Knockdown of ANGPTL2 promotes left ventricular systolic dysfunction by upregulation of NOX4 in mice.

Background: Angiopoietin-like 2 (ANGPTL2) is a pro-inflammatory and pro-oxidant circulating protein that predicts and promotes chronic inflammatory diseases such as atherosclerosis in humans. Transgenic murine models demonstrated the deleterious role of ANGPTL2 in vascular diseases, while deletion of ANGPTL2 was protective. The nature of its role in cardiac tissues is, however, less clear. Indeed, in adult mice knocked down (KD) for ANGPTL2, we recently reported a mild left ventricular (LV) dysfunction originating from a congenital aortic valve stenosis, demonstrating that ANGPTL2 is essential to cardiac development and function. Hypothesis: Because we originally demonstrated that the KD of ANGPTL2 protected vascular endothelial function via an upregulation of arterial NOX4, promoting the beneficial production of dilatory H2O2, we tested the hypothesis that increased cardiac NOX4 could negatively affect cardiac redox and remodeling and contribute to LV dysfunction observed in adult Angptl2-KD mice. Methods and results: Cardiac expression and activity of NOX4 were higher in KD mice, promoting higher levels of cardiac H2O2 when compared to wild-type (WT) mice. Immunofluorescence showed that ANGPTL2 and NOX4 were co-expressed in cardiac cells from WT mice and both proteins co-immunoprecipitated in HEK293 cells, suggesting that ANGPTL2 and NOX4 physically interact. Pressure overload induced by transverse aortic constriction surgery (TAC) promoted LV systolic dysfunction in WT mice but did not further exacerbate the dysfunction in KD mice. Importantly, the severity of LV systolic dysfunction in KD mice (TAC and control SHAM) correlated with cardiac Nox4 expression. Injection of an adeno-associated virus (AAV9) delivering shRNA targeting cardiac Nox4 expression fully reversed LV systolic dysfunction in KD-SHAM mice, demonstrating the causal role of NOX4 in cardiac dysfunction in KD mice. Targeting cardiac Nox4 expression in KD mice also induced an antioxidant response characterized by increased expression of NRF2/KEAP1 and catalase. Conclusion: Together, these data reveal that the absence of ANGPTL2 induces an upregulation of cardiac NOX4 that contributes to oxidative stress and LV dysfunction. By interacting and repressing cardiac NOX4, ANGPTL2 could play a new beneficial role in the maintenance of cardiac redox homeostasis and function.

Adipose tissue senescence is mediated by increased ATP content after a short-term high-fat diet exposure.

In the context of obesity, senescent cells accumulate in white adipose tissue (WAT). The cellular underpinnings of WAT senescence leading to insulin resistance are not fully elucidated. The objective of the current study was to evaluate the presence of WAT senescence early after initiation of high-fat diet (HFD, 1-10 weeks) in 5-month-old male C57BL/6J mice and the potential role of energy metabolism. We first showed that WAT senescence occurred 2 weeks after HFD as evidenced in whole WAT by increased senescence-associated ß-galactosidase activity and cyclin-dependent kinase inhibitor 1A and 2A expression. WAT senescence affected various WAT cell populations, including preadipocytes, adipose tissue progenitors, and immune cells, together with adipocytes. WAT senescence was associated with higher glycolytic and mitochondrial activity leading to enhanced ATP content in HFD-derived preadipocytes, as compared with chow diet-derived preadipocytes. One-month daily exercise, introduced 5 weeks after HFD, was an effective senostatic strategy, since it reversed WAT cellular senescence, while reducing glycolysis and production of ATP. Interestingly, the beneficial effect of exercise was independent of body weight and fat mass loss. We demonstrated that WAT cellular senescence is one of the earliest events occurring after HFD initiation and is intimately linked to the metabolic state of the cells. Our data uncover a critical role for HFD-induced elevated ATP as a local danger signal inducing WAT senescence. Exercise exerts beneficial effects on adipose tissue bioenergetics in obesity, reversing cellular senescence, and metabolic abnormalities.

Dysregulated Phenylalanine Catabolism Plays a Key Role in the Trajectory of Cardiac Aging.

BACKGROUND: Aging myocardium undergoes progressive cardiac hypertrophy and interstitial fibrosis with diastolic and systolic dysfunction. Recent metabolomics studies shed light on amino acids in aging. The present study aimed to dissect how aging leads to elevated plasma levels of the essential amino acid phenylalanine and how it may promote age-related cardiac dysfunction. METHODS: We studied cardiac structure and function, together with phenylalanine catabolism in wild-type (WT) and p21-/- mice (male; 2-24 months), with the latter known to be protected from cellular senescence. To explore phenylalanine's effects on cellular senescence and ectopic phenylalanine catabolism, we treated cardiomyocytes (primary adult rat or human AC-16) with phenylalanine. To establish a role for phenylalanine in driving cardiac aging, WT male mice were treated twice a day with phenylalanine (200 mg/kg) for a month. We also treated aged WT mice with tetrahydrobiopterin (10 mg/kg), the essential cofactor for the phenylalanine-degrading enzyme PAH (phenylalanine hydroxylase), or restricted dietary phenylalanine intake. The impact of senescence on hepatic phenylalanine catabolism was explored in vitro in AML12 hepatocytes treated with Nutlin3a (a p53 activator), with or without p21-targeting small interfering RNA or tetrahydrobiopterin, with quantification of PAH and tyrosine levels. RESULTS: Natural aging is associated with a progressive increase in plasma phenylalanine levels concomitant with cardiac dysfunction, whereas p21 deletion delayed these changes. Phenylalanine treatment induced premature cardiac deterioration in young WT mice, strikingly akin to that occurring with aging, while triggering cellular senescence, redox, and epigenetic changes. Pharmacological restoration of phenylalanine catabolism with tetrahydrobiopterin administration or dietary phenylalanine restriction abrogated the rise in plasma phenylalanine and reversed cardiac senescent alterations in aged WT mice. Observations from aged mice and human samples implicated age-related decline in hepatic phenylalanine catabolism as a key driver of elevated plasma phenylalanine levels and showed increased myocardial PAH-mediated phenylalanine catabolism, a novel signature of cardiac aging. CONCLUSIONS: Our findings establish a pathogenic role for increased phenylalanine levels in cardiac aging, linking plasma phenylalanine levels to cardiac senescence via dysregulated phenylalanine catabolism along a hepatic-cardiac axis. They highlight phenylalanine/PAH modulation as a potential therapeutic strategy for age-associated cardiac impairment.

The Phosin PptA Plays a Negative Role in the Regulation of Antibiotic Production in Streptomyces lividans.

In Streptomyces, antibiotic biosynthesis is triggered in phosphate limitation that is usually correlated with energetic stress. Polyphosphates constitute an important reservoir of phosphate and energy and a better understanding of their role in the regulation of antibiotic biosynthesis is of crucial importance. We previously characterized a gene, SLI_4384/ppk, encoding a polyphosphate kinase, whose disruption greatly enhanced the weak antibiotic production of Streptomyces lividans. In the condition of energetic stress, Ppk utilizes polyP as phosphate and energy donor, to generate ATP from ADP. In this paper, we established that ppk is co-transcribed with its two downstream genes, SLI_4383, encoding a phosin called PptA possessing a CHAD domain constituting a polyphosphate binding module and SLI_4382 encoding a nudix hydrolase. The expression of the ppk/pptA/SLI_4382 operon was shown to be under the positive control of the two-component system PhoR/PhoP and thus mainly expressed in condition of phosphate limitation. However, pptA and SLI_4382 can also be transcribed alone from their own promoter. The deletion of pptA resulted into earlier and stronger actinorhodin production and lower lipid content than the disruption of ppk, whereas the deletion of SLI_4382 had no obvious phenotypical consequences. The disruption of ppk was shown to have a polar effect on the expression of pptA, suggesting that the phenotype of the ppk mutant might be linked, at least in part, to the weak expression of pptA in this strain. Interestingly, the expression of phoR/phoP and that of the genes of the pho regulon involved in phosphate supply or saving were strongly up-regulated in pptA and ppk mutants, revealing that both mutants suffer from phosphate stress. Considering the presence of a polyphosphate binding module in PptA, but absence of similarities between PptA and known exo-polyphosphatases, we proposed that PptA constitutes an accessory factor for exopolyphosphatases or general phosphatases involved in the degradation of polyphosphates into phosphate.

Lack of angiopoietin-like-2 expression limits the metabolic stress induced by a high-fat diet and maintains endothelial function in mice.

BACKGROUND: Angiopoietin-like-2 (angptl2) is produced by several cell types including endothelial cells, adipocytes and macrophages, and contributes to the inflammatory process in cardiovascular diseases. We hypothesized that angptl2 impairs endothelial function, and that lowering angptl2 levels protects the endothelium against high-fat diet (HFD)-induced fat accumulation and hypercholesterolemia. METHODS AND RESULTS: Acute recombinant angptl2 reduced (P<0.05) acetylcholine-mediated vasodilation of isolated wild-type (WT) mouse femoral artery, an effect reversed (P<0.05) by the antioxidant N-acetylcysteine. Accordingly, in angptl2 knockdown (KD) mice, ACh-mediated endothelium-dependent vasodilation was greater (P<0.05) than in WT mice. In arteries from KD mice, prostacyclin contributed to the overall dilation unlike in WT mice. After a 3-month HFD, overall vasodilation was not altered, but dissecting out the endothelial intrinsic pathways revealed that NO production was reduced in arteries isolated from HFD-fed WT mice (P<0.05), while NO release was maintained in KD mice. Similarly, endothelium-derived hyperpolarizing factor (EDHF) was preserved in mesenteric arteries from HFD-fed KD mice but not in those from WT mice. Finally, the HFD increased (P<0.05) total cholesterol-to-high-density lipoprotein ratios, low-density lipoprotein-to-high-density lipoprotein ratios, and leptin levels in WT mice only, while glycemia remained similar in the 2 strains. KD mice displayed less triglyceride accumulation in the liver (P<0.05 versus WT), and adipocyte diameters in mesenteric and epididymal white adipose tissues were smaller (P<0.05) in KD than in WT fed an HFD, while inflammatory gene expression increased (P<0.05) in the fat of WT mice only. CONCLUSIONS: Lack of angptl2 expression limits the metabolic stress induced by an HFD and maintains endothelial function in mice.

Functional and genetic characterization of two extremely rare cases of Williams-Beuren syndrome associated with chronic granulomatous disease.

Williams-Beuren syndrome (WBS) is a neurodevelopmental disorder with multi-systemic manifestations, caused by a heterozygous segmental deletion of 1.55-1.83 Mb at chromosomal band 7q11.23. The deletion can include the NCF1 gene that encodes the p47(phox) protein, a component of the leukocyte NADPH oxidase enzyme, which is essential for the defense against microbial pathogens. It has been postulated that WBS patients with two functional NCF1 genes are more susceptible to occurrence of hypertension than WBS patients with only one functional NCF1 gene. We now describe two extremely rare WBS patients without any functional NCF1 gene, because of a mutation in NCF1 on the allele not carrying the NCF1-removing WBS deletion. These two patients suffer from chronic granulomatous disease with increased microbial infections in addition to WBS. Interestingly, one of these patients did suffer from hypertension, indicating that other factors than NADPH oxidase in vascular tissue may be involved in causing hypertension.

Inhibition of the Mitochondrial Permeability Transition for Cytoprotection: Direct versus Indirect Mechanisms.

Mitochondria are fascinating organelles, which fulfill multiple cellular functions, as diverse as energy production, fatty acid ß oxidation, reactive oxygen species (ROS) production and detoxification, and cell death regulation. The coordination of these functions relies on autonomous mitochondrial processes as well as on sustained cross-talk with other organelles and/or the cytosol. Therefore, this implies a tight regulation of mitochondrial functions to ensure cell homeostasis. In many diseases (e.g., cancer, cardiopathies, nonalcoholic fatty liver diseases, and neurodegenerative diseases), mitochondria can receive harmful signals, dysfunction and then, participate to pathogenesis. They can undergo either a decrease of their bioenergetic function or a process called mitochondrial permeability transition (MPT) that can coordinate cell death execution. Many studies present evidence that protection of mitochondria limits disease progression and severity. Here, we will review recent strategies to preserve mitochondrial functions via direct or indirect mechanisms of MPT inhibition. Thus, several mitochondrial proteins may be considered for cytoprotective-targeted therapies.

Clinical, functional and genetic analysis of twenty-four patients with chronic granulomatous disease - identification of eight novel mutations in CYBB and NCF2 genes.

Chronic granulomatous disease is an inherited disorder in which phagocytes lack a functional NADPH oxidase and cannot produce superoxide anions. The most common form is caused by mutations in CYBB encoding gp91phox. We investigated 24 CGD patients and their families. Twenty-one mutations in CYBB were classified as X91(0), X91(+) or X91(-) variants according to cytochrome b (558) expression. Point mutations in encoding regions represented 50 % of the mutations found in CYBB, splice site mutations 27 %, deletions and insertions 23 %. Eight mutations in CYBB were novel leading to X91(0)CGD cases. Two of these were point mutations: c493G>T and a double mutation c625C>G in exon 6 and c1510C>T in exon 12 leading to a premature stop codon at Gly165 in gp91phox and missense mutations His209Arg/Thr503Ile respectively. Two novel splice mutations in 5'intronic regions of introns 1 and 6 were found. A novel deletion/insertion c1024_1026delCTG/insT results in a frameshift introducing a stop codon at position 346 in gp91phox. The last novel mutation was the insertion of a T at c1373 leading to a frameshift and a premature stop codon at position 484 in gp91phox. For the first time the precise size of two large mutations in CYBB was determined by array-comparative genomic hybridization and carriers' status were evaluated by multiplex ligation-dependent probe amplification assay. No clear correlation between clinical severity and CYBB mutations could be established. Of three mutations in CYBA, NCF1 and NCF2 leading to rare autosomal recessive CGD, one nonsense mutation c29G>A in exon 1 of NCF2 was new.

Rare duplication or deletion of exons 6, 7 and 8 in CYBB leading to X-linked chronic granulomatous disease in two patients from different families.

Chronic granulomatous disease (CGD) is a rare congenital disorder in which phagocytes cannot generate superoxide (O(2)(-)) and other microbicidal oxidants due to mutations in one of the five components of the O(2)(-)-generating NADPH oxidase complex. The most common form is caused by mutations in CYBB on the X chromosome, encoding gp91phox, the enzymatic subunit of the phagocyte NADPH oxidase. Here, we report two rare cases of male X-linked CGD patients, one caused by a 5.7-kb duplication of a region containing CYBB exons 6 to 8 and the other caused by a deletion of this same region. We found both the duplication in patient 1 and the deletion in patient 2 to be bordered by a GT repeat. Indeed, in control DNA, the 3' part of CYBB intron 5 contains a GT repeat and the 5' part of intron 8 also contains such a repeat. Duplication of exons 6, 7 and 8 in patient 1 was probably caused by a non-homologous crossing over between the two GT repeats. The deletion found in patient 2 probably arose from a similar misalignment. The results found in these patients were confirmed by multiplex ligation-dependent probe amplification. The clinical profile of XCGD is severe in both patients.

Non-alcoholic steatohepatitis: new insights from OMICS studies.

Non-alcoholic fatty liver disease (NAFLD) is the most common liver pathology characterized by fat accumulation in a context of metabolic syndrome or insulin resistance. It can be associated with obesity, diabetes, hyperinsulinemia, dyslipidemia as well as hypertension. NAFLD consists of a large spectrum of hepatic lesions including benign steatosis, non-alcoholic steatohepatitis (NASH), cirrhosis or hepatocellular carcinoma. Upon chronic stress, NASH would occur via at least "two-hits" process involving modulation of a high number of genes and proteins. Firstly, the accumulation of fat, either due to the increased inflow of free fatty acids or de novo lipogenesis, leads to steatosis. Secondly, when adaptive mechanisms for stress tolerance are overwhelmed, lipotoxicity and chronic inflammation trigger major hepatic damages, mainly via oxidative and inflammatory stress, lipid peroxidation and cell death. As a consequence, all these processes concur to favor steatohepatitis, fibrosis and cancer. Recently, the elucidation of physiopathological signaling cascades controlling NAFLD and NASH benefited from large-scale studies, namely the omics, such as transcriptomics, genomics, proteomics, and lipidomics. The advent of lipidomics would allow shedding light upon the respective roles of triglyceride and fatty acid metabolites in the lipotoxic liver injury hypothesis for the pathogenesis of NASH. In this review, the contribution of the omics to the understanding of the molecular basis of NASH is discussed that could offer perspectives for novel biomarkers discovery.

Withaferin A induces apoptosis in human melanoma cells through generation of reactive oxygen species and down-regulation of Bcl-2.

A high resistance and heterogeneous response to conventional anti-cancer chemotherapies characterize malignant cutaneous melanoma, the most aggressive and deadly form of skin cancer. Withaferin A (WFA), a withanolide derived from the medicinal plant Withania somnifera, has been reported for its anti-tumorigenic activity against various cancer cells. For the first time, we examined the death-inducing potential of WFA against a panel of four different human melanoma cells and investigated the cellular mechanisms involved. WFA induces apoptotic cell death with various IC50 ranging from 1.8 to 6.1 µM. The susceptibility of cells toward WFA-induced apoptosis correlated with low Bcl-2/Bax and Bcl-2/Bim ratios. In all cell lines, the apoptotic process triggered by WFA involves the mitochondrial pathway and was associated with Bcl-2 down regulation, Bax mitochondrial translocation, cytochrome c release into the cytosol, transmembrane potential (ΔΨm) dissipation, caspase 9 and caspase 3 activation and DNA fragmentation. WFA cytotoxicity requires early reactive oxygen species (ROS) production and glutathione depletion, the inhibition of ROS increase by the antioxidant N-acetylcysteine resulting in complete suppression of mitochondrial and nuclear events. Altogether, these results support the therapeutic potential of WFA against human melanoma.

Molecular events involved in ochratoxin A induced mitochondrial pathway of apoptosis, modulation by Bcl-2 family members.

In this study, we looked for the role of the mitochondrion in the cytotoxicity of ochratoxin A (OTA), which is one of the most abundant food-contaminating mycotoxins in the world. In different human carcinoma cell lines, OTA triggered a mitochondria-dependent apoptotic process, which is characterized by opening of the mitochondrial permeability transition pore (PTPC), loss of mitochondrial transmembrane potential (ΔΨ(m) ), increase in O(2) [chemp](-) production, mitochondrial relocalization of Bax, release of cytochrome c, and caspase activation. However, studies performed on purified organelles suggested that OTA does not directly target the mitochondrion. In addition, we showed that mitochondrial alterations induced by this mycotoxin are favored by the proapoptotic protein Bax, but not Bak. These alterations are prevented by the antiapoptotic proteins, Bcl-2 and to a lesser degree by Bcl-X(L). Taken together, these data indicate that although mitochondria, PTPC members and proteins of Bcl-2 family play a pivotal role in OTA-induced apoptosis, they do not constitute real targets to overcome its toxicity.

Glutathionylation of adenine nucleotide translocase induced by carbon monoxide prevents mitochondrial membrane permeabilization and apoptosis.

The present work demonstrates the ability of CO to prevent apoptosis in a primary culture of astrocytes. For the first time, the antiapoptotic behavior can be clearly attributed to the inhibition of mitochondrial membrane permeabilization (MMP), a key event in the intrinsic apoptotic pathway. In isolated non-synaptic mitochondria, CO partially inhibits (i) loss of potential, (ii) the opening of a nonspecific pore through the inner membrane, (iii) swelling, and (iv) cytochrome c release, which are induced by calcium, diamide, or atractyloside (a ligand of ANT). CO directly modulates ANT function by enhancing ADP/ATP exchange and prevents its pore-forming activity. Additionally, CO induces reactive oxygen species (ROS) generation, and its prevention by beta-carotene decreases CO cytoprotection in intact cells as well as in isolated mitochondria, revealing the key role of ROS. On the other hand, CO induces a slight increase in mitochondrial oxidized glutathione, which is essential for apoptosis modulation by (i) delaying astrocytic apoptosis, (ii) decreasing MMP, and (iii) enhancing ADP/ATP translocation activity of ANT. Moreover, CO and GSSG trigger ANT glutathionylation, a post-translational process regulating protein function in response to redox cellular changes. In conclusion, CO protects astrocytes from apoptosis by preventing MMP, acting on ANT (glutathionylation and inhibition of its pore activity) via a preconditioning-like process mediated by ROS and GSSG.

The fourth isoform of the adenine nucleotide translocator inhibits mitochondrial apoptosis in cancer cells.

The adenine nucleotide translocator (ANT) is a mitochondrial bi-functional protein, which catalyzes the exchange of ADP and ATP between cytosol and mitochondria and participates in many models of mitochondrial apoptosis. The human adenine nucleotide translocator sub-family is composed of four isoforms, namely ANT1-4, encoded by four nuclear genes, whose expression is highly regulated. Previous studies have revealed that ANT1 and 3 induce mitochondrial apoptosis, whereas ANT2 is anti-apoptotic. However, the role of the recently identified isoform ANT4 in the apoptotic pathway has not yet been elucidated. Here, we investigated the effects of stable heterologous expression of the ANT4 on proliferation, mitochondrial respiration and cell death in human cancer cells, using ANT3 as a control of pro-apoptotic isoform. As expected, ANT3 enhanced mitochondria-mediated apoptosis in response to lonidamine, a mitochondriotoxic chemotherapeutic drug, and staurosporine, a protein kinase inhibitor. Our results also indicate that the pro-apoptotic effect of ANT3 was accompanied by decreased rate of cell proliferation, alteration in the mitochondrial network topology, and decreased reactive oxygen species production. Of note, we demonstrate for the first time that ANT4 enhanced cell growth without impacting mitochondrial network or respiration. Moreover, ANT4 differentially regulated the intracellular levels of hydrogen peroxide without affecting superoxide anion levels. Finally, stable ANT4 overexpression protected cancer cells from lonidamine and staurosporine apoptosis in a manner independent of Bcl-2 expression. These data highlight a hitherto undefined cytoprotective activity of ANT4, and provide a novel dichotomy in the human ANT isoform sub-family with ANT1 and 3 isoforms functioning as pro-apoptotic while ANT2 and 4 isoforms render cells resistant to death inducing stimuli.

GD3-7-aldehyde is an apoptosis inducer and interacts with adenine nucleotide translocase.

We prepared GD3-7-aldehyde (GD3-7) and determined its apoptotic potential. GD3-7 proved to be more efficient to induce pro-apoptotic mitochondrial alterations than GD3 when tested on mouse liver mitochondria. GD3-7-induced mitochondrial swelling and depolarization was blocked by cyclosporin A (CsA) supporting a critical role of the permeability transition pore complex (PTPC) during GD3-7-mediated apoptosis. In contrast to GD3, GD3-7 was able to induce channel formation in proteoliposomes containing adenine nucleotide translocase (ANT). This suggests that ANT is the molecular target of GD3-7. Using a specific antiserum, GD3-7 was detected in the lipid extract of the myeloid tumor cell line HL-60 after apoptosis induction, but not in living cells. Therefore, GD3-7 might be a novel mediator of PTPC-dependent apoptosis in cancer cells.

A novel point mutation in the CYBB gene promoter leading to a rare X minus chronic granulomatous disease variant--impact on the microbicidal activity of neutrophils.

This article reports an atypical and extremely rare case of X-linked CGD in an Italian family characterized by a low expression of gp91phox (X91- CGD). A novel point mutation in the CYBB gene's promoter (insertion of a T at position -54T to -56T) appeared to prevent the full expression of this gene in the patient's neutrophils and correlated with a residual oxidase activity in the whole cells population. The expression and functional activity of the oxidase in eosinophils appeared to be almost normal. Gel shift assays indicated that the mutation led to decreased interactions with DNA-binding proteins. The total O2- production in the patient's granulocytes (5-7% of normal) supported no microbicidal power after 45 min and 60 min of contact with S. aureus and C. albicans, respectively. Despite this residual oxidase activity, the patients suffered from severe and life-threatening infections. It was concluded that in these X91- CGD neutrophils, the O2- production per se was not sufficient to protect the patient against severe infections.

Fusarial toxin-induced toxicity in cultured cells and in isolated mitochondria involves PTPC-dependent activation of the mitochondrial pathway of apoptosis.

Mycotoxins produced by the Fusarium molds can cause a variety of human diseases and economic losses in livestock. Fusaria produce predominantly two types of mycotoxins: the nonestrogenic trichothecenes including T-2 toxin and the mycoestrogens such as zearalenone (ZEN). In a previous report, we demonstrated that the hepatotoxicity of these mycotoxins involves the mitochondrial pathway of apoptosis. Here, we observed that both fusarotoxins induced cell death by a mitochondria-dependent apoptotic process which includes opening of the mitochondrial permeability transition pore complex (PTPC), loss of mitochondrial transmembrane potential, increase in O(2)(.-) production, mitochondrial relocalization of Bax, cytochrome c release, and caspase activation. Studies performed on isolated mouse liver mitochondria showed that both ZEN and T-2 toxin might act directly on mitochondria to induce a PTPC-dependent permeabilization of mitochondrial membranes. Moreover, they may target different members of PTPC. Indeed, although the inner membrane protein adenine nucleotide translocase could be the target of T-2 toxin, ZEN seems to target the outer membrane protein voltage-dependent anion channel. Cells pretreatment with the p53 inhibitor pifithrin-alpha suggested that ZEN but not T-2 toxin triggered a p53-dependent mitochondrial apoptotic pathway. Finally, mitochondrial alterations induced by ZEN and T-2 toxin are mediated by Bcl-2 family proteins, such as Bax, and prevented by Bcl-x(L) and to a lesser extent by Bcl-2. Taken together, these data indicate that mitochondria play a pivotal role in both ZEN- and T-2 toxin-induced apoptosis and that PTPC members and proteins of Bcl-2 family should be interesting targets to overcome fusarotoxin toxicity.

First report of clinical, functional, and molecular investigation of chronic granulomatous disease in nine Jordanian families.

INTRODUCTION: Chronic granulomatous disease is a rare inherited immunodeficiency syndrome caused by mutations in four genes encoding essential nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex components. MATERIAL AND METHODS: Clinical, functional, and molecular investigations were conducted in 15 Jordanian CGD patients from nine families. RESULTS AND DISCUSSION: Fourteen patients were children of consanguineous parents and suffered from autosomal recessive (AR) CGD forms with mutations in the CYBA, NCF1, and NCF2 genes encoding p22phox, p47phox, and p67phox proteins, except for one patient in whom the mutation's location was not found. One patient had an extremely rare X(+)CGD subtype resulting from a novel missense mutation (G1234C) in exon 10 of CYBB. We found a genetic heterogeneity in the Jordanian families with a high frequency of rare ARCGD, probably because consanguineous marriages are common in Jordan. No clear correlation between the severity of the clinical symptoms and the CGD types could be established.

Mitoparan and target-selective chimeric analogues: membrane translocation and intracellular redistribution induces mitochondrial apoptosis.

Mastoparan, and structurally-related amphipathic peptides, may induce cell death by augmentation of necrotic and/or apoptotic pathways. To more precisely delineate cytotoxic mechanisms, we determined that [Lys(5,8)Aib(10)]mastoparan (mitoparan) specifically induces apoptosis of U373MG and ECV304 cells, as demonstrated by endonuclease and caspase-3 activation and phosphatidylserine translocation. Live cell imaging confirmed that, following translocation of the plasma membrane, mitoparan specifically co-localizes with mitochondria. Complementary studies indicated that mitoparan induces swelling and permeabilization of isolated mitochondria, through cooperation with a protein of the permeability transition pore complex VDAC, leading to the release of the apoptogenic factor, cytochrome c. N-terminal acylation of mitoparan facilitated the synthesis of chimeric peptides that incorporated target-specific address motifs including an integrin-specific RGD sequence and a Fas ligand mimetic. Significantly, these sychnologically-organised peptides demonstrated further enhanced cytotoxic potencies. We conclude that the cell penetrant, mitochondriotoxic and apoptogenic properties of mitoparan, and its chimeric analogues, offer new insights to the study and therapeutic induction of apoptosis.

Characterization of six novel mutations in the CYBB gene leading to different sub-types of X-linked chronic granulomatous disease.

Chronic granulomatous disease is an inherited disorder in which phagocytes lack a functional NADPH oxidase and so cannot generate superoxide anions (O(2) (-)). The most common form is caused by mutations in CYBB encoding gp91 phox, the heavy chain of flavocytochrome b(558) (XCGD). We investigated 11 male patients and their families suspected of suffering from X-linked CGD. These XCGD patients were classified as having different variants (X91(0), X91(-) or X91(+)) according to their cytochrome b(558) expression and NADPH oxidase activity. Nine patients had X91(0) CGD, one had X91(-) CGD and one had X91(+) CGD. Six mutations in CYBB were novel. Of the four new X91(0) CGD cases, three were point mutations: G65A in exon 2, G387T in exon 5 and G970T in exon 9, leading to premature stop codons at positions Try18, Try125 and Glu320, respectively, in gp91 phox. One case of X91(0) CGD originated from a new 1005G deletion detected in exon 9. Surprisingly, four nonsense mutations in exon 5 led to the generation of two mRNAs, one with a normal size containing the mutation and the other in which exon 5 had been spliced. A novel X91(-) CGD case with low gp91 phox expression was diagnosed. It was caused by an 11-bp deletion in the linking region between exon 12 and intron 12, activating a new cryptic site. Finally, a new X91(+) CGD case was detected, characterized by a missense mutation Leu505Arg in the potential NADPH-binding site of gp91 phox. No clear correlation between the severity of the clinical symptoms and the sub-type of XCGD could be established.