Project description:Transcriptome analysis of ESCs treated with a proteosome inhibitor (MG132 1μM), with our without ERK activity to measure Erk-dependent changes in transcriptome regulation
Project description:The series of events that allows for the conversion of adherent epithelial cells into migratory cells is collectively known as epithelial-mesenchymal transition (EMT). EMT is involved in triggering neural crest migration during development and in the pathogenesis of diseases, such as cancer metastasis. Whereas Erk signalling is known to be essential for EMT, its influence on the epigenetic and transcriptional programme underlying EMT is poorly understood. Here, using a comprehensive genome-wide analysis of H3K27ac mark and gene expression in primary mammary epithelial cells undergoing EMT, we found that Erk signalling is essential for the epigenetic reprogramming underlying hallmark gene expression and phenotypic changes of EMT. We found that the chemical inhibition of Erk signalling during EMT prevents loss and gain of H3K27ac mark at regulatory regions of epithelial and mesenchymal genes, respectively, and results in a transcriptome and epigenome closer to those of epithelial cells. Further computational analyses identified a distinct set of transcription factor motifs enriched at distal regulatory regions that are epigenetically remodelled by Erk signalling. Altogether, our study reveal an Erk-dependent epigenetic remodelling of distal regulatory elements that results in a gene expression programme that is essential for driving EMT.
Project description:Mutational activation of the KRAS oncogene is a major genetic driver of pancreatic ductal adenocarcinoma (PDAC) growth. KRAS-dependent PDAC growth is mediated primarily through persistent activation of the RAF-MEK-ERK mitogen-activated protein kinase (MAPK) cascade, one of the most extensively studied cancer signaling networks. While substrates of RAF and MEK kinases are highly restricted, ERK1/2 has been attributed to over 1,000 substrates. In this study, we used the highly selective ERK1/2 inhibitor, SCH772984, and proteomic and phosphoproteomic analyses to extend the repertoire of ERK-dependent phosphosites and phosphoproteins in PDAC. We validated the specificity of SCH772984 in our cell lines using multiplexed inhibitor beads coupled with mass spectrometry (MIB/MS). We then performed phosphoproteomics and global proteomics in a panel of PDAC cell lines and identified 5,117 ERK-dependent phosphosites on 2,252 proteins, of which 88% and 67%, respectively, were not previously associated with ERK. We then utilized our recently annotated serine/threonine kinome motif database to dissect the phosphoproteome and reveal an expansive ERK-regulated kinase network. We found that ERK- and immediate downstream kinase RSK-substrate motifs predominated after one hour of ERK inhibition, whereas cell cycle regulatory cyclin-dependent kinase motifs predominated by 24 h, reflecting a highly dynamic ERK-dependent phosphoproteome. We find compensatory activation of HIPK, CLK, PKN, PAK, and DYRK family kinases. Finally, using the genome-wide CRISPR-Cas9 dataset in the Cancer Dependency Map portal (DepMap), we determined that approximately 18% of ERK dependent phosphoproteins are essential for pancreatic cancer growth, and these are enriched in nuclear proteins. Together, our findings provide a system-wide profile of the mechanistic basis for ERK-driven pancreatic cancer growth.
Project description:Studies were undertaken to determine whether oscillatory behavior in the extracellular signal regulated kinase (ERK) pathway results in unique gene regulation patterns. Microarray analysis was performed on three subcloned populations of human keratinocytes with distinct ERK signaling/oscillation phenotypes. Microarray analysis identified 45 genes that overlapped between 2 subclones with oscillation phenotypes but not in the subclone which is non-oscillatory. Transcription factor networks revealed a role for MED1 in mediating ERK oscillation-dependent gene expression, which was confirmed with Western blot analysis. Further experimentation confirmed a role for p38 in the mediation of MED1 phosphorylation and ERK oscillatory behavior. hTERT-immortalized normal human keratinocytes (provided by Dr. Jerry Shay, The University of Texas Southwestern Medical Center) were stably transfected with ERK1-green fluorescent protein chimera and stable subclones were isolated with distinct ERK activation/oscillation patterns: Clone #1 exhibits transient ERK activation with ligand activation but does not oscillate; Clone #2 exhibits persistent ERK oscillations that are dependent on ligand activation; and Clone #3 exhibits spontaneous ERK oscillations in the absence of ligand activation.
Project description:Mutational activation of the KRAS oncogene is a major genetic driver of pancreatic ductal adenocarcinoma (PDAC) growth. KRAS-dependent PDAC growth is mediated primarily through persistent activation of the RAF-MEK-ERK mitogen-activated protein kinase (MAPK) cascade, one of the most extensively studied cancer signaling networks. While substrates of RAF and MEK kinases are highly restricted, ERK1/2 has been attributed to over 1,000 substrates. In this study, we used the highly selective ERK1/2 inhibitor, SCH772984, and proteomic and phosphoproteomic analyses to extend the repertoire of ERK-dependent phosphosites and phosphoproteins in PDAC. We validated the specificity of SCH772984 in our cell lines using multiplexed inhibitor beads coupled with mass spectrometry (MIB/MS). We then performed phosphoproteomics and global proteomics in a panel of PDAC cell lines and identified 5,117 ERK-dependent phosphosites on 2,252 proteins, of which 88% and 67%, respectively, were not previously associated with ERK. We then utilized our recently annotated serine/threonine kinome motif database to dissect the phosphoproteome and reveal an expansive ERK-regulated kinase network. We found that ERK- and immediate downstream kinase RSK-substrate motifs predominated after one hour of ERK inhibition, whereas cell cycle regulatory cyclin-dependent kinase motifs predominated by 24 h, reflecting a highly dynamic ERK-dependent phosphoproteome. We find compensatory activation of HIPK, CLK, PKN, PAK, and DYRK family kinases. Finally, using the genome-wide CRISPR-Cas9 dataset in the Cancer Dependency Map portal (DepMap), we determined that approximately 18% of ERK dependent phosphoproteins are essential for pancreatic cancer growth, and these are enriched in nuclear proteins. Together, our findings provide a system-wide profile of the mechanistic basis for ERK-driven pancreatic cancer growth.
Project description:Mutational activation of the KRAS oncogene is a major genetic driver of pancreatic ductal adenocarcinoma (PDAC) growth. KRAS-dependent PDAC growth is mediated primarily through persistent activation of the RAF-MEK-ERK mitogen-activated protein kinase (MAPK) cascade, one of the most extensively studied cancer signaling networks. While substrates of RAF and MEK kinases are highly restricted, ERK1/2 has been attributed to over 1,000 substrates. In this study, we used the highly selective ERK1/2 inhibitor, SCH772984, and proteomic and phosphoproteomic analyses to extend the repertoire of ERK-dependent phosphosites and phosphoproteins in PDAC. We validated the specificity of SCH772984 in our cell lines using multiplexed inhibitor beads coupled with mass spectrometry (MIB/MS). We then performed phosphoproteomics and global proteomics in a panel of PDAC cell lines and identified 5,117 ERK-dependent phosphosites on 2,252 proteins, of which 88% and 67%, respectively, were not previously associated with ERK. We then utilized our recently annotated serine/threonine kinome motif database to dissect the phosphoproteome and reveal an expansive ERK-regulated kinase network. We found that ERK- and immediate downstream kinase RSK-substrate motifs predominated after one hour of ERK inhibition, whereas cell cycle regulatory cyclin-dependent kinase motifs predominated by 24 h, reflecting a highly dynamic ERK-dependent phosphoproteome. We find compensatory activation of HIPK, CLK, PKN, PAK, and DYRK family kinases. Finally, using the genome-wide CRISPR-Cas9 dataset in the Cancer Dependency Map portal (DepMap), we determined that approximately 18% of ERK dependent phosphoproteins are essential for pancreatic cancer growth, and these are enriched in nuclear proteins. Together, our findings provide a system-wide profile of the mechanistic basis for ERK-driven pancreatic cancer growth.
Project description:Aberrant activation of the ERK signaling pathway triggers a protective anticancer response characterized by stable growth arrest and activation of tumor suppressors called cellular senescence. Pancreatic adenocarcinomas (PDAC) often possess mutations in K-Ras that activate the ERK pathway. Pancreatic intraepithelial neoplasia of low degree display high levels of phospho-ERK consistent with senescence acting as a barrier for malignant transformation. However, advanced lesions downregulate phospho-ERK levels circumventing the senescence barrier. Restoring ERK hyperactivation in PDAC using an activated allele of the kinase RAF, leads to ERK-dependent growth arrest with senescence biomarkers. Phosphoproteomics analysis of ERK-dependent senescence in PDAC revealed a decrease in several nucleolar phosphoproteins suggesting that high levels of ERK lead to senescence via nucleolar stress. Consistent with this explanation, ERK-dependent senescent cells displayed intranucleolar foci containing RNA polymerase I. Combining ribosome biogenesis inhibitors with ERK hyperactivation reinforced the senescence response of PDAC cells. The drug cocktail FOLFIRINOX, currently the best treatment for PDAC, also triggered ERK hyperactivation and nucleolar stress characterized by nucleolar foci, solid amyloid aggregates and a decrease in 5.8S and 28S rRNAs. We thus suggest that drugs targeting ribosome biogenesis can improve the senescence anticancer response in pancreatic cancer.