Abstract
The Nrf2 transcription factor is well conserved throughout metazoan evolution and serves as a central regulator of adaptive cellular responses to oxidative stress. We carried out an RNAi screen in Drosophila S2 cells to better understand the regulatory mechanisms governing Nrf2 target gene expression. This paper describes the identification and characterization of the RNA polymerase II (Pol II) kinase Cdk12 as a factor that is required for Nrf2 target gene expression in cell culture and in vivo. Cdk12 is, however, not essential for bulk mRNA transcription and cells lacking CDK12 function are viable and able to proliferate. Consistent with previous findings on the DNA damage and heat shock responses, it emerges that Cdk12 may be specifically required for stress activated gene expression. Transcriptome analysis revealed that antioxidant gene expression is compromised in flies with reduced Cdk12 function, which makes them oxidative stress sensitive. In addition to supporting Reactive Oxygen Species (ROS) induced gene activation, Cdk12 suppresses genes that support metabolic functions in stressed conditions. We suggest that Cdk12 acts as a gene-selective Pol II kinase that engages a global shift in gene expression to switch cells from a metabolically active state to “stress-defence mode” when challenged by external stress.
Highlights
Nrf[2] homolog in Drosophila is the CncC protein, one of several gene products that are generated from the cnc locus by alternative splicing[5,11,12]
Nrf2-responsive ARE-firefly-luciferase (ARE-Fluc) and Act5C-renilla-luciferase (Act5C-Rluc) plasmid constructs served as reporters for CncC transcriptional activity and internal control, respectively (Fig. 1B)
We present the polymerase II (Pol II) C-terminal domain (CTD) kinase CDK12 as a novel factor that is required for the function of CncC, the Drosophila homolog of the Nrf[2] transcription factor
Summary
Nrf[2] homolog in Drosophila is the CncC protein, one of several gene products that are generated from the cnc (cap’n’collar) locus by alternative splicing[5,11,12]. In an effort to better understand the regulatory mechanisms controlling Nrf[2], we carried out an unbiased RNAi screen to identify novel regulators of CncC pathway activity. The screen found Cdk[12], a Pol II kinase[13], to be required for efficient CncC target gene activation. Our results corroborate and extend recent findings which suggest that Cdk[12] acts as a gene-selective Pol II kinase with specialized functions in different types of cellular stress responses[13,14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
