A key role of TRPC channels in the regulation of electromechanical activity of the developing heart.

Aims It is well established that dysfunction of voltage-dependent ion channels results in arrhythmias and conduction disturbances in the foetal and adult heart. However, the involvement of voltage-insensitive cationic TRPC (transient receptor potential canonical) channels remains unclear. We assessed the hypothesis that TRPC channels play a crucial role in the spontaneous activity of the developing heart.Methods and results TRPC isoforms were investigated in isolated hearts obtained from 4-day-old chick embryos. Using RT-PCR, western blotting and co-immunoprecipitation, we report for the first time that TRPC1, 3, 4, 5, 6, and 7 isoforms are expressed at the mRNA and protein levels and that they can form a macromolecular complex with the alpha 1C subunit of the L-type voltage-gated calcium channel (Cav1.2) in atria and ventricle. Using ex vivo electrocardiograms, electrograms of isolated atria and ventricle and ventricular mechanograms, we found that inhibition of TRPC channels by SKF-96365 leads to negative chrono-, dromo-, and inotropic effects, prolongs the QT interval, and provokes first-and second-degree atrioventricular blocks. Pyr3, a specific antagonist of TRPC3, affected essentially atrioventricular conduction. On the other hand, specific blockade of the L-type calcium channel with nifedipine rapidly stopped ventricular contractile activity without affecting rhythmic electrical activity.Conclusions These results give new insights into the key role that TRPC channels, via interaction with the Cav1.2 channel, play in regulation of cardiac pacemaking, conduction, ventricular activity, and contractility during cardiogenesis.

Targeting aquaporin function: potent inhibition of aquaglyceroporin-3 by a gold-based compound.

Aquaporins (AQPs) are membrane channels that conduct water and small solutes such as glycerol and are involved in many physiological functions. Aquaporin-based modulator drugs are predicted to be of broad potential utility in the treatment of several diseases. Until today few AQP inhibitors have been described as suitable candidates for clinical development. Here we report on the potent inhibition of AQP3 channels by gold(III) complexes screened on human red blood cells (hRBC) and AQP3-transfected PC12 cells by a stopped-flow method. Among the various metal compounds tested, Auphen is the most active on AQP3 (IC(50) = 0.8±0.08 µM in hRBC). Interestingly, the compound poorly affects the water permeability of AQP1. The mechanism of gold inhibition is related to the ability of Au(III) to interact with sulphydryls groups of proteins such as the thiolates of cysteine residues. Additional DFT and modeling studies on possible gold compound/AQP adducts provide a tentative description of the system at a molecular level. The mapping of the periplasmic surface of an homology model of human AQP3 evidenced the thiol group of Cys40 as a likely candidate for binding to gold(III) complexes. Moreover, the investigation of non-covalent binding of Au complexes by docking approaches revealed their preferential binding to AQP3 with respect to AQP1. The high selectivity and low concentration dependent inhibitory effect of Auphen (in the nanomolar range) together with its high water solubility makes the compound a suitable drug lead for future in vivo studies. These results may present novel metal-based scaffolds for AQP drug development.

Proteolytic activity in the adult and larval stages of the human roundworm parasite Angiostrongylus costaricensis

Angiostrongylus costaricensis is a nematode that causes abdominal angiostrongyliasis, a widespread human parasitism in Latin America. This study aimed to characterize the protease profiles of different developmental stages of this helminth. First-stage larvae (L1) were obtained from the faeces of infected Sigmodon hispidus rodents and third-stage larvae (L3) were collected from mollusks Biomphalaria glabrata previously infected with L1. Adult worms were recovered from rodent mesenteric arteries. Protein extraction was performed after repeated freeze-thaw cycles followed by maceration of the nematodes in 40 mM Tris base. Proteolysis of gelatin was observed by zymography and found only in the larval stages. In L3, the gelatinolytic activity was effectively inhibited by orthophenanthroline, indicating the involvement of metalloproteases. The mechanistic class of the gelatinases from L1 could not be precisely determined using traditional class-specific inhibitors. Adult worm extracts were able to hydrolyze haemoglobin in solution, although no activity was observed by zymography. This haemoglobinolytic activity was ascribed to aspartic proteases following its effective inhibition by pepstatin, which also inhibited the haemoglobinolytic activity of L1 and L3 extracts. The characterization of protease expression throughout the A. costaricensis life cycle may reveal key factors influencing the process of parasitic infection and thus foster our understanding of the disease pathogenesis.

Differential in vitro activity of the DNA topoisomerase inhibitor idarubicin against Trypanosoma rangeli and Trypanosoma cruzi

In this study the effect of eight DNA topoisomerase inhibitors on the growth Trypanosoma rangeli epimastigotes in cell culture was investigated. Among the eight compounds tested, idarubicin was the only compound that displayed promising trypanocidal activity with a half-maximal growth inhibition (GI50) value in the sub-micromolar range. Fluorescence-activated cell sorting analysis showed a reduction in DNA content in T. rangeli epimastigotes when treated with idarubicin. In contrast to T. rangeli, against Trypanosoma cruzi epimastigotes idarubicin was much less effective exhibiting a GI50 value in the mid-micromolar range. This result indicates that idarubicin displays differential toxic effects in T. rangeli and T. cruzi. Compared with African trypanosomes, it seems that American trypanosomes are generally less susceptible to DNA topoisomerase inhibitors.

Physiopathologie du coeur embryonnaire soumis à l'anoxie-réoxygénation: rôle protecteur du NO et des canaux KATP

RESUME Introduction : Dans le coeur adulte, l'ischémie et la reperfusion entraînent des perturbations électriques, mécaniques, biochimiques et structurales qui peuvent causer des dommages réversibles ou irréversibles selon la sévérité de l'ischémie. Malgré les récents progrès en cardiologie et en chirurgie foetales, la connaissance des mécanismes impliqués dans la réponse du myocarde embryonnaire à un stress hypoxique transitoire demeure lacunaire. Le but de ce travail a donc été de caractériser les effets chrono-, dromo- et inotropes de l'anoxie et de la réoxygénation sur un modèle de coeur embryonnaire isolé. D'autre part, les effets du monoxyde d'azote (NO) et de la modulation des canaux KATP mitochondriaux (mito KATP) sur la récupération fonctionnelle postanoxique ont été étudiés. La production myocardique de radicaux d'oxygène (ROS) et l'activité de MAP Kinases (ERK et JNK) impliquées dans la signalisation cellulaire ont également été déterminées. Méthodes : Des coeurs d'embryons de poulet âgés de 4 jours battant spontanément ont été placés dans une chambre de culture puis soumis à une anoxie de 30 min suivie d'une réoxygénation de 60 min. L'activité électrique (ECG), les contractions de l'oreillette, du ventricule et du conotroncus (détectées par photométrie), la production de ROS (mesure de la fluorescence du DCFH) et l'activité kinase de ERK et JNK dans le ventricule ont été déterminées au cours de l'anoxie et de la réoxygénation. Les coeurs ont été traités avec un bloqueur des NO synthases (L-NAME), un donneur de NO (DETA-NONOate), un activateur (diazoxide) ou un inhibiteur (5-HD) des canaux mitoKATP un inhibiteur non-spécifique des PKC (chélérythrine) ou un piégeur de ROS (MPG). Résultats : L'anoxie et la réoxygénation entraînaient des arythmies (essentiellement d'origine auriculaire) semblables à celles observées chez l'adulte, des troubles de la conduction (blocs auriculo-ventriculaires de 1er, 2ème et 3ème degré) et un ralentissement marqué du couplage excitation-contraction (E-C) ventriculaire. En plus de ces arythmies, la réoxygénation déclenchait le phénomène de Wenckelbach, de rares échappements ventriculaires et une sidération myocardique. Aucune fibrillation, conduction rétrograde ou activité ectopique n'ont été observées. Le NO exogène améliorait la récupération postanoxique du couplage E-C ventriculaire alors que L'inhibition des NOS la ralentissait. L'activation des canaux mito KATP augmentait la production mitochondriale de ROS à la réoxygénation et accélérait la récupération de la conduction (intervalle PR) et du couplage E-C ventriculaire. La protection de ce couplage était abolie par le MPG, la chélérythrine ou le L-NAME. Les fonctions électrique et contractile de tous les coeurs récupéraient après 30-40 min de réoxygénation. L'activité de ERK et de JNK n'était pas modifiée par L'anoxie, mais doublait et quadruplait, respectivement, après 30 min de réoxygénation. Seule l'activité de JNK était diminuée (-60%) par l'activation des canaux mitoKATP. Cet effet inhibiteur était partiellement abolit par le 5-HD. Conclusion: Dans le coeur immature, le couplage E-C ventriculaire semble être un paramètre particulièrement sensible aux conditions d'oxygénation. Sa récupération postanoxique est améliorée par l'ouverture des canaux mitoKATP via une signalisation impliquant les ROS Ies PKC et le NO. Une réduction de l'activité de JNK semble également participer à cette protection. Nos résultats suggèrent que les mitochondries jouent un rôle central dans la modulation des voies de signalisation cellulaire, en particulier lorsque les conditions métaboliques deviennent défavorables. Le coeur embryonnaire isolé représente donc un modèle expérimental utile pour mieux comprendre les mécanismes associés à une hypoxie in utero et pour améliorer les stratégies thérapeutiques en cardiologie et chirurgie foetales. ABSTRACT Physiopathology of the anoxic-reoxygenated embryonic heart: Protective role of NO and KATP channel Aim: In the adult heart, the electrical, mechanical, biochemical and structural disturbances induced by ischemia and reperfusion lead to reversible or irreversible damages depending on the severity and duration of ischemia. In spite of recent advances in fetal cardiology and surgery, little is known regarding the cellular mechanisms involved in hypoxia-induced dysfunction in the developing heart. The aim of this study was to precisely characterize the chrono-, dromo- and inotropic disturbances associated with anoxia-reoxygenation in an embryonic heart model. Furthermore, the roles that nitric oxide (NO), reactive oxygen species (ROS), mitochondrial KATP, (mito KATP) channel and MAP Kinases could play in the stressed developing heart have been investigated. Methods: Embryonic chick hearts (4-day-old) were isolated and submitted in vitro to 30 min anoxia followed by 60 min reoxygenation. Electrical (ECG) and contractile activities of atria, ventricle and conotruncus (photometric detection), ROS production (DCFH fluorescence) and ERK and JNK activity were determined in the ventricle throughout anoxia-reoxygenation. Hearts were treated with NO synthase inhibitor (L-NAME), NO donor (DETA-NONOate), mitoKATP channel opener (diazoxide) or blocket (5-HD), PKC inhibitor (chelerythrine) and ROS scavenger (MPG). Results: Anoxia and reoxygenation provoked arrhythxnias (mainly originating from atrial region), troubles of conduction (st, 2nd, and 3rd degree atrio-ventricular blocks) and disturbances of excitation-contraction (E-C) coupling. In addition to these types of arrhythmias, reoxygenation triggered Wenckebach phenomenon and rare ventricular escape beats. No fibrillations, no ventricular ectopic beats and no electromechanical dissociation were observed. Myocardial stunning was observed during the first 30 min of reoxygenation. All hearts fully recovered their electrical and mechanical functions after 30-40 min of reoxygenation. Exogenous NO improved while NOS inhibition delayed E-C coupling recovery. Mito KATP, channel opening increased reoxygenation-induced ROS production and improved E-C coupling and conduction (PR) recovery. MPG, chelerythrine or L-NAME reversed this effect. Reoxygenation increased ERK and JNK activities land 4-fold, respectively, while anoxia had no effect. MitoKATP channel opening abolished the reoxygenation-induced activation of JNK but had no effect on ERK activity. This inhibitory effect was partly reversed by mitoKATP channel blocker but not by MPG. Conclusion: In the developing heart, ventricular E-C coupling was found to be specially sensitive to hypoxia-reoxygenation and its postanoxic recovery was improved by mitoKATP channel activation via a ROS-, PKC- and NO-dependent pathway. JNK inhibition appears to be involved in this protection. Thus, mitochondria can play a pivotal role in the cellular signalling pathways, notably under critical metabolic conditions. The model of isolated embryonic heart appears to be useful to better understand the mechanisms underlying the myocardial dysfunction induced by an in utero hypoxia and to improve therapeutic strategies in fetal cardiology and surgery.

In vitro and in vivo antimalarial activity and cytotoxicity of extracts, fractions and a substance isolated from the Amazonian plant Tachia grandiflora (Gentianaceae)

Tachia sp. are used as antimalarials in the Amazon Region and in vivo antimalarial activity of a Tachia sp. has been previously reported. Tachia grandiflora Maguire and Weaver is an Amazonian antimalarial plant and herein its cytotoxicity and antimalarial activity were investigated. Spectral analysis of the tetraoxygenated xanthone decussatin and the iridoid aglyone amplexine isolated, respectively, from the chloroform fractions of root methanol and leaf ethanol extracts was performed. In vitro inhibition of the growth of Plasmodium falciparum Welch was evaluated using optical microscopy on blood smears. Crude extracts of leaves and roots were inactive in vitro. However, chloroform fractions of the root and leaf extracts [half-maximal inhibitory concentration (IC50) = 10.5 and 35.8 µg/mL, respectively] and amplexine (IC50= 7.1 µg/mL) were active in vitro. Extracts and fractions were not toxic to type MRC-5 human fibroblasts (IC50> 50 µg/mL). Water extracts of the roots of T. grandiflora administered by mouth were the most active extracts in the Peters 4-day suppression test in Plasmodium berghei-infected mice. At 500 mg/kg/day, these extracts exhibited 45-59% inhibition five to seven days after infection. T. grandiflora infusions, fractions and isolated substance have potential as antimalarials.

The antioxidant effect of β-caryophyllene protects rat liver from carbon tetrachloride-induced fibrosis by inhibiting hepatic stellate cell activation.

Plant-based whole foods provide thousands of bioactive metabolites to the human diet that reduce the risk of developing chronic diseases. β-Caryophyllene (CAR) is a common constituent of the essential oil of numerous plants, vegetables, fruits and medicinal herbs, and has been used as a flavouring agent since the 1930 s. Here, we report the antioxidant activity of CAR, its protective effect on liver fibrosis and its inhibitory capacity on hepatic stellate cell (HSC) activation. CAR was tested for the inhibition of lipid peroxidation and as a free radical scavenger. CAR had higher inhibitory capacity on lipid peroxidation than probucol, α-humulene and α-tocopherol. Also, CAR showed high scavenging activities against hydroxyl radical and superoxide anion. The activity of 5-lipoxygenase, an enzyme that actively participates in fibrogenesis, was significantly inhibited by CAR. Carbon tetrachloride-treated rats received CAR at 2, 20 and 200 mg/kg. CAR significantly improved liver structure, and reduced fibrosis and the expression of Col1a1, Tgfb1 and Timp1 genes. Oxidative stress was used to establish a model of HSC activation with overproduction of extracellular matrix proteins. CAR (1 and 10 μm) increased cell viability and significantly reduced the expression of fibrotic marker genes. CAR, a sesquiterpene present in numerous plants and foods, is as a natural antioxidant that reduces carbon tetrachloride-mediated liver fibrosis and inhibits hepatic cell activation.

Cholinergic regulation of bone.

Bone remodeling is regulated by the two branches of the autonomic nervous system: the adrenergic and the cholinergic branches. Adrenergic activity favors bone loss, whereas cholinergic activity has been recently shown to favor bone mass accrual. In vitro studies have reported that cholinergic activity induces proliferation and differentiation of bone cells. In vivo studies have shown that the inhibition of cholinergic activity favors bone loss, whereas its stimulation favors bone mass accrual. Clinical studies have shown that bone density is associated with the function of many cholinergic-regulated tissues such as the hypothalamus, salivary glands, lacrimal glands and langerhans cells, suggesting a common mechanism of control. Altogether, these observations and linked findings are of great significance since they improve our understanding of bone physiology. These discoveries have been successfully used recently to investigate new promising therapies for bone diseases based on cholinergic stimulation. Here, we review the current understanding of the cholinergic activity and its association with bone health.

The forgotten face of regular physical exercise: a 'natural' anti-atherogenic activity.

Humans are not programmed to be inactive. The combination of both accelerated sedentary lifestyle and constant food availability disturbs ancient metabolic processes leading to excessive storage of energy in tissue, dyslipidaemia and insulin resistance. As a consequence, the prevalence of Type 2 diabetes, obesity and the metabolic syndrome has increased significantly over the last 30 years. A low level of physical activity and decreased daily energy expenditure contribute to the increased risk of cardiovascular morbidity and mortality following atherosclerotic vascular damage. Physical inactivity leads to the accumulation of visceral fat and consequently the activation of the oxidative stress/inflammation cascade, which promotes the development of atherosclerosis. Considering physical activity as a 'natural' programmed state, it is assumed that it possesses atheroprotective properties. Exercise prevents plaque development and induces the regression of coronary stenosis. Furthermore, experimental studies have revealed that exercise prevents the conversion of plaques into a vulnerable phenotype, thus preventing the appearance of fatal lesions. Exercise promotes atheroprotection possibly by reducing or preventing oxidative stress and inflammation through at least two distinct pathways. Exercise, through laminar shear stress activation, down-regulates endothelial AT1R (angiotensin II type 1 receptor) expression, leading to decreases in NADPH oxidase activity and superoxide anion production, which in turn decreases ROS (reactive oxygen species) generation, and preserves endothelial NO bioavailability and its protective anti-atherogenic effects. Contracting skeletal muscle now emerges as a new organ that releases anti-inflammatory cytokines, such as IL-6 (interleukin-6). IL-6 inhibits TNF-α (tumour necrosis factor-α) production in adipose tissue and macrophages. The down-regulation of TNF-α induced by skeletal-muscle-derived IL-6 may also participate in mediating the atheroprotective effect of physical activity.

Chronic nitric oxide synthase inhibition and carotid artery distensibility in renal hypertensive rats.

The goal of the present study was to examine the viscoelastic properties of the carotid artery in genetically identical rats exposed to similar levels of blood pressure sustained by different mechanisms. Eight-week old male Wistar rats were examined 2 weeks after renal artery clipping (two-kidney, one clip [2K1C] Goldblatt rats, n = 53) or sham operation (n = 49). One half of the 2K1C and sham rats received the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 1.48 mmol/L) in their drinking water for 2 weeks after the surgical procedure. Mean blood pressure increased significantly in the 2K1C-water (182 mm Hg), 2K1C-L-NAME (197 mm Hg), and sham-L-NAME (170 mm Hg) rats compared with the sham-water rats (127 mm Hg). Plasma renin activity was not altered by L-NAME but significantly enhanced after renal artery clipping. A significant and similar increase in the cross-sectional area of the carotid artery was observed in L-NAME and vehicle-treated 2K1C rats. L-NAME per se did not modify cross-sectional area in the sham rats. There was a significant upward shift of the distensibility-pressure curve in the L-NAME- and vehicle-treated 2K1C rats compared with the sham-L-NAME rats. L-NAME treatment did not alter the distensibility-pressure curve in the 2K1C rats. These results demonstrate that the mechanisms responsible for artery wall hypertrophy in renovascular hypertension are accompanied by an increase in arterial distensibility that is not dependent on the synthesis of nitric oxide.

In vivo enzymatic activity of acetylCoA synthetase in skeletal muscle revealed by 13C turnover from hyperpolarized [1-13C]acetate to [1-13C]acetylcarnitine

BACKGROUND: Acetate metabolism in skeletal muscle is regulated by acetylCoA synthetase (ACS). The main function of ACS is to provide cells with acetylCoA, a key molecule for numerous metabolic pathways including fatty acid and cholesterol synthesis and the Krebs cycle. METHODS: Hyperpolarized [1-(13)C]acetate prepared via dissolution dynamic nuclear polarization was injected intravenously at different concentrations into rats. The (13)C magnetic resonance signals of [1-(13)C]acetate and [1-(13)C]acetylcarnitine were recorded in vivo for 1min. The kinetic rate constants related to the transformation of acetate into acetylcarnitine were deduced from the 3s time resolution measurements using two approaches, either mathematical modeling or relative metabolite ratios. RESULTS: Although separated by two biochemical transformations, a kinetic analysis of the (13)C label flow from [1-(13)C]acetate to [1-(13)C]acetylcarnitine led to a unique determination of the activity of ACS. The in vivo Michaelis constants for ACS were KM=0.35±0.13mM and Vmax=0.199±0.031μmol/g/min. CONCLUSIONS: The conversion rates from hyperpolarized acetate into acetylcarnitine were quantified in vivo and, although separated by two enzymatic reactions, these rates uniquely defined the activity of ACS. The conversion rates associated with ACS were obtained using two analytical approaches, both methods yielding similar results. GENERAL SIGNIFICANCE: This study demonstrates the feasibility of directly measuring ACS activity in vivo and, since the activity of ACS can be affected by various pathological states such as cancer or diabetes, the proposed method could be used to non-invasively probe metabolic signatures of ACS in diseased tissue.

Specific processing of tenascin-C by the metalloprotease meprin beta neutralizes its inhibition of cell spreading

The metalloprotease meprin has been implicated in tissue remodelling due to its capability to degrade extracellular matrix components. Here, we investigated the susceptibility of tenascin-C to cleavage by meprin beta and the functional properties of its proteolytic fragments. A set of monoclonal antibodies against chicken and human tenascin-C allowed the mapping of proteolytic fragments generated by meprin beta. In chicken tenascin-C, meprin beta processed all three major splicing variants by removal of 10 kDa N-terminal and 38 kDa C-terminal peptides, leaving a large central part of subunits intact. IN similar cleavage pattern was found for large human tenascin-C variant where two N-terminal peptides (10 or 15 kDa) and two C-terminal fragments (40 and 55 kDa) were removed from the intact subunit. N-terminal sequencing revealed the exact amino acid positions of cleavage sites. In both chicken and human tenascin-C N-terminal cleavages occurred just before and/or after the heptad repeats involved in subunit oligomerization. In the human protein, an additional cleavage site was identified in the alternative fibronectin type III repeat D. Whereas all these sites are known to be attacked by several other proteases, a unique cleavage by meprin beta was located to the 7th constant fibronectin type III repeat in both chicken and human tenascin-C, thereby removing the C-terminal domain involved in its anti-adhesive activity. In cell adhesion assays meprin beta-digested human tenascin-C was not able to interfere with fibronectin-mediated cell spreading, confirming cleavage in the anti-adhesive domain. Whereas the expression of meprin beta and tenascin-C does not overlap in normal colon tissue, inflamed lesions of the mucosa from patients with Crohn's disease exhibited many meprin beta-positive leukocytes in regions where tenascin-C was strongly induced. Our data indicate that, at least under pathological conditions, meprin beta might attack specific functional sites in tenascin-C that are important for its oligomerization and anti-adhesive activity. (C) 2009 Elsevier B.V. All rights reserved.

PARP inhibition attenuates histopathological lesion in ischemia/reperfusion renal mouse model after cold prolonged ischemia.

We test the hypothesis that PARP inhibition can decrease acute tubular necrosis (ATN) and other renal lesions related to prolonged cold ischemia/reperfusion (IR) in kidneys preserved at 4°C in University of Wisconsin (UW) solution. Material and Methods. We used 30 male Parp1(+/+) wild-type and 15 male Parp1(0/0) knockout C57BL/6 mice. Fifteen of these wild-type mice were pretreated with 3,4-dihydro-5-[4-(1-piperidinyl)butoxyl]-1(2H)-isoquinolinone (DPQ) at a concentration of 15 mg/kg body weight, used as PARP inhibitor. Subgroups of mice were established (A: IR 45 min/6 h; B: IR + 48 h in UW solution; and C: IR + 48 h in UW solution plus DPQ). We processed samples for morphological, immunohistochemical, ultrastructural, and western-blotting studies. Results. Prolonged cold ischemia time in UW solution increased PARP-1 expression and kidney injury. Preconditioning with PARP inhibitor DPQ plus DPQ supplementation in UW solution decreased PARP-1 nuclear expression in renal tubules and renal damage. Parp1(0/0) knockout mice were more resistant to IR-induced renal lesion. In conclusion, PARP inhibition attenuates ATN and other IR-related renal lesions in mouse kidneys under prolonged cold storage in UW solution. If confirmed, these data suggest that pharmacological manipulation of PARP activity may have salutary effects in cold-stored organs at transplantation.

Poly(ADP-ribose) polymerases as modulators of mitochondrial activity.

Mitochondria are essential in cellular stress responses. Mitochondrial output to environmental stress is a major factor in metabolic adaptation and is regulated by a complex network of energy and nutrient sensing proteins. Activation of poly(ADP-ribose) polymerases (PARPs) has been known to impair mitochondrial function; however, our view of PARP-mediated mitochondrial dysfunction and injury has only recently fundamentally evolved. In this review, we examine our current understanding of PARP-elicited mitochondrial damage, PARP-mediated signal transduction pathways, transcription factors that interact with PARPs and govern mitochondrial biogenesis, as well as mitochondrial diseases that are mediated by PARPs. With PARP activation emerging as a common underlying mechanism in numerous pathologies, a better understanding the role of various PARPs in mitochondrial regulation may help open new therapeutic avenues.

PARP inhibition attenuates histopathological lesion in ischemia/reperfusion renal mouse model after cold prolonged ischemia.

We test the hypothesis that PARP inhibition can decrease acute tubular necrosis (ATN) and other renal lesions related to prolonged cold ischemia/reperfusion (IR) in kidneys preserved at 4°C in University of Wisconsin (UW) solution. Material and Methods. We used 30 male Parp1(+/+) wild-type and 15 male Parp1(0/0) knockout C57BL/6 mice. Fifteen of these wild-type mice were pretreated with 3,4-dihydro-5-[4-(1-piperidinyl)butoxyl]-1(2H)-isoquinolinone (DPQ) at a concentration of 15 mg/kg body weight, used as PARP inhibitor. Subgroups of mice were established (A: IR 45 min/6 h; B: IR + 48 h in UW solution; and C: IR + 48 h in UW solution plus DPQ). We processed samples for morphological, immunohistochemical, ultrastructural, and western-blotting studies. Results. Prolonged cold ischemia time in UW solution increased PARP-1 expression and kidney injury. Preconditioning with PARP inhibitor DPQ plus DPQ supplementation in UW solution decreased PARP-1 nuclear expression in renal tubules and renal damage. Parp1(0/0) knockout mice were more resistant to IR-induced renal lesion. In conclusion, PARP inhibition attenuates ATN and other IR-related renal lesions in mouse kidneys under prolonged cold storage in UW solution. If confirmed, these data suggest that pharmacological manipulation of PARP activity may have salutary effects in cold-stored organs at transplantation.