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Peng WY, Abere B, Shi H, Toland S, Smithgall TE, Moore PS, Chang Y. Membrane-bound Merkel cell polyomavirus middle T protein constitutively activates PLCγ1 signaling through Src-family kinases. Proc Natl Acad Sci U S A 2023; 120:e2316467120. [PMID: 38079542 PMCID: PMC10740393 DOI: 10.1073/pnas.2316467120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/11/2023] [Indexed: 12/18/2023] Open
Abstract
Merkel cell polyomavirus (MCV or MCPyV) is an alphapolyomavirus causing human Merkel cell carcinoma and encodes four tumor (T) antigen proteins: large T (LT), small tumor (sT), 57 kT, and middle T (MT)/alternate LT open reading frame proteins. We show that MCV MT is generated as multiple isoforms through internal methionine translational initiation that insert into membrane lipid rafts. The membrane-localized MCV MT oligomerizes and promiscuously binds to lipid raft-associated Src family kinases (SFKs). MCV MT-SFK interaction is mediated by a Src homology (SH) 3 recognition motif as determined by surface plasmon resonance, coimmunoprecipitation, and bimolecular fluorescence complementation assays. SFK recruitment by MT leads to tyrosine phosphorylation at a SH2 recognition motif (pMTY114), allowing interaction with phospholipase C gamma 1 (PLCγ1). The secondary recruitment of PLCγ1 to the SFK-MT membrane complex promotes PLCγ1 tyrosine phosphorylation on Y783 and activates the NF-κB inflammatory signaling pathway. Mutations at either the MCV MT SH2 or SH3 recognition sites abrogate PLCγ1-dependent activation of NF-κB signaling and increase viral replication after MCV genome transfection into 293 cells. These findings reveal a conserved viral targeting of the SFK-PLCγ1 pathway by both MCV and murine polyomavirus (MuPyV) MT proteins. The molecular steps in how SFK-PLCγ1 activation is achieved, however, differ between these two viruses.
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Affiliation(s)
- Wen-Yu Peng
- School of Medicine, Tsinghua University, Beijing100084, China
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | - Bizunesh Abere
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Sabrina Toland
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | - Thomas E. Smithgall
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Patrick S. Moore
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Yuan Chang
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA15213
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