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Heterozygous NTF4 mutations impairing neurotrophin-4 signaling in patients with primary open-angle glaucoma.

ABSTRACT: Glaucoma, a main cause of blindness in the developed world, is characterized by progressive degeneration of retinal ganglion cells (RGCs), resulting in irreversible loss of vision. Although members of the neurotrophin gene family in various species are known to support the survival of numerous neuronal populations, including RGCs, it is less clear whether they are also required for survival and maintenance of adult neurons in humans. Here, we report seven different heterozygous mutations in the Neurotrophin-4 (NTF4) gene accounting for about 1.7% of primary open-angle glaucoma patients of European origin. Molecular modeling predicted a decreased affinity of neurotrophin 4 protein (NT-4) mutants with its specific tyrosine kinase receptor B (TrkB). Expression of recombinant NT-4 carrying the most frequent mutation was demonstrated to lead to decreased activation of TrkB. These findings suggest a pathway in the pathophysiology of glaucoma through loss of neurotrophic function and may eventually open the possibility of using ligands activating TrkB to prevent the progression of the disease.

SUBMITTER: Pasutto F

PROVIDER: S-EPMC2756554 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Heterozygous NTF4 mutations impairing neurotrophin-4 signaling in patients with primary open-angle glaucoma.

Pasutto Francesca F Matsumoto Tomoya T Mardin Christian Y CY Sticht Heinrich H Brandstätter Johann H JH Michels-Rautenstrauss Karin K Weisschuh Nicole N Gramer Eugen E Ramdas Wishal D WD van Koolwijk Leonieke M E LM Klaver Caroline C W CC Vingerling Johannes R JR Weber Bernhard H F BH Kruse Friedrich E FE Rautenstrauss Bernd B Barde Yves-Alain YA Reis André A

American journal of human genetics 20090917 4

Glaucoma, a main cause of blindness in the developed world, is characterized by progressive degeneration of retinal ganglion cells (RGCs), resulting in irreversible loss of vision. Although members of the neurotrophin gene family in various species are known to support the survival of numerous neuronal populations, including RGCs, it is less clear whether they are also required for survival and maintenance of adult neurons in humans. Here, we report seven different heterozygous mutations in the ...[more]

PMID: 19765683

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Project description:The total RNA from control and POAG optic nerve lamina cribrosa region was isolated and subjected to analysis on U133A 2.0 affymetrix microarray chip. The results from these two analysis was compared to determine whether PAD II RNA level is altered. Purpose of the study. This study was done to determine which RNA transcripts undergo significant changes in the optic nerve between normal and cadaver primary open-angle glaucoma donors. Using donor tissues from NDRI we have performed proteomic analyses (which will be published shortly), we intend a comparison between the proteomic and RNA changes for select proteins in our study. Sample Collection and Preparation of Labeled Copy RNA; The total RNA from optic nerve was obtained using TRIZOL (Invitrogen Inc., Carlsbad, CA) with modification of recommended protocols. The optic nerve from donor eyes were carefully excised and minced into small pieces first using a scissor and then a scalpel. Prior to use tissue was washed with DEPC water and all solutions were prepared in DEPC water. The minced tissue was placed in a glass homogenizer with 1 ml TRIZOL per 100 mg of tissue and homogenized in a glass homogenizer DUALL 20 (Kimble Kontes Glass Co, Vineland, NJ) with 10 strokes cycles each at room temperature and after freezing with liquid nitrogen for 1 min for 40 cycles. This RNA was extracted with chloroform, isoamylalcohol and precipitated with sodium citrate/sodium chloride and isopropanol. The final air-dried RNA precipitate was suspended in DEPC water and stored in â??80oC prior to use. RNA was prepared for hybridization according to the GeneChip Expression Analysis Technical Manual (Affymetrix, Santa Clara, CA). The hybridization was performed at Gene Expression Array Core Facility at Case Western Reserve University (www.geacf.net). The RNA sample was cleaned using a column from a Qiagen RNeasy kit, (part # 74104 ) in accordance with the manufacturerâ??s instructions. The volume of DEPC water used to elute the RNA from the Qiagen column was dictated by the nominal mass of the loaded RNA sample. Samples were eluted in 100ml of water, precipitated with 0.5 volume of 7.5M Ammonium Acetate and 2.5 volumes of 100% ethanol at -20oC for 1 hr and centrifuged for 10 min at room temperature. The pellet was drained and washed twice in 500Âµl of 70% ethanol. Supernatant was aspirated. The pellet was dried briefly (less than 1 min) in a speeedvac (Savant) and re-suspended in a small volume (~ 12â??15ml) of DEPC water. A small aliquot (2ml) of the sample was used for quantitation. Cleaned RNA samples were annotated as â??clnRNAâ?? and stored at -20oC. cDNA Synthesis; The protocol recommended by Affymetrix Inc. for cDNA synthesis was used at all times. The reaction was primed by annealing an oligo-dT primer coupled to a T7 RNA polymerase promoter to the RNA sample. Whenever possible, 8 mg of clnRNA were reverse transcribed using Superscript II reverse transcriptase in a 20ml reaction at 42oC for 1 hr. Second strand synthesis was carried out immediately in a total reaction volume of 150ml in the presence of E. coli DNA polymerase I, RNAse H and DNA ligase. The reaction mixture incubated for 2 hrs at 16oC and for a further 5 min in the presence of T4 DNA pol.. The reaction was terminated by the addition of EDTA. The sample was cleaned with a Qiagen cDNA clean-up column according to the manufacturers directions. The elution buffer volume was 14ml. The eluted samples were stored overnight at -20oC. In-Vitro Transcription (IVT) reaction; In a 0.5ml microfuge tube, complementary RNA (cRNA) was generated in an IVT reaction using a BioArray High Yield ENZO kit (Affymetrix). The 40ml reaction contained 10ml of cDNA sample and was incubated at 37oC in the heating block for 4-5hrs. Samples were mixed by flicking, pulse-centrifuged and returned to the incubator once every 40 minutes. Upon completion of the reaction, IVT samples were adjusted to a volume of 100ml with DEPC-treated water and cleaned using Qiagen RNA clean-up columns. Samples were eluted in 45ml of DEPC-treated water. A 2ml-aliquot was used for quantitation. Corrected concentrations of cRNA (minus the input clnRNA) were determined. A standard fragmentation reaction volume was 40ml in a 0.5 ml microfuge tube and used 20mg of overall IVT RNA in 1X fragmentation buffer (40mM Tris acetate, pH 8.1, 100mM KOAc, 30mM MgOAc). The reaction was incubated at 94oC for 35min in a heat block. After the 35 min incubation the fragmented samples were placed on ice. The standard hybridization cocktail volume was 300ml. 150ml of 2X hybridization buffer was added (final concentrations : 100mM MES, 1M [Na+], 20mM EDTA, 0.01% Tween 20) Herring sperm and acetylated BSA were added to a final concentration of 0.1 and 0.5mg/ml respectively. The amount of fragmentation reaction containing 15mg of cRNA was added to the cocktail and the remaining volume was made up with molecular biology grade water. A 15ml aliquot of a 20X mixture of in-vitro transcripts of bacterial genes BioB BioC BioD and cre as external controls (spikes) were added to the cocktail to give final concentrations of 1.5, 5, 25 and 100pM respectively. Control oligonucleotide (5ml) was added to a final concentration of 50pM. Array Hybridization; Sample Hyridization cocktails (300ml) were removed from storage at â??20oC and thawed in a 45oC temperature block. The samples were incubated at 45oC for 5 min, incubated at 45oC for 5 min and then centrifuged at 15,000g for 5 min. 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Samples were retrieved from the chips and stored again in a freezer at -20oC. The chips were filled with buffer A and placed in a module of Fluidics 400 wash station. The chips were subjected to the Affymetrix â??EuKws4 ver 2â?? programmed series of stringent post hybridization washes, staining and post-staining washes in accordance with Affy protocols. Upon completion of the wash series (approximately 2 hrs), the chips were removed from the Fluidics station. The chips were inspected. Chips were scanned using an Agilent Gene Array scanner 3000 driven by Affymetrix GCOS software. Generation of Expression Values; Microarray Suite, version 5 (Affymetrix), was used to generate *.cel files, and a computer program (Probe Profiler, ver. 1.3.11; Corimbia Inc., Berkeley, CA) developed specifically for the GeneChip system (Affymetrix) was used to convert intensity data into quantitative estimates of gene expression for each probe set. The software identifies informative probe pairs, and down-weights the signal contribution of probe pairs that are subject to differential cross-hybridization effects or that consistently produce no signal. The software also detects and corrects for saturation artifacts, outliers, and chip defects. A probability statistic was generated for each probe set. The probability is associated with the null hypothesis that the expression level of the probe set is equal to zero (background). Genes not significantly expressed above background in any of the samples (P > 0.05) were

Dataset Information

Heterozygous NTF4 mutations impairing neurotrophin-4 signaling in patients with primary open-angle glaucoma.

Publications

Heterozygous NTF4 mutations impairing neurotrophin-4 signaling in patients with primary open-angle glaucoma.

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