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An extracellular RTK sequence motif is associated with selective STAT signaling a–d Phosphorylation of STAT5a, STAT5b and STAT3 in COS-7 cells expressing EGFR, ErbB2, or ErbB3. Activating STAT5 and STAT3 phosphorylation was detected with antibodies specific for pY694/699 and pY705, respectively. Cells were treated with NRG-1 or EGF. Panels b and d depict densitometric quantification of n = 4 independent experiments. Mack-Skillings two-way ANOVA. e, f Densitometric quantification of data from Western analyses of STAT5a and STAT5b phosphorylation (on Y694/699) in COS-7 cells expressing the indicated RTK constructs. Cells were treated with 1% FCS. Representative Western blots are shown in Supplementary Fig. 10a, b. n = 5 independent experiments. Mack-Skillings two-way ANOVA. g, h JM-a- and JM-b-like sequence motifs in the eJM domain of RTKs. i, j Densitometric quantification of data from Western analyses of STAT5a and STAT5b phosphorylation (on Y694/699) in COS-7 cells expressing the indicated wild-type (wt) or mutant ErbB4 constructs. Cells were treated with NRG-1. Representative Western blots are shown in Supplementary Fig. 10c, d. n = 3–5 independent experiments. One way ANOVA. Benjamini, Krieger and Yekutieli adjusted P-values. k Position of residues H631 and D632 in the ErbB4 model structure. A compilation model of the ErbB4 ectodomain homodimer X-ray structure with bound NRG-1 (PDB ID: 3U7U) and NMR structure of ErbB4 transmembrane dimer (PDB ID: 2LCX) is shown. The location of the key residues H631 and D632 are indicated in atom fill. The borders of plasma membrane are marked with grey horizontal lines. In the boxplots the line represents the median, the box the interquartile range and whiskers the whole range of values. Source data are provided as a Source Data file.
Source publication
The ErbB4 receptor isoforms JM-a and JM-b differ within their extracellular juxtamembrane (eJM) domains. Here, ErbB4 isoforms are used as a model to address the effect of structural variation in the eJM domain of receptor tyrosine kinases (RTK) on downstream signaling. A specific JM-a-like sequence motif is discovered, and its presence or absence (...
Citations
Tumor growth requires elevated ribosome biogenesis. Targeting ribosomes is an important strategy for cancer therapy. The ribosome inhibitor, homoharringtonine (HHT), is used for the clinical treatment of leukemia, yet it is ineffective for the treatment of solid tumors, the reasons for which remain unclear. Here we show that Snail1, a key factor in the regulation of epithelial-to-mesenchymal transition, plays a pivotal role in cellular surveillance response upon ribotoxic stress. Mechanistically, ribotoxic stress activates the JNK-USP36 signaling to stabilize Snail1 in the nucleolus, which facilitates ribosome biogenesis and tumor cell survival. Furthermore, we show that HHT activates the JNK-USP36-Snail1 axis in solid tumor cells, but not in leukemia cells, resulting in solid tumor cell resistance to HHT. Importantly, a combination of HHT with the inhibition of the JNK-USP36-Snail1 axis synergistically inhibits solid tumor growth. Together, this study provides a rationale for targeting the JNK-USP36-Snail1 axis in ribosome inhibition-based solid tumor therapy.
The growth factor Neuregulin-1 (NRG-1) regulates myocardial growth and is currently under clinical investigation as a treatment for heart failure. Here, we demonstrate in several in vitro and in vivo models that STAT5b mediates NRG-1/EBBB4-stimulated cardiomyocyte growth. Genetic and chemical disruption of the NRG-1/ERBB4 pathway reduces STAT5b activation and transcription of STAT5b target genes Igf1, Myc, and Cdkn1a in murine cardiomyocytes. Loss of Stat5b also ablates NRG-1-induced cardiomyocyte hypertrophy. Dynamin-2 is shown to control the cell surface localization of ERBB4 and chemical inhibition of Dynamin-2 downregulates STAT5b activation and cardiomyocyte hypertrophy. In zebrafish embryos, Stat5 is activated during NRG-1-induced hyperplastic myocardial growth, and chemical inhibition of the Nrg-1/Erbb4 pathway or Dynamin-2 leads to loss of myocardial growth and Stat5 activation. Moreover, CRISPR/Cas9-mediated knockdown of stat5b results in reduced myocardial growth and cardiac function. Finally, the NRG-1/ERBB4/STAT5b signaling pathway is differentially regulated at mRNA and protein levels in the myocardium of patients with pathological cardiac hypertrophy as compared to control human subjects, consistent with a role of the NRG-1/ERBB4/STAT5b pathway in myocardial growth.
The growth factor neuregulin-1 (NRG-1) regulates hypertrophic and hyperplastic myocardial growth and is currently under clinical investigation as a treatment for heart failure. We have previously demonstrated that an isoform of the NRG-1 receptor ERBB4 (ERBB4 JM-b) expressed in cardiomyocytes selectively regulates the activation of STAT5b. To explore the role of STAT5b in NRG-1/EBBB4 mediated cardiomyocyte growth, several in vitro and in vivo models were utilized. The downregulation of NRG-1/ERBB4 signaling consistently reduced STAT5b activation and transcription of STAT5b target genes Igf1, Myc and Cdkn1a in murine in vitro and in vivo models of myocardial growth. Stat5b knock-down in primary cardiomyocytes ablated NRG-1-induced cardiomyocyte hypertrophy. Stat5b was activated during NRG-1-induced hyperplastic myocardial growth and chemical inhibition of the Nrg-1/Erbb4 pathway led to the loss of myocardial growth and Stat5 activation in zebrafish embryos. Moreover, CRISPR/Cas9-mediated knock-down of stat5b in zebrafish embryos resulted in reduced myocardial growth and heart failure as indicated by reduced ventricular ejection fraction. Dynamin-2 was discovered to control the cell surface localization of ERBB4 and the chemical inhibition of dynamin-2 downregulated NRG-1/ERBB4/STAT5b signaling in models of hypertrophic and hyperplastic myocardial growth. Finally, the activation of the NRG-1/ERBB4/STAT5b signaling pathway was explored in clinical samples representing pathological cardiac hypertrophy. The NRG-1/ERBB4/STAT5b signaling pathway was differentially regulated both at the mRNA and protein levels in the myocardium of patients with pathological cardiac hypertrophy as compared to myocardium of control subjects. These results establish the role for STAT5b, and dynamin-2 in NRG-1/ERBB4-mediated myocardial growth.
