Project description:Understanding the structure and interplay of cellular signalling pathways is one of the great challenges in molecular biology. Boolean Networks can infer signalling networks from observations of protein activation. In situations where it is difficult to assess protein activation directly, Nested Effect Models are an alternative. They derive the network structure indirectly from downstream effects of pathway perturbations. To date, Nested Effect Models cannot resolve signalling details like the formation of signalling complexes or the activation of proteins by multiple alternative input signals. Here we introduce Boolean Nested Effect Models (B-NEM). B-NEMs combine the use of downstream effects with the higher resolution of signalling pathway structures in Boolean Networks. We show that B-NEMs accurately reconstruct signal flows in simulated data. Using B-NEM we then resolve BCR signalling via PI3K and TAK1 kinases in BL2 lymphoma cell lines. 84 BL2 cell-line samples were hybridized to HGU133+2 Affymetrix GeneChips.
Project description:Elucidating protein kinase driven signaling pathways is an important but challenging problem in cell biology. Phosphoproteomics has been used to identify many phosphorylation sites, however the spatial context of these sites within the cell is mostly unknown making it difficult to reconstruct signalling pathways. To address this problem an in vivo proximity capturing workflow was developed consisting of proximity biotinylation followed by protein cross-linking (XL-BioID). This was applied to protein kinases of the Leishmania kinetochore leading to the discovery of a novel essential kinetochore protein, KKT26. XL-BioID enabled the quantification of proximal phosphosites at the kinetochore through the cell cycle, allowing the phosphorylation state of the kinetochore to be followed during assembly. A specific inhibitor of kinetochore protein kinases KKT10/KKT19 was used to show that XL-BioID provides a spatially focussed view of protein kinase inhibition, identifying 16 inhibitor responsive proximal phosphosites, including 3 on KKT2, demonstrating the potential of this approach for discovery of in vivo kinase signalling pathways.
Project description:Understanding the structure and interplay of cellular signalling pathways is one of the great challenges in molecular biology. Boolean Networks can infer signalling networks from observations of protein activation. In situations where it is difficult to assess protein activation directly, Nested Effect Models are an alternative. They derive the network structure indirectly from downstream effects of pathway perturbations. To date, Nested Effect Models cannot resolve signalling details like the formation of signalling complexes or the activation of proteins by multiple alternative input signals. Here we introduce Boolean Nested Effect Models (B-NEM). B-NEMs combine the use of downstream effects with the higher resolution of signalling pathway structures in Boolean Networks. We show that B-NEMs accurately reconstruct signal flows in simulated data. Using B-NEM we then resolve BCR signalling via PI3K and TAK1 kinases in BL2 lymphoma cell lines.
Project description:GskA, the Dictyostelium GSK-3 orthologue, is modified and activated by the dual-specificity tyrosine kinase Zak1 and the two kinases form part of a signalling pathway that responds to extracellular cAMP. We identify potential cellular effectors for the two kinases by analysing their null mutants. There are proteins and mRNAs that are altered in abundance in only one or other of the two mutants, indicating that each kinase has some unique functions. However, proteomic and micro-array analysis respectively identified 3 proteins and 37 genes that are similarly mis-regulated in both mutant strains. The positive correlation between the array data and the proteomics data is consistent with the Zak1-GskA signalling pathway functioning by directly or indirectly regulating gene expression. The discoidin 1 genes are positively regulated by the pathway while the abundance of the H5 protein is negatively regulated. Two of the targets, H5 and discoidin 1, are well-characterised markers for early development, indicating that the Zak1-GskA pathway plays a role in development earlier than previously observed.
Project description:Developing tissues interpret dynamic changes in morphogen activity to generate cell type diversity. To quantitatively study BMP signalling dynamicsin the vertebrateneural tube, we developed a new ES cell differentiation systemtailored for growing tissues. Differentiating cellsform strikingself-organised pattern of dorsal neural tube cell typesdriven by sequential phases of BMP signalling that are observed both in vitro and in vivo.Data-driven biophysical modelling showed that thesedynamics result from coupling fast negative feedbackwithslow positive regulation of signalling bythe specification of an endogenousBMP source.Thus, in contrast to relays that propagate morphogen signalling in space, we uncover a BMP signallingrelay that operates intime. This mechanism allows rapid initial concentration-sensitive response that is robustly terminated, thereby regulating balanced sequential cell type generation.Altogether, our study provides an experimental and theoretical framework to understand how signalling dynamicsis exploited indeveloping tissues.
Project description:This randomized phase I/II clinical trial is studying the side effects and best dose of gamma-secretase/notch signalling pathway inhibitor RO4929097 when given together with vismodegib and to see how well they work in treating patients with advanced or metastatic sarcoma. Vismodegib may slow the growth of tumor cells. Gamma-secretase/notch signalling pathway inhibitor RO4929097 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving vismodegib together with gamma-secretase/notch signalling pathway inhibitor RO4929097 may be an effective treatment for sarcoma.
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.
Project description:Germline development provides the founding cells for spermatogenesis and oogenesis in males and females, respectively. Disrupted germline differentiation or compromised testis development can lead to subfertility or infertility and are strongly associated with testis cancer in humans. In mice, SRY and SOX9 induce expression of a range of genes, including Fgf9, that promote Sertoli cell differentiation and testis development. FGF9 is also thought to promote male germline differentiation but the pathway through which it signals is unknown. As FGFs signal through Mitogen-Activated Protein Kinases (MAPKs) in other tissues, we explored whether FGF9 regulates male germline development through MAPK by inhibiting either FGF or MEK1/2 signalling in fetal testis cultures from embryonic day (E)12.5, immediately after gonadal sex determination and testis cord formation, but prior to male germline commitment. Inhibition of MEK1/2 disrupted mitotic arrest, dysregulated a broad range of male germline development genes and prevented the upregulation of key male germline markers DPPA4 and DNMT3L. In contrast, when FGF signalling was inhibited, the male germline specific transcriptional program and the expression of male germline markers DPPA4 and DNMT3L were unaffected, and the germ cells entered mitotic arrest normally. While male germline development was not disrupted by FGF inhibition, a significant number of genes were commonly altered after 24h of FGF or MEK1/2 inhibition including genes involved in maintenance germline stem cells, Nodal signalling, proliferation, and germline cancer. Together, these data demonstrate a novel and essential role for MEK1/2 signalling in male germline differentiation, but a surprisingly limited role for FGF signalling. Our data strongly indicate that additional ligands act through MEK1/2 to promote male germline differentiation and highlight a need for further mechanistic understanding of male germline development.
Project description:Germline development provides the founding cells for spermatogenesis and oogenesis in males and females, respectively. Disrupted germline differentiation or compromised testis development can lead to subfertility or infertility and are strongly associated with testis cancer in humans. In mice, SRY and SOX9 induce expression of a range of genes, including Fgf9, that promote Sertoli cell differentiation and testis development. FGF9 is also thought to promote male germline differentiation but the pathway through which it signals is unknown. As FGFs signal through Mitogen-Activated Protein Kinases (MAPKs) in other tissues, we explored whether FGF9 regulates male germline development through MAPK by inhibiting either FGF or MEK1/2 signalling in fetal testis cultures from embryonic day (E)12.5, immediately after gonadal sex determination and testis cord formation, but prior to male germline commitment. Inhibition of MEK1/2 disrupted mitotic arrest, dysregulated a broad range of male germline development genes and prevented the upregulation of key male germline markers DPPA4 and DNMT3L. In contrast, when FGF signalling was inhibited, the male germline specific transcriptional program and the expression of male germline markers DPPA4 and DNMT3L were unaffected, and the germ cells entered mitotic arrest normally. While male germline development was not disrupted by FGF inhibition, a significant number of genes were commonly altered after 24h of FGF or MEK1/2 inhibition including genes involved in maintenance germline stem cells, Nodal signalling, proliferation, and germline cancer. Together, these data demonstrate a novel and essential role for MEK1/2 signalling in male germline differentiation, but a surprisingly limited role for FGF signalling. Our data strongly indicate that additional ligands act through MEK1/2 to promote male germline differentiation and highlight a need for further mechanistic understanding of male germline development.