Background/Purpose: TNF Receptor- Associated Periodic Syndrome (TRAPS) is one of the autoinflammatory diseases characterized by recurrent inflammatory episodes. TRAPS is caused by an autosomal dominant heterozygous mutation in TNFRSF1A gene, which encodes tumor necrosis factor receptor 1 (TNFR1). More than 100 heterozygous TNFRSF1A mutations have been reported. T50M and Cysteine mutations are recognized as TRAPS mutations, the patients with the mutations develop severe TRAPS phenotypes. On the other hand, R92Q and T61I mutations are known as low-penetrant mutations which cause milder TRAPS phenotypes. The molecular pathogenesis by which the mutant TNFR1 causes TRAPS phenotypes is not yet fully understood. Recently we have identified a novel mutation, G58V (p.G87V) in TNFRSF1A, in two individuals in a family with recurrent inflammatory episodes. T61I mutation was also identified in the family. In this study, we examined the effect of the novel G58V mutation on the mutant cells.

Methods: The possible pathogenicity of the G58V mutation was analyzed using the four online prediction tools (SIFT, Polyphen2, PROVEAN and PANTHER). Wild-type (WT) or mutated TNFRSF1A (G58V/T61I, G58V, T61I, T50M, R92Q) constructs were generated by cloning. The TNFR1 constructs were transfected into HEK-293 cells. Expression levels of the TNFR1 were examined by western blotting. To analyze cell surface and intracellular expression of TNFR1, we performed the flow cytometric analysis. NF-κB activation levels at 24 hours after the transfection were measured by the dual-luciferase reporter assay.

Results: The novel G58V mutation was predicted to be a highly damaging amino acid substitution that could affect the function of TNFR1. Expression levels of the WT and mutated TNFR1 proteins are comparable in the whole cell lysates of HEK-293 cells. The cell surface expression of TNFR1 was decreased in the T50M, G58V and G58V/T61I TNFR1-transfected cells compared to WT TNFR1-transfected cells. In contrast, the R92Q and T61I mutation did not affect the expression patter of TNFR1. NF-κB promoter activities in the T50M or the G58V TNFR1-expressing cells were significantly decreased compared to those in WT TNFR1-expressing cells (T50M 21.5 ± 3.6%; G58V 34.8 ± 4.4%; G58V/T61I 56.7 ± 23.9% vs. WT). The R92Q and T61I mutation did not suppress the NF-κB promotor activities.

Conclusion: The T50M mutation suppressed the cell surface expression of TNFR1 and spontaneous NF-κB promoter activity in consistent with a previous report (Blood 2006;108:1320-1327). The newly identified G58V mutation exhibited the similar phenotypes to the pathogenic T50M mutation, suggesting that the G58V is one of the responsible mutations causing TRAPS.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-novel-g58v-mutation-in-the-tnfrsf1a-gene-identified-in-a-family-with-tumor-necrosis-factor-receptor-associated-periodic-syndrome-traps-decreases-the-cell-surface-expression-of-tnfr1/