PT  - JOURNAL ARTICLE
AU  - Huai-Chia Chuang
AU  - Wei-Ting Hung
AU  - Yi-Ming Chen
AU  - Pu-Ming Hsu
AU  - Jeng-Hsien Yen
AU  - Joung-Liang Lan
AU  - Tse-Hua Tan
TI  - Genomic sequencing and functional analyses identify MAP4K3/GLK germline and somatic variants associated with systemic lupus erythematosus
AID  - 10.1136/annrheumdis-2021-221010
DP  - 2022 Feb 01
TA  - Annals of the Rheumatic Diseases
PG  - 243--254
VI  - 81
IP  - 2
4099  - http://ard.bmj.com/content/81/2/243.short
4100  - http://ard.bmj.com/content/81/2/243.full
SO  - Ann Rheum Dis2022 Feb 01; 81
AB  - 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.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.