Mitoparans: mitochondriotoxic cell penetrating peptides and novel inducers of apoptosis.

Acknowledgments The authors would like to thank Keith Holding at the University of Wolverhampton for his outstanding technical support. This work was supported in part by Samantha Dickson Brain Tumour Trust.Introduction: The amphipathic helical peptide mastoparan (MP; H-INLKALAALAKKIL-NH2) inserts into biological membranes to modulate the activity of heterotrimeric G proteins and other targets. Moreover, whilst cell free models of apoptosis demonstrate MP to facilitate mitochondrial permeability transition and release of apoptogenic cytochrome c, MP-induced death of intact cells has been attributed to its non-specific membrane destabilising properties (necrotic mechanisms). However, MP and related peptides are known to activate other signalling systems, including p42/p44 MAP kinases and could therefore, also modulate cell fate and specific apoptotic events. The ability of MP to facilitate mitochondrial permeability in cell free systems has lead to proposals that MP could be of utility in tumour therapeutics provided that it conferred features of cellular penetration and mitochondrial localization. We have recently reported that our highly potent amphipathic MP analogue mitoparan (mitP; [Lys5,8Aib10]MP; Aib = -aminoisobutyric acid) specifically promotes apoptosis of human cancer cells, as was confirmed by in situ TUNEL staining and activation of caspase-3. Moreover, we have also demonstrated that mitP penetrates plasma membranes and redistributes to co-localize with mitochondria. Complementary studies, using isolated mitochondria, further demonstrated that mitP, through co-operation with a protein of the permeability transition pore complex voltage-dependent anion channel (VDAC), induced swelling and permeabilization of mitochondria, leading to the release of the apoptogenic factor cytochrome c. An expanding field of peptide and cell penetrating peptide (CPP) research has focussed on the selective targeting of tumours by engineering constructs that incorporate cell-specific or tissue–specific address motifs. Peptidyl address motifs could enhance the selectivity of drug delivery whilst the improved cellular uptake offered by CPP enhances bioavailability. Thus and as a potential therapeutic strategy, we extended our findings to design target-specific mitP analogues. The integrin-specific address motif RGD and a Fas ligand mimetic WEWT were incorporated by N-terminal acylation of mitP to produce novel tandem-linked chimeric peptides

Design and Synthesis of Thiazolo[5,4-f]quinazolines as DYRK1A Inhibitors, Part I

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Analysis of HIV Protease Killing Through Caspase 8 Reveals a Novel Interaction Between Caspase 8 and Mitochondria

Human Immunodeficiency Virus (HIV) protease initiates apoptosis of HIV-infected cells by proteolytic cleavage of procaspase 8, creating a novel peptide termed casp8p41. Expression of casp8p41 alone is sufficient to initiate caspase-dependent cell death associated with mitochondrial depolarization. Since casp8p41 does not contain the catalytic cysteine at position 360, the mechanism by which casp8p41 initiates apoptosis is unclear. We demonstrate that casp8p41 directly causes mitochondrial depolarization and release of cytochrome c with downstream caspase 9 activation. Moreover, death induced by casp8p41 requires the presence of mitochondria, and in intact cells, casp8p41 colocalizes with mitochondria. These results illuminate a novel mechanism of cell death induced by a caspase 8 cleavage fragment whereby mitochondrial interaction leads to depolarization and cytochrome c release

Synthesis and biological evaluation of new thiazolo [5,4-f]quinazolines as serine/threonine kinases inhibitors

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Design and Synthesis of Thiazolo[5,4-f]quinazolines as DYRK1A Inhibitors, Part II

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An Unusual Binding Model of the Methyl 9‑Anilinothiazolo[5,4‑<i>f</i>] quinazoline-2-carbimidates (EHT 1610 and EHT 5372) Confers High Selectivity for Dual-Specificity Tyrosine Phosphorylation-Regulated Kinases

Methyl 9-anilinothiazolo­[5,4-<i>f</i>]­quinazoline-2-carbimidates <b>1</b> (EHT 5372) and <b>2</b> (EHT 1610) are strong inhibitors of DYRK’s family kinases. The crystal structures of the complex revealed a noncanonical binding mode of compounds <b>1</b> and <b>2</b> in DYRK2, explaining the remarkable selectivity and potency of these inhibitors. The structural data and comparison presented here provide therefore a template for further improvement of this inhibitor class and for the development of novel inhibitors selectively targeting DYRK kinases

A modelling chain combining soft and hard models to assess a bundle of ecosystem services provided by a diversity of cereal-legume intercrops

International audienceCereal-legume intercropping is known to improve the sustainability of crop production. However, it remains uncommon on commercial farms in Europe due to a number of socio-technical lock-ins and the many practical issues raised when integrating intercrops in cropping systems (e.g. which species, cultivars, sowing densities). Crop modelling is an option to explore integration scenarios and support farmers' decisions. However, available crop models are not able to simulate bundles of ecosystem services provided by a large diversity of binary cereallegume intercropping scenarios. To address this challenge, we developed a hybrid modelling chain that combines process-based, statistical and knowledge-based models to benefit from the strengths of these three different modelling approaches. The chain (i) simulates potential biomass of the sole cereal and legume crops independently using the crop model STICS; (ii) uses statistical interaction models built in R to convert potential biomass in sole cropping into attainable biomass in intercropping by considering competition effects among species, using a field trial database; (iii) converts attainable biomass into actual biomass by considering pest damage using a knowledge-based multi-attribute DEXi model, and also assesses control of pests (i.e. weeds, insects and diseases); and (iv) uses another set of multi-attribute models to assess five additional ecosystem services (i.e. cereal and legume grain yields, cereal protein content, nitrogen supply to the following crop and impact on soil structure) from the actual biomass of the intercrop at harvest and/or cropping system features. The chain was calibrated for grain cereal-legume intercrops sown simultaneously in a random pattern under low-input French conditions. We used an expert-based approach to assess the performances of each model and evaluate the accuracy of the entire modelling chain. In 18 simulated scenarios, 79% of the predicted levels of ecosystem services were consistent with experts' opinion. Predictions were more accurate for intercropping scenarios that included species from the trial database used to build linear interaction models (relative RMSE of 27-31%) but remained satisfactory for other intercropped species (relative RMSE of 32-37%). This is the first modelling chain able to assess bundles of ecosystem services provided by multiple cereal-legume intercrops in function of their cropping system contexts. This chain is intended to be included in an educational tool that is used face to face with farmers or students to design cropping systems that include intercrops

<i>Bacillus cereus</i>, a serious cause of nosocomial infections: Epidemiologic and genetic survey

<div><p><i>Bacillus cereus</i> is the 2^nd most frequent bacterial agent responsible for food-borne outbreaks in France and the 3^rd in Europe. In addition, local and systemic infections have been reported, mainly describing individual cases or single hospital setting. The real incidence of such infection is unknown and information on genetic and phenotypic characteristics of the incriminated strains is generally scarce. We performed an extensive study of <i>B</i>. <i>cereus</i> strains isolated from patients and hospital environments from nine hospitals during a 5-year study, giving an overview of the consequences, sources and pathogenic patterns of <i>B</i>. <i>cereus</i> clinical infections. We demonstrated the occurrence of several hospital-cross-contaminations. Identical <i>B</i>. <i>cereus</i> strains were recovered from different patients and hospital environments for up to 2 years. We also clearly revealed the occurrence of inter hospital contaminations by the same strain. These cases represent the first documented events of nosocomial epidemy by <i>B</i>. <i>cereus</i> responsible for intra and inter hospitals contaminations. Indeed, contamination of different patients with the same strain of <i>B</i>. <i>cereus</i> was so far never shown. In addition, we propose a scheme for the characterization of <i>B</i>. <i>cereus</i> based on biochemical properties and genetic identification and highlight that main genetic signatures may carry a high pathogenic potential. Moreover, the characterization of antibiotic resistance shows an acquired resistance phenotype for rifampicin. This may provide indication to adjust the antibiotic treatment and care of patients.</p></div

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