Phosphoproteomic Analysis of Neonatal Regenerative Myocardium Revealed Important Roles of Checkpoint Kinase 1 via Activating Mammalian Target of Rapamycin C1/Ribosomal Protein S6 Kinase b-1 Pathway

Abstract

Background: In mammals, regenerative therapy after myocardial infarction is hampered by the limited regenerative capacity of adult heart, whereas a transient regenerative capacity is maintained in the neonatal heart. Systemic phosphorylation signaling analysis on ischemic neonatal myocardium might be helpful to identify key pathways involved in heart regeneration. Our aim was to define the kinase-substrate network in ischemic neonatal myocardium and to identify key pathways involved in heart regeneration after ischemic insult. Methods: Quantitative phosphoproteomics profiling was performed on infarct border zone of neonatal myocardium, and kinase-substrate network analysis revealed 11 kinases with enriched substrates and upregulated phosphorylation levels, including checkpoint kinase 1 (CHK1) kinase. The effect of CHK1 on cardiac regeneration was tested on Institute of Cancer Research CD1 neonatal and adult mice that underwent apical resection or myocardial infarction. Results: In vitro, CHK1 overexpression promoted whereas CHK1 knockdown blunted cardiomyocyte proliferation. In vivo, inhibition of CHK1 hindered myocardial regeneration on resection border zone in neonatal mice. In adult myocardial infarction mice, CHK1 overexpression on infarct border zone upregulated mammalian target of rapamycin C1/ribosomal protein S6 kinase b-1 pathway, promoted cardiomyocyte proliferation, and improved cardiac function. Inhibiting mammalian target of rapamycin activity by rapamycin blunted the neonatal cardiomyocyte proliferation induced by CHK1 overexpression in vitro. Conclusions: Our study indicates that phosphoproteome of neonatal regenerative myocardium could help identify important signaling pathways involved in myocardial regeneration. CHK1 is found to be a key signaling responsible for neonatal regeneration. Myocardial overexpression of CHK1 could improve cardiac regeneration in adult hearts by activating the mammalian target of rapamycin C1/ribosomal protein S6 kinase b-1 pathway. Thus, CHK1 might serve as a potential novel target in myocardial repair after myocardial infarction.

AHLF: ad hoc learning of peptide fragmentation from mass spectra enables an interpretable detection of phosphorylated and cross-linked peptides

“…We evaluate our approach on previously published phosphoproteomic data. This includes data sets from more than one hundred public repositories [4] and additionally validate these results on recently published data [26, 27, 28, 29, 30] and in case of cross-linking data we use previously published data to evaluate our transfer learning approach [31, 32, 33].…”

“…For validation we use five data sets [28, 29, 30, 26, 27]. For each data set, we used the original search results from MaxQuant alongside the raw spectra.…”

Dynamic Patterns of N6‐Methyladenosine Profiles of Messenger RNA Correlated with the Cardiomyocyte Regenerability during the Early Heart Development in Mice

“…Previous studies have shown that the proliferation and regeneration ability of heart tissue basically disappears around the 7 th day of development, and the cell cycle of cardiomyocytes no longer exists, with only a very small proliferation rate remaining [ 12 – 14 ]. The underlying mechanism is still unclear.…”

“…Unlike the adult zebrafish, the CMs of neonatal mice possess the proliferative capability and maintain the competence to renovate their damaged cardiac muscle tissue during the first 7 days of life [11,12]. Convincing evidence shows that heart regeneration in neonatal mice is achieved by cardiomyocyte proliferation and the cardiac developmental program for self-renewal [12][13][14]. The underlying mechanisms of neonatal cardiac proliferation remain largely unclear, but the related research is of crucial significance for discovering therapeutic targets for cardiomyocyte regeneration and cardiac repair.…”

Novel insight from the first lung transplant of a COVID‐19 patient

“…Tissue samples from different regions of the lungs were subjected to protein extraction and digestion according to previous methods. 16 The peptides were labelled, mixed and desalted by tC18 Sep-Pak column (Waters, USA).…”