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The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome.

ABSTRACT: LOXL1 (lysyl oxidase-like 1) has been identified as the major effect locus in pseudoexfoliation (PEX) syndrome, a fibrotic disorder of the extracellular matrix and frequent cause of chronic open-angle glaucoma. However, all known PEX-associated common variants show allele effect reversal in populations of different ancestry, casting doubt on their biological significance. Based on extensive LOXL1 deep sequencing, we report here the identification of a common non-coding sequence variant, rs7173049A>G, located downstream of LOXL1, consistently associated with a decrease in PEX risk (odds ratio, OR?=?0.63; P?=?6.33?×?10-31) in nine different ethnic populations. We provide experimental evidence for a functional enhancer-like regulatory activity of the genomic region surrounding rs7173049 influencing expression levels of ISLR2 (immunoglobulin superfamily containing leucine-rich repeat protein 2) and STRA6 [stimulated by retinoic acid (RA) receptor 6], apparently mediated by allele-specific binding of the transcription factor thyroid hormone receptor beta. We further show that the protective rs7173049-G allele correlates with increased tissue expression levels of ISLR2 and STRA6 and that both genes are significantly downregulated in tissues of PEX patients together with other key components of the STRA6 receptor-driven RA signaling pathway. siRNA-mediated downregulation of RA signaling induces upregulation of LOXL1 and PEX-associated matrix genes in PEX-relevant cell types. These data indicate that dysregulation of STRA6 and impaired retinoid metabolism are involved in the pathophysiology of PEX syndrome and that the variant rs7173049-G, which represents the first common variant at the broad LOXL1 locus without allele effect reversal, mediates a protective effect through upregulation of STRA6 in ocular tissues.

SUBMITTER: Berner D

PROVIDER: S-EPMC6644155 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome.

Berner Daniel D Hoja Ursula U Zenkel Matthias M Ross James Julian JJ Uebe Steffen S Paoli Daniela D Frezzotti Paolo P Rautenbach Robyn M RM Ziskind Ari A Williams Susan E SE Carmichael Trevor R TR Ramsay Michele M Topouzis Fotis F Chatzikyriakidou Anthi A Lambropoulos Alexandros A Sundaresan Periasamy P Ayub Humaira H Akhtar Farah F Qamar Raheel R Zenteno Juan C JC Cruz-Aguilar Marisa M Astakhov Yury S YS Dubina Michael M Wiggs Janey J Ozaki Mineo M Kruse Friedrich E FE Aung Tin T Reis André A Reis André A Khor Chiea Chuen CC Pasutto Francesca F Schlötzer-Schrehardt Ursula U

Human molecular genetics 20190801 15

LOXL1 (lysyl oxidase-like 1) has been identified as the major effect locus in pseudoexfoliation (PEX) syndrome, a fibrotic disorder of the extracellular matrix and frequent cause of chronic open-angle glaucoma. However, all known PEX-associated common variants show allele effect reversal in populations of different ancestry, casting doubt on their biological significance. Based on extensive LOXL1 deep sequencing, we report here the identification of a common non-coding sequence variant, rs717304 ...[more]

PMID: 30986821

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Project description:PurposeTo study lysyl oxidase-like 1 (LOXL1) expression in freshly collected lens capsules from pseudoexfoliation syndrome (XFS), pseudoexfoliation glaucoma (XFG), and normal cataract control individuals. We also investigated the effects of four glaucoma drug medications on LOXL1 expression in primary human lens epithelial cell cultures to see if they could affect LOXL1 expression.MethodsLens capsules were collected at the time of cataract surgery. Controls were matched to age, sex, and ethnicity. Total RNA was isolated from individual lens capsule samples and real-time PCR was performed on each sample using primers flanking the sixth exon of the LOXL1 gene. Cell cultures were grown to confluence in four separate six-well plates at 37 °C in 5% CO2. Each plate was then treated with one of four different glaucoma drugs (brinzolamide 1%, brimonidine tartrate 0.1%, timolol maleate 0.5%, and latanoprost 0.005%) once daily for seven days (at both 1:1,000 and 1:100 concentrations relative to media). Controls were not treated with any drug but media was changed in the same manner. After one week of treatment, cells were harvested and total RNA isolated. Real-time PCR was performed on each group of cells.ResultsSeven XFS, seven XFG, and ten cataract control specimens were analyzed. LOXL1 expression was detected in the lens capsule specimens from each of the four groups. Significant expression differences were found between the control and XFG groups and XFS and XFG groups. No significant difference was observed between the control and XFS group. No significant decrease in LOXL1 expression was seen with drug incubation of the four medications (Brinzolamide, Timolol, Latanoprost, and Brimonidine) at the 1:1,000 drug:media concentrations versus controls. At 10-fold higher concentrations (1:100 drug:media), brinzolamide, timolol maleate, and latanoprost showed small increases in LOXL1 expression relative to controls. This effect was not observed with brimonidine tartrate.ConclusionsThese results establish that LOXL1 expression is reduced in lens capsule specimens from XFG individuals but not XFS. The drug treatment incubation studies suggest that the change in LOXL1 expression observed in XFG is not attributable to glaucoma drug therapy. If a causative functional relationship can be validated, modification of LOXL1 expression in affected tissues may represent a novel treatment strategy for this disorder.

Project description:PURPOSE: Single nucleotide polymorphisms (SNPs) within the lysyl oxidase like-1 gene (LOXL1; rs1048661 and rs3825942) were found to confer risk to pseudoexfoliation glaucoma (XFG) through the pseudoexfoliation syndrome (XFS) in Nordic, Caucasian, and two Asiatic populations (Indian and Japanese). The prevalence (0.2%-0.7%) of XFS in the Chinese is considerably lower compared to Nordic populations. The aim of this study was to determine the association of LOXL1 in Chinese subjects with XFS/XFG. METHODS: Chinese subjects with clinically diagnosed XFS/XFG and normal controls were recruited. Genomic DNA was extracted, and the two LOXL1 SNPs (rs1048661 and rs3825942) were genotyped by bidirectional sequencing. Allele and genotype frequencies were compared between cases and unrelated controls using PLINK. Linkage disequilibrium (LD) calculations and haplotype association analysis were done using the Haploview package and WHAP package, respectively. RESULTS: Sixty-two Chinese patients (17 XFG and 45 XFS) and 171 Chinese controls were studied. The G allele of LOXL1 SNP rs3825942 was moderately associated (OR=10.97, p=0.0018) with pseudoxfoliation in the Chinese. The frequency of the G allele of rs1048661 was not significantly different in cases compared to controls (p=0.142) in the allelic association test. However, the genotype test showed marginal association for rs1048661 (p=0.030). Only three haplotypes were observed (T-G, G-G, and G-A) with G-G as a risk haplotype (p=0.0034) and G-A as a protective haplotype (p=0.00039). T-G, which was a risk haplotype in the Japanese, was not associated with XFG in the Chinese (p=0.124). CONCLUSIONS: Polymorphisms in LOXL1 confer risk to XFS/XFG in the Chinese. The lower incidence of XFS compared to other populations suggests additional genetic or environmental factors to have a major influence on the phenotypic expression of XFS in the Chinese. The G allele of rs3825942 has been shown to be associated with XFS/XFG in all populations studied to date.

Project description:This study presents two new concepts and definitions to the medical literature. One of those is "endogenous retinoic acid theory" and the other "retinoic acid depletion syndrome". A new classification will be provided for the immune system: "retinoic acid-dependent component" and "retinoic acid non-dependent component". If this theory is verified, all the diseases where the retinoic acid metabolism is defective and retinoic acid levels are low will be identified and new approaches will be developed fortreating such diseases. When the need for retinoic acids increases, such as acute infection, high fever, severe catabolic process, or chronic antigenic stimulation, cytochrome oxidase enzymes are inhibited by drugs or internal mechanisms. Metabolism and excretion of retinoic acids stored in the liver are prevented. In this way, retinoic acid levels in the blood are raised to therapeutic levels. This is called "Endogenous Retinoic Acid Theory". Retinoic acids also manage their metabolism through feedback mechanisms. Despite compensatory mechanisms, causes such as high fever, serious catabolic process and excessively large viral genome (SARS-CoV-2), excessive use of RIG-I and Type I interferon synthesis pathway using retinoic acid causes emptying of retinoic acid stores. As a result, the RIG-I pathway becomes ineffective, Type I IFN synthesis stops, and the congenital immune system collapses. Then the immune mechanism passes to TLR3, TLR7, TLR8, TLR9, MDA5 and UPS pathways in the monocyte, macrophage, neutrophil and dendritic cells of the adaptive immune defense system that do not require retinoic acid. This leads to excessive TNFα and cytokine discharge from the pathway. With the depletion of retinoic acid stores as a result of this overuse, the immune defense mechanism switches from the congenital immune system to the adaptive immune system, where retinoic acids cannot be used. As a result of this depletion of retinoic acids, the shift of the immune system to the NFκB arm, which causes excessive cytokine release, is called "retinoic acid depletion syndrome". COVID-19 and previously defined sepsis, SIRS and ARDS are each retinoic acid depletion syndrome. We claim that retinoic acid metabolism is defective in most inflammatory diseases, particularly COVID-19 (cytokine storm) sepsis, SIRS and ARDS. Finding a solution to this mechanism will bring a new perspective and treatment approach to such diseases.

Dataset Information

The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome.

Publications

The protective variant rs7173049 at LOXL1 locus impacts on retinoic acid signaling pathway in pseudoexfoliation syndrome.

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