title: A role for Piwi and piRNAs in germ cell maintenance and transposon silencing in Zebrafish.
abstract: Piwi proteins specify an animal-specific subclass of the Argonaute family that, in vertebrates, is specifically expressed in germ cells. We demonstrate that zebrafish Piwi (Ziwi) is expressed in both the male and the female gonad and is a component of a germline-specifying structure called nuage. Loss of Ziwi function results in a progressive loss of germ cells due to apoptosis during larval development. In animals that have reduced Ziwi function, germ cells are maintained but display abnormal levels of apoptosis in adults. In mammals, Piwi proteins associate with approximately 29-nucleotide-long, testis-specific RNA molecules called piRNAs. Here we show that zebrafish piRNAs are present in both ovary and testis. Many of these are derived from transposons, implicating a role for piRNAs in the silencing of repetitive elements in vertebrates. Furthermore, we show that piRNAs are Dicer independent and that their 3' end likely carries a 2'O-Methyl modification.
authors.affiliation: Hubrecht Laboratory, Uppsalalaan 8, Utrecht, Netherlands.
authors.forename: Saskia
authors.initials: S
authors.lastname: Houwing
authors.forename: Leonie M
authors.initials: LM
authors.lastname: Kamminga
authors.forename: Eugene
authors.initials: E
authors.lastname: Berezikov
authors.forename: Daniela
authors.initials: D
authors.lastname: Cronembold
authors.forename: Angélique
authors.initials: A
authors.lastname: Girard
authors.forename: Hans
authors.initials: H
authors.lastname: van den Elst
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Filippov
authors.forename: Heiko
authors.initials: H
authors.lastname: Blaser
authors.forename: Erez
authors.initials: E
authors.lastname: Raz
authors.forename: Cecilia B
authors.initials: CB
authors.lastname: Moens
authors.forename: Ronald H A
authors.initials: RH
authors.lastname: Plasterk
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Hannon
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Draper
authors.forename: René F
authors.initials: RF
authors.lastname: Ketting
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D005260:Female; D016678:Genome; D005854:Germ Cells / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D008297:Male; D010053:Ovary / Q000166:cytology; D034622:RNA Interference; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D018626:Retroelements; D013737:Testis / Q000166:cytology; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D022661:RNA, Untranslated; D016601:RNA-Binding Proteins; D018626:Retroelements; D029961:Zebrafish Proteins; C472855:piwil1 protein, zebrafish