Retinoid Receptor Antagonists as Novel Male Contraceptives

描述(由申请人提供)：多年来，人们已经认识到饮食中的视黄醇(维生素A)和维甲酸信号对睾丸的正常发育和分化的重要性。信号转导部分是通过维甲酸受体(RARs)来实现的，维甲酸受体有三种亚型，α、？和γ。我们和其他人已经证明了通过RARα受体传递信号的重要性，特别是在通过基因打靶的精子发生过程中：RARα缺陷的小鼠(RARA-/-)是存活的，但雄性是不育的，表现出生精上皮的缺陷，类似于看到的VAD饮食。我们还表明，口服生物可用PAN-RAR拮抗剂治疗的小鼠变得不育，具有类似的睾丸异常。我们进一步表明，这种诱导的不孕症是可逆的，即使在日常治疗的时间一样长。 以停药后4个月为准。重要的是，在这些低剂量下没有观察到可检测到的副作用，正常的后代在恢复生育能力后由父亲生育。这表明，RAR拮抗剂具有作为新型非甾体化合物用于男性避孕的潜力。我们建议按照以下具体目标开发这一潜力。具体目的1.鉴于PAN-RAR拮抗剂化合物9已成功地用于诱导男性不育，并认识到RARα是调节精子发生的关键因素，我们建议测试RARα选择性拮抗剂，这些拮抗剂立即可用，并正在由我们的药物化学家合作者开发用于抑制精子发生。特定目的2.RARα作为转录因子发挥作用，激活或抑制下游靶基因，拮抗剂发挥阻断这种转录调控的作用。因此，我们认为这些下游靶基因本身可能是干扰精子发生和诱导不育的靶基因，特别是如果它们是睾丸特异的或以睾丸特异的方式发挥作用的话。由于精子作用似乎是一个对维甲酸信号的调节非常敏感的细胞过程，因此，我们将集中在细胞和分子水平上阐明导致精子细胞相对于基底室的不适当锚定、未能从基底室转移到管腔以及未能脱离受精的机制。这些实验将包括检查已知在这些过程中重要的候选基因的表达，并通过最先进的RNA-Seq分析识别新基因。具体目的3.为了寻求RAR拮抗剂最终在男性中作为避孕药物，我们建议在非人类灵长类动物模型(普通绒猴)中进行一项小规模试验。我们的目标是通过检查拮抗剂在诱导血管紧张素转换酶的作用方面的疗效，为未来的临床前试验奠定基础。 不育和恢复生育能力。这些研究将与圣安东尼奥西南国家灵长类研究中心的科学家合作完成。我们的预测是，泛拮抗剂化合物9将以一种可逆的方式抑制精子发生，剂量不会引起不良副作用。

DESCRIPTION (provided by applicant): The importance of dietary retinol (vitamin A) and retinoid signaling for normal development and differentiation in the testis has been recognized for many years. Signaling is effected in part through the retinoic acid receptors (RARs), of which there are three isoforms, α, ß, and γ. We and others have shown the importance of signaling via the RARα receptor in particular during spermatogenesis by gene targeting: mice deficient in RARα (Rara-/-) are viable but the males are sterile, exhibiting defects in the seminiferous epithelium resembling those seen VAD diet. We have also shown that mice treated with an orally bioavailable pan-RAR antagonist become sterile, with similar testicular abnormalities. We have further shown that this induced sterility is reversible even with daily treatments for as long as 4 months upon cessation of drug treatment. Importantly, no detectable side effects were observed at these low doses and normal progeny were sired by fathers after restoration of fertility. This suggested that RAR-antagonists have potential as novel, non-steroidal compounds for male contraception. We propose to pursue this potential as outlined in the following specific aims. Specific Aim 1. Given the successful use of the pan-RAR antagonist compound 9 to induce male sterility and the recognition that it is RARα that is critical for regulating spermatogenesis, we propose to test RARα-selective antagonists that are immediately available and are being developed by our medicinal chemist collaborators in inhibiting spermatogenesis. Specific Aim 2. RARα functions as a transcription factor, activating or repressing downstream target genes and antagonists function to block this transcriptional regulation. We therefore propose that such downstream target genes may themselves represent targets for interfering with spermatogenesis and inducing sterility, particularly if they are either testis-specific or function in a testisspecific manner. As spermiation appears to be a cellular process that is exquisitely sensitive to modulation of retinoid signaling, we will therefore focus on elucidating the mechanisms responsible for the improper anchorage of spermatids relative to the basal compartment, failure to translocate from basal compartment to the tubular lumen, and failure to disengage for spermiation, etc. at the cellular and molecular levels. These experiments will involve examining the expression of candidate genes known to be important in these processes and the identification of new genes by state-of-the-art RNA-Seq analysis. Specific Aim 3. To pursue RAR-antagonists ultimately as contraceptives in men, we propose to undertake a small scale trial in a non-human primate model (the common marmoset). The goal is to set the stage for future pre-clinical trials by examining the efficacy of antagonists with regard to induction of sterility and restoration of fertility. These studies will be done in collaboration with scientistsat the Southwest National Primate Research Center in San Antonio. Our prediction is that the pan-antagonist compound 9 will inhibit spermatogenesis in a reversible manner at doses that will not induce undesirable side effects.