Deficiency of base excision repair enzyme NEIL3 drives increased predisposition to autoimmunity
Michel J. Massaad, … , Susan S. Wallace, Raif S. Geha
Michel J. Massaad, … , Susan S. Wallace, Raif S. Geha
Published October 17, 2016
Citation Information: J Clin Invest. 2016;126(11):4219-4236. https://doi.org/10.1172/JCI85647.
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Research Article Autoimmunity Immunology

Deficiency of base excision repair enzyme NEIL3 drives increased predisposition to autoimmunity

Abstract

Alterations in the apoptosis of immune cells have been associated with autoimmunity. Here, we have identified a homozygous missense mutation in the gene encoding the base excision repair enzyme Nei endonuclease VIII-like 3 (NEIL3) that abolished enzymatic activity in 3 siblings from a consanguineous family. The NEIL3 mutation was associated with fatal recurrent infections, severe autoimmunity, hypogammaglobulinemia, and impaired B cell function in these individuals. The same homozygous NEIL3 mutation was also identified in an asymptomatic individual who exhibited elevated levels of serum autoantibodies and defective peripheral B cell tolerance, but normal B cell function. Further analysis of the patients revealed an absence of LPS-responsive beige-like anchor (LRBA) protein expression, a known cause of immunodeficiency. We next examined the contribution of NEIL3 to the maintenance of self-tolerance in Neil3–/– mice. Although Neil3–/– mice displayed normal B cell function, they exhibited elevated serum levels of autoantibodies and developed nephritis following treatment with poly(I:C) to mimic microbial stimulation. In Neil3–/– mice, splenic T and B cells as well as germinal center B cells from Peyer’s patches showed marked increases in apoptosis and cell death, indicating the potential release of self-antigens that favor autoimmunity. These findings demonstrate that deficiency in NEIL3 is associated with increased lymphocyte apoptosis, autoantibodies, and predisposition to autoimmunity.

Authors

Michel J. Massaad, Jia Zhou, Daisuke Tsuchimoto, Janet Chou, Haifa Jabara, Erin Janssen, Salomé Glauzy, Brennan G. Olson, Henner Morbach, Toshiro K. Ohsumi, Klaus Schmitz, Markianos Kyriacos, Jennifer Kane, Kumiko Torisu, Yusaku Nakabeppu, Luigi D. Notarangelo, Eliane Chouery, Andre Megarbane, Peter B. Kang, Eman Al-Idrissi, Hasan Aldhekri, Eric Meffre, Masayuki Mizui, George C. Tsokos, John P. Manis, Waleed Al-Herz, Susan S. Wallace, Raif S. Geha

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Figure 3

Family pedigree, NEIL3 mutation, and effect of the mutation on NEIL3 expression and enzymatic activity.

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Family pedigree, NEIL3 mutation, and effect of the mutation on NEIL3 exp...
(A) Family pedigree. (B) Sanger sequencing chromatogram depicting the c.395_396AC>TG homozygous mutation in NEIL3 from patients 2 and 3 and the heterozygous mutation in their parents compared with a control. (C) cDNA organization of NEIL3 and protein structure showing the domains and location of the patients’ mutation indicated by the arrows. Boxes with numbers represent exons. H2TH, helix-2turn-helix; ZF, zinc finger; NLS, nuclear localization signal; TOPIIIα, topoisomerase IIIα. (D) Alignment of the aa sequence surrounding the conserved D132 residue in NEIL3 in homologues from 9 species. (E) Representative immunoblot of NEIL3 in lysates of EBV-transformed B cells from patient 3 and control. WB, Western blot. (F) Representative immunoblot of HA-tagged WT and D132V NEIL3 immunoprecipitated from transfected HeLa cells and detected with anti-HA mAb. (G) Enzymatic activity of HA-tagged WT and D132V NEIL3 immunoprecipitated from transfected HeLa cells and incubated with single-stranded DNA substrates containing the SP [(S)-SP] or the Gh modifications. Empty vector with substrate (vector) or substrate with no enzyme (blank) was used as negative control. Recombinant mouse NEIL3 was used as positive control. Data in E–G are representative of 3 independent experiments.