Project description:The Jasmonate pathway regulators MYC2, MYC3 and MYC4 are central nodes in plant signaling networks integrating environmental and developmental signals to fine-tune jasmonate defenses and plant growth. Hence, their activity needs to be tightly regulated in order to optimize plant fitness. Among the increasing number of mechanisms regulating MYCs activity, protein stability is arising as a major player. However, how the levels of MYCs proteins are modulated is still poorly understood. Here, we report that MYC2, MYC3 and MYC4 are targets of BPM proteins, which act as substrate adaptors of CUL3-based E3 ubiquitin ligases. Reduction-of-function of CUL3BPM in amiR-bpm lines, bpm235 triple mutants and cul3ab double mutants enhances MYC2 and MYC3 stability and accumulation, and potentiates plant responses to JA such as root-growth inhibition, and MYC-regulated gene expression. BPM3 protein is stabilized by JA, suggesting a new negative feed-back regulatory mechanism to control MYCs activity. Our results uncover a new layer for JA-pathway regulation by CUL3BPM–mediated degradation of MYC TFs.
Project description:The Jasmonate pathway regulators MYC2, MYC3 and MYC4 are central nodes in plant signaling networks integrating environmental and developmental signals to fine-tune jasmonate defenses and plant growth. Hence, their activity needs to be tightly regulated in order to optimize plant fitness. Among the increasing number of mechanisms regulating MYCs activity, protein stability is arising as a major player. However, how the levels of MYCs proteins are modulated is still poorly understood. Here, we report that MYC2, MYC3 and MYC4 are targets of BPM proteins, which act as substrate adaptors of CUL3-based E3 ubiquitin ligases. Reduction-of-function of CUL3BPM in amiR-bpm lines, bpm235 triple mutants and cul3ab double mutants enhances MYC2 and MYC3 stability and accumulation, and potentiates plant responses to JA such as root-growth inhibition, and MYC-regulated gene expression. BPM3 protein is stabilized by JA, suggesting a new negative feed-back regulatory mechanism to control MYCs activity. Our results uncover a new layer for JA-pathway regulation by CUL3BPM–mediated degradation of MYC TFs.
Project description:Nitrate regulates plant growth and development and acts as a potent signal to control gene expression in Arabidopsis. Using an integrative bioinformatics approach we identified TGA1 and TGA4 as putative regulatory factors that mediate nitrate responses in Arabidopsis thaliana roots. We showed that both TGA1 and TGA4 mRNAs accumulate strongly and quickly after nitrate treatments in root organs in a tissue-specific manner. Phenotypic analysis of tga1/tga4 double mutant plants indicated that TGA1 and TGA4 are necessary for nitrate modulation of both primary and lateral root growth. Global gene expression analysis revealed that 97% of the genes with altered expression in tga1/tga4 double mutant plants are regulated by nitrate treatments indicating these transcription factors have a specific role in nitrate responses in Arabidopsis root organs. Among the nitrate-responsive genes that depend on TGA1/TGA4 for normal regulation of gene expression, we found nitrate transporters NRT2.1, NRT2.2 and nitrite reductase (NIR) genes. Specific binding of TGA1 to its cognate DNA sequence on the target gene promoters was confirmed by chromatin immunoprecipitation assays. These results identify TGA1 and TGA4 as important regulatory factors of the nitrate response in Arabidopsis roots.
Project description:Alternative polyadenylation (APA) refers to the regulated selection of polyadenylation sites (PASs) in transcripts, which affects the length of their 3’ untranslated regions (3’UTRs). APA regulates stage- and tissue-specific gene expression by affecting the stability, subcellular localization or translation rate of transcripts. We have recently shown that SRSF3 and SRSF7, two closely related SR proteins, link APA to mRNA export. However, the underlying mechanism for APA regulation by SRSF3 and SRSF7 remained unknown. Here, we combined iCLIP and 3’-end sequencing to find that both proteins bind upstream of proximal PAS (pPAS), but exert opposing effects on 3’UTR length. We show that SRSF7 enhances pPAS usage in a splicing-independent and concentration-dependent manner by recruiting the cleavage factor FIP1, thereby generating short 3’UTRs. SRSF7-specific domains that are absent in SRSF3 are necessary and sufficient for FIP1 recruitment. SRSF3 promotes long 3’UTRs by maintaining high levels of the cleavage factor Im (CFIm) via alternative splicing. Using iCLIP, we show that CFIm binds before and after the pPASs of SRSF3 targets, which masks them and inhibits polyadenylation. In the absence of SRSF3, CFIm levels are strongly reduced, which exposes the pPASs and leads to shorter 3’UTRs. Conversely, during cellular differentiation, 3’UTRs are massively extended, while the levels of SRSF7 and FIP1 strongly decline. Altogether, our data suggest that SRSF7 acts as a sequence-specific enhancer of pPASs, while SRSF3 inhibits pPAS usage by controlling CFIm levels. Our data shed light on a long-standing puzzle of how one factor (CFIm) can inhibit and enhance PAS usage.
Project description:Nitric oxide regulates plant development and responses to stress. However, the mechanisms underlying its regulatory role are still poorly known, and the impact of endogenous NO on the genome-wide transcriptome of plants has not been studied. For that purpose, we compared the transcriptomes of NO-deficient nia1nia2, noa1-2 and nia1nia2noa1-2 mutant versus wild type Arabidopsis thaliana plants. A core comprising 66 NO-responsive genes with similar expression in all NO-deficient genotypes was identified. Among them, 46 were down- and 20 up-regulated in NO-deficient plants, and thus positively and negatively regulated by endogenous NO, respectively. Accordingly with changes in its transcriptome, the NO-deficient nia1nia2noa1-2 mutant accumulated anthocyanins and indolic glucosinolates, displayed abnormal iron homeostasis in shoots and roots, and also showed altered root sensitivity to hormones such as ABA, ET, CYK and IAA. Together the presented data suggest NO functions essentially as a modulator of hormone action.
Project description:Iodine treatments specifically regulated the expression of several genes in shoot and root tissues, mostly involved in the plant defence response, suggesting the protective role of iodine against both biotic and abiotic stresses.
Project description:Role of alternative polyadenylation (APA) in rat brain after vaporized cannabis plant matter (CPM) exposure remains largely undetermined. Our WTTS-seq approach to capture 3'-end of RNAs clearly revealed alternative polyadenylation events responsible for dominantly down-regulates APA expression on Glutamatergic Transcripts in rats after CPM Exposure.
Project description:As sessile organisms, plants require dynamic pathways in order to recognize pathogens and coordinate plant defenses by signalling. Agrobacterium tumefaciens C58 is able to avoid triggering plant defenses prior to entering the cell, and therefore is only detected once infection has begun making Agrobacterium a plant pathogen to numerous plant species. Understanding plant responses to Agrobacterium will be useful in improving plant defenses and potentially may also improve plant transformation efficiency. Microarrays were utilized for detailing the global gene expression pattern in A. thaliana Col-0 roots in response to A. tumefaciens C58 for the identification of differentially expressed genes. 3-week-old A.thaliana Col-0 seedlings were selected for growth in hydroponic systems. A. tumefaciens C58 was inoculated into the hydroponic system and co-cultivation persisted for 8 hours. Root tissue was seperated for RNA extraction and hybridization to the ATH1 Affymetrix microarray.
Project description:Alternative cleavage and polyadenylation (APA) results in mRNA isoforms containing different 3’ untranslated regions (3’UTRs) and/or coding sequences. How core cleavage and polyadenylation (C/P) factors regulate APA is not well understood. Using siRNA knockdown coupled with deep sequencing, we found that several C/P factors can play significant roles in 3’UTR-APA. Whereas Pcf11 and Fip1 enhance usage of proximal poly(A) sites (pAs), CFI-25/68, PABPN1, and PABPC1 promote usage of distal pAs. Strong cis element biases were found for pAs regulated by CFI or Fip1, and the distance between pAs plays an important role in APA regulation. In addition, intronic pAs are substantially regulated by splicing factors, with U1 mostly influencing C/P events in 5’ introns and U2 impacting those in efficiently spliced introns. Furthermore, PABPN1 regulates expression of transcripts with pAs near the transcription start site, a property possibly related to its role in RNA degradation. Finally, we found that groups of APA events regulated by C/P factors are also modulated in cell differentiation and development with distinct trends. Together, our results indicate that the abundance of different C/P factors and splicing factors plays diverse roles in APA, and is relevant to APA regulation in biological conditions. knockdown experiments of 23 C/P factors, 3 splicing factors and U1D in mouse C2C12 myoblast cells