Mitochondrial dysfunction in rheumatoid arthritis: A comprehensive analysis by integrating gene expression, protein-protein interactions and gene ontology data

PLoS One. 2019 Nov 8;14(11):e0224632. doi: 10.1371/journal.pone.0224632. eCollection 2019.

Abstract

Several studies have reported mitochondrial dysfunction in rheumatoid arthritis (RA). Many nuclear DNA (nDNA) encoded proteins translocate to mitochondria, but their participation in the dysfunction of this cell organelle during RA is quite unclear. In this study, we have carried out an integrative analysis of gene expression, protein-protein interactions (PPI) and gene ontology data. The analysis has identified potential implications of the nDNA encoded proteins in RA mitochondrial dysfunction. Firstly, by analysing six synovial microarray datasets of RA patients and healthy controls obtained from the gene expression omnibus (GEO) database, we found differentially expressed nDNA genes that encode mitochondrial proteins. We uncovered some of the roles of these genes in RA mitochondrial dysfunction using literature search and gene ontology analysis. Secondly, by employing gene co-expression from microarrays and collating reliable PPI from seven databases, we created the first mitochondrial PPI network that is specific to the RA synovial joint tissue. Further, we identified hubs of this network, and moreover, by integrating gene expression and network analysis, we found differentially expressed neighbours of the hub proteins. The results demonstrate that nDNA encoded proteins are (i) crucial for the elevation of mitochondrial reactive oxygen species (ROS) and (ii) involved in membrane potential, transport processes, metabolism and intrinsic apoptosis during RA. Additionally, we proposed a model relating to mitochondrial dysfunction and inflammation in the disease. Our analysis presents a novel perspective on the roles of nDNA encoded proteins in mitochondrial dysfunction, especially in apoptosis, oxidative stress-related processes and their relation to inflammation in RA. These findings provide a plethora of information for further research.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics
  • Arthritis, Rheumatoid / genetics*
  • Arthritis, Rheumatoid / pathology*
  • Gene Expression Profiling
  • Gene Expression Regulation*
  • Gene Ontology*
  • Humans
  • Inflammation / genetics
  • Inflammation / pathology
  • Mitochondria / pathology*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Models, Biological
  • Oxidative Phosphorylation
  • Protein Interaction Maps / genetics*
  • Reactive Oxygen Species / metabolism
  • Synovial Membrane / metabolism
  • Synovial Membrane / pathology

Substances

  • Mitochondrial Proteins
  • Reactive Oxygen Species

Grants and funding

We thank the department of Information Technology, Biotechnology and Science & Technology (IT, BT and S&T), Government of Karnataka, India for infrastructure support. VP received fellowships from the Institute of Bioinformatics and Applied Biotechnology (IBAB) as well as from the Council of Scientific and Industrial Research (CSIR), Government of India (GoI) (File No. 09/1086(0001)/2012-EMR-1), URL: http://www.csirhrdg.res.in/. SR is a faculty at IBAB. This project was partially supported by a grant from the Department of Biotechnology, GoI (BTPR12422/MED/31/287/2014, URL: http://www.dbtindia.nic.in/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.