Project description:Heart disease is the leading cause of death as there is no current method to repair damaged myocardium due to the limited proliferative capacity of adult cardiomyocytes. Curiously, mouse neonates and zebrafish, larvae or adult, are able to regenerate their hearts via cardiomyocyte de-differentiation and proliferation. However, a molecular mechanism of why these cardiomyocytes can re-enter cell cycle is poorly understood. Here, we identify a unique metabolic state that primes adult zebrafish and neonatal mouse ventricular cardiomyocytes to proliferate. Zebrafish and neonatal mouse hearts display elevated glutamine levels, predisposing them to amino acid-driven activation of TOR. We show that this TOR activation is required for zebrafish cardiomyocyte regeneration in vivo. After injury we observe pS6 in both the epicardium and ventricular cardiomyocytes suggesting these are amino acid primed cells necessary for regeneration. Through single cell and system-wide RNA-sequencing, LQC proteomics and microscopy we identify dramatic metabolic and mitochondrial changes during the first week of regeneration. These data suggest that regeneration of zebrafish myocardium is driven by metabolic remodeling and reveals a unique metabolic regulator, TOR-primed state, in which zebrafish and mammalian cardiomyocytes are regeneration competent.
Project description:Heart disease is the leading cause of death as there is no current method to repair damaged myocardium due to the limited proliferative capacity of adult cardiomyocytes. Curiously, mouse neonates and zebrafish, larvae or adult, are able to regenerate their hearts via cardiomyocyte de-differentiation and proliferation. However, a molecular mechanism of why these cardiomyocytes can re-enter cell cycle is poorly understood. Here, we identify a unique metabolic state that primes adult zebrafish and neonatal mouse ventricular cardiomyocytes to proliferate. Zebrafish and neonatal mouse hearts display elevated glutamine levels, predisposing them to amino acid-driven activation of TOR. We show that this TOR activation is required for zebrafish cardiomyocyte regeneration in vivo. After injury we observe pS6 in both the epicardium and ventricular cardiomyocytes suggesting these are amino acid primed cells necessary for regeneration. Through single cell and system-wide RNA-sequencing, LQC proteomics and microscopy we identify dramatic metabolic and mitochondrial changes during the first week of regeneration. These data suggest that regeneration of zebrafish myocardium is driven by metabolic remodeling and reveals a unique metabolic regulator, TOR-primed state, in which zebrafish and mammalian cardiomyocytes are regeneration competent.
Project description:For a short period of time in mammalian neonates, the mammalian heart can regenerate via cardiomyocyte proliferation. This regenerative capacity is largely absent in adults. In other organisms, including zebrafish, damaged hearts can regenerate throughout their lifespans. Many studies have been performed to understand the mechanisms of cardiomyocyte de-differentiation and proliferation during heart regeneration however, the underlying reason why adult zebrafish and young mammalian cardiomyocytes are primed to enter cell cycle have not been identified. Here we show the primed state of a pro-regenerative cardiomyocyte is dictated by its amino acid profile and metabolic state. Adult zebrafish cardiomyocyte regeneration is a result of amino acid-primed mTOR activation. Zebrafish and neonatal mouse cardiomyocytes display elevated glutamine levels, predisposing them to amino acid-driven activation of mTORC1. Injury initiates Wnt/β-catenin signalling that instigates primed mTORC1 activation, Lin28 expression and metabolic remodeling necessary for zebrafish cardiomyocyte regeneration. These studies reveal a unique mTORC1 primed state in zebrafish and mammalian regeneration competent cardiomyocytes.
Project description:Global proteomics data captured from P8 hearts, 7 days post-MI or sham surgery. Hearts were treated at 4, 5, and 6 days post surgery with saline or rapamycin.
Project description:Zebrafish is capable of endogenously regenerating functional retina pigment epithelium (RPE) after widespread genetic ablation which involves a series of cellular and molecular events that remain to be defined. Here, using the RPE genetic ablation model in zebrafish, we observed that mTOR signaling was activated in the RPE cells post-ablation. Pharmacological and genetic inhibition of mTOR signaling impaired RPE regeneration, while activation of mTOR signaling benefited RPE recovery, suggesting mTOR signaling was required and sufficient for RPE regeneration post-ablation in zebrafish. We further identified an interesting crosstalk between mTOR signaling and microglia/macrophages during RPE regeneration that mTOR acts as an upstream regulator of microglia/macrophage infiltration to the injury site while microglia/macrophage, in turn, rainenforce mTOR activity.
