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Introduction Functional blood vessels are of vital importance. Impaired vessel formation contributes to many pathological situations, including ischemic and inflammatory disorders. Ischemic retinopathies are the main causes of severe visual [...], During developmental angiogenesis, blood vessels grow and remodel to ultimately build a hierarchical vascular network. Whether, how, cell death signaling molecules contribute to blood vessel formation is still not well understood. Caspase-8 (Casp-8), a key protease in the extrinsic cell death-signaling pathway, regulates cell death via both apoptosis and necroptosis. Here, we show that expression of Casp-8 in endothelial cells (ECs) is required for proper postnatal retina angiogenesis. EC-specific Casp-8-KO pups (Casp-[8.sup.ECKO]) showed reduced retina angiogenesis, as the loss of Casp-8 reduced EC proliferation, sprouting, and migration independently of its cell death function. Instead, the loss of Casp-8 caused hyperactivation of p38 MAPK downstream of receptor-interacting serine/threonine protein kinase 3 (RIPK3) and destabilization of vascular endothelial cadherin (VE-cadherin) at EC junctions. In a mouse model of oxygen-induced retinopathy (OIR) resembling retinopathy of prematurity (ROP), loss of Casp-8 in ECs was beneficial, as pathological neovascularization was reduced in Casp-[8.sup.ECKO] pups. Taking these data together, we show that Casp-8 acts in a cell death-independent manner in ECs to regulate the formation of the retina vasculature and that Casp-8 in ECs is mechanistically involved in the pathophysiology of ROP.

Introduction Seasonal hibernation is a survival strategy used by a wide variety of mammals to survive extreme environmental changes in temperature and (or) food and water availability. Under unfavorable environmental [...], Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are excellent models for studying acute brain ischemia because they show high resistance to reductions in blood flow and oxygen delivery without evidence of neurological damage. In this study, we analyzed the insulin signaling pathway and regulation of mitochondrial substrate oxidation in three regions of ground squirrel brain (forebrain, cerebellum, and brainstem), comparing summer, late torpor, and interbout arousal conditions. We found select decreases in phospho-Akt in the cerebellum during torpor compared with summer animals, as well as select increases in the forebrain during interbout arousal, suggesting that Akt may influence either metabolism or cytoprotective pathways. The phosphoprotein abundance of glycogen synthase kinase 3 beta (GSK3[beta]) showed the most consistent trend across all three brain regions, with peak increases observed during deep torpor, suggesting a crucial role for this protein during hibernation. Furthermore, all three regions of the brain showed increased phospho-protein abundance of pyruvate dehydrogenase at serine 232 during both deep torpor and interbout arousal, and serine 300 during interbout arousal only, whereas other phosphorylation sites showed a region-specific expression pattern. Information collected from these studies sheds light on the molecular controls governing insulin signaling and fuel utilization in the brain of hibernating ground squirrels. Key words: hibernation, insulin signaling, protein translation, fat metabolism, glycolysis. Le spermophile rayé (Ictidomys tridecemlineatus) constitue un excellent modèle pour étudier l'ischémie cérébrale aigüe, car il est très résistant à des réductions du flux sanguin et de l'oxygénation sans manifestations d'un dommage neurologique. Dans cette étude, les auteurs ont analysé la voie de signalisation de l'insuline et la régulation de l'oxydation des substrats mitochondriaux dans trois régions du cerveau du spermophile (cerveau antérieur, cervelet et tronc cérébral) en comparant les conditions d'été, de torpeur tardive et d'éveil périodique. Ils ont trouvé des diminutions sélectives de phospho-Akt dans le cervelet durant la période de torpeur comparativement à l'été, de même que des augmentations sélectives dans le cerveau antérieur durant l'éveil périodique, suggérant que Akt puisse influencer le métabolisme ou les voies de protection cellulaire. À travers l'abondance de la forme phosphorylée de GSK3[beta] se dessinait la tendance la plus persistante à travers les trois régions du cerveau, avec des augmentations de pointe durant la torpeur profonde, suggérant que cette protéine jouerait un rôle important durant l'hibernation. En outre, l'abondance de la forme phosphorylée de la pyruvate déshydrogénase sur la sérine 232 était accrue dans les trois régions du cerveau durant la torpeur profonde et l'éveil périodique, la phosphorylation sur la sérine 300 était accrue durant l'éveil périodique seulement, alors que les sites de phosphorylation montraient un patron d'expression spécifique à la région. L'information recueillie lors de ces études fait la lumière sur les mécanismes de contrôle moléculaires qui gouvernent la signalisation et l'utilisation de carburant dans le cerveau des spermophiles en hibernation. [Traduit par la Rédaction] Mots-clés: hibernation, signalisation de l'insuline, traduction des protéines, métabolisme des lipides, glycolyse.

RA signaling Retinoic acid (RA) is the main derivative of vitamin A. After entering the cell, RA binds and activates the nuclear receptors retinoic acid receptor (RAR) and retinoic X [...], Retinoic acid (RA) signaling is involved in various physiological and pathological conditions, including development, tumorigenesis, inflammation, and tissue damage and repair. In kidneys, the beneficial effect of RA has been reported in multiple disease models, such as glomerulosclerosis, renal fibrosis, and acute kidney injury. In this issue of the JCI, Chen et al. report a pathway activated by RA signaling that is mediated by the retinoic acid receptor responder protein 1 (RARRES1). Specifically, RARRES1, which is proteolytically cleaved to release the extracellular domain, was endocytosed by podocytes to induce apoptosis and glomerular dysfunction kidney disease. These findings unveil the contrasting aspects, a Janus face, of RA signaling that may guide its therapeutic use.

Introduction Caspases belong to an evolutionarily conserved family of 14 cysteine aspartyl-specific proteases that initiate and induce signaling pathways for apoptotic cell death, inflammation, and cell differentiation (Earnshaw et al. [...], Procaspase-7 zymogen polypeptide is composed of a short prodomain, a large subunit (p20), and a small subunit (p10) connected to an intersubunit linker. Caspase-7 is activated by an initiator caspase-8 and -9, or by autocatalysis after specific cleavage at [IQAD.sup.198][down arrow]S located at the intersubunit linker. Previously, weidentified that PEST regions made of amino acid residues Pro (P), Glu (E), Asp (D), Ser (S), Thr (T), Asn (N), and Gln (Q) are conserved flanking amino acid residues in the cleavage sites within a prodomain and intersubunit linker of all caspase family members. Here we tested the impact of alanine substitution of PEST amino acid residues on procaspase-7 proteolytic self-activation directly in Escherichia coli. The p20 and p10 subunit cleavage were significantly delayed in double caspase-7 mutants in the prodomain (N18A/P26A) and intersubunit linker (S199A/P201A), compared with the wild-type caspase-7. The S199A/P201A mutants effectively inhibited the p10 small subunit cleavage. However, the mutations did not change the kinetic parameters ([k.sub.cat]/[K.sub.M]) and optimal tetrapeptide specificity (DEVD) of the purified mutant enzymes. The results suggest a role of PEST-amino acid residues in the molecular mechanism for prodomain and intersubunit cleavage and caspase-7 self-activation. Key words: apoptosis, caspases, PEST motif, protease activation mechanism. Resume:Lepolypeptide zymogene procaspase-7 est forme d'un court pro-domaine, d'une grande sous-unite (p20)etd'une petite sous-unite (p10) liees par un connecteur inter-domaine. La caspase-7 est activee par les caspases initiatrices-8 et -9 ou par autocatalyse a la suite du clivage specifique a la position [IQAD.sup.198][down arrow]S localisee dans le connecteur inter-domaine. Precedemment, les auteurs avaient montre que des regions PEST faites des acides amines Pro (P), Glu (E), Asp (D), Ser (S), Thr (T), Asn (N), et Gln (Q) sont des residus d'acides amines conserves flanquant les sites de clivage a l'interieur du pro-domaine et du connecteur inter-domaine chez tous les membres de la famille des caspases. Ils ont teste ici l'impact d'une substitution par une alanine d'acides amines des regions PEST sur l'auto-activation proteolytique de la procaspase-7 directement chez Escherichia coli. Le clivage des sous-unites p20 et p10 etait significativement retarde significativement chez les doubles mutants du pro-domaine (N18A/P26A) et du connecteur inter-domaine (S199A/P201A) de la caspase-7 comparativement a la caspase-7 sauvage. Les mutations S199A/P201A inhibaient effectivement le clivage de la petite sous-unite p10. Cependant, les mutations n'affectaient pas les parametres cinetiques ([k.sub.cat]/[K.sub.M]) et la specificite optimale pour le tetra-peptide (DEVD) de l'enzyme mutante purifiee. Les resultats suggerent que les acides amines PEST jouent un role dans le mecanisme moleculaire du clivage du pro-domaine et entre les sous-unites, et dans l'auto-activation de la caspase-7. [Traduit par la Redaction] Mots-cles : apoptose, caspases, motif PEST, mecanisme d'activation.

Introduction Osteoarthritis (OA) (Soder et al. 2006) is a common joint disease accompanied with pain and disability, and about 15% of the world's population suffers from OA (Huskisson 2008). OA [...], Danshen (Salvia miltiorrhiza) is a traditional Chinese medicine herb that can alleviate the symptoms of osteoarthritis (OA) (Soder et al. 2006) in animals. However, the underlying mechanisms remain poorly understood and require further investigation. In this study, rabbits with experimentally induced OA were given an intra-articular injection of danshen (0.7 mL/day) for 5 weeks. In addition to attenuating the cartilage degeneration of OA in the rabbits, danshen decreased the expression and activity of matrix metalloproteinase 9 (MMP-9) and MMP-13, and increased the expression of their natural inhibitors: tissue inhibitor of matrix metalloproteinase 1 (TIMP-1) and TIMP-2. Apoptosis in osteoarthritic cartilage tissues was attenuated by danshen, accompanied with increased expression of B cell lymphoma 2 (Bcl-2) and decreased levels of Bcl-2-associated X protein (Bax). Further, danshen inhibited the nuclear accumulation of nuclear factor kappa-B (NF-[kappa]B) p65 in osteoarthritic cartilage. The therapeutic effects of danshen in vivo were comparable to that of sodium hyaluronate, which is a drug used clinically for the treatment OA. In vitro, sodium nitroprusside (SNP) was used to stimulate apoptosis in primary rabbit chondrocytes. We found that the SNP-induced apoptosis was mitigated by danshen. BAY11-7028, an inhibitor of the NF-[kappa]B pathway, augmented danshen's anti-apoptotic effects in cells exposed to SNP. When these results are considered together, they indicate that danshen alleviates the cartilage injury in rabbit OA through inhibition of the NF-[kappa]B signaling pathway. Key words: osteoarthritis, danshen, cartilage degradation, apoptosis, NF-[kappa]B signaling pathway. Resume : Le danshen est une herbe medicinale traditionnelle chinoise qui peut soulager les symptomes de l'osteoarthrite (OA) chez l'animal (Soder et al. 2006). Cependant, les mecanismes sous-jacents demeurent peu compris et necessitent d'etre etudies davantage. Dans cette etude, des lapins ayant developpe une OA experimental ont recu une injection intra-articulaire de danshen (0.7 mL/jour) pendant 5 semaines. En plus d'attenuer la degenerescence du cartilage chez les lapins O.A., le danshen diminuait l'expression et l'activite de la metalloprotease matricielle 9 (MMP-9) et de MMP-13, alors qu'il augmentait celles de leurs inhibiteurs naturels, l'inhibiteur tissulaire des MMP1 (TIMP-1) et TIMP-2. L'apoptose des tissus du cartilage osteo-arthritique etait attenuee par le danshen, ce qui etait accompagne de l'augmentation de l'expression de Bcl-2 (B cell lymphoma 2) et d'une diminution de l'expression de Bax (Bcl-2-associated X protein). De plus, le danshen inhibait l'accumulation nucleaire de la sous-unite p65 du facteur nucleaire kappa-B (NF-[kappa]B) dans les cartilages osteo-arthritiques. Les effets therapeutiques du danshen in vivo etaient comparables a ceux de l'hyaluronate de sodium, un medicament utilise en clinique pour l'OA In vitro, le nitroprussiate de sodium (SNP) a ete utilise pour stimuler l'apoptose de chondrocytes primaires de lapin. Les auteurs ont trouve que l'apoptose induite par le SNP etait attenuee par le danshen. Le BAY11-7028, un inhibiteur de la voie du NF-[kappa]B, accroissait les effets anti-apoptotiques du danshen chez les cellules exposees au SNP. Globalement, le danshen attenue le dommage au cartilage cause par l'OA chez les lapins, au moins par l'inhibition de la voie de signalisation du NF-[kappa]B. [Traduit par la Redaction] Mots-cles: osteoarthrite, danshen, degradation du cartilage, apoptose, voie de signalisation du NF-[kappa]B.

Introduction Euphorbia (spurge) belongs to the Euphorbiaceae family, one of the largest families in the plant kingdom, and considered as the largest genus (over 2000 species) of this family (Ghanadian [...], We investigated the molecular mechanism of apoptosis induced by novel jatropha-6(17),11E-diene class derivatives, compounds A, B, and C that were extracted from Euphorbia osyridea Boiss, in the ovarian cancer cell lines Caov-4 and OVCAR-3. The OVCAR-3 and Caov-4 cell lines were treated with different concentrations of these compounds. Cytotoxicity was evaluated using MTT, clonogenic survival assay, and flow cytometry assays. The production of reactive oxygen species (ROS), mitochondrial membrane potential ([[DELTA].sub.[PSI]m]), and the activity of caspase 3 and 9 were evaluated. Compounds A, B, and C reduced cell viability in a dose-dependent manner (P < 0.05). The I[C.sub.50] values were calculated as 46.27 [+ or -] 3.86, and 38.81 [+ or -] 3.30 [mu]mol/L for compound A, 36.48 [+ or -] 3.18 and 42.59 [+ or -] 4.50 [mu]mol/L for compound B, and 85.86 [+ or -] 6.75 and 75.65 [+ or -] 2.56 [mu]mol/L for compound C against the Caov-4 and OVCAR-3 cell lines, respectively. Apoptosis evaluation showed that jatrophane derivatives increase both early and late apoptosis (P < 0.01). These compounds also increased ROS generation, [[DELTA].sub.[PSI]m], and the activity of caspase 3 and 9 in the treated cells. These results showed that compounds A and B have significant inhibitory effects on OVCAR-3 and Caov-4 proliferation and induction of apoptosis. Key words: jatrophane, Euphorbia, apoptosis, ovarian cancer. Resume : Les auteurs ont examine le mecanisme moleculaire de l&apos;apoptose induite par de nouveaux derives de la classe des jatropha-6(17), 11E-dienes, les composes A, B et C, extraits d&apos;Euphorbia osyridea Boiss dans les lignees cellulaires de cancer ovarien Caov-4 et OVCAR-3. Les lignees cellulaires Caov-4 et OVCAR-3 ont ete traitees avec differentes concentrations de ces composes. La cytotoxicite a ete evaluee par des tests au MTT, de survie clonogenique et par cytometrie en flux. La production de derives reactifs d&apos;oxygene (DRO), le potentiel membranaire mitochondrial ([[DELTA].sub.[PSI]m]) et l&apos;activite des caspase-3 et caspase-9 ont ete evalues. Les composes A, B et C reduisaient la viabilite cellulaire en fonction de leur concentration (P < 0,05). Les valeurs de C[I.sub.50] ont ete calculeesv a 46,27 [+ or -] 3,86 et 38,81 [+ or -] 3,30 [mu]mol/L pour le compose A, 36,48 [+ or -] 3,18 et 42,59 [+ or -] 4,50 [mu]mol/L pour le compose B et 85,86 [+ or -] 6,75 et 75,65 [+ or -] 2,56 [mu]mol/L pour le compose C envers les lignees cellulaires Caov-4 et OVCAR-3, respectivement. L&apos;evaluation de l&apos;apoptose a montre que les derives jatrophanes accroissaient l&apos;induction de l&apos;apoptose precoce et tardive (P < 0,01). Ces composes accroissaient aussi la generation de DRO, le [[DELTA].sub.[PSI]m] et l&apos;activation des caspase 3 et caspase 9 chez les cellules traitees. Ces resultats ont montre que les composes A et B ont des effets inhibiteurs significatifs de la proliferation des OVCAR-3 et Caov-4 et inducteurs de l&apos;apoptose. [Traduit par la Redaction] Mots-cles : jatrophane, Euphorbia, apoptose, cancer ovarien.

Introduction Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies around the world, having high morbidity and mortality. Currently, surgical resection and liver transplantation are the best options for [...], Esculetin (6,7-dihydroxycoumarin) is a coumarin derivative extracted from natural plants and has been reported to have anticancer activity. However, the mechanism by which esculetin prevents human hepatic cancer cell growth is still largely unknown. In this study, we investigated the effect of esculetin on human hepatocellular carcinoma (HCC) SMMC-7721 cells and explored the cell signal mechanism. Our data indicated that esculetin induced apoptosis in SMMC-7721 cells, which were supported by DAPI staining and Annexin V/PI staining. Meanwhile, esculetin increased the activities of caspase-3 and caspase-9, promoted bax expression, decreased bcl-2 expression, and triggered collapse of mitochondrial membrane potential, and increased cytochrome c release from mitochondria. In addition, the inactivation of IGF-1, PI3K, and Akt was observed after esculetin administration. Furthermore, pretreatment with IGF-1 before esculetin administration abrogated the pro-apoptotic effects of esculetin, while PI3K inhibitor increased the pro-apoptotic effects of esculetin. These results indicated that esculetin induced the apoptosis of SMMC-7721 cells through IGF-1/PI3K/Akt-regulated mitochondrial dysfunction. Key words: esculetin, hepatocellular carcinoma SMMC-7721 cells, apoptosis, IGF-1, mitochondria. L&apos;esculetine (6,7-dihydroxycoumarine) est un derive de la coumarine extrait de plantes naturelles, et pour laquelle on a rapporte une activite anticancereuse. Toutefois, le mecanisme par lequel l&apos;esculetine permet de prevenir la croissance des cellules cancereuses de foie humain demeure largement inconnu. Dans ces travaux, nous avons etudie l&apos;effet de l&apos;esculetine sur les cellules SMMC-7721 d&apos;hepatome chez l&apos;homme et explore le mode d&apos;action dans la signalisation cellulaire. Nos donnees ont montre que l&apos;esculetine induisait l&apos;apoptose dans les cellules SMMC-7721, ce que les colorations au DAPI et avec l&apos;annexine V/PI venaient appuyer. Concurremment, l&apos;esculetine entrainait l&apos;augmentation de l&apos;activite de la caspase-3 et de la caspase-9, favorisait l&apos;expression de la proteine bax, entrainait une diminution de l&apos;expression des genes bcl-2 et declenchait l&apos;effondrement du potentiel de la membrane mitochondriale avec une augmentation de la liberation de cytochrome c des mitochondries. De plus, nous avons observe l&apos;inactivation des facteurs IGF-1, PI3K et Akt apres l&apos;administration d&apos;esculetine. De surcroit, l&apos;exposition a l&apos;IGF-1 avant l&apos;administration d&apos;esculetine contrecarrait les effets proapoptotiques de l&apos;esculetine. Inversement, un inhibiteur du facteur PI3K augmentait les effets proapoptotiques de l&apos;esculetine. Ces resultats montraient que l&apos;esculetine induisait l&apos;apoptose des cellules SMMC-7721 par un dysfonctionnement des mitochondries dont la regulation etait assuree par la voie de signalisation IGF-1/PI3K/Akt. [Traduit par la Redaction] Mots-cles: esculetine, cellules SMMC-7721 d&apos;hepatome, apoptose, IGF-1, mitochondrie.

Author(s): Thuan Beng Saw [1, 2]; Amin Doostmohammadi [3]; Vincent Nier [4]; Leyla Kocgozlu [1]; Sumesh Thampi [3, 5]; Yusuke Toyama [1, 6, 7]; Philippe Marcq [4]; Chwee Teck Lim [...]