Disease-associated AIOLOS variants lead to immune deficiency/dysregulation by haploinsufficiency and redefine AIOLOS functional domains
Hye Sun Kuehn, … , Svetlana O. Sharapova, Sergio D. Rosenzweig
Hye Sun Kuehn, … , Svetlana O. Sharapova, Sergio D. Rosenzweig
Published November 28, 2023
Citation Information: J Clin Invest. 2024;134(3):e172573. https://doi.org/10.1172/JCI172573.
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Disease-associated AIOLOS variants lead to immune deficiency/dysregulation by haploinsufficiency and redefine AIOLOS functional domains

Abstract

AIOLOS, also known as IKZF3, is a transcription factor that is highly expressed in the lymphoid lineage and is critical for lymphocyte differentiation and development. Here, we report on 9 individuals from 3 unrelated families carrying AIOLOS variants Q402* or E82K, which led to AIOLOS haploinsufficiency through different mechanisms of action. Nonsense mutant Q402* displayed abnormal DNA binding, pericentromeric targeting, posttranscriptional modification, and transcriptome regulation. Structurally, the mutant lacked the AIOLOS zinc finger (ZF) 5–6 dimerization domain, but was still able to homodimerize with WT AIOLOS and negatively regulate DNA binding through ZF1, a previously unrecognized function for this domain. Missense mutant E82K showed overall normal AIOLOS functions; however, by affecting a redefined AIOLOS protein stability domain, it also led to haploinsufficiency. Patients with AIOLOS haploinsufficiency showed hypogammaglobulinemia, recurrent infections, autoimmunity, and allergy, but with incomplete clinical penetrance. Altogether, these data redefine the AIOLOS structure–function relationship and expand the spectrum of AIOLOS-associated diseases.

Authors

Hye Sun Kuehn, Inga S. Sakovich, Julie E. Niemela, Agustin A. Gil Silva, Jennifer L. Stoddard, Ekaterina A. Polyakova, Ana Esteve Sole, Svetlana N. Aleshkevich, Tatjana A. Uglova, Mikhail V. Belevtsev, Vladislav R. Vertelko, Tatsiana V. Shman, Aleksandra N. Kupchinskaya, Jolan E. Walter, Thomas A. Fleisher, Luigi D. Notarangelo, Xiao P. Peng, Ottavia M. Delmonte, Svetlana O. Sharapova, Sergio D. Rosenzweig

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Figure 6

The impact of AIOLOS mutants on protein stability and posttranslational modification.

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The impact of AIOLOS mutants on protein stability and posttranslational ...
(A) HEK293T cells were transfected with indicated vectors. The following day, cells were treated with cycloheximide (CHX, 10 μg/mL) in the presence and absence of epoxomicin (100 nM) or bortezomib (50 nM) for 8 hours. Representative images from 3 to 4 independent experiments are shown. The AIOLOS expression was normalized by the loading control, and the relative AIOLOS protein stability was calculated by dividing the CHX-treated sample by the untreated sample (× 100) for each group. Data indicate mean ± SEM. (B) HEK293T cells were cotransfected with HA-AIOLOS and Flag-Ubiquitin. After 48 hours of incubation, cells were treated with Epoxomicin (100 nM) for 3 hours. The protein lysates were prepared and immunoprecipitated under nondenaturing conditions with an anti-rabbit HA antibody. Immunoblot was performed using an anti-ubiquitin antibody or an anti-HA antibody. (C and D) HEK293T cells were transfected with HA or Flag-tagged AIOLOS WT or the indicated mutant together with GFP-SUMO1/2 or with HA-HDAC1. 24–48 hours after transfection, protein lysates were prepared and subjected to immunoprecipitations. Western blot data of the IP samples with indicated antibodies are shown. Representative images from 3 independent experiments are shown. The arrow indicates the heavy chain of the anti-HA antibody (B–D).