High Temperature Requirement A1 Research Articles

Age-Related Macular Degeneration-Associated Silent Polymorphisms in HtrA1 Impair Its Ability To Antagonize Insulin-Like Growth Factor 1

Synonymous single nucleotide polymorphisms (SNPs) within a transcript's coding region produce no change in the amino acid sequence of the protein product and are therefore intuitively assumed to have a neutral effect on protein function. We report that two common variants of high-temperature requirement A1 (HTRA1) that increase the inherited risk of neovascular age-related macular degeneration (NvAMD) harbor synonymous SNPs within exon 1 of HTRA1 that convert common codons for Ala34 and Gly36 to less frequently used codons. The frequent-to-rare codon conversion reduced the mRNA translation rate and appeared to compromise HtrA1's conformation and function. The protein product generated from the SNP-containing cDNA displayed enhanced susceptibility to proteolysis and a reduced affinity for an anti-HtrA1 antibody. The NvAMD-associated synonymous polymorphisms lie within HtrA1's putative insulin-like growth factor 1 (IGF-1) binding domain. They reduced HtrA1's abilities to associate with IGF-1 and to ameliorate IGF-1-stimulated signaling events and cellular responses. These observations highlight the relevance of synonymous codon usage to protein function and implicate homeostatic protein quality control mechanisms that may go awry in NvAMD.

High temperature requirement A1 in placental tissues and serum from pre-eclamptic pregnancies with or without fetal growth restriction

IntroductionPre-eclampsia (PE) is the most serious syndrome of human pregnancy and it is potentially life-threatening for both mother and fetus. The aim of the study was to identify the role of high temperature requirement A1 (HtrA1) in pre-eclampsia.Material and methodsOne hundred consecutive pregnancies complicated by PE and 100 normal controls were included in our study. The changes in serum HtrA1 and fetal growth restriction were recorded. The placentae after delivery was also obtained for laboratory analyses.ResultsHigh temperature requirement A1 expressed positively in all placenta tissues, but showed higher expression from control, PE with AGA (pre-eclamptic pregnancies with appropriate-for-gestational-age newborns) to PE with fetal growth restriction (FGR) groups. Early-onset PE happened more frequently while in PE with AGA, late-onset PE was more common. Additionally, we found that only during ∼28-32 gestational weeks, sera HtrA1 level of PE with AGA and PE with FGR was increased significantly compared with the control group (p < 0.05). In contrast, there was no significant difference between groups in other gestational ages in the third trimester (p > 0.05).ConclusionsHtrA1 could potentially affect trophoblast migration and invasion during placentation, resulting in the shallow invasion noted in pre-eclampsia. HtrA1 may play an important role in the etiology and severity of PE and FGR. But the actual mechanism still needs deep research.

HtrA1 Is a Novel Antagonist Controlling Fibroblast Growth Factor (FGF) Signaling via Cleavage of FGF8

Accumulating evidence suggests that HtrA1 (high-temperature requirement A1) is involved in modulating crucial cellular processes and implicated in life-threatening diseases, such as cancer and neuropathological disorders; however, the exact functions of this protease in vivo remain unknown. Here, we show that loss of HtrA1 function increases fibroblast growth factor 8 (FGF8) mRNA levels and triggers activation of FGF signaling, resulting in dorsalization in zebrafish embryos. Notably, HtrA1 directly cleaves FGF8 in the extracellular region, and this cleavage results in decreased activation of FGF signaling, which is essential for many physiological processes. Therefore, HtrA1 is indispensable for dorsoventral patterning in early zebrafish embryogenesis and serves as a key upstream regulator of FGF signaling through the control of FGF levels. Furthermore, this study offers insight into new strategies to control human diseases associated with HtrA1 and FGF signaling.

Changes in the Level of Serum High-Temperature Requirement A1 (HtrA1) during Pregnancy and Its Relationship to Preeclampsia

Objective. To investigate the expression and changes of high-temperature requirement A1 (HtrA1) during pregnancy and the use of this value in predicting preeclampsia. Method. Serum samples were collected from pregnant mothers at different gestational weeks, and double-antibody sandwich enzyme-linked immunosorbent assay was employed to describe the changes in HtrA1 in serum during pregnancy. Results. (i) In Xi’an area of China, the incidence of preeclampsia was 4.95%, including 0.85% of early-onset type and 4.10% of late-onset type; (ii) the HtrA1 showed a lognormal distribution during pregnancy in the maternal serum, with the peak at 17–20 weeks of pregnancy; (iii) the HtrA1 levels in preeclampsia mothers peaked at 13–16 weeks of pregnancy, followed by acute decline until 21–24 weeks, then remained stable; (iv) the HtrA1 levels in preeclampsia mothers were higher than the control group in 13–16 weeks and lower than that in 21–24 weeks (p < 0.05); (v) the criteria using lgHtrA1 level at 1.684 during 13–16 weeks of pregnancy could predict hypertension disorders complicating pregnancy (HDCP) with sensitivity of 62.1% and specificity of 53.7%. This could be improved to 85 and 83%, respectively, when combined with body mass index as well as education background of the mother. Conclusion. (i) HtrA1 showed lognormal distribution during pregnancy for all populations; (ii) HtrA1 level peaked at 17–20 weeks in normal group of pregnant mothers, and the increase of HtrA1 level in 13–16 weeks could predict the risk of preeclampsia; (iii) the risk calculation formula for preeclampsia: p (%) = eY/(1 + eY) (Y = −15.87 + 3.706 × lgHtrA1 + 0.134 × mean arterial pressure (MAP) − 1.4 × education level code); e = 2.718.

Induction of high temperature requirement A1, a serine protease, by TGF-beta1 in knee joints of mouse models of OA

Induction of high temperature requirement A1, a serine protease, by TGF-beta1 in knee joints of mouse models of OA

Composition and proteolytic processing of corneal deposits associated with mutations in the TGFBI gene

Different types of granular corneal dystrophy (GCD) and lattice corneal dystrophy (LCD) are associated with mutations in the transforming growth factor beta induced gene (TGFBI). These dystrophies are characterized by the formation of non-amyloid granular deposits (GCDs) and amyloid (LCD type 1 and its variants) in the cornea. Typical corneal non-amyloid deposits from GCD type 2 (R124H), amyloid from a variant of LCD type 1 (V624M) and disease-free tissue controls were procured by laser capture microdissection and analyzed by tandem mass spectrometry. Label-free quantitative comparisons of deposits and controls suggested that the non-amyloid sample (R124H) specifically accumulated transforming growth factor beta induced protein (TGFBIp/keratoepithelin/βig-h3), serum amyloid P-component, clusterin, type III collagen, keratin 3, and histone H3-like protein. The amyloid (V624M) similarly accumulated serum amyloid P-component and clusterin but also a C-terminal fragment of TGFBIp containing residues Y571–R588 derived from the fourth fasciclin-1 domain (FAS1-4), apolipoprotein E and apolipoprotein A-IV. Significantly, analyses of the amyloid sample also revealed the presence of the serine protease Htr (High-temperature requirement) A1 and a number of proteolytic cleavage sites in the FAS1-4 domain of TGFBIp. These cleavage sites were consistent with the ligand binding and proteolytic activity of HtrA1 suggesting that it plays a role in the proteolytic processing of the amyloidogenic FAS1-4 domain. Taken together, the data suggest that the amyloidogenic-prone region of the fourth FAS1 domain of TGFBIp encompasses the Y571–R588 peptide and that HtrA1 is involved in the proteolytic processing of TGFBIp-derived amyloid in vivo.

Overexpression of HTRA1 Leads to Ultrastructural Changes in the Elastic Layer of Bruch's Membrane via Cleavage of Extracellular Matrix Components

Variants in the chromosomal region 10q26 are strongly associated with an increased risk for age-related macular degeneration (AMD). Two potential AMD genes are located in this region: ARMS2 and HTRA1 (high-temperature requirement A1). Previous studies have suggested that polymorphisms in the promotor region of HTRA1 result in overexpression of HTRA1 protein. This study investigated the role of HTRA1 overexpression in the pathogenesis of AMD. Transgenic Htra1 mice overexpressing the murine protein in the retinal pigment epithelium (RPE) layer of the retina were generated and characterized by transmission electron microscopy, immunofluorescence staining and Western Blot analysis. The elastic layer of Bruch's membrane (BM) in the Htra1 transgenic mice was fragmented and less continuous than in wild type (WT) controls. Recombinant HTRA1 lacking the N-terminal domain cleaved various extracellular matrix (ECM) proteins. Subsequent Western Blot analysis revealed an overexpression of fibronectin fragments and a reduction of fibulin 5 and tropoelastin in the RPE/choroid layer in transgenic mice compared to WT. Fibulin 5 is essential for elastogenesis by promoting elastic fiber assembly and maturation. Taken together, our data implicate that HTRA1 overexpression leads to an altered elastogenesis in BM through fibulin 5 cleavage. It highlights the importance of ECM related proteins in the development of AMD and links HTRA1 to other AMD risk genes such as fibulin 5, fibulin 6, ARMS2 and TIMP3.

Age-Related Macular Degeneration and Association ofCFHY402H andLOC387715A69S Polymorphisms in a Turkish Population

Age-related macular degeneration (AMD) is a disease with multifactorial etiology characterized by irreversible loss of central visual acuity. The discovery of susceptive single-nucleotide polymorphisms (SNPs) has progressed our understanding of AMD. Complement factor H (CFH) gene Y402H polymorphism and high-temperature requirement A-1 (HTRA1) LOC387715 gene A69S polymorphisms are the most important SNPs reported in the literature. Determination of genetic risk factors and genotype-phenotype relationship in AMD may result in rapid and cost-effective therapeutic applications for young and old population. In this study, we hypothesized a potential association between CFH gene Y402H and HTRA1 LOC387715 gene A69S polymorphism in Turkish AMD patients. In blood samples from a total of 252 individuals, 147 clinically diagnosed as AMD and the others control, polymorphic sites in CFH, Y402H (Tsp509I T/C), and HTRA1, LOC387715 A69S (FnuHI G/T), were determined by polymerase chain reaction-restriction fragment length polymorphism analysis. There was significant difference between CFH genotypes in the AMD group, TT 21.8%, TC 48.3%, and CC 29.9%, and in the control subjects, TT 45% (p=0.003), TC 41% (p=0.0001), and CC 14% (p=0.0001). Further, the A69S polymorphism of LOC387715 was investigated and found to be significantly associated with AMD. LOC387715 genotypes in the AMD group were GG 30.6%, GT 38.1%, and TT 31.3% and in the control subjects were GG 59% (p=0.027), GT 39% (p=0.0001), and TT 2% (p=0.0001), respectively. We also found that Y402H C and A69S T allele were associated with AMD. This is the first study showing that Y402H and LOC387715 are associated with AMD in Turkish population.

TGF-β family signaling contributes to human cerebral small vessel disease

The discovery of the causative gene for hereditary cerebral small vessel disease (CARASIL: Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) opens a new avenue for exploring the pathogenesis of cerebral small vessel disease. The causative gene for CARASIL is HTRA1 (high-temperature requirement A1). HTRA1 is a serine protease and inhibits TGF-β signaling in their protease activity-dependent manner. The CARASIL-associated mutant HTRA1s lost their protease activity and increase the TGF-β family signaling. However the precious molecular mechanism for inhibition of TGF-β signaling by HTRA1 has not been elucidated. We have found that HTRA1 aberrantly cleaved pro-TGF-β in an endoplasmic reticulum and the cleaved products were degraded by the endoplasmic reticulum-associated degradation pathway. The result reconfirms the importance of HTRA1 for TGF-β signaling. The study for Marfan syndrome, which is caused by the increasing TGF-β signaling in aortic artery, indicates that the angiotensin I receptor antagonist, a drug already in clinical use for hypertension, inhibits TGF-β signaling and ameliorates the disease progression in model mouse as well as patients with Marfan syndrome. In human brain, angiotensin I receptor antagonist also inhibits TGF-β signaling. Therefore angiotensin I receptor antagonist warrants investigation as a therapeutic strategy for patients with CARASIL.

Complement Factor H and High-Temperature Requirement A-1 Genotypes and Treatment Response of Age-related Macular Degeneration

To determine whether there is an association between complement factor H (CFH), high-temperature requirement A-1 (HTRA1), vascular endothelial growth factor (VEGF), and pigment epithelium-derived factor (PEDF) genotypes and response to treatment with photodynamic therapy (PDT) for age-related macular degeneration (AMD) in a Japanese population. Prospective, case-control study. One hundred ten patients with exudative AMD treated by verteporfin PDT were recruited prospectively at the Department of Ophthalmology, Saitama Medical University Hospital, Saitama, Japan. The patients were genotyped for 4 single nucleotide polymorphisms (SNPs; rs800292, rs1061170, rs1410996, rs2274700) in the CFH gene, a rs11200638-SNP in the HTRA1 gene, 3 SNPs (rs699947, rs1570360, rs2010963) in the VEGF gene, and 4 SNPs (rs12150053, rs12948385, rs9913583, rs1136287) in the PEDF gene using a TaqMan assay. The treatment outcomes and genotypes of CFH, HTRA1, VEGF, and PEDF polymorphisms. Best-corrected visual acuity 1 year after PDT was significantly increased in patients with the HTRA1-rs11200638 GG genotype as compared with patients with the GA or AA genotypes (P = 2.9 × 10⁻², 7.0 × 10⁻⁴, respectively). The rate of recurrence in the 12-month period after PDT was also associated with HTRA1-rs11200638 genotype (P = 3.12 × 10⁻²). Patients with the AA genotype of HTRA1-rs11200638 had an approximately 6-fold greater risk of the recurrence than patients with the GG genotype (P = 5.58 × 10⁻³). Significant differences were demonstrated in the mean time interval from the initial treatment to the time of recurrence for the genotypes of CFH-rs1410996/-rs2274700 (P = 8.50 × 10⁻³). The HTRA1-rs11200638 and CFH-rs1410996/-rs2274700 variants were associated with response to PDT in this study population. These variants may be used for genetic biomarkers to estimate visual outcomes and recurrences in the response to PDT with significant predictive power.

Association study on single nucleotide polymorphisms in HTRA1 gene and rheumatoid arthritis

To study the association between the single nucleotide polymorphisms (SNPs) in the high-temperature requirement A-1 (HTRA1) gene and rheumatoid arthritis (RA) in Chinese Han population. Five SNPs in the HTRA1 gene (rs2014307, rs2248799, rs2300433, rs714816 and rs2268356) were genotyped by ABI Snapshot method in Han Chinese cohort composed of 344 patients with RA and 288 healthy controls. The serum rheumatoid factor (RF) and C-reactive protein (CRP) of the patients were determined by endpoint nephelometry method. Genotypes of all the five SNPs in the HTRA1 gene were not significantly different between the RA patients and controls (P> 0.05). Haplotypes generated by these five SNPs did not show significantly difference between the two groups either (P> 0.05). Serum RF levels in the RA patients had no significant difference among the genotypes for four SNPs (rs2014307, rs2248799, rs714816, and rs2268356) in the HTRA1 gene, while RF levels in the RA patients with genotypes AA+AG of the rs2300433 locus were significantly higher than that in genotype GG carriers (P< 0.05). Serum CRP levels in the RA patients had no significant difference among the genotypes for all the five SNPs. Author's results suggested that although the five SNPs in the HTRA1 gene were not associated with RA in Chinese Han population, RF levels in the RA patients with genotypes AA and AG in the rs2300433 locus were significantly higher than the GG carriers. The HTRA1 role in RF regulation needs to be further investigated.

CFH, VEGF, and PEDF genotypes and the response to intravitreous injection of bevacizumab for the treatment of age-related macular degeneration.

We determined whether there is an association between complement factor H (CFH), high-temperature requirement A-1 (HTRA1), vascular endothelial growth factor (VEGF), and pigment epithelium-derived factor (PEDF) genotypes and the response to treatment with a single intravitreous injection of bevacizumab for age-related macular degeneration (AMD). Eighty-three patients with exudative AMD treated by bevacizumab injection were genotyped for three single nucleotide polymorphisms (SNPs; rs800292, rs1061170, rs1410996) in the CFH gene, a rs11200638-SNP in the HTRA1 gene, three SNPs (rs699947, rs1570360, rs2010963) in the VEGF gene, and four SNPs (rs12150053, rs12948385, rs9913583, rs1136287) in the PEDF gene using a TaqMan assay. The CT genotype (heterozygous) of CFH-rs1061170 was more frequently represented in nonresponders in vision than TT genotypes (nonrisk allele homozygous) at the time points of 1 and 3months, while there was no CC genotype (risk allele homozygous) in our study cohort (p = 7.66 × 10(-3), 7.83 × 10(-3), respectively). VEGF-rs699947 was also associated with vision changes at 1month and PEDF-rs1136287 at 3months (p = 5.11 × 10(-3), 2.05 × 10(-2), respectively). These variants may be utilized for genetic biomarkers to estimate visual outcomes in the response to intravitreal bevacizumab treatment for AMD.

Association of HTRA1 promoter polymorphism with spinal disc degeneration in Japanese women

HTRA1 (high-temperature requirement A1) has been implicated in the modulation of various disease pathologies. HTRA1 expression is upregulated in osteoarthritic joints, suggesting that it may contribute to the development of this debilitating disease. Moreover, recent reports have shown that the rs11200638, a single nucleotide polymorphism (SNP) in the promoter region of the HTRA1 gene, is strongly associated with an increased prevalence of age-related macular degeneration (AMD). In the present study, we examined the expression of the HTRA1 in human primary chondrocytes and an association between the rs11200638 SNP and radiographic features of spinal disc degeneration in 513 postmenopausal Japanese women. HTRA1 mRNA was detected and increased by TGF-beta treatment in human primary chondrocytes. As an association study of rs11200638 SNP in the HTRA1 gene, the subjects without the G allele (AA; n = 89) had a significantly higher spinal disc space narrowing score than the subjects bearing at least one G allele (GG + GA; n = 424) (P = 0.0292). We found that subjects without the G allele (AA) were significantly overrepresented in the subjects having a higher (> or =4) disc space narrowing score (P = 0.013; odds ratio 1.97; 95% confidence interval 1.15-3.37 by logistic regression analysis). A genetic variation at the HTRA1 gene promoter locus is associated with spinal disc degeneration, suggesting an involvement of the HTRA1 gene in osteoarthritis.

ANALYSES OF SINGLE NUCLEOTIDE POLYMORPHISMS AND HAPLOTYPE LINKAGE OF LOC387715 AND THE HTRA1 GENE IN EXUDATIVE AGE-RELATED MACULAR DEGENERATION IN A CHINESE COHORT

To investigate the effect of single nucleotide polymorphisms (SNPs) and haplotypes in the genes encoding age-related maculopathy susceptibility 2 (LOC387715/ARMS2) and high-temperature requirement A-1 (HTRA1) in a case-control study in a Chinese cohort of individuals with exudative age-related macular degeneration (AMD). We genotyped 2 SNPs, namely, LOC387715 rs10490924 and HTRA1 rs11200638, in 159 exudative AMD patients and 140 age- and sex-matched control subjects. All the four possible haplotypes of these two SNPs were detected. Comparisons of the risk genotypes and risk or protective haplotypes across multiple populations were performed. Allelic or genotype association tests yielded significant results at P < 0.001. We observed that homozygous risk genotypes (TT in rs10490924 and AA in rs11200638) were more strongly associated with AMD than the heterozygous genotypes (GT in rs10490924 and geographic atrophy in rs11200638) for both SNPs. Comparisons of the odds ratios for genotypes revealed that there is ethnic disparity in AMD prevalence, even within the Chinese population. The haplotype TA, comprising both the SNPs, was identified as an at-risk factor and was significantly associated with AMD, whereas the protective haplotype GG was significantly overrepresented in the controls (P < 0.001). The frequency of the TA haplotype was relatively higher in the Chinese population than in the white population in both groups, whereas the frequency of the GG haplotype was relatively lower in the Chinese controls than in the white and Japanese controls. Both SNPs are significantly associated with exudative AMD in the Chinese cohort and seem to contribute equally to the disease status. A higher frequency of homozygous risk genotypes and risk haplotype and a lower frequency of protective haplotype in the Chinese may be the cause of higher prevalence of exudative AMD in the Chinese than in the whites.

Association of the HTRA1 gene variant with age-related macular degeneration in the Japanese population

The purpose of this investigation was to determine whether the high-temperature requirement A-1 (HTRA1) gene polymorphism is associated with age-related macular degeneration (AMD) in native, unrelated Japanese patients. A total of 123 patients with AMD and 133 control subjects without AMD were recruited for this study. The single-nucleotide polymorphism (SNP) rs11200638 in the HTRA1 gene was assessed using a TaqMan assay. The risk A allele frequencies in the AMD cases and control patients were 0.577 and 0.380, respectively, and were associated with a significant risk of developing AMD (p=7.75x10(-6)). The results were more significant in subtype analyses with wet AMD (p=5.96x10(-7)). We conclude that the rs11200638 variant in the HTRA1 gene is strongly associated with AMD in the Japanese population. This result supports the hypothesis that the HTRA1 gene may increase susceptibility to AMD development and can participate in a potential new molecular pathway for AMD pathogenesis by extending this association across diverse ethnicities.