FBLN5 Gene Research Articles

P106 Genome-Wide Association Study of a rare papulosquamous disease: pityriasis rubra pilaris

Abstract Pityriasis rubra pilaris (PRP) is a rare chronic skin disorder that causes persistent inflammation, thickening and shedding of the skin. In terms of classification, it is a papulosquamous disease and its clinical features that have the closest overlap with psoriasis. Genetic studies have thus far identified variants in the CARD14 gene that contribute to the susceptibility of PRP, but a genome-wide association study (GWAS) has not yet been conducted. Therefore, it was our aim to perform a GWAS using the genotype data of nearly 200 000 individuals available from the Estonian Biobank database (EstBB). The patients included 100 EstBB participants who had a registered ICD-10 diagnosis code for PRP–L44.0. The control group consisted of 199 647 individuals who did not have the L44.0 diagnosis. An additive GWAS was performed using the SAIGE program adjusting for age, sex, and the first 10 genetic principal components. Since the group of patients was smaller than typically used in GWAS, we lowered the threshold for statistical significance to P < 5 × 10−7. The FUMA platform was used for functional annotation of association signals. Significant associations appeared in genomic regions of chromosome 4 [single nucleotide polymorphism (SNP) rs115367424, P = 2.08 × 10−7], chromosome 6 (lead SNP rs142103230, P = 5.71 × 10−8) and chromosome 14 (lead SNP rs8012648, P = 2.44 × 10−7). The nearest gene to rs115367424 is CCSER1, which has been associated with poor melanoma survival. The candidate SNPs of chromosome 6 are situated within an intron of PRKN gene that functions as a modulator of innate immunity to infectious agents and its genetic variants have been associated with susceptibility to leprosy. Chromosome 14 candidate SNPs are intronic variants of FBLN5 gene that can promote dermal wound healing and attenuate burn injury-induced inflammatory responses. The results presented here require confirmation in future studies, and the identification of possible functional variants in the three discussed genomic regions calls for further investigation. Genetic research on PRP is challenging due to its very rare occurrence, but considering the severity of the disease, this scientific attention is still very much needed.

Extracellular SOD modulates canonical TNFα signaling and α5β1 integrin transactivation in vascular smooth muscle cells

TNFα activates NADPH oxidase 1 (Nox1) in vascular smooth muscle cells (VSMCs). The extracellular superoxide anion (O2•-) produced is essential for the pro-inflammatory effects of the cytokine but the specific contributions of O2•- to signal transduction remain obscure. Extracellular superoxide dismutase (ecSOD, SOD3 gene) is a secreted protein that binds to cell surface heparin sulfate proteoglycans or to Fibulin-5 (Fib-5, FBLN5 gene), an extracellular matrix protein that also associates with elastin and integrins. ecSOD converts O2•- to hydrogen peroxide (H2O2) which prevents NO• inactivation, limits generation of hydroxyl radical (OH•), and creates high local concentrations of H2O2. We hypothesized that ecSOD modifies TNFα signaling in VSMCs. Knockdown of ecSOD (siSOD3) suppressed downstream TNFα signals including MAPK (JNK and ERK phosphorylation) and NF-κB activation (luciferase reporter and IκB phosphorylation), interleukin-6 (IL-6) secretion, iNOS and VCAM expression, and proliferation (Sulforhodamine B assay, PCNA western blot). These effects were associated with significant reductions in the expression of both Type1 and 2 TNFα receptors. Reduced Fib-5 expression (siFBLN5) similarly impaired NF-κB activation by TNFα, but potentiated FAK phosphorylation at Y925. siSOD3 also increased both resting and TNFα-induced phosphorylation of FAK and of glycogen synthase kinase-3β (GSK3β), a downstream target of integrin linked kinase (ILK). These effects were dependent upon α5β1 integrins and siSOD3 increased resting sulfenylation (oxidation) of both integrin subunits, while preventing TNFα-induced increases in sulfenylation. To determine how ecSOD modified TNFα-induced inflammation in intact blood vessels, mesenteric arteries from VSMC-specific ecSOD knockout (KO) mice were exposed to TNFα (10 ng/ml) in culture for 48 h. Relaxation to acetylcholine and sodium nitroprusside was impaired in WT but not ecSOD KO vessels. Thus, ecSOD association with Fib-5 supports pro-inflammatory TNFα signaling while tonically inhibiting α5β1 integrin activation.

International Urogynecological Consultation (IUC): pathophysiology of pelvic organ prolapse (POP)

This manuscript is the International Urogynecology Consultation (IUC) on pelvic organ prolapse (POP) chapter one, committee three, on the Pathophysiology of Pelvic Organ Prolapse assessing genetics, pregnancy, labor and delivery, age and menopause and animal models. An international group of urogynecologists and basic scientists performed comprehensive literature searches using pre-specified terms in selected biomedical databases to summarize the current knowledge on the pathophysiology of the development of POP, exploring specificallyfactors including (1) genetics, (2) pregnancy, labor and delivery, (3) age and menopause and (4) non-genetic animal models. This manuscript represents the summary of three systematic reviews with meta-analyses and one narrative review, to which a basic scientific comment on the current understanding of pathophysiologic mechanisms was added. The original searches revealed over 15,000 manuscripts and abstracts which were screened, resulting in 202 manuscripts that were ultimately used. In the area of genetics the DNA polymorphisms rs2228480 at the ESR1 gene, rs12589592 at the FBLN5 gene, rs1036819 at the PGR gene and rs1800215 at the COL1A1 gene are significantly associated to POP. In the area of pregnancy, labor and delivery, the analysis confirmed a strong etiologic link between vaginal birth and symptoms of POP, with the first vaginal delivery (OR: 2.65; 95% CI: 1.81-3.88) and forceps delivery (OR: 2.51; 95% CI: 1.24-3.83) being the main determinants. Regarding age and menopause, only age was identified as a risk factor (OR : 1.102; 95% CI: 1.02-1.19) but current data do not identify postmenopausal status as being statistically associated with POP. In several animal models, there are measurable effects of pregnancy, delivery and iatrogenic menopause on the structure/function of vaginal support components, though not on the development of POP. Genetics, vaginal birth and age all have a strong etiologic link to the development of POP, to which other factors may add or protect against the risk.

New insight into clinical heterogeneity and inheritance diversity of FBLN5-related cutis laxa

BackgroundFBLN5-related cutis laxa (CL) is a rare disorder that involves elastic fiber-enriched tissues and is characterized by lax skin and variable systemic involvement such as pulmonary emphysema, arterial involvement, inguinal hernias, hollow viscus diverticula and pyloric stenosis. This type of CL follows mostly autosomal recessive (AR) and less commonly autosomal dominant patterns of inheritance.ResultsIn this study, we detected a novel homozygous missense variant in exon 6 of FBLN5 gene (c.G544C, p.A182P) by using whole exome sequencing in a consanguineous Iranian family with two affected members. Our twin patients showed some of the clinical manifestation of FBLN5-related CL but they did not present pulmonary complications, gastrointestinal and genitourinary abnormalities. The notable thing about this monozygotic twin sisters is that only one of them showed ventricular septal defect, suggesting that this type of CL has intrafamilial variability. Co-segregation analysis showed the patients’ parents and relatives were heterozygous for detected variation suggesting AR form of the CL. In silico prediction tools showed that this mutation is pathogenic and 3D modeling of the normal and mutant protein revealed relative structural alteration of fibulin-5 suggesting that the A182P can contribute to the CL phenotype via the combined effect of lack of protein function and partly misfolding-associated toxicity.ConclusionWe underlined the probable roles and functions of the involved domain of fibulin-5 and proposed some possible mechanisms involved in AR form of FBLN5-related CL. However, further functional studies and subsequent clinical and molecular investigations are needed to confirm our findings.

Autosomal recessive cutis laxa: a novel mutation in the FBLN5 gene in a family.

FBLN5-related cutis laxa (CL) is a rare syndrome that can be inherited in an autosomal dominant or recessive manner. Autosomal recessive cutis laxa (ARCL), type IA, has been reported to be more severe. The disease is characterized by microcephaly, sagging cheeks, loose, wrinkled and redundant skin, emphysema, aorta or pulmonary artery abnormalities, inguinal hernia, and anomalies of internal organs. Homozygous mutations in the FBLN5 gene are responsible for the clinical manifestations. We report a family study of a child with ARCL. FBLN5 genes of the patient and parents were sequenced using next-generation sequencing technologies. Analyses showed that the patient was homozygous for the novel c.518A>G, p.R173H mutation in exon 6 of the FBLN5 gene, whereas the parents were heterozygous. The mutation was found to be 'possibly pathogenic' in bioinformatic analysis. We identified a novel FBLN5 mutation in a CL patient; pedigree and parental genetic analyses suggested ARCL. Our results also suggest that the mutation analysis provides useful evidence to support the clinical diagnosis and define the inheritance mode of CL in an apparently sporadic case.

Novel FBLN5 Mutation of Congenital Autosomal Recessive Cutis Laxa With Isolated Right Ventricular Non-Compaction (RVNC): New Findings on Echocardiographic Speckle-Tracking Strain Imaging of RVNC

: We report on a novel mutation in a two-year-old child with autosomal recessive cutis laxa with severe generalized laxity of the skin, prematurely aged appearance, conjunctival chalasia, episodes of severe rectal prolapse, isolated right ventricular non-compaction, (RVNC), significant pulmonary hypertension at the systemic arterial pressure level, severe tricuspid regurgitation, corpulmonale secondary to recurrent pulmonary infections, and mixed pulmonary fibrosis and emphysema. Next generation sequencing of cutis laxa genes identified a novel homozygous mutation in the FBLN5 gene (homozygous sequence alteration of c.907C > T [p. Gin303*] FBLN5 [ENS0342058]). Despite severe and generalized disorder in the patient’s connective tissues, she had no primary valvar or vascular abnormalities in the heart. Complete speckle-tracking strain imaging (SI) by two-dimensional echocardiography showed decreased systolic longitudinal and transverse strain in the involved segment of the right ventricle (RV).

Overexpression of Fibulin-5 in Retinal Pigment Epithelial Cells Inhibits Cell Proliferation and Migration and Downregulates VEGF, CXCR4, and TGFB1 Expression in Cocultured Choroidal Endothelial Cells

Purpose of the study: Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss. Fibulin-5 (FBLN5) plays a pleiotropic role in the pathogenesis of AMD. We examined whether the in vitro overexpression of FBLN5 in retinal pigment epithelial (RPE) cells alters the proliferation and migration of cocultured choroidal endothelial cells (CECs) and explored the possible mechanisms involved.Materials and methods: A recombinant lentiviral vector carrying the Fbln5 gene was generated to transduce rat RPE cells. The expression of FBLN5 in transduced RPE cells was detected by quantitative real-time PCR and Western blot. The transduced RPE cells were then cocultured with rhesus macaque CECs in a Transwell coculture system. The impact of overexpression of FBLN5 in RPE cells on CEC proliferation and migration was assessed, as well as the impact on the mRNA expressions of vascular endothelial growth factor (VEGF), C-X-C chemokine receptor type 4 (CXCR4), and transforming growth factor β1 (TGFB1).Results: Our results showed that a recombinant lentivirus carrying the Fbln5 gene, which could induce overexpression of FBLN5 in RPE cells, was successfully generated. Overexpression of FBLN5 in RPE cells inhibited cell proliferation and migration and downregulated the mRNA expressions of VEGF, CXCR4, and TGFB1 in cocultured CECs.Conclusions: These findings suggest that FBLN5 may interfere with choroidal neovascularization by downregulating VEGF, CXCR4, and TGFB1 expression and inhibiting CEC proliferation and invasion, intensifying interest in FBLN5 as a target for therapeutic intervention in neovascular AMD.

Abstract 2781: Genetic variations in angiogenesis-related genes in prostate cancer aggressiveness

Abstract Prostate cancer is the most common cancer and the second leading cause of cancer death in American men. Clinicians usually face difficulties in distinguishing indolent and aggressive tumors at the time of prostate cancer diagnosis. Thus, there is an urgent need for finding biomarkers to predict prostate cancer prognosis in order to select a suitable treatment plan for prostate cancer patients. Angiogenesis, the development of new blood vessels, has been shown to be associated with Gleason score, tumor stage, progression, metastasis and survival in prostate cancer patients. We used 1,151 prostate cancer cases (492 non-aggressive and 659 aggressive) obtained from the Cancer Genetic Markers of Susceptibility (CGEMS) prostate cancer genome-wide data set. This objective of this study is to evaluate single nucleotide polymorphisms (SNPs) in the angiogenesis-related genes associated with prostate cancer aggressiveness. A total of 2,653 SNPs in 161 angiogenesis-related genes in the nonsex chromosomes were evaluated after excluding two SNPs, which were not followed the Hardy-Weinberg equilibrium in the control group. A patient with a Gleason score < 7 and stage < III was categorized into the non-aggressive group; while a patient with a Gleason score > 7 or stage > III was categorized into the aggressive group. The associations between prostate cancer aggressiveness and individual SNPs with different inheritance models (dominant, recessive, log-additive or genotypic model) were evaluated using logistic regression models. For each SNP, the minimum p-value among all testing inheritance models was selected. A total of 287 SNPs had raw-p values less than 0.05. Of the 287 SNPs, 89 SNPs had FDR q value less than 10%. Because the individual SNP analyses only considered one SNP associated with the outcome, we applied Random Forests (RF) analysis, a machine learning method, to explore important SNPs associated with prostate cancer aggressiveness though SNP-SNP interactions. RF provides the variable importance rank, which takes interactions into consideration. The top two SNPs in the univariate rank are rs1477908 (OR = 0.65, 95%CI=0.52-0.81, p=0.00017, log-additive model) and rs2616488 (OR=0.70, 95%CI=0.58-0.85, p=0.0002, log-additive model). Both SNPs were in the MMP16 gene and are also in the top one and five in the RF rank, respectively. Among top 10 SNPs in the RF ranking, 3 SNPs were in the FBLN5 gene. The RF (univariate) rank for these three SNPs (rs2498852, rs929608, and rs2052204) were 3 (8), 4 (31) and 9 (72). These data show that the impact of the SNPs in the FBLN5 gene was partially through interactions. Previous studies reported that the MMP16 and FBLN5 have different regulation in prostate cancer. This study suggests variants in angiogenesis-related genes, especially MMP16 and FBLN5, appear to influence prostate cancer aggressiveness. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2781. doi:10.1158/1538-7445.AM2011-2781

Cútis laxa: relato de caso

Cutis laxa is a rare inherited or acquired disorder of elastic tissue characterized by inelastic and loose skin. Congenital cutis laxa may present with internal organ involvement, determining a worse prognosis. The authors present the case of a female patient with clinical manifestations suggestive of the hereditary form of the disease, with consanguineous parents (second-degree cousins) and a brother who died with a similar clinical presentation. The genetic study of the FBLN5 gene was important to confirm the diagnosis, define the prognosis, and provide genetic counseling to the family.

Common polymorphisms of Fibulin-5 and the risk of abdominal aortic aneurysm development

Fibulin-5 is a crucial protein in the connective tissue structure of the aortic wall. The purpose of this study was to determine if genetic variation within the Fibulin-5 gene was associated with abdominal aortic aneurysms (AAA). AAA patients, with disease-free controls, were recruited and a past medical history questionnaire completed. Three single nucleotide polymorphisms (SNPs) in the FBLN5 gene (rs2498834, rs2430366 and rs2254320) were genotyped. The two cohorts were compared and haplotype analysis performed. A total of 230 AAA cases and 278 controls were successfully genotyped. The mean age was 71.9 years (+/- 6.8). No difference between cases and controls was found in the distribution of alleles of FBLN5 SNPs rs2498834 (p = 0.47), rs2430366 (p = 0.45) or rs2254320 (p = 0.46). Haplotype analysis did not reveal any significant difference. In conclusion, genetic variation within FBLN5 is unlikely to play any role in the development of AAA.

Defective protein glycosylation in patients with cutis laxa syndrome

Congenital cutis laxa is a genetically heterogeneous condition presenting with loose and redundant skin folds, decreased elasticity of the skin, connective tissue involvement and a highly variable spectrum of associated features. The most common forms are inherited in an autosomal recessive or dominant fashion. Fibulin 5 and elastin mutations were detected in a limited number of patients, but in most cases the etiology is not known. Based on a previous observation of an abnormal transferrin isoelectric focusing pattern in a patient with cutis laxa indicating an N-glycosylation defect, we performed a screening for disorders of protein glycosylation in unrelated children with cutis laxa syndrome, including a recently developed test for defective O-glycosylation. Here, we describe five patients from consanguineous marriages with a cutis laxa syndrome with skeletal and joint involvement, developmental delay and neurological findings. Three of these five children have an inborn error of glycan biosynthesis affecting the synthesis of both N- and O-linked glycans. Two patients had normal glycosylation patterns. All known causes of secondary glycosylation disorders were excluded in the children. No mutations were found in the FBLN5 gene. In conclusion, we have identified a new combined glycosylation defect with a distinct clinical phenotype. Our results suggest that a combined defect of glycosylation might be a causative factor in congenital cutis laxa. This is the first report where abnormal N- and O-linked glycosylation is implicated in the etiology of cutis laxa syndrome.

A combined defect in the biosynthesis of N- and O-glycans in patients with cutis laxa and neurological involvement: the biochemical characteristics

Based on our preliminary observation of abnormal glycosylation in a cutis laxa patient, nine cutis laxa patients were analyzed for congenital defects of glycosylation (CDG). Isoelectric focusing of plasma transferrin and apolipoproteinC-III showed that three out of nine patients had a defect in the biosynthesis of N-glycans and core 1 mucin type O-glycans, respectively. Mass spectrometric N-glycan analyses revealed a relative increase of glycans lacking sialic acid and glycans lacking sialic acid and galactose residues. Mutation analysis of the fibulin-5 gene (FBLN5), which has been reported in cases of autosomal recessive cutis laxa, revealed no mutations in the patients' DNA. Evidence is presented that extracellular matrix (ECM) proteins of skin are likely to be highly glycosylated with N- and/or mucin type O-glycans by using algorithms for predicting glycosylation. The conclusions in this study were that the clinical phenotype of autosomal recessive cutis laxa seen in three patients is not caused by mutations in the FBLN5 gene. Our findings define a novel form of CDG with cutis laxa and neurological involvement due to a defect in the sialylation and/or galactosylation of N- and O-glycans. Improper glycosylation of ECM proteins of skin may form the pathophysiological basis for the cutis laxa phenotype.