Article Text

Genomic sequencing and functional analyses identify MAP4K3/GLK germline and somatic variants associated with systemic lupus erythematosus
  1. Huai-Chia Chuang1,
  2. Wei-Ting Hung2,
  3. Yi-Ming Chen2,
  4. Pu-Ming Hsu1,
  5. Jeng-Hsien Yen3,
  6. Joung-Liang Lan2,4,5,
  7. Tse-Hua Tan1,6
  1. 1 Immunology Research Center, National Health Research Institutes, Zhunan, Taiwan
  2. 2 Division of Allergy, Immunology and Rheumatology, Taichung Veterans General Hospital, Taichung, Taiwan
  3. 3 Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan
  4. 4 Rheumatology and Immunology Center, China Medical University Hospital, Taichung, Taiwan
  5. 5 College of Medicine, China Medical University, Taichung, Taiwan
  6. 6 Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, USA
  1. Correspondence to Professor Tse-Hua Tan, Immunology Research Center, National Health Research Institutes, Zhunan, Miaoli Count 350, Taiwan; ttan{at}nhri.edu.tw; Dr Joung-Liang Lan; d8838{at}mail.cmuh.org.tw; Dr Jeng-Hsien Yen; jehsye{at}kmu.edu.tw; Dr Huai-Chia Chuang; cinth{at}nhri.org.tw

Abstract

Objectives MAP4K3 (GLK) overexpression in T cells induces interleukin (IL)-17A production and autoimmune responses. GLK overexpressing T-cell population is correlated with severity of human systemic lupus erythematosus (SLE); however, it is unclear how GLK is upregulated in patients with SLE.

Methods We enrolled 181 patients with SLE and 250 individuals without SLE (93 healthy controls and 157 family members of patients with SLE) in two independent cohorts from different hospitals/cities. Genomic DNAs of peripheral blood mononuclear cells were subjected to next-generation sequencing to identify GLK gene variants. The functional consequences of the identified GLK germline or somatic variants were investigated using site-directed mutagenesis and cell transfection, followed by reporter assays, mass spectrometry, immunoblotting, coimmunoprecipitation, and in situ proximity ligation assays.

Results We identified 58 patients with SLE from Cohort #1 and #2 with higher frequencies of a somatic variant (chr2:39 477 124 A>G) in GLK 3′-untranslated region (UTR); these patients with SLE showed increased serum anti-double-stranded DNA levels and decreased serum C3/C4 levels. This somatic variant in 3′-UTR enhanced GLK mRNA levels in T cells. In addition, we identified five patients with SLE with GLK (A410T) germline variant in Cohort #1 and #2, as well as two other patients with SLE with GLK (K650R) germline variant in Cohort #1. Another GLK germline variant, A579T, was also detected in one patient with SLE from Cohort #2. Both GLK (A410T) and GLK (K650R) mutants inhibited GLK ubiquitination induced by the novel E3 ligase makorin ring-finger protein 4 (MKRN4), leading to GLK protein stabilisation.

Conclusions Multiple GLK germline and somatic variants cause GLK induction by increasing mRNA or protein stability in patients with SLE.

  • lupus erythematosus
  • systemic
  • autoimmune diseases
  • inflammation

Data availability statement

Data are available upon reasonable request. The data supporting the findings of this study are documented within the paper and are available from the corresponding author upon request.

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Data availability statement

Data are available upon reasonable request. The data supporting the findings of this study are documented within the paper and are available from the corresponding author upon request.

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Footnotes

  • Handling editor Josef S Smolen

  • H-CC and W-TH contributed equally.

  • Contributors H-CC performed experiments, literature search, data analysis, data interpretation, study design, statistical analyses and manuscript writing. W-TH collected family data, provided patient samples, analysed clinical data and performed statistical analyses. Y-MC collected family data and provided patient samples. P-MH performed biochemistry experiments. J-HY provided patient samples and analysed clinical data. J-LL conceived the study, provided patient samples and analysed clinical data. T-HT conceived the study, supervised experiments, interpreted data and wrote the manuscript.

  • Funding This work was supported by grants from the National Health Research Institutes, Taiwan (IM-107-PP-01 and IM-107-SP-01 to T-HT) and Ministry of Science and Technology, Taiwan (MOST-106-2321-B-400-013 to T-HT). T-HT is a Taiwan Bio-Development Foundation (TBF) Chair in Biotechnology.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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