Mammalian microRNAs: experimental evaluation of novel and previously annotated genes. Chiang HR et al. MicroRNAs (miRNAs) are small regulatory RNAs that derive from distinctive hairpin transcripts. To learn more about the miRNAs of mammals, we sequenced 60 million small RNAs from mouse brain, ovary, testes, embryonic stem cells, three embryonic stages, and whole newborns. Analysis of these sequences confirmed 398 annotated miRNA genes and identified 108 novel miRNA genes. More than 150 previously annotated miRNAs and hundreds of candidates failed to yield sequenced RNAs with miRNA-like features. Ectopically expressing these previously proposed miRNA hairpins also did not yield small RNAs, whereas ectopically expressing the confirmed and newly identified hairpins usually did yield small RNAs with the classical miRNA features, including dependence on the Drosha endonuclease for processing. These experiments, which suggest that previous estimates of conserved mammalian miRNAs were inflated, provide a substantially revised list of confidently identified murine miRNAs from which to infer the general features of mammalian miRNAs. Our analyses also revealed new aspects of miRNA biogenesis and modification, including tissue-specific strand preferences, sequential Dicer cleavage of a metazoan precursor miRNA (pre-miRNA), consequential 5' heterogeneity, newly identified instances of miRNA editing, and evidence for widespread pre-miRNA uridylation reminiscent of miRNA regulation by Lin28. Thee are total of 200 conserved micrRNA only.
In this review, Figure 4 and Table 1 list ovarian microRNA.
General function
RNA processing
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Follicle development
Comment
Expression regulated by
FSH
Comment
A network of miRNAs expressed in the ovary are regulated by FSH. Yao N et al. The process of folliculogenesis requires a tightly regulated series of gene expression that are a pre-requisite to the development of ovarian follicle. Among these genes, follicle-stimulating hormone (FSH) is notable for its dual role in development of follicles as well as proliferation and differentiation of granulosa cells. The post-transcriptional expression of these genes is under the control of microRNAs (miRNAs), a class of small, endogenous RNAs that negatively impact gene expression. This study was carried out to determine the role of several miRNAs including mir-143, let-7a, mir-125b, let-7b, let-7c, mir-21 in follicular development in the mouse. The expression of these RNAs was very low in primordial follicles but these became readily detectable in the granulosa cells of primary, secondary and antral follicles. We show that this expression of some miRNAs (mir-143, let-7a, mir-15b) is under negative control of FSH. Together, these findings suggest that FSH regulates folliculogenesis by a novel pathway of miRNAs.