Congenital Adrenal Hyperplasia: Calcium Channels as Therapeutic Targets

先天性肾上腺增生：钙通道作为治疗靶点

• 批准号: 7178483
• 负责人: KAREN J LOECHNER
• 金额: $ 12.52万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7178483
• 关键词: Accounting; Adrenal Gland Diseases; Adrenal gland hypofunction; Adrenal hormone preparation; Adult; Amlodipine; Androgen Analogues; Androgens; Anterior Pituitary Gland; Antibodies; Attenuated; Basic Science; Binding; Biological Assay; Bone Density; CRH gene; Calcium; Calcium Channel; Calcium Signaling; Cell Line; Cells; Child; Chimeric Proteins; Clinical; Clinical Research; Clinical Trials; Complement; Complex; Condition; Confocal Microscopy; Congenital adrenal hyperplasia; Corticotropin; Corticotropin-Releasing Hormone; Coupled; Coupling; Cross-Over Studies; Cytoplasmic Granules; DEXA; Defect; Dihydropyridines; Disease; Dominant-Negative Mutation; Dose; Double-Blind Method; Endocrine; Feedback; Genitalia; Glucocorticoids; Glucose Intolerance; Goals; Growth; High voltage activated calcium channel; Hormonal; Hour; Hydrocortisone; Immunofluorescence Immunologic; In Vitro; L-Type Calcium Channels; Label; Life; Liquid Chromatography; Long-Term Effects; Mentorship; Molecular; Neurons; Neuropeptides; Neurosecretory Systems; Obesity; Pathway interactions; Pattern; Peptides; Phase; Pituitary Gland; Placebo Control; Placebos; Pregnanetriol; Preparation; Production; Property; Protein Isoforms; Proteins; SNAP receptor; Serum; Shunt Device; Site; Spectrophotometry; Steroids; Stigmata; Synapses; Testing; Time; Translating; Treatment Protocols; Urine; Virilism; Work; attenuation; bone metabolism; bone turnover; dihydropyridine; hypothalamic-pituitary-adrenal axis; immunocytochemistry; improved; in vivo; novel; response; social stigma; therapeutic target; voltage

DESCRIPTION (provided by applicant): This K08 application under the co-mentorship of Drs. Bob Rosenberg and Gerry Oxford has two goals: 1) to understand the cellular mechanisms that underlie coupling of voltage-activated calcium channels to regulated peptide secretion in the anterior pituitary, and 2) to assess the clinical impact of targeted calcium channel blockade in Congenital Adrenal Hyperplasia (CAH), a disorder resulting from pituitary hypersecretion. In studies of a pituitary corticotroph cell line (AtT-20) I identified three distinct high voltage-activated calcium channels that are expressed in similar abundance. Despite this, only the L-type [dihydropyridine (DHP)-sensitive] channel is capable of triggering calcium-dependent secretion of ACTH. The primary focus of this proposal, therefore, is to examine the mechanisms that underlie the coupling of DHP-sensitive channels to ACTH release. I hypothesize that differential localization of the L-type channels accounts for the distinct function of the neurosecretory apparatus in ACTH-secreting cells. I propose to: a) examine the cellular sites of calcium channels and synaptic components using immunocytochemistry/ confocal microscopy, and b) disrupt coupling using a dominant-negative approach. In CAH, the most common adrenal disorder in children, a molecular defect in cortisol production removes normal negative feedback to the anterior pituitary and results in elevated ACTH secretion. Elevated ACTH further increases cortisol precursors, and shunts these steroid intermediates to androgen synthetic pathways. The clinical stigmata (e.g., ambiguous genitalia, virilization and short stature in adults) are due to the excess in androgens. Treatment requires life-long glucocorticoid replacement to restore the normal feedback mechanism. Determining the "optimal level" ofglucocorticoid replacement, however, is difficult: under-treatment leads to adrenal insufficiency and androgen excess; over-treatment leads to glucocorticoid excess (e.g., obesity, glucose intolerance and osteopenia). My work with the pituitary cells in culture suggests that selective pharmacologic blockade of L-type (DHP-sensitive) channels, and, in turn, attenuation of ACTH release, will provide a novel adjunct therapy by allowing lower glucocorticoid dosing. This would result in enhanced linear growth and improved bone mineral density. These basic research and clinical studies complement one another, and together, they should enhance our understanding of the cellular mechanisms underlying peptide secretion. Furthermore, they may allow for improved treatment in hypersecretory conditions, such as CAH.

描述（由申请人提供）： Bob Rosenberg和Gerry Oxford博士共同指导的K 08申请有两个目标：1）了解电压激活钙通道与垂体前叶中调节肽分泌偶联的细胞机制，以及2）评估靶向钙通道阻滞剂对先天性肾上腺增生（CAH）的临床影响，CAH是一种由垂体分泌过多引起的疾病。在垂体促肾上腺皮质激素细胞系（AtT-20）的研究中，我确定了三种不同的高电压激活的钙通道，它们以相似的丰度表达。尽管如此，只有L型[二氢吡啶（DHP）敏感]通道能够触发ACTH的钙依赖性分泌。因此，本提案的主要重点是研究DHP敏感通道与ACTH释放耦合的机制。我推测，差异定位的L-型通道占ACTH分泌细胞的神经分泌装置的独特功能。我提议：a）使用免疫细胞化学/共聚焦显微镜检查钙通道和突触组分的细胞位点，和B）使用显性负性方法破坏偶联。在CAH中，最常见的儿童肾上腺疾病，皮质醇产生的分子缺陷消除了对垂体前叶的正常负反馈，导致ACTH分泌增加。升高的ACTH进一步增加皮质醇前体，并将这些类固醇中间体分流到雄激素合成途径。临床上的污点（例如，生殖器模糊、男性化和成年人身材矮小）是由于雄激素过量。治疗需要终身糖皮质激素替代，以恢复正常的反馈机制。然而，确定糖皮质激素替代的“最佳水平”是困难的：治疗不足导致肾上腺功能不全和雄激素过多;过度治疗导致糖皮质激素过量（例如，肥胖、葡萄糖耐受不良和骨质减少）。我对培养的垂体细胞的研究表明，选择性药物阻断L型（DHP敏感）通道，进而减弱ACTH的释放，将通过降低糖皮质激素的剂量提供一种新的辅助治疗。这将导致增强的线性生长和改善的骨矿物质密度。这些基础研究和临床研究相互补充，共同提高了我们对肽分泌细胞机制的理解。此外，它们可以允许在高分泌病症（例如CAH）中改善治疗。