Cardiac abnormalities induced by zinc deficiency are associated with alterations in the expression of genes regulated by the zinc-finger transcription factor GATA-4

Sex-specific transcriptomic effects of low-dose inorganic arsenic exposure on bone marrow-derived macrophages

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. There are numerous diseases caused by iAs exposure in which macrophages are involved, including cardiovascular disease, cancer, and increased risk of (respiratory) infectious diseases. Notably, prenatal iAs exposure is also associated with negative birth outcomes and developmental immunotoxicity (DIT) contributing to long-term adverse outcomes of these immune-related diseases. Therefore, understanding the effects of iAs exposure on macrophages, particularly during immune development or tissue injury and inflammation, can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In contrast to prior published studies which often only focused on the effect of iAs on mature macrophages after development, in this study, we analyzed the transcriptome of M0-, M1- and M2-polarized male and female murine bone marrow-derived macrophages (BMDMs) which were exposed to iAs during the differentiation phase, as a model to study iAs (developmental) immunotoxicity. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure during differentiation. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding the role of (early-life) arsenic exposure in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

Diabetic cardiomyopathy - Zinc preventive and therapeutic potentials by its anti-oxidative stress and sensitizing insulin signaling pathways

Oxidative stress and insulin resistance are two key mechanisms for the development of diabetic cardiomyopathy (DCM, cardiac remodeling and dysfunction). In this review, we discussed how zinc and metallothionein (MT) protect the heart from type 1 or type 2 diabetes (T1D or T2D) through its anti-oxidative function and insulin-mediated PI3K/Akt signaling activation. Both T1D and T2D-induced DCM, shown by cardiac structural remodeling and dysfunction, in wild-type mice, but not in cardiomyocyte-specific overexpressing MT mice. In contrast, mice with global MT gene deletion were more susceptible to the development of DCM. When we used zinc to treat mice with either T1D or T2D, cardiac remodeling and dysfunction were significantly prevented along with increased cardiac MT expression. To support the role of zinc homeostasis in insulin signaling pathways, treatment of diabetic mice with zinc showed the preservation of phosphorylation levels of insulin-mediated glucose metabolism-related Akt2 and GSK-3β and even rescued cardiac pathogenesis induced by global deletion of Akt2 gene in a MT-dependent manner. These results suggest the protection by zinc from DCM is through both the induction of MT and sensitization of insulin signaling. Combined our own and other works, this review comprehensively summarized the roles of zinc homeostasis in the development and progression of DCM and its therapeutic implications. At the end, we provided pre-clinical and clinical evidence for the preventive and therapeutic potential of zinc supplementation through its anti-oxidative stress and sensitizing insulin signaling actions. Understanding the intricate connections between zinc and DCM provides insights for the future interventional approaches.

Transcriptomic Effects of Low-Dose Inorganic Arsenic Exposure on Murine Bone Marrow-Derived Macrophages

Both tissue-resident macrophages and monocytes recruited from the bone marrow that transform into tissue-resident cells play critical roles in mediating homeostasis as well as in the pathology of inflammatory diseases. Inorganic arsenic (iAs) is the most common drinking water contaminant worldwide and represents a major public health concern. Several diseases that macrophages have implicated involvement in are caused by iAs exposure, including cardiovascular disease, cancer, and increased risk of infectious disease. Therefore, understanding the effects of iAs exposure on macrophages can help us better grasp the full range of arsenic immunotoxicity and better design therapeutic targets for iAs-induced diseases particularly in exposed populations. In this study, we analyzed the transcriptome of low dose iAs-exposed male and female murine bone marrow-derived macrophages (BMDMs) with either M0, M1, or M2 stimulation. We identified differentially expressed genes by iAs in a sex- and stimulation-dependent manner and used bioinformatics tools to predict protein-protein interactions, transcriptional regulatory networks, and associated biological processes. Overall, our data suggest that M1-stimulated, especially female-derived, BMDMs are most susceptible to iAs exposure. Most notably, we observed significant downregulation of major proinflammatory transcription factors, like IRF8, and its downstream targets, as well as genes encoding proteins involved in pattern recognition and antigen presentation, such as TLR7, TLR8, and H2-D1, potentially providing causal insight regarding arsenic's role in perturbing immune responses to infectious diseases. We also observed significant downregulation of genes involved in processes crucial to coordinating a proinflammatory response including leukocyte migration, differentiation, and cytokine and chemokine production and response. Finally, we discovered that 24 X-linked genes were dysregulated in iAs-exposed female stimulation groups compared to only 3 across the iAs-exposed male stimulation groups. These findings elucidate the potential mechanisms underlying the sex-differential iAs-associated immune-related disease risk.

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.

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.

Association of Zinc and Copper Status with Cardiovascular Diseases and their Assessment Methods: A Review Study

Cardiovascular disease (CVD) is the leading cause of mortality, morbidity, and financial losses and has a high prevalence across the world. Several studies have investigated the association between various CVD types with zinc and copper status as the essential minerals for the human body, proposing contradictory and similar results. This narrative review aimed to survey the correlations between zinc and copper status in the human body and some risk factors of CVD, as well as the assessment methods of zinc and copper status in the human body. According to the reviewed articles, zinc and copper deficiency may increase the risk of coronary heart disease, valvular regurgitation, and myocardial lesions, cardiac hypertrophy. Furthermore, it could lead to the expanded mitochondrial compartments of the heart, acute and chronic heart failure, and elevation of inflammation markers, such as interleukin-1 (IL-1) and IL-6. Two methods are primarily used for the assessment of zinc and copper in the human body, including the direct method (measurement of their concentrations) and indirect method (determining the activity of zinc- and copper-containing enzymes). Both these methods are considered reliable for the assessment of the zinc and copper levels in healthy individuals. Serum or plasma levels of these elements are also commonly used for the assessment of the correlation between zinc and copper status and CVD. But, which one is a more accurate indicator in relation to CVD is not yet clear; therefore, further studies are required in this field.

Maternal serum zinc concentration and neural tube defects in offspring: a meta-analysis

OBJECTIVE

This study was to assess the relationship between maternal serum zinc concentration and NTDs in offspring by conducting a meta-analysis.

METHODS

We searched Pubmed, Medline and Web of Science for all English studies about the relationship between maternal serum zinc level and NTDs in offspring (published between 1 January 1975 and 1 January 2020). Pooled effect sizes with corresponding 95% CIs were calculated using a random-effect model by Revman 5.3 and Stata 15.1 software.

RESULTS

Eight articles met our selection criteria and a total of 187 cases and 894 controls were included in this meta-analysis. Our results showed that mothers with NTDs infants had lower serum zinc concentration than those with healthy infants (SMD= -0.77, 95%CI [-1.16, -0.37], p = .0001, I ² = 73%).

CONCLUSIONS

Compared with mothers with healthy infants, mothers with NTDs infants have lower serum zinc levels, suggesting that low maternal serum zinc level during pregnancy is probably associated with the risk of NTDs in offspring. But the mechanism of the association remains to be ascertained by large-scale cohort studies.

Zinc deficiency induces abnormal development of the myocardium by promoting SENP5 overexpression

Gestational zinc deficiency is a cause of congenital heart disease in the fetus, and sentrin/small ubiquitin-like modifier (SUMO)-specific proteases (SENPs) as deSUMOylation enzymes play a crucial role in the development of cardiac structures. However, current studies of the regulation and function of SENP in zinc-deficient status during heart development remain limited. In this study, SUMO1 modification was found to gradually decrease during heart development, and the level of SENP5 exhibited a similar trend to SUMO1 conjugation. In addition, zinc deficiency resulted in cardiac dysplasia, increased cell apoptosis, decreased cell viability, and differentiation inhibition of hiPSC-CMs. In order to investigate the function of SENP5 in zinc deficiency, hiPSC-CMs were transfected with SENP5 small interfering RNA. The negative effects of zinc lacking conditions were reversed with depletion of SENP5. It was confirmed that zinc deficiency induced abnormal differentiation of hiPSCs and increased apoptosis of hiPSC-CMs by promoting SENP5 overexpression, which led to cardiac dysplasia. Thus, it was concluded that SENP5 regulates the SUMO1 deconjugation during heart development and zinc deficiency may reduce conjugated SUMO by promoting SENP5 overexpression, which induces abnormal development of the myocardium.

Zinc and Zinc Transporters: Novel Regulators of Ventricular Myocardial Development

Ventricular myocardial development is a well-orchestrated process involving different cardiac structures, multiple signal pathways, and myriad proteins. Dysregulation of this important developmental event can result in cardiomyopathies, such as left ventricle non-compaction, which affect the pediatric population and the adults. Human and mouse studies have shed light upon the etiology of some cardiomyopathy cases and highlighted the contribution of both genetic and environmental factors. However, the regulation of ventricular myocardial development remains incompletely understood. Zinc is an essential trace metal with structural, enzymatic, and signaling function. Perturbation of zinc homeostasis has resulted in developmental and physiological defects including cardiomyopathy. In this review, we summarize several mechanisms by which zinc and zinc transporters can impact the regulation of ventricular myocardial development. Based on our review, we propose that zinc deficiency and mutations of zinc transporters may underlie some cardiomyopathy cases especially those involving ventricular myocardial development defects.

Maternal and neonatal micronutrient levels in newborns with CHD

OBJECTIVE

It is suggested that folic acid and/or multivitamins, taken periconceptionally, have a role in the prevention of many congenital anomalies. The aim of this study was to determine the serum micronutrient levels in mother-infant pairs with CHD compared with those with healthy newborns and their mothers.

METHODS

Serum levels of folic acid, homocysteine, zinc, vitamin A, vitamin D, and vitamin B12 were measured from 108 newborns with CHD (study group) and 103 healthy newborns (control group). The mothers' micronutrient levels were also measured simultaneously.

RESULTS

When compared with healthy newborns, for both maternal and neonatal data, homocysteine and zinc levels were higher and vitamin D levels were lower in the study group. In multivariate analysis, only maternal high zinc levels were associated with CHD in the newborns (p=0.02, OR: 0.9, 95% CI 0.8-0.9). The results did not change when analysed for truncal anomalies including truncus arteriosus, tetralogy of Fallot, and d-transposition of great arteries. There were positive correlations between maternal and neonatal levels of micronutrients, except vitamin B12.

CONCLUSION

We thought that high homocysteine and zinc levels and low vitamin D levels in mother-infant pairs might have a role in the aetiopathogenesis of CHD. Large-scale, prospective studies are needed to clarify the role of micronutrients in CHDs.

Experience with genomic sequencing in pediatric patients with congenital cardiac defects in a large community hospital

BACKGROUND

Congenital cardiac defects, whether isolated or as part of a larger syndrome, are the most common type of human birth defect occurring on average in about 1% of live births depending on the malformation. As there is an expanding understanding of the underlying molecular mechanisms by which a cardiac defect may occur, there is a need to assess the current rates of diagnosis of cardiac defects by molecular sequencing in a clinical setting.

METHODS AND RESULTS

In this report, we evaluated 34 neonatal and pediatric patients born with a cardiac defect and their parents using exomized preexisting whole genome sequencing (WGS) data to model clinically available exon-based tests. Overall, we identified candidate variants in previously reported cardiac-related genes in 35% (12/34) of the probands. These include clearly pathogenic variants in two of 34 patients (6%) and variants of uncertain significance in relevant genes in 10 patients (26%), of these latter 10, 2 segregated with clinically apparent findings in the family trios.

CONCLUSIONS

These findings suggest that with current knowledge of the proteins underlying CHD, genomic sequencing can identify the underlying genetic etiology in certain patients; however, this technology currently does not have a high enough yield to be of routine clinical use in the screening of pediatric congenital cardiac defects.

Zinc transporter Slc39a8 is essential for cardiac ventricular compaction

Isolated left ventricular noncompaction (LVNC) results from excessive trabeculation and impaired myocardial compaction during heart development. The extracellular matrix (ECM) that separates endocardium from myocardium plays a critical but poorly understood role in ventricular trabeculation and compaction. In an attempt to characterize solute carrier family 39 member 8-null (Slc39a8-null) mice, we discovered that homozygous null embryos do not survive embryogenesis and exhibit a cardiac phenotype similar to human LVNC. Slc39a8 encodes a divalent metal cation importer that has been implicated in ECM degradation through the zinc/metal regulatory transcription factor 1 (Zn/MTF1) axis, which promotes the expression of ECM-degrading enzymes, including Adamts metalloproteinases. Here, we have shown that Slc39a8 is expressed by endothelial cells in the developing mouse heart, where it serves to maintain cellular Zn levels. Furthermore, Slc39a8-null hearts exhibited marked ECM accumulation and reduction of several Adamts metalloproteinases. Consistent with the in vivo observations, knockdown of SLC39A8 in HUVECs decreased ADAMTS1 transcription by decreasing cellular Zn uptake and, as a result, MTF1 transcriptional activity. Our study thus identifies a gene underlying ventricular trabeculation and compaction development, and a pathway regulating ECM during myocardial morphogenesis.

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.

Correlation between congenital heart defects and maternal copper and zinc concentrations

BACKGROUND

The aim of this study was to investigate the correlation between maternal concentrations of copper and zinc and the risk of having an infant with a congenital heart defect (CHD).

METHODS

A multi-center hospital-based case-control study was conducted in China. A total of 212 cases and 212 controls were recruited from pregnant women who received prenatal examinations in four tertiary hospitals accredited to perform prenatal diagnosis in the cities of Shenzhen, Zhenzhou, Fuzhou and Wuhan between February 2010 and November 2011. Correlation between CHDs and maternal copper and zinc concentrations was estimated by a 1:1 conditional logistic regression. Also the interaction between copper and zinc was analyzed.

RESULTS

Compared with the controls, mothers with hair copper concentrations of 17.77 μg/g or more were more likely to have a child with a CHD than those with a lower concentration. The adjusted odds ratio was 5.70 (95% confidence interval, 2.58-12.61) for CHDs and 6.32 (95% confidence interval, 2.11-18.92) for conotruncal defects. Zinc concentrations were not significantly different in the case and control groups. The results suggest that mothers whose zinc content was 104.60 μg/g or less did not have a significantly higher risk of having a child with a CHD. No interaction between maternal copper and zinc concentrations was observed in the multiplicative or additive model.

CONCLUSION

Women with excessive copper concentrations have a significantly increased risk of having offspring with a CHD. A low maternal zinc status might have a correlation with CHDs, and an interaction between copper and zinc might exists, but an epidemiological study with a larger sample size is needed to confirm this finding.

Biological consequences of zinc deficiency in the pathomechanisms of selected diseases

From many points of view, zinc is one of the most important trace elements in biological systems. Many articles describe the well-known role of this metal in human physiology and pathophysiology, but in the related literature, there is a lack of current and reliable reviews of the role of zinc deficiency in many diseases. In this article, we describe the role of zinc deficiency in the oxidative stress control, immune response, proliferation, and pathogenesis and pathophysiology of selected diseases such as depression, cardiovascular diseases, diabetes mellitus, Alzheimer's disease, and Wilson's disease.

Morphological and functional effects on cardiac tissue induced by moderate zinc deficiency during prenatal and postnatal life in male and female rats

The aim of this study was to evaluate whether moderate zinc restriction in rats throughout fetal life, lactation, and/or postweaning growth results in early changes in cardiac morphology predisposing the onset of cardiac dysfunction in adult life as well as sex-related differences in the adaptation to this nutritional injury. Female Wistar rats received low or control zinc diets from the beginning of pregnancy up to offspring weaning. After being weaned, offspring were fed either a low or control zinc diet until 81 days. Systolic blood pressure was measured. Echocardiographic and electrocardiographic examinations, morphological experiments, and apoptosis by TUNEL assay were performed in the left ventricle. In the early stages, zinc-deficient male and female offspring showed an increase in cardiomyocyte diameter, probably associated with an increase in cardiac apoptotic cells, but smaller myocyte diameters in adulthood. In adult males, this nutritional injury induced decreased contractility and dilatation of the left ventricle, not allowing the heart to compensate the higher levels of blood pressure, and hypertrophic remodeling of coronary arteries associated with increased blood pressure. Adequate zinc intake during postweaning life did not overcome blood pressure levels but reversed some of the detrimental effects of earlier zinc deficiency in cardiac morphology and function. Females were less sensitive to this deficiency, exhibiting normal levels of blood pressure and no structural or functional heart alterations in adult life. The present study demonstrates that the effects of zinc deficiency on blood pressure, cardiac morphology, and function differ between sexes, with males more predisposed to develop cardiovascular diseases in adulthood.

Zinc restriction during different periods of life: influence in renal and cardiovascular diseases

Micronutrient undernutrition during critical periods of growth has become an important health issue in developing and developed countries, particularly among pregnant women and children having an imbalanced diet. Zinc is a widely studied microelement in infant feeding because it is a component of several enzymes involved in intermediary metabolism ranging from growth to cell differentiation and metabolism of proteins, carbohydrates, and lipids. Human and experimental studies have reported an association between zinc deficiency and the etiopathogenesis of cardiovascular and renal diseases like hypertension, atherosclerosis, congestive heart failure, coronary heart disease, and diabetes. The main links between the development of these pathologies and zinc deficiency are multiple mechanisms involving oxidative stress damage, apoptosis, and inflammation. A substantial body of evidence suggests that a poor in utero environment elicited by maternal dietary or placental insufficiency may "programme" susceptibility in the fetus to later development of cardiovascular, renal, metabolic, and endocrine diseases. Zinc deficiency in rats during intrauterine and postnatal growth can also be considered a model of fetal programming of cardiovascular and renal diseases in adult life. Dietary zinc restriction during fetal life, lactation, and/or postweaning induces an increase in arterial blood pressure and impairs renal function in adult life. This review focuses on the contributions of experimental and clinical studies to current knowledge of the physiologic role of zinc in the cardiovascular and renal systems. Moreover, this review examines the relationship between zinc deficiency during different periods of life and the development of cardiovascular and renal diseases in adult life.

The plausibility of maternal nutritional status being a contributing factor to the risk for fetal alcohol spectrum disorders: the potential influence of zinc status as an example

There is increasing evidence that human pregnancy outcome can be significantly compromised by suboptimal maternal nutritional status. Poor diet results in a maternal-fetal environment in which the teratogenicity of other insults such as alcohol might be amplified. As an example, there is evidence that zinc (Zn) can interact with maternal alcohol exposure to influence the risk for fetal alcohol spectrum disorders (FASD). Studies with experimental animals have shown that the teratogenicity of alcohol is increased under conditions of Zn deficiency, whereas its teratogenicity is lessened when animals are given Zn-supplemented diets or Zn injections before the alcohol exposure. Alcohol can precipitate an acute-phase response, resulting in a subsequent increase in maternal liver metallothionein, which can sequester Zn and lead to decreased Zn transfer to the fetus. Importantly, the teratogenicity of acute alcohol exposure is reduced in metallothionein knockout mice, which can have improved Zn transfer to the conceptus relative to wild-type mice. Consistent with the above, Zn status has been reported to be low in alcoholic women at delivery. Preliminary data from two basic science and clinical nutritional studies that are ongoing as part of the international Collaborative Initiative on Fetal Alcohol Spectrum Disorders support the potential role of Zn, among other nutritional factors, relative to risk for FASD. Importantly, the nutrient levels being examined in these studies are relevant to general clinical populations and represent suboptimal levels rather than severe deficiencies. These data suggest that moderate deficiencies in single nutrients can act as permissive factors for FASD, and that adequate nutritional status or intervention through supplementation may provide protection from some of the adverse effects of prenatal alcohol exposure.

Prenatal zinc deficiency: influence on heart morphology and distribution of key heart proteins in a rat model

The etiology of congenital heart disease is multifactorial, with genetics and nutritional deficiencies recognized as causative agents. Maternal zinc (Zn) deficiency is associated with an increased risk for fetal heart malformations; however, the contributing mechanisms have yet to be identified. In this study, we fed pregnant rats a Zn-adequate diet (ZnA), a Zn-deficient (ZnD), or a restricted amount of Zn adequate diet (RF) beginning on gestation day (GD) 4.5, to examine whether increased cell death and changes in cardiac neural crest cells (NCC) play a role in Zn deficiency-induced heart defects. Fetuses were collected on GD 13.5, 15.5, and 18.5 and processed for GATA-4, FOG-2, connexin-43 (Cx43), HNK-1, smooth muscle alpha-actin (SMA) and cleaved caspase-3 protein expression. Fetuses from ZnA-fed dams showed normal heart development, whereas fetuses from dams fed with the ZnD diet exhibited a variety of heart anomalies, particularly in the region of the outflow tract. HNK-1 expression was lower than normal in the hearts of GD13.5 and 15.5 ZnD fetuses, particularly in the right atrium and in the distal tip of the interventricular septum. Conversely, Cx43 immunoreactivity was increased throughout the heart in fetuses from ZnD dams compared to fetuses from control dams. The distribution and intensity of expression of SMA, GATA-4, FOG-2, and markers of apoptosis were similar among the three groups. We propose that Zn deficiency induced alterations in the distribution of Cx43 and HNK-1 in fetal hearts contribute to the occurrence of the developmental heart anomalies.

Zinc nutritional status modulates expression of ahr-responsive p450 enzymes in vascular endothelial cells

Zinc has anti-inflammatory properties and is crucial for the integrity of vascular endothelial cells, and the development and homeostasis of the cardiovascular system. The aryl hydrocarbon receptor (AhR) which is expressed in the vascular endothelium also plays an important role in responses to xenobiotic exposure and cardiovascular development. We hypothesize that cellular zinc can modulate induction of AhR responsive genes in endothelial cells. To determine if zinc deficiency can alter responses to AhR ligands, aortic endothelial cells were exposed to the AhR ligands 3,3',4,4'-tetrachlorobiphenyl (PCB77) or beta-naphthoflavone (beta-NF) alone or in combination with the membrane permeable zinc chelator TPEN, followed by measurements of the AhR responsive cytochrome P450 enzymes CYP1A1 and 1B1. Compared to vehicle treated cells, both PCB77-induced CYP1A1 activity (EROD) and mRNA expression were significantly reduced during zinc deficiency. In addition, PCB77 and beta-NF-mediated upregulation of CYP1A1 and CYP1B1 protein expression was significantly reduced in zinc-deficient endothelial cells. The inhibition of CYP1A1 and CYP1B1 protein expression caused by zinc deficiency was reversible by cellular zinc supplementation. Overall, our results strongly suggest that nutrition can modulate an environmental toxicant-induced biological outcome and that adequate levels of individual nutrients such as zinc are necessary for induction of AhR responsive genes in vascular endothelial cells.

Correlation between birth defects and dietary nutrition status in a high incidence area of China

OBJECTIVE

To investigate the association between birth defects and dietary nutrient intake in a high risk area of China.

METHODS

A dietary survey was performed and serum folic acid was measured in women whose pregnancy was affected by neural tube defects (NTDs) or unaffected by any birth defects (BDs) in Zhongyang and Jiaokou Counties in Shanxi Province of China.

RESULTS

The local average consumption of foods including dark green vegetables, fruits, fat and meat, and nutrient intake (e.g., energy, protein, retinol, riboflavin, vitamin E, and selenium) were lower than the national average level. In women of childbearing age, these regions, the intake of nutrients was much lower than the recommended nutrient intake (9%-77%). The case-control dietary nutrition study of women whose pregnancy was affected by BDs (including NTDs and congenital heart defects) demonstrated that, in early pregnancy, adequate nutrition (i.e., eating meat, fresh vegetables, fruit more than once a week) was a protective factor, while eating germinated potatoes was a risk factor. The geometrical mean (p5-p95) of serum folic acid in women with NTD birth defects was 9.6 nmol/L (3.6, 23.03), which was significantly lower than that in normal women (14.03 nmol/L).

CONCLUSION

Women of childbearing age in the two counties of Shanxi Province, China, have a marked insufficient intake of some nutrients, especially folic acid, zinc, vitamins A and B12. This nutrient deficiency may be an important risk factor for the high prevalence of birth defects in these regions. Therefore, adequate dietary nutrition in early pregnancy can prevent BDs.

Zinc dynamics in the myocardial redox signaling network

Zinc plays a vital role in various cellular functions. Zinc deprivation is associated with severe disorders related to growth, maturation, and stress responses. In the heart, zinc affects differentiation and regeneration of cardiac muscle, cardiac conductance, acute stress responses, and recovery of heart transplants. Recent discoveries of the molecular players in zinc homeostasis revealed that the amount of intracellular free zinc is tightly controlled on the level of uptake, intracellular sequestration, redistribution, storage, and elimination, consequently creating a narrow window of optimal zinc concentration in the cells. Most of intracellular zinc is bound to numerous structural and regulatory proteins, with metabolically active, labile zinc present in picoto nanomolar concentrations. The central position of zinc in the redox signaling network is built on its unique chemical nature. The redox inert zinc creates a redox active environment when it binds to a sulfur ligand. The reversible oxidation of the sulfur ligand is coupled to the reversible zinc release from the protein, thereby executing the task of so-called protein "redox zinc switch." Clearly, the impairment of zinc homeostasis will have far reaching physiological consequences.

Intracellular distributions of essential elements in cardiomyocytes

We describe the intracellular distributions of nine essential elements (P, S, Cl, K, Ca, Mn, Fe, Cu, and Zn) found in cardiomyocytes imaged using synchrotron X-ray induced fluorescence. Cardiomyocytes were isolated from rat hearts, flash frozen on Si(3)N(4) windows, freeze-dried, and imaged with approximately 300 nm spatial resolution. Distinct longitudinal patterns in cardiomyocytes were most apparent for the elements Fe and Cu, which clearly colocalized. Transverse striations were apparent for P, S, Fe, and Zn, while those for Zn were consistently the most prominent ( approximately 10(-3)M) and appeared with a periodicity in the range 1.63-1.75 microm, the expected length of a sarcomere. Transverse striations for high concentrations of P, Fe, and Zn and low concentrations of S colocalized and coincided with the I-band of the intact cardiomyocyte. Fluorescence microscopy using FluoZin-3 in intact cardiomyocytes suggests that Zn(2+) influx is through sarcolemmal calcium channels and that significant stores of intracellular Zn(2+) may be released quickly (<1s) into the cytosol. These data collectively suggest that Zn(2+) is buffered by structures associated near the T-tubules and/or in the sarcoplasmic reticulum and is found in relative abundance sufficient to act as a modifier of Ca(2+) regulation or as a possible signaling messenger for gene expression.

Zinc deficiency-induced cell death

Zinc deficiency is characterized by an attenuation of growth factor signaling pathways and an amplification of p53 pathways. This outcome is facilitated by hypo-phosphorylation of AKT and ERK secondary to zinc deficiency, which are permissive events to the activation of the intrinsic cell death pathway. Low zinc concentrations provide an environment that is also conducive to the production of reactive oxygen/reactive nitrogen species (ROS/RNS) and caspase activation. Additionally, during zinc deficiency endogenous survival pathways such as NF-kappaB are inhibited in their transactivation potential. The above factors contribute to the irreversible commitment of the zinc deficient cell to death.

Zinc, oxidant-triggered cell signaling, and human health

Zinc (Zn) deficiency, a frequent condition in human populations, induces oxidative stress and subsequently activates/inhibits oxidant-sensitive transcription factors that can affect cell function, proliferation and survival leading to disease. Zn deficiency-triggered oxidative stress could affect cell signaling, including: (1) transcription factors containing Zn finger motifs, and (2) other oxidant-sensitive transcription factors (NF-kappaB and AP-1). The Zn finger motif in the Zn finger transcription factors is mainly a DNA binding domain. Cysteine residues coordinate the Zn ion folding structural domains that participate in intermolecular interactions. Oxidative stress can impair the DNA-binding activity of Zn finger transcription factor, by oxidizing the cysteine residues and therefore altering the secondary structure of the protein. AP-1 is generally activated in Zn deficiency that can occur secondary to an increase in cellular H(2)O(2), followed by activation of MAPKs p38 and JNK. The role of AP-1 in Zn deficiency-associated pathology remains to be established. The cytosolic steps of the NF-kappaB cascade are activated by oxidants in Zn deficiency. However, an impaired nuclear transport of the active transcription factor leads to a low expression of NF-kappaB-dependent genes that could be involved in multiple aspects of Zn deficiency associated pathology. In summary, Zn deficiency induces oxidative stress that can both, lead to tissue oxidative damage and/or to the modulation of select signaling cascades. Their role in the pathology of Zn deficiency remains to be defined.