Quantitative Proteomics of Human Heart Samples Collected In Vivo Reveal the Remodeled Protein Landscape of Dilated Left Atrium Without Atrial Fibrillation

Nora Linscheid,Pi Camilla Poulsen,Ida Dalgaard Pedersen,Emilie Gregers,Jesper Hastrup Svendsen,Morten Salling Olesen,Jesper Velgaard Olsen,Mario Delmar,Alicia Lundby

doi:10.1074/mcp.ra119.001878

Abstract

Genetic and genomic research has greatly advanced our understanding of heart disease. Yet, comprehensive, in-depth, quantitative maps of protein expression in hearts of living humans are still lacking. Using samples obtained during valve replacement surgery in patients with mitral valve prolapse (MVP), we set out to define inter-chamber differences, the intersect of proteomic data with genetic or genomic datasets, and the impact of left atrial dilation on the proteome of patients with no history of atrial fibrillation (AF).We collected biopsies from right atria (RA), left atria (LA) and left ventricle (LV) of seven male patients with mitral valve regurgitation with dilated LA but no history of AF. Biopsy samples were analyzed by high-resolution mass spectrometry (MS), where peptides were pre-fractionated by reverse phase high-pressure liquid chromatography prior to MS measurement on a Q-Exactive-HF Orbitrap instrument. We identified 7,314 proteins based on 130,728 peptides. Results were confirmed in an independent set of biopsies collected from three additional individuals. Comparative analysis against data from post-mortem samples showed enhanced quantitative power and confidence level in samples collected from living hearts. Our analysis, combined with data from genome wide association studies suggested candidate gene associations to MVP, identified higher abundance in ventricle for proteins associated with cardiomyopathies and revealed the dilated LA proteome, demonstrating differential representation of molecules previously associated with AF, in non-AF hearts.This is the largest dataset of cardiac protein expression from human samples collected in vivo It provides a comprehensive resource that allows insight into molecular fingerprints of MVP and facilitates novel inferences between genomic data and disease mechanisms. We propose that over-representation of proteins in ventricle is consequent not to redundancy but to functional need, and conclude that changes in abundance of proteins known to associate with AF are not sufficient for arrhythmogenesis.

Highlights

Protein quantification from freshly collected biopsies is preferential to necropsy samples because of unspecific post-mortem protein degradation in the latter
Details related to patients in the replication cohort as well as related to a patient with atrial fibrillation are included in the same table
The present study provides the largest dataset of cardiac protein expression evaluated from human samples collected in vivo

Summary

Introduction

Protein quantification from freshly collected biopsies is preferential to necropsy samples because of unspecific post-mortem protein degradation in the latter. Increased abundances of proteins associated with sustained atrial fibrillation are not a sufficient condition to generate the disease state. Protein abundance differences between atria and ventricle primarily originate at the level of gene regulation and reflect a functional need. Genetic and genomic research has greatly advanced our understanding of heart disease. Comprehensive, indepth, quantitative maps of protein expression in hearts of living humans are still lacking. Using samples obtained during valve replacement surgery in patients with mitral valve prolapse (MVP), we set out to define inter-chamber differences, the intersect of proteomic data with genetic or genomic datasets, and the impact of left atrial dilation on the proteome of patients with no history of atrial fibrillation (AF)

Methods

Results

Discussion

Conclusion