Project description:FOXE3 is a lens specific transcription factor that has been associated with anterior segment ocular dysgenesis. To determine the transcriptional target(s) of FOXE3 that are indispensable for the anterior segment development, we examined the transcriptome and the proteome of cells expressing truncated FOXE3 responsible for Peters anomaly identified through linkage-coupled next-generation whole exome sequencing. We found that DNAJB1, an autophagy-associated protein, was the only candidate exhibiting differential expression in both screens. We confirmed the candidacy of DNAJB1 through chromatin immunoprecipitation and luciferase assays while knockdown of DNAJB1 in human lens epithelial cells resulted in mitotic arrest. Subsequently, we targeted dnajb1a in zebrafish through injection of a splice-blocking morpholino. The dnajb1a morphants exhibited underdeveloped cataractous lenses with persistent apoptotic nuclei. In conclusion, here we report DNAJB1 as a transcriptional target of FOXE3 in a novel pathway that is crucial for the development of the anterior segment of the eye.
Project description:FOXE3 is a lens specific transcription factor that has been associated with anterior segment ocular dysgenesis. To determine the transcriptional target(s) of FOXE3 that are indispensable for the anterior segment development, we examined the transcriptome and the proteome of cells expressing truncated FOXE3 responsible for Peters anomaly identified through linkage-coupled next-generation whole exome sequencing. We found that DNAJB1, an autophagy-associated protein, was the only candidate exhibiting differential expression in both screens. We confirmed the candidacy of DNAJB1 through chromatin immunoprecipitation and luciferase assays while knockdown of DNAJB1 in human lens epithelial cells resulted in mitotic arrest. Subsequently, we targeted dnajb1a in zebrafish through injection of a splice-blocking morpholino. The dnajb1a morphants exhibited underdeveloped cataractous lenses with persistent apoptotic nuclei. In conclusion, we have identified DNAJB1 as a transcriptional target of FOXE3 in a novel pathway that is crucial for development of the anterior segment of the eye.
Project description:FOXE3 is a lens specific transcription factor that has been associated with anterior segment ocular dysgenesis. To determine the transcriptional target(s) of FOXE3 that are indispensable for the anterior segment development, we examined the transcriptome and the proteome of cells expressing truncated FOXE3 responsible for Peters anomaly identified through linkage-coupled next-generation whole exome sequencing. We found that DNAJB1, an autophagy-associated protein, was the only candidate exhibiting differential expression in both screens. We confirmed the candidacy of DNAJB1 through chromatin immunoprecipitation and luciferase assays while knockdown of DNAJB1 in human lens epithelial cells resulted in mitotic arrest. Subsequently, we targeted dnajb1a in zebrafish through injection of a splice-blocking morpholino. The dnajb1a morphants exhibited underdeveloped cataractous lenses with persistent apoptotic nuclei. In conclusion, we have identified DNAJB1 as a transcriptional target of FOXE3 in a novel pathway that is crucial for development of the anterior segment of the eye. Human Embryonic Kidney (HEK293FT) cells were transfected with the expression vector (pT-RexTM-DEST30) harboring either the wild type or the mutant (C240*) FOXE3 ORF (open reading frame). The experimental design included a total of eight biological replicates of cells expressing the wild type and eight replicates of mutant FOXE3 along with eight non-transfected controls. Cells were harvested 24-hour post-transfection and subjected to total RNA isolation for the preparation of whole transcriptome next-generation sequencing libraries. Initially, we examined the quality of transcriptome libraries on a MiSeq genome analyzer. Subsequent to confirmation of the quality, all libraries were paired-end sequenced (2 x 100 bp) using Illumina TruSeq Cluster V3 flow cell at a concentration of 13.0 pM in two separate lanes (12 bar-coded mRNA pooled libraries in each lane) on a HiSeq 2000 genome analyzer.
Project description:Developmental and homeostatic remodeling of cellular organelles is mediated by a complex process termed autophagy. The cohort of proteins that constitute the autophagy machinery function in a multistep biochemical pathway. Though components of the autophagy machinery are broadly expressed, autophagy can occur in specialized cellular contexts, and mechanisms underlying cell type-specific autophagy are poorly understood. We demonstrate that the master regulator of hematopoiesis GATA-1 directly activates transcription of genes encoding the essential autophagy component Microtubule Associated Protein 1 Light Chain 3B (LC3B) and its homologs (MAP1LC3A, GABARAP, GABARAPL1, GATE-16). In addition, GATA-1 directly activates genes involved in the biogenesis/function of lysosomes, which mediate autophagic protein turnover. We demonstrate that GATA-1 utilizes the forkhead protein FoxO3 to activate select autophagy genes. GATA-1-dependent LC3B induction is tightly coupled to accumulation of the active form of LC3B and autophagosomes, which mediate mitochondrial clearance as a critical step in erythropoiesis. These results illustrate a novel mechanism by which a master regulator of development establishes a genetic network to instigate cell type-specific autophagy. Genome-wide maps of GATA1 factor occupancy in primary human PBMC derived erythroblasts
Project description:Fibrolamellar carcinoma (FLC) is a liver cancer of adolescents and young adults defined by fusion of the DNAJB1 heat shock protein and protein kinase A (PKA) catalytic subunit (DNAJB1-PRKACA). The resulting chimeric protein has increased kinase activity and is essential for FLC xenograft growth. However, the critical oncogenic pathways controlled by DNAJB1-PRKACA have not been defined. Here, we explored this question by studying patient-derived FLC models and engineered systems and analyzing patient samples. We show that the core function of DNAJB1-PRKACA is the direct phosphorylation and inactivation of the Salt-inducible kinases. This leads to deregulation of the CRTC2 co-activator and p300 acetyltransferase, resulting in transcriptional reprogramming and global increases in histone acetylation necessary for malignant growth. Our studies establish a central oncogenic mechanism of DNAJB1-PRKACA and suggest opportunities for therapeutic targeting of CRTC2/p300 in FLC. Notably, these findings link this signature fusion oncoprotein of a rare cancer type to more common cancer gene alterations involving the STK11 tumor suppressor and GNAS oncogene, which also function via SIK suppression.
Project description:Autophagy as a conserved degradation and recycling machinery is important in normal development and physiology, and defects in this process are linked to many kinds of disease. Because too much or too little autophagy can be detrimental, the process must be tightly regulated both temporally and in magnitude. The transcriptional induction and repression of the autophagy-related (ATG) genes is one crucial aspect of this regulation, but the transcriptional regulators that modulate autophagy are not well characterized. In this study, we identified Pho23 as a master transcriptional repressor for autophagy, with transcriptome profiling revealing that ATG9 is one of the key target genes. Physiological studies with a PHO23 null mutant, or with strains expressing modulated levels of Atg9, demonstrate a critical role of this protein as a regulator of autophagosome formation frequency; Atg9 protein levels correlate with the number of autophagosomes generated upon autophagy induction, and the level of autophagy activity. WT yeast and pho23 deletion mutants were grown under nutrient rich or nitrogen starvation conditions; gene expression was quantified across these 4 samples.
Project description:Brassinosteroids (BRs) regulate plant growth, development and stress responses by activating the core transcription factor BRI1-EMS-SUPPRESSOR1 (BES1). The E3 Ubiquitin ligase(s) that modify BES1 for autophagy-mediated degradation remain to be fully defined. In this study, we identified an F-box family E3 ubiquitin ligase termed BES1-ASSOCIATED F-BOX1 (BAF1). BAF1 interacts with and ubiquitinates BES1. Accordingly, BES1 stability and protein levels were reduced in BAF1 overexpression plants but increased in a baf1 loss-of-function mutant and in BAF1-DF (BAF1 with F-box deleted, dominant-negative form) overexpression lines. Selective autophagy of BES1, but not bulk autophagy, was significantly compromised in the baf1 mutant under sucrose starvation. BES1 degradation mediated by BAF1 could be blocked through autophagy but not proteasome inhibitors, suggesting that BAF1 mediates BES1 degradation largely through autophagy. baf1 and BAF1-DF overexpression plants had increased BR-regulated growth but were sensitive to long-term sucrose starvation, while BAF1 overexpression plants had decreased BR-regulated growth but were highly tolerant of sucrose starvation. Our results not only established BAF1 as a novel E3 ubiquitin ligase that targets BES1 for degradation through selective autophagy pathway, but also revealed a mechanism for plants to reduce growth during sucrose starvation by targeting this central growth regulator.
Project description:Autophagy is a catabolic pathway that maintains cellular homeostasis under various stress conditions, including nutrient-deprived conditions. To elevate autophagic flux to a sufficient level under stress conditions, transcriptional activation of autophagy genes occurs to replenish autophagy components. Here, using combination of RNA-seq, ATAC-seq and ChIP-seq, we demonstrated found that plant homeodomain finger protein 20 (Phf20PHF20), which is an epigenetic reader possessing methyl binding activity, plays a key role in controlling the expression of autophagy genes. PHF20 activates autophagy genes through enhancer activation via H3K36me2 binding activity as an epigenetic reader and that our findings emphasize the importance of nuclear regulation of autophagy.
Project description:Autophagy is a catabolic pathway that maintains cellular homeostasis under various stress conditions, including nutrient-deprived conditions. To elevate autophagic flux to a sufficient level under stress conditions, transcriptional activation of autophagy genes occurs to replenish autophagy components. Here, using combination of RNA-seq, ATAC-seq and ChIP-seq, we demonstrated found that plant homeodomain finger protein 20 (Phf20PHF20), which is an epigenetic reader possessing methyl binding activity, plays a key role in controlling the expression of autophagy genes. PHF20 activates autophagy genes through enhancer activation via H3K36me2 binding activity as an epigenetic reader and that our findings emphasize the importance of nuclear regulation of autophagy.
Project description:Autophagy is a catabolic pathway that maintains cellular homeostasis under various stress conditions, including nutrient-deprived conditions. To elevate autophagic flux to a sufficient level under stress conditions, transcriptional activation of autophagy genes occurs to replenish autophagy components. Here, using combination of RNA-seq, ATAC-seq and ChIP-seq, we demonstrated found that plant homeodomain finger protein 20 (Phf20PHF20), which is an epigenetic reader possessing methyl binding activity, plays a key role in controlling the expression of autophagy genes. PHF20 activates autophagy genes through enhancer activation via H3K36me2 binding activity as an epigenetic reader and that our findings emphasize the importance of nuclear regulation of autophagy.