Project description:Eukaryotic messenger RNAs (mRNAs) possess a 5’-end N7-methyl guanosine (m7G) cap that promotes their translation and stability. However, it was recently demonstrated that eukaryotic mRNAs can also carry a 5' end nicotinamide adenine dinucleotide (NAD+) cap that promotes mRNA decay mediated by the NAD+ decapping enzyme DXO1. However, the dynamic regulation of NAD+ capping in plant remains unknown. Here, we describe the global landscape of NAD+-capped RNAs in Arabidopsis thaliana, and demonstrate that DXO1 is responsible for removal of these 5’-end modifications and facilitates mRNA degradation in plant transcriptomes. We also reveal that in the absence of DXO1 NAD+-capped mRNAs are unstable and processed into smRNAs. Furthermore, we find that Abscisic Acid (ABA) remodel the landscape of RNA cap epitransciptome, and the mRNA lost their NAD+ cap contribute to their stability under ABA. Overall, our results support a link between ABA response and RNA NAD+ capping.
Project description:Eukaryotic messenger RNAs (mRNAs) possess a 5’-end N7-methyl guanosine (m7G) cap that promotes their translation and stability. However, it was recently demonstrated that eukaryotic mRNAs can also carry a 5' end nicotinamide adenine dinucleotide (NAD+) cap that promotes mRNA decay mediated by the NAD+ decapping enzyme DXO1. However, the dynamic regulation of NAD+ capping in plant remains unknown. Here, we describe the global landscape of NAD+-capped RNAs in Arabidopsis thaliana, and demonstrate that DXO1 is responsible for removal of these 5’-end modifications and facilitates mRNA degradation in plant transcriptomes. We also reveal that in the absence of DXO1 NAD+-capped mRNAs are unstable and processed into smRNAs. Furthermore, we find that Abscisic Acid (ABA) remodel the landscape of RNA cap epitransciptome, and the mRNA lost their NAD+ cap contribute to their stability under ABA. Overall, our results support a link between ABA response and RNA NAD+ capping.
Project description:Bud dormancy is a crucial stage in perennial trees and allows survival over winter and optimal subsequent flowering and fruit production. Environmental conditions, and in particular temperature, have been shown to influence bud dormancy. Recent work highlighted some physiological and molecular events happening during bud dormancy in trees. However, we still lack a global understanding of transcriptional changes happening during bud dormancy. We conducted a fine tune temporal transcriptomic analysis of sweet cherry (Prunus avium L.) flower buds from bud organogenesis until the end of bud dormancy using next-generation sequencing. We observe that buds in organogenesis, paradormancy, endodormancy and ecodormancy are characterised by distinct transcriptional states, and associated with different pathways. We further identified that endodormancy can be separated in two phases based on its transcriptomic state: early and late endodormancy. We also found that transcriptional profiles of just 7 genes are enough to predict the main cherry tree flower buds dormancy stages. Our results indicate that transcriptional changes happening during dormancy are robust and conserved between different sweet cherry cultivars. Our work also sets the stage for the development of a fast and cost effective diagnostic tool to molecularly define the flower bud stage in cherry trees.
Project description:NAD besides its key role in cellular metabolism can serve as an alternative 5’ cap at several short non-coding RNAs. However, the function of the NAD cap remains elusive. Here, we investigate NAD capping of RNAs upon HIV-1 infection, which is associated with intracellular pellagra – depletion of NAD/NADH cellular pool. We applied NAD captureSeq on HIV-1 infected/noninfected cells and we revealed that four snRNAs (U1, U4ATAC, U5E and U7) and four snoRNAs (snord3G, snord102, snorA50A and snord3B) lost NAD cap upon HIV-1 infection. Interestingly, U1 snRNA was previously shown to be essential for HIV-1 replication. We provide evidence that the NAD cap reduces the stability of the U1 - HIV-1 pre-mRNA duplex. The importance of NAD RNA cap in HIV-1 infection was further supported by NAD decapping enzyme DXO overexpression, which led to increase in HIV-1 infectivity. This is the first example of NAD cap function in mammalian cells and suggests a general role of non-canonical RNA caps in antiviral innate immunity response.