Mitosis is a critically important and time sensitive cellular process that proceeds rapidly, typically completing in 15-45 minutes. Mechanisms have evolved to measure the duration of mitosis, resulting in the identification of aberrant cells that spend too long in mitosis. If non-transformed cells undergo a mitosis that exceeds 90 minutes, then the resulting daughter cells activate a durable G1 arrest and cease proliferating. The underlying mechanism acting to time the duration of mitosis is unknown. Here, we demonstrate that cells activate the Hippo pathway upon entry into mitosis, which initiates degradation of the pro-growth transcriptional co-activators YAP and TAZ. Consequently, prolonged mitosis leads to decreased YAP/TAZ levels in the following G1, thus enforcing cell cycle arrest. We reveal that inactivation of the Hippo pathway, which is common in solid tumors, is sufficient to restore YAP/TAZ levels following a prolonged mitosis, and cells born from this prolonged mitosis can progress through the cell cycle. We also demonstrate that Hippo pathway inactivation alters cell fate decisions in response to mitotic arrest. Antimitotics (e.g. Taxol) have long been used to permanently arrest cells in mitosis, which frequently results in mitotic cell death. It has long been recognized that some cancer cells are resistant to antimitotics; this resistance can arise from cells escaping mitosis into the G1 phase in a process termed mitotic slippage. The mechanisms underlying these cell fate decisions are poorly understood. Here, we demonstrate that inactivation of the Hippo pathway promotes mitotic slippage and overall survival in cells treated with antimitotics by increasing antiapoptotic protein expression. Our data suggest that inactivation of the Hippo pathway may promote resistance to antimitotic therapies by favoring the survival and proliferation of cells that have experienced a prolonged mitosis. Interestingly, we find that restoring Hippo signaling to cancer cells that are resistant to antimitotic therapies sensitizes them to antimitotics and promotes mitotic cell death. Overall, we illuminate a broad role for Hippo signaling in determining cell fate during mitosis and identify a novel mechanism by which resistance to antimitotic therapies can arise. / 2020-10-24T00:00:00Z

Ataxia telangiectasia and Rad3-related protein (ATR) is a serine/threonine-protein kinase of the PI3K family and is well known for its key role in regulating DNA damage responses in the nucleus. In addition to its nuclear functions, ATR also was found to be a substrate of the prolyl isomerase Pin1 in the cytoplasm where Pin1 isomerizes cis ATR at the Ser428-Pro429 motif, leading to formation of trans ATR. Cis ATR is an antiapoptotic protein at mitochondria upon UV damage. Here we report that Pin1’s activity on cis ATR requires the phosphorylation of the S428 residue of ATR and describe the molecular mechanism by which Pin1-mediated ATR isomerization in the cytoplasm is regulated. We identified protein phosphatase 2A (PP2A) as the phosphatase that dephosphorylates Ser428 following DNA damage. The dephosphorylation led to an increased level of the antiapoptotic cis ATR (ATR-H) in the cytoplasm and, thus, its accumulation at mitochondria via binding with tBid. Inhibition or depletion of PP2A promoted the isomerization by Pin1, resulting in a reduction of cis ATR with an increased level of trans ATR. We conclude that PP2A plays an important role in regulating ATR’s anti-apoptotic activity at mitochondria in response to DNA damage. Our results also imply a potential strategy in enhancing cancer therapies via selective moderation of cis ATR levels.

Peptidyl-prolyl isomerization is an important post-translational modification of protein because proline is the only amino acid that can stably exist as cis and trans, while other amino acids are in the trans conformation in protein backbones. This makes prolyl isomerization a unique mechanism for cells to control many cellular processes. Isomerization is a rate-limiting process that requires a peptidyl-prolyl cis/trans isomerase (PPIase) to overcome the energy barrier between cis and trans isomeric forms. Pin1, a key PPIase in the cell, recognizes a phosphorylated Ser/Thr-Pro motif to catalyze peptidyl-prolyl isomerization in proteins. The significance of the phosphorylation-dependent Pin1 activity was recently highlighted for isomerization of ATR (ataxia telangiectasia- and Rad3-related). ATR, a PIKK protein kinase, plays a crucial role in DNA damage responses (DDR) by phosphorylating hundreds of proteins. ATR can form cis or trans isomers in the cytoplasm depending on Pin1 which isomerizes cis-ATR to trans-ATR. Trans-ATR functions primarily in the nucleus. The cis-ATR, containing an exposed BH3 domain, is anti-apoptotic at mitochondria by binding to tBid, preventing activation of pro-apoptotic Bax. Given the roles of apoptosis in many human diseases, particularly cancer, we propose that cytoplasmic cis-ATR enables cells to evade apoptosis, thus addicting cancer cells to cis-ATR formation for survival. But in normal DDR, a predominance of trans-ATR in the nucleus coordinates with a minimal level of cytoplasmic cis-ATR to promote DNA repair while preventing cell death; however, cells can die when DNA repair fails. Therefore, a delicate balance/equilibrium of the levels of cis- and trans-ATR is required to ensure the cellular homeostasis. In this review, we make a case that this anti-apoptotic role of cis-ATR supports oncogenesis, while Pin1 that drives the formation of trans-ATR suppresses tumor growth. We offer a potential, novel target that can be specifically targeted in cancer cells, without killing normal cells, to significantly reduce the adverse effects usually seen in cancer treatment. We also raise important issues regarding the roles of phosphorylation-dependent Pin1 isomerization of ATR in diseases and propose areas of future studies that would shed more understanding on this important cellular mechanism.

Diversos são os fatores que estão envolvidos no controle da maturação oocitária e na qualidade e competência do oócito. A melatonina (MEL) é um hormônio que apresenta diversas funções, como atividade antioxidante e antiapoptótica, além de influenciar diferentes vias de sinalização celular. Ainda há poucos estudos sobre o papel da MEL na maturação de oócitos e o camundongo, por sua rápida reprodução e menor custo de manutenção, é um excelente modelo amplamente utilizado para estudos in vitro e, particularmente in vivo. O presente trabalho teve por objetivo avaliar o efeito da MEL sobre a maturação in vivo e in vitro e sua possível ação como protetor celular (antioxidante e/ou antiapoptótico) de complexos cumulus-oócitos (CCOs) murinos. No experimento 1, os animais receberam injeções de MEL nas concentrações de 0 (controle), 10 e 20 mg/kg/i.p./dia por 4 dias. Os CCOs foram maturados in vivo e recuperados 17 horas após a última injeção. No experimento 2, os animais receberam MEL nas mesmas dosagens do experimento anterior, porém por 3 dias. Os CCOs foram coletados 24 horas após a última injeção e maturados in vitro com hormônio folículo estimulante (0,5 µg/mL; FSH). No experimento 3, os CCOs foram maturados in vitro na presença de três diferentes doses de MEL (10-9, 10-6 e 10-3 M) ou em FSH (controle FSH). Por fim, no experimento 4, a melhor concentração de MEL (10-9 M) eleita no experimento 3, foi utilizada sozinha ou em associação com peróxido de hidrogênio (300µM; H2O2). Os CCOs foram maturados como no experimento anterior. Para os quatro experimentos foram avaliados a taxa de maturação mediante a extrusão do primeiro corpúsculo polar (1º CP) e a expressão de genes relacionados à apoptose (Bax e Bcl2l1) e enzimas antioxidantes (Gpx1, Sod1 e Sod2) por qPCR-RT tanto para as células do cumulus (CC), quanto para os oócitos (OO). No experimento 1, o tratamento com 20 mg/kg de MEL apresentou maior taxa de maturação in vivo de 80,3%, seguido do controle (69,4%) e 10 mg/kg de melatonina (62,4%; P>0,05). Para a expressão gênica não houve efeito de nenhum tratamento (P>0,05). No experimento 2, a taxa de maturação variou de 39 a 53,2% entre os tratamentos (P>0,05). Em CC, a expressão gênica foi diminuída de Bcl2l1 e aumentada de Gpx1 tratados com 20 mg/kg de MEL (P<0,05). Já para OO, somente houve aumento da expressão de Gpx1 para ambos os tratamentos com MEL (P<0,05). No experimento 3, a taxa de maturação foi de 48,9%, 53,7%, 56% e 57,3% para 10-3, 10-6, 10-9 M de MEL e FSH, respectivamente (P>0,05). As concentrações de 10-9 e 10-6 M de MEL aumentaram a expressão dos genes Gpx1 e Sod1 em CC (P<0,05). Em OO, somente houve aumento da expressão gênica de Bax na concentração de 10-6 M de MEL (P<0,05). No último experimento, não houve diferença significativa quanto à taxa de maturação, variando de 51,8% para o tratamento com H2O2 a 60% para o controle FSH (P>0,05). Em CC, Gpx1 e Sod1 tiveram suas expressões aumentadas em todos os tratamentos (P<0,05). De maneira contrária, o gene Bcl2l1 teve sua expressão diminuída (P<0,05). Com base nestes dados, conclui-se que a MEL aplicada in vivo não foi capaz de melhorar a taxa de maturação in vivo e in vitro, porém, em condições in vitro induziu a progressão da meiose em oócitos murinos. Além disso, em condições in vitro, genes antioxidantes como Gpx1 e Sod1 foram mais expressos em CC do que em OO em resposta ao tratamento com MEL, indicando a indução de um possível efeito protetor frente à condições de cultivo in vitro. / Many factors are involved in the control of oocyte maturation and developmental competence. Melatonin (MEL) is a hormone showing varied functions including antioxidant and antiapoptotic activities, besides influencing many cell signaling pathways. There are few studies on the role of MEL in oocyte maturation and the mouse, due to its quick reproduction and lower maintencance cost, is an interesting model widely used for in vitro and particularly in vivo studies. The aim of this work was to study the effects of MEL on in vivo and in vitro maturation and its cytoprotective action (antioxidant/antiapoptotic) in murine cumulus-oocyte complexes (CCOs). In experiment one, mice received MEL injections at concentrations of 0 (control), 10 and 20 mg/kg/i.p./day for 4 days. CCOs were in vivo matured and recovered 17 hours after the last injection. In experiment 2, the animals received MEL in the same dosages of the previous experiment, but for 3 days. CCOs were collected 24 hours after the last injection and in vitro matured with follicle stimulating hormone (FSH). In experiment 3, CCOs were in vitro matured with three MEL concentrations (10-9, 10-6 e 10-3 M) or FSH (FSH control). Finally, in the fourth experiment, the best concentration of MEL (10-9 M) selected in experiment 3 was used alone or in association with hydrogen peroxide (300 µM; H2O2). CCOs were matured as in the previous experiment. For all four experiments maturation rates were evaluated by extrusion of the first polar body and the expression of genes related to apoptosis (Bax and Bcl2l1) and antioxidant enzymes (Gpx1, Sod1 and Sod2) by qPCR-RT both cumulus cells (CC), and for the oocytes (OO) were assessed as well. In experiment 1, treatment with 20 mg/kg MEL showed a higher rate of in vivo maturation of 80.3%, followed by the control (69.4%) and 10 mg/kg MEL (62.4%; P>0.05). No effect for gene expression treatments (P>0.05) was observed. In experiment 2, maturation rate ranged from 39 to 53.2% between treatments (P>0.05). In CC, the gene expression was reduced for Bcl2l1 and enhanced for Gpx1 in animals treated with 20 mg/kg MEL (P<0.05). For OO, only Gpx1 expression was increased for both MEL treatments (P<0.05). In experiment 3, the maturation rates were 48.9, 53.7, 56 e 57.3% for MEL 10-3, 10-6, 10-9 M and FSH, respectively (P>0.05). MEL concentrations of 10-6 and 10-9 M increased expression of Gpx1 and Sod1 genes in CC (P<0.05). For OO, only Bax increased the gene expression in 10-6 M MEL concentration (P<0.05). In the last experiment, there was no significant difference in maturation rate, ranging from 51.8 for H2O2 to 60% for FSH control (P>0.05). Gpx1 and Sod1 genes had their expression increased in all the treatments in CC (P<0.05). For Bcl2l1 gene, the expression was decreased in CC as well (P<0.05). Based on these data, we conclude that MEL treatment in vivo was unable to promote maturation rate in vivo and in vitro, but under in vitro conditions it induced meiosis progression in murine oocytes. In addition, Gpx1 and Sod1 antioxidant genes were more expressed in CC than OO in response to MEL treatments in vitro indicating induction of a possible protective effect against in vitro culture conditions.

A lagarta L. obliqua tem se destacado por apresentar em sua hemolinfa proteínas com atividade biológica demonstrada em cultivos celulares. A literatura disponível não apresenta trabalhos sobre a expressão da proteína antiapoptótica de L. obliqua, então este estudo objetiva a clonagem e expressão da proteína antiapoptótica presente na hemolinfa de L. obliqua, em sistema bacteriano Escherichia coli. O RNAm extraído do tegumento de L. obliqua deu origem a um cDNA obtido por RT-PCR, o qual foi clonado em vetor pCR II-TOPO para posterior transformação de bactérias E. coli JMQC. Na expressão heteróloga, o fragmento foi subclonado em vetor pET28a e transformadas bactérias E. coli BLQC. A indução de expressão foi realizada com IPTG 1 mM. A APLOrEC purificada por cromatografia foi identificada por Western Blot. A atividade biológica da APLOrE foi analisada em células VERO e L929 após indução de morte e verificou-se que esta protegeu os cultivos induzidos com 4mM de H2O2 portanto, eficaz na manutenção estrutural do citoesqueleto destas células. / The caterpillar L. obliqua has become known for performing in their hemolymph proteins with biological activity demonstrated in cell cultures. The available literature does not provide studies on the expression of antiapoptotic protein L. oblique, so this study aims cloning and expression of anti-apoptotic protein present in the hemolymph of L. oblique, bacterial system in Escherichia coli. The extracted mRNA L. obliqua husk gave a cDNA obtained by RT-PCR, which was cloned into pCR II-TOPO vector for subsequent transformation of E. coli bacteria JMQC. The heterologous expression, the fragment was subcloned into pET28a vector and transformed E. coli bacteria BLQC. The induction of expression was performed with 1 mM IPTG. The APLOrEC purified by chromatography was identified by Western blot. The biological activity was examined in APLOrE VERO and L929 cells after death induction, and it was found that this protected crops H2O2 induced with 4mM therefore effective in the structural maintenance of the cytoskeleton of such cells.

Les protéines de la famille Bcl-2 sont des régulateurs-clés de l’apoptose (mort cellulaire), qui agissent en contrôlant la perméabilisation de la membrane mitochondriale externe par un processus encore mal connu. La dérégulation des membres de cette famille est souvent associée à la progression tumorale et à la résistance à la chimiothérapie. Notre projet a cherché à éclaircir le mode d’action de ces protéines en se focalisant sur les déterminants structuraux régissant leur interaction avec les membranes biologiques. Les connaissances glanées ont permis (i) de mieux comprendre les déterminants à l’origine de la divergence évolutive entre membres pro- et anti-apoptotiques de la famille Bcl-2 ; (ii) d’ouvrir la voie à la conception de ‘poropeptides’ conçus sur le modèle des hélices d’insertion membranaire des protéines Bcl-2, et qui pourraient être utilisés pour induire l’apoptose de cellules tumorales ou des cellules endothéliales entourant les tumeurs. / Bcl-2 family proteins, which include pro- and antiapoptotic members, positively or negatively regulate mitochondrial outer membrane permeabilization, i.e. a critical step in apoptosis. Over-expression of pro-survival members is associated with tumor progression and may be responsible for chemotherapy resistance. Detailed understanding of the precise mechanisms by which Bcl-2 family members control apoptosis is therefore of considerable therapeutic interest. The overall aim of our project was to delineate a structure-function relationship of Bcl-2 family proteins with emphasis on their membrane-active domains. This analysis has provided a basis (i) to elucidate the molecular mechanisms by which different Bcl-2 proteins evolved opposite functions ; (i) to develop a new generation of pore-forming peptides targeting the mitochondrial outer membrane that may be used to kill neoplastic or tumor endothelial cells.

Diversos são os fatores que estão envolvidos no controle da maturação oocitária e na qualidade e competência do oócito. A melatonina (MEL) é um hormônio que apresenta diversas funções, como atividade antioxidante e antiapoptótica, além de influenciar diferentes vias de sinalização celular. Ainda há poucos estudos sobre o papel da MEL na maturação de oócitos e o camundongo, por sua rápida reprodução e menor custo de manutenção, é um excelente modelo amplamente utilizado para estudos in vitro e, particularmente in vivo. O presente trabalho teve por objetivo avaliar o efeito da MEL sobre a maturação in vivo e in vitro e sua possível ação como protetor celular (antioxidante e/ou antiapoptótico) de complexos cumulus-oócitos (CCOs) murinos. No experimento 1, os animais receberam injeções de MEL nas concentrações de 0 (controle), 10 e 20 mg/kg/i.p./dia por 4 dias. Os CCOs foram maturados in vivo e recuperados 17 horas após a última injeção. No experimento 2, os animais receberam MEL nas mesmas dosagens do experimento anterior, porém por 3 dias. Os CCOs foram coletados 24 horas após a última injeção e maturados in vitro com hormônio folículo estimulante (0,5 µg/mL; FSH). No experimento 3, os CCOs foram maturados in vitro na presença de três diferentes doses de MEL (10-9, 10-6 e 10-3 M) ou em FSH (controle FSH). Por fim, no experimento 4, a melhor concentração de MEL (10-9 M) eleita no experimento 3, foi utilizada sozinha ou em associação com peróxido de hidrogênio (300µM; H2O2). Os CCOs foram maturados como no experimento anterior. Para os quatro experimentos foram avaliados a taxa de maturação mediante a extrusão do primeiro corpúsculo polar (1º CP) e a expressão de genes relacionados à apoptose (Bax e Bcl2l1) e enzimas antioxidantes (Gpx1, Sod1 e Sod2) por qPCR-RT tanto para as células do cumulus (CC), quanto para os oócitos (OO). No experimento 1, o tratamento com 20 mg/kg de MEL apresentou maior taxa de maturação in vivo de 80,3%, seguido do controle (69,4%) e 10 mg/kg de melatonina (62,4%; P>0,05). Para a expressão gênica não houve efeito de nenhum tratamento (P>0,05). No experimento 2, a taxa de maturação variou de 39 a 53,2% entre os tratamentos (P>0,05). Em CC, a expressão gênica foi diminuída de Bcl2l1 e aumentada de Gpx1 tratados com 20 mg/kg de MEL (P<0,05). Já para OO, somente houve aumento da expressão de Gpx1 para ambos os tratamentos com MEL (P<0,05). No experimento 3, a taxa de maturação foi de 48,9%, 53,7%, 56% e 57,3% para 10-3, 10-6, 10-9 M de MEL e FSH, respectivamente (P>0,05). As concentrações de 10-9 e 10-6 M de MEL aumentaram a expressão dos genes Gpx1 e Sod1 em CC (P<0,05). Em OO, somente houve aumento da expressão gênica de Bax na concentração de 10-6 M de MEL (P<0,05). No último experimento, não houve diferença significativa quanto à taxa de maturação, variando de 51,8% para o tratamento com H2O2 a 60% para o controle FSH (P>0,05). Em CC, Gpx1 e Sod1 tiveram suas expressões aumentadas em todos os tratamentos (P<0,05). De maneira contrária, o gene Bcl2l1 teve sua expressão diminuída (P<0,05). Com base nestes dados, conclui-se que a MEL aplicada in vivo não foi capaz de melhorar a taxa de maturação in vivo e in vitro, porém, em condições in vitro induziu a progressão da meiose em oócitos murinos. Além disso, em condições in vitro, genes antioxidantes como Gpx1 e Sod1 foram mais expressos em CC do que em OO em resposta ao tratamento com MEL, indicando a indução de um possível efeito protetor frente à condições de cultivo in vitro. / Many factors are involved in the control of oocyte maturation and developmental competence. Melatonin (MEL) is a hormone showing varied functions including antioxidant and antiapoptotic activities, besides influencing many cell signaling pathways. There are few studies on the role of MEL in oocyte maturation and the mouse, due to its quick reproduction and lower maintencance cost, is an interesting model widely used for in vitro and particularly in vivo studies. The aim of this work was to study the effects of MEL on in vivo and in vitro maturation and its cytoprotective action (antioxidant/antiapoptotic) in murine cumulus-oocyte complexes (CCOs). In experiment one, mice received MEL injections at concentrations of 0 (control), 10 and 20 mg/kg/i.p./day for 4 days. CCOs were in vivo matured and recovered 17 hours after the last injection. In experiment 2, the animals received MEL in the same dosages of the previous experiment, but for 3 days. CCOs were collected 24 hours after the last injection and in vitro matured with follicle stimulating hormone (FSH). In experiment 3, CCOs were in vitro matured with three MEL concentrations (10-9, 10-6 e 10-3 M) or FSH (FSH control). Finally, in the fourth experiment, the best concentration of MEL (10-9 M) selected in experiment 3 was used alone or in association with hydrogen peroxide (300 µM; H2O2). CCOs were matured as in the previous experiment. For all four experiments maturation rates were evaluated by extrusion of the first polar body and the expression of genes related to apoptosis (Bax and Bcl2l1) and antioxidant enzymes (Gpx1, Sod1 and Sod2) by qPCR-RT both cumulus cells (CC), and for the oocytes (OO) were assessed as well. In experiment 1, treatment with 20 mg/kg MEL showed a higher rate of in vivo maturation of 80.3%, followed by the control (69.4%) and 10 mg/kg MEL (62.4%; P>0.05). No effect for gene expression treatments (P>0.05) was observed. In experiment 2, maturation rate ranged from 39 to 53.2% between treatments (P>0.05). In CC, the gene expression was reduced for Bcl2l1 and enhanced for Gpx1 in animals treated with 20 mg/kg MEL (P<0.05). For OO, only Gpx1 expression was increased for both MEL treatments (P<0.05). In experiment 3, the maturation rates were 48.9, 53.7, 56 e 57.3% for MEL 10-3, 10-6, 10-9 M and FSH, respectively (P>0.05). MEL concentrations of 10-6 and 10-9 M increased expression of Gpx1 and Sod1 genes in CC (P<0.05). For OO, only Bax increased the gene expression in 10-6 M MEL concentration (P<0.05). In the last experiment, there was no significant difference in maturation rate, ranging from 51.8 for H2O2 to 60% for FSH control (P>0.05). Gpx1 and Sod1 genes had their expression increased in all the treatments in CC (P<0.05). For Bcl2l1 gene, the expression was decreased in CC as well (P<0.05). Based on these data, we conclude that MEL treatment in vivo was unable to promote maturation rate in vivo and in vitro, but under in vitro conditions it induced meiosis progression in murine oocytes. In addition, Gpx1 and Sod1 antioxidant genes were more expressed in CC than OO in response to MEL treatments in vitro indicating induction of a possible protective effect against in vitro culture conditions.

A lagarta L. obliqua tem se destacado por apresentar em sua hemolinfa proteínas com atividade biológica demonstrada em cultivos celulares. A literatura disponível não apresenta trabalhos sobre a expressão da proteína antiapoptótica de L. obliqua, então este estudo objetiva a clonagem e expressão da proteína antiapoptótica presente na hemolinfa de L. obliqua, em sistema bacteriano Escherichia coli. O RNAm extraído do tegumento de L. obliqua deu origem a um cDNA obtido por RT-PCR, o qual foi clonado em vetor pCR II-TOPO para posterior transformação de bactérias E. coli JMQC. Na expressão heteróloga, o fragmento foi subclonado em vetor pET28a e transformadas bactérias E. coli BLQC. A indução de expressão foi realizada com IPTG 1 mM. A APLOrEC purificada por cromatografia foi identificada por Western Blot. A atividade biológica da APLOrE foi analisada em células VERO e L929 após indução de morte e verificou-se que esta protegeu os cultivos induzidos com 4mM de H2O2 portanto, eficaz na manutenção estrutural do citoesqueleto destas células. / The caterpillar L. obliqua has become known for performing in their hemolymph proteins with biological activity demonstrated in cell cultures. The available literature does not provide studies on the expression of antiapoptotic protein L. oblique, so this study aims cloning and expression of anti-apoptotic protein present in the hemolymph of L. oblique, bacterial system in Escherichia coli. The extracted mRNA L. obliqua husk gave a cDNA obtained by RT-PCR, which was cloned into pCR II-TOPO vector for subsequent transformation of E. coli bacteria JMQC. The heterologous expression, the fragment was subcloned into pET28a vector and transformed E. coli bacteria BLQC. The induction of expression was performed with 1 mM IPTG. The APLOrEC purified by chromatography was identified by Western blot. The biological activity was examined in APLOrE VERO and L929 cells after death induction, and it was found that this protected crops H2O2 induced with 4mM therefore effective in the structural maintenance of the cytoskeleton of such cells.

Η νόσος του Parkinson χαρακτηρίζεται από τη βαθμιαία, εκλεκτική νευροεκφύλιση των ντοπαμινεργικών νευρώνων της μελαινοραβδωτής οδού. Η μειωμένη δραστηριοποίηση των ντοπαμινεργικών υποδοχέων που προκαλείται από την ανεπάρκεια ντοπαμίνης τροποποιεί τη λειτουργία των βασικών γαγγλίων και αναστέλλει τα κινητικά συστήματα. Ιδανικό πειραματικό μοντέλο αποτελεί το μοντέλο weaver, το οποίο εμφανίζει το ίδιο μοτίβο νευροεκφύλισης με τους παρκινσονικούς ασθενείς καθώς και περισσότερη από 70% μείωση της ντοπαμίνης στο ραβδωτό σώμα. Το γεγονός πως δεν υπάρχει σήμερα αποτελεσματική θεραπεία που να σταματά ή να αναστρέφει την εξέλιξη της νόσου, δημιουργεί την ανάγκη ανακάλυψης ενός φαρμακευτικού σχήματος το οποίο θα έχει νευροπροστατευτική δράση και θα περιορίζει τις παρενέργειες. Προηγούμενα αποτελέσματα της ομάδας μας δείχνουν σημαντική επιβίωση των ντοπαμινεργικών κυττάρων στο μοντέλο weaver μετά από χρόνια χορήγηση του ενδογενούς νευροστεροειδούς DHEAS, του χημικού αναλόγου του ΒΝΝ-50 (το οποίο δε μεταβολίζεται σε οιστρογόνα) και του φαρμακευτικού συνδυασμού του ΒΝΝ-50 με τη Ν-ακετυλοκυστεΐνη (NAC), με το τελευταίο να επαναφέρει πλήρως τον αριθμό των κυττάρων στη μέλαινα ουσία. Στην παρούσα εργασία θελήσαμε να διερευνήσουμε τους μηχανισμούς μέσω των οποίων επιτυγχάνεται η νευροπροστασία που προκαλεί η συγχορήγηση του συνδυασμού BNN-50/ΝAC. Για το σκοπό αυτό, αξιολογήσαμε την αντιαποπτωτική, καθώς και την αντιοξειδωτική δράση του σχήματος BNN-50/NAC. Οι δύο δείκτες επιλέχθηκαν λαμβάνοντας υπόψιν τον κεντρικό ρόλο του αποπτωτικού θανάτου στη διαδικασία της νευροεκφύλισης, καθώς και το ρόλο του οξειδωτικού στρες στην παθογένεια της νόσου. Τα αποτελέσματα μας υποδεικνύουν πλειοτροπική δράση του φαρμακευτικού συνδυασμού BNN-50/NAC, η οποία εκφράζεται μέσω της ισχυρής αντιαποπτωτικής και αντιοξειδωτικής του δράσης. / Parkinson 's disease is characterized by the progressive, selective neurodegeneration of the dopaminergic neurons of the nigrostriatal pathway. The decreased activation of dopamine receptors caused by insufficient dopamine levels, modifies the function of the basal ganglia circuit and inhibits the mobility systems. The weaver model consists an ideal model for neuroprotection studies, which exhibits the same pattern of neurodegeneration as the parkinsonian patients and more than 70% decrease of dopamine in the striatum. The fact that there is currently no effective treatment to attenuate or reverse the disease progression, creates the need for discovery of a drug combination which will exhibit neuroprotective effect and reduce the side effects. Previous results of our group, have shown a significant survival of dopaminergic neurons in weaver mice after chronic administration of endogenous neurosteroid DHEA-S, the chemical analog BNN-50 (which is not metabolized to estrogens) and the combination of the BNN-50 with N-acetylcysteine (NAC,with the latter combination completely rescuing the number of dopaminergic cells of the substantia nigra. The aim of this study was to investigate the mechanisms of neuroprotection induced by coadministration of combination BNN-50/NAC. For this purpose, we evaluated the possible antiapoptotic and antioxidant action of the BNN-50/NAC combination. Our results suggest a pleiotropic effect of the BNN-50/NAC drug combination, that is expressed through strong antiapoptotic and antioxidant activity.

A hiporreatividade das células T observada na resposta imune a antígenos de P. brasiliensis de pacientes com paracoccidioidomicose ativa deve contribuir para o não controle da doença, levando à disseminação do fungo. É, na maioria das vezes, reversível com tratamento antifúngico. Os mecanismos que levam a esta hiporreatividade não são bem conhecidos. No entanto, foram demonstrados em resultados prévios em nosso laboratório que células mononucleares de pacientes frente a gp43 apresentam níveis elevados de apoptose. Para tentarmos explicar esse mecanismo, nossa primeira hipótese foi de avaliar se a ativação celular desses pacientes estavam sendo prejudicada por uma ativação inadequada induzida pela expressão alterada de moléculas co-estimulatórias como CD80, CD86, CD28, CD152, ICOS e PD-1. A expressão dessas moléculas foi avaliada em células T e monócitos de pacientes com doença ativa (n = 7...) e controles curados (n = 2...) de um episódio prévio de PCM, mantidas em cultura com antígeno metabólico de Candida albicans (CMA), gp43 ou sem estímulo após 4 dias em cultura. Os resultados obtidos demonstraram que a expressão do CD28 foi comparável entre doentes e controles, e que a expressão de CD152, PD-1 e ICOS, que preferencialmente exercem um papel negativo na sinalização celular, foi maior em células T de pacientes, estimuladas ou não, quando comparadas com células de indivíduos controles. Em paralelo, foram realizados experimentos com a adição dos respectivos anticorpos bloqueadores, que, no entanto, não restabeleceu a proliferação celular dos pacientes. A expressão das moléculas CD80 e CD86 na superfície dos monócitos foi similar em pacientes e controles. Já a expressão dessas moléculas na superfície de linfócitos foi maior nos pacientes tanto em células estimuladas como não estimuladas. O bloqueio com os respectivos anticorpos no dia 0 inibiu a resposta tanto com gp43 como com CMA, porém de forma diferenciada. Nos pacientes e controles a inibição da molécula CD86 diminuiu a resposta tanto para gp43 como para CMA e a inibição da molécula CD80 diminuiu a resposta proliferativa apenas para gp43, e somente no grupo controle, sugerindo que os diferentes antígenos exigem diferentes moléculas durante o processo de apresentação antigênica. A adição desses anticorpos no 4o dia da cultura não modificou a resposta linfoproliferantiva dos pacientes e controles. Nossos dados favorecem a hipótese, derivada de outros modelos de exposição crônica a antígenos exógenos, de que a exposição repetida a antígenos de P. brasiliensis por um longo período in vivo, verificada nos pacientes com paracoccidioidomicose, levam as células T a um estado de tolerância adaptativa, que dificilmente é revertida in vitro. A partir desses resultados analisamos a participação da apoptose de células T nesse provável estado de tolerância nas células dos pacientes. Observamos que a expressão da molécula anti-apoptótica Bcl-2 está diminuída nas células T de pacientes previamente estimuladas comparadas com as células dos controles, e mesmo após o reestímulo in vitro a diminuição da expressão dessa molécula persiste. Desta forma, a diminuição da expressão da molécula Bcl-2 ex vivo nas células T de pacientes sugere fortemente que essas células estão vulneráveis a apoptose. Para corroborar esta hipótese, analisamos a expressão das caspases 8 e 9 na forma ativa. Inicialmente, analisamos a expressão destas moléculas em células mononucleares de pacientes e controles mantidas em cultura por 4 dias com e sem estímulo de CMA e gp43 e observamos que as células dos controles expressam maiores níveis de ambas moléculas em relação as células dos pacientes. Esses resultados foram surpreendentes uma vez que o aumento da expressão de moléculas que estariam direcionando as células para apoptose era esperado em células de pacientes e não de controles. Para explicar este resultado sugerimos a possibilidade (hipótese já apareceu várias vezes) de que as células dos pacientes poderiam estar entrando em apoptose num estágio mais inicial, antes do quarto dia. Por isso realizamos experimentos adicionais em que analisamos a expressão dessas caspases ex vivo. Com essa análise observamos que células TCD3+ de pacientes expressam altos níveis tanto de caspase 8 como caspase 9 comparadas às células de controles. Esses resultados podem ajudar a explicar porque nos ensaios para a análise da resposta proliferativa de pacientes com acréscimo de anticorpos bloqueadores de moléculas coestimulatórias, não houve reconstituição da resposta especifica a gp43: essas células estariam pré-ativadas e pré-programadas para entrarem apoptose, e, portanto, refratárias a tratamentos in vitro, como já descrito em células em estado de tolerância adaptativa. / The T-cell hypoproliferative reactivity observed in the immune response to P. brasiliensis antigens of patients with active paracoccidioidomycosis probably contributes to the failure of the host in controlling the infection, leading to a disseminated disease. It is, however, largely reversible with treatment in most patients. The mechanisms leading to this hyporresponsiveness are not well known. We have previously demonstrated that patients\' mononuclear cells in presence of gp43 exhibit enhanced apoptotic levels. I an attempt to explain such findings, we hypothethized that these cells were inadequately activated due to altered costimulatory molecules expression, such as CD80, CD86, CD28, CD152, ICOS e PD-1. Expression of these molecules were evaluated on T-cells and monocytes of the peripheral blood of patients with active, disseminated PCM (n = 7...), and healthy individuals with a past history of treated and cured PCM (n = 2...). These cells were cultured in presence of a Candida albicans metabolic antigen (CMA), gp43, or kept without exogenous stimuli for 4 days. Our results show tgat the expression of CD28 was comparable between patients an controls\' cells, and that CD152, PD-1 e ICOS, all of which known to deliver negative costimulatory signaling and to arrest cell cycle entry, were overexpressed in patients\' T-cells. In parallel, we performed additional experiments where the respective costimulatory signalings were blocked by addition of blocking antibodies specific to each of these molecules. Whatever the blocking antibody used, there was no reversal of the hypoproliferative state of patients\' T-cells. However, while the expression of the CD80 and CD86 molecules on monocytes was similar between controls and patients, their expression on T-cells was significantly higher in patients. Adding the respective blocking antibodies at day zero of the culture, we could observe that both the gp43 and the CMA responses were inhibited, but differentially according to the antibody employed. In both patients and controls the blocking CD86 signaling decreased the response to gp43 and CMA of patients and controls, while blocking of CD80 signaling decreased only the response to gp43, and only in the control group. These data suggest that different antigens may have different costimulatory requirements for antigen presentation. Addition of the antibodies at the ay 4 of culture did not restore the lymphoproliferative response or modified the response of the controls. Our results suggest that the hypothesis, raised from other models of prolonged foreign antigen exposure, that repetitive and persistent in vivo exposure to fungal antigens, which is described in patients with PCM, lead the T-cells to a adaptive tolerant state, which is hardly reverted in vitro. We then investigated the fate of such putatively tolerized patients\' cells, by analyzing the role that apoptosis may have in this tolerant state. We observed that expression of the antiapoptotic molecule Bcl-2 was lower in patients\' cells, even when the cells were in vitro reestimulated with CMA and gp43, suggesting that the cells are more susceptible to undergo apoptosis. When then analyzed the expression of the active form of the caspase 8 and 9 molecules. We first analyzed their expression on cells kept in cultures for 4 days with or without stimuli. Unexpectedly, we observed that controls\' cells, and not patients\' cells, exhibited higher levels of expression of both molecules. To explore further these data, we tested the hypothesis that the patients\' cells were already undergoing apoptosis at an earlier than 4 days stage. Caspases expression were therefore analyzed ex vivo. In fact, we observed that TCD3+ cells exhibited markedly enhanced caspase 8 and expression as compared to controls\' cells. These findings may help to explain why we failed to redress the proliferative responses to gp43 in the experiments where blocking antibodies were added: these cells would be committed to apoptotic death, thus refractory to in vitro manipulations, as described for adaptively tolerant T-cells.