Proteasome regulation by reversible tyrosine phosphorylation at the membrane
- 18 February 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in Oncogene
- Vol. 40 (11), 1942-1956
- https://doi.org/10.1038/s41388-021-01674-z
Abstract
Reversible phosphorylation has emerged as an important mechanism for regulating 26S proteasome function in health and disease. Over 100 phospho-tyrosine sites of the human proteasome have been detected, and yet their function and regulation remain poorly understood. Here we show that the 19S subunit Rpt2 is phosphorylated at Tyr439, a strictly conserved residue within the C-terminal HbYX motif of Rpt2 that is essential for 26S proteasome assembly. Unexpectedly, we found that Y439 phosphorylation depends on Rpt2 membrane localization mediated by its N-myristoylation. Multiple receptors tyrosine kinases can trigger Rpt2–Y439 phosphorylation by activating Src, a N-myristoylated tyrosine kinase. Src directly phosphorylates Rpt2–Y439 in vitro and negatively regulates 26S proteasome activity at cellular membranes, which can be reversed by the membrane-associated isoform of protein tyrosine phosphatase nonreceptor type 2 (PTPN2). In H1975 lung cancer cells with activated Src, blocking Rpt2–Y439 phosphorylation by the Y439F mutation conferred partial resistance to the Src inhibitor saracatinib both in vitro and in a mouse xenograft tumor model, and caused significant changes of cellular responses to saracatinib at the proteome level. Our study has defined a novel mechanism involved in the spatial regulation of proteasome function and provided new insights into tyrosine kinase inhibitor-based anticancer therapies.Funding Information
- National Natural Science Foundation of China (31671391, 31870762, 31671039, 91953103)
- Natural Science Foundation of Zhejiang Province (LR18C050001)
- U.S. Department of Health & Human Services | NIH | National Institute of General Medical Sciences (R01GM074830)
- Ministry of Science and Technology of the People’s Republic of China (2016YF0501000)
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