membrane Lipids; Membrane Proteins; Metabolic; Metabolic syndrome; Metabolism; Microscopic; Modeling; Molecular Genetics; Obesity; Performance; Phospholipase; Phospholipids; Phosphotransferases; Play; Process; Proteins; Research Personnel; Role; Serum; Sphingolipids; System; Techniques; Testing; Vesicle; Yeasts; deacylation; enzyme activity; glucan synthase; glycerylphosphoinositol; graduate student; in vitro activity; in vivo; interest; mutant; novel; overexpression; permease; physical property; protein function; proteoliposomes; public health relevance; reconstitution; research study; response; undergraduate student; yeast protein

DESCRIPTION (provided by applicant): Membrane homeostasis is a fundamental aspect of cell function and requires the coordinated control of multiple metabolic activities, including biosynthetic enzymes involved in lipid synthesis and phospholipases involved in lipid turnover. Defects in lipid homeostasis can contribute to the development of many diseases, including obesity, diabetes, and cancer. In preliminary results presented here, we have identified Ypk1, the yeast homolog of the human serum and glucocorticoid-induced kinase (SGK1), as a novel regulator of phosphatidylcholine (PC) turnover at the plasma membrane (PM). Importantly, human SGK1 rescues growth defects associated with a ypk1 mutant, indicating functional conservation between the human and yeast proteins. A ypk1 yeast mutant exhibits increased Plb1-mediated PC deacylation at the PM. Furthermore, the accelerated Plb1 activity that occurs in a ypk1 mutant is a compensatory mechanism for cell survival, as a ypk1plb1 double mutant exhibits an increased growth defect and increased sensitivity to the cell wall perturbing agent, calcofluor, as compared to the ypk1 mutant. Because PC is an abundant phospholipid, alterations in its metabolism might be expected to affect the composition and physical properties of the membrane, and, therefore, membrane proteins that reside within. Indeed, we have identified two PM proteins whose activities are compromised by loss of Ypk1 or Plb1. Our central hypothesis is that deletion of YPK1 or PLB1 alters PM lipid composition, which, in turn, impinges upon the activity of integral PM proteins and results in growth defects. In the studies proposed here, we will delineate the process by which Ypk1 and Plb1 modulate integral PM protein activity, including examining the role that Plb1 and Ypk1 play in controlling PM lipid composition. In addition, the lipid requirements of a PM permease whose activity is reduced in response to loss of Ypk1 or Plb1 will be examined using unilamellar lipid vesicles.

描述（由申请人提供）：膜稳态是细胞功能的一个基本方面，需要对多种代谢活性进行协调控制，包括参与脂质合成的生物合成酶和涉及脂质更换的磷脂酶。脂质稳态的缺陷会导致许多疾病的发展，包括肥胖，糖尿病和癌症。在此处介绍的初步结果中，我们确定了YPK1，这是人血清和糖皮质激素诱导的激酶（SGK1）的酵母同源物，是plasmamembrane（PM）的磷脂酰胆碱（PC）周转的新型调节剂。重要的是，人类SGK1挽救了与YPK1突变体相关的生长缺陷，表明人与酵母菌蛋白之间的功能保护。 YPK1酵母突变体在PM处表现出增加的PLB1介导的PC脱酰化。此外，在YPK1突变体中发生的加速PLB1活性是细胞存活的补偿机制，因为与YPK1突变体相比，YPK1PLB1双突变体表现出增加的生长缺陷和对细胞壁扰动剂的敏感性。由于PC是一种丰富的磷脂，因此可能期望其代谢的改变会影响膜的组成和物理特性，因此会影响驻留在其中的膜蛋白。确实，我们已经确定了两种PM蛋白，其活性因YPK1或PLB1的损失而损害。我们的中心假设是YPK1或PLB1的缺失改变了PM脂质组成，这反过来又影响了整合性PM蛋白的活性并导致生长缺陷。在此处提出的研究中，我们将描述YPK1和PLB1调节积分PM蛋白活性的过程，包括研究PLB1和YPK1在控制PM脂质组成中所起的作用。此外，将使用Unilamellar脂质囊泡检查PM渗透酶的脂质需求，该PM渗透酶的活性会降低。