Project description:Cardiomyocytes are highly metabolic cells responsible for generating the contractile force that drives heart function. During fetal development and regeneration, these cells undergo active division but lose their proliferation activity in the adult heart. The mechanisms that coordinate their metabolism and proliferation are not fully understood. Here, we study the developmental functions of the transcription factor NFYa, which we previously identified from regenerating cardiomyocytes. We show that loss of NFYa profoundly alters cardiomyocyte composition, with a decrease in immature regenerative cells and an increase in trabecular and mature cardiomyocytes, as revealed by spatial and single-cell transcriptome analyses. NFYa-deleted cardiomyocytes exhibited reduced proliferation and impaired mitochondrial metabolism, contributing to the cardiac growth defect. NFYa acts as a transcriptional activator of mitochondrial metabolic genes as well as cell-cycle genes in cardiomyocytes through its interaction with the cofactor SP2, providing a direct link between metabolism and proliferation at the gene transcriptional level. Our study reveals a key role of NFYa in regulating cardiac growth before birth and a previously unrecognized transcriptional control mechanism of metabolic genes in the heart, and highlights the importance of mitochondrial metabolism during fetal heart development and regeneration.
Project description:Cardiomyocytes are highly metabolic cells responsible for generating the contractile force that drives heart function. During fetal development and regeneration, these cells undergo active division but lose their proliferation activity in the adult heart. The mechanisms that coordinate their metabolism and proliferation are not fully understood. Here, we study the developmental functions of the transcription factor NFYa, which we previously identified from regenerating cardiomyocytes. We show that loss of NFYa profoundly alters cardiomyocyte composition, with a decrease in immature regenerative cells and an increase in trabecular and mature cardiomyocytes, as revealed by spatial and single-cell transcriptome analyses. NFYa-deleted cardiomyocytes exhibited reduced proliferation and impaired mitochondrial metabolism, contributing to the cardiac growth defect. NFYa acts as a transcriptional activator of mitochondrial metabolic genes as well as cell-cycle genes in cardiomyocytes through its interaction with the cofactor SP2, providing a direct link between metabolism and proliferation at the gene transcriptional level. Our study reveals a key role of NFYa in regulating cardiac growth before birth and a previously unrecognized transcriptional control mechanism of metabolic genes in the heart, and highlights the importance of mitochondrial metabolism during fetal heart development and regeneration.
Project description:Cardiomyocytes are highly metabolic cells responsible for generating the contractile force that drives heart function. During fetal development and regeneration, these cells undergo active division but lose their proliferation activity in the adult heart. The mechanisms that coordinate their metabolism and proliferation are not fully understood. Here, we study the developmental functions of the transcription factor NFYa, which we previously identified from regenerating cardiomyocytes. We show that loss of NFYa profoundly alters cardiomyocyte composition, with a decrease in immature regenerative cells and an increase in trabecular and mature cardiomyocytes, as revealed by spatial and single-cell transcriptome analyses. NFYa-deleted cardiomyocytes exhibited reduced proliferation and impaired mitochondrial metabolism, contributing to the cardiac growth defect. NFYa acts as a transcriptional activator of mitochondrial metabolic genes as well as cell-cycle genes in cardiomyocytes through its interaction with the cofactor SP2, providing a direct link between metabolism and proliferation at the gene transcriptional level. Our study reveals a key role of NFYa in regulating cardiac growth before birth and a previously unrecognized transcriptional control mechanism of metabolic genes in the heart, and highlights the importance of mitochondrial metabolism during fetal heart development and regeneration.
Project description:Fetal lung samples at 12–20 post conception week (pcw) from the HDBR, up to 0.5cm3 in size, were embedded in OCT and flash-frozen in dry-ice cooled isopentane. Twelve-micron cryosections were cut onto Visium slides, haematoxylin and eosin stained and imaged at 20X magnification on a Hamamatsu Nanozoomer 2.0 HT Brightfield. These were then further processed according to the 10X Genomics Visium protocol, using a permeabilization time of 18 min for 12–17 pcw samples and 24 min for 19 pcw and older samples. Images were exported as tiled tiffs for analysis. Dual-indexed libraries were prepared as in the 10X Genomics protocol, pooled at 2.25 nM and sequenced in 4 samples per Illumina Novaseq SP flow cell with read lengths of 28 bp for R1, 10 bp for i7 index, 10 bp for i5 index, 90 bp for R2.
Project description:Fibroblasts are activated to repair the heart following injury. Fibroblast activation in the mammalian heart leads to a permanent fibrotic scar that impairs cardiac function. In other organisms, such as zebrafish, cardiac injury is followed by transient fibrosis and scar-free regeneration. The mechanisms that drive scarring versus scar-free regeneration are not well understood. Here, we show that the homeobox-containing transcription factor Prrx1b is required for scar-free regeneration of the zebrafish heart as the loss of Prrx1b results in excessive fibrosis and impaired cardiomyocyte proliferation. Through lineage tracing and single-cell RNA sequencing we find that Prrx1b is activated in epicardial-derived cells where it restricts TGFβ ligand expression and collagen production. Furthermore, through combined in vitro experiments in human fetal epicardial-derived cells and in vivo rescue experiments in zebrafish, we conclude that Prrx1 stimulates Nrg1 expression and promotes cardiomyocyte proliferation. Collectively, these results indicate that Prrx1 is a key transcription factor that balances fibrosis and regeneration in the injured zebrafish heart.
Project description:The neonatal mammalian heart is capable of substantial regeneration following injury through cardiomyocyte proliferation. However, this regenerative capacity is lost by postnatal (P) day 7. How to stimulate the adult cardiomyocyte to re-enter the cell cycle is still unknown. Accumulating evidence suggests that cardiomyocyte proliferation depends on its metabolic state. Due to the tight connection between the tricarboxylic acid cycle (TCA) and cell proliferation, we analyzed the TCA metabolites between P0.5 and P7 mouse hearts and found that α-ketoglutarate (α-KG) ranked first among the decreased metabolites. The intraperitoneal injection of exogenous α-KG extended the window of cardiomyocyte proliferation during heart development and promoted heart regeneration after myocardial infarction (MI) by inducing adult cardiomyocyte proliferation. This was confirmed in Ogdh-siRNA-treated mice with increased α-KG levels. Mechanistically, α-KG activates Jmjd3, a histone lysine demethylase, that decreases H3K27me3 expression and deposition of H3K4me3 at the promoters of cell cycle and structural maturation genes in cardiomyocytes. Our present study shows that α-KG promotes cardiomyocyte proliferation by Jmjd3-dependent demethylation and inactivation of H3K27me3 andH3K4me3, which is a potential therapeutic approach for treating MI and heart failure.