title: SAG/Rbx2-Dependent Neddylation Regulates T-Cell Responses.
abstract: Neddylation is a crucial post-translational modification that depends on the E3 cullin ring ligase (CRL). The E2-adapter component of the CRL, sensitive to apoptosis gene (SAG), is critical for the function of CRL-mediated ubiquitination; thus, the deletion of SAG regulates neddylation. We examined the role of SAG-dependent neddylation in T-cell-mediated immunity using multiple approaches: a novel T-cell-specific, SAG genetic knockout (KO) and chemical inhibition with small-molecule MLN4924. The KO animals were viable and showed phenotypically normal mature T-cell development. However, in vitro stimulation of KO T cells revealed significantly decreased activation, proliferation, and T-effector cytokine release, compared with WT. Using in vivo clinically relevant models of allogeneic bone marrow transplantation also demonstrated reduced proliferation and effector cytokine secretion associated with markedly reduced graft-versus-host disease. Similar in vitro and in vivo results were observed with the small-molecule inhibitor of neddylation, MLN4924. Mechanistic studies demonstrated that SAG-mediated effects in T cells were concomitant with an increase in suppressor of cytokine signaling, but not NF-κB translocation. Our studies suggest that SAG is a novel molecular target that regulates T-cell responses and that inhibiting neddylation with the clinically available small-molecule MLN4924 may represent a novel strategy to mitigate T-cell-mediated immunopathologies, such as graft-versus-host disease.
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan; Graduate Program in Immunology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Mathewson
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan; Graduate Program in Immunology, University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Shin-Rong
authors.initials: SR
authors.lastname: Wu
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Toubai
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Katherine
authors.initials: K
authors.lastname: Oravecz-Wilson
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Corinne
authors.initials: C
authors.lastname: Rossi
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Zajac
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan. Electronic address: reddypr@med.umich.edu.
authors.forename: Pavan
authors.initials: P
authors.lastname: Reddy
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D005260:Female; D020869:Gene Expression Profiling; D006086:Graft vs Host Disease / Q000276:immunology* / Q000628:therapy; D006801:Humans; D007111:Immunity, Cellular; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D011499:Protein Processing, Post-Translational; D011743:Pyrimidines / Q000494:pharmacology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D002352:Carrier Proteins; D003517:Cyclopentanes; D011743:Pyrimidines; C573100:SAG protein, mouse; D044767:Ubiquitin-Protein Ligases; C539933:pevonedistat