Tissue-Specific Regulation and Effects of CYP24A1

CYP24A1 的组织特异性调控和作用

基本信息

批准号：
10580931
负责人：
MYLES S WOLF
金额：
$ 54.75万
依托单位：
DUKE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-01-01 至 2027-11-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10580931
关键词：
Address Adenine Animals Attention Attenuated Biological Assay Blood Vessels Bone Diseases CRISPR/Cas technology CYP27B1 gene Calcium Cardiac Cardiovascular Diseases Catabolism Cessation of life Chronic Kidney Failure Complication Data Diet Dihydroxycholecalciferols Disease Ensure Enterocytes Enzymes Fibroblast Growth Factor Receptors Fracture Genes Genetic Health Heart Histology Homeostasis Human Human Genome Hypercalcemia Intestines Intoxication Investigation Kidney Kidney Diseases Knockout Mice Liver Longitudinal Studies Measures Metabolic Metabolic Bone Diseases Minerals Mixed Function Oxygenases Molecular Mus Nephrolithiasis Organ Organoids PTH gene Phenotype Physiological Protein Isoforms Regulation Renal function Research Role Secondary Hyperparathyroidism Serum Signal Pathway Signal Transduction Skeletal Development Structure Surgical Models Syndrome Tamoxifen Testing Tissues Toxic effect Variant Vitamin D Vitamin D3 Receptor Wild Type Mouse bone calcium absorption design fibroblast growth factor 23 genetic approach genome wide association study in vivo indexing inhibitor inorganic phosphate loss of function mutation mouse model nephrotoxicity novel novel therapeutic intervention novel therapeutics synthetic enzyme

项目摘要

PROJECT SUMMARY Normal mineral homeostasis is regulated by the actions of parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and vitaminD on the intestine,kidney andbone. Vitamin D is counter regulatedby PTHand FGF23: PTH increases andFGF23 decreases circulatinglevels of thebiologically active formof vitamin D, 1,25-dihydroxyvitamin D (1,25D), via opposing actions on the 1,25D-synthetic enzyme, CYP27B1 (1α-hydroxylase), and the 1,25D- catabolic enzyme, CYP24A1 (24-hydroxylase). Despite compelling genetic and physiological evidence in humans and animals that point to the critical importance of CYP24A1, most prior research of vitamin D in health and in chronic kidney disease (CKD) focused on 1,25D synthesis by CYP27B1; much less attention has been devoted to 1,25D catabolism by CYP24A1. To advance research of CYP24A1, we developed new lox-P mice that enable tissue-selective and inducible deletion of Cyp24a1. We will use this novel mouse line to test our overarching hypothesis that tissue-specific effects of CYP24A1 in the kidney and intestinecontribute to normal and disordered mineral homeostasis. Since the kidney is the main regulator of circulating 1,25D, we hypothesize that kidney- specific Cyp24a1 deletion will increase serum 1,25D and downstream vitamin D receptor (VDR) activity in all tissues, including the intestine and kidney. In CKD, this will cause hypercalcemia that suppresses PTH, but will further harm kidney function due to 1,25D intoxication. In contrast, since the intestine does not contribute meaningfully to circulating1,25D, we expect intestine-specific Cyp24a1 deletion to increase1,25D and VDR activity only in the intestine. Resultant increases in intestinal calcium absorption will suppress PTH, which will lead to decreased serum 1,25D and thus, decreased VDR activity in the kidney. As a result, we hypothesize that inhibiting intestinal CYP24A1 in CKD will attenuate secondary hyperparathyroidismwithout causing hypercalcemia or further kidney toxicity. In Aim 1, we will investigate the effects of CYP24A1 in normal mineral homeostasis by studying mice with deletion of Cyp24a1 from the kidney (Six2Cre-Cyp24flox), intestine (VillinCreERT2-Cyp24flox) and globally (UBCCreERT2-Cyp24flox). In Aim 2, we will test our hypothesis that inhibiting intestinal CYP24A1 will attenuate secondary hyperparathyroidism and downstream complications of CKD without worsening CKD. In Aims 1 and 2, readouts of effect will include longitudinal physiological measures of mineral homeostasis and kidney function, and expression of VDR target genes in the kidney and intestine; in Aim 2 we will also assess cardiac structure and function, and kidney, bone and vascular histology. In Aim 3, we will define the molecular mechanisms of CYP24A1 regulationin enterocytes usingpharmacological and genetic approaches in mouseand humanintestinal organoids. Readouts of effect will include cell signaling assays and expressionof Cyp24a1 and VDR target genes. By defining the tissue-specific effects and molecular regulation of CYP24A1 using our new mouse models, we will uncover novel therapeutic strategies for CKD and other syndromes of disordered mineral homeostasis.

项目概要正常矿物质稳态受甲状旁腺激素 (PTH)、成纤维细胞生长因子 23 的作用调节 (FGF23) 和维生素 D 对肠道、肾脏和骨骼的作用受 PTH 和 FGF23 的反向调节：PTH。增加和降低 FGF23 生物活性形式维生素 D（1,25-二羟基维生素）的循环水平 D (1,25D)，通过对 1,25D-合成酶、CYP27B1（1α-羟化酶）和 1,25D- 的相反作用尽管在人类中有令人信服的遗传和生理证据，但分解代谢酶 CYP24A1（24-羟化酶）。和动物指出了 CYP24A1 的至关重要性，大多数先前的维生素 D 在健康和疾病方面的研究慢性肾脏病 (CKD) 的重点是 CYP27B1 的 1,25D 合成，但很少有人关注这一点； CYP24A1 的 1,25D 分解代谢为了推进 CYP24A1 的研究，我们开发了新的 lox-P 小鼠。我们将使用这种新型小鼠品系来测试我们的总体情况。假设 CYP24A1 在肾脏和肠道中的组织特异性作用有助于正常和紊乱由于肾脏是循环 1,25D 的主要调节器，因此我们认为肾脏- 特定的 Cyp24a1 缺失将增加所有患者的血清 1,25D 和下游维生素 D 受体 (VDR) 活性在 CKD 中，这会导致抑制 PTH 的高钙血症，但会抑制 PTH 的生长。相比之下，1,25D 中毒会进一步损害肾功能，因为肠道不会做出贡献。对循环1,25D有意义，我们预计肠道特异性Cyp24a1缺失会增加1,25D和VDR活性仅在肠道中，肠道钙吸收的增加会抑制 PTH，从而导致 PTH 升高。血清 1,25D 水平降低，从而降低肾脏中的 VDR 活性。 CKD 中的肠道 CYP24A1 将减轻继发性甲状旁腺功能亢进症，而不会引起高钙血症或进一步在目标 1 中，我们将通过研究 CYP24A1 对正常矿物质稳态的影响。从肾脏 (Six2Cre-Cyp24flox)、肠道 (VillinCreERT2-Cyp24flox) 和全身删除 Cyp24a1 的小鼠 (UBCCreERT2-Cyp24flox) 在目标 2 中，我们将测试抑制肠道 CYP24A1 会减弱的假设。在目标 1 和 2 中，继发性甲状旁腺功能亢进症和 CKD 下游并发症。效果读数将包括矿物质稳态和肾功能的纵向生理测量，以及 VDR 靶基因在肾脏和肠道中的表达；在目标 2 中，我们还将评估心脏结构和在目标 3 中，我们将定义 CYP24A1 的分子机制。在小鼠和人类肠道类器官中使用药理学和遗传学方法调节肠细胞。通过定义，效果读数将包括细胞信号转导测定以及 Cyp24a1 和 VDR 靶基因的表达。使用我们的新小鼠模型，我们将揭示 CYP24A1 的组织特异性效应和分子调控慢性肾病和其他矿物质稳态紊乱综合征的新治疗策略。