title: Uniting germline and stem cells: the function of Piwi proteins and the piRNA pathway in diverse organisms.
abstract: The topipotency of the germline is the full manifestation of the pluri- and multipotency of embryonic and adult stem cells, thus the germline and stem cells must share common mechanisms that guarantee their multipotentials in development. One of the few such known shared mechanisms is represented by Piwi proteins, which constitute one of the two subfamilies of the Argonaute protein family. Piwi proteins bind to Piwi-interacting RNAs (piRNAs) that are generally 26 to 31 nucleotides in length. Both Piwi proteins and piRNAs are most abundantly expressed in the germline. Moreover, Piwi proteins are expressed broadly in certain types of somatic stem/progenitor cells and other somatic cells across animal phylogeny. Recent studies indicate that the Piwi-piRNA pathway mediates epigenetic programming and posttranscriptional regulation, which may be responsible for its function in germline specification, gametogenesis, stem cell maintenance, transposon silencing, and genome integrity in diverse organisms.
authors.affiliation: Yale Stem Cell Center and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06509, USA. haifan.lin@yale.edu
authors.forename: Celina
authors.initials: C
authors.lastname: Juliano
authors.forename: Jianquan
authors.initials: J
authors.lastname: Wang
authors.forename: Haifan
authors.initials: H
authors.lastname: Lin
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements; D004330:Drosophila / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D044127:Epigenesis, Genetic; D019143:Evolution, Molecular; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D014176:Protein Biosynthesis; D054730:Protein Interaction Domains and Motifs; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012098:Reproduction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
chemical_list: D060565:Argonaute Proteins; D004251:DNA Transposable Elements; C421088:PIWIL1 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012097:Repressor Proteins