Nuclear Lipids in Steroidogenesis

类固醇生成中的核脂质

• 批准号: 8248320
• 负责人: Marion B. Sewer
• 金额: $ 26.5万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-24 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8248320
• 关键词: Address; Adrenal Cortex; Adrenal Glands; Agonist; Anabolism; Androgens; Binding; Biochemical; Biological Assay; CYP17A1 gene; Catabolism; Cell Nucleus; Cell membrane; Cells; Ceramidase; Chromatin; Complex; Corticotropin; Cyclic AMP; Data; Development; Diacylglycerol Kinase; Dissociation; Endocrine System Diseases; Ensure; Environment; Enzymes; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Goals; Homeostasis; Hormones; Human; Hydrocortisone; Knowledge; Ligand Binding; Ligands; Lipids; Mediating; Metabolic; Metabolism; Microscopic; Molecular; Nuclear; Nuclear Envelope; Nuclear Receptors; Phosphatidic Acid; Phospholipid Metabolism; Phospholipids; Phosphorylation; Physiological Processes; Pituitary Gland; Pituitary-dependent Cushing' s disease; Play; Polycystic Ovary Syndrome; Post-Translational Protein Processing; Process; Production; Property; Proteins; RNA Processing; Receptor Activation; Regulation; Reproduction; Research; Role; SF1; Sex Characteristics; Signal Pathway; Signal Transduction; Site-Directed Mutagenesis; Sodium; Sphingolipids; Sphingosine; Steroid biosynthesis; Sum; Testing; Tissues; Transactivation; Transcriptional Activation; Work; adrenal hyperplasia; base; cell type; chromatin immunoprecipitation; enzyme activity; galactosylgalactosylglucosylceramidase; insight; mRNA Export; novel; peptide hormone; protein protein interaction; public health relevance; receptor; receptor function; research study; response; sphingosine 1-phosphate; steroid hormone; steroid hormone biosynthesis; tandem mass spectrometry

DESCRIPTION (provided by applicant): Steroid hormones are key regulators of a diverse array of physiological processes, including sodium homeostasis, reproduction, and the development of secondary sex characteristics. These molecules allow tissues to respond in a coordinated manner to changes in the internal and external environments by functioning as ligands for both nuclear and plasma membrane receptors. Because steroid hormones control the expression of numerous genes in virtually all cell types, steroidogenic cells utilize multiple mechanisms that ensure tight control of the synthesis of these molecules. A major goal of our research is to understand the mechanisms by which the pituitary-derived hormone adrenocorticotropin (ACTH) regulates cortisol production by the adrenal cortex. Our research has identified a key role for bioactive sphingolipids and phospholipids. These molecules control hormone production by controlling the transcription of steroidogenic genes. We hypothesize that ACTH controls steroid hormone biosynthesis by modulating the availability of bioactive sphingolipids and phospholipids in the nuclei of adrenocortical cells. Specific Aim 1 will define the capacity for nuclear sphingolipid and phospholipid metabolism. Preliminary data has established that bioactive phospholipids and sphingolipids control steroidogenic gene transcription by serving as ligands for the nuclear receptor steroidogenic factor-1 (SF-1). Since is primarily localized in the nucleus, we hypothesize that locally synthesized bioactive lipids are key for controlling SF-1 function. Lipid profiling will be used to gain a comprehensive and quantitative assessment of the concentrations of sphingolipid and phospholipid species in the nucleus and the effect of ACTH on the amounts of these lipids. Specific Aim 2 determine the mechanism by which acid ceramidase (encoded by ASAH1b) regulates nuclear SPH concentrations and SF-1 function. ASAH1b is one of three ceramidases that produces sphingosine (SPH). We have evidence to support a role for direct interaction between ASAH1b and SF-1 and for the regulation of ASAH1 function by phosphorylation. We will investigate the role of this enzyme as a SF-1 coregulatory protein. Specific Aim 3 will define the mechanism by which activation of cAMP signaling promotes ligand (PA)-dependent activation of steroidogenic gene expression. Increased steroidogenic gene expression occurs with the binding agonist ligand (phosphatidic acid) to SF-1 and the subsequent activation of transcription. Tandem mass spectrometry and enzymatic assays will be used to define the role of posttranslational modification in controlling the activity of enzymes that synthesize phosphatidic acid. In sum this proposal addresses major questions about the mechanisms underlying gene regulation by locally produced bioactive lipids. The knowledge gained from these studies will provide valuable information about the metabolic capacity of the nucleus and the key role that dynamic flux of bioactive lipids plays in the control of gene expression. PUBLIC HEALTH RELEVANCE: Relevance Understanding how genes are regulated in cells that make steroid hormones will provide insight into the mechanisms by which pathophysiological concentrations of cortisol and adrenal androgens are produced. This work will provide insight into multiple endocrine disorders, including adrenal hyperplasia, polycystic ovary syndrome, and Cushing's disease.

描述(由申请人提供)：类固醇激素是一系列不同生理过程的关键调节器，包括钠稳态、生殖和第二性征的发展。这些分子通过充当核受体和质膜受体的配体，使组织能够以协调的方式对内外环境的变化做出反应。由于类固醇激素控制着几乎所有细胞类型中许多基因的表达，类固醇生成细胞利用多种机制确保严格控制这些分子的合成。我们研究的一个主要目标是了解垂体衍生激素促肾上腺皮质激素(ACTH)调节肾上腺皮质皮质醇产生的机制。我们的研究已经确定了生物活性鞘脂和磷脂的关键作用。这些分子通过控制类固醇合成基因的转录来控制激素的产生。我们假设ACTH通过调节肾上腺皮质细胞核中生物活性的鞘磷脂和磷脂的可用性来控制类固醇激素的生物合成。具体目标1将确定核鞘磷脂和磷脂代谢的能力。初步数据表明，生物活性磷脂和鞘磷脂通过作为核受体类固醇生成因子-1(SF-1)的配体来控制类固醇基因的转录。由于主要定位于细胞核，我们假设局部合成的生物活性脂是控制SF-1功能的关键。脂质图谱将被用来全面和定量地评估神经鞘脂和磷脂在细胞核中的浓度，以及ACTH对这些脂类数量的影响。特定目的2确定酸性神经酰胺酶(由ASAH1b编码)调节核SPH浓度和SF-1功能的机制。ASAH1b是产生鞘氨醇(SPH)的三种神经酰胺酶之一。我们有证据支持ASAH1b和SF-1之间的直接相互作用以及通过磷酸化调节ASAH1功能。我们将研究这种酶作为SF-1共调节蛋白的作用。具体目标3将确定cAMP信号的激活促进类固醇合成基因表达的配体(PA)依赖的激活的机制。随着激动剂配体(磷脂酸)与SF-1结合并随后激活转录，类固醇合成基因表达增加。串联质谱仪和酶分析将被用来确定翻译后修饰在控制合成磷脂酸的酶的活性方面的作用。总而言之，这项建议解决了关于本地生产的生物活性脂类进行基因调控的潜在机制的主要问题。从这些研究中获得的知识将提供关于细胞核代谢能力的有价值的信息，以及生物活性脂的动态流动在基因表达控制中所起的关键作用。 公共卫生相关性：了解基因是如何在制造类固醇激素的细胞中调节的，将有助于深入了解皮质醇和肾上腺雄激素的病理生理浓度产生的机制。这项工作将提供对多种内分泌疾病的洞察，包括肾上腺增生、多囊卵巢综合征和库欣病。