A remarkable adaptive paradigm of heart performance and protection emerges in response to marked cardiac-specific overexpression of ADCY8

Abstract

Adult (3 month) mice with cardiac-specific overexpression of adenylyl cyclase (AC) type VIII (TGAC8) adapt to an increased cAMP-induced cardiac workload (~30% increases in heart rate, ejection fraction and cardiac output) for up to a year without signs of heart failure or excessive mortality. Here, we show classical cardiac hypertrophy markers were absent in TGAC8, and that total left ventricular (LV) mass was not increased: a reduced LV cavity volume in TGAC8 was encased by thicker LV walls harboring an increased number of small cardiac myocytes, and a network of small interstitial proliferative non-cardiac myocytes compared to wild type (WT) littermates; Protein synthesis, proteosome activity, and autophagy were enhanced in TGAC8 vs WT, and Nrf-2, Hsp90α, and ACC2 protein levels were increased. Despite increased energy demands in vivo LV ATP and phosphocreatine levels in TGAC8 did not differ from WT. Unbiased omics analyses identified more than 2,000 transcripts and proteins, comprising a broad array of biological processes across multiple cellular compartments, which differed by genotype; compared to WT, in TGAC8 there was a shift from fatty acid oxidation to aerobic glycolysis in the context of increased utilization of the pentose phosphate shunt and nucleotide synthesis. Thus, marked overexpression of AC8 engages complex, coordinate adaptation 'circuity' that has evolved in mammalian cells to defend against stress that threatens health or life (elements of which have already been shown to be central to cardiac ischemic pre-conditioning and exercise endurance cardiac conditioning) that may be of biological significance to allow for proper healing in disease states such as infarction or failure of the heart.

Characterization of diverse populations of sinoatrial node cells and their proliferation potential at single nucleus resolution

“…Our studies focus on both biochemical and biophysical mechanisms. Ed list is an overview of many of the molecules that are known to be important in excitation, Ca 2+ cycling and contraction in cardiac cells [ [20] , [21] , [22] , [23] , [24] ]. The results confirmed the consistent characteristics of sinus node myocytes ( Supplementary Figure 7-9 ).…”

“…For example, fatty acid metabolism and nitrogen metabolism, and immune signaling pathways (AGE-RAGE signaling pathway, TGF-beta signaling pathway, hedgehog signaling pathway, and B cell receptor signaling pathway) were negatively enriched in sinus node myocytes [ 16 ]. Finally, we also identified two categories of proliferative cell types [ 16 ], (1) endocardial, epicardial, and epithelial cells, and (2) macrophages, consistent with chronic proliferation of non-cardiac myocytes [ 24 ]. Thus, our results expand the understanding of mouse SAN at single nucleus resolution and provides a segue for more in-depth future mechanistic studies.…”

Age-associated failure of efficient cardiac proteostatic adaptations to chronic cAMP-stress is associated with accelerated heart aging

“…Flash frozen tissue was homogenized as previously described 14 . Briefly, snap-frozen LVs were homogenized and lysed in ice cold RIPA buffer (Thermo Fisher Scientific: 25 mM Tris-HCl (pH 7.6), 150 mM NaCl, 1% NP-40, 1% sodium deoxycholate, 0.1% SDS) supplemented with a Halt protease inhibitor cocktail (Thermo Fisher Scientific), Halt phosphatase inhibitor cocktail (Thermo Fisher Scientific) and 1 mM phenylmethyl sulfonyl fluoride, using a Precellys homogenizer (Bertin Instruments) with a tissue homogenization kit CKMix (Bertin Instruments) at 4°C.…”

“…The isolation of protein aggregates and the assessment of protein aggregation was conducted using the Proteostat kit (Enzo Life Science, ENZ-51023), as previously published 14 . Specifically, 50 μg of proteins were loaded into a 96-well plate for analysis.…”

Pipeline for RNA sequencing data analysis by combination of Nextflow and R

“…Because of the advantages of different tools, the combination of various tools allows us to customize our bioinformatics analysis flexibly[9]. My pipeline was built by the combination of Nextflow nf-core rnaseq pipeline and R with many R packages.…”