Project description:Genome-wide identification of PIF3-binding sites and direct-target genes of PIF3 transcriptional regulation in skotomorphogenesis [RNA-Seq]
Project description:Genome-wide identification of PIF3-binding sites and direct-target genes of PIF3 transcriptional regulation in skotomorphogenesis [ChIP-Seq]
Project description:Light-environment signals, sensed by plant phytochrome (phy) photoreceptors, are transduced to target genes through direct regulation of PHYTOCHROME-INTERACTING FACTOR (PIF) transcription factor abundance and activity. Previous genome-wide DNA-binding and expression analysis has identified a set of genes that are direct targets of PIF transcriptional regulation. However, quantitative analysis of promoter occupancy versus expression level has suggested that unknown “trans factors” modulate the intrinsic transcriptional activation activity of DNA-bound PIF proteins. Here, using computational analysis of published data, we have identified PSEUDO-RESPONSE REGULATORS (PRR5 and PRR7) as displaying a high frequency of co-localization with the PIF proteins at their binding sites in the promoters of PIF Direct Target Genes (DTGs). We show that the PRRs function to suppress PIF-stimulated growth in the light and vegetative shade, and that they repress the rapid PIF-induced expression of PIF-DTGs triggered by exposure to shade. The repressive action of the PRRs on both growth and DTG expression requires the PIFs, indicating direct action on PIF activity, rather than a parallel antagonistic pathway. Protein interaction assays indicate that the PRRs exert their repressive activity by binding directly to the PIF proteins in the nucleus. These findings support the conclusion that the PRRs function as direct outputs from the core circadian oscillator, to regulate the expression of PIF-DTGs, through modulation of PIF transcriptional activation activity, thus expanding the roles of the multifunctional PIF signaling hub.
Project description:Dark-grown seedlings exhibit skotomorphogenic development. Genetic and molecular evidence indicates that a quartet of Arabidopsis Phytochrome (phy)-Interacting bHLH Factors (PIF1, 3, 4 and 5) are critically necessary to maintaining this developmental state, and that light activation of phy induces a switch to photomorphogenic development by inducing rapid degradation of the PIFs. Here, using combined ChIP-seq and RNA-seq analyses, we have identified genes that are direct targets of PIF1 transcriptional regulation, and we provide evidence that the quartet collectively regulate these genes by shared, direct binding to the target promoters in promoting skotomorphogenesis. Three biological replicates data of PIF1-binding sites were collected by comparing the parallel ChIP samples from Myc-epitope-tagged-PIF1 (P1M) overexpressing transgenic seedlings and the wild-type (WT) control.
Project description:Dark-grown seedlings exhibit skotomorphogenic development. Genetic and molecular evidence indicates that a quartet of Arabidopsis Phytochrome (phy)-Interacting bHLH Factors (PIF4, 3, 4 and 5) are critically necessary to maintaining this developmental state, and that light activation of phy induces a switch to photomorphogenic development by inducing rapid degradation of the PIFs. Here, using combined ChIP-seq and RNA-seq analyses, we have identified genes that are direct targets of PIF4 transcriptional regulation, and we provide evidence that the quartet collectively regulate these genes by shared, direct binding to the target promoters in promoting skotomorphogenesis. Three biological replicates data of PIF4-binding sites were collected by comparing the parallel ChIP samples from Myc-epitope-tagged-PIF4 (P1M) overexpressing transgenic seedlings and the wild-type (WT) control.
Project description:Dark-grown seedlings exhibit skotomorphogenic development. Genetic and molecular evidence indicates that a quartet of Arabidopsis Phytochrome (phy)-Interacting bHLH Factors (PIF1, 3, 4 and 5) are critically necessary to maintaining this developmental state, and that light activation of phy induces a switch to photomorphogenic development by inducing rapid degradation of the PIFs. Here, using combined ChIP-seq and RNA-seq analyses, we have identified genes that are direct targets of PIF3 transcriptional regulation, and we provide evidence that the quartet collectively regulate these genes by shared, direct binding to the target promoters in promoting skotomorphogenesis. Four biological replicates data of PIF3-binding sites were collected by comparing the parallel ChIP samples from transgenic seedlings overexpressing Myc-epitope-tagged PIF3 (35S:PIF3-5xMyc, P3M) in pif3-3 null mutant background and the wild-type (WT) control.
Project description:Auxin is a major plant hormone for both development and environmental adaptation. Auxin responses are context dependent and highly modulated by light, temperature, the circadian clock, brassinosteroid, and gibberellin, but the underlying mechanisms remain unclear. Here, we show that auxin signaling integrates with other signals through direct interactions of AUXIN RESPONSE FACTOR6 (ARF6) with PHYTOCHROME INTERACTING FACTOR4 (PIF4), the brassinosteroid-signaling transcription factor BZR1, and the gibberellin-signaling repressor RGA. ChIP-Seq and RNA-Seq experiments show that ARF6, PIF4, and BZR1 bind to largely overlapping targets in the genome and synergistically activate gene expression. In vitro and in vivo assays show that ARF6-promoter binding is enhanced by PIF4 and BZR1 but blocked by RGA. Furthermore, a tripartite HLH/bHLH module feedback regulates PIF activity and thus modulates auxin sensitivity according to additional developmental and environmental cues. Our results demonstrate a central growth-regulation transcriptional network that coordinates hormonal, environmental, and developmental control of cell elongation and plant growth. Genome-wide identification of ARF6 DNA-binding sites in etiolated Arabidopsis seedlings.