Joseph Wu, Postdoctoral Faculty Sponsor
Generation of two induced pluripotent stem cell lines from breast cancer patients carrying BRCA2 variants.
Stem cell research
2023; 72: 103219
Germline pathogenic variants in the BRCA2 gene are strongly correlated with an elevated risk of developing breast cancer. Two specific BRCA2 variants, c.8167G>C (p.Asp2723His) and c.1583del (p.Asn528fs), have been identified from individuals with a family history of breast cancer. Here we generated two iPSC lines from breast cancer patients who are heterozygous carriers of these two variants. These iPSCs exhibit pluripotency and demonstrate the capability to differentiate into three germ layers. These iPSC lines represent a valuable resource for personalized pre-clinical research, offering new opportunities to explore the underlying mechanisms of breast cancer and develop targeted therapeutic approaches.
View details for DOI 10.1016/j.scr.2023.103219
View details for PubMedID 37816281
Targeting CaMKII-delta 9 Ameliorates Cardiac Ischemia/Reperfusion Injury by Inhibiting Myocardial Inflammation
2022; 130 (6): 887-903
CaMKII (Ca2+/calmodulin-dependent kinase II) plays a central role in cardiac ischemia/reperfusion (I/R) injury-an important therapeutic target for ischemic heart disease. In the heart, CaMKII-δ is the predominant isoform and further alternatively spliced into 11 variants. In humans, CaMKII-δ9 and CaMKII-δ3, the major cardiac splice variants, inversely regulate cardiomyocyte viability with the former pro-death and the latter pro-survival. However, it is unknown whether specific inhibition of the detrimental CaMKII-δ9 prevents cardiac I/R injury and, if so, what is the underlying mechanism. Here, we aim to investigate the cardioprotective effect of specific CaMKII-δ9 inhibition against myocardial I/R damage and determine the underlying mechanisms.The role and mechanism of CaMKII-δ9 in cardiac I/R injury were investigated in mice in vivo, neonatal rat ventricular myocytes, and human embryonic stem cell-derived cardiomyocytes.We demonstrate that CaMKII-δ9 inhibition with knockdown or knockout of its feature exon, exon 16, protects the heart against I/R-elicited injury and subsequent heart failure. I/R-induced cardiac inflammation was also ameliorated by CaMKII-δ9 inhibition, and compared with the previously well-studied CaMKII-δ2, CaMKII-δ9 overexpression caused more profound cardiac inflammation. Mechanistically, in addition to IKKβ (inhibitor of NF-κB [nuclear factor-κB] kinase subunit β), CaMKII-δ9, but not δ2, directly interacted with IκBα (NF-κB inhibitor α) with its feature exon 13-16-17 combination and increased IκBα phosphorylation and consequently elicited more pronounced activation of NF-κB signaling and inflammatory response. Furthermore, the essential role of CaMKII-δ9 in myocardial inflammation and damage was confirmed in human cardiomyocytes.We not only identified CaMKII-δ9-IKK/IκB-NF-κB signaling as a new regulator of human cardiomyocyte inflammation but also demonstrated that specifically targeting CaMKII-δ9, the most abundant CaMKII-δ splice variant in human heart, markedly suppresses I/R-induced cardiac NF-κB activation, inflammation, and injury and subsequently ameliorates myocardial remodeling and heart failure, providing a novel therapeutic strategy for various ischemic heart diseases.
View details for DOI 10.1161/CIRCRESAHA.121.319478
View details for Web of Science ID 000769586100012
View details for PubMedID 35152717
CaMKII-delta9 Induces Cardiomyocyte Death to Promote Cardiomyopathy and Heart Failure.
Frontiers in cardiovascular medicine
2021; 8: 820416
Heart failure is a syndrome in which the heart cannot pump enough blood to meet the body's needs, resulting from impaired ventricular filling or ejection of blood. Heart failure is still a global public health problem and remains a substantial unmet medical need. Therefore, it is crucial to identify new therapeutic targets for heart failure. Ca2+/calmodulin-dependent kinase II (CaMKII) is a serine/threonine protein kinase that modulates various cardiac diseases. CaMKII-delta9 is the most abundant CaMKII-delta splice variant in the human heart and acts as a central mediator of DNA damage and cell death in cardiomyocytes. Here, we proved that CaMKII-delta9 mediated cardiomyocyte death promotes cardiomyopathy and heart failure. However, CaMKII-delta9 did not directly regulate cardiac hypertrophy. Furthermore, we also showed that CaMKII-delta9 induced cell death in adult cardiomyocytes through impairing the UBE2T/DNA repair signaling. Finally, we demonstrated no gender difference in the expression of CaMKII-delta9 in the hearts, together with its related cardiac pathology. These findings deepen our understanding of the role of CaMKII-delta9 in cardiac pathology and provide new insights into the mechanisms and therapy of heart failure.
View details for DOI 10.3389/fcvm.2021.820416
View details for PubMedID 35127874
CaMKII-delta 9 promotes cardiomyopathy through disrupting UBE2T-dependent DNA repair
NATURE CELL BIOLOGY
2019; 21 (9): 1152-+
Ca2+/calmodulin-dependent kinase II (CaMKII) is a multifunctional serine/threonine kinase family, and its δ isoform is predominant in the heart. Excessive CaMKII activation plays a pivotal role in the pathogenesis of severe heart conditions, including myocardial infarction, cardiomyopathy and heart failure. However, the identity of CaMKII splice variants and the mechanism(s) underlying CaMKII-mediated cardiac pathology remain elusive. Here, we show that CaMKII-δ9, the most abundant CaMKII-δ splice variant in human heart, potently promotes cardiomyocyte death, cardiomyopathy and heart failure by disrupting cardiomyocyte genome stability. Mechanistically, CaMKII-δ9, but not the previously well-studied CaMKII-δ2 and CaMKII-δ3, targets the ubiquitin-conjugating enzyme E2T (UBE2T) for phosphorylation and degradation, disrupting UBE2T-dependent DNA repair and leading to the accumulation of DNA damage and genome instability. These findings not only reveal a crucial role of CaMKII in the regulation of DNA repair, but also mark the CaMKII-δ9-UBE2T-DNA damage pathway as an important therapeutic target for cardiomyopathy and heart failure.
View details for DOI 10.1038/s41556-019-0380-8
View details for Web of Science ID 000484363700013
View details for PubMedID 31481791
CaMKII is a RIP3 substrate mediating ischemia- and oxidative stress-induced myocardial necroptosis
2016; 22 (2): 175-182
Regulated necrosis (necroptosis) and apoptosis are crucially involved in severe cardiac pathological conditions, including myocardial infarction, ischemia-reperfusion injury and heart failure. Whereas apoptotic signaling is well defined, the mechanisms that underlie cardiomyocyte necroptosis remain elusive. Here we show that receptor-interacting protein 3 (RIP3) triggers myocardial necroptosis, in addition to apoptosis and inflammation, through activation of Ca(2+)-calmodulin-dependent protein kinase (CaMKII) rather than through the well-established RIP3 partners RIP1 and MLKL. In mice, RIP3 deficiency or CaMKII inhibition ameliorates myocardial necroptosis and heart failure induced by ischemia-reperfusion or by doxorubicin treatment. RIP3-induced activation of CaMKII, via phosphorylation or oxidation or both, triggers opening of the mitochondrial permeability transition pore and myocardial necroptosis. These findings identify CaMKII as a new RIP3 substrate and delineate a RIP3-CaMKII-mPTP myocardial necroptosis pathway, a promising target for the treatment of ischemia- and oxidative stress-induced myocardial damage and heart failure.
View details for DOI 10.1038/nm.4017
View details for Web of Science ID 000369466800011
View details for PubMedID 26726877
Central role of E3 ubiquitin ligase MG53 in insulin resistance and metabolic disorders
2013; 494 (7437): 375-379
Insulin resistance is a fundamental pathogenic factor present in various metabolic disorders including obesity and type 2 diabetes. Although skeletal muscle accounts for 70-90% of insulin-stimulated glucose disposal, the mechanism underlying muscle insulin resistance is poorly understood. Here we show in mice that muscle-specific mitsugumin 53 (MG53; also called TRIM72) mediates the degradation of the insulin receptor and insulin receptor substrate 1 (IRS1), and when upregulated, causes metabolic syndrome featuring insulin resistance, obesity, hypertension and dyslipidaemia. MG53 expression is markedly elevated in models of insulin resistance, and MG53 overexpression suffices to trigger muscle insulin resistance and metabolic syndrome sequentially. Conversely, ablation of MG53 prevents diet-induced metabolic syndrome by preserving the insulin receptor, IRS1 and insulin signalling integrity. Mechanistically, MG53 acts as an E3 ligase targeting the insulin receptor and IRS1 for ubiquitin-dependent degradation, comprising a central mechanism controlling insulin signal strength in skeletal muscle. These findings define MG53 as a novel therapeutic target for treating metabolic disorders and associated cardiovascular complications.
View details for DOI 10.1038/nature11834
View details for Web of Science ID 000315312900043
View details for PubMedID 23354051
Computational protocol to identify shared transcriptional risks and mutually beneficial compounds between diseases.
2024; 5 (1): 102883
The accumulation of omics and biobank resources allows for a genome-wide understanding of the shared pathologic mechanisms between diseases and for strategies to identify drugs that could be repurposed as novel treatments. Here, we present a computational protocol, implemented as a Snakemake workflow, to identify shared transcriptional processes and screen compounds that could result in mutual benefit. This protocol also includes a description of a pharmacovigilance study designed to validate the effect of compounds using electronic health records. For complete details on the use and execution of this protocol, please refer to Gao et al.1 and Baylis et al.2.
View details for DOI 10.1016/j.xpro.2024.102883
View details for PubMedID 38354084
Generation and characterization of induced pluripotent stem cells from breast cancer patients carrying ATM mutations.
Stem cell research
2023; 73: 103246
We generated two induced pluripotent stem cell (iPSC) lines from peripheral blood mononuclear cells (PBMCs) of breast cancer patients carrying germline ATM mutations, a gene associated with a 7% prevalence in breast cancer. These iPSC lines displayed typical morphology, expressed pluripotency markers, maintained a stable karyotype, and retained the ability to differentiate into the three germ layers. These patient-specific iPSC lines hold great potential for mechanistic investigations and the development of drug screening strategies aimed at addressing ATM-related cancer.
View details for DOI 10.1016/j.scr.2023.103246
View details for PubMedID 37951143
- Editorial: Nutrition and metabolism in musculoskeletal disorders. Frontiers in nutrition 2023; 10: 1269939
Glycolytic reprogramming in macrophages and MSCs during inflammation.
Frontiers in immunology
2023; 14: 1199751
Dysregulated inflammation is associated with many skeletal diseases and disorders, such as osteolysis, non-union of fractures, osteonecrosis, osteoarthritis and orthopaedic infections. We previously showed that continuous infusion of lipopolysaccharide (LPS) contaminated polyethylene particles (cPE) caused prolonged inflammation and impaired bone formation. However, the metabolic and bioenergetic processes associated with inflammation of bone are unknown. Mitochondria are highly dynamic organelles that modulate cell metabolism and orchestrate the inflammatory responses that involve both resident and recruited cells. Glycolytic reprogramming, the shift from oxidative phosphorylation (OXPHOS) to glycolysis causes inappropriate cell activation and function, resulting in dysfunctional cellular metabolism. We hypothesized that impaired immunoregulation and bone regeneration from inflammatory states are associated with glycolytic reprogramming and mitochondrial dysfunction in macrophages (Mφ) and mesenchymal stromal cells (MSCs).We used the Seahorse XF96 analyzer and real-time qPCR to study the bioenergetics of Mφ and MSCs exposed to cPE. To understand the oxygen consumption rate (OCR), we used Seahorse XF Cell Mito Stress Test Kit with Seahorse XF96 analyzer. Similarly, Seahorse XF Glycolytic Rate Assay Kit was used to detect the extracellular acidification rate (ECAR) and Seahorse XF Real-Time ATP Rate Assay kit was used to detect the real-time ATP production rates from OXPHOS and glycolysis. Real-time qPCR was performed to analyze the gene expression of key enzymes in glycolysis and mitochondrial biogenesis. We further detected the gene expression of proinflammatory cytokines in Mφ and genes related to cell differentiation in MSC during the challenge of cPE.Our results demonstrated that the oxidative phosphorylation of Mφ exposed to cPE was significantly decreased when compared with the control group. We found reduced basal, maximal and ATP-production coupled respiration rates, and decreased proton leak in Mφ during challenge with cPE. Meanwhile, Mφ showed increased basal glycolysis and proton efflux rates (PER) when exposed to cPE. The percentage (%) of PER from glycolysis was higher in Mφ exposed to cPE, indicating that the contribution of the glycolytic pathway to total extracellular acidification was elevated during the challenge of cPE. In line with the results of OCR and ECAR, we found Mφ during cPE challenge showed higher glycolytic ATP (glycoATP) production rates and lower mitochondrial ATP (mitoATP) production rates which is mainly from OXPHOS. Interestingly, MSCs showed enhanced glycolysis during challenge with cPE, but no significant changes in oxygen consumption rates (OCR). In accordance, seahorse assay of real-time ATP revealed glycoATP rates were elevated while mitoATP rates showed no significant differences in MSC during challenge with cPE. Furthermore, Mφ and MSCs exposed to cPE showed upregulated gene expression levels of glycolytic regulators and Mφ exposed to cPE expressed higher levels of pro-inflammatory cytokines.This study demonstrated the dysfunctional bioenergetic activity of bone marrow-derived Mφ and MSCs exposed to cPE, which could impair the immunoregulatory properties of cells in the bone niche. The underlying molecular defect related to disordered mitochondrial function could represent a potential therapeutic target during the resolution of inflammation.
View details for DOI 10.3389/fimmu.2023.1199751
View details for PubMedID 37675119
View details for PubMedCentralID PMC10477714
Statins improve endothelial function via suppression of epigenetic-driven EndMT.
Nature cardiovascular research
2023; 2 (5): 467-485
The pleiotropic benefits of statins in cardiovascular diseases that are independent of their lipid-lowering effects have been well documented, but the underlying mechanisms remain elusive. Here we show that simvastatin significantly improves human induced pluripotent stem cell-derived endothelial cell functions in both baseline and diabetic conditions by reducing chromatin accessibility at transcriptional enhanced associate domain elements and ultimately at endothelial-to-mesenchymal transition (EndMT)-regulating genes in a yes-associated protein (YAP)-dependent manner. Inhibition of geranylgeranyltransferase (GGTase) I, a mevalonate pathway intermediate, repressed YAP nuclear translocation and YAP activity via RhoA signaling antagonism. We further identified a previously undescribed SOX9 enhancer downstream of statin-YAP signaling that promotes the EndMT process. Thus, inhibition of any component of the GGTase-RhoA-YAP-SRY box transcription factor 9 (SOX9) signaling axis was shown to rescue EndMT-associated endothelial dysfunction both in vitro and in vivo, especially under diabetic conditions. Overall, our study reveals an epigenetic modulatory role for simvastatin in repressing EndMT to confer protection against endothelial dysfunction.
View details for DOI 10.1038/s44161-023-00267-1
View details for PubMedID 37693816
View details for PubMedCentralID PMC10489108
Novel CaMKII-delta Inhibitor Hesperadin Exerts Dual Functions to Ameliorate Cardiac Ischemia/Reperfusion Injury and Inhibit Tumor Growth.
Background: Cardiac ischemia/reperfusion (I/R) injury has emerged as an important therapeutic target for ischemic heart disease, the leading cause of morbidity and mortality worldwide. Currently, there is no effective therapy for reducing cardiac I/R injury. Ca2+/calmodulin-dependent kinase II (CaMKII) plays a pivotal role in the pathogenesis of severe heart conditions, including I/R injury. Pharmacological inhibition of CaMKII is an important strategy in the protection against myocardial damage and cardiac diseases. To date, there is no drug targeting CaMKII for the clinical therapy of heart disease. Furthermore, currently, there is no selective inhibitor of CaMKII-delta, the major CaMKII isoform in the heart. Methods: A small-molecule kinase inhibitor library and a high-throughput screening system for the kinase activity assay of CaMKII-delta9 (the most abundant CaMKII-delta splice variant in human heart) were used to screen for CaMKII-delta inhibitors. Using cultured neonatal rat ventricular myocytes (NRVMs), human embryonic stem cell-derived cardiomyocytes, and in vivo mouse models, in conjunction with myocardial injury induced by I/R (or hypoxia/reoxygenation) and CaMKII-delta9 overexpression, we sought to investigate the protection of Hesperadin against cardiomyocyte death and cardiac diseases. BALB/c nude mice with xenografted tumors of human cancer cells were used to evaluate the in vivo anti-tumor effect of Hesperadin. Results: Based on the small-molecule kinase inhibitor library and screening system, we found that Hesperadin, an Aurora B kinase inhibitor with anti-tumor activity in vitro, directly bound to CaMKII-delta and specifically blocked its activation in an ATP-competitive manner. Functionally, Hesperadin ameliorated both I/R- and overexpressed CaMKII-delta9-induced cardiomyocyte death, myocardial damage, and heart failure in both rodents and human embryonic stem cell-derived cardiomyocytes. In addition, in an in vivo BALB/c nude mouse model with xenografted tumors of human cancer cells, Hesperadin delayed tumor growth without inducing cardiomyocyte death or cardiac injury. Conclusions: Here, we identified Hesperadin as a specific small-molecule inhibitor of CaMKII-delta with dual functions of cardioprotective and anti-tumor effects. These findings not only suggest that Hesperadin is a promising leading compound for clinical therapy of cardiac I/R injury and heart failure, but also provide a strategy for the joint therapy of cancer and cardiovascular disease caused by anticancer treatment.
View details for DOI 10.1161/CIRCULATIONAHA.121.055920
View details for PubMedID 35317609
Deconvoluting the Cells of the Human Heart with iPSC Technology: Cell Types, Protocols, and Uses.
Current cardiology reports
PURPOSE OF REVIEW: Induced pluripotent stem cells (iPSCs) have become widely adopted tools in cardiovascular biology due to their ability to differentiate into patient-specific cell types. Here, we describe the current protocols, important discoveries, and experimental limitations from the iPSC-derived cell types of the human heart: cardiomyocytes, cardiac fibroblasts, vascular smooth muscle cells, endothelial cells, and pericytes. In addition, we also examine the progress of 3D-based cell culture systems.RECENT FINDINGS: There has been rapid advancement in methods to generate cardiac iPSC-derived cell types. These advancements have led to improved cardiovascular disease modeling, elucidation of interactions among different cell types, and the creation of 3D-based cell culture systems able to provide more physiologically relevant insights into cardiovascular diseases. iPSCs have become an instrumental model system in the toolbox of cardiovascular biologists. Ongoing research continues to advance the use of iPSCs in (1) disease modeling, (2) drug screening, and (3) clinical trials in a dish.
View details for DOI 10.1007/s11886-022-01670-z
View details for PubMedID 35244869
Protocol to measure contraction, calcium, and action potential in human-induced pluripotent stem cell-derived cardiomyocytes.
2021; 2 (4): 100859
Multiple strategies have been developed to efficiently differentiate human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Here, we describe a protocol for measuring three key functional parameters of hiPSC-CMs, including contractile function, calcium (Ca2+) handling, and action potential. For complete details on the use and execution of this protocol, please refer to Zhang etal. (2021).
View details for DOI 10.1016/j.xpro.2021.100859
View details for PubMedID 34746854
The role of metabolism in directed differentiation versus trans-differentiation of cardiomyocytes.
Seminars in cell & developmental biology
The advent of induced pluripotent stem cells (iPSCs) and identification of transcription factors for cardiac reprogramming have raised hope to cure heart disease, the leading cause of death in the world. Our knowledge in heart development and molecular barriers of cardiac reprogramming is advancing, but many hurdles are yet to be overcome for clinical translation. Importantly, we lack a full understanding of molecular mechanisms governing cell fate conversion toward cardiomyocytes. In this review, we will discuss the role of metabolism in directed differentiation versus trans-differentiation of cardiomyocytes. Cardiomyocytes exhibit a unique metabolic feature distinct from PSCs and cardiac fibroblasts, and there are multiple overlapping molecular mechanisms underlying metabolic reprogramming during cardiomyogenesis. We will discuss key metabolic changes occurring during cardiomyocytes differentiation from PSCs and cardiac fibroblasts, and the potential role of metabolic reprogramming in the enhancement strategies for cardiomyogenesis. Only when such details are discovered will more effective strategies to enhance the de novo production of cardiomyocytes be possible.
View details for DOI 10.1016/j.semcdb.2021.05.018
View details for PubMedID 34074592
- Human Induced Pluripotent Stem Cells as a Screening Platform for Drug-Induced Vascular Toxicity FRONTIERS IN PHARMACOLOGY 2021; 12
Human Induced Pluripotent Stem Cells as a Screening Platform for Drug-Induced Vascular Toxicity.
Frontiers in pharmacology
2021; 12: 613837
Evaluation of potential vascular injury is an essential part of the safety study during pharmaceutical development. Vascular liability issues are important causes of drug termination during preclinical investigations. Currently, preclinical assessment of vascular toxicity primarily relies on the use of animal models. However, accumulating evidence indicates a significant discrepancy between animal toxicity and human toxicity, casting doubt on the clinical relevance of animal models for such safety studies. While the causes of this discrepancy are expected to be multifactorial, species differences are likely a key factor. Consequently, a human-based model is a desirable solution to this problem, which has been made possible by the advent of human induced pluripotent stem cells (iPSCs). In particular, recent advances in the field now allow the efficient generation of a variety of vascular cells (e.g., endothelial cells, smooth muscle cells, and pericytes) from iPSCs. Using these cells, different vascular models have been established, ranging from simple 2D cultures to highly sophisticated vascular organoids and microfluidic devices. Toxicity testing using these models can recapitulate key aspects of vascular pathology on molecular (e.g., secretion of proinflammatory cytokines), cellular (e.g., cell apoptosis), and in some cases, tissue (e.g., endothelium barrier dysfunction) levels. These encouraging data provide the rationale for continuing efforts in the exploration, optimization, and validation of the iPSC technology in vascular toxicology.
View details for DOI 10.3389/fphar.2021.613837
View details for PubMedID 33790786
View details for PubMedCentralID PMC8006367
Yixin-Shu Capsules Ameliorated Ischemia-Induced Heart Failure by Restoring Trx2 and Inhibiting JNK/p38 Activation
OXIDATIVE MEDICINE AND CELLULAR LONGEVITY
2021; 2021: 8049079
Traditional Chinese medicine has shown great safety and efficacy in the treatment of heart failure (HF), whereas the mechanism remains unclear. In this study, the protective effect of Yixin-shu (YXS) capsules, a conventional medicine for various cardiovascular diseases, against myocardial ischemia-induced HF in rats was systematically investigated by RNA-seq technology. HF rats treated with YXS (0.8 or 1.6 g/kg/d, ig) for 6 weeks had significantly decreased brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) and collagen III and attenuated cardiac structure rupture and collagen deposition. Additionally, YXS treatment decreased the levels of interleukin-1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and lactate dehydrogenase (LDH) and TUNEL-positive rate and the nitrotyrosine staining, but increased levels of glutathione (GSH), total antioxidant capacity (T-AOC) activity, and mitochondrial membrane potential. Further experiments demonstrated that YXS restored Trx2 and inhibited the phosphorylation of JNK and p38, thereby improving cardiac function in the rats with HF. Silencing Trx2 decreased the protection of YXS in the response to H2O2 as evidenced by the increase of caspase-3 activity and decrease of GSH level. Thus, YXS enhanced heart function and decreased myocardial damage through restoring Trx2 and inhibiting JNK and p38 activation in ischemia-induced HF.
View details for DOI 10.1155/2021/8049079
View details for Web of Science ID 000625294800001
View details for PubMedID 33643519
View details for PubMedCentralID PMC7902134
Cardiac Ischemic Preconditioning Promotes MG53 Secretion Through H2O2-Activated Protein Kinase C-delta Signaling
2020; 142 (11): 1077-1091
Ischemic heart disease is the leading cause of morbidity and mortality worldwide. Ischemic preconditioning (IPC) is the most powerful intrinsic protection against cardiac ischemia/reperfusion injury. Previous studies have shown that a multifunctional TRIM family protein, MG53 (mitsugumin 53; also called TRIM72), not only plays an essential role in IPC-mediated cardioprotection against ischemia/reperfusion injury but also ameliorates mechanical damage. In addition to its intracellular actions, as a myokine/cardiokine, MG53 can be secreted from the heart and skeletal muscle in response to metabolic stress. However, it is unknown whether IPC-mediated cardioprotection is causally related to MG53 secretion and, if so, what the underlying mechanism is.Using proteomic analysis in conjunction with genetic and pharmacological approaches, we examined MG53 secretion in response to IPC and explored the underlying mechanism using rodents in in vivo, isolated perfused hearts, and cultured neonatal rat ventricular cardiomyocytes. Moreover, using recombinant MG53 proteins, we investigated the potential biological function of secreted MG53 in the context of IPC and ischemia/reperfusion injury.We found that IPC triggered robust MG53 secretion in rodents in vivo, perfused hearts, and cultured cardiac myocytes without causing cell membrane leakage. Mechanistically, IPC promoted MG53 secretion through H2O2-evoked activation of protein kinase-C-δ. Specifically, IPC-induced myocardial MG53 secretion was mediated by H2O2-triggered phosphorylation of protein kinase-C-δ at Y311, which is necessary and sufficient to facilitate MG53 secretion. Functionally, systemic delivery of recombinant MG53 proteins to mimic elevated circulating MG53 not only restored IPC function in MG53-deficient mice but also protected rodent hearts from ischemia/reperfusion injury even in the absence of IPC. Moreover, oxidative stress by H2O2 augmented MG53 secretion, and MG53 knockdown exacerbated H2O2-induced cell injury in human embryonic stem cell-derived cardiomyocytes, despite relatively low basal expression of MG53 in human heart.We conclude that IPC and oxidative stress can trigger MG53 secretion from the heart via an H2O2-protein kinase-C-δ-dependent mechanism and that extracellular MG53 can participate in IPC protection against cardiac ischemia/reperfusion injury.
View details for DOI 10.1161/CIRCULATIONAHA.119.044998
View details for Web of Science ID 000573539100011
View details for PubMedID 32677469
Programmed necrosis in cardiomyocytes: mitochondria, death receptors and beyond
BRITISH JOURNAL OF PHARMACOLOGY
2019; 176 (22): 4319-4339
Excessive death of cardiac myocytes leads to many cardiac diseases, including myocardial infarction, arrhythmia, heart failure and sudden cardiac death. For the last several decades, most work on cell death has focused on apoptosis, which is generally considered as the only form of regulated cell death, whereas necrosis has been regarded to be an unregulated process. Recent findings reveal that necrosis also occurs in a regulated manner and that it is closely related to the physiology and pathophysiology of many organs, including the heart. The recognition of necrosis as a regulated process mandates a re-examination of cell death in the heart together with the mechanisms and therapy of cardiac diseases. In this study, we summarize the regulatory mechanisms of the programmed necrosis of cardiomyocytes, that is, the intrinsic (mitochondrial) and extrinsic (death receptor) pathways. Furthermore, the role of this programmed necrosis in various heart diseases is also delineated. Finally, we describe the currently known pharmacological inhibitors of several of the key regulatory molecules of regulated cell necrosis and the opportunities for their therapeutic use in cardiac disease. We intend to systemically summarize the recent progresses in the regulation and pathological significance of programmed cardiomyocyte necrosis along with its potential therapeutic applications to cardiac diseases. LINKED ARTICLES: This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.
View details for DOI 10.1111/bph.14363
View details for Web of Science ID 000500486100007
View details for PubMedID 29774530
View details for PubMedCentralID PMC6887687
beta-arrestin 2 mediates cardiac ischemia-reperfusion injury via inhibiting GPCR-independent cell survival signalling
2017; 113 (13): 1615-1626
Ischemic heart disease is a leading cause of morbidity and mortality worldwide. Although timely restoration of coronary blood flow (reperfusion) is the most effective therapeutics of myocardial infarction, reperfusion causes further cardiac damage, i.e. ischemia-reperfusion (I/R) injury. β-arrestins (Arrbs) have been traditionally defined as negative regulators of G protein-coupled receptor (GPCR) signalling, but recent studies have shown that they are essential for G protein-independent, GPCR-mediated biased signalling. Several ligands have been reported to be cardioprotective via Arrbs dependent pathway. However, it is unclear whether Arrbs exert receptor-independent physiological or pathological functions in the heart. Here, we sought to determine whether and how Arrbs play a role in regulating cardiomyocyte viability and myocardial remodelling following I/R injury.The expression of β-arrestin 2 (Arrb2), but not β-arrestin 1 (Arrb1), is upregulated in rat hearts subjected to I/R injury, or in cultured neonatal rat cardiomyocytes treated with hypoxia-reoxygenation (H/R) injury. Deficiency of Arrb2 in cultured neonatal rat cardiomyocytes alleviates H/R-induced cardiomyocyte death and Arrb2-/- mice are resistant to myocardial damage caused by I/R injury. In contrast, upregulation of Arrb2 triggers cardiomyocyte death and exaggerates I/R (or H/R)-induced detrimental effects. Mechanically, Arrb2 induces cardiomyocyte death by interacting with the p85 subunit of PI3K, and negatively regulating the formation of p85-PI3K/CaV3 survival complex, thus blocking activation of PI3K-Akt-GSK3β cell survival signalling pathway.We define an upregulation of Arrb2 as a pathogenic factor in cardiac I/R injury, and also reveal a novel GPCR-independent mechanism of Arrb2-mediated cell death signalling in the heart.
View details for DOI 10.1093/cvr/cvx147
View details for Web of Science ID 000413456100014
View details for PubMedID 29016703
Hominoid-Specific De Novo Protein-Coding Genes Originating from Long Non-Coding RNAs
2012; 8 (9): e1002942
Tinkering with pre-existing genes has long been known as a major way to create new genes. Recently, however, motherless protein-coding genes have been found to have emerged de novo from ancestral non-coding DNAs. How these genes originated is not well addressed to date. Here we identified 24 hominoid-specific de novo protein-coding genes with precise origination timing in vertebrate phylogeny. Strand-specific RNA-Seq analyses were performed in five rhesus macaque tissues (liver, prefrontal cortex, skeletal muscle, adipose, and testis), which were then integrated with public transcriptome data from human, chimpanzee, and rhesus macaque. On the basis of comparing the RNA expression profiles in the three species, we found that most of the hominoid-specific de novo protein-coding genes encoded polyadenylated non-coding RNAs in rhesus macaque or chimpanzee with a similar transcript structure and correlated tissue expression profile. According to the rule of parsimony, the majority of these hominoid-specific de novo protein-coding genes appear to have acquired a regulated transcript structure and expression profile before acquiring coding potential. Interestingly, although the expression profile was largely correlated, the coding genes in human often showed higher transcriptional abundance than their non-coding counterparts in rhesus macaque. The major findings we report in this manuscript are robust and insensitive to the parameters used in the identification and analysis of de novo genes. Our results suggest that at least a portion of long non-coding RNAs, especially those with active and regulated transcription, may serve as a birth pool for protein-coding genes, which are then further optimized at the transcriptional level.
View details for DOI 10.1371/journal.pgen.1002942
View details for Web of Science ID 000309817900020
View details for PubMedID 23028352
View details for PubMedCentralID PMC3441637