Ionizing radiation induces immediate protein acetylation changes in human cardiac microvascular endothelial cells

Coptisine prevents angiotensin II‑induced endothelial cell injury and senescence via the lncRNA SNHG12/miR‑603/NAMPT pathway

Atherosclerosis (AS) is a major health problem and targeting the associated molecular pathways is critical for developing therapies. The present study investigated the effect of coptisine on human umbilical vein endothelial cells (HUVECs) in response to angiotensin II (Ang II) induction by focusing on cellular senescence, apoptosis and inflammation. HUVECs were treated with different Ang II concentrations and long non-coding RNA small nucleolar RNA host gene 12 (SNHG12), microRNA (miRNA/miR)-603 and nicotinamide phosphoribosyltransferase (NAMPT) expressions were assessed. Cell viability, nicotinamide adenine dinucleotide (NAD+) levels, senescence, apoptosis and inflammation were assessed. The interactions among SNHG12, miR-603 and NAMPT were investigated using dual-luciferase reporter gene assays and RNA pull-down experiments. Coptisine treatment increased SNHG12 expression and attenuated Ang II-induced adverse effects in HUVECs. SNHG12 silencing abrogated coptisine's protective effects, indicating that SNHG12 is a key mediator. SNHG12 targets miR-603, which then directly targets NAMPT, an age-related gene involved in NAD(+) regulation. Coptisine modulated the SNHG12/miR-603/NAMPT pathway and miR-603 inhibition enhanced the protective effects of coptisine. NAMPT overexpression reversed the negative effects of miR-603 and enhanced the protective effect of the miR-603 inhibitor. Finally, the protective mechanism of coptisine is linked to the regulation of NAD(+), sirtuin 3 (SIRT3) and p53. Coptisine treatment counteracted the AngII-induced increase in SIRT3 and p53 protein levels, whereas the miR-603 inhibitor potentiated the effect of coptisine. SNHG12 knockdown partially abolished these effects, which were reversed by NAMPT overexpression. In conclusion, the present study revealed a novel protective mechanism involving the SNHG12/miR-603/NAMPT pathway in HUVECs exposed to Ang II, highlighting the potential therapeutic application of coptisine in treating atherosclerosis. These results suggested that coptisine exerts its protective effects by modulating the SNHG12/miR-603/NAMPT axis, which ultimately affects the regulation of NAD(+), SIRT3 and p53. Future studies should explore the potential of the SNHG12/miR-603/NAMPT pathway as a target for developing novel AS therapies.

New Insights into the Understanding of Mechanisms of Radiation-Induced Heart Disease

OPINION STATEMENT

Cancer patients who receive high-dose thoracic radiotherapy may develop radiation-induced heart disease (RIHD). The clinical presentation of RIHD comprises coronary artery atherosclerosis, valvular disease, pericarditis, cardiomyopathy, and conduction defects. These complications have significantly reduced due to the improved radiotherapy techniques. However, such methods still could not avoid heart radiation exposure. Furthermore, people who received relatively low-dose radiation exposures have exhibited significantly elevated RIHD risks in cohort studies of atomic bomb survivors and occupational exposures. The increased potential in exposure to natural and artificial ionizing radiation sources has emphasized the necessity to understand the development of RIHD. The pathological processes of RIHD include endothelial dysfunction, inflammation, fibrosis, and hypertrophy. The underlying mechanisms may involve the changes in oxidative stress, DNA damage response, telomere erosion, mitochondrial dysfunction, epigenetic regulation, circulation factors, protein post-translational modification, and metabolites. This review will discuss the recent advances in the mechanisms of RIHD at cellular and molecular levels.

MG149 Inhibits MOF-Mediated p53 Acetylation to Attenuate X-Ray Radiation-Induced Apoptosis in H9c2 Cells

Cardiomyocyte apoptosis is involved in the pathogenesis of radiation-induced heart disease, but the underlying epigenetic mechanism remains elusive. We evaluated the potential mediating role of males absent on the first (MOF) in the association between epigenetic activation of p53 lysine 120 (p53K120) and X-ray radiation-induced apoptosis in H9c2 cells. H9c2 cells were pretreated for 24 h with the MOF inhibitor MG149 after 4 Gy irradiation, followed by assessment of cell proliferation, injury, and apoptosis. MOF expression was upregulated by X-ray radiation. MG149 suppressed the proliferation inhibition, reduction of mitochondrial membrane potential, ROS production, and cell apoptosis. MG149 may promote the survival of H9c2 cells via inhibition of MOF-mediated p53K120 acetylation in response to X-ray radiation-induced apoptosis. Our data indicates a MOF-associated epigenetic mechanism in H9c2 cells that promotes attenuation of X-ray radiation-induced injury.

Application of radiation omics in the development of adverse outcome pathway networks: an example of radiation-induced cardiovascular disease

BACKGROUND

Epidemiological studies have indicated that exposure of the heart to doses of ionizing radiation as low as 0.5 Gy increases the risk of cardiac morbidity and mortality with a latency period of decades. The damaging effects of radiation to myocardial and endothelial structures and functions have been confirmed radiobiologically at high dose, but much less is known at low dose. Integration of radiation biology and epidemiology data is a recommended approach to improve the radiation risk assessment process. The adverse outcome pathway (AOP) framework offers a comprehensive tool to compile and translate mechanistic information into pathological endpoints which may be relevant for risk assessment at the different levels of a biological system. Omics technologies enable the generation of large volumes of biological data at various levels of complexity, from molecular pathways to functional organisms. Given the quality and quantity of available data across levels of biology, omics data can be attractive sources of information for use within the AOP framework. It is anticipated that radiation omics studies could improve our understanding of the molecular mechanisms behind the adverse effects of radiation on the cardiovascular system. In this review, we explored the available omics studies on radiation-induced cardiovascular disease (CVD) and their applicability to the proposed AOP for CVD.

RESULTS

The results of 80 omics studies published on radiation-induced CVD over the past 20 years have been discussed in the context of the AOP of CVD proposed by Chauhan et al. Most of the available omics data on radiation-induced CVD are from proteomics, transcriptomics, and metabolomics, whereas few datasets were available from epigenomics and multi-omics. The omics data presented here show great promise in providing information for several key events of the proposed AOP of CVD, particularly oxidative stress, alterations of energy metabolism, extracellular matrix and vascular remodeling.

CONCLUSIONS

The omics data presented here shows promise to inform the various levels of the proposed AOP of CVD. However, the data highlight the urgent need of designing omics studies to address the knowledge gap concerning different radiation scenarios, time after exposure and experimental models. This review presents the evidence to build a qualitative omics-informed AOP and provides views on the potential benefits and challenges in using omics data to assess risk-related outcomes.

The highs and lows of ionizing radiation and its effects on protein synthesis

Ionizing radiation (IR) is a constant feature of our environment and one that can dramatically affect organismal health and development. Although the impacts of high-doses of IR on mammalian cells and systems have been broadly explored, there are still challenges in accurately quantifying biological responses to IR, especially in the low-dose range to which most individuals are exposed in their lifetime. The resulting uncertainty has led to the entrenchment of conservative radioprotection policies around the world. Thus, uncovering long-sought molecular mechanisms and tissue responses that are targeted by IR could lead to more informed policymaking and propose new therapeutic avenues for a variety of pathologies. One often overlooked target of IR is mRNA translation, a highly regulated cellular process that consumes more than 40% of the cell's energy. In response to environmental stimuli, regulation of mRNA translation allows for precise and rapid changes to the cellular proteome, and unsurprisingly high-dose of IR was shown to trigger a severe reprogramming of global protein synthesis allowing the cell to conserve energy by preventing the synthesis of unneeded proteins. Nonetheless, under these conditions, certain mRNAs encoding specific proteins are translationally favoured to produce the factors essential to repair the cell or send it down the path of no return through programmed cell death. Understanding the mechanisms controlling protein synthesis in response to varying doses of IR could provide novel insights into how this stress-mediated cellular adaptation is regulated and potentially uncover novel targets for radiosensitization or radioprotection. Here, we review the current literature on the effects of IR at both high- and low-dose on the mRNA translation machinery.

Protective Effect of Sirt1 against Radiation-Induced Damage

Radiotherapy is an important method for the treatment of malignant tumors. It can directly or indirectly lead to the formation of free radicals and DNA damage, resulting in a series of biological effects, including tumor cell death and normal tissue damage. These radiation effects are typically accompanied by the abnormal expression of sirtuin 1 (Sirt1), which deacetylates histones and non-histones. These Sirt1 substrates, including transcription factors and some catalytic enzymes, play a crucial role in anti-oxidative stress, DNA damage repair, autophagy regulation, anti-senescence, and apoptosis, which are closely related to triggering cell defense and survival in radiation-induced damage. In this article, we review the mechanisms underlying cellular responses to ionizing radiation and the role of Sirt1 in the process, with the aim of providing a theoretical basis for protection against radiation by Sirt1 as well as novel targets for developing radioprotective agents.

Twenty years of proteomics in radiation biology - a look back

PURPOSE

The aim of this article is to describe the technical development in proteomics during the last two decades with the focus on its use in radiation biology. It is written from a subjective point of view and aims not to be a scientific review of the subject.

CONCLUSION

Proteomics is a fast developing technique and it has already contributed greatly to our understanding of biological mechanisms following radiation exposure. Novel proteomics approaches can be used in adequately designed cellular and animal experiments and above all in big clinical trials to investigate effects of ionizing radiation in the future.

Resveratrol attenuates radiation enteritis through the SIRT1/FOXO3a and PI3K/AKT signaling pathways

Radiation enteritis (RE) is the most common radiotherapy complication, and effective RE treatments are lacking. Resveratrol exerts beneficial effects on radiation injury. However, the effect of resveratrol in radiation-induced intestinal injury and the underlying mechanism remain unclear. Here, a C57BL/6 mouse model of RE was established and an intestinal epithelial cell line was used to evaluate the protective effects of resveratrol against radiation-induced intestinal injury and the underlying mechanisms. Resveratrol improved radiation-induced oxidative stress and cell apoptosis via upregulating antioxidant enzymes and downregulating p53 acetylation. In vivo, resveratrol-treated mice exhibited longer survival; longer villi; more intestinal crypt cells; upregulated expression of Ki67, catalase, and superoxide dismutase 2; and fewer inflammatory proteins and apoptotic cells. These protective effects were suppressed by inhibition of SIRT1. These results demonstrate that resveratrol can reduce radiation-induced intestinal injury by inhibiting oxidative stress and apoptosis via the SIRT1/FOXO3a and PI3K/AKT pathways.

Radiobiological Studies of Microvascular Damage through In Vitro Models: A Methodological Perspective

Ionizing radiation (IR) is used in radiotherapy as a treatment to destroy cancer. Such treatment also affects other tissues, resulting in the so-called normal tissue complications. Endothelial cells (ECs) composing the microvasculature have essential roles in the microenvironment's homeostasis (ME). Thus, detrimental effects induced by irradiation on ECs can influence both the tumor and healthy tissue. In-vitro models can be advantageous to study these phenomena. In this systematic review, we analyzed in-vitro models of ECs subjected to IR. We highlighted the critical issues involved in the production, irradiation, and analysis of such radiobiological in-vitro models to study microvascular endothelial cells damage. For each step, we analyzed common methodologies and critical points required to obtain a reliable model. We identified the generation of a 3D environment for model production and the inclusion of heterogeneous cell populations for a reliable ME recapitulation. Additionally, we highlighted how essential information on the irradiation scheme, crucial to correlate better observed in vitro effects to the clinical scenario, are often neglected in the analyzed studies, limiting the translation of achieved results.

Tumor Suppressor Protein p53 and Inhibitor of Apoptosis Proteins in Colorectal Cancer-A Promising Signaling Network for Therapeutic Interventions

Simple Summary

Tumor suppressor 53 (p53) is a multifunctional protein that regulates cell cycle, DNA repair, apoptosis and metabolic pathways. In colorectal cancer (CRC), mutations of the gene occur in 60% of patients and are associated with a more aggressive tumor phenotype and resistance to anti-cancer therapy. In addition, inhibitor of apoptosis (IAP) proteins are distinguished biomarkers overexpressed in CRC that impact on a diverse set of signaling pathways associated with the regulation of apoptosis/autophagy, cell migration, cell cycle and DNA damage response. As these mechanisms are further firmly controlled by p53, a transcriptional and post-translational regulation of IAPs by p53 is expected to occur in cancer cells. Here, we aim to review the molecular regulatory mechanisms between IAPs and p53 and discuss the therapeutic potential of targeting their interrelationship by multimodal treatment options.

Abstract

Despite recent advances in the treatment of colorectal cancer (CRC), patient’s individual response and clinical follow-up vary considerably with tumor intrinsic factors to contribute to an enhanced malignancy and therapy resistance. Among these markers, upregulation of members of the inhibitor of apoptosis protein (IAP) family effects on tumorigenesis and radiation- and chemo-resistance by multiple pathways, covering a hampered induction of apoptosis/autophagy, regulation of cell cycle progression and DNA damage response. These mechanisms are tightly controlled by the tumor suppressor p53 and thus transcriptional and post-translational regulation of IAPs by p53 is expected to occur in malignant cells. By this, cellular IAP1/2, X-linked IAP, Survivin, BRUCE and LIVIN expression/activity, as well as their intracellular localization is controlled by p53 in a direct or indirect manner via modulating a multitude of mechanisms. These cover, among others, transcriptional repression and the signal transducer and activator of transcription (STAT)3 pathway. In addition, p53 mutations contribute to deregulated IAP expression and resistance to therapy. This review aims at highlighting the mechanistic and clinical importance of IAP regulation by p53 in CRC and describing potential therapeutic strategies based on this interrelationship.

Acute total body ionizing gamma radiation induces long-term adverse effects and immediate changes in cardiac protein oxidative carbonylation in the rat

Radiation-induced heart disease presents a significant challenge in the event of an accidental radiation exposure as well as to cancer patients who receive acute doses of irradiation as part of radiation therapy. We utilized the spontaneously hypertensive Wistar-Kyoto rat model, previously shown to demonstrate drug-induced cardiomyopathy, to evaluate the acute and long-term effects of sub-lethal total body gamma irradiation at two, four, and fifty-two weeks. We further examined irreversible oxidative protein carbonylation in the heart immediately following irradiation in the normotensive Wistar-Kyoto rat. Both males and females sustained weight loss and anemic conditions compared to untreated controls over a one-year period as reflected by reduced body weight and low red blood cell count. Increased inflammation was detected by elevated IL-6 serum levels selectively in males at four weeks. Serum cardiac troponin T and I analyses revealed signs of cardiomyopathy at earlier timepoints, but high variability was observed, especially at one year. Echocardiography at two weeks following 5.0Gy treatment revealed a significant decrease in cardiac output in females and a significant decrease in both diastolic and systolic volumes in males. Following 10.0Gy irradiation in the normotensive Wistar-Kyoto rat, the heart tissue showed an increase in total protein oxidative carbonylation accompanied by DNA damage indicated by an increase in γ-H2AX. Using proteomic analyses, we identified several novel proteins which showed a marked difference in carbonylation including those of mitochondrial origin and most notably, cardiac troponin T, one of the key proteins involved in cardiomyocyte contractility. Overall, we present findings of acute oxidative protein damage, DNA damage, cardiac troponin T carbonylation, and long-term cardiomyopathy in the irradiated animals.

Hyperacetylation of Cardiac Mitochondrial Proteins Is Associated with Metabolic Impairment and Sirtuin Downregulation after Chronic Total Body Irradiation of ApoE -/- Mice

Chronic exposure to low-dose ionizing radiation is associated with an increased risk of cardiovascular disease. Alteration in energy metabolism has been suggested to contribute to radiation-induced heart pathology, mitochondrial dysfunction being a hallmark of this disease. The goal of this study was to investigate the regulatory role of acetylation in heart mitochondria in the long-term response to chronic radiation. ApoE-deficient C57Bl/6J mice were exposed to low-dose-rate (20 mGy/day) gamma radiation for 300 days, resulting in a cumulative total body dose of 6.0 Gy. Heart mitochondria were isolated and analyzed using quantitative proteomics. Radiation-induced proteome and acetylome alterations were further validated using immunoblotting, enzyme activity assays, and ELISA. In total, 71 proteins showed peptides with a changed acetylation status following irradiation. The great majority (94%) of the hyperacetylated proteins were involved in the TCA cycle, fatty acid oxidation, oxidative stress response and sirtuin pathway. The elevated acetylation patterns coincided with reduced activity of mitochondrial sirtuins, increased the level of Acetyl-CoA, and were accompanied by inactivation of major cardiac metabolic regulators PGC-1 alpha and PPAR alpha. These observations suggest that the changes in mitochondrial acetylation after irradiation is associated with impairment of heart metabolism. We propose a novel mechanism involved in the development of late cardiac damage following chronic irradiation.

Analysis of a lectin microarray identifies altered sialylation of mouse serum glycoproteins induced by whole-body radiation exposure

Microarrays containing 45 different lectins were analyzed to identify global changes in the glycosylation of serum glycoproteins from mice exposed to whole-body γ-radiation. The results showed that radiation exposure increased and decreased the relative amounts of α-2,3- and α-2,6-sialic acids, respectively. The expression of α-2,3- and α-2,6-sialyltransferase genes in the liver was analyzed to determine whether changes in their expression were responsible for the sialic acid changes. The increase in α-2,3-sialic acid correlated with St3gal5 upregulation after radiation exposure; however, a decrease in St6gal1 expression was not observed. Analysis of a PCR array of genes expressed in irradiated mouse livers revealed that irradiation did not alter the expression of most of the included genes. These results suggest that glycomic screening of serum glycoproteins using lectin microarrays can be a powerful tool for identifying radiation-induced changes in the post-translational addition of sugar moieties to proteins. In addition, the results indicate that altered sialylation of glycoproteins may be an initial response to acute radiation exposure.

Proteomics landscape of radiation-induced cardiovascular disease: somewhere over the paradigm

INTRODUCTION

Epidemiological studies clearly show that thoracic or whole body exposure to ionizing radiation increases the risk of cardiac morbidity and mortality. Radiation-induced cardiovascular disease (CVD) has been intensively studied during the last ten years but the underlying molecular mechanisms are still poorly understood. Areas covered: Heart proteomics is a powerful tool holding promise for the future research. The central focus of this review is to compare proteomics data on radiation-induced CVD with data arising from proteomics of healthy and diseased cardiac tissue in general. In this context we highlight common and unique features of radiation-related and other heart pathologies. Future prospects and challenges of the field are discussed. Expert commentary: Data from comprehensive cardiac proteomics have deepened the knowledge of molecular mechanisms involved in radiation-induced cardiac dysfunction. State-of-the-art proteomics has the potential to identify novel diagnostic and therapeutic markers of this disease.

Cardiovascular diseases related to ionizing radiation: The risk of low-dose exposure (Review)

Traditionally, non-cancer diseases are not considered as health risks following exposure to low doses of ionizing radiation. Indeed, non-cancer diseases are classified as deterministic tissue reactions, which are characterized by a threshold dose. It is judged that below an absorbed dose of 100 mGy, no clinically relevant tissue damage occurs, forming the basis for the current radiation protection system concerning non-cancer effects. Recent epidemiological findings point, however, to an excess risk of non-cancer diseases following exposure to lower doses of ionizing radiation than was previously thought. The evidence is the most sound for cardiovascular disease (CVD) and cataract. Due to limited statistical power, the dose-risk relationship is undetermined below 0.5 Gy; however, if this relationship proves to be without a threshold, it may have considerable impact on current low-dose health risk estimates. In this review, we describe the CVD risk related to low doses of ionizing radiation, the clinical manifestation and the pathology of radiation-induced CVD, as well as the importance of the endothelium models in CVD research as a way forward to complement the epidemiological data with the underlying biological and molecular mechanisms.

Modulation of the cytoplasmic functions of mammalian post-transcriptional regulatory proteins by methylation and acetylation: a key layer of regulation waiting to be uncovered?

Post-transcriptional control of gene expression is critical for normal cellular function and viability and many of the proteins that mediate post-transcriptional control are themselves subject to regulation by post-translational modification (PTM), e.g. phosphorylation. However, proteome-wide studies are revealing new complexities in the PTM status of mammalian proteins, in particular large numbers of novel methylated and acetylated residues are being identified. Here we review studied examples of methylation/acetylation-dependent regulation of post-transcriptional regulatory protein (PTRP) function and present collated PTM data that points to the huge potential for regulation of mRNA fate by these PTMs.

Dynamic Protein Acetylation in Plant-Pathogen Interactions

Pathogen infection triggers complex molecular perturbations within host cells that results in either resistance or susceptibility. Protein acetylation is an emerging biochemical modification that appears to play central roles during host-pathogen interactions. To date, research in this area has focused on two main themes linking protein acetylation to plant immune signaling. Firstly, it has been established that proper gene expression during defense responses requires modulation of histone acetylation within target gene promoter regions. Second, some pathogens can deliver effector molecules that encode acetyltransferases directly within the host cell to modify acetylation of specific host proteins. Collectively these findings suggest that the acetylation level for a range of host proteins may be modulated to alter the outcome of pathogen infection. This review will focus on summarizing our current understanding of the roles of protein acetylation in plant defense and highlight the utility of proteomics approaches to uncover the complete repertoire of acetylation changes triggered by pathogen infection.