Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA.
J Biol Chem. 2012 Jul 20;287(30):25173-90. doi: 10.1074/jbc.M112.362053. Epub 2012 Jun 4.
DROSHA is a nuclear RNase III enzyme responsible for cleaving primary microRNAs (miRNAs) into precursor miRNAs and thus is essential for the biogenesis of canonical miRNAs. DICER is a cytoplasmic RNase III enzyme that not only cleaves precursor miRNAs to produce mature miRNAs but also dissects naturally formed/synthetic double-stranded RNAs to generate small interfering RNAs (siRNAs). To investigate the role of canonical miRNA and/or endogenous siRNA production in spermatogenesis, we generated Drosha or Dicer conditional knock-out (cKO) mouse lines by inactivating Drosha or Dicer exclusively in spermatogenic cells in postnatal testes using the Cre-loxp strategy. Both Drosha and Dicer cKO males were infertile due to disrupted spermatogenesis characterized by depletion of spermatocytes and spermatids leading to oligoteratozoospermia or azoospermia. The developmental course of spermatogenic disruptions was similar at morphological levels between Drosha and Dicer cKO males, but Drosha cKO testes appeared to be more severe in spermatogenic disruptions than Dicer cKO testes. Microarray analyses revealed transcriptomic differences between Drosha- and Dicer-null pachytene spermatocytes or round spermatids. Although levels of sex-linked mRNAs were mildly elevated, meiotic sex chromosome inactivation appeared to have occurred normally. Our data demonstrate that unlike DICER, which is required for the biogenesis of several small RNA species, DROSHA is essential mainly for the canonical miRNA production, and DROSHA-mediated miRNA production is essential for normal spermatogenesis and male fertility.
DROSHA 是一种核 RNase III 酶，负责将初级 microRNAs（miRNAs）切割成前体 miRNAs，因此对于经典 miRNAs 的生物发生至关重要。DICER 是一种细胞质 RNase III 酶，不仅可以切割前体 miRNAs 以产生成熟 miRNAs，还可以切割天然形成/合成的双链 RNA 以产生小干扰 RNA（siRNA）。为了研究经典 miRNA 和/或内源性 siRNA 产生在精子发生中的作用，我们使用 Cre-loxp 策略在生后睾丸中的生殖细胞中特异性失活 Drosha 或 Dicer，从而生成 Drosha 或 Dicer 条件性敲除（cKO）小鼠品系。由于精母细胞和精子细胞耗竭导致少精症或无精症，Drosha 和 Dicer cKO 雄性均不育。生殖细胞破坏的发育过程在形态学水平上在 Drosha 和 Dicer cKO 雄性之间相似，但 Drosha cKO 睾丸在生殖细胞破坏方面似乎比 Dicer cKO 睾丸更严重。微阵列分析显示 Drosha 和 Dicer 缺失的粗线期精母细胞或圆形精子细胞之间存在转录组差异。尽管性连锁 mRNA 的水平略有升高，但减数分裂性染色体失活似乎正常发生。我们的数据表明，与需要几种小 RNA 物种生物发生的 DICER 不同，DROSHA 主要对于经典 miRNA 的产生是必需的，并且 DROSHA 介导的 miRNA 产生对于正常的精子发生和雄性生育力是必需的。
