title: Two cellular protein kinases, DNA-PK and PKA, phosphorylate the adenoviral L4-33K protein and have opposite effects on L1 alternative RNA splicing.
abstract: Accumulation of the complex set of alternatively processed mRNA from the adenovirus major late transcription unit (MLTU) is subjected to a temporal regulation involving both changes in poly (A) site choice and alternative 3' splice site usage. We have previously shown that the adenovirus L4-33K protein functions as an alternative splicing factor involved in activating the shift from L1-52,55K to L1-IIIa mRNA. Here we show that L4-33K specifically associates with the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) in uninfected and adenovirus-infected nuclear extracts. Further, we show that L4-33K is highly phosphorylated by DNA-PK in vitro in a double stranded DNA-independent manner. Importantly, DNA-PK deficient cells show an enhanced production of the L1-IIIa mRNA suggesting an inhibitory role of DNA-PK on the temporal switch in L1 alternative RNA splicing. Moreover, we show that L4-33K also is phosphorylated by protein kinase A (PKA), and that PKA has an enhancer effect on L4-33K-stimulated L1-IIIa splicing. Hence, we demonstrate that these kinases have opposite effects on L4-33K function; DNA-PK as an inhibitor and PKA as an activator of L1-IIIa mRNA splicing. Taken together, this is the first report identifying protein kinases that phosphorylate L4-33K and to suggest novel regulatory roles for DNA-PK and PKA in adenovirus alternative RNA splicing.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
authors.forename: Heidi
authors.initials: H
authors.lastname: Törmänen Persson
authors.forename: Anne Kristin
authors.initials: AK
authors.lastname: Aksaas
authors.forename: Anne Katrine
authors.initials: AK
authors.lastname: Kvissel
authors.forename: Tanel
authors.initials: T
authors.lastname: Punga
authors.forename: Åke
authors.initials: Å
authors.lastname: Engström
authors.forename: Bjørn Steen
authors.initials: BS
authors.lastname: Skålhegg
authors.forename: Göran
authors.initials: G
authors.lastname: Akusjärvi
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000257:Adenoviridae Infections / Q000201:enzymology / Q000821:virology; D017398:Alternative Splicing / Q000235:genetics*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D010766:Phosphorylation; D011061:Poly A / Q000235:genetics*; D011485:Protein Binding; D040901:Proteomics; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D014764:Viral Proteins; D011061:Poly A; D051747:DNA-Activated Protein Kinase; D017868:Cyclic AMP-Dependent Protein Kinases