IGF2BP3 promotes adult myocardial regeneration by stabilizing MMP3 mRNA through interaction with m6A modification.

Myocardial infarction that causes damage to heart muscle can lead to heart failure. The identification of molecular mechanisms promoting myocardial regeneration represents a promising strategy to improve cardiac function. Here we show that IGF2BP3 plays an important role in regulating adult cardiomyocyte proliferation and regeneration in a mouse model of myocardial infarction. IGF2BP3 expression progressively decreases during postnatal development and becomes undetectable in the adult heart. However, it becomes upregulated after cardiac injury. Both gain- and loss-of-function analyses indicate that IGF2BP3 regulates cardiomyocyte proliferation in vitro and in vivo. In particular, IGF2BP3 promotes cardiac regeneration and improves cardiac function after myocardial infarction. Mechanistically, we demonstrate that IGF2BP3 binds to and stabilizes MMP3 mRNA through interaction with N6-methyladenosine modification. The expression of MMP3 protein is also progressively downregulated during postnatal development. Functional analyses indicate that MMP3 acts downstream of IGF2BP3 to regulate cardiomyocyte proliferation. These results suggest that IGF2BP3-mediated post-transcriptional regulation of extracellular matrix and tissue remodeling contributes to cardiomyocyte regeneration. They should help to define therapeutic strategy for ameliorating myocardial infarction by inducing cell proliferation and heart repair.

Propofol inhibits myocardial injury induced by microvesicles derived from hypoxia-reoxygenated endothelial cells via lncCCT4-2/CCT4 signaling.

BACKGROUND: Ischemia-reperfusion (IR) induces increased release of extracellular vesicles in the heart and exacerbates myocardial IR injury. We have previously shown that propofol attenuates hypoxia/reoxygenation (HR)-induced injury in human umbilical vein endothelial cells (HUVECs) and that microvesicles derived from propofol-treated HUVECs inhibit oxidative stress in endothelial cells. However, the role of microvesicles derived from propofol post-treated HUVECs ((HR + P)-EMVs) in IR-injured cardiomyocytes is unclear. In this study, we aimed to investigate the role of (HR + P)-EMVs in cardiac IR injury compared to microvesicles derived from hypoxic/reoxygenated HUVECs (HR-EMVs) and to elucidate the underlying mechanisms. METHODS: Hypoxia/reoxygenation (HR) models of HUVECs and AC16 cells and a mouse cardiac IR model were established. Microvesicles from HR-injured HUVECs, DMSO post-treated HUVECs and propofol post-treated HUVECs were extracted by ultra-high speed centrifugation, respectively. The above EMVs were co-cultured with HR-injured AC16 cells or injected intracardially into IR mice. Flow cytometry and immunofluorescence were used to determine the levels of oxidative stress and apoptosis in cardiomyocytes. Apoptosis related proteins were detected by Western blot. Echocardiography for cardiac function and Evans blue-TTC staining for myocardial infarct size. Expression of lncCCT4-2 in EMVs and AC16 cells was analysed by whole transcriptome sequencing of EMVs and RT-qPCR. The molecular mechanism of inhibition of myocardial injury by (HR + P)-EMVs was elucidated by lentiviral knockdown of lncCCT4-2, plasmid overexpression or knockdown of CCT4, and actinomycin D assay. RESULTS: In vitro and in vivo experiments confirmed that HR-EMVs exacerbated oxidative stress and apoptosis in IR-injured cardiomyocytes, leading to increased infarct size and worsened cardiac function. Notably, (HR + P)-EMVs induced significantly less oxidative stress and apoptosis in IR-injured cardiomyocytes compared to HR-EMVs. Mechanistically, RNA sequencing of EMVs and RT-qPCR showed that lncCCT4-2 was significantly upregulated in (HR + P)-EMVs and cardiomyocytes co-cultured with (HR + P)-EMVs. Reduction of lncCCT4-2 in (HR + P)-EMVs enhanced oxidative stress and apoptosis in IR-injured cardiomyocytes. Furthermore, the anti-apoptotic activity of lncCCT4-2 from (HR + P)-EMVs was achieved by increasing the stability of CCT4 mRNA and promoting the expression of CCT4 protein in cardiomyocytes. CONCLUSIONS: Our study showed that (HR + P)-EMVs uptake by IR-injured cardiomyocytes upregulated lncCCT4-2 in cardiomyocytes and promoted CCT4 expression, thereby inhibiting HR-EMVs induced oxidative stress and apoptosis.

Propofol inhibits myocardial injury induced by microvesicles derived from hypoxiareoxygenated endothelial cells via lncCCT4-2/CCT4 signaling

BACKGROUND: Ischemia-reperfusion (IR) induces increased release of extracellular vesicles in the heart and exacerbates myocardial IR injury. We have previously shown that propofol attenuates hypoxia/reoxygenation (HR)-induced injury in human umbilical vein endothelial cells (HUVECs) and that microvesicles derived from propofol-treated HUVECs inhibit oxidative stress in endothelial cells. However, the role of microvesicles derived from propofol post-treated HUVECs ((HR + P)-EMVs) in IR-injured cardiomyocytes is unclear. In this study, we aimed to investigate the role of (HR + P)-EMVs in cardiac IR injury compared to microvesicles derived from hypoxic/reoxygenated HUVECs (HR-EMVs) and to elucidate the underlying mechanisms. METHODS: Hypoxia/reoxygenation (HR) models of HUVECs and AC16 cells and a mouse cardiac IR model were established. Microvesicles from HR-injured HUVECs, DMSO post-treated HUVECs and propofol post-treated HUVECs were extracted by ultra-high speed centrifugation, respectively. The above EMVs were co-cultured with HR-injured AC16 cells or injected intracardially into IR mice. Flow cytometry and immunofluorescence were used to determine the levels of oxidative stress and apoptosis in cardiomyocytes. Apoptosis related proteins were detected by Western blot. Echocardiography for cardiac function and Evans blue-TTC staining for myocardial infarct size. Expression of lncCCT4-2 in EMVs and AC16 cells was analysed by whole transcriptome sequencing of EMVs and RT-qPCR. The molecular mechanism of inhibition of myocardial injury by (HR + P)-EMVs was elucidated by lentiviral knockdown of lncCCT4-2, plasmid overexpression or knockdown of CCT4, and actinomycin D assay. RESULTS: In vitro and in vivo experiments confirmed that HR-EMVs exacerbated oxidative stress and apoptosis in IR-injured cardiomyocytes, leading to increased infarct size and worsened cardiac function. Notably, (HR + P)-EMVs induced significantly less oxidative stress and apoptosis in IR-injured cardiomyocytes compared to HR-EMVs. Mechanistically, RNA sequencing of EMVs and RT-qPCR showed that lncCCT4-2 was significantly upregulated in (HR + P)-EMVs and cardiomyocytes co-cultured with (HR + P)-EMVs. Reduction of lncCCT4-2 in (HR + P)-EMVs enhanced oxidative stress and apoptosis in IR-injured cardiomyocytes. Furthermore, the anti-apoptotic activity of lncCCT4-2 from (HR + P)-EMVs was achieved by increasing the stability of CCT4 mRNA and promoting the expression of CCT4 protein in cardiomyocytes. CONCLUSIONS: Our study showed that (HR + P)-EMVs uptake by IR-injured cardiomyocytes upregulated lncCCT4-2 in cardiomyocytes and promoted CCT4 expression, thereby inhibiting HR-EMVs induced oxidative stress and apoptosis. Highlights Microvesicles from hypoxic/reoxygenated HUVECs (HR-EMVs) exacerbated oxidative stress and apoptosis in IR-injured cardiomyocytes. Microvesicles from propofol post-treated HUVECs ((HR + P)-EMVs) induced diminished oxidative stress and apoptosis in IR-injured cardiomyocytes compared with microvesicles from hypoxic/reoxygenated HUVECs (HR-EMVs). lncCCT4-2 was significantly highly expressed in (HR + P)-EMVs and cardiomyocytes co-cultured with (HR + P)-EMVs, and reduction of lncCCT4-2 in (HR + P)-EMVs enhanced oxidative stress and apoptosis in IR-injured cardiomyocytes. lncCCT4-2 inhibited HR-EMVs induced oxidative stress and apoptosis in HR-injured AC16 cells by increasing the stability of CCT4 mRNA and promoting the expression of CCT4 protein in AC16 cells.

N6-methyladenosine modulates long non-coding RNA in the developing mouse heart.

Long non-coding RNAs (lncRNAs) were reported to potentially play a regulatory role in the process of myocardial regeneration in the neonatal mouse. N6-methyladenosine (m6A) modification may play a key role in myocardial regeneration in mice and regulates a variety of biological processes through affecting the stability of lncRNAs. However, the map of m6A modification of lncRNAs in mouse cardiac development still remains unknown. We aimed to investigate the differences in the m6A status of lncRNAs during mouse cardiac development and reveal a potential role of m6A modification modulating lncRNAs in cardiac development and myocardial regeneration during cardiac development in mice. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) of the heart tissue in C57BL/6 J mice at postnatal day 1 (P1), P7 and P28 were performed to produce stagewise cardiac lncRNA m6A-methylomes in a parallel timeframe with the established loss of an intrinsic cardiac regeneration capacity and early postnatal development. There were significant differences in the distribution and abundance of m6A modifications in lncRNAs in the P7 vs P1 mice. In addition, the functional role of m6A in regulating lncRNA levels was established for selected transcripts with METTL3 silencing in neonatal cardiomyocytes in vitro. Based on our MeRIP-qPCR experiment data, both lncGm15328 and lncRNA Zfp597, that were not previously associated with cardiac regeneration, were found to be the most differently methylated at P1-P7. These two lncRNAs sponged several miRNAs which further regulated multiple mRNAs, including some of which have previously been linked with cardiac regeneration ability. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that differential m6A modifications were more enriched in functions and cellular signalling pathways related to cardiomyocyte proliferation. Our data suggested that the m6A modification on lncRNAs may play an important role in the regeneration of myocardium and cardiac development.

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

N6-Methyladenosine (m6A) plays important roles in regulating mRNA processing. Despite rapid progress in this field, little is known about the role and mechanism of m6A modification in myocardial development and cardiomyocyte regeneration. Existing studies have shown that the heart tissues of newborn mice have the capability of proliferation and regeneration, but its mechanism, particularly its relation to m6A methylation, remains unknown. Methods. To systematically profile the mRNA m6A modification pattern in the heart tissues of mice at different developmental stages, we jointly performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) of heart tissues of mice, respectively, aged 1 day old, 7 days old, and 28 days old. Results. We identified the linkages and association between differentially expressed mRNA transcripts and hyper or hypomethylated m6A peaks in C57BL/6J mice at different heart developmental stages. Results showed that the amount of m6A peaks and the level of m6A modification were the lowest in the heart of mice at 1 day old. By contrast, heart tissues from 7-day-old mice tended to possess the most m6A peaks and the highest global m6A level. However, the m6A characteristics of myocardial tissue changed little after 7 days old as compared to that of 1 day old. Specifically, we found 1269 downmethylated genes of 1434 methylated genes in 7-day-old mouse heart tissues as compared to those in 1-day-old mice. Hypermethylation of some specific genes may correlate with the heart's strong proliferative and regenerative capability at the first day after birth. In terms of m6A density, the tendency shifted from coding sequences (CDS) to 3'-untranslated regions (3'UTR) and stop codon with the progression of heart development. In addition, some genes demonstrated remarkable changes both in methylation and expression, like kiss1, plekha6, and megf6, which may play important roles in proliferation. Furthermore, signaling pathways highly related to proliferation such as "Wnt signaling pathway," "ECM-receptor interaction," and "cardiac chamber formation" were significantly enriched in 1-day-old methylated genes. Conclusions. Our results reveal a pattern that different m6A modifications are distributed in C57BL/6J heart tissue at different developmental stages, which provides new insights into a novel function of m6A methylation of mRNA in myocardial development and regeneration.

Propofol-induced MiR-20b expression initiates endogenous cellular signal changes mitigating hypoxia/re-oxygenation-induced endothelial autophagy in vitro.

Certain miRNAs can attenuate hypoxia/re-oxygenation-induced autophagic cell death reported in our previous studies, but how these miRNAs regulate the autophagy-related cellular signaling pathway in preventing cell death is largely unknown. In the current study, the autophagy-related miRNAs of hsa-miR-20b were investigated in an in vitro model of hypoxia/re-oxygenation-induced endothelial autophagic cell death. Of these, miR-20b was found to be the most important miRNA which targeted on the key autophagy kinase ULK1 and inhibited hypoxia/re-oxygenation injury-induced autophagy by decreasing both autophagosomes and LC3I to II transition rate and P62 degradation. These processes were reversed by the transfection of an miR-20b inhibitor. Re-expression of ULK1 restores miR-20b-inhibited autophagy. Propofol, a commonly used anesthetic, promoted miR-20b and METTL3 expression and attenuated endothelial autophagic cell death. The inhibited endogenous expression of miR-20b or silenced METTL3 diminished the protective effect of propofol and accentuated autophagy. Additionally, METTL3 knockdown significantly inhibited miR-20b expression but up-regulated pri-miR-20b expression. Together, our data shows that propofol protects against endothelial autophagic cell death induced by hypoxia/re-oxygenation injury, associated with activation of METTL3/miR-20b/ULK1 cellular signaling.