title: MicroRNA biogenesis is required for mouse primordial germ cell development and spermatogenesis.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are critical regulators of transcriptional and post-transcriptional gene silencing, which are involved in multiple developmental processes in many organisms. Apart from miRNAs, mouse germ cells express another type of small RNA, piwi-interacting RNAs (piRNAs). Although it has been clear that piRNAs play a role in repression of retrotransposons during spermatogenesis, the function of miRNA in mouse germ cells has been unclear.
  
  
  RESULTS
  In this study, we first revealed the expression pattern of miRNAs by using a real-time PCR-based 220-plex miRNA expression profiling method. During development of germ cells, miR-17-92 cluster, which is thought to promote cell cycling, and the ES cell-specific cluster encoding miR-290 to -295 (miR-290-295 cluster) were highly expressed in primordial germ cells (PGCs) and spermatogonia. A set of miRNAs was developmentally regulated. We next analysed function of miRNA biogenesis in germ cell development by using conditional Dicer-knockout mice in which Dicer gene was deleted specifically in the germ cells. Dicer-deleted PGCs and spermatogonia exhibited poor proliferation. Retrotransposon activity was unexpectedly suppressed in Dicer-deleted PGCs, but not affected in the spermatogonia. In Dicer-deleted testis, spermatogenesis was retarded at an early stage when proliferation and/or early differentiation. Additionally, we analysed spermatogenesis in conditional Argonaute2-deficient mice. In contrast to Dicer-deficient testis, spermatogenesis in Argonaute2-deficient testis was indistinguishable from that in wild type.
  
  
  CONCLUSIONS
  These results illustrate that miRNAs are important for the proliferation of PGCs and spermatogonia, but dispensable for the repression of retrotransposons in developing germ cells. Consistently, miRNAs promoting cell cycling are highly expressed in PGCs and spermatogonia. Furthermore, based on normal spermatogenesis in Argonaute2-deficient testis, the critical function of Dicer in spermatogenesis is independent of Argonaute2.
authors.affiliation: Wellcome Trust/Cancer Research United Kingdom Gurdon Institute, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Hayashi
authors.forename: Susana M
authors.initials: SM
authors.lastname: Chuva de Sousa Lopes
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kaneda
authors.forename: Fuchou
authors.initials: F
authors.lastname: Tang
authors.forename: Petra
authors.initials: P
authors.lastname: Hajkova
authors.forename: Kaiqin
authors.initials: K
authors.lastname: Lao
authors.forename: Donal
authors.initials: D
authors.lastname: O'Carroll
authors.forename: Partha P
authors.initials: PP
authors.lastname: Das
authors.forename: Alexander
authors.initials: A
authors.lastname: Tarakhovsky
authors.forename: Eric A
authors.initials: EA
authors.lastname: Miska
authors.forename: M Azim
authors.initials: MA
authors.lastname: Surani
mesh_terms: D000818:Animals; D060565:Argonaute Proteins; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D053487:DEAD-box RNA Helicases / Q000502:physiology; D019175:DNA Methylation; D004722:Endoribonucleases / Q000502:physiology; D015852:Eukaryotic Initiation Factor-2 / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation; D005854:Germ Cells / Q000254:growth & development* / Q000378:metabolism; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D019426:Integrases; D020084:Long Interspersed Nucleotide Elements / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics*; D034741:RNA, Small Interfering / Q000502:physiology; D043244:Ribonuclease III; D013091:Spermatogenesis / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000502:physiology; D044767:Ubiquitin-Protein Ligases
chemical_list: C526735:Ago2 protein, mouse; D060565:Argonaute Proteins; D015852:Eukaryotic Initiation Factor-2; D051034:Inhibitor of Apoptosis Proteins; D035683:MicroRNAs; D034741:RNA, Small Interfering; C494834:Birc2 protein, mouse; D044767:Ubiquitin-Protein Ligases; C045073:Cre recombinase; D019426:Integrases; D004722:Endoribonucleases; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases