Project description:Like all receptor tyrosine kinases (RTKs), ErbB4 signals through a canonical signaling involving phosphorylation cascades. However, ErbB4 can also signal through a non-canonical mechanism whereby the intracellular domain is released into the cytoplasm by regulated intermembrane proteolysis (RIP) and translocates to the nucleus where it regulates transcription. These different signaling mechanisms depend on the generation of alternative spliced isoforms, a RIP cleavable ErbB4-JMa and an uncleavable ErbB4-JMb. Non-canonical signaling by ErbB4-JMa has been implicated in the regulation of brain, heart, mammary gland, lung, and immune cell development. However, most studies on non-canonical ErbB4 signaling have been performed in vitro due to the lack of an adequate mouse model. We created an ErbB4-JMa specific knock out mouse and demonstrate that RIP-dependent, non-canonical signaling by ErbB4-JMa is required for the regulation of GFAP expression during cortical development. We also show that ErbB4-JMa signaling is not required for the development of the heart, mammary glands, sensory ganglia. Furthermore, we identify genes whose expression during cortical development is regulated by ErbB4, and show that the expression of two of them, CRYM and DBi, depend on ErbB4-JMa. Thus, we provide the first animal model to study the roles of non-canonical RTK in vivo.
Project description:ERBB4 is a member of the epidermal growth factor receptor (EGFR)/ERBB subfamily of receptor tyrosine kinases that regulates cellular processes including proliferation, migration and survival. ERBB4 signaling is involved in embryogenesis and homeostasis of adult tissues, but also in human pathologies such as cancer, neurological disorders and cardiovascular diseases. A mass spectrometry screen revealed guanine nucleotide exchange factor (GEF) VAV3, an activator of Rho family GTPases, as a novel ERBB4-interacting protein in breast cancer cells. The ERBB4-VAV3-interaction was confirmed by targeted mass-spectrometry, coimmunoprecipitation experiments, and further defined by demonstrating that kinase activity and tyrosine residues 1022 and 1162 of ERBB4, as well as the intact phosphotyrosine-interacting SH2 domain of VAV3 were necessary for the interaction. ERBB4 was also shown to stimulate tyrosine phosphorylation of the VAV3 activation domain, which is required for GEF activity of VAV proteins. In addition to VAV3, also the other members of the VAV family, VAV1 and VAV2 were shown to coprecipitate with ERBB4. Analyses of the effects of overexpression of dominant-negative VAV3 constructs or downregulation of VAV3 expression by shRNAs in breast cancer cells demonstrated that active VAV3 was involved in ERBB4-stimulated migration. These findings define the VAV GTPases as novel effectors of ERBB4 activity in a signaling pathway relevant for cancer cell migration.
Project description:The four members of the epidermal growth factor receptor (EGFR/ERBB) family form homo- and heterodimers which mediate ligand-specific regulation of many key cellular processes in normal and cancer tissues. While signaling through the EGFR has been extensively studied on the molecular level, signal transduction through ERBB3/ERBB4 heterodimers is less well understood. Here, we generated isogenic mouse Ba/F3 cells that express full-length and functional membrane-integrated ERBB3 and ERBB4 or ERBB4 alone, to serve as a defined cellular model for biological and phosphoproteomics analysis of ERBB3/ERBB4 signaling. ERBB3 co-expression significantly enhanced Ba/F3 cell proliferation upon neuregulin-1 (NRG1) treatment. For comprehensive signaling studies we performed quantitative mass spectrometry (MS) experiments to compare the basal ERBB3/ERBB4 cell phosphoproteome to NRG1 treatment of ERBB3/ERBB4 and ERBB4 cells. We employed a workflow comprising differential isotope labeling with mTRAQ reagents followed by chromatographic peptide separation and final phosphopeptide enrichment prior to MS analysis. Overall, we identified 9686 phosphorylation sites which could be confidently localized to specific residues. Statistical analysis of three replicate experiments revealed 492 phosphorylation sites which were significantly changed in NRG1-treated ERBB3/ERBB4 cells. Bioinformatics data analysis recapitulated regulation of mitogen-activated protein kinase and Akt pathways, but also indicated signaling links to cytoskeletal functions and nuclear biology. Comparative assessment of NRG1-stimulated ERBB4 Ba/F3 cells indicated that ERBB3 did not trigger defined signaling pathways but more broadly enhanced phosphoproteome regulation in cells expressing both receptors. In conclusion, our data provide the first global picture of ERBB3/ERBB4 signaling and provide numerous potential starting points for further mechanistic studies
Project description:Chromatin accessibility provides an important window into the regulation of gene expression. Recently, the Assay of Transposase Accessible Chromatin with sequencing (ATAC-seq) was developed to profile genome-wide chromatin accessibility. Here we applied a read-downsampling approach to call robust ATAC-seq peaks in order to profile the regions of differential chromatin accessibility of central amygdala and cortex between different experimental conditions; fear-conditioned vs. control mice and ErbB4 knock-out vs. wild-type mice.
Project description:To identify the potential target genes that were affected by the expression of ErbB4 in mouse embryonic stem cells-derived cardiomyocytes Embryonic Stem Cells-Derived Cardiomyocytes were transfected with si-ErbB4 for 48 hours
Project description:Convergent and divergent effects of two FL ERBB4 isoforms on gene expression in normal-like MCF10A mammary epithelial cells lacking endogeneous ERBB4 expression. Control vector (VEC) and ERBB4 expression MCF10A cells(CYT1 or CYT2) were serum starved for 48 hours and incubated with or without ERBB4 ligand NRG1 for 2h. RNA samples were collected and analyzed.
Project description:Convergent and divergent effects of two ICD ERBB4 isoforms on gene expression in normal-like MCF10A mammary epithelial cells lacking endogeneous ERBB4 expression. Control vector (VEC) and ERBB4 expression MCF10A cells (ICD CYT1 or CYT2) maintained in regular medium containing 10% serum, were collected and RNA samples were collected and analyzed.
Project description:Neuregulin-1 (NRG1) is a paracrine growth factor, secreted by cardiac endothelial cells (Ecs) in conditions of cardiac overload/injury. The current concept is that the cardiac effects of NRG1 are mediated by activation of ERBB4/ERBB2 receptors on cardiomyocytes. However, recent studies have shown that paracrine effects of NRG1 on fibroblasts and macrophages are equally important. Here, we hypothesize that NRG1 autocrine signaling plays a role in cardiac remodeling. We generated EC–specific Erbb4 knockout mice to eliminate endothelial autocrine ERBB4 signaling without affecting paracrine NRG1/ERBB4 signaling in the heart. We first observed no basal cardiac phenotype in these mice up to 32 weeks. We next studied these mice following transverse aortic constriction (TAC), exposure to angiotensin II (Ang II) or myocardial infarction in terms of cardiac performance, myocardial hypertrophy, myocardial fibrosis and capillary density. In general, no major differences between EC–specific Erbb4 knockout mice and control littermates were observed. However, 8 weeks following TAC both myocardial hypertrophy and fibrosis were attenuated by EC–specific Erbb4 deletion, albeit these responses were normalized after 20 weeks. Similarly, 4 weeks after Ang II treatment myocardial fibrosis was less pronounced compared to control littermates. These observations were supported by RNA-sequencing experiments on cultured endothelial cells showing that NRG1 controls the expression of various hypertrophic and fibrotic pathways. Overall, this study shows a role of endothelial autocrine NRG1/ERBB4 signaling in the modulation of hypertrophic and fibrotic responses during early cardiac remodeling. This study contributes to understanding the spatio-temporal heterogeneity of myocardial autocrine and paracrine responses following cardiac injury.
Project description:To determine the transcriptomic changes of small-molecule-induced activation of ERBB4 in heart failure, we tested the effects of the two small molecules (NRG1 and EF-1) of ERBB4 agonists on iAM (immortalized atrial cardiomyocytes) model. The transcriptional profiles of mRNA in these samples will be measured with high throughput technology. Changes in transcriptional profiles between the activation of EF-1 and NRG1 will be compared.