Abstract
BackgroundThe Ccr4-Not complex is a key eukaryotic regulator of gene transcription and cytoplasmic mRNA degradation. Whether this complex also affects aspects of post-transcriptional gene regulation, such as mRNA export, remains largely unexplored. Human Caf1 (hCaf1), a Ccr4-Not complex member, interacts with and regulates the arginine methyltransferase PRMT1, whose targets include RNA binding proteins involved in mRNA export. However, the functional significance of this regulation is poorly understood.Methodology/Principal FindingsHere we demonstrate using co-immunoprecipitation approaches that Ccr4-Not subunits interact with Hmt1, the budding yeast ortholog of PRMT1. Furthermore, using genetic and biochemical approaches, we demonstrate that Ccr4-Not physically and functionally interacts with the heterogenous nuclear ribonucleoproteins (hnRNPs) Nab2 and Hrp1, and that the physical association depends on Hmt1 methyltransferase activity. Using mass spectrometry, co-immunoprecipitation and genetic approaches, we also uncover physical and functional interactions between Ccr4-Not subunits and components of the nuclear pore complex (NPC) and we provide evidence that these interactions impact mRNA export.Conclusions/SignificanceTaken together, our findings suggest that Ccr4-Not has previously unrealized functional connections to the mRNA processing/export pathway that are likely important for its role in gene expression. These results shed further insight into the biological functions of Ccr4-Not and suggest that this complex is involved in all aspects of mRNA biogenesis, from the regulation of transcription to mRNA export and turnover.
Highlights
Gene expression is regulated at multiple levels, including at the stages of transcriptional and post-transcriptional control, to achieve correct levels and patterns of expression [1]
A previous study identified one of the human homologs of yeast Caf1, hCAF1, as a regulator of the arginine methyltransferase PRMT1 [42]. To determine whether this functional relationship is evolutionarily conserved in the yeast Saccharomyces cerevisiae, we performed co-immunoprecipitation experiments to determine whether Hmt1, the budding yeast ortholog of PRMT1 [43], physically associates with components of the Ccr4-Not complex
Our results identify new connections between the Ccr4-Not complex and the mRNA processing and export machinery through physical and functional interactions both with heterogenous nuclear ribonucleoproteins (hnRNPs) and the nuclear pore complex (NPC)
Summary
Gene expression is regulated at multiple levels, including at the stages of transcriptional and post-transcriptional control, to achieve correct levels and patterns of expression [1]. There is mounting evidence that the steps from transcription to mRNA export are sequential, but are highly coupled and interdependent, whereby proteins involved in one step of mRNA biogenesis are subsequently used as adaptor proteins to recruit other processing or export factors [1,2,3,4,5,6] Among these RNA binding proteins are the historically defined heterogenous nuclear ribonucleoproteins (hnRNPs) which mediate multiple steps in the mRNA lifecycle such as processing, nuclear export, and delivery to the cytoplasm [7,8]. The functional significance of this regulation is poorly understood
Sign-in/Register to view highlights & summary 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.
