title: Translational regulation of the DOUBLETIME/CKIδ/ε kinase by LARK contributes to circadian period modulation.
abstract: The Drosophila homolog of Casein Kinase I δ/ε, DOUBLETIME (DBT), is required for Wnt, Hedgehog, Fat and Hippo signaling as well as circadian clock function. Extensive studies have established a critical role of DBT in circadian period determination. However, how DBT expression is regulated remains largely unexplored. In this study, we show that translation of dbt transcripts are directly regulated by a rhythmic RNA-binding protein (RBP) called LARK (known as RBM4 in mammals). LARK promotes translation of specific alternative dbt transcripts in clock cells, in particular the dbt-RC transcript. Translation of dbt-RC exhibits circadian changes under free-running conditions, indicative of clock regulation. Translation of a newly identified transcript, dbt-RE, is induced by light in a LARK-dependent manner and oscillates under light/dark conditions. Altered LARK abundance affects circadian period length, and this phenotype can be modified by different dbt alleles. Increased LARK delays nuclear degradation of the PERIOD (PER) clock protein at the beginning of subjective day, consistent with the known role of DBT in PER dynamics. Taken together, these data support the idea that LARK influences circadian period and perhaps responses of the clock to light via the regulated translation of DBT. Our study is the first to investigate translational control of the DBT kinase, revealing its regulation by LARK and a novel role of this RBP in Drosophila circadian period modulation.
authors.affiliation: Department of Neuroscience, Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Biology, York College, Jamaica, New York, New York, United States of America.
authors.forename: Gerard P
authors.initials: GP
authors.lastname: McNeil
authors.affiliation: Department of Neuroscience, Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: F Rob
authors.initials: FR
authors.lastname: Jackson
mesh_terms: D000483:Alleles; D000818:Animals; D048149:Casein Kinase 1 epsilon / Q000235:genetics*; D057906:Circadian Clocks / Q000235:genetics*; D002940:Circadian Rhythm / Q000235:genetics; D003624:Darkness; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D008027:Light; D056950:Period Circadian Proteins / Q000235:genetics; D014176:Protein Biosynthesis / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*
chemical_list: D029721:Drosophila Proteins; C105214:Lark protein, Drosophila; D056950:Period Circadian Proteins; D016601:RNA-Binding Proteins; C113519:dco protein, Drosophila; D048149:Casein Kinase 1 epsilon