Animal Genome and Gene Function Laboratory, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, PR China.
College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, PR China.
J Steroid Biochem Mol Biol. 2021 May;209:105833. doi: 10.1016/j.jsbmb.2021.105833. Epub 2021 Jan 29.
Given the intensive selection for increased milk production, it is imperative that the problem of declining fertility in dairy cows be reversed. In female mammals their reproductive traits and functioning is controlled by a finely tuned process balancing estrogens and androgens, in which androgens (e.g., testosterone) as a precursor substance can participate in estrogen synthesis by activating 17β-hydroxysteroid dehydrogenase (17betaHSD). Being a key catalyst for testosterone synthesis, we hypothesized HSD17B3 gene is involved in the ovary's development and thereby capable of influencing cows' fecundity. Herein, to investigate the relationship between polymorphisms of the HSD17B3 gene and cow fertility, we characterized three insertion/deletion (indels) polymorphisms of this gene in 1110 healthy bovine ovaries. Their respective minimum allelic frequency (MAF) ranged from 0.180 to 0.482. For the ovary morphological traits, correlations revealed that both P1-D and P4-D demonstrated significant associations with ovarian height (P = 0.007 and 0.004, respectively), while P5-I was found to be significantly associated with the ovarian weight (P = 0.024). For ovarian volume, a significant correlation was uncovered between it and both polymorphisms of P4-D (P = 0.036) and P5-I (P = 0.045). Cows with either the DD genotype of P4-D or P5-I tended to have greater ovarian volume, a result consistent with their relationship to ovarian weight (P5-I) or height (P4-D). For the mature follicle traits, polymorphisms of P4-D were found significantly associated with the number of mature follicles (P = 0.045). Furthermore, expression levels of HSD17B3 differed significantly between the maximal and minimum groups of ovarian weight or volume, and the transcription factors GATA-1 and USF were predicted to bind P1-D and P4-D, respectively. This suggested the detected intron mutations could affect HSD17B3's transcription by regulating the binding of transcription factors, thereby affecting ovarian weight and other reproductive traits. As a potential effective molecular marker loci significantly related to traits of ovary and follicle, these three indels could be used in practical molecular marker-assisted selection (MAS) breeding programs, to optimize female fertility and enhance economic efficiency in the dairy cow industry.
鉴于对增加牛奶产量的强烈选择，扭转奶牛生育率下降的问题势在必行。在雌性哺乳动物中，其生殖特征和功能受雌激素和雄激素精细平衡过程的控制，其中雄激素（如睾酮）作为前体物质可以通过激活 17β-羟类固醇脱氢酶（17βHSD）参与雌激素合成。作为睾酮合成的关键催化剂，我们假设 HSD17B3 基因参与卵巢的发育，从而能够影响奶牛的繁殖力。在此，为了研究 HSD17B3 基因多态性与牛繁殖力的关系，我们在 1110 个健康牛卵巢中对该基因的三个插入/缺失（indels）多态性进行了特征描述。它们各自的最小等位基因频率（MAF）范围为 0.180 至 0.482。对于卵巢形态特征，相关性表明 P1-D 和 P4-D 均与卵巢高度呈显著相关（P=0.007 和 0.004），而 P5-I 与卵巢重量呈显著相关（P=0.024）。对于卵巢体积，发现它与 P4-D 和 P5-I 的两个多态性之间存在显著相关性（P=0.036 和 0.045）。具有 P4-D 或 P5-I 的 DD 基因型的奶牛往往具有更大的卵巢体积，这与它们与卵巢重量（P5-I）或高度（P4-D）的关系一致。对于成熟卵泡特征，P4-D 的多态性与成熟卵泡数量显著相关（P=0.045）。此外，HSD17B3 的表达水平在卵巢重量或体积的最大和最小组之间存在显著差异，预测转录因子 GATA-1 和 USF 分别与 P1-D 和 P4-D 结合。这表明检测到的内含子突变可能通过调节转录因子的结合来影响 HSD17B3 的转录，从而影响卵巢重量和其他生殖特征。作为与卵巢和卵泡特征显著相关的潜在有效分子标记基因座，这三个 indels 可以用于实际的分子标记辅助选择（MAS）育种计划，以优化奶牛的繁殖力并提高奶牛业的经济效益。
