Attenuation of HOIL-1L ligase activity promotes systemic autoimmune disorders by augmenting linear ubiquitin signaling
Yasuhiro Fuseya, Keiichiro Kadoba, Xiaoxi Liu, Hiroyuki Suetsugu, Takeshi Iwasaki, Koichiro Ohmura, Takayuki Sumida, Yuta Kochi, Akio Morinobu, Chikashi Terao, Kazuhiro Iwai
Yasuhiro Fuseya, Keiichiro Kadoba, Xiaoxi Liu, Hiroyuki Suetsugu, Takeshi Iwasaki, Koichiro Ohmura, Takayuki Sumida, Yuta Kochi, Akio Morinobu, Chikashi Terao, Kazuhiro Iwai
View: Text | PDF
Research Article Cell biology

Attenuation of HOIL-1L ligase activity promotes systemic autoimmune disorders by augmenting linear ubiquitin signaling

Abstract

Linear ubiquitin chains, which are generated specifically by the linear ubiquitin assembly complex (LUBAC) ubiquitin ligase, play crucial roles in immune signaling, including NF-κB activation. LUBAC comprises catalytic large isoform of heme-oxidized iron regulatory protein 2 ubiquitin ligase 1 (HOIL-1L) interacting protein (HOIP), accessory HOIL-1L, and SHANK-associated RH domain-interacting protein (SHARPIN). Deletion of the ubiquitin ligase activity of HOIL-1L, an accessory ligase of LUBAC, augments LUBAC functions by enhancing LUBAC-mediated linear ubiquitination, which is catalyzed by HOIP. Here, we show that HOIL-1L ΔRING1 mice, which exhibit augmented LUBAC functions upon loss of the HOIL-1L ligase, developed systemic lupus erythematosus (SLE) and Sjögren’s syndrome in a female-dominant fashion. Augmented LUBAC activity led to hyperactivation of both lymphoid and myeloid cells. In line with the findings in mice, we sought to identify missense single nucleotide polymorphisms/variations of the RBCK1/HOIL-1L gene in humans that attenuate HOIL-1L ligase activity. We found that the R464H variant, which is encoded by rs774507518 within the RBCK1/HOIL-1L gene, attenuated HOIL-1L ligase activity and augmented LUBAC-mediated immune signaling, including that mediated by Toll-like receptors. We also found that rs774507518 was enriched significantly in patients with SLE, strongly suggesting that RBCK1/HOIL-1L is an SLE susceptibility gene and that augmented linear ubiquitin signaling generated specifically by LUBAC underlies the pathogenesis of this prototype systemic autoimmune disease.

Authors

Yasuhiro Fuseya, Keiichiro Kadoba, Xiaoxi Liu, Hiroyuki Suetsugu, Takeshi Iwasaki, Koichiro Ohmura, Takayuki Sumida, Yuta Kochi, Akio Morinobu, Chikashi Terao, Kazuhiro Iwai

×

Figure 5

Augmented TLR signaling in HOIL-1L ΔRING1 mice.

Options: View larger image (or click on image) Download as PowerPoint
Augmented TLR signaling in HOIL-1L ΔRING1 mice. (A and D) Splenic primar...
(A and D) Splenic primary B cells from 12-week-old littermate female mice of the indicated genotype were treated with LPS (20 mg/mL) (A) or R848 (1 mg/mL) (D) for the indicated times, then assessed by immunoblotting with the indicated antibodies. (B and C) QPCR analysis of splenic primary B cells from 10- to 12-week-old female mice of the indicated genotype. Splenic B lymphocytes were treated with or without LPS (20 mg/mL) for the indicated times, followed by qPCR (C). n = 4 per genotype. For each target, data sets of B and C (0 hours) are the same. (E and F) QPCR analysis of splenic T cells from 10- to 12-week-old female mice of the indicated genotype. Splenic primary T cells were treated with CD3 (1 mg/mL) and CD28 (1 mg/mL) for the indicated times, followed by qPCR (F). n = 4 per genotype. For each target, data sets of F (0 hours) and E are the same. (G and H) BMDMs from 12-week-old littermate female mice of the indicated genotype were treated with LPS (10 mg/mL) (G) or R848 (1 mg/mL) (H) for the indicated times and assessed by immunoblotting with the indicated antibodies. (I and J) QPCR analysis from BMDMs from 10- to 12-week-old female mice of the indicated genotype. BMDMs were treated with LPS (10 ng /mL) for the indicated times, followed by qPCR (I). n = 4 per genotype. For each target, data sets of I (0 hours) and J are the same. (B, C, E, F, I, and J) Data are expressed as the mean ± SD. P values were calculated by 1-way ANOVA, followed by Dunnett’s multiple comparisons test.