Short-term magnesium deficiency upregulates sphingomyelin synthase and p53 in cardiovascular tissues and cells: relevance to the de novo synthesis of ceramide

Magnesium Supplementation Affects the Expression of Sirtuin1, Tumor Protein P53 and Endothelial Nitric Oxide Synthase Genes in Patients with Atherosclerosis: A Double-Blind, Randomized, Placebo-Controlled Trial

Magnesium seems to play a role in improving cardiovascular function, but its exact mechanism is unknown. In this study, we hypothesized that magnesium could modulate the expression of genes involved in atherosclerosis. The aim of the present investigation was to evaluate the effect of magnesium sulfate on the expression of sirtuin1 (SIRT1), tumor protein p53 (TP53), and endothelial nitric oxide synthase (eNOS) genes in patients with atherosclerosis. This study was a placebo-controlled double-blind randomized clinical trial on 56 patients with angiographically proven atherosclerosis. Participants were randomly divided into two groups receiving 300 mg/day magnesium sulfate (n = 29) and placebo (n = 27) for three months (following up every month). Fasting blood samples were taken before and after the intervention and total RNA was extracted and used to evaluate the expression level of SIRT1, TP53, and eNOS genes by Real-Time PCR. The expression of eNOS gene was significantly increased (P < 0.0001) and the expression of TP53 gene was decreased (P = 0.02) in the magnesium sulfate group compared to the placebo group. But SIRT1 gene expression was not significantly different between the two groups. Our findings demonstrate that magnesium sulfate supplementation may have a protective role against the progression of atherosclerosis through upregulation of eNOS and downregulation of TP53 gene. Trial registration: This present clinical trial has been registered in the Iranian Registry of Clinical Trials (IRCT) with the registration code of "IRCT20151028024756N3", https://www.irct.ir/trial/29097?revision=114102. Registered on 16 December 2019.

Potential Drug Targets for Ceramide Metabolism in Cardiovascular Disease

Cardiovascular disease poses a significant threat to the quality of human life. Metabolic abnormalities caused by excessive caloric intake have been shown to lead to the development of cardiovascular diseases. Ceramides are structural molecules found in biological membranes; they are crucial for cell survival and lipid metabolism, as they maintain barrier function and membrane fluidity. Increasing evidence has demonstrated that ceramide has a strong correlation with cardiovascular disease progression. Nevertheless, it remains a challenge to develop sphingolipids as therapeutic targets to improve the prognosis of cardiovascular diseases. In this review, we summarize the three synthesis pathways of ceramide and other intermediates that are important in ceramide metabolism. Furthermore, mechanistic studies and therapeutic strategies, including clinical drugs and bioactive molecules based on these intermediates, are discussed.

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles loaded with miR-223 ameliorate myocardial infarction through P53/S100A9 axis

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been proposed as a promising strategy for myocardial infarction (MI). This study aims to explore the mechanism of human umbilical cord MSCs (hucMSCs)-derived EVs loaded with miR-223 on MI. Inflammation, cell biological functions, and fibrosis in vitro were measured. Furthermore, MI rat models were established to verify the role of EVs-miR-223 in vivo. The binding relationship between miR-223 and P53 was confirmed. ChIP assay was utilized to observe the combination of P53 and S100A9. The suppressed fibrosis of cardiomyocytes occurred with cells overexpressing miR-223. MiR-223 contributed to the angiogenesis of HUVECs. P53 was a target gene of miR-223. In vivo, miR-223 relieved myocardial fibrosis and inflammation infiltration, and promoted the angiogenesis in MI rats. HucMSC-derived EVs loaded with miR-223 mitigates MI and promotes myocardial repair through the P53/S100A9 axis, manifesting the underlying therapy values of hucMSC-derived EVs loaded with miR-223 in MI.

Dietary Folic Acid Alters Metabolism of Multiple Vitamins in a CerS6- and Sex-Dependent Manner

Folic acid, an oxidized synthetic pro-vitamin B₉, is widely used in vitamin supplement formulations and food fortification to maintain optimal folate status in humans. Studies on folic acid (FA) efficiency in improving folate status and correcting folate deficiency pathologies are abundant, but precise knowledge of FA effects on human and animal tissues is not available. In our recent study, 10-week-old wild-type and CerS6 knockout (KO) mice were placed on FA-deficient, control, or FA over-supplemented diet for 4 weeks. Untargeted metabolomics characterization of mouse liver, brain, and testes tissues after the dietary treatment revealed profound effects of FA on the liver metabolome. Here, we present the analysis of dietary FA effects on tissue concentrations of other vitamins in mice. Despite the expectation that identical dietary supply of the vitamins (excluding FA) to each group should support similar tissue vitamins concentrations, metabolomics data demonstrate significant alterations of tissue concentrations of multiple vitamins by different levels of FA supplementation that were sex- and genotype-dependent. Moreover, we found significant differences in the liver concentration of retinol, thiamin diphosphate, pantetheine, pyridoxal, and pyridoxamine between males and females. While the liver had more changes in vitamins and vitamin derivative levels, the brain tissue and testes also showed changes linked to FA supplementation. Over-supplementation with FA had negative effects on concentrations of vitamins A, B₁, B₂, and B₆, or their metabolites in the liver, but increased intermediates in coenzyme A (CoA) biosynthesis, as well as gamma/beta-tocopherol and phosphorylated forms of B₆ in the CerS6 KO brain. Overall, our data demonstrate that dietary FA supplementation significantly affects the metabolism of other vitamins, and that these effects depend on the CerS6 status and sex of the animal. Further research is required to determine whether the observed effects are specific to FA, and the mechanisms that are involved.

Extracellular and Intracellular Magnesium Deficiency Found in Pregnant Women with Preeclampsia and Gestational Diabetes Is Associated with Overexpression of Notch Proteins, Cytokines, p53, NF-kB and Proto-Oncogenes: Potential Importance in Growth Retardation, Stillbirths, Fetal Mutations and Increased Cardiovascular Risks and Stroke with Advancing Age in Pregnant Women

In 1983, three of us reported in “Science” that umbilical-placental arteries and veins, obtained from normal pregnant women at term delivery, when exposed in vitro to low concentrations of Mg2+ went into vasospasm; the lower the Mg2+, the greater the contractile force developed. These blood vessels also demonstrated amplified contractile force development when challenged with circulating amines and peptides (e.g., norepinephrine, 5-HT, angiotensin II, etc.). We suggested that severe Mg deficiency during pregnancy could in part be responsible for spontaneous abortions, loss of fetuses, stillbirths, and developmental alterations in infants. Using short-term dietary Mg deficient animals, we have noted a great many molecular and biochemical alterations in ventricular, atrial and somatic vascular smooth muscle alterations including DNA methylation and histone changes leading us to speculate that Mg deficiency may represent a genotoxin promoting mutations and causing epigenetic changes. Over the last 35 years, we have new data on severely preeclamptic and gestational diabetic pregnant women that gives credence to our original hypothesis and demonstrates that recently- discovered developmental proteins, originally found 100 years ago in Drosophila fruit flies termed the “Notch pathway”, due to effects on its wings, appears to be important in development of the umbilical-placental blood vessels in pregnant women. Along with the developmental molecule, p53, these Notch proteins clearly alter the behavior of the umbilical-placental vessels. We believe these new findings probably help to explain many of the genetic-toxicity effects seen in women later in life who develop strokes and cardiovascular diseases. Notch alterations could also play an important role in babies born with cardiac defects.

Role of Cellular Magnesium in Human Diseases

Magnesium is required for many of the major organs to function and plays a crucial role in human and mammalian physiology. Magnesium is essential for the structure of bones and teeth, acts as a cofactor for more than 300 enzymes in the body, including binding to ATP for kinase reactions, and affects permeability of excitable membranes and neuromuscular transmission. Despite these essential roles, much is still unknown about magnesium physiology and homeostasis. Currently, nutritionists believe that the general population intakes insufficient magnesium daily through the diet. The effects of magnesium deficiency are, for the most part undetected, and simple, widespread assessments of magnesium intake remain unavailable for humans. Many of the patients admitted to hospitals or medical care facilities are unaware of their low magnesium levels. Moreover, because magnesium is predominantly an intracellular cation (>99%), serum magnesium levels remain a poor predictor of tissue magnesium content and availability. This review will discuss the effects of magnesium deficiency in various pathologies affecting the human population. The underlying causes for magnesium depletion in major physiological systems will be examined along with the involved signaling pathways and the main roles of magnesium homeostasis. Where possible (e.g. alcoholism), the implications of administering supplemental magnesium will be discussed. Ultimately, this review will advocate for the necessity of identifying easy and reproducible methods to assess serum and cellular magnesium levels and to identify magnesium deficiency in order to alleviate related pathological conditions.

The high heart health value of drinking-water magnesium

Universal drinking water and beverages containing moderate to high levels of magnesium (10–100 ppm) could potentially prevent 4.5 million heart disease and stroke deaths per year, worldwide. This potential is calculated with 2010 global mortality figures combined with a recent quantification of water-magnesium’s inverse association with heart disease and stroke mortality. The modern processed food diet, low in magnesium and spreading globally, makes this well-researched potential of drinking-water magnesium worth serious consideration, especially in areas where insufficient dietary intake of magnesium is prevalent.

Short-term magnesium deficiency downregulates telomerase, upregulates neutral sphingomyelinase and induces oxidative DNA damage in cardiovascular tissues: relevance to atherogenesis, cardiovascular diseases and aging

1) short-term dietary deficiency of magnesium (Mg; 21 days) in rats (MgD) would result in a downregulation of telomerase in cardiac and aortic smooth muscle cells, 2) low levels of Mg(2+) added to drinking water (DW) would either prevent or greatly reduce the downregulation of telomerase in MgD, 3) MgD in rats would cause an upregulation of neutral-sphingomyelinase (N-SMAse) and p53, 4) short-term MgD would result in oxidation of DNA in diverse cardiac muscle and aortic smooth muscle cells as exemplified by measurement of 8-hydroxydeoxyguanosine (8-OH-dG), and 5) cross-talk between telomerase, N-SMase, p53, and 8-OH-dG would be evident in left ventricular (LV), right ventricular (RV), atrial and aortic smooth muscle obtained from rats subjected to short-term MgD. The data indicated that short-term MgD (10% normal dietary intake) resulted in downregulation of telomerase in LV, RV, atrial and aortic muscle cells; even very low levels of water-bourne Mg(2+) (e.g., 15-40 mg/lday) either prevented or ameliorated the downregulation of telomerase. Our experiments also showed that MgD resulted in a 7-10 fold increased formation of 8-OH-dG in the cardiac and aortic muscle cells. The experiments also confirmed that short-term dietary deficiency of Mg resulted in greatly increased upregulation of N-SMAse and p53 in the cardiac and aortic muscle tissues. These new experiments point to a sizeable cross-talk among telomerase, N-SMAse, and p53 in rat cardiac and peripheral vascular muscle exposed to a short-term MgD. These studies would be compatible with the idea that even short-term MgD could cause alterations of the genome in diverse cell types leading to mutations of cardiac, vascular, and endothelial cells seen in aging and atherogenesis. Since we have shown, previously, that activation of N-SMAse in MgD leads to synthesis and release of ceramide in cardiovascular tissues and cells, we believe this pathway, most likely, helps to result in downregulation of telomerase, upregulation of transcription factors (e.g., p53; NF-kB), cytokine release, mutations, transformations, and dysfunctional growth seen in the cardiac and vascular cells observed in the normal aging process, atherogenesis, hypertension, and cardiac failure. Lastly, we suggest ways in which this hypothesis can be tested.

Short-term Mg deficiency upregulates protein kinase C isoforms in cardiovascular tissues and cells; relation to NF-kB, cytokines, ceramide salvage sphingolipid pathway and PKC-zeta: hypothesis and review

Numerous recent,epidemiological studies reveal that Western populations are growing more and more deficient in daily Mg intake which have been linked to etiology of cardiovascular (CV) diseases. A growing body of evidence suggests that a major missing link to this dilemma may reside within the sphingolipid-ceramide pathways. For the past 25 years , our labs have been focusing on these pathways in Mg-deficient mammals. The objective of this paper is two-fold: 1) to test various hypotheses and 2) to review the current status of the field and how protein kinase C isoforms may be pivotal to solving some of the CV attributes of Mg deficiency. Below, we test the hypotheses that: 1) short-term dietary deficiency of magnesium (MgD) would result in the upregulation of protein kinase C (PKC) isoforms in left ventricular (LV) and aortic smooth muscle (ASM) and serum; 2) MgD would result in a release of select cytokines and an upregulation of NF-kB in LV and ASM, and in primary cultured aortic smooth muscle cells (PCASMC); 3) MgD would result in an activation of the sphingolipid salvage pathway in LV and ASM, and in PCASMC; 4) MgD would result in a synthesis of sphingosine, but not sphinganine, in PCASMC which could be inhibited by fumonisin B1 (FB) an inhibitor of ceramide synthase (CS), but not scyphostatin an inhibitor of neutral sphingomyelinase (N-SMase); 5) incubation of PCASMC (in low Mg(2+)) with the PKC-mimic PMA would result in release and synthesis of NF-kB, cytokines, and ceramide but not sphingosine. The new data indicate that short-term MgD (10% normal dietary intake) result in an upregulation of all three classes of PKC isoforms in LV, aortic muscle and in serum coupled to the upregulation of ceramide, NF-kB activation, and cytokines. High degrees of linear correlation were found to exist between upregulation of PKC isoforms, p65 and cytokine release, suggesting cross-talk between these molecules and molecular pathways. Our experiments with PCASMCs demonstrated that MgD caused a pronounced synthesis of sphingosine (but not sphinganine), which could be inhibited with fumonisin B1, but not by scyphostatin; use of PMA stimulation released ceramide but not sphingosine suggesting a role for the "sphingolipid salvage pathway" in MgD vascular muscle. Use of different PKC pharmacological inhibitors suggested that although all three classes of PKC molecules, i.e., classical, novel, and atypical, play roles in MgD-induced synthesis/release of ceramide, sphingosine, and cytokines as well as activation of NF-kB, to varying degrees, PKC-zeta appears to play a greater role in these events than any of the other PKC isoforms; a specific PKC-zeta inhibitory peptide inhibited formation of sphingosine. Even low levels of water-borne Mg (e.g., 15 mg/l/day) either prevented or ameliorated the upregulation of all three classes of PKC isoforms. An attempt is made to integrate our new data with previous information in order to possibly explain many of the cardiovascular effects of MgD.

Magnesium deficiency upregulates sphingomyelinases in cardiovascular tissues and cells: cross-talk among proto-oncogenes, Mg(2+), NF-κB and ceramide and their potential relationships to resistant hypertension, atherogenesis and cardiac failure

The present study tested the hypotheses that 1) short-term (ST) dietary deficiency of magnesium (MgD; 21 days) in rats would result in the upregulation of neutral-, acid-, and alkaline- sphingomyelinases SMases) in cardiac and vascular smooth muscles (VSMCs), 2) ST MgD would result in an upregulation of proto-oncogenes, i.e., c-Fos and c-Jun, as well as the p65 and c-Rel components of NF-κB in cardiac and VSMCs, 3) low levels of Mg(2+) added to drinking water would either prevent or greatly reduce the upregulation of the SMases and proto-oncogene expression, 4) exposure of primary cultured VSMCs to low extracellular Mg(2+) concentration would lead to release of ceramide in both cerebral and aortic VSMCs, 5) specific inhibitors of neutral- and acid-SMAs would reduce the release of ceramide in cultured VSMCs exposed to low extracellular Mg(2+), and 6) specific inhibitors of neutral- and acid-SMases would lead to reductions in the expression of c-fos, c-Jun, and NF-κB components. The data indicate that neutral-, acid-and alkaline-SMases exist in rat cardiac and VSMCs. ST MgD resulted in over 150% increases in SMase activity and proto-oncogene expression in left and right ventricular muscle, atrial muscle, and abdominal aortic smooth muscle; even very low levels of Mg(2+) added to drinking water either prevented or ameliorated the activation of all 3-SMases as well as expression of c-Fos and c-Jun; scyphostatin and desipramine reduced the low Mg(2+) - induced expression of the proto-oncogenes as well as p65 and c-Rel in VSMCs. Exposure of the VSMCs to low Mg(2+) resulted in more than a 100% increase in release of ceramide; scyphostatin and desipramine reduced greatly the release of ceramide from the VSMCs. We believe when the present data are viewed in light of our previous, recent findings on the effects of Mg deficiency on most of the major enzymes in the sphingomyelin-ceramide pathway, that they could provide a rational basis for the treatment and prevention of drug-resistant hypertension, atherogenesis, and difficult-to-treat forms of cardiac failure.

p53 and Ceramide as Collaborators in the Stress Response

The sphingolipid ceramide mediates various cellular processes in response to several extracellular stimuli. Some genotoxic stresses are able to induce p53-dependent ceramide accumulation leading to cell death. However, in other cases, in the absence of the tumor suppressor protein p53, apoptosis proceeds partly due to the activity of this "tumor suppressor lipid", ceramide. In the current review, we describe ceramide and its roles in signaling pathways such as cell cycle arrest, hypoxia, hyperoxia, cell death, and cancer. In a specific manner, we are elaborating on the role of ceramide in mitochondrial apoptotic cell death signaling. Furthermore, after highlighting the role and mechanism of action of p53 in apoptosis, we review the association of ceramide and p53 with respect to apoptosis. Strikingly, the hypothesis for a direct interaction between ceramide and p53 is less favored. Recent data suggest that ceramide can act either upstream or downstream of p53 protein through posttranscriptional regulation or through many potential mediators, respectively.

Development of an enzymatic assay for sphingomyelin with rapid and automatable performances: Analysis in healthy subjects and coronary heart disease patients

BACKGROUND

Sphingomyelin (SM) is an important choline group-containing phospholipid and is considered to be an independent risk factor for coronary heart disease.

METHODS

We have developed a specific enzymatic assay for SM measurement with rapid and automatable performances by using two-reagent system involving sphingomyelinase. We performed within-run and between-run precision, linearity test, detection limit, recovery test and interference to validate this assay. Then, we measured the serum SM concentration in 194 healthy subjects and 141 consecutive patients undergoing coronary angiography.

RESULTS

The within-run and between-run coefficients of variation for SM concentrations were 1.1-1.3% and 1.0-1.2%, respectively. Quantitative measurements to a lower limit of 30 μmol/L were shown to be possible. The recoveries of the exogenously added SM to the control samples were 98.7%-101.5%. No effect was observed after the addition of some interference materials. The mean ± SD of the serum SM concentration in the 194 healthy subjects was 553.3 ± 100.1 μmol/L. We found that the SM concentration was significantly higher among an acute coronary syndrome subjects than among the healthy subjects (P<0.01) and that the serum SM concentrations were significantly correlated with the serum magnesium concentration.

CONCLUSIONS

We have developed a rapid and automatable enzymatic assay for SM that enables the automatic measurement of choline-containing phospholipids. This assay may be useful for various types of biochemical and clinical research.

Short-term magnesium deficiency upregulates ceramide synthase in cardiovascular tissues and cells: cross-talk among cytokines, Mg2+, NF-κB, and de novo ceramide

The present study tested the hypotheses that 1) short-term dietary deficiency (MgD) of magnesium (21 days) would result in the upregulation of ceramide synthase (CS) in left ventricular (LV), right ventricular, atrial, and aortic smooth muscle, as well as induce a synthesis/release of select cytokines and chemokines into the LV and aortic smooth muscle and serum; 2) exposure of primary cultured vascular smooth muscle cells (VSMCs) to low extracellular Mg concentration would lead to the synthesis/release of select cytokines/chemokines, activation of N-SMase, and the de novo synthesis of ceramide; and 3) inhibition of CS by fumonisin B1 (FB1) or inhibition of neutral sphingomyelinase (N-SMase) by scyphostatin (SCY) in VSMCs exposed to low Mg would result in reductions in the levels of the cytokines/chemokines and lowered levels of ceramide concomitant with inhibition of NF-κB activation. The data indicated that short-term MgD (10% normal dietary intake) resulted in the upregulation of CS in ventricular, atrial, and aortic smooth muscles coupled to the synthesis/release of 12 different cytokines/chemokines, as well as activation of NF-κB in the LV and aortic smooth muscle and sera; even very low levels of water-borne Mg (e.g., 15 mg·l−1·day−1) either prevented or ameliorated the upregulation and synthesis of the cytokines/chemokines. Our experiments also showed that VSMCs exposed to low extracellular Mg resulted in the synthesis of 5 different cytokines and chemokines concomitant with synthesis/release of ceramide. However, inhibition of the synthesis and release of ceramide by either FB1 or SCY attenuated, markedly , the generation of ceramide, release of the cytokines/chemokines, and activation of NF-κB (as measured by activated p65 and cRel).

Mg deficiency results in modulation of serum lipids, glutathione, and NO synthase isozyme activation in cardiovascular tissues: relevance to de novo synthesis of ceramide, serum Mg and atherogenesis

The present work tested the hypothesis that short-term (S-T) dietary deficiency of magnesium (Mg) (21 days) in rats would: 1) result in reduction in serum(s) sphingomyelin (SM) and changes in several blood lipids, HDL-cholesterol (HDL-C) and phosphatidylcholine (PC) concomitant with elevations in s cholesterol (chol), s LDL+VLDL and trigycerides (TG), as well as reduction in the PC/cholesterol ratio; 2) lead to oxidative stress, characterized by reductions in glutathione (glut) content in the various chambers of the heart and activation of e-NOS and n-NOS in the atria, ventricles and aortic smooth muscle (ASM); 3) produce early cardiac damage characterized by leakage of creatine kinase (CK) and lactic dehydrogenase (LDH); and 4) demonstrate that these pathophysiological changes are a result of profound reductions in s ionized Mg (Mg(2+)) and activation of the SM-ceramide pathway. In addition, we hypothesized that: 1) exposure of primary cultured vascular smooth muscle cells (VSMCs) to low extracellular Mg(2+) would lead to de novo synthesis of ceramide and activation of NO synthase with reduction in glut, both of which would be attenuated by inhibition of sphingomyelinase (SMase) and serine palmitoyl CoA transferase (SPT); and 2) low levels of Mg(2+)added to the drinking water would either prevent or ameliorate these manifestations. Our data indicate that S-T Mg deficiency resulted in reductions in s Mg(2+), SM, PC, HDL-C and the PC/chol ratio concomitant with decreases in tissue levels of glut, leakage of cardiac CK and LDH, as well as activation of e-NOS and n-NOS in all chambers of the heart and ASM. The greater the reduction in s Mg(2+), the greater the effects on all parameters analyzed; very significant correlations to levels of s SM and Mg(2+) were found with all of the serum and tissue biochemical -molecular analytes measured. Our experiments also showed that VSMCs exposed to low Mg(2+)resulted in activation of NO synthase, loss of glut and de novo synthesis of ceramide which were attenuated by inhibitors of SMase and SPT. Low levels of drinking water Mg(2+)(e.g., 15 ppm) were cardio- and vascular protective. We believe these new findings support our concept of an important role for the SM-ceramide pathway in the manifestations of Mg deficiency and atherogenesis.