Hen1 is required for oocyte development and piRNA stability in zebrafish.
Piwi-interacting RNAs (piRNAs) are germ line-specific small RNA molecules that have a function in genome defence and germ cell development. They associate with a specific class of Argonaute proteins, named Piwi, and function through an RNA interference-like mechanism. piRNAs carry a 2'-O-methyl modification at their 3' end, which is added by the Hen1 enzyme. We show that zebrafish hen1 is specifically expressed in germ cells and is essential for maintaining a female germ line, whereas it is dispensable in the testis. Hen1 protein localizes to nuage through its C-terminal domain, but is not required for nuage formation. In hen1 mutant testes, piRNAs become uridylated and adenylated. Uridylation frequency is highest on retro-transposon-derived piRNAs and is accompanied by decreased piRNA levels and mild derepression of transposon transcripts. Altogether, our data suggest the existence of a uridylation-mediated 3'-5' exonuclease activity acting on piRNAs in zebrafish germ cells, which is counteracted by nuage-bound Hen1 protein. This system discriminates between piRNA targets and is required for ovary development and fully efficient transposon silencing.
Kamminga
Leonie M
LM
Hubrecht Institute-KNAW, University Medical Centre Utrecht, Utrecht, The Netherlands.
Luteijn
Maartje J
MJ
den Broeder
Marjo J
MJ
Redl
Stefan
S
Kaaij
Lucas J T
LJ
Roovers
Elke F
EF
Ladurner
Peter
P
Berezikov
Eugene
E
Ketting
René F
RF
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D005260:Female; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D008297:Male; D008780:Methyltransferases / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism; D026721:RNA 3' End Processing / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018626:Retroelements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions; D013737:Testis / Q000166:cytology / Q000378:metabolism; D014529:Uridine / Q000378:metabolism*; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018626:Retroelements; D029961:Zebrafish Proteins; C472855:piwil1 protein, zebrafish; D008780:Methyltransferases; C553971:henmt1 protein, zebrafish; D014529:Uridine