title: Involvement of cyclin K posttranscriptional regulation in the formation of Artemia diapause cysts.
abstract: BACKGROUND
  Artemia eggs tend to develop ovoviviparously to yield nauplius larvae in good rearing conditions; while under adverse situations, they tend to develop oviparously and encysted diapause embryos are formed instead. However, the intrinsic mechanisms regulating this process are not well understood.
  
  
  RESULTS
  This study has characterized the function of cyclin K, a regulatory subunit of the positive transcription elongation factor b (P-TEFb) in the two different developmental pathways of Artemia. In the diapause-destined embryo, Western blots showed that the cyclin K protein was down-regulated as the embryo entered dormancy and reverted to relatively high levels of expression once development resumed, consistent with the fluctuations in phosphorylation of position 2 serines (Ser2) in the C-terminal domain (CTD) of the largest subunit (Rpb1) of RNA polymerase II (RNAP II). Interestingly, the cyclin K transcript levels remained constant during this process. In vitro translation data indicated that the template activity of cyclin K mRNA stored in the postdiapause cyst was repressed. In addition, in vivo knockdown of cyclin K in developing embryos by RNA interference eliminated phosphorylation of the CTD Ser2 of RNAP II and induced apoptosis by inhibiting the extracellular signal-regulated kinase (ERK) survival signaling pathway.
  
  
  CONCLUSIONS
  Taken together, these findings reveal a role for cyclin K in regulating RNAP II activity during diapause embryo development, which involves the post-transcriptional regulation of cyclin K. In addition, a further role was identified for cyclin K in regulating the control of cell survival during embryogenesis through ERK signaling pathways.
authors.affiliation: Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Xia
authors.initials: X
authors.lastname: Ding
authors.forename: Xiang
authors.initials: X
authors.lastname: Ye
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Dai
authors.forename: Jin-Shu
authors.initials: JS
authors.lastname: Yang
authors.forename: Wei-Jun
authors.initials: WJ
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D001156:Artemia / Q000196:embryology* / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000201:enzymology / Q000502:physiology*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D021381:Protein Transport; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D016213:Cyclins; D012333:RNA, Messenger; D048049:Extracellular Signal-Regulated MAP Kinases; D012319:RNA Polymerase II