title: Global decay of mRNA is a hallmark of apoptosis in aging Xenopus eggs.
abstract: Cytoplasmic mRNAs are specifically degraded in somatic cells as a part of early apoptotic response. However, no reports have been presented so far concerning mRNA fate in apoptotic gametes. In the present study, we analyzed the content of various cytoplasmic mRNAs in aging oocytes and eggs of the African clawed frog, Xenopus laevis. To circumvent large gene expression variation among the individual oocytes and eggs, single-cell monitoring of transcript levels has been implemented, using multiple cytoplasmic collections and reverse transcriptase quantitative PCR. It was found that numerous cytoplasmic mRNAs, coding for proteins classified in different functional types, are robustly degraded in apoptotic Xenopus eggs, but not in aging oocytes. mRNA degradation becomes evident in the eggs after meiotic exit at the time of cytochrome c release. A strong correlation between the length of PCR amplicon and specific transcript content was observed, suggesting endonucleolytic cleavage of mRNA. In addition, it was found that mRNA deadenylation also contributes to apoptotic mRNA degradation. Altogether, these findings indicate that the global decay of mRNA represents a hallmark of apoptosis in aging Xenopus eggs. To our knowledge, this is the first description of mRNA degradation in apoptotic gamete cells.
authors.affiliation: a Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama , Kita ku , Kyoto , Japan.|b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Tokmakov
authors.affiliation: b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Iguchi
authors.affiliation: b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan.
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Iwasaki
authors.affiliation: b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Fukami
authors.affiliation: a Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama , Kita ku , Kyoto , Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Sato
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D015415:Biomarkers; D016922:Cellular Senescence / Q000235:genetics*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D009865:Oocytes / Q000378:metabolism*; D011061:Poly A; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics*; D014981:Xenopus / Q000235:genetics*
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D011061:Poly A
keywords: Apoptosis; Xenopus eggs; deadenylation; endonucleolytic decay; mRNA; single-cell analysis