Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose:
We established an X-linked TLR7 3’UTR SNP (rs3853839) as a risk locus for SLE in 9,274 Eastern Asians (Pcombined = 6.5×10-10). Risk-allele carriers have increased TLR7 transcripts and more pronounced IFN signature than non risk-allele carriers. The current study sought replication of SLE-associated SNP(s) in non-Asian ancestries and explored the molecular mechanism underlying the identified genetic variant that affects TLR7 expression.
Methods:
We conducted genotyping and imputation for 67-115 SNPs (varying among different ancestral backgrounds) covering ~80kb of TLR7-TLR8 region in European Americans (EA), African Americans (AA) and Hispanics enriched for the Amerindian-European admixture (HS). Each SNP was assessed for the association with SLE. Haplotype-based conditional testing was conducted to distinguish independent signals from associated SNPs and Mantel-Haenszel testing was used in the trans-ancestral meta-analysis. Association of genotype and TLR7 expression was examined using the RT-PCR, flow cytometry and reporter assays. Pyrosequencing was used to measure allelic variations in TLR7 transcript level.
Results:
Our trans-ancestral fine-mapping confirmed the TLR7 3’UTR SNP rs3853839 as the only variant in TLR7-TLR8 region exhibiting consistent and independent association with SLE (P meta = 1.7×10-10, OR [95%CI] =1.24 [1.18-1.34]) in 13,339 subjects of EA (3,936 cases vs. 3,491 controls), AA (1,679 vs. 1,934) and HS (1,492 vs. 807) ancestries. The risk G allele conferred elevated TLR7 expression in PBMCs from healthy individuals at both mRNA (P = 0.01 in men and 0.02 in women) and protein level (P = 0.009 in men and 0.038 in women). PBMCs from heterozygous women exhibited higher G/C allele ratios in TLR7 transcripts 4 hours after incubation with actinomycin D (inhibitor of transcription initiation) than with vehicle control (P = 0.04), indicating a slower degradation of the G allele-containing transcripts. The non-risk allele, but not risk-allele, was predicted to match microRNA-3148 (miR-3148) at the second base in the binding site. Transcript levels of miR-3148 and TLR7 in PBMCs from 16 SLE patients and 21 normal controls were inversely correlated (R2 = 0.255, P = 0.001), suggesting modulation of TLR7 expression by miR-3148. Overexpression of miR-3148 via transient transfection into HEK 293 cells led to more than 2-fold reduction in luciferase activity driven by the TLR7 3’UTR segment containing the non-risk allele compared to that containing the risk allele (P = 0.002).
Conclusion:
We identified and confirmed a genome-wide significant association between the TLR7 3’UTR SNP and SLE susceptibility in 22,613 subjects of Eastern Asian, European American, African American and Hispanic ancestries (P meta = 6.4×10-19, OR [95%CI] =1.26 [1.20-1.32]). Reduced modulation by miRNA-3148 conferred a slower degradation of the risk allele containing TLR7 transcripts, resulting in elevated levels of gene products and more robust type I IFN signature.
Disclosure:
Y. Deng,
None;
J. Zhao,
None;
D. Sakurai,
None;
K. M. Kaufman,
None;
J. C. Edberg,
None;
R. P. Kimberly,
None;
D. L. Kamen,
None;
G. S. Gilkeson,
None;
C. O. Jacob,
None;
R. H. Scofield,
None;
C. D. Langefeld,
None;
J. A. Kelly,
None;
M. E. Alarcün-Riquelme on behalf of BIOLUPUS and GENLES networks,
None;
J. B. Harley,
None;
T. J. Vyse,
None;
B. I. Freedman,
None;
P. M. Gaffney,
None;
K. Moser Sivils,
None;
J. A. James,
None;
T. B. Niewold,
None;
R. M. Cantor,
None;
W. Chen,
None;
B. H. Hahn,
None;
E. E. Brown on behalf of PROFILE,
None;
B. P. Tsao,
None.
ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-sle-associated-tlr7-variant-confers-differential-gene-expression-modulated-by-microrna-3148/