Nuclear Lipids in Steroidogenesis

类固醇生成中的核脂质

• 批准号: 8448778
• 负责人: Marion B. Sewer
• 金额: $ 24.77万
• 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/8448778
• 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.

描述（由申请人提供）：类固醇激素是各种生理过程的关键调节剂，包括钠稳态，繁殖以及次要性特征的发展。这些分子允许组织通过作为核和质膜受体的配体起作用，以协调的方式对内部和外部环境的变化做出反应。由于类固醇激素控制了几乎所有细胞类型中许多基因的表达，因此类固醇生成细胞利用多种机制，可确保严格控制这些分子的合成。我们研究的主要目的是了解垂体衍生的激素肾上腺皮质激素（ACTH）通过肾上腺皮质调节皮质醇的生产的机制。我们的研究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鞘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将定义核鞘脂和磷脂代谢的能力。初步数据已经确定，生物活性磷脂和鞘脂通过用作核受体类固醇生成因子1（SF-1）的配体来控制类固醇基因转录。由于主要位于核中，我们假设局部合成的生物活性脂质是控制SF-1功能的关键。脂质分析将用于对核中鞘脂和磷脂种的浓度进行全面和定量评估，以及ACTH对这些脂质量的影响。具体目标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）的三种神经酶之一。我们有证据支持ASAH1B和SF-1之间直接相互作用的作用，并通过磷酸化调节ASAH1功能。我们将研究该酶作为SF-1核调节蛋白的作用。特定的目标3将定义cAMP信号传导激活促进类固醇基因表达的激活的机制。类固醇基因表达增加的是与SF-1的结合激动剂配体（磷脂酸）以及随后的转录激活发生。串联质谱和酶测定将用于定义翻译后修饰在控制合成磷脂酸的酶活性中的作用。总而言之，该提案解决了有关当地产生的生物活性脂质基因调节基因调节的机制的主要问题。从这些研究中获得的知识将提供有关核的代谢能力以及生物活性脂质动态通量在控制基因表达中发挥作用的关键作用的宝贵信息。