Homo sapiens
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA383400 | ENA |
REPOSITORIES: ENA
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Project description:The RAC1 GTPase and its effector PAK1 have been found to be overexpressed or hyperactivated in colorectal cancer (CRC), one of the most prevalent types of cancer in the world. This overexpression frequently correlates with chemoresistance and less favourable prognoses. We previously showed that the activation of RAC1/PAK1 signalling promotes a switch between the BCL6 transcriptional repressor and the STAT5 transcriptional activator at a subset of pro-proliferative gene promoters. Here we used ChIP-Seq, under conditions of pathway inhibition and stimulation, to identify the BCL6/STAT5-switch binding sites throughout the genome. Using a knowledge-driven pipeline for ChIP-Seq data analysis, we identify 3774 genomic features associated to the switch-motif, with a significant enrichment in protein-coding genes involved in DNA damage repair pathways. Stimulation of RAC1/PAK1 signalling in DLD-1 CRC cells increased the expression of these genes and significantly enhanced DNA repair in response to damage induced by alkylating agents. Our results reveal a new transcriptional reprogramming mechanism whereby the alternate binding of a repressor and an activator protein to low-affinity motifs is used to coordinate a transcriptional response to DNA damage. This mechanism may link the upregulation of the RAC1/PAK1 pathway to the chemoresistant phenotype of aggressive CRCs.
2019-04-30 | GSE97938 | GEO
Project description:In the central nervous system (CNS), myelin formation by oligodendrocytes (OLs) relies on actin dynamics. Actin polymerization supports the ensheathment step, when the OL process contacts and surrounds a selected portion of axon. While a drastic shift to actin depolymerization is then required to enable the wrapping process and the formation of a multilayered myelin sheath. Molecular mechanisms regulating this switch to actin depolymerization are not fully elucidated. P21-activated kinase 1 (PAK1), a downstream effector of Rho GTPases Rac1 and Cdc42, highly expressed in OLs, can regulate actin dynamics through its kinase activity. We found that PAK1 loss-of-function in OLs, in vivo, stimulates the wrapping and the thickening of myelin sheaths. We showed that PAK1 is highly expressed in myelinating OLs, yet in its inactive form, the one with the ability to trigger actin disassembly. Interestingly, we found that modulations of PAK1 kinase activity control actin dynamics in OLs, thereby myelin formation. Our data demonstrate that PAK1 inactivation in OLs is required for actin depolymerization and proper myelin formation, suggesting the presence of an endogenous PAK1 inhibitor in myelinating OLs. Proteomic analysis of PAK1 binding partners enabled us to identify several proteins likely to regulate its activity.
2024-06-03 | PXD044344 | Pride
Project description:Interleukin 9 (IL-9) is a γc-family cytokine that is highly produced by T-helper 9 (Th9) cells and regulates a range of immune responses, including allergic inflammation. Here we show that IL-2–JAK3–STAT5 signaling is required for Th9 differentiation, with critical STAT5 binding sites in the Il9 (the gene encoding IL-9) promoter. IL-2 also inhibited B cell lymphoma 6 (BCL6) expression, and over- expression of BCL6 impaired Th9 differentiation. In contrast to IL-2, IL-21 induced BCL6 and diminished IL-9 expression in wild-type but not Bcl6−/− cells, whereas Th9 differentiation was increased in Il21−/− or Il21r−/− T cells. Interestingly, BCL6 bound in proximity to many STAT5 and STAT6 binding sites, including at the Il9 promoter. Moreover, there was increased BCL6 and decreased STAT binding at this site in cells treated with blocking antibodies to IL-2 and the IL-2 receptor, suggesting a possible BCL6–STAT5 binding competition that influences IL-9 production. BCL6 binding was also increased when cells were Th9-differentiated in the presence of IL-21. Thus, our data reveal not only direct IL-2 effects via STAT5 at the Il9 gene, but also opposing actions of IL-2 and IL-21 on BCL6 expression, with increased BCL6 expression inhibiting IL-9 production. These data suggest a model in which increasing BCL6 expression decreases efficient Th9 differentiation, indicating possible distinctive approaches for controlling this process. Genome-wide transcription factors mapping and binding of STAT5B and STAT6 in mouse polarized Th9 cells treated with or without blocking antibodies to IL-2 (anti-IL-2). RNA-Seq is conducted in WT and Il2-/- mice.
2014-02-20 | E-GEOD-41317 | biostudies-arrayexpress
Project description:Sex-dependent pituitary growth hormone (GH) secretory patterns determine the sex-biased expression of >1,000 genes in mouse and rat liver, affecting lipid and drug metabolism, inflammation and disease. A fundamental biological question is how robust differential expression can be achieved for hundreds of sex-biased genes simply based on the GH input signal pattern: pulsatile GH stimulation in males vs. near-continuous GH exposure in females. STAT5 is an essential transcriptional mediator of the sex-dependent effects of GH in the liver, but the mechanisms that underlie its sex-dependent actions are obscure. Here we elucidate the dynamic, sex-dependent binding of STAT5 and the GH/STAT5-regulated repressor BCL6 to mouse liver chromatin, revealing the counteractive interplay between these two regulators of liver sex-specificity. Our findings establish a close correlation between sex-dependent STAT5 binding and sex-biased target gene expression. Moreover, sex-dependent STAT5 binding correlated positively with sex-biased DNase hypersensitivity and H3-K4me1 and H3-K4me3 (activating) marks, correlated negatively with sex-biased H3-K27me3 (repressive) marks, and was associated with sex-differentially enriched motifs for HNF6/CDP factors. Importantly, BCL6 binding was preferentially associated with repression of female-biased STAT5 targets in male liver. Furthermore, BCL6 and STAT5 common targets but not BCL6 unique targets showed strong enrichment for lipid and drug metabolism. These findings provide a comprehensive, genome-wide view of the mechanisms whereby these two GH-regulated transcription factors establish and maintain sex differences affecting liver physiology and disease. The approaches used here to characterize sex-dependent STAT5 and BCL6 binding can be applied to other condition-specific regulatory factors and binding sites and their interplay with co-operative chromatin-binding factors. Mouse livers were excised from individual male and female mice killed at either a peak of STAT5 binding activity, or during the growth hormone (GH) interpulse interval, when STAT5 activity is either low (females) or essentially undetectable (males). Sonicated, cross-linked liver nuclear chromatin was then used to identify STAT5 binding sites by ChIP-Seq.
2011-12-18 | E-GEOD-31578 | biostudies-arrayexpress
Project description:Interleukin 9 (IL-9) is a γc-family cytokine that is highly produced by T-helper 9 (Th9) cells and regulates a range of immune responses, including allergic inflammation. Here we show that IL-2–JAK3–STAT5 signaling is required for Th9 differentiation, with critical STAT5 binding sites in the Il9 (the gene encoding IL-9) promoter. IL-2 also inhibited B cell lymphoma 6 (BCL6) expression, and over- expression of BCL6 impaired Th9 differentiation. In contrast to IL-2, IL-21 induced BCL6 and diminished IL-9 expression in wild-type but not Bcl6−/− cells, whereas Th9 differentiation was increased in Il21−/− or Il21r−/− T cells. Interestingly, BCL6 bound in proximity to many STAT5 and STAT6 binding sites, including at the Il9 promoter. Moreover, there was increased BCL6 and decreased STAT binding at this site in cells treated with blocking antibodies to IL-2 and the IL-2 receptor, suggesting a possible BCL6–STAT5 binding competition that influences IL-9 production. BCL6 binding was also increased when cells were Th9-differentiated in the presence of IL-21. Thus, our data reveal not only direct IL-2 effects via STAT5 at the Il9 gene, but also opposing actions of IL-2 and IL-21 on BCL6 expression, with increased BCL6 expression inhibiting IL-9 production. These data suggest a model in which increasing BCL6 expression decreases efficient Th9 differentiation, indicating possible distinctive approaches for controlling this process.
2014-02-20 | GSE41317 | GEO
Project description:The purpose of the study was to identify new PAK1 targets in response to ionizing radiation with putative role in the DNA damage response. We examined the effect of IR on the gene expression patterns in the murine embryonic fibroblasts with or without Pak1 using microarray. Differentially expressed transcripts were identified using Gene Spring GX 10.0.2. The samples used were Wild type, Pak1 knock out, Wild type treated with ionizing radiation and Pak1 knock out treated with ionizing radiation. Triplicates of each sample type were used for analysis.
2016-07-03 | E-GEOD-47503 | biostudies-arrayexpress
Project description:Sex-dependent pituitary growth hormone (GH) secretory patterns determine the sex-biased expression of >1,000 genes in mouse and rat liver, affecting lipid and drug metabolism, inflammation and disease. A fundamental biological question is how robust differential expression can be achieved for hundreds of sex-biased genes simply based on the GH input signal pattern: pulsatile GH stimulation in males vs. near-continuous GH exposure in females. STAT5 is an essential transcriptional mediator of the sex-dependent effects of GH in the liver, but the mechanisms that underlie its sex-dependent actions are obscure. Here we elucidate the dynamic, sex-dependent binding of STAT5 and the GH/STAT5-regulated repressor BCL6 to mouse liver chromatin, revealing the counteractive interplay between these two regulators of liver sex-specificity. Our findings establish a close correlation between sex-dependent STAT5 binding and sex-biased target gene expression. Moreover, sex-dependent STAT5 binding correlated positively with sex-biased DNase hypersensitivity and H3-K4me1 and H3-K4me3 (activating) marks, correlated negatively with sex-biased H3-K27me3 (repressive) marks, and was associated with sex-differentially enriched motifs for HNF6/CDP factors. Importantly, BCL6 binding was preferentially associated with repression of female-biased STAT5 targets in male liver. Furthermore, BCL6 and STAT5 common targets but not BCL6 unique targets showed strong enrichment for lipid and drug metabolism. These findings provide a comprehensive, genome-wide view of the mechanisms whereby these two GH-regulated transcription factors establish and maintain sex differences affecting liver physiology and disease. The approaches used here to characterize sex-dependent STAT5 and BCL6 binding can be applied to other condition-specific regulatory factors and binding sites and their interplay with co-operative chromatin-binding factors.
2011-12-18 | GSE31578 | GEO
Project description:The purpose of the study was to identify new PAK1 targets in response to ionizing radiation with putative role in the DNA damage response. We examined the effect of IR on the gene expression patterns in the murine embryonic fibroblasts with or without Pak1 using microarray.
2016-01-01 | GSE47503 | GEO
Project description:Dynamic interactions between RhoA and Rac1, members of the Rho small GTPase family, play a vital role in the control of cell migration. Using predictive mathematical modelling and experimental validation in MDA-MB-231 mesenchymal breast cancer cells, we show that Rac1 and RhoA interactions via the PAK-family kinases can produce bistable, switch-like responses to a graded PAK inhibition. Using a small chemical inhibitor of PAK we confirm the model conjecture demonstrating that cellular RhoA and Rac activation levels respond in a bistable manner to PAK inhibition where for a given inhibition level these levels are high or low depending on the history of the system. Consequently, we show that downstream signalling, actin dynamics and cell migration also behave in a bistable fashion, displaying abrupt switches and hysteresis in response to PAK inhibition. In summary, our results demonstrate that PAK is a critical component in the Rac1-RhoA inhibitory crosstalk that mediates bistable GTPase activity and cell migration switches.
2017-03-29 | MSV000080751 | MassIVE
Project description:Dynamic interactions between RhoA and Rac1, members of the Rho small GTPase family, play a vital role in the control of cell migration. Using predictive mathematical modelling and experimental validation in MDA-MB-231 mesenchymal breast cancer cells, we show that Rac1 and RhoA interactions via the PAK-family kinases can produce bistable, switch-like responses to a graded PAK inhibition. Using a small chemical inhibitor of PAK we confirm the model conjecture demonstrating that cellular RhoA and Rac activation levels respond in a bistable manner to PAK inhibition where for a given inhibition level these levels are high or low depending on the history of the system. Consequently, we show that downstream signalling, actin dynamics and cell migration also behave in a bistable fashion, displaying abrupt switches and hysteresis in response to PAK inhibition. In summary, our results demonstrate that PAK is a critical component in the Rac1-RhoA inhibitory crosstalk that mediates bistable GTPase activity and cell migration switches.
2016-12-23 | PXD003213 | Pride