Proteome signatures of reductive stress cardiomyopathy

Nuclear factor erythroid 2-related factor 2 (NRF2), a redox sensor, is vital for cellular redox homeostasis. We reported that transgenic mice expressing constitutively active Nrf2 (CaNrf2-TG) exhibit reductive stress (RS). In this study, we identified novel protein biomarkers for RS-induced cardiomyopathy using Tandem Mass Tag (TMT) proteomic analysis in heart tissues of TG (CaNrf2-TG) and non-transgenic (NTg) mice at 6-7 months of age (N= 4/group). A total of 1105 proteins were extracted from 22544 spectra. Of note, about 560 proteins were differentially expressed in TG vs. NTg hearts, indicating a global impact of RS on myocardial proteome. From a closer analysis of the proteome datasets, we identified over 32 proteins that were significantly altered in response to RS. Among these, 20 were upregulated and 12 were downregulated in the hearts of TG vs. NTg mice, suggesting that these proteins could be putative signatures of RS. Scaffold analysis revealed a clear distinction between TG vs NTg hearts. Of note, we observed several proteins with redox (#185; cysteine residues), NEM-adducts (#81), methionine-loss (#21) and acetylation (#1) modifications in TG vs. NTg hearts due to chronic RS. The majority of the differentially expressed proteins (DEPs) that are significantly altered in RS mice were found to be involved in stress related pathways such as antioxidants, NADPH, protein quality control (PQC), etc. Interestingly, proteins that were involved in mitochondrial respiration, lipophagy and cardiac rhythm were dramatically decreased in TG hearts. Of note, we identified the glutathione family of proteins as the significantly changed subset of the proteome in TG heart. Surprisingly, our comparative analysis of NGS based transcriptome and TMT-proteome indicated [~]50% of the altered proteins in TG myocardium was found to be negatively correlated with their transcript levels. Modifications at cysteine/NEM-adducts (redox), methionine or lysine residues in multiple proteins in response to chronic RS might be associated with impaired PQC mechanisms, thus causing pathological cardiac remodeling. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/460105v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@e5974borg.highwire.dtl.DTLVardef@12fe043org.highwire.dtl.DTLVardef@2c6e17org.highwire.dtl.DTLVardef@efb153_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG