3 years ago

p66Shc deficiency enhances CXCR4 and CCR7 recycling in CLL B cells by facilitating their dephosphorylation-dependent release from β-arrestin at early endosomes

Gianpietro Semenzato, Pier Giuseppe Pelicci, Alessandra Gamberucci, Veronica Martini, Laura Patrussi, Federica Frezzato, Francesca Cattaneo, Livio Trentin, Nagaja Capitani, Cosima T. Baldari, Andrea Visentin, Noemi Manganaro, Mario M. D’Elios
Neoplastic cell traffic abnormalities are central to the pathogenesis of chronic lymphocytic leukemia (CLL). Enhanced CXC chemokine receptor-4 (CXCR4) and chemokine receptor-7 (CCR7) recycling contributes to the elevated surface levels of these receptors on CLL cells. Here we have addressed the role of p66Shc, a member of the Shc family of protein adaptors the expression of which is defective in CLL cells, in CXCR4/CCR7 recycling. p66Shc reconstitution in CLL cells reduced CXCR4/CCR7 recycling, lowering their surface levels and attenuating B-cell chemotaxis, due to their accumulation in Rab5+ endosomes as serine-phosphoproteins bound to β-arrestin. This results from the ability of p66Shc to inhibit Ca2+ and PP2B-dependent CXCR4/CCR7 dephosphorylation and β-arrestin release. We also show that ibrutinib, a Btk inhibitor that promotes leukemic cell mobilization from lymphoid organs, reverses the CXCR4/CCR7 recycling abnormalities in CLL cells by increasing p66Shc expression. These results, identifying p66Shc as a regulator of CXCR4/CCR7 recycling in B cells, underscore the relevance of its deficiency to CLL pathogenesis and provide new clues to the mechanisms underlying the therapeutic effects of ibrutinib.

Publisher URL: https://www.nature.com/articles/s41388-017-0066-2

DOI: 10.1038/s41388-017-0066-2

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