title: Detection of PIWI and piRNAs in the mitochondria of mammalian cancer cells.
abstract: Piwi-interacting RNAs (piRNAs) are 26-31 nt small noncoding RNAs that are processed from their longer precursor transcripts by Piwi proteins. Localization of Piwi and piRNA has been reported mostly in nucleus and cytoplasm of higher eukaryotes germ-line cells, where it is believed that known piRNA sequences are located in repeat regions of nuclear genome in germ-line cells. However, localization of PIWI and piRNA in mammalian somatic cell mitochondria yet remains largely unknown. We identified 29 piRNA sequence alignments from various regions of the human mitochondrial genome. Twelve out 29 piRNA sequences matched stem-loop fragment sequences of seven distinct tRNAs. We observed their actual expression in mitochondria subcellular fractions by inspecting mitochondrial-specific small RNA-Seq datasets. Of interest, the majority of the 29 piRNAs overlapped with multiple longer transcripts (expressed sequence tags) that are unique to the human mitochondrial genome. The presence of mature piRNAs in mitochondria was detected by qRT-PCR of mitochondrial subcellular RNAs. Further validation showed detection of Piwi by colocalization using anti-Piwil1 and mitochondria organelle-specific protein antibodies.
authors.affiliation: Cancer Genomics Branch, National Cancer Center, Goyang 410-769, Republic of Korea. Electronic address: netbuyer@hanmail.net.
authors.forename: ChangHyuk
authors.initials: C
authors.lastname: Kwon
authors.affiliation: Department of Biochemistry, College of Medicine, Catholic University of Korea, Seoul 137-701, Republic of Korea. Electronic address: chuberry@naver.com.
authors.forename: Hyosun
authors.initials: H
authors.lastname: Tak
authors.affiliation: Department of Computer Science, Hanyang University, Seoul 133-791, Republic of Korea. Electronic address: minarho@hanyang.ac.kr.
authors.forename: Mina
authors.initials: M
authors.lastname: Rho
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center, Goyang 410-769, Republic of Korea. Electronic address: heyhae@ncc.re.kr.
authors.forename: Hae Ryung
authors.initials: HR
authors.lastname: Chang
authors.affiliation: New Experimental Therapeutics Branch, National Cancer Center, Goyang 410-769, Republic of Korea. Electronic address: yhkim@ncc.re.kr.
authors.forename: Yon Hui
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Molecular Epidemiology Branch, National Cancer Center, Goyang 410-769, Republic of Korea. Electronic address: bioktkim@ncc.re.kr.
authors.forename: Kyung Tae
authors.initials: KT
authors.lastname: Kim
authors.affiliation: Medical Sciences Program, Department of Cellular & Integrative Physiology, Indiana University School of Medicine, Bloomington, IN 47405, USA. Electronic address: curt.balch@gmail.com.
authors.forename: Curt
authors.initials: C
authors.lastname: Balch
authors.affiliation: Department of Biochemistry, College of Medicine, Catholic University of Korea, Seoul 137-701, Republic of Korea. Electronic address: leeek@catholic.ac.kr.
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Lee
authors.affiliation: Cancer Genomics Branch, National Cancer Center, Goyang 410-769, Republic of Korea. Electronic address: seungyoon.nam@ncc.re.kr.
authors.forename: Seungyoon
authors.initials: S
authors.lastname: Nam
mesh_terms: D060565:Argonaute Proteins / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D004272:DNA, Mitochondrial / Q000235:genetics; D020224:Expressed Sequence Tags; D054629:Genome, Mitochondrial; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D009369:Neoplasms / Q000235:genetics* / Q000378:metabolism*; D012313:RNA / Q000235:genetics* / Q000378:metabolism*; D000077278:RNA, Mitochondrial; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism*
chemical_list: D060565:Argonaute Proteins; D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D009363:Neoplasm Proteins; C421088:PIWIL1 protein, human; D000077278:RNA, Mitochondrial; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D012313:RNA
keywords: Bioinformatics; Genomics; Mitochondria; Non-coding RNAs; Piwi; Sequence analysis; Small RNA-Seq; piRNA