Molecular atlas of postnatal mouse heart development

Abstract

Rationale: Mammals lose the ability to regenerate their hearts within one week after birth. During this regenerative window, cardiac energy metabolism shifts from glycolysis to fatty acid oxidation, and recent evidence suggests that metabolism may participate in controlling cardiomyocyte cell cycle. However, the molecular mechanisms mediating the loss of postnatal cardiac regeneration are not fully understood.Objective: This study aims at providing an integrated resource of mRNA, protein and metabolite changes in the neonatal heart to identify metabolism-related mechanisms associated with the postnatal loss of regenerative capacity. Methods and Results: Mouse ventricular tissue samples taken on postnatal days 1, 4, 9 and 23 (P01, P04, P09 and P23, respectively) were analyzed with RNA sequencing (RNAseq) and global proteomics and metabolomics. Differential expression was observed for 8547 mRNAs and for 1199 of the 2285 quantified proteins. Furthermore, 151 metabolites with significant changes were identified. Gene ontology analysis, KEGG pathway analysis and fuzzy c-means clustering were used to identify biological processes and metabolic pathways either up-or downregulated on all three levels. Among these were branched chain amino acid degradation (upregulated at P23) and production of free saturated and monounsaturated medium-to long-chain fatty acids (upregulated at P04 and P09; downregulated at P23). Moreover, the HMG-CoA synthase (HMGCS)-mediated mevalonate pathway and ketogenesis were transiently activated. Pharmacological inhibition of HMGCS in primary neonatal rat ventricular cardiomyocytes reduced the percentage of BrdU+ cardiomyocytes, providing evidence that the mevalonate and ketogenesis routes may participate in regulating cardiomyocyte cell cycle. Conclusions: This is the first systems-level resource combining data from genome-wide transcriptomics with global quantitative proteomics and untargeted metabolomics analyses of the mouse heart throughout the early postnatal period. This integrated multi-level data of molecular changes associated with the loss of cardiac regeneration may open up new possibilities for the development of regenerative therapies.

Distinct regulation of cardiac fibroblast proliferation and transdifferentiation by classical and novel protein kinase C isoforms: possible implications for new antifibrotic therapies

“…Based on our previous RNA sequencing data (Talman et al, 2018a;Talman et al, 2018b), the main cPKCs and nPKCs expressed in adult mouse heart are α, δ, ε, and η, which coincides with the analysis from Schreiber et al (2001). Our present results indicate that the main cPKC isoform in mouse CFs is PKCα, moreover suggesting that PKCα regulates myofibroblast transdifferentiation.…”

“…We then analyzed PKC protein levels to verify the expression of selected isoenzymes in mouse CFs and to assess whether PMA or HMI-1b11 cause PKC down-regulation in our experimental design. Based on our previous RNA sequencing data (Talman et al, 2018a;Talman et al, 2018b), the main PKC isoforms expressed in mouse heart are α, δ, ε, η, and λ [the mouse homologue of human PKCι (Webb et al, 2000)] (Supplemental Fig. S2).…”

Cross-Sectional Transcriptional Analysis of the Aging Murine Heart

“…This research supports ongoing efforts to characterize the transcriptional signatures of aging and development. Recent similar works have attempted to characterize differential gene expression in the fetal human heart (Pervolaraki et al, 2018 ), the neonatal mouse heart (Talman et al, 2018 ), and the elderly mouse heart (Bartling et al, 2019 ) but none have investigated gene expression across the entirety of the mouse lifespan. The whole-lifespan view provides greater resolution than the two group comparisons (old vs. young) traditionally used in age-related gene expression studies (Bodyak et al, 2002 ; Lee et al, 2002 ; Bartling et al, 2019 ).…”

Downregulated developmental processes in the postnatal right ventricle under the influence of a volume overload

“…Both neonatal mouse and human cardiomyocytes possess strong proliferative potential but with increasing age, the proliferative potential of cardiomyocytes gradually disappears, and by adulthood, the proliferative capability is negligible [5][6][7][8]. To determine the molecular mechanisms that mediate postnatal loss of cardiomyocyte proliferation, Virpi et al combined transcriptomics with proteomic and metabolomic analyses in the early postnatal mouse heart (from postnatal day 1[P1] to P23) [9]. Although these authors developed the molecular atlas of postnatal cardiac development and highlighted the importance of metabolic pathways as potential targets for cardiomyocyte proliferation, the downregulated processes involved in postnatal ventricular development remain unclear.…”

“…Our current understanding of the development of cardiomyocytes after birth is derived from whole-ventricle analysis or left-ventricle analysis, and right-ventricular analysis is lacking [9,10]. As the left and right ventricles are quite different in their embryologic origins, molecular structures, and anatomical functions, the data derived from the whole ventricle or left ventricle cannot be directly applied to the right ventricle (RV) [11][12][13].…”