Phosphorylation status of matrix metalloproteinase 2 in myocardial ischaemia-reperfusion injury.

Objective: To investigate whether alterations in the phosphorylation status of matrix metalloproteinase 2 (MMP-2) in the heart may be protective in the setting of ischaemia-reperfusion (IR) injury.

Design: In-vitro heart function and biochemical research study.

Setting: University basic science laboratory.

Regulation of lysophosphatidate signaling by autotaxin and lipid phosphate phosphatases with respect to tumor progression, angiogenesis, metastasis and chemo-resistance.

Evidence from clinical, animal and cell culture studies demonstrates that increased autotaxin (ATX) expression is responsible for enhancing tumor progression, cell migration, metastases, angiogenesis and chemo-resistance. These effects depend mainly on the rapid formation of lysophosphatidate (LPA) by ATX. Circulating LPA has a half-life of about 3 min in mice and it is degraded by the ecto-activities of lipid phosphate phosphatases (LPPs).

Antioxidant treatment protects diabetic rats from cardiac dysfunction by preserving contractile protein targets of oxidative stress.

Background: Animal studies suggest that reactive oxygen species (ROS) play an important role in the development of diabetic cardiomyopathy.

Hypothesis: Matrix metalloproteinase-2 (MMP-2) is activated by ROS and contributes to the acute loss of myocardial contractile function by targeting and cleaving susceptible proteins including troponin I (TnI) and alpha-actinin.

Methods: Using the streptozotocin-induced diabetic rat model, we evaluated the effect of daily in vivo administration of sodium selenate (0.

Phosphatidate degradation: phosphatidate phosphatases (lipins) and lipid phosphate phosphatases.

Three lipid phosphate phosphatases (LPPs) regulate cell signaling by modifying the concentrations of a variety of lipid phosphates versus their dephosphorylated products. In particular, the LPPs are normally considered to regulate signaling by the phospholipase D (PLD) pathway by converting phosphatidate (PA) to diacylglycerol (DAG). LPP activities do modulate the accumulations of PA and DAG following PLD activation, but this could also involve an effect upstream of PLD activation.

The PPARgamma agonist rosiglitazone enhances rat brown adipose tissue lipogenesis from glucose without altering glucose uptake.

We investigated the mechanisms whereby peroxisome proliferator-activated receptor-gamma (PPARgamma) agonism affects glucose and lipid metabolism in brown adipose tissue (BAT) by studying the impact of PPARgamma activation on BAT glucose uptake and metabolism, lipogenesis, and mRNA levels plus activities of enzymes involved in triacylglycerol (TAG) synthesis. Interscapular BAT of rats treated or not with rosiglitazone (15 mg*kg(-1).day(-1), 7 days) was evaluated in vivo for glucose uptake and lipogenesis and in vitro for glucose metabolism, gene expression, and activities of glycerolphosphate acyltransferase (GPAT), phosphatidate phosphatase-1 (PAP or lipin-1), and diacylglycerol acyltransferase (DGAT).

Depot-specific effects of the PPARgamma agonist rosiglitazone on adipose tissue glucose uptake and metabolism.

We investigated mechanisms whereby peroxisome proliferator-activated receptor gamma (PPARgamma) agonism redistributes lipid from visceral (VF) toward subcutaneous fat (SF) by studying the impact of PPARgamma activation on VF and SF glucose uptake and metabolism, lipogenesis, and enzymes involved in triacylglycerol (TAG) synthesis. VF (retroperitoneal) and SF (inguinal) of rats treated or not for 7 days with rosiglitazone (15 mg/kg/day) were evaluated in vivo for glucose uptake and lipogenesis and in vitro for glucose metabolism, gene expression, and activities of glycerolphosphate acyltransferase (GPAT), phosphatidate phosphatase-1 (or lipin-1), and diacylglycerol acyltransferase. Rosiglitazone increased SF glucose uptake, GLUT4 mRNA, and insulin-stimulated glucose oxidation, conversion to lactate, glycogen, and the glycerol and fatty acid components of TAG.

Protective action of doxycycline against diabetic cardiomyopathy in rats.

Background And Purpose: Reactive oxygen and nitrogen species play an important role in the development of diabetic cardiomyopathy. They can activate matrix metalloproteinases (MMPs), and MMP-2 in particular is known to mediate early consequences of oxidative stress injury in the heart. Therefore, we investigated the role of MMP-2 and the effect of the MMP inhibitor doxycycline on the changes of heart function caused by diabetes.

The level and compartmentalization of phosphatidate phosphatase-1 (lipin-1) control the assembly and secretion of hepatic VLDL.

Phosphatidate phosphatase-1 (PAP-1) converts phosphatidate to diacylglycerol and plays a key role in the biosynthesis of phospholipids and triacylglycerol (TAG). PAP-1 activity is encoded by members of the lipin family, including lipin-1 (1alpha and 1beta), -2, and -3. We determined the effect of lipin-1 expression on the assembly and secretion of very low density lipoproteins (VLDL) using McA-RH7777 cells.

Glucocorticoids and cyclic AMP selectively increase hepatic lipin-1 expression, and insulin acts antagonistically.

Glucocorticoids (GCs) increase hepatic phosphatidate phosphatase (PAP1) activity. This is important in enhancing the liver's capacity for storing fatty acids as triacylglycerols (TAGs) that can be used subsequently for beta-oxidation or VLDL secretion. PAP1 catalyzes the conversion of phosphatidate to diacylglycerol, a key substrate for TAG and phospholipid biosynthesis.

Regulation of matrix metalloproteinase-2 (MMP-2) activity by phosphorylation.

The regulation of matrix metalloproteinases (MMP) has been studied extensively due to the fundamental roles these zinc-endopeptidases play in diverse physiological and pathological processes. However, phosphorylation has not previously been considered as a potential modulator of MMP activity. The ubiquitously expressed MMP-2 contains 29 potential phosphorylation sites.

Temporal variation of oxidant stress in critically ill patients.

Aim: Our aim was to investigate indicators of lipid peroxidation via observing temporal changes or daily fluctuations in cytoprotective enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and serum components possessing antioxidant activity against free radicals and malondialdehyde (MDA) such as uric acid. This study was conducted in a small number of critically ill patients versus healthy volunteers in order to design an effective antioxidant therapy regimen under oxidative stress.

Methods: Six critically ill patients and 6 young healthy volunteers were recruited.

Three mammalian lipins act as phosphatidate phosphatases with distinct tissue expression patterns.

We previously identified mutations in the Lpin1 gene, encoding lipin-1, as the underlying cause of lipodystrophy in the fatty liver dystrophy (fld) mutant mouse. Lipin-1 is normally expressed at high levels in adipose tissue and skeletal muscle, and deficiency in the fld mouse causes impaired adipose tissue development, insulin resistance, and altered energy expenditure. We also identified two additional lipin protein family members of unknown function, lipin-2 and lipin-3.

The role of matrix metalloproteinase inhibitors in ischemia-reperfusion injury in the liver.

Liver ischemia-reperfusion injury is characterized by cell necrosis and apoptosis and by profound modifications in the extracellular matrix (ECM). During the complex series of events that take place both during ischemia and when normal blood flow is restored (reperfusion), a concerted regulation of release and activation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) mainly by stellate cells, Kupffer cells and inflammatory cells leads first to endothelial cell injury and subsequent infiltration of neutrophils into the wounded area. Later, MMP activation causes degradation of extracellular matrix components of the liver, mainly collagen and fibronectin, altering tissue architecture.

Degradation of myosin light chain in isolated rat hearts subjected to ischemia-reperfusion injury: a new intracellular target for matrix metalloproteinase-2.

Background: Matrix metalloproteinase-2 (MMP-2) contributes to cardiac dysfunction resulting from ischemia-reperfusion (I/R) injury. MMP-2 not only remodels the extracellular matrix but also acts intracellularly in I/R by degrading troponin I. Whether other intracellular targets exist for MMP-2 during I/R is unknown.

Matrix metalloproteinase-2 (MMP-2) is present in the nucleus of cardiac myocytes and is capable of cleaving poly (ADP-ribose) polymerase (PARP) in vitro.

Matrix metalloproteinases (MMPs) are traditionally known for their role in extracellular matrix remodeling. Increasing evidence reveals several alternative substrates and novel biological roles for these proteases. Recent evidence showed the intracellular localization of MMP-2 within cardiac myocytes, colocalized with troponin I within myofilaments.

Evaluation of the antioxidant effect of melatonin by flow injection analysis-luminol chemiluminescence.

The antioxidant effect of melatonin was evaluated by using a flow injection analysis chemiluminescence (FIA-CL) method to measure alone its direct antioxidant behaviour in aqueous solutions. Inhibition by melatonin, DL-tryptophan or serotonin (5-hydroxytryptamine, 5-HT) of the steady CL emissions of various oxidants with luminol was measured. LogIC(50) values of melatonin were calculated: -2.

Enhancement of luminol chemiluminescence by cysteine and glutathione.

Cysteine enhancement of cobalt(II)-catalysed chemiluminescence of hydrogen peroxide and luminol occurs in carbonate buffer (but not in borate buffer), whether cysteine mixes with hydrogen peroxide before it mixes with luminol-cobalt(II) or vice versa. Enhancement was measured by the ratio of the signals in the presence and absence of cysteine; standard errors were generally < 5% of the mean ratio. Cystine in sufficiently acidic solution also enhances the chemiluminescence but otherwise diminishes the emission.

Does prevention of free radical reactions influence digoxin-arrhythmias?

In the present study, the possible role of oxygen-derived free radicals (OFR) on digoxin- (0.6 mg/kg(-1) IV bolus) induced arrhythmias of anesthetized guinea-pigs has been investigated. Guinea-pigs (300400 g) of either sex were anesthetized with urethane (1.

Effects of WEB 2086 on the protective role of preconditioning against arrhythmias in rats.

The purpose of the present study was to investigate a possible role of platelet activating factor (PAF) in ischaemic preconditioning (PC). Since both PC and PAF act through protein kinase C (PKC), PAF could play a role in PC. To test this hypothesis, anaesthetized, open-chest male rats were subjected to four different protocols.