Mediator CDK subunits are platforms for interactions with various chromatin regulatory complexes.
The Mediator complex consists of more than 20 subunits. This is composed of four modules: head, middle, tail and CDK/Cyclin. Importantly, Mediator complex is known to play pivotal roles in transcriptional regulation, but its molecular mechanisms are still elusive. Many studies, including our own, have revealed that CDK8, a kinase subunit of the CDK/Cyclin module, is one of the key subunits involved in these roles. Additionally, we previously demonstrated that a novel CDK component, CDK19, played similar roles. It is assumed that various factors that directly affect transcriptional regulation target these two CDKs; thus, we conducted yeast two-hybrid screenings to isolate the CDK19-interacting proteins. From a screening of 40 million colonies, we obtained 287 clones that provided positive results encoded mRNAs, and it turned out that 59 clones of them encoded nuclear proteins. We checked the reading frames of the candidate clones and obtained three positive clones, all of which encoded the transcriptional cofactors, Brahma-related gene 1, B-cell CLL/lymphoma 6 and suppressor of zeste 12 homolog. Intriguingly, these three cofactors are also related to chromatin regulation. Further studies demonstrated that those could bind not only to CDK19 but also to CDK8. These results help elucidate the functional mechanism for the mutual regulations between transcription and chromatin.
Laboratory of Gene Regulation, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
Rikiya
R
Fukasawa
Taiki
T
Tsutsui
Yutaka
Y
Hirose
Aki
A
Tanaka
Yoshiaki
Y
Ohkuma
D002843:Chromatin / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D056892:Mediator Complex / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism*; D009363:Neoplasm Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D063151:Polycomb Repressive Complex 2 / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000378:metabolism*; D051560:Proto-Oncogene Proteins c-bcl-6; D017384:Sequence Deletion / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
C084103:BCL6 protein, human; D002843:Chromatin; D004268:DNA-Binding Proteins; D056892:Mediator Complex; D046912:Multiprotein Complexes; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D021122:Protein Subunits; D051560:Proto-Oncogene Proteins c-bcl-6; C430461:SUZ12 protein, human; D014157:Transcription Factors; D063151:Polycomb Repressive Complex 2; D018844:Cyclin-Dependent Kinases; C084108:SMARCA4 protein, human; D004265:DNA Helicases