Validation of ALDH1A1 as a target for the treatment of obesity: effects of ALDH1A1 inhibition on energy metabolism

项目摘要 我们的长期目标是开发安全有效的药物来治疗肥胖。我们建议确认ALDH1A1为 通过测试这种酶的新型抑制剂的抗肥胖功效， N42是我们组最近开发的。维甲酸（RA）是维生素A的代谢产物，由以下物质合成： 三种醛脱氢酶ALDH1A1、ALDH1A2和ALDH1A3，它们在时间上表达， 空间上不同，但有时重叠的模式，在组织和发育阶段依赖的方式。 ALDH1A1是两种重要的代谢组织（肝脏和脂肪）中的主要RA合成酶，其中RA 已知其调节参与葡萄糖和脂质代谢以及脂肪组织的基因的表达 分化Aldh1a1-/-小鼠发育正常，健康，有生育能力，并且也受到保护， 导致饮食性肥胖与Aldh1a1-/-小鼠的观察结果一致，我们证明， 用ALDH1A酶的泛抑制剂WIN 18，446治疗的小鼠， 脂肪组织质量，证明了使用ALDH1A的药理学抑制剂治疗肥胖症的可行性。 尽管WIN 18，446治疗有希望抑制体重，但它抑制其他RA合成酶， 以及ALDH2，导致不必要的副作用，如可逆的精子生成抑制和酒精 不容忍因此，我们开发了特异性抑制ALDH1A1的化合物，现在提出 评估一种新型ALDH1A1特异性抑制剂N42治疗以下疾病的疗效和潜在毒性： 肥胖，并确定ALDH1A1调节体重增加的机制， 对ALDH1A1损失的基因表达和代谢物变化的全面研究。在 目的1，我们将确定N42治疗是否可以（1）抑制肥胖小鼠的体重增加， 喂食高脂肪饮食和（2）当向肥胖小鼠提供低热量饮食时，加速它们的体重减轻。我们 还将研究N42治疗的潜在器官毒性，使用标准的，完善的临床试验方案。 和毒理病理学。与ALDH1A1丢失相关的代谢变化（N42处理或Aldh1a1-/-小鼠） 将使用全球代谢组学和基因表达研究进行全面研究。表型 包括代谢物、基因表达、类维生素A水平等的参数将与N42介导的 有效性，以鉴定该化合物未来临床使用的潜在生物标志物。在目标2中，ALDH1A1的作用 将使用组织特异性Aldh1a1-/-小鼠进一步探索肝脏和脂肪组织中的细胞毒性。我们还将确定 成人ALDH1A1缺失如何改变脂肪细胞谱系小鼠的脂肪生成和脂肪细胞肥大 模型最后，我们将通过结合一种新的灌注方法来识别ALDH1A1的组织自主功能。 方法、代谢组学和系统生物学方法。成功完成拟议的研究将 验证ALDH1A1作为治疗肥胖症的新靶点，并提供潜在的原型药物。

PROJECT SUMMARY Our long-term goal is to develop safe and effective drugs to treat obesity. We propose to validate ALDH1A1 as a new drug target for obesity treatment by testing the anti-obesity efficacy of a novel inhibitor of this enzyme, N42, that was recently developed by our group. Retinoic acid (RA), a metabolite of vitamin A, is synthesized by three aldehyde dehydrogenases, ALDH1A1, ALDH1A2, and ALDH1A3, that are expressed in temporally and spatially distinct yet sometimes overlapping patterns in a tissue- and developmental stage-dependent manner. ALDH1A1 is the major RA synthesis enzyme in two metabolically important tissues, liver and adipose, where RA is known to regulate expression of genes involved in glucose and lipid metabolism and adipose tissue differentiation. Aldh1a1-/- mice develop normally, are healthy and fertile, and are also protected from developing diet-induced obesity. In agreement with observations in Aldh1a1-/- mice, we demonstrated that mice treated with WIN 18,446, a pan-inhibitor of ALDH1A enzymes, had lower weight gain due to a decrease in adipose tissue mass, demonstrating the feasibility of using pharmacological inhibitors of ALDH1A to treat obesity. Although WIN 18,446 treatment is promising for weight suppression, it inhibits other RA synthesis enzymes as well as ALDH2, causing unwanted side effects such as reversible spermatogenesis inhibition and alcohol intolerance. Therefore, we developed compounds that specifically inhibit ALDH1A1 and now propose to evaluate the efficacy and potential toxicity of a novel ALDH1A1-specific inhibitor, N42, for treatment of obesity and to determine mechanisms by which ALDH1A1 regulates weight gain by using comprehensive studies of gene expression and metabolite changes in response to ALDH1A1 loss. In Aim 1, we will determine if N42 treatment can (1) suppress weight gain in obese mice when they are continuously fed a high fat diet and (2) accelerate weight loss in obese mice when they are provided reduced calorie diet. We will also investigate potential organ toxicity of N42 treatment using standard, well-established protocols of clinical and toxicologic pathology. Metabolic changes associated with ALDH1A1 loss (N42 treatment or Aldh1a1-/- mice) will be comprehensively investigated using global metabolomics and gene expression studies. Phenotypic parameters including metabolites, gene expression, retinoid levels etc. will be associated with N42-mediated efficacy to identify potential biomarkers for future clinical use of this compound. In Aim 2, the role of ALDH1A1 in liver and adipose tissues will be further explored using tissue-specific Aldh1a1-/- mice. We will also determine how ALDH1A1 loss in adults alters adipogenesis and adipocyte hypertrophy using an adipocyte linage mouse model. Finally, we will identify tissue-autonomous functions of ALDH1A1 by combining a novel perifusion method, metabolomics, and systems-biology approaches. Successful completion of the proposed studies will validate ALDH1A1 as a novel target to treat obesity and provide a potential prototype drug.