Dataset Information

Repeat-Associated Non-ATG (RAN) Translation in Fuchs' Endothelial Corneal Dystrophy.

ABSTRACT: Purpose:The strongest genetic association with Fuchs' endothelial corneal dystrophy (FECD) is the presence of an intronic (CTG·CAG)n trinucleotide repeat (TNR) expansion in the transcription factor 4 (TCF4) gene. Repeat-associated non-ATG (RAN) translation, an unconventional protein translation mechanism that does not require an initiating ATG, has been described in many TNR expansion diseases, including myotonic dystrophy type 1 (DM1). Given the similarities between DM1 and FECD, we wished to determine whether RAN translation occurs in FECD. Methods:Antibodies against peptides in the C-terminus of putative RAN translation products from TCF4 were raised and validated by Western blotting and immunofluorescence (IF). CTG·CAG repeats of various lengths in the context of the TCF4 gene were cloned in frame with a 3× FLAG tag and transfected in human cells. IF with antipeptide and anti-FLAG antibodies, as well as cytotoxicity and cell proliferation assays, were performed in these transfected cells. Corneal endothelium derived from patients with FECD was probed with validated antibodies by IF. Results:CTG·CAG repeats in the context of the TCF4 gene are transcribed and translated via non-ATG initiation in transfected cells and confer toxicity to an immortalized corneal endothelial cell line. An antipeptide antibody raised against the C-terminus of the TCF4 poly-cysteine frame recognized RAN translation products by IF in cells transfected with CTG·CAG repeats and in FECD corneal endothelium. Conclusions:Expanded CTG·CAG repeats in the context of the third intron of TCF4 are transcribed and translated via non-ATG initiation, providing evidence for RAN translation in corneal endothelium of patients with FECD.

SUBMITTER: Soragni E

PROVIDER: S-EPMC5886103 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Repeat-Associated Non-ATG (RAN) Translation in Fuchs' Endothelial Corneal Dystrophy.

Soragni Elisabetta E Petrosyan Lina L Rinkoski Tommy A TA Wieben Eric D ED Baratz Keith H KH Fautsch Michael P MP Gottesfeld Joel M JM

Investigative ophthalmology & visual science 20180401 5

<h4>Purpose</h4>The strongest genetic association with Fuchs' endothelial corneal dystrophy (FECD) is the presence of an intronic (CTG·CAG)n trinucleotide repeat (TNR) expansion in the transcription factor 4 (TCF4) gene. Repeat-associated non-ATG (RAN) translation, an unconventional protein translation mechanism that does not require an initiating ATG, has been described in many TNR expansion diseases, including myotonic dystrophy type 1 (DM1). Given the similarities between DM1 and FECD, we wis ...[more]

PMID: 29677349

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Project description:Purpose To develop a model to predict corneal improvement after Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial corneal dystrophy (FECD) from Scheimpflug tomography. Design Cross-sectional study. Participants Forty-eight eyes (derivation group) and 45 eyes (validation group) with a range of severity of FECD undergoing DMEK. Methods Scheimpflug images were obtained before and after DMEK. Before DMEK, pachymetry map and posterior elevation map patterns were quantified by a special image analysis program measuring tomographic features of edema (loss of regular isopachs, displacement of the thinnest point of the cornea, posterior surface depression). Image-derived novel parameters were combined with instrument-derived parameters, and the relative influences of parameters associated with the change in central corneal thickness (CCT) after DMEK in the derivation group were determined by using a gradient boosting machine learning model. The parameters with highest relative influence were then fit in a linear regression model. The derived model was applied to the validation group. Correlations and agreement were assessed between predicted and observed changes in CCT. Main Outcome Measures Predictive power (R2) and mean difference between predicted and observed change in CCT. Results The gradient boosting machine model identified 4 novel parameters of isopach circularity and eccentricity and 1 instrument-derived parameter (posterior surface radius); preoperative CCT was a poor predictor. In the derivation group, the model strongly predicted the change in CCT after DMEK (R2 = 0.80; 95% confidence interval [CI], 0.71–0.89) and the mean difference between predicted and observed change was, by definition, 0 μm. When the same 5 parameters were fit to the validation group, the model performed very highly (R2 = 0.89; 95% CI, 0.84–0.94). When the coefficient estimates from the derivation model were used to predict the change in CCT in the validation group, the predictive power was also high (R2 = 0.78; 95% CI, 0.68–0.88), and the mean difference was 4 μm (predicted minus observed). Conclusions Scheimpflug tomography maps of corneas with FECD can predict the improvement in CCT after DMEK, independent of preoperative corneal thickness measurement. The model could be applied in clinical practice or for clinical research of FECD.

Dataset Information

Repeat-Associated Non-ATG (RAN) Translation in Fuchs' Endothelial Corneal Dystrophy.

Publications

Repeat-Associated Non-ATG (RAN) Translation in Fuchs' Endothelial Corneal Dystrophy.

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