Proteomic and phosphoproteomic profiling in heart failure with preserved ejection fraction (HFpEF)
Authors: Valero-Munoz M , Saw E L , Heckman R M , Blum B , Emili A , Sam F 
Published: October 2022

Abstract

Background
The lack of therapies for HFpEF patients is a major unmet need, thus identifying cardiac specific pathways in HFpEF is a priority.

Purpose
Identify molecular features of protein and phosphoprotein in a murine model of HFpEF

Methods
Studies followed the principles of laboratory animal care (NIH Pub no. 85–23 revised 1985). HFpEF (N=4) was induced by NaCl drinking water, unilateral nephrectomy, and chronic aldosterone infusion (SAUNA) or saline (Sham; N=4) for 4 wks. Mice were euthanized and LV tissue was collected. Samples were homogenized, proteins extracted and subjected to digestion followed by phosphopeptide enrichment for proteomics and phosphoproteomics profiling.

Results
HFpEF mice had moderate hypertension (137.8±7.0 vs. Sham; 115.4±6.0mmHg; P&lt;0.05), lung congestion (4.5±0.1 vs. 4.0±0.1; P&lt;0.01), and LVH (3.7±0.1 vs. 3.3±0.1mg/g; P&lt;0.05). ECHO showed normal LVEF with evidence of diastolic dysfunction in HFpEF mice. Mitral E velocity was reduced (1347±154 vs. 1971±284mm/s; P&lt;0.05) and IVRT increased (24.3±2.6 vs. 14.4±1.6ms; P&lt;0.05) vs. Sham. Protein and protein phosphosites from the LV were quantified by mass spectrometry. Analysis of the proteomics datasets revealed marked changes in sarcomere proteins, such as skeletal alpha (α)-actin (ACTA1; P=0.000039), beta (β)-myosin heavy chain (MYH7; P=0.006963) and myosin heavy chain 9 (MYH9; P=0.000408); the mitochondria-related proteins mitofusin 1 (MFN1; P=0.001059), mitochondrial dynamin like GTPase (aka optic atrophy protein 1, OPA1; P=0.046441) and transcription factor A mitochondrial (TFAM; P=0.005837); and the NAD-dependent protein deacetylase sirtuin-3 (SIRT3; P=0.000914). There was also a reduction in proteins involved in the oxidation of free fatty acid, pyruvate, and ketone bodies in the LV from HFpEF vs. Sham. Phosphoproteomics analysis also showed aberrant protein phosphorylation patterns linked to disparate subcellular compartments, ranging from sarcomere proteins (LIM domain-binding protein 3, LDB3; myozenin 2, Myoz2; titin, TTN), to nuclear-localized proteins (BAG family molecular chaperone regulator 3, BAG3; high mobility group protein HMG-I/HMG-Y, HMGA1) with known links to contractile dysfunction, LVH and/or cardiomyopathy. Additional GSEA analysis revealed the most relevant and enriched biological annotations in LV from HFpEF, to be processes involving immune system modulation and muscle contraction. Downregulated pathways were mainly related to multitude of GO terms associated with mitochondrial metabolism.

Conclusion(s)
This study presents the systematic, quantitative proteomics and phosphoproteomic analysis of the LV from the SAUNA HFpEF mice. We observed profound changes in proteins related to mitochondrial metabolism and function and heart contractile dysfunction in HFpEF which may be mediated by Sirtuin 3. Additional studies are warranted to investigate the specific role of Sirtuin 3 in mitochondrial metabolism and heart contractile dysfunction in HFpEF.

Funding Acknowledgement
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): National Institute of Heath (NIH/ NHLBI)