Modulation of the CXC chemokine receptor 4 agonist activity of ubiquitin through C-terminal protein modification Journal Article

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Authors: Tripathi, A; Saini, V.; Marchese, A; Volkman, B. F.; Tang, W. J.; Majetschak, M
Article Title: Modulation of the CXC chemokine receptor 4 agonist activity of ubiquitin through C-terminal protein modification
Abstract: Extracellular ubiquitin has recently been described as a CXC chemokine receptor (CXCR) 4 agonist. Studies on the structure-function relationship suggested that the C-terminus of ubiquitin facilitates CXCR4 activation. It remains unknown, however, whether C-terminal processing of ubiquitin could be biologically relevant and whether modifications of the ubiquitin C-terminus can modulate CXCR4 activation. We show that C-terminal truncated ubiquitin antagonizes ubiquitin and stromal cell-derived factor (SDF)-1alpha induced effects on cell signaling and function. Reduction of cell surface expression of insulin degrading enzyme (IDE), which cleaves the C-terminal di-Gly of ubiquitin, enhances ubiquitin induced reduction of cAMP levels in BV2 and THP-1 cells, but does not influence changes in cAMP levels in response to SDF-1alpha. Reduction of cell surface IDE expression in THP-1 cells also increases the chemotactic activity of ubiquitin. As compared with native ubiquitin, C-terminal Tyr extension of ubiquitin results in reduced CXCR4 mediated effects on cellular cAMP levels and abolishes chemotactic activity. Replacement of C-terminal di-Gly of ubiquitin with di-Val or di-Arg enhances CXCR4 mediated effects on cAMP levels and the di-Arg substitution exerts increased chemotactic activity, when compared with wild type ubiquitin. The chemotactic activities of the di-Val and di-Arg mutants and their effects on cAMP levels can be antagonized with C-terminal truncated ubiquitin. These data suggest that the development of CXCR4 ligands with enhanced agonist activities is possible and that C-terminal processing of ubiquitin could constitute a biological mechanism, which regulates termination of receptor signaling.
Journal Title: Biochemistry
Volume: 52
Issue: 24
ISSN: 1520-4995; 0006-2960
Publisher: Unknown  
Journal Place: United States
Date Published: 2013
Start Page: 4184
End Page: 4192
Language: eng
DOI/URL:

10.1021/bi400254f
Notes: LR: 20151002; GR: GM075159/GM/NIGMS NIH HHS/United States; GR: GM081539/GM/NIGMS NIH HHS/United States; GR: R01 AI058072/AI/NIAID NIH HHS/United States; GR: R01 GM075159/GM/NIGMS NIH HHS/United States; GR: R01 GM081539/GM/NIGMS NIH HHS/United States; JID: 0370623; 0 (CXCR4 protein, human); 0 (CXCR4 protein, mouse); 0 (Chemokine CXCL12); 0 (Insulin); 0 (RNA, Small Interfering); 0 (Receptors, CXCR4); 0 (Ubiquitin); 42HK56048U (Tyrosine); E0399OZS9N (Cyclic AMP); NIHMS606365; OID: NLM: NIHMS606365; OID: NLM: PMC4113718; 2013/06/07 [aheadofprint]; ppublish