Retinoid receptor antagonists as novel male contraceptives

描述(由申请人提供)：这些研究的主要目标是了解维甲酸信号在精子发生调节中的作用，并利用其基本功能的抑制作为一种新的男性避孕方法。全反式维甲酸(ATRA)是维生素A的活性代谢物，其功能至少部分是通过与类固醇激素超家族的核受体--维甲酸受体(RAR)结合来实现的。ATRA信号的重要性，特别是通过RARA受体在小鼠中的基因打靶已经被证明：RARA缺陷的雄性小鼠是不育的，精子发生的缺陷类似于维生素A缺乏(VAD)的动物。根据先前对使用PAN-RAR拮抗剂BMS-189453治疗的动物的“睾丸毒性”的观察，我们现在已经表明，确实，精子发生受到抑制，而且这种诱导的不育是可逆的。这表明，BMS-189453具有作为一种新的、非类固醇激素为基础的男性避孕方法的潜力。本提案特别关注使用RAR泛拮抗剂BMS-189453在小鼠模型中抑制体内精子发生。提出了三个综合目标，范围从解决与剂量水平和剂量长度有关的非常实用的问题以最大化疗效，到阐明药物作用的细胞和分子靶点。第一个具体目标将是：一)延长治疗时间，以确定抑制精子发生的最长时间，之后可以恢复正常的精子生成；二)评估即使比我们初步实验中使用的剂量更低的药物是否也能有效地抑制精子发生；三)确定仍然有效的最佳剂量的范围，以便标准化给药方案；以及四)检查恢复生育能力后产生的后代的正常生长。VAD，用泛拮抗剂BMS-189453治疗，以及缺乏特异性的RARA受体，都会导致精子细胞排列和受精的缺陷。特定的目标2将确定视黄醇信号的细胞靶点，以及在没有视黄醇信号的情况下，它们是如何被干扰而导致这些特征性异常的。最后，Aim 3将利用微阵列分析，通过识别那些表达因抑制所有三个RARs而改变的基因，与仅缺乏RARA的睾丸和正常小鼠的变化相比较，来检验BMS-189453的至少部分影响是在转录水平上中介的假设。 公共相关性：拟议的研究将提供关于维甲酸拮抗剂作为男性避孕新方法的潜在用途的关键信息。这些实验将提供有关给药方案的数据，以最大限度地提高疗效，同时最大限度地减少化合物暴露，同时确保可逆性。男性避孕的非荷尔蒙策略将为渴望替代计划生育方法的夫妇和世界各地人口过多的国家提供健康益处。

DESCRIPTION (provided by applicant): The overarching goal of these studies is to understand the role of retinoid signaling in the regulation of spermatogenesis and to exploit the inhibition of its essential function as a new and novel approach to male contraception. All trans retinoic acid (ATRA) is an active metabolite of vitamin A and exerts its function at least in part by binding to nuclear receptors of the steroid hormone superfamily, the retinoic acid receptors (RARs). The importance of ATRA signaling via the RARa receptor in particular has been demonstrated by gene targeting in mice: RARa-deficient male mice are sterile with defects in spermatogenesis similar to those seen in vitamin A-deficient (VAD) animals. Following up on previous observations of 'testicular toxicity' in animals treated with the pan-RAR antagonist BMS-189453, we have now shown that indeed, spermatogenesis is inhibited, and further, that this induced sterility is reversible. This suggested that BMS-189453 had potential as a novel, non-steroid hormone-based approach to male contraception. The present proposal focuses specifically on the use of the RAR pan-antagonist BMS-189453 to inhibit spermatogenesis in vivo in the mouse model. Three integrated Aims are proposed, which range in scope from addressing very applied questions with regard to levels and length of dosing to maximize efficacy to elucidating the cellular and molecular targets of the drug's action. The first Specific Aim will i) extend the duration of treatment to determine the maximum period of inhibition of spermatogenesis after which normal spermatogenesis can be restored; ii) assess whether even lower doses of the drug than used in our preliminary experiments can be effective in inhibiting spermatogenesis; iii) determine the range above and below the optimal dose that is still effective in order to standardize the dosing regimen; and iv) examine the progeny that result after the restoration of fertility for their normal growth. VAD, treatment with the pan-antagonist BMS-189453, and lack of the RARa receptor specifically all result in defects in spermatid alignment and spermiation. Specific Aim 2 will determine the cellular targets of retinoid signaling and how are they disrupted in its absence to result in these characteristic abnormalities. Finally, Aim 3 will test the hypothesis that at least some of the effects of BMS-189453 are mediated at the transcriptional level by identifying those genes whose expression is altered by inhibition of all three RARs, as compared to the changes seen in testes lacking only RARa and to normal mice, using microarray analysis. PUBLIC RELEVANCE: The proposed studies will provide critical information on the potential use of retinoid antagonists as a new and novel approach to male contraception. The experiments will provide data on dosing regimens to maximize efficacy while minimizing compound exposure, all the while ensuring reversibility. Non-hormonal strategies for male contraception would provide health benefits to couples desiring alternative family planning approaches and to over-populated countries world-wide.