Zinc supplementation prevents cardiomyocyte apoptosis and congenital heart defects in embryos of diabetic mice

Atractylenolide-I Alleviates Hyperglycemia-Induced Heart Developmental Malformations through Direct and Indirect Modulation of the STAT3 Pathway

BACKGROUND

Gestational diabetes could elevate the risk of congenital heart defects (CHD) in infants, and effective preventive and therapeutic medications are currently lacking. Atractylenolide-I (AT-I) is the active ingredient of Atractylodes Macrocephala Koidz (known as Baizhu in China), which is a traditional pregnancy-supporting Chinese herb.

PURPOSE

In this study, we investigated the protective effect of AT-I on the development of CHD in embryos exposed to high glucose (HG).

STUDY DESIGN AND METHODS

First, systematic review search results revealed associations between gestational diabetes mellitus (GDM) and cardiovascular malformations. Subsequently, a second systematic review indicated that heart malformations were consistently associated with oxidative stress and cell apoptosis. We assessed the cytotoxic impacts of Atractylenolide compounds (AT-I, AT-II, and AT-III) on H9c2 cells and chick embryos, determining an optimal concentration of AT-I for further investigation. Second, immunofluorescence, western blot, Polymerase Chain Reaction (PCR), and flow cytometry were utilized to delve into the mechanisms through which AT-I mitigates oxidative stress and apoptosis in cardiac cells. Molecular docking was employed to investigate whether AT-I exerts cardioprotective effects via the STAT3 pathway. Then, we developed a streptozotocin-induced diabetes mellitus (PGDM) mouse model to evaluate AT-I's protective efficacy in mammals. Finally, we explored how AT-I protects hyperglycemia-induced abnormal fetal heart development through microbiota analysis and untargeted metabolomics analysis.

RESULTS

The study showed the protective effect of AT-I on embryonic development using a chick embryo model which rescued the increase in the reactive oxygen species (ROS) and decrease in cell survival induced by HG. We also provided evidence suggesting that AT-I might directly interact with STAT3, inhibiting its phosphorylation. Further, in the PGDM mouse model, we observed that AT-I not only partially alleviated PGDM-related blood glucose issues and complications but also mitigated hyperglycemia-induced abnormal fetal heart development in pregnant mice. This effect is hypothesized to be mediated through alterations in gut microbiota composition. We proposed that dysregulation in microbiota metabolism could influence the downstream STAT3 signaling pathway via EGFR, consequently impacting cardiac development and formation.

CONCLUSIONS

This study marks the first documented instance of AT-I's effectiveness in reducing the risk of early cardiac developmental anomalies in fetuses affected by gestational diabetes. AT-I achieves this by inhibiting the STAT3 pathway activated by ROS during gestational diabetes, significantly reducing the risk of fetal cardiac abnormalities. Notably, AT-I also indirectly safeguards normal fetal cardiac development by influencing the maternal gut microbiota and suppressing the EGFR/STAT3 pathway.

Embryonic diapause due to high glucose is related to changes in glycolysis and oxidative phosphorylation, as well as abnormalities in the TCA cycle and amino acid metabolism

Introduction

The adverse effects of high glucose on embryos can be traced to the preimplantation stage. This study aimed to observe the effect of high glucose on early-stage embryos.

Methods and results

Seven-week-old ICR female mice were superovulated and mated, and the zygotes were collected. The zygotes were randomly cultured in 5 different glucose concentrations (control, 20mM, 40mM, 60mM and 80mM glucose). The cleavage rate, blastocyst rate and total cell number of blastocyst were used to assess the embryo quality. 40 mM glucose was selected to model high glucose levels in this study. 40mM glucose arrested early embryonic development, and the blastocyst rate and total cell number of the blastocyst decreased significantly as glucose concentration was increased. The reduction in the total cell number of blastocysts in the high glucose group was attributed to decreased proliferation and increased cell apoptosis, which is associated with the diminished expression of GLUTs (GLUT1, GLUT2, GLUT3). Furthermore, the metabolic characterization of blastocyst culture was observed in the high-glucose environment.

Discussion

The balance of glycolysis and oxidative phosphorylation at the blastocyst stage was disrupted. And embryo development arrest due to high glucose is associated with changes in glycolysis and oxidative phosphorylation, as well as abnormalities in the TCA cycle and amino acid metabolism.

Maternal Pre-Existing Diabetes: A Non-Inherited Risk Factor for Congenital Cardiopathies

Congenital heart defects (CHDs) are the most common form of birth defects in humans. They occur in 9 out of 1000 live births and are defined as structural abnormalities of the heart. Understanding CHDs is difficult due to the heterogeneity of the disease and its multifactorial etiology. Advances in genomic sequencing have made it possible to identify the genetic factors involved in CHDs. However, genetic origins have only been found in a minority of CHD cases, suggesting the contribution of non-inherited (environmental) risk factors to the etiology of CHDs. Maternal pregestational diabetes is associated with a three- to five-fold increased risk of congenital cardiopathies, but the underlying molecular mechanisms are incompletely understood. According to current hypotheses, hyperglycemia is the main teratogenic agent in diabetic pregnancies. It is thought to induce cell damage, directly through genetic and epigenetic dysregulations and/or indirectly through production of reactive oxygen species (ROS). The purpose of this review is to summarize key findings on the molecular mechanisms altered in cardiac development during exposure to hyperglycemic conditions in utero. It also presents the various in vivo and in vitro techniques used to experimentally model pregestational diabetes. Finally, new approaches are suggested to broaden our understanding of the subject and develop new prevention strategies.

Novel hub genes and regulatory network related to ferroptosis in tetralogy of Fallot

Ferroptosis is a newly discovered type of cell death mainly triggered by uncontrolled lipid peroxidation, and it could potentially have a significant impact on the development and progression of tetralogy of Fallot (TOF). Our project aims to identify and validate potential genes related to ferroptosis in TOF. We obtained sequencing data of TOF from the GEO database and ferroptosis-related genes from the ferroptosis database. We employed bioinformatics methods to analyze the differentially expressed mRNAs (DEmRNAs) and microRNAs between the normal control group and TOF group and identify DEmRNAs related to ferroptosis. Protein-protein interaction analysis was conducted to screen hub genes. Furthermore, a miRNA-mRNA-TF co-regulatory network was constructed to utilize prediction software. The expression of hub genes was further validated through quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). After conducting the differential gene analysis, we observed that in TOF, 41 upregulated mRNAs and three downregulated mRNAs associated with ferroptosis genes were found. Further Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analysis revealed that these genes were primarily involved in molecular functions and biological processes related to chemical stress, oxidative stress, cellular response to starvation, response to nutrient levels, cellular response to external stimulus, and cellular response to extracellular stimulus. Furthermore, we constructed a miRNA-mRNA-TF co-regulatory network. qRT-PCR analysis of the right ventricular tissues from human cases showed an upregulation in the mRNA levels of KEAP1 and SQSTM1. Our bioinformatics analysis successfully identified 44 potential genes that are associated with ferroptosis in TOF. This finding significantly contributes to our understanding of the molecular mechanisms underlying the development of TOF. Moreover, these findings have the potential to open new avenues for the development of innovative therapeutic approaches for the treatment of this condition.

Charting the Path: Navigating Embryonic Development to Potentially Safeguard against Congenital Heart Defects

Congenital heart diseases (CHDs) are structural or functional defects present at birth due to improper heart development. Current therapeutic approaches to treating severe CHDs are primarily palliative surgical interventions during the peri- or prenatal stages, when the heart has fully developed from faulty embryogenesis. However, earlier interventions during embryonic development have the potential for better outcomes, as demonstrated by fetal cardiac interventions performed in utero, which have shown improved neonatal and prenatal survival rates, as well as reduced lifelong morbidity. Extensive research on heart development has identified key steps, cellular players, and the intricate network of signaling pathways and transcription factors governing cardiogenesis. Additionally, some reports have indicated that certain adverse genetic and environmental conditions leading to heart malformations and embryonic death may be amendable through the activation of alternative mechanisms. This review first highlights key molecular and cellular processes involved in heart development. Subsequently, it explores the potential for future therapeutic strategies, targeting early embryonic stages, to prevent CHDs, through the delivery of biomolecules or exosomes to compensate for faulty cardiogenic mechanisms. Implementing such non-surgical interventions during early gestation may offer a prophylactic approach toward reducing the occurrence and severity of CHDs.

Research Progress of Maternal Metabolism on Cardiac Development and Function in Offspring

The developmental origin of health and disease (DOHaD) hypothesis refers to the adverse effects of suboptimal developmental environments during embryonic and early fetal stages on the long-term health of offspring. Intrauterine metabolic perturbations can profoundly impact organogenesis in offspring, particularly affecting cardiac development and giving rise to potential structural and functional abnormalities. In this discussion, we contemplate the existing understanding regarding the impact of maternal metabolic disorders, such as obesity, diabetes, or undernutrition, on the developmental and functional aspects of the offspring's heart. This influence has the potential to contribute to the susceptibility of offspring to cardiovascular health issues. Alteration in the nutritional milieu can influence mitochondrial function in the developing hearts of offspring, while also serving as signaling molecules that directly modulate gene expression. Moreover, metabolic disorders can exert influence on cardiac development-related genes epigenetically through DNA methylation, levels of histone modifications, microRNA expression, and other factors. However, the comprehensive understanding of the mechanistic underpinnings of these phenomena remains incomplete. Further investigations in this domain hold profound clinical significance, as they can contribute to the enhancement of public health and the prevention of cardiovascular diseases.

ER stress and lipid imbalance drive embryonic cardiomyopathy in a human heart organoid model of pregestational diabetes

Congenital heart defects constitute the most common birth defect in humans, affecting approximately 1% of all live births. The incidence of congenital heart defects is exacerbated by maternal conditions, such as diabetes during the first trimester. Our ability to mechanistically understand these disorders is severely limited by the lack of human models and the inaccessibility to human tissue at relevant stages. Here, we used an advanced human heart organoid model that recapitulates complex aspects of heart development during the first trimester to model the effects of pregestational diabetes in the human embryonic heart. We observed that heart organoids in diabetic conditions develop pathophysiological hallmarks like those previously reported in mouse and human studies, including ROS-mediated stress and cardiomyocyte hypertrophy, among others. Single cell RNA-seq revealed cardiac cell type specific-dysfunction affecting epicardial and cardiomyocyte populations, and suggested alterations in endoplasmic reticulum function and very long chain fatty acid lipid metabolism. Confocal imaging and LC-MS lipidomics confirmed our observations and showed that dyslipidemia was mediated by fatty acid desaturase 2 (FADS2) mRNA decay dependent on IRE1-RIDD signaling. We also found that the effects of pregestational diabetes could be reversed to a significant extent using drug interventions targeting either IRE1 or restoring healthy lipid levels within organoids, opening the door to new preventative and therapeutic strategies in humans.

Exposure to essential and non-essential trace elements and risks of congenital heart defects: A narrative review

Congenital heart defects (CHDs) are congenital abnormalities involving the gross structures of the heart and large blood vessels. Environmental factors, genetic factors and their interactions may contribute to the pathogenesis of CHDs. Generally, trace elements can be classified into essential trace elements and non-essential trace elements. Essential trace elements such as copper (Cu), zinc (Zn), iron (Fe), selenium (Se), and manganese (Mn) play important roles in human biological functions such as metabolic function, oxidative stress regulation, and embryonic development. Non-essential trace elements such as cadmium (Cd), arsenic (As), lead (Pb), nickle (Ni), barium (Ba), chromium (Cr) and mercury (Hg) are harmful to health even at low concentrations. Recent studies have revealed the potential involvement of these trace elements in the pathogenesis of CHDs. In this review, we summarized current studies exploring exposure to essential and non-essential trace elements and risks of CHDs, in order to provide further insights for the pathogenesis and prevention of CHDs.

The Epidemiology and Mechanisms of Lifetime Cardiopulmonary Morbidities Associated With Pre-Pregnancy Obesity and Excessive Gestational Weight Gain

Obesity has reached pandemic proportions in the last few decades. The global increase in obesity has contributed to an increase in the number of pregnant women with pre-pregnancy obesity or with excessive gestational weight gain. Obesity during pregnancy is associated with higher incidence of maternal co-morbidities such as gestational diabetes and hypertension. Both obesity during pregnancy and its associated complications are not only associated with immediate adverse outcomes for the mother and their newborns during the perinatal period but, more importantly, are linked with long-term morbidities in the offsprings. Neonates born to women with obesity are at higher risk for cardiac complications including cardiac malformations, and non-structural cardiac issues such as changes in the microvasculature, e.g., elevated systolic blood pressure, and overt systemic hypertension. Pulmonary diseases associated with maternal obesity include respiratory distress syndrome, asthma during childhood and adolescence, and adulthood diseases, such as chronic obstructive pulmonary disease. Sequelae of short-term complications compound long-term outcomes such as long-term obesity, hypertension later in life, and metabolic complications including insulin resistance and dyslipidemia. Multiple mechanisms have been proposed to explain these adverse outcomes and are related to the emerging knowledge of pathophysiology of obesity in adults. The best investigated ones include the role of obesity-mediated metabolic alterations and systemic inflammation. There is emerging evidence linking metabolic and immune derangements to altered biome, and alteration in epigenetics as one of the intermediary mechanisms underlying the adverse outcomes. These are initiated as part of fetal adaptation to obesity during pregnancy which are compounded by rapid weight gain during infancy and early childhood, a known complication of obesity during pregnancy. This newer evidence points toward the role of specific nutrients and changes in biome that may potentially modify the adverse outcomes observed in the offsprings of women with obesity.

Maternal Zinc, Copper, and Selenium Intakes during Pregnancy and Congenital Heart Defects

The effects of zinc, copper, and selenium on human congenital heart defects (CHDs) remain unclear. This study aimed to investigate the associations of the maternal total, dietary, and supplemental intakes of zinc, copper, and selenium during pregnancy with CHDs. A hospital-based case-control study was performed, including 474 cases and 948 controls in Northwest China. Eligible participants waiting for delivery were interviewed to report their diets and characteristics in pregnancy. Mixed logistic regression was adopted to examine associations and interactions between maternal intakes and CHDs. Higher total intakes of zinc, selenium, zinc to copper ratio, and selenium to copper ratio during pregnancy were associated with lower risks of total CHDs and the subtypes, and the tests for trend were significant (all p < 0.05). The significantly inverse associations with CHDs were also observed for dietary intakes of zinc, selenium, zinc to copper ratio, selenium to copper ratio, and zinc and selenium supplements use during pregnancy and in the first trimester. Moreover, high zinc and high selenium, even with low or high copper, showed a significantly reduced risk of total CHDs. Efforts to promote zinc and selenium intakes during pregnancy need to be strengthened to reduce the incidence of CHDs in the Chinese population.

miR-153-3p Targets βII Spectrin to Regulate Formaldehyde-Induced Cardiomyocyte Apoptosis

Background: Formaldehyde (FA) is ubiquitous in the environment and can be transferred to the fetus through placental circulation, causing miscarriage and congenital heart disease (CHD). Studies have shown that βII spectrin is necessary for cardiomyocyte survival and differentiation, and its loss leads to heart development defects and cardiomyocyte apoptosis. Additionally, previous studies have demonstrated that miRNA is essential in heart development and remodeling. However, whether miRNA regulates FA-induced CHD and cardiomyocyte apoptosis remains unclear. Methods: Using commercially available rat embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis. Real-time quantitative PCR (RT-qPCR) and Western blot were performed to examine the level of miR-153-3p, βII spectrin, caspase 7, cleaved caspase7, Bax, Bcl-2 expression in embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis. Apoptotic cell populations were evaluated by flow cytometry and Tunel. Luciferase activity assay and RNA pull-down assay were used to detect the interaction between miR-153-3p and βII spectrin. Masson's trichrome staining detects the degree of tissue fibrosis. Fluorescence in situ hybridization (FISH) and Immunohistochemistry were used to detect the expression of miR-153-3p and βII spectrin in tissues. Results: Using commercially available rat embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis, our studies indicate that miR-153-3p plays a regulatory role by directly targeting βII spectrin to promote cardiomyocyte apoptosis. miR-153-3p mainly regulates cardiomyocyte apoptosis by regulating the expression of caspase7, further elucidating the importance of apoptosis in heart development. Finally, the results with our animal model revealed that targeting the miR-153-3p/βII spectrin pathway effectively regulated FA-induced damage during heart development. Recovery experiments with miR-153-3p antagomir resulted in the reversal of FA-induced cardiomyocyte apoptosis and fetal cardiac fibrosis. Conclusion: This study investigated the molecular mechanism underpinning the role of βII spectrin in FA-induced CHD and the associated upstream miRNA pathway. The study findings suggest that miR-153-3p may provide a potential target for the clinical diagnosis and treatment of CHD.

Impact of maternal hyperglycemia on cardiac development: Insights from animal models

Congenital heart disease (CHD) is the leading cause of birth defect-related death in infants and is a global pediatric health concern. While the genetic causes of CHD have become increasingly recognized with advances in genome sequencing technologies, the etiology for the majority of cases of CHD is unknown. The maternal environment during embryogenesis has a profound impact on cardiac development, and numerous environmental factors are associated with an elevated risk of CHD. Maternal diabetes mellitus (matDM) is associated with up to a fivefold increased risk of having an infant with CHD. The rising prevalence of diabetes mellitus has led to a growing interest in the use of experimental diabetic models to elucidate mechanisms underlying this associated risk for CHD. The purpose of this review is to provide a comprehensive summary of rodent models that are being used to investigate alterations in cardiac developmental pathways when exposed to a maternal diabetic setting and to summarize the key findings from these models. The majority of studies in the field have utilized the chemically induced model of matDM, but recent advances have also been made using diet based and genetic models. Each model provides an opportunity to investigate unique aspects of matDM and is invaluable for a comprehensive understanding of the molecular and cellular mechanisms underlying matDM-associated CHD.

Maternal obesity and metabolic disorders associate with congenital heart defects in the offspring: A systematic review

BACKGROUND

Congenital heart defects (CHDs) are the most common congenital malformations. The aetiology of CHDs is complex. Large cohort studies and systematic reviews and meta-analyses based on these have reported an association between higher risk of CHDs in the offspring and individual maternal metabolic disorders such as obesity, diabetes, hypertension, and preeclampsia, all conditions that can be related to insulin resistance or hyperglycaemia. However, the clinical reality is that these conditions often occur simultaneously. The aim of this review is, in consequence, both to evaluate the existing evidence on the association between maternal metabolic disorders, defined as obesity, diabetes, hypertension, preeclampsia, dyslipidaemia and CHDs in the offspring, as well as the significance of combinations, such as metabolic syndrome, as risk factors.

METHODS

A systematic literature search of papers published between January 1, 1990 and January 14, 2021 was conducted using PubMed and Embase. Studies were eligible if they were published in English and were case-control or cohort studies. The exposures of interest were maternal overweight or obesity, hypertension, preeclampsia, diabetes, dyslipidaemia, and/or metabolic syndrome, and the outcome of interest was CHDs in the offspring. Furthermore, the studies were included according to a quality assessment score.

RESULTS

Of the 2,250 identified studies, 32 qualified for inclusion. All but one study investigated only the individual metabolic disorders. Some disorders (obesity, gestational diabetes, and hypertension) increased risk of CHDs marginally whereas pre-gestational diabetes and early-onset preeclampsia were strongly associated with CHDs, without consistent differences between CHD subtypes. A single study suggested a possible additive effect of maternal obesity and gestational diabetes.

CONCLUSIONS

Future studies of the role of aberrations of the glucose-insulin homeostasis in the common aetiology and mechanisms of metabolic disorders, present during pregnancy, and their association, both as single conditions and-particularly-in combination, with CHDs are needed.

Streptozotocin (STZ)-Induced Diabetes Affects Tissue Trace Element Content in Rats in a Dose-Dependent Manner

The objective of the present study was investigation of tissue trace element distribution in a streptozotocin model of DM1 in rats. DM1 was modeled in 2-month-old male Wistar rats (n = 30) using intraperitoneal injection of 45 mg/kg b.w. (STZ1) and 55 mg/kg b.w. streptozotocin (STZ2), whereas control animals were injected with physiological saline. The rats were subjected to oral glucose tolerance test (OGTT) and HbA1c level assessment at day 14. At day 30, blood serum, liver, kidney, and heart samples were collected for tissue trace element assessment using inductively coupled plasma mass spectrometry (ICP-MS). STZ-treated rats were characterized by lack of significant weight gain and elevated HbA1c and blood glucose levels. ICP-MS analysis demonstrated a dose-dependent accumulation of Cu, Mn, Mo, and Se levels in the liver. Correspondingly, the dose-dependent increase in renal Cu, Mn, V, and Zn levels was significant, whereas the observed trend for kidney V and Mo accumulation was nearly significant. The patterns of trace element content in the myocardium of STZ-exposed rats were quite different from those observed for liver and kidney. Only cardiac Zn content was characterized by a significant decrease. Serum Co, Cr, Cu, Se, V, and Mo levels were characterized by a significant decrease in response to STZ-induced diabetes. Generally, the obtained data demonstrate that diabetes is associated with altered copper, manganese, molybdenum, chromium, and vanadium handling. In turn, only altered Zn status may provide a link to diabetic cardiotoxicity. However, the particular mechanisms of both impaired metal handling in STZ diabetes and their potential anti-diabetic activity require further investigation.

Zinc oxide nanoparticles modulate the gene expression of ZnT1 and ZIP8 to manipulate zinc homeostasis and stress-induced cytotoxicity in human neuroblastoma SH-SY5Y cells

Zinc ions (Zn²⁺) are important messenger molecules involved in various physiological functions. To maintain the homeostasis of cytosolic Zn²⁺ concentration ([Zn²⁺]_c), Zrt/Irt-related proteins (ZIPs) and Zn²⁺ transporters (ZnTs) are the two families of proteins responsible for decreasing and increasing the [Zn²⁺]_c, respectively, by fluxing Zn²⁺ across the membranes of the cell and intracellular compartments in opposite directions. Most studies focus on the cytotoxicity incurred by a high concentration of [Zn²⁺]_c and less investigate the [Zn²⁺]_c at physiological levels. Zinc oxide-nanoparticle (ZnO-NP) is blood brain barrier-permeable and elevates the [Zn²⁺]_c to different levels according to the concentrations of ZnO-NP applied. In this study, we mildly elevated the [Zn²⁺]_c by ZnO-NP at concentrations below 1 μg/ml, which had little cytotoxicity, in cultured human neuroblastoma SH-SY5Y cells and characterized the importance of Zn²⁺ transporters in 6-hydroxy dopamine (6-OHDA)-induced cell death. The results show that ZnO-NP at low concentrations elevated the [Zn²⁺]_c transiently in 6 hr, then declined gradually to a basal level in 24 hr. Knocking down the expression levels of ZnT₁ (located mostly at the plasma membrane) and ZIP₈ (present in endosomes and lysosomes) increased and decreased the ZnO-NP-induced elevation of [Zn²⁺]_c, respectively. ZnO-NP treatment reduced the basal levels of reactive oxygen species and Bax/Bcl-2 mRNA ratios; in addition, ZnO-NP decreased the 6-OHDA-induced ROS production, p53 expression, and cell death. These results show that ZnO-NP-induced mild elevation in [Zn²⁺]_c activates beneficial effects in reducing the 6-OHDA-induced cytotoxic effects. Therefore, brain-delivery of ZnO-NP can be regarded as a potential therapy for neurodegenerative diseases.

Maternal Obesity and Diabetes Mellitus as Risk Factors for Congenital Heart Disease in the Offspring

Congenital heart disease (CHD) is the most common anatomical malformation occurring live‐born infants and an increasing cause of morbidity and mortality across the lifespan and throughout the world. Population‐based observations have long described associations between maternal cardiometabolic disorders and the risk of CHD in the offspring. Here we review the epidemiological evidence and clinical observations relating maternal obesity and diabetes mellitus to the risk of CHD offspring with particular attention to mechanistic models of maternal‐fetal risk transmission and first trimester disturbances of fetal cardiac development. A deeper understanding of maternal risk factors holds the potential to improve both prenatal detection of CHD by identifying at‐risk pregnancies, along with primary prevention of disease by improving preconception and prenatal treatment of at‐risk mothers.

Zinc ameliorates human aortic valve calcification through GPR39 mediated ERK1/2 signalling pathway

AIMS

Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. It has been reported that zinc is accumulated in calcified human aortic valves. However, whether zinc directly regulates CAVD is yet to be elucidated. The present study sought to determine the potential role of zinc in the pathogenesis of CAVD.

METHODS AND RESULTS

Using a combination of a human valve interstitial cell (hVIC) calcification model, human aortic valve tissues, and blood samples, we report that 20 μM zinc supplementation attenuates hVIC in vitro calcification, and that this is mediated through inhibition of apoptosis and osteogenic differentiation via the zinc-sensing receptor GPR39-dependent ERK1/2 signalling pathway. Furthermore, we report that GPR39 protein expression is dramatically reduced in calcified human aortic valves, and there is a significant reduction in zinc serum levels in patients with CAVD. Moreover, we reveal that 20 μM zinc treatment prevents the reduction of GPR39 observed in calcified hVICs. We also show that the zinc transporter ZIP13 and ZIP14 are significantly increased in hVICs in response to zinc treatment. Knockdown of ZIP13 or ZIP14 significantly inhibited hVIC in vitro calcification and osteogenic differentiation.

CONCLUSIONS

Together, these findings suggest that zinc is a novel inhibitor of CAVD, and report that zinc transporter ZIP13 and ZIP14 are important regulators of hVIC in vitro calcification and osteogenic differentiation. Zinc supplementation may offer a potential therapeutic strategy for CAVD.

The Functional Analysis of Selenium-Related Genes and Magnesium-Related Genes in the Gene Expression Profile Microarray in the Peripheral Blood Mononuclear Cells of Keshan Disease

Keshan disease (KD) is an endemic cardiomyopathy with high mortality. Selenium (Se) deficiency is closely related to KD, while magnesium (Mg) plays many critical roles in the cardiovascular function. The molecular mechanism of KD pathogenesis is still unclear. Until now, we have not found any studies investigating the association between Se- or Mg-related genes and KD. In this study, oligonucleotide microarray analysis was used to identify the differentially expressed genes in the peripheral blood mononuclear cells between KD patients and normal controls. Next, human metabolome database (HMDB) was used to screen Se- and Mg-related genes. Function classification, gene pathway, and interaction network of Se- and Mg-related genes in KD peripheral blood mononuclear cells were defined by FunRich (functional enrichment analysis tool). Among 83 differentially expressed genes, five Se-related (DIO2, GPX1, GPX2, GPX4, and GPX7) and five Mg-related (ACSL6, EYA4, IDH2, PPM1A, and STK11) genes were recognized from HMDB. Two significant biological processes (energy pathways and metabolism), one molecular function (peroxidase activity), one biological pathway (glutathione redox reactions I), and one gene interaction network were constituted from Se-related and Mg-related genes. Se-related gene DIO2 and Mg-related genes STK11 and IDH2 may have key roles in the myocardial dysfunction of KD. However, we still have not obtained any interaction between Se-related gene and Mg-related gene. The interactions between RPS6KB1, PTEN, ATM, HSP90AA1, SNRK, PRKAA2, SMARCA4, HSPA1A, and STK11 may play important roles in the abnormal cardiac function of KD.

Effect of Exogenous Zinc on MsrB1 Expression and Protein Oxidation in Human Lens Epithelial Cells

Aging has been related to zinc deficiency, resulting in protein oxidation and age-related decline of methionine sulfoxide reductase (Msr) activity. This study was designed to investigate the levels of methionine sulfoxide reductase B1 (MsrB1) mRNA and oxidized proteins in human lens epithelial (hLE) cells after treatment with exogenous zinc. The role of exogenous zinc in regulation of MsrB1 gene expression and protein oxidation in hLE cells was studied by MTT assay, oxidized protein measurement kit, and real-time PCR. The results showed that hLE cell viability was significantly decreased by MsrB1 gene knockdown or peroxynitrite (ONOO^-) treatment, while it was significantly increased after treatment with exogenous zinc (P < 0.05). Protein carbonyl content in hLE cell by MsrB1 gene knockdown or ONOO^- treatment was significantly decreased after treatment with ZnSO₄ (P < 0.01). And exogenous zinc could increase the level of MsrB1 in hLE cell under normal (P < 0.001) and oxidative stress (P < 0.01) conditions. In conclusion, exogenous zinc could protect hLE cells against MsrB1 gene knockdown or ONOO^--induced cell death by upregulation of MsrB1 involved in the elimination of reactive oxygen species (ROS) and oxidized proteins.

Emerging Biomarkers in Cutaneous Melanoma

Earlier identification of aggressive melanoma remains a goal in the field of melanoma research. With new targeted and immune therapies that have revolutionized the care of patients with melanoma, the ability to predict progression and monitor or predict response to therapy has become the new focus of research into biomarkers in melanoma. In this review, promising biomarkers are highlighted. These biomarkers have been used to diagnose melanoma as well as predict progression to advanced disease and response to therapy. The biomarkers take various forms, including protein expression at the level of tissue, genetic mutations of cancer cells, and detection of circulating DNA. First, a brief description is provided about the conventional tissue markers used to stage melanoma, including tumor depth. Next, protein biomarkers, which provide both diagnostic and prognostic information, are described. This is followed by a discussion of important genetic mutations, microRNA, and epigenetic modifications that can provide therapeutic and prognostic material. Finally, emerging serologic biomarkers are reviewed, including circulating melanoma cells and exosomes. Overall the goal is to identify biomarkers that aid in the earlier identification and improved treatment of aggressive melanoma.

Evidence of Zinc in Affording Protection Against X-Ray-Induced Brain Injury in Rats

In the present world, X-rays have been regarded as one of the most efficient tools in medicine, industry and research. On the contrary, extensive human exposure to these rays is responsible for causing detrimental effects on physiological system. The aim of the present study was to investigate the role of zinc (Zn), if any, in mitigating the adverse effects induced by fractionated X-irradiation on rat brain. Female Sprague-Dawley rats weighing 170-200 g were divided into four different groups viz.: (a) normal control, (b) X-irradiated (21Gy), (c) zinc treated (227 mg/L in drinking water) and (d) X-irradiated + zinc treated. The skulls of animals belonging to groups (b) and (d) were exposed to X-rays in 30 fractions. Each fraction delivered a radiation dose of 70 rads, and rats were exposed to two fractions every day for 15 days, consecutively. X-ray treatment resulted in significant alterations in the neurobehavior, neurotransmitter levels and neuro-histoarchitecture of rats, whereas zinc co-treatment with X-rays resulted in significant improvement in these parameters. X-ray exposure also caused a significant increase in the levels of lipid peroxidation as well as activities of catalase and superoxide dismutase, which however were decreased upon simultaneous Zn treatment. On the contrary, X-ray treatment down-regulated the glutathione system, which were found to be up-regulated by zinc co-treatment. Further, protein expressions of p53 and NF-ҚB were found to be significantly elevated after X-irradiation, which were reversed following Zn supplementation. Hence, Zn seems to be an effective agent in mitigating the detrimental effects caused by exposure to X-rays.

Effects of Chronic and Acute Zinc Supplementation on Myocardial Ischemia-Reperfusion Injury in Rats

The present study aims to explore the effects of chronic and acute zinc sulfate supplementation on myocardial ischemia-reperfusion injury in rats. The study registered 50 adult male rats which were divided into five groups in equal numbers as follows: group 1, normal control; group 2, sham; group 3, myocardial ischemia reperfusion (My/IR): the group which was fed on a normal diet and in which myocardial I/R was induced; group 4, myocardial ischemia reperfusion + chronic zinc: (5 mg/kg i.p. zinc sulfate for 15 days); and group 5, myocardial ischemia reperfusion + acute zinc: the group which was administered 15 mg/kg i.p. zinc sulfate an hour before the operation and in which myocardial I/R was induced. The collected blood and cardiac tissue samples were analyzed using spectrophotometric method to determine levels of MDA, as an indicator of tissue injury, and GSH, as an indicator of antioxidant activity. The highest plasma and heart tissue MDA levels were measured in group 3 (p < 0.05). Group 5 had lower MDA values than group 3, while group 4 had significantly lower MDA values than groups 3 and 5 (p < 0.05). The highest erythrocyte GSH values were found in group 4 (p < 0.05). Erythrocyte GSH values in group 5 were higher than those in group 3 (p < 0.05). The highest GSH values in heart tissue were measured in group 4 (p < 0.05). The results of the study reveal that the antioxidant activity inhibited by elevated oxidative stress in heart ischemia reperfusion in rats is restored partially by acute zinc administration and markedly by chronic zinc supplementation.

Comparative study of cardio-protective effects of zinc oxide nanoparticles and zinc sulfate in streptozotocin-induced diabetic rats

The cardio-protective effects of zinc oxide nanoparticles (Zn NPs) against diabetes-induced cardiopathy were evaluated and compared with zinc sulfate (ZnSO₄). A total of 120 Wistar rats were randomly categorized as healthy and diabetic groups. Then, the 2 groups were classified in 5 subgroups. The animals received oral supplementations containing different Zn NP (ie, doses of 1, 3, and 10mg/kg) and ZnSO₄ (30mg/kg) concentrations over 8 weeks. Blood and cardiac tissue samples were collected in the different time intervals and subjected to biochemical and histopathological analysis. Zn NPs showed dual effects, as its middle dose played protective role and recovered cardiac damages evidenced by significant reduction of serum cholesterol, HDL-cholesterol, lipoprotein (a), atherogenic index, TNF-α, cardiac MDA, B-type natriuretic peptide and caspase-3 activity. Apoptosis indices and histopathological features also were improved. However, the highest dose was found to be toxic and resulted in aggravation of the injuries. Another interesting finding is the ability of the higher doses of Zn-NPs (3 and 10mg/kg) to elevate cardiac zinc levels above the normal range in healthy animal. ZnSO₄ also helped to recuperation of the damages, but the middle dose of Zn NPs was more efficient as compared to ZnSO₄. Conclusively, Zn NPs have the potential for Zn delivery in diabetic patients.

Regulation of Na+-K+-ATPase effected high glucose-induced myocardial cell injury through c-Src dependent NADPH oxidase/ROS pathway

Depressed Na⁺/K⁺-ATPase activity has long been reported to be involved in diabetic-related cardiomyocyte death and cardiac dysfunction. However, the nature of directly regulating Na⁺-K⁺-ATPase in diabetic-related myocardial diseases remains unknown. Hyperglycemia is believed as one of major factors responsible for diabetic-related myocardial apoptosis and dysfunction. In this study, whether inhibiting Na⁺-K⁺-ATPase by ouabain or activating Na⁺-K⁺-ATPase by DRm217 has functions on high glucose (HG) -induced myocardial injury was investigated. Here we found that addition of DRm217 or ouabain to HG-treated cells had opposite effects. DRm217 decreased but ouabain increased HG-induced cell injury and apoptosis. This was mediated by changing Na⁺-K⁺-ATPase activity and Na⁺-K⁺-ATPase cell surface expression. The inhibition of Na⁺-K⁺-ATPase endocytosis alleviated HG-induced ROS accumulation. Na⁺-K⁺-ATPase·c-Src dependent NADPH oxidase/ROS pathway was also involved in the effects of ouabain and DRm217 on HG-induced cell injury. These novel results may help us to understand the important role of the Na⁺-K⁺-ATPase in diabetic cardiovascular diseases.

Inhibition of DPP-4 Activity and Neuronal Atrophy with Genistein Attenuates Neurological Deficits Induced by Transient Global Cerebral Ischemia and Reperfusion in Streptozotocin-Induced Diabetic Mice

Genistein, an isoflavonoid phytoestrogen, has been known for its potential pharmacological properties especially for neuroprotection and treating diabetes. The present study aims to determine the neuroprotective efficacy of genistein against global cerebral ischemia-reperfusion-induced neuronal injury in streptozotocin-induced diabetic mice and explore the underlying mechanisms. Streptozotocin-induced diabetic mice were subjected to transient cerebral ischemia by occluding both common carotid arteries for 30 min followed by 24 h reperfusion to induce neuronal injury. Effect of genistein (2.5, 5.0, and 10.0 mg/kg, i.p., o.d.) treatment on ischemia-reperfusion-induced neuronal injury in diabetic mice was evaluated in terms of cerebral infarct size, oxidative damage, mitochondrial activity in terms of neuronal apoptosis and cellular viability, dipeptidyl peptidase-4 activity and active glucagon-like peptide-1 concentration, and neurological functions measured as short-term memory and motor performance. Genistein administration following transient cerebral ischemia significantly (p ˂ 0.0001) counteracted cognitive impairment and re-established (p ˂ 0.001) motor performance in diabetic mice. Ischemia-reperfusion increased the infarct size, genistein administration prevented the increase in cerebral infarct size (p ˂ 0.0001) and significantly suppressed (p ˂ 0.001) the increase in cerebral oxidative stress in transient cerebral ischemia-reperfusion subjected diabetic mice. Genistein treatment significantly (p ˂ 0.001) reduced neuronal apoptosis and increased cellular viability (p ˂ 0.0001), almost completely suppressed (p ˂ 0.0001) the circulating dipeptidyl peptidase-4 activity, and enhanced (p ˂ 0.0001) glucagon-like peptide-1 concentration in diabetic mice with cerebral ischemia-reperfusion. This study suggests that genistein has potent neuroprotective activity against global cerebral ischemia-reperfusion-induced neuronal injury and consequent neurological deficits in streptozotocin-induced diabetic mice.

Zinc Is Indispensable in Exercise-Induced Cardioprotection against Intermittent Hypoxia-Induced Left Ventricular Function Impairment in Rats

In obstructive sleep apnea (OSA), recurrent obstruction of the upper airway leads to intermittent hypoxia (IH) during sleep, which can result in impairment of cardiac function. Although exercise can have beneficial effects against IH-induced cardiac dysfunction, the mechanism remains unclear. This study aimed to investigate the interactions of zinc and exercise on IH-triggered left ventricular dysfunction in a rat model that mimics IH in OSA patients. Nine-week-old male Sprague-Dawley rats were randomly assigned to either a control group (CON) or to a group receiving 10 weeks of exercise training (EXE). During weeks 9 and 10, half the rats in each group were subjected to IH for 8 h per day for 14 days (IHCON, IHEXE), whereas the remainder continued to breathe room air. Rats within each of the CON, IHCON, EXE, and IHEXE groups were further randomly assigned to receive intraperitoneal injections of either zinc chloride, the zinc chelator N,N,N',N'-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN), or injection vehicle only. IH induced a lower left ventricular fractional shortening, reduced ejection fraction, higher myocardial levels of inflammatory factors, increased levels oxidative stress, and lower levels of antioxidative capacity, all of which were abolished by zinc treatment. IHEXE rats exhibited higher levels of cardiac function and antioxidant capacity and lower levels of inflammatory factors and oxidative stress than IHCON rats; however, IHEXE rats receiving TPEN did not exhibit these better outcomes. In conclusion, zinc is required for protecting against IH-induced LV functional impairment and likely plays a critical role in exercise-induced cardioprotection by exerting a dual antioxidant and anti-inflammatory effect.

Activation of Na+/K+-ATPase attenuates high glucose-induced H9c2 cell apoptosis via suppressing ROS accumulation and MAPKs activities by DRm217

Hyperglycemia is one of the major factors responsible for the myocardial apoptosis and dysfunction in diabetes. Many studies have proved that there is a close relationship between decreased Na⁺/K⁺-ATPase activity and diabetic cardiomyopathy. However, the effect of directly activated Na⁺/K⁺-ATPase on high glucose-induced myocardial injury is still unknown. Here we found that DRm217, a Na⁺/K⁺-ATPase's DR-region specific monoclonal antibody and direct activator, could prevent high glucose-induced H9c2 cell injury, reactive oxygen species (ROS) release, and mitochondrial dysfunction. High glucose-treatment decreased Na⁺/K⁺-ATPase activity and increased intracellular Ca²⁺ level, whereas DRm217 increased Na⁺/K⁺-ATPase activity and alleviated Ca²⁺ overload. Inhibition of Ca²⁺ overload or closing sodium calcium exchanger (NCX channel) could reverse high glucose-induced ROS increasing and cell injury. In addition, DRm217 could significantly attenuate high glucose-induced p38, JNK and ERK1/2 phosphorylation, which were involved in high glucose-induced cell injury and ROS accumulation. Our findings suggest that DRm217 may protect against the deleterious effects of high glucose in the heart. Prevention of high glucose-induced myocardial cell injury by specific Na⁺/K⁺-ATPase activator may be an attractive therapeutic option.

Assessment of the Protective Role of Prenatal Zinc versus Insulin Supplementation on Fetal Cardiac Damage Induced by Maternal Diabetes in Rat Using Caspase-3 and KI67 Immunohistochemical Stains

Maternal diabetes mellitus (DM) affects early organogenesis. Metabolic disorders of DM are associated with a depleted zinc status. This study evaluated the effect of maternal DM on cardiac development of rat fetuses and protective roles of prenatal zinc versus insulin supplementation. Pregnant rats were divided into 4 groups ((I) control, (II) STZ-induced DM, (III) STZ-induced DM treated with Zn, and (IV) STZ induced DM treated with insulin), all sacrificed on GD 20. Fetal heart weight of diabetic rats showed significant decrease compared to controls (P < 0.05). H&E stained section of controls had normal appearance of the myocardium, compared to diabetics that showed myocardial disarray with characteristic degenerative changes. Sections of zinc treated group showed restored architecture of normal myofibrils with minimal degenerative changes, while those of insulin treated group show partial restoration of the normal architecture of cardiomyocytes with focal improvement of cardiac tissue. Caspase-3 immunostained slides showed positive cytoplasmic immunoreactivity in diabetic group. But KI67 immunostained slides revealed negative nuclear immunoreaction in diabetics. We observed that gestational diabetes was associated with increased risk of fetal myocardial damage that might be caused by increased apoptotic level. Treating diabetic pregnant subjects with zinc and insulin was associated with improvement in myocardial integrity.

Investigating the Mechanism of Hyperglycemia-Induced Fetal Cardiac Hypertrophy

Hyperglycemia in diabetic mothers enhances the risk of fetal cardiac hypertrophy during gestation. However, the mechanism of high-glucose-induced cardiac hypertrophy is not largely understood. In this study, we first demonstrated that the incidence rate of cardiac hypertrophy dramatically increased in fetuses of diabetic mothers using color ultrasound examination. In addition, human fetal cardiac hypertrophy was successfully mimicked in a streptozotocin (STZ)-induced diabetes mouse model, in which mouse cardiac hypertrophy was diagnosed using type-M ultrasound and a histological assay. PH3 immunofluorescent staining of mouse fetal hearts and in vitro-cultured H9c2 cells indicated that cell proliferation decreased in E18.5, E15.5 and E13.5 mice, and cell apoptosis in H9c2 cells increased in the presence of high glucose in a dose-dependent manner. Next, we found that the individual cardiomyocyte size increased in pre-gestational diabetes mellitus mice and in response to high glucose exposure. Meanwhile, the expression of β-MHC and BMP-10 was up-regulated. Nkx2.5 immunofluorescent staining showed that the expression of Nkx2.5, a crucial cardiac transcription factor, was suppressed in the ventricular septum, left ventricular wall and right ventricular wall of E18.5, E15.5 and E13.5 mouse hearts. However, cardiac hypertrophy did not morphologically occur in E13.5 mouse hearts. In cultured H9c2 cells exposed to high glucose, Nkx2.5 expression decreased, as detected by both immunostaining and western blotting, and the expression of KCNE1 and Cx43 was also restricted. Taken together, alterations in cell size rather than cell proliferation or apoptosis are responsible for hyperglycemia-induced fetal cardiac hypertrophy. The aberrant expression of Nkx2.5 and its regulatory target genes in the presence of high glucose could be a principal component of pathogenesis in the development of fetal cardiac hypertrophy.

Inhibitory effect of zinc on the advanced glycation end product-induced apoptosis of mouse osteoblastic cells

Osteoporosis and diabetes have become serious health problems worldwide. Previous studies have suggested that diabetes is associated with osteoporosis and increased fracture risk. However, the mechanism underlying diabetes‑induced osteoporosis remains to be elucidated. Therefore, the present study aimed to examine the mechanism underlying diabetes‑induced osteoporosis, and determine the protective effects of zinc, which is known to be closely associated with osteoporosis and diabetes. The results of the present study demonstrated that zinc inhibited advanced glycation end product (AGE)‑induced MC3T3‑E1 cell apoptosis by attenuating the production of reactive oxygen species, inhibiting caspase‑3 and caspase‑9 activation, and inhibiting the release of cytochrome c from between the mitochondria and the cytosol. Furthermore, zinc was found to protect cells against AGE‑induced apoptosis via the mitogen‑activated protein kinase/extracellular signal‑regulated kinase and phosphoinositide 3‑kinase/AKT signaling pathways. In conclusion, these findings enable a better understanding of the mechanism underlying diabetes‑induced osteoporosis, and may indicate a novel target for its prevention and treatment.

Stimulatory Effects of Balanced Deep Sea Water on Mitochondrial Biogenesis and Function

The worldwide prevalence of metabolic diseases, including obesity and diabetes, is increasing. Mitochondrial dysfunction is recognized as a core feature of these diseases. Emerging evidence also suggests that defects in mitochondrial biogenesis, number, morphology, fusion, and fission, contribute to the development and progression of metabolic diseases. Our previous studies revealed that balanced deep-sea water (BDSW) has potential as a treatment for diabetes and obesity. In this study, we aimed to investigate the mechanism by which BDSW regulates diabetes and obesity by studying its effects on mitochondrial metabolism. To determine whether BDSW regulates mitochondrial biogenesis and function, we investigated its effects on mitochondrial DNA (mtDNA) content, mitochondrial enzyme activity, and the expression of transcription factors and mitochondria specific genes, as well as on the phosphorylation of signaling molecules associated with mitochondria biogenesis and its function in C₂C₁₂ myotubes. BDSW increased mitochondrial biogenesis in a time and dose-dependent manner. Quantitative real-time PCR revealed that BDSW enhances gene expression of PGC-1α, NRF1, and TFAM for mitochondrial transcription; MFN1/2 and DRP1 for mitochondrial fusion; OPA1 for mitochondrial fission; TOMM40 and TIMM44 for mitochondrial protein import; CPT-1α and MCAD for fatty acid oxidation; CYTC for oxidative phosphorylation. Upregulation of these genes was validated by increased mitochondria staining, CS activity, CytC oxidase activity, NAD⁺ to NADH ratio, and the phosphorylation of signaling molecules such as AMPK and SIRT1. Moreover, drinking BDSW remarkably improved mtDNA content in the muscles of HFD-induced obese mice. Taken together, these results suggest that the stimulatory effect of BDSW on mitochondrial biogenesis and function may provide further insights into the regulatory mechanism of BDSW-induced anti-diabetic and anti-obesity action.

Influence of intracellular zinc on cultures of rat cardiac neural crest cells

BACKGROUND

Developmental zinc (Zn) deficiency increases the incidence of heart anomalies in rat fetuses, in regions and structures derived from the outflow tract. Given that the development of the outflow tract requires the presence of cardiac neural crest cells (cNCC), we speculated that Zn deficiency selectively kills cNCC and could lead to heart malformations.

METHODS

Cardiac NCC were isolated from E10.5 rat embryos and cultured in control media (CTRL), media containing 3 μM of the cell permeable metal chelator N, N, N', N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN), or in TPEN-treated media supplemented with 3 μM Zn (TPEN + Zn). Cardiac NCC were collected after 6, 8, and 24 h of treatment to assess cell viability, proliferation, and apoptosis.

RESULTS

The addition of TPEN to the culture media reduced free intracellular Zn pools and cell viability as assessed by low ATP production, compared to cells grown in control or Zn-supplemented media. There was an accumulation of reactive oxygen species, a release of mitochondrial cytochrome c into the cytoplasm, and an increased cellular expression of active caspase-3 in TPEN-treated cNCC compared to cNCC cultured in CTRL or TPEN + Zn media.

CONCLUSION

Zn deficiency can result in oxidative stress in cNCC, and subsequent decreases in their population and metabolic activity. These data support the concept that Zn deficiency associated developmental heart defects may arise in part as a consequence of altered cNCC metabolism.

Modulation of glucose metabolism by balanced deep-sea water ameliorates hyperglycemia and pancreatic function in streptozotocin-induced diabetic mice

The aim of this study was to determine the effects of balanced deep-sea water (BDSW) on hyperglycemia and glucose intolerance in streptozotocin (STZ)-induced diabetic mice. BDSW was prepared by mixing DSW mineral extracts and desalinated water to yield a final hardness of 1000–4000 ppm. Male ICR mice were assigned to 6 groups; mice in each group were given tap water (normal and STZ diabetic groups) or STZ with BDSW of varying hardness (0, 1000, 2000, and 4000 ppm) for 4 weeks. The STZ with BDSW group exhibited lowered fasting plasma glucose levels than the STZ-induced diabetic group. Oral glucose tolerance tests showed that BDSW improves impaired glucose tolerance in STZ-induced diabetic mice. Histopathological evaluation of the pancreas showed that BDSW restores the morphology of the pancreatic islets of Langerhans and increases the secretion of insulin in STZ-induced diabetic mice. Quantitative real-time PCR assay revealed that the expression of hepatic genes involved in gluconeogenesis, glucose oxidation, and glycogenolysis was suppressed, while the expression of the genes involved in glucose uptake, β-oxidation, and glucose oxidation in muscle were increased in the STZ with BDSW group. BDSW stimulated PI3-K, AMPK, and mTOR pathway-mediated glucose uptake in C₂C₁₂ myotubes. BDSW increased AMPK phosphorylation in C₂C₁₂ myotubes and improved impaired AMPK phosphorylation in the muscles of STZ-induced diabetic mice. Taken together, these results suggest that BDSW is a potential anti-diabetic agent, owing to its ability to suppress hyperglycemia and improve glucose intolerance by modulating glucose metabolism, recovering pancreatic islets of Langerhans and increasing glucose uptake.

ZIP1 and zinc inhibits fluoride-induced apoptosis in MC3T3-E1 cells

Excess fluoride intake could induce apoptosis in the cells. As an essential micronutrient and cytoprotectant, zinc is involved in many types of apoptosis. Here, we studied the effects of zinc and ZIP1 on fluoride-induced apoptosis in mouse MC3T3-E1 cells and examined the underlying molecular mechanisms. Our study found that fluoride not only inhibited cell proliferation and increased the intracellular reactive oxygen species (ROS) but also induced cell apoptosis. Whereas pretreatment with zinc significantly attenuated fluoride-induced ROS production and partly protected cells against fluoride-induced apoptosis through MAPK/ERK signaling pathway. Our study also found that fluoride upregulated the expression of ZIP1 in a time-dependent manner. Moreover, overexpression of ZIP1 also inhibited fluoride-induced apoptosis by activation of PI3K/Akt pathway. This cytoprotective effect of zinc and ZIP1 may be new factors that affect the physiological activity of fluoride and need study further.

Zinc rescue of Akt2 gene deletion-linked murine cardiac dysfunction and pathological changes is metallothionein-dependent

We have demonstrated that zinc supplementation provides cardiac protection from diabetes in mice, but its underlying mechanism remains unclear. Since zinc mimics the function of insulin, it may provide benefit to the heart via stimulating Akt-mediated glucose metabolism. Akt2 plays an important role in cardiac glucose metabolism and mice with Akt2 gene deletion (Akt2-KO) exhibit a type 2 diabetes phenotype; therefore, we assumed that no cardiac protection by zinc supplementation from diabetes would be observed in Akt2-KO mice. Surprisingly, despite Akt2 gene deletion, zinc supplementation provided protection against cardiac dysfunction and other pathological changes in Akt2-KO mice, which were accompanied by significant decreases in Akt and GSK-3β phosphorylation. Correspondingly, glycogen synthase phosphorylation and hexokinase II and PGC-1α expression, all involved in the regulation of glucose metabolism, were significantly altered in diabetic hearts, along with a significantly increased expression of Akt negative regulators: PTEN, PTP1B, and TRB3. All these molecular, pathological, and functional changes were significantly prevented by 3-month zinc supplementation. Furthermore, the stimulation of Akt-mediated glucose metabolic kinases or enzymes by zinc treatment was metallothionein-dependent since it could not be observed in metallothionein-knockout mice. These results suggest that zinc preserves cardiac function and structure in Akt2-KO mice presumably due to its insulin mimetic effect on cardiac glucose-metabolism. The cardioprotective effects of zinc are metallothionein-dependent. This is very important since zinc supplementation may be required for patients with Akt2 gene deficiency or insulin resistance.

Zinc modulates high glucose-induced apoptosis by suppressing oxidative stress in renal tubular epithelial cells

Hyperglycemia is a characteristic of diabetic nephropathy, inducing renal tubular cell apoptosis by eliciting oxidative stress and inflammation. Zinc (Zn) is known as an essential trace element in many enzymes and proteins involved in antioxidant defenses, electron transport, and exerting antiapoptotic or cytoprotective effects. In this study, the underlying mechanisms involved in the protective effects of Zn on high glucose-induced cytotoxicity were explored using cultured renal tubular epithelial cells (NRK-52E). The authors discovered that Zn supplementation inhibited high glucose (HG)-induced NRK-52E cell apoptosis by attenuating reactive oxygen species production, inhibiting HG-induced caspase-3 and caspase-9 activation, and inhibiting the release of cytochrome c from mitochondria to the cytosol. Further analysis revealed that Zn supplementation facilitated cell survival through increasing nuclear translocation of NF-E2-related factor 2 (Nrf2), leading to increased regulation of levels of two antioxidant enzymes, hemeoxygenase-1 and glutamate cysteine ligase, which provided an adaptive survival response against the HG-induced oxidative cytotoxicity. Moreover, the Zn-mediated increases in Nrf2 activity were suppressed by the pharmacological inhibition of Akt or extracellular signal-regulated kinase 1/2. Taken together, these findings suggest that Zn antiapoptosis capacity through the activation of Akt and ERK signal pathways leads to Nrf2 activation and, subsequently, Nrf2 target gene induction, thereby protecting the NRK-52E cells from HG-induced apoptosis.

Ursolic acid prevents endoplasmic reticulum stress-mediated apoptosis induced by heat stress in mouse cardiac myocytes

Heat stress causes serious physiological dysfunction of cardiac myocytes and is associated with several types of cardiovascular diseases. However, the underlying mechanisms and therapeutic strategies to alleviate heat stress-induced myocardial damage are not available. The objective of this study was to (1) investigate the functional role of endoplasmic reticulum (ER) stress-mediated apoptosis in heat exposure-induced myocardial damage, and (2) to evaluate the effects of ursolic acid on the myocardial apoptosis as well as the underlying mechanisms in mouse cardiac myocytes. We show here that heat stress-induced apoptosis is predominantly mediated by the activation of PERK-eIF2α-CHOP unfolded protein response which up-regulates the protein expression of Puma, and by the modulation of cellular redox state. Intriguingly, the myocardial apoptosis is markedly attenuated by ursolic acid treatment. Mechanistically, the protective effects of ursolic acid are mediated, at least partly, by reestablishing the intracellular redox state and inducing the expression of the anti-apoptotic protein Mcl-1, which, in turn, inactivating CHOP-induced Puma up-regulation. The striking finding that ursolic acid has both anti-apoptotic and antioxidative activities against ER stress-associated myocardial damage suggests that supplementation of ursolic acid might be a potential strategy to reduce the detrimental effects of heat stress in cardiomyocytes.

Metallothionein - immunohistochemical cancer biomarker: a meta-analysis

Metallothionein (MT) has been extensively investigated as a molecular marker of various types of cancer. In spite of the fact that numerous reviews have been published in this field, no meta-analytical approach has been performed. Therefore, results of to-date immunohistochemistry-based studies were summarized using meta-analysis in this review. Web of science, PubMed, Embase and CENTRAL databases were searched (up to April 30, 2013) and the eligibility of individual studies and heterogeneity among the studies was assessed. Random and fixed effects model meta-analysis was employed depending on the heterogeneity, and publication bias was evaluated using funnel plots and Egger's tests. A total of 77 studies were included with 8,015 tissue samples (4,631 cases and 3,384 controls). A significantly positive association between MT staining and tumors (vs. healthy tissues) was observed in head and neck (odds ratio, OR 9.95; 95% CI 5.82-17.03) and ovarian tumors (OR 7.83; 1.09-56.29), and a negative association was ascertained in liver tumors (OR 0.10; 0.03-0.30). No significant associations were identified in breast, colorectal, prostate, thyroid, stomach, bladder, kidney, gallbladder, and uterine cancers and in melanoma. While no associations were identified between MT and tumor staging, a positive association was identified with the tumor grade (OR 1.58; 1.08-2.30). In particular, strong associations were observed in breast, ovarian, uterine and prostate cancers. Borderline significant association of metastatic status and MT staining were determined (OR 1.59; 1.03-2.46), particularly in esophageal cancer. Additionally, a significant association between the patient prognosis and MT staining was also demonstrated (hazard ratio 2.04; 1.47-2.81). However, a high degree of inconsistence was observed in several tumor types, including colorectal, kidney and prostate cancer. Despite the ambiguity in some tumor types, conclusive results are provided in the tumors of head and neck, ovary and liver and in relation to the tumor grade and patient survival.

Supplement zinc as an effective treatment for spinal cord ischemia/reperfusion injury in rats

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) plays a key role in the pathophysiology process and therapy of spinal cord injury (SCI). Accordingly, zinc regulates the expression of BDNF and its receptor in the central nervous system, the mechanism of which is still unknown. The present study investigates whether supplement zinc could reduce neurological damage in a rat model, with spinal cord ischemia-reperfusion (I/R) injury and how the effect of zinc transporter 1(ZnT-1) was involved.

METHODS

100 Sprague-Dawley male rats were randomly and evenly divided into four groups. They were subjected to spinal cord ischemia by clamping the abdominal aorta for 45 min. Rats in the zinc-deficient dietary model group (ZD), zinc-adequate dietary model group (ZA), and zinc-high dietary model group (ZH) were given free access to purified diet, containing 5, 30, or 180 mg Zn/kg. Sham operation rats were subjected to laparotomy without clamping of the aorta and were fed by ZA diet (30 mg Zn/kg). Neurological function was scored by Tarlov's score. The spinal cord segments (L5) were harvested for histological examination, auto-metallographic (AMG) analysis, myeloperoxidase (MPO) activity analysis, expression of ZnT-1 and BDNF.

RESULTS

The rats in the ZH group have shown the higher neurological scores, slighter histological changes and the attenuated MPO activity, compared with those in the ZD and ZA groups at the four observation time points (p<0.05). The AMG staining density in the ZH group was significantly higher than that of ZD group in 14 days later after the operation. Compared with other groups, ZH group's expression of Zn-T1 and BDNF were significantly increased, and was positively correlated with the same time points after surgery (Spearman rho=0.403, p=0.0152.)

CONCLUSION

These findings suggest that zinc supplement can significantly reduce the spinal cord I/R injury in rats. The mechanism may be related with restraining the MPO activity and increasing of ZnT-1, which promoted the synthesis and release of BDNF.

Subacute zinc administration and L-NAME caused an increase of NO, zinc, lipoperoxidation, and caspase-3 during a cerebral hypoxia-ischemia process in the rat

Zinc or L-NAME administration has been shown to be protector agents, decreasing oxidative stress and cell death. However, the treatment with zinc and L-NAME by intraperitoneal injection has not been studied. The aim of our work was to study the effect of zinc and L-NAME administration on nitrosative stress and cell death. Male Wistar rats were treated with ZnCl₂ (2.5 mg/kg each 24 h, for 4 days) and N-ω-nitro-L-arginine-methyl ester (L-NAME, 10 mg/kg) on the day 5 (1 hour before a common carotid-artery occlusion (CCAO)). The temporoparietal cortex and hippocampus were dissected, and zinc, nitrites, and lipoperoxidation were assayed at different times. Cell death was assayed by histopathology using hematoxylin-eosin staining and caspase-3 active by immunostaining. The subacute administration of zinc before CCAO decreases the levels of zinc, nitrites, lipoperoxidation, and cell death in the late phase of the ischemia. L-NAME administration in the rats treated with zinc showed an increase of zinc levels in the early phase and increase of zinc, nitrites, and lipoperoxidation levels, cell death by necrosis, and the apoptosis in the late phase. These results suggest that the use of these two therapeutic strategies increased the injury caused by the CCAO, unlike the alone administration of zinc.

Zinc homeostasis in the metabolic syndrome and diabetes

Zinc (Zn) is an essential mineral that is required for various cellular functions. Zn dyshomeostasis always is related to certain disorders such as metabolic syndrome, diabetes and diabetic complications. The associations of Zn with metabolic syndrome, diabetes and diabetic complications, thus, stem from the multiple roles of Zn: (1) a constructive component of many important enzymes or proteins, (2) a requirement for insulin storage and secretion, (3) a direct or indirect antioxidant action, and (4) an insulin-like action. However, whether there is a clear cause-and-effect relationship of Zn with metabolic syndrome, diabetes, or diabetic complications remains unclear. In fact, it is known that Zn deficiency is a common phenomenon in diabetic patients. Chronic low intake of Zn was associated with the increased risk of diabetes and diabetes also impairs Zn metabolism. Theoretically Zn supplementation should prevent the metabolic syndrome, diabetes, and diabetic complications; however, limited available data are not always supportive of the above notion. Therefore, this review has tried to summarize these pieces of available information, possible mechanisms by which Zn prevents the metabolic syndrome, diabetes, and diabetic complications. In the final part, what are the current issues for Zn supplementation were also discussed.

Differential gene expression profiles during embryonic heart development in diabetic mice pregnancy

Congenital heart defects (CHD) are one of the most common defects in offspring of diabetic mothers. There is a clear association between maternal diabetes and CHD; however the underlying molecular mechanism remains unknown. We hypothesized that maternal diabetes affects with the expression of early developmental genes that regulate the essential developmental processes of the heart, thereby resulting in the pathogenesis of CHD. We analyzed genome-wide expression profiling in the developing heart of embryos from diabetic and control mice by using the oligonucleotide microarray. Microarray analysis revealed that a total of 878 genes exhibited more than 1.5 fold changes in expression level in the hearts of experimental embryos in either E13.5 or E15.5 compared with their respective controls. Expression pattern of genes that is differentially expressed in the developing heart was further examined by the real-time reverse transcriptase-polymerase chain reaction. Several genes involved in a number of molecular signaling pathways such as apoptosis, proliferation, migration and differentiation in the developing heart were differentially expressed in embryos of diabetic pregnancy. It is concluded that altered expression of several genes involved in heart development may contribute to CHD in offspring of diabetic mothers.

Zinc-induced cardiomyocyte relaxation in a rat model of hyperglycemia is independent of myosin isoform

It has been reported previously that diabetic cardiomyopathy can be inhibited or reverted with chronic zinc supplementation. In the current study, we hypothesized that total cardiac calcium and zinc content is altered in early onset diabetes mellitus characterized in part as hyperglycemia (HG) and that exposure of zinc ion (Zn²⁺) to isolated cardiomyocytes would enhance contraction-relaxation function in HG more so than in nonHG controls. To better control for differential cardiac myosin isoform expression as occurs in rodents after β-islet cell necrosis, hypothyroidism was induced in 16 rats resulting in 100% β-myosin heavy chain expression in the heart. β-Islet cell necrosis was induced in half of the rats by streptozocin administration. After 6 wks of HG, both HG and nonHG controls rats demonstrated similar myofilament performance measured as thin filament calcium sensitivity, native thin filament velocity in the myosin motility assay and contractile velocity and power. Extracellular Zn²⁺ reduced cardiomyocyte contractile function in both groups, but enhanced relaxation function significantly in the HG group compared to controls. Most notably, a reduction in diastolic sarcomere length with increasing pacing frequencies, i.e., incomplete relaxation, was more pronounced in the HG compared to controls, but was normalized with extracellular Zn²⁺ application. This is a novel finding implicating that the detrimental effect of HG on cardiomyocyte Ca²⁺ regulation can be amelioration by Zn²⁺. Among the many post-translational modifications examined, only phosphorylation of ryanodine receptor (RyR) at S-2808 was significantly higher in HG compared to nonHG. We did not find in our hypothyroid rats any differentiating effects of HG on myofibrillar protein phosphorylation, lysine acetylation, O-linked N-acetylglucosamine and advanced glycated end-products, which are often implicated as complicating factors in cardiac performance due to HG. Our results suggest that the relaxing effects of Zn²⁺ on cardiomyocyte function are more pronounced in the HG state due an insulin-dependent effect of enhancing removal of cytosolic Ca²⁺ via SERCA2a or NCX or by reducing Ca²⁺ influx via L-type channel or Ca²⁺ leak through the RyR. Investigations into the effects of Zn²⁺ on these mechanisms are now underway.