Identification and Characterization of a Germline Mutation in CARD11 From a Chinese Case of B Cell Expansion With NF-κB and T Cell Anergy.

Peiwei Zhao,Lei Zhang,Li Tan,Hao Xiong,Qingjie Meng,Xuelian He,Xiankai Zhang,Sukun Luo,Aifen Zhou,Yufeng Huang

doi:10.3389/fimmu.2021.676386

Peiwei Zhao, Lei Zhang + Show 8 more

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https://doi.org/10.3389/fimmu.2021.676386

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Abstract

B cell expansion with NF-κB and T cell anergy (BENTA) is a rare primary immunodeficiency disorder caused by gain-of-function (GOF) mutations in the CARD11 gene. Affected patients present with persistent B cell lymphocytosis in early childhood paired with lymphadenopathy and splenomegaly. Until now only six activating mutations from 14 patients have been reported in CARD11. Here we report a patient from China with polyclonal B cell lymphocytosis and frequent infections in early life. A heterozygous mutation (c.377G>A, G126D) in exon 5 of CARD11 gene (NM_032415) was identified by whole exome sequencing. In vitro functional studies showed that the G126D mutation is associated with increased expression of CARD11 and NF-κB activation in Hela cells. Flow cytometry analysis indicated NK cell activity and CD107a degranulation of the patient were decreased. RNA sequencing analysis showed that a number of genes in NF-κB pathway increased while those involved in NK cell activity and degranulation were down-regulated. In summary, our work identified a de novo germline GOF mutation in CARD11 with functional evidence of BENTA.

Highlights

CARD11 (Caspase recruitment domain 11), a scaffolding protein, is highly expressed in hematopoietic tissue and lymphocytes and required for B-cell receptor (BCR) and T-cell receptor (TCR) signaling to activate Nuclear factor (NF)-kB, c-Jun N-terminal kinase (JNK), and mammalian target of rapamycin pathways [1, 2]
Germline CARD11 mutations have been implicated in several primary immune disorders, including severe combined immunodeficiency (SCID) (OMIM 615206) caused by homozygous loss-of-function (LOF) mutations, B cell expansion with NF-kB and T cell Anergy (BENTA) (OMIM 616452) caused by heterozygous gain-of-function (GOF) mutations [7,8,9], and severe atopic disease (OMIM 617638) caused by heterozygous dominant negative (DN) mutations
As CARD11 serves as a bridge linking cell surface antigen receptor signaling with the activation of the NF-kB, JNK, and mTORC1 signaling, we investigated the contribution of CARD11 mutation to the activation of JNK and mammalian target of rapamycin (mTOR) pathways by assessing their extent of phosphorylation in Hela cells

Summary

Introduction

CARD11 (Caspase recruitment domain 11), a scaffolding protein, is highly expressed in hematopoietic tissue and lymphocytes and required for B-cell receptor (BCR) and T-cell receptor (TCR) signaling to activate Nuclear factor (NF)-kB, c-Jun N-terminal kinase (JNK), and mammalian target of rapamycin (mTOR) pathways [1, 2]. CARD11 is comprised of various defined domains, including N-terminal CARD [1-110], LATCH [112-130], coiled-coil (CC, 130-449), auto-inhibitory (ID, 450-666) domains, and a C-terminal MAGUK domain (667-1140), the last one of which has 3 subdomains: PSD95/ZO-1, SH3, and guanylate kinase. Germline CARD11 mutations have been implicated in several primary immune disorders, including severe combined immunodeficiency (SCID) (OMIM 615206) caused by homozygous loss-of-function (LOF) mutations, B cell expansion with NF-kB and T cell Anergy (BENTA) (OMIM 616452) caused by heterozygous gain-of-function (GOF) mutations [7,8,9], and severe atopic disease (OMIM 617638) caused by heterozygous dominant negative (DN) mutations. All 6 GOF mutations identified are located in the N-terminal CARD, LATCH, and CC domains

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