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Activation of the E3 ligase Cbl by Neutrophil Cathepsin G Impairs CXC chemokine receptor 4 Signaling in Cardiomyocyte Degeneration.
Author(s) -
Shukla Sanket,
Sikder Kunal,
Sarkar Amrita,
Liu Weijing,
Rafiq Khadija
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.614.19
Subject(s) - microbiology and biotechnology , ubiquitin ligase , chemistry , inflammation , protein degradation , lactacystin , cxc chemokine receptors , ubiquitin , signal transduction , mg132 , chemokine , cancer research , proteasome , chemokine receptor , biology , immunology , proteasome inhibitor , biochemistry , gene
Objective Inflammatory cells and their proteases contribute to tissue repair at the site of inflammation. Although beneficial in the early stage, excessive inflammation leads to cell death and tissue damage. Increasing evidence demonstrates the role of inflammatory cells and their proteases in cardiac remodeling during the progression to heart failure; however the mechanisms by which inflammation contribute to myocyte death and subsequent alteration in the geometry and mechanical properties of the heart are still largely unknown. Therefore, we hypothesized that neutrophil‐derived protease Cat.G regulates CXC chemokine receptor (CXCR) 4 protein stability and turnover in myocytes through activation of Casitas b‐lineage lymphoma (c‐Cbl), an adaptor protein with an intrinsic E3 ubiquitin ligase activity. Methods and Results We have previously shown that neutrophil serine protease Cat.G promotes cardiomyocyte death through c‐Cbl activation and interaction with tyrosine receptors that result in their ubiquitination and degradation. We next assessed whether Cbl activation was involved in CXCR4 signaling downregulation and myocyte apoptosis secondary to exposure of Cat.G. Acute stimulation with Cat.G (5 min to 30 min) induced CXCR4 phosphorylation along with its interaction with Cbl. However, chronic stimulation with Cat.G (1–4hrs) increased both CXCR4 ubiquitination and degradation. Inhibition of the ubiquitin proteasome system, with MG132 or lactacystin, or adenoviral expression of dominant negative mutant Cbl significantly reduced CXCR4 degradation induced by Cat.G. In contrast, adenoviral expression of wild type Cbl enhanced CXCR4 ubiquitination and degradation in response to Cat.G. Restoration of CXCR4 signaling, by adenoviral expression of CXCR4, attenuated CXCR4 downstream signaling downregulation, myofibril degeneration and myocyte apoptosis induced by Cat.G. Conclusion These data support a model in which neutrophil derived serine proteases promote c‐Cbl interaction with CXCR4 protein, resulting in enhanced c‐Cbl‐mediated CXCR4 protein degradation, myofibril degradation and subsequent down‐regulation of myocyte survival signaling.