Sulforaphane reduces the alterations induced by quinolinic acid: modulation of glutathione levels.

Glutamate-induced excitotoxicity involves a state of acute oxidative stress, which is a crucial event during neuronal degeneration and is part of the physiopathology of neurodegenerative diseases. In this work, we evaluated the ability of sulforaphane (SULF), a natural dietary isothiocyanate, to induce the activation of transcription factor Nrf2 (a master regulator of redox state in the cell) in a model of striatal degeneration in rats infused with quinolinic acid (QUIN). Male Wistar rats received SULF (5mg/kg, i.p.) 24h and 5min before the intrastriatal infusion of QUIN. SULF increased the reduced glutathione (GSH) levels 4h after QUIN infusion, which was associated with its ability to increase the activity of glutathione reductase (GR), an antioxidant enzyme capable to regenerate GSH levels at 24h. Moreover, SULF treatment increased glutathione peroxidase (GPx) activity, while no changes were observed in γ-glutamyl cysteine ligase (GCL) activity. SULF treatment also prevented QUIN-induced oxidative stress (measured by oxidized proteins levels), the histological damage and the circling behavior. These results suggest that the protective effect of SULF could be related to its ability to preserve GSH levels and increase GPx and GR activities.

La frecuencia cardiaca en fetos con circular de cordón / Heart rate in fetuses with coiling of funis

Objetivo: Se determinaron los valores de la frecuencia cardiaca y la incidencia de dips tipos i y ii en los fetos con circular de cordón. Diseño del estudio La muestra la integraron 40 pacientes, se dividió en 2 grupos: Grupo 1: 20 pacientes embarazadas con diagnóstico de circular de cordón o grupo problema; Grupo 2: 20 pacientes con embarazo normal o grupo testigo. Se practicaron registros de frecuencia cardiaca fetal y contractilidad uterina durante 2 h. Para el análisis estadístico se utilizaron el programa SPSS® y las pruebas t de Student y Z. Resultados En el grupo problema la frecuencia cardiaca fetal (FCF) fue de 138 latidos por minuto (lat/min) y en el testigo de 135 lat/min. En el primer grupo, esta se incrementó 3 lat. Se calculó si la diferencia entre medias era o no significativa. Se utilizaron las pruebas de Z-score cuyo valor fue de 8,65 y p < 0,01: esta fue significativa. En los 2 grupos se calcularon los valores de la amplitud de las aceleraciones. Estas fueron semejantes: 24 lat. La diferencia entre medias no fue significativa. El análisis comparativo entre el peso y la talla de los recién nacidos en el grupo problema fue de 3.100 g y la talla de 50,72 cm. En el testigo fue de 2.960 g y 49,77 cm respectivamente. La diferencia entre medias no fue significativa. A los recién nacidos se les valoró con la prueba de Apgar. En el grupo problema, durante el primer minuto la calificación tuvo un rango de 7-9 y en el quinto de 8-9. En el grupo testigo las calificaciones fueron semejantes. Se cuantificaron los dips tipos i y ii . De los primeros dips se registraron 3 y de los segundos 2, uno con gran amplitud y duración. No se registraron dips tipo iii . En ninguno de los partos hubo presencia de meconio. Conclusiones En la circular de cordón floja: no hubo cambios significativos en la FCF. Circular de cordón apretada produjo: dips tipo ii de gran amplitud (AU)

Objective: To determine heart rate and the frequency of type i and ii dips in fetuses with coiling of funis. Study design: There were 40 patients in the sample, divided in two groups: group 1: consisted of 20 pregnant women with a diagnosis of coiling of funis; group ii consisted of 20 patients with a normal pregnancy. Fetal heart rate (HR) and uterine contractility were recorded for 2 hours. For the statistical analysis, the SPSS® package, Z-score and Student’s t-test were used. Results: Fetal HR was 138 beats/min in group 1 and 135 beats/min in group ii. The difference between medians (Z-score) was 8.65, which was significant (P<.01).Amplitude and accelerations were calculated in both groups, with similar results (24 beats).The difference in means was not significant. The mean weight and height were compared in the two groups. Mean weight was 3,100 g in group 1 and 2,960 in group 1, while mean height was 50.72 cm in group i and 49.77 in group 2.The difference in means was not significant. Apgar tests were performed in both groups. In group 1, Apgar scores ranged from 7-9 at1 minute and from 8-9 at 5 minutes. Values were similar in group 2.Type i dips gave a reading of 3, and type ii dips a reading of 2 (one with marked height and duration). No type iii dips were observed. No meconium was found in any of the deliveries. Conclusions: In pregnancies with loosely coiled funises, there were no significant changes in fetal HR. In pregnancies with tightly coiled funises, type ii dips with wide amplitude and marked duration were found (AU)

Anestesia intracervical para la realización del legrado uterino instrumental / Intracervical anesthetic infiltration for use with instrumental uterine curettage

OBJETIVO: En esta investigación se evaluó la infiltración anestésica intracervical en pacientes en situación de aborto para realizar el legrado uterino instrumental. Pacientes y métodos Se estudió una muestra de 20 pacientes en situación de aborto. El estudio fue abierto, prospectivo y exploratorio. La edad de las pacientes tuvo un rango de 17 a 49 años de edad, con una media y desviación estándar de 26,95 ± 9,2058. La edad de la gestación tuvo un rango de 5 a 14 semanas con una media y desviación estándar de 8,75 ± 2,4622. Para el análisis estadístico se usó el programa SPSS. Para la anestesia intracervical se utilizó lidocaína al 1%, 10 ml; 5 ml en cada una de las infiltraciones, la primera a las III y la segunda a las IX de las manecillas del reloj. RESULTADOS: La duración de la anestesia tuvo un rango de 30 a 70 min, con una media y desviación estándar de 48,25 ± 13,8992. CONCLUSIÓN: La duración del tiempo quirúrgico desde la infiltración anestésica y el legrado uterino tuvieron un rango de 7 a 14min, con una media y desviación estándar de 10,9 ± 2,1886. El sangrado tuvo un rango de 50 a 150ml, con una media y desviación estándar de 100 ± 44,7213. Todos los estudios fueron longitudinales

Objetive: We performed an open, prospective, exploratory and longitudinal study to evaluate the use of intracervical anesthetic infiltration with instrumental uterine curettage in 20 women undergoing pregnancy termination. PATIENTS AND METHODS: The patients' age ranged from 17 to 49 years (mean and SD:26.95±9.2058). The length of gestation ranged from 5 to 14 weeks (mean and SD:8.75±2.4622). The SPSS program was used for the statistical analysis. RESULTS: For intracervical anesthesia, 10 ml lidocaine at 1% was used; 5ml was applied at infiltration points III and IX clockwise. Anesthesia lasted 30 to 70 minutes (mean and SD: 48.25 ± 13.8992). CONCLUSIONS: Operating time (infiltration and curettage) ranged from 7 to 14 minutes (mean and SD: 10.9 ± 2.1886). Blood loss ranged from 50 to 150ml (mean and SD: 100 ± 44.7213). All studies were longitudinal

Characterization of the first Batrachochytrium dendrobatidis isolate from the Colombian Andes, an amphibian biodiversity hotspot.

The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd), constitutes a significant threat to more than 790 amphibian species occurring in Colombia. To date there is no molecular or morphological description of strains infecting Colombian populations. Here we report the genetic and morphological characterization of the first Colombian isolate of Bd (strain EV001). Our goals were threefold: (1) to characterize the morphology of EV001 using light and scanning electron microscopy, (2) to genotype this strain by direct sequencing of 17 polymorphic nuclear markers developed previously, and (3) to compare our findings with published reports on strains from other areas of the globe. We found that EV001 is morphologically consistent with previously described strains. Multi-locus genotyping suggested that EV001 is grouped genetically with Panamanian strains and is most similar to strain JEL203 isolated from a captive individual. This finding fills an important gap in our knowledge of Neotropical strains of Bd and provides a baseline for further evolutionary and functional analyses.

Heme oxygenase-1 (HO-1) upregulation delays morphological and oxidative damage induced in an excitotoxic/pro-oxidant model in the rat striatum.

Quinolinic acid (QA)-induced overactivation of N-methyl-d-aspartate receptors yields excitotoxicity, oxidative stress and mitochondrial dysfunction, which altogether contribute to trigger a wide variety of toxic pathways with biochemical, behavioral and neuropathological alterations similar to those observed in Huntington's disease. Noteworthy, in the brains of these patients, increased expression of heme oxygenase-1 (HO-1) levels can be found. It has been proposed that this enzyme can exert a dual role, as it can be either protective or deleterious to the CNS. While some evidence indicates that its overexpression affords cellular anti-oxidant protection due to decreased concentrations of its pro-oxidative substrate heme group, and increased bilirubin levels, other reports established that high HO-1 expression and activity may result in a pro-oxidizing atmosphere due to a release of Fe(2+). In this work, we examined the temporal evolution of oxidative damage to proteins, HO-1 expression, immunoreactivity, total activity, and cell death after 1, 3, 5 and 7 days of an intrastriatal QA infusion (240 nmol/µl). QA was found to induce cellular degeneration, increasing carbonylated proteins and generating a transitory response in HO-1 mRNA, protein content, and immunoreactivity and activity in nerve cells. In order to study the role of HO-1 in the QA-induced cellular death, the tin protoporphyrin IX (SnPP), a well-known HO inhibitor, was administered to rats (30 µmol/kg, i.p.). The administration of SnPP to animals treated with QA inhibited the HO activation, and exacerbated the striatal cell damage induced by QA. Our findings reveal a potential modulatory role of HO-1 in the toxic paradigm evoked by QA in rats. This evidence provides a valuable tool for further approaches on HO-1 regulation in neurotoxic paradigms.

First Report of Phytophthora infestans Causing Late Blight on Solanum viarum in Colombia.

Solanum viarum Dunal (tropical soda apple) belongs to the section Acanthophora in the genus Solanum, which includes nearly 20 neotropical species of herbs and small shrubs (2). The species in this section are sometimes called the 'spiny Solanums' (2) and are adapted mainly to highly disturbed habitats and open secondary forests. The center of diversity is eastern Brazil (3). Since the early 1990s, S. viarum has been a problematic weed in Florida where it was listed as a noxious weed in 1993, followed in 1994 by its addition to the Federal Noxious Weed List of the USDA. On 17 April 2010, 12 plants of S. viarum located close to a S. betaceum crop (tree tomato) in the province of Caldas (Department of Antioquia, central northwestern Colombia) were found with symptoms similar to late blight caused by Phytophthora infestans on S. tuberosum (potato). Fifteen leaves from 12 plants with blackish, water-soaked lesions showing a white sporulation on the abaxial side were collected and processed within 3 days. The leaves were placed in a humid chamber and incubated in darkness at room temperature (18°C mean temperature) until sporulation was observed. Microscopic characteristics were consistent with Phytophthora spp. Only one axenic culture was obtained by successive subcultures in rye B agar plates. After an incubation period of 8 days, plates were washed with distilled water and ovoid, semipapillate caduceus sporangia ranging from 38 to 41 µm long (average 39; N = 86) and 23 to 29 µm wide (average 26; N = 86) were observed. To fulfill Koch's postulates and test the isolate for the ability to infect potato as well as Solanum spp. associated with potato crops in Colombia, triplicate pathogenicity tests were carried out on three detached leaves of S. viarum, S. tuberosum, and S. americanum (American nightshade). A 1 × 104 sporangia/ml suspension of the Phytophthora isolate, estimated using a haemocytometer, was obtained from 8-day-old cultures grown on rye B agar. The suspension was incubated at 4°C for 2 h to induce zoospore release. The leaves were then inoculated by spraying them until runoff. After an incubation period of 5 days at 18°C in a humidity chamber, mycelia, sporangia, and brownish lesions, similar to those described above, were observed in the leaves of all three hosts, indicating pathogenicity. DNA extraction was performed from the P. infestans isolate (4). Four nuclear loci, ITS, ß-tubulin, Ras, and Avr3a, as well as one mitochondrial gene, cytochrome c oxidase 1 (Cox1), were amplified and sequenced. Sequences were compared with GenBank databases using Blastn. In all cases, the best hits corresponded to P. infestans (GenBank Accession No. HQ639930 for Avr3A, HQ639931 for ß-tubulin, HQ639932 for Cox1, HQ639933 for iRas, HQ639934 for Ras, and JF419363 for ITS). Reports of P. infestans causing typical late blight symptoms on wild solanaceous plants are becoming more frequent and have been made from other countries such as Peru (1). To our knowledge, this is the first time that P. infestans has been observed and isolated from S. viarum in Colombia, introducing the possibility of this wild solanaceous weed as another late blight host. References: (1) G. Garry et al. Eur. J. Plant Pathol. 113:71, 2005. (2) R. Levin et al. Am. J. Bot. 92:603, 2005. (3) M. Nee. A Revision of Solanum Section Acanthophora. Ph.D. diss. University of Wisconsin, Madison, 1979. (4) A. M. Vargas et al. Phytopathology 99:82, 2009.

La frecuencia cardíaca fetal en pacientes con diagnóstico de preeclampsia leve y grave / Fetal heart rate in patients with mild and severe preeclampsia

El objetivo de la investigación fue calcular el valor de los índices de la frecuencia cardíaca fetal (FCF) basal, ascensos transitorios y los dips tipos I y II, entre las semanas de gestación 25 y 35, en pacientes con diagnóstico de preeclampsia leve y grave, y comparar los valores obtenidos con un grupo testigo y determinar si la diferencia entre medias de la FCF basal y la amplitud de las aceleraciones era o no significativa. El diseño fue abierto, prospectivo, comparativo y exploratorio. La muestra la integraron 40 pacientes dividida en 3 grupos: 1) preeclampsia leve; 2) preeclampsia grave, y 3) un grupo testigo de 20 pacientes previamente estudiado. En el grupo 1 (n = 10), la edad de las pacientes tuvo una media de 27,4 años (desviación estándar [DE] de 6,8); la edad de la gestación tuvo una media de 32,5 semanas (DE de 4,92). En el grupo 2 (n = 10), la edad de las pacientes tuvo una media de 28 años (DE de 6,2); la edad de la gestación tuvo una media de 31,31 semanas (DE de 3,70). En el grupo testigo (n = 20), la edad de las pacientes tuvo una media de 27,45 años (DE de 5,69); la edad de la gestación tuvo una media de 33,25 semanas (DE de 3,1). En las primeras 24h del ingreso de la paciente se tomó un cardiotocograma y se repitió durante las 24h de la iniciación del trabajo de parto o antes de la intervención quirúrgica (cesárea). Se equipararon los valores entre grupos de la FCF basal normal y con diagnóstico de preeclampsia leve y grave durante el primer estudio, los valores entre el 1º y el 2º grupo fueron de 135,5 y 138,69 y los valores entre el primero y el tercer grupo fueron de 135,5 y 137,66; la diferencia entre medias fue de 3 latidos con el primer grupo y de 2 latidos con el segundo grupo; los valores de ⩾P indicaron que ésta fue significativa. En el segundo estudio los valores de la media entre el primero y el segundo estudio fueron de 135,5 y 142,63 y entre el primero y el tercero fueron de 135,5 y 135,52; la diferencia fue de 7 latidos con el primer grupo y no hubo diferencia con el segundo; el valor de ⩾P indicó que ésta fue significativa entre el primero y el segundo grupo. Se equipararon los valores entre grupos de las aceleraciones normales y con diagnóstico de preeclampsia leve y grave. 1er estudio: en el grupo testigo, el valor de la media fue de 24,81 latidos, en el grupo de preeclampsia leve fue de 23,03 latidos y en el grupo de preeclampsia grave fue de 21,80 latidos. La diferencia entre medias de los grupos 1 y 2 fue de un latido y entre los grupos 1 y 3 fue de 3 latidos; los valores de ⩾P indicaron que éstas fueron significativas. 2º estudio: en el grupo testigo, el valor de la media fue de 24,81 latidos, en el grupo de preeclampsia leve fue de 20,43 latidos y en el grupo de preeclampsia grave fue de 16,78 latidos; la diferencia entre medias fue de 4 latidos entre el primero y el segundo grupo y de 8 entre el primero y el tercero; los valores de ⩾P indicaron que éstas fueron significativas. Grupo 1: el estado físico de los recién nacidos se valoró de acuerdo con la prueba de Apgar. En el primer minuto la calificación tuvo un rango de 3 a 9, y en el quinto minuto la calificación fue de 9 para todos. Grupo 2: en el primer minuto la calificación de Apgar tuvo un rango de 5 a 9, hubo 3 recién nacidos deprimidos, y en el quinto minuto el rango fue de 7 a 9. Se equiparó el peso de los recién nacidos: en el grupo testigo la media fue de 2,950 g; en el grupo de preeclampsia leve fue de 2,842 g y en el grupo de preeclampsia grave fue de 1,770 g; el valor de < P indicó que la diferencia entre medias fue altamente significativa (AU)

The aim of this study was to calculate baseline fetal heart rate (FHR) together with temporary heartbeat rises and falls (types I and II) occurring between weeks 25 and 35 of pregnancy in patients diagnosed with mild or severe preeclampsia. The measurements obtained were compared with those of a control group to determine whether the differences among the mean values of baseline FHR and the amplitude of accelerations were significant. The study design was open, prospective, comparative and exploratory. The sample consisted of 40 patients divided into three groups: mild preeclampsia (group I) and severe preeclampsia (group II). There was also a control group (group III) of 20 patients. In group I (n=10) the mean age (±SD) of the patients was 27.4±6.8. The mean (±SD) length of pregnancy was 32.5±4.92 weeks. In group 2 (n=10) the mean age of the patients was 28±6.2. The mean length of pregnancy was 31.31±3.70 weeks. In the control group (n=20), the mean age of the patients was 27.45±5.69. The mean length of pregnancy was 33.25±3.11 weeks. A cardiotocogram was performed during the first 24h after admission and was repeated during the 24h after the beginning of labor or before surgical intervention (cesarean section). The measurements taken in the first study were compared among the three groups. Group I registered 135.5 heart beats, group II 138.69 and group III 137.66. The difference between the mean values of groups I and II was 3 heart beats and that between groups I and III was 2 heartbeats, with P-values indicating statistical significance. In the second study, the mean values were 135.5 in group I, 142.63 in group II and 135.52 in group III. The difference between groups I and II was 7 beats/ min, which was statistically significant. There was no difference between groups I and III. The values for normal accelerations were compared with the diagnoses of mild or severe preeclampsia. In the first study, the mean value was 24.81 beats in group III (controls), 23.03 in group I (mild preeclampsia) and 21.80 in group III (severe preeclampsia). The difference in mean values was 1 beat between groups I and II and 3 beats between groups I and III and these differences were statistically significant. In the second study, the mean heart beat was 24.81 in group III, 20.43 in group I and 16.78 in group II. The differences between means were 4 heart beats between groups I and II, and 8 beats between groups I and III, with these differences being significant. The physical status of the newborns was evaluated by using the Apgar test. In group I, at 1min, scores ranged from 3 to 9. At 5min, the score was 9 for all neonates. In group II, at 1min, scores ranged from 5 to 9 and three children (at the bottom of the scale) were «depressed». At 5min, the range was between 7 and 9. The weights of the neonates were compared. The mean value was 2.960 in the control group, 2.842 in group I and 1.770 in group II. The differences between these means were highly significant (AU)

Aged garlic extract delays the appearance of infarct area in a cerebral ischemia model, an effect likely conditioned by the cellular antioxidant systems.

Experimental evidence has shown that some garlic-derived products have a protective effect against ischemic brain injury. The present study was designed to investigate the effect of aged garlic extract (AGE), establish the therapeutic window, and determine its protective mechanism in a cerebral ischemia model. Animals were subjected to middle cerebral artery occlusion (MCAO) for 2h and treated with 1.2ml/kg body wt.(i.p.) of AGE 30min before, at the beginning of (0R), or 1h after reperfusion. The 0R treatment significantly reduced the size of the infarct area after 2h of reperfusion. Repeated doses subsequent to the 0R treatment (at 1, 2, or 3h after reperfusion) had no effect on the temporal window of protection. The protective 0R treatment with AGE prevented the increase in nitrotyrosine and the decrease in total superoxide dismutase, glutathione peroxidase, and extracellular superoxide dismutase activities induced by MCAO. These data indicate that AGE delays the effects of ischemia/reperfusion-induced neuronal injury. However, this treatment itself was not associated with a noticeable improvement in the neurological outcome, or with an effect on the inflammatory response. We conclude that the neuroprotective effect of AGE in the 0R treatment might be associated with control of the free-radical burst induced by reperfusion, preservation of antioxidant enzyme activity, and the delay of other pathophysiological processes.

Physiological and molecular characterization of atypical isolates of Malassezia furfur.

The species constituting the genus Malassezia are considered to be emergent opportunistic yeasts of great importance. Characterized as lipophilic yeasts, they are found in normal human skin flora and sometimes are associated with different dermatological pathologies. We have isolated seven Malassezia species strains that have a different Tween assimilation pattern from the one typically used to differentiate M. furfur, M. sympodialis, and M. slooffiae from other Malassezia species. In order to characterize these isolates of Malassezia spp., we studied their physiological features and conducted morphological and molecular characterization by PCR-restriction fragment length polymorphism and sequencing of the 26S and 5.8S ribosomal DNA-internal transcribed spacer 2 regions in three strains from healthy individuals, four clinical strains, and eight reference strains. The sequence analysis of the ribosomal region was based on the Blastn algorithm and revealed that the sequences of our isolates were homologous to M. furfur sequences. To support these findings, we carried out phylogenetic analyses to establish the relationship of the isolates to M. furfur and other reported species. All of our results confirm that all seven strains are M. furfur; the atypical assimilation of Tween 80 was found to be a new physiological pattern characteristic of some strains isolated in Colombia.

Nutrient signaling through TOR kinases controls gene expression and cellular differentiation in fungi.

The TOR kinases were first identified in Saccharomyces cerevisiae as the targets of the immunosuppressive drug rapamycin. Subsequent studies employing rapamycin as a tool in yeast have given us insight into the structure and function of the TOR kinases, as well as the biological role of the TOR signaling program in transmitting nutrient signals to promote cell growth. One of the major advances from this area has been in defining an unexpected role for TOR signaling in the regulation of transcription. The identification of target genes subject to regulation by TOR has provided a platform for the dissection of the signaling events downstream of the TOR kinases. Studies aimed at understanding TOR-regulated transcription have begun to shed light on how TOR signaling cooperates with other signaling programs. In addition, the TOR pathway regulates the developmental program of pseudohyphal differentiation in concert with highly conserved MAP kinase and PKA signaling programs. Remarkably, rapamycin also blocks filamentation in a number of important human and plant pathogens and the mechanism of rapamycin action is conserved in Candida albicans and Cryptococcus neoformans. The antimicrobial properties of less immunosuppressive analogs of rapamycin hold promise for the development of an effective antifungal therapy.

The TOR signal transduction cascade controls cellular differentiation in response to nutrients.

Rapamycin binds and inhibits the Tor protein kinases, which function in a nutrient-sensing signal transduction pathway that has been conserved from the yeast Saccharomyces cerevisiae to humans. In yeast cells, the Tor pathway has been implicated in regulating cellular responses to nutrients, including proliferation, translation, transcription, autophagy, and ribosome biogenesis. We report here that rapamycin inhibits pseudohyphal filamentous differentiation of S. cerevisiae in response to nitrogen limitation. Overexpression of Tap42, a protein phosphatase regulatory subunit, restored pseudohyphal growth in cells exposed to rapamycin. The tap42-11 mutation compromised pseudohyphal differentiation and rendered it resistant to rapamycin. Cells lacking the Tap42-regulated protein phosphatase Sit4 exhibited a pseudohyphal growth defect and were markedly hypersensitive to rapamycin. Mutations in other Tap42-regulated phosphatases had no effect on pseudohyphal differentiation. Our findings support a model in which pseudohyphal differentiation is controlled by a nutrient-sensing pathway involving the Tor protein kinases and the Tap42-Sit4 protein phosphatase. Activation of the MAP kinase or cAMP pathways, or mutation of the Sok2 repressor, restored filamentation in rapamycin treated cells, supporting models in which the Tor pathway acts in parallel with these known pathways. Filamentous differentiation of diverse fungi was also blocked by rapamycin, demonstrating that the Tor signaling cascade plays a conserved role in regulating filamentous differentiation in response to nutrients.

Rapamycin and less immunosuppressive analogs are toxic to Candida albicans and Cryptococcus neoformans via FKBP12-dependent inhibition of TOR.

Candida albicans and Cryptococcus neoformans cause both superficial and disseminated infections in humans. Current antifungal therapies for deep-seated infections are limited to amphotericin B, flucytosine, and azoles. A limitation is that commonly used azoles are fungistatic in vitro and in vivo. Our studies address the mechanisms of antifungal activity of the immunosuppressive drug rapamycin (sirolimus) and its analogs with decreased immunosuppressive activity. C. albicans rbp1/rbp1 mutant strains lacking a homolog of the FK506-rapamycin target protein FKBP12 were found to be viable and resistant to rapamycin and its analogs. Rapamycin and analogs promoted FKBP12 binding to the wild-type Tor1 kinase but not to a rapamycin-resistant Tor1 mutant kinase (S1972R). FKBP12 and TOR mutations conferred resistance to rapamycin and its analogs in C. albicans, C. neoformans, and Saccharomyces cerevisiae. Our findings demonstrate the antifungal activity of rapamycin and rapamycin analogs is mediated via conserved complexes with FKBP12 and Tor kinase homologs in divergent yeasts. Taken together with our observations that rapamycin and its analogs are fungicidal and that spontaneous drug resistance occurs at a low rate, these mechanistic findings support continued investigation of rapamycin analogs as novel antifungal agents.

Two cyclophilin A homologs with shared and distinct functions important for growth and virulence of Cryptococcus neoformans.

Cyclophilin A is the target of the immunosuppressant cyclosporin A (CsA) and is encoded by a single unique gene conserved from yeast to humans. In the pathogenic fungus Cryptococcus neoformans, two homologous linked genes, CPA1 and CPA2, were found to encode two conserved cyclophilin A proteins. In contrast to Saccharomyces cerevisiae, in which cyclophilin A mutations confer CsA resistance but few other phenotypes, cyclophilin A mutations conferred dramatic phenotypes in C. neoformans. The Cpa1 and Cpa2 cyclophilin A proteins play a shared role in cell growth, mating, virulence and CsA toxicity. The Cpa1 and Cpa2 proteins also have divergent functions. cpa1 mutants are inviable at 39 degrees C and attenuated for virulence, whereas cpa2 mutants are viable at 39 degrees C and fully virulent. cpa1 cpa2 double mutants exhibited synthetic defects in growth and virulence. Cyclophilin A active site mutants restored growth of cpa1 cpa2 mutants at ambient but not at higher temperatures, suggesting that the prolyl isomerase activity of cyclophilin A has an in vivo function.

Calcineurin regulatory subunit is essential for virulence and mediates interactions with FKBP12-FK506 in Cryptococcus neoformans.

Calcineurin is a Ca2+-calmodulin-regulated protein phosphatase that is the target of the immunosuppressive drugs cyclosporin A and FK506. Calcineurin is a heterodimer composed of a catalytic A and a regulatory B subunit. In previous studies, the calcineurin A homologue was identified and shown to be required for growth at 37 degrees C and hence for virulence of the pathogenic fungus Cryptococcus neoformans. Here, we identify the gene encoding the calcineurin B regulatory subunit and demonstrate that calcineurin B is also required for growth at elevated temperature and virulence. We show that the FKR1-1 mutation, which confers dominant FK506 resistance, results from a 6 bp duplication generating a two-amino-acid insertion in the latch region of calcineurin B. This mutation was found to reduce FKBP12-FK506 binding to calcineurin both in vivo and in vitro. Molecular modelling based on the FKBP12-FK506-calcineurin crystal structure illustrates how this mutation perturbs drug interactions with the phosphatase target. In summary, our studies reveal a central role for calcineurin B in virulence and antifungal drug action in the human fungal pathogen C. neoformans.

The TOR kinases link nutrient sensing to cell growth.

Rapamycin is an immunosuppressive natural product that inhibits the proliferation of T-cells in response to nutrients and growth factors. Rapamycin binds to the peptidyl-prolyl isomerase FKBP12 and forms protein-drug complexes that inhibit signal transduction by the TOR kinases. The FKBP12 and TOR proteins are conserved from fungi to humans, and in both organisms the TOR signaling pathway plays a role in nutrient sensing. In response to nitrogen sources or amino acids, TOR regulates both transcription and translation, enabling cells to appropriately respond to growth-promoting signals. Rapamycin is having a profound impact on clinical medicine and was approved as an immunosuppressant for transplant recipients in 1999. Ongoing clinical studies address new clinical applications for rapamycin as an antiproliferative drug for chemotherapy and invasive cardiology.

The Ess1 prolyl isomerase is linked to chromatin remodeling complexes and the general transcription machinery.

The Ess1/Pin1 peptidyl-prolyl isomerase (PPIase) is thought to control mitosis by binding to cell cycle regulatory proteins and altering their activity. Here we isolate temperature-sensitive ess1 mutants and identify six multicopy suppressors that rescue their mitotic-lethal phenotype. None are cell cycle regulators. Instead, five encode proteins involved in transcription that bind DNA, modify chromatin structure or are regulatory subunits of RNA polymerase II. A sixth suppressor, cyclophilin A, is a member of a distinct family of PPIases that are targets of immuno suppressive drugs. We show that the expression of some but not all genes is decreased in ess1 mutants, and that Ess1 interacts with the C-terminal domain (CTD) of RNA polymerase II in vitro and in vivo. The results forge a strong link between PPIases and the transcription machinery and suggest a new model for how Ess1/Pin1 controls mitosis. In this model, Ess1 binds and isomerizes the CTD of RNA polymerase II, thus altering its interaction with proteins required for transcription of essential cell cycle genes.

Cyclophilin A and Ess1 interact with and regulate silencing by the Sin3-Rpd3 histone deacetylase.

Three families of prolyl isomerases have been identified: cyclophilins, FK506-binding proteins (FKBPs) and parvulins. All 12 cyclophilins and FKBPs are dispensable for growth in yeast, whereas the one parvulin homolog, Ess1, is essential. We report here that cyclophilin A becomes essential when Ess1 function is compromised. We also show that overexpression of cyclophilin A suppresses ess1 conditional and null mutations, and that cyclophilin A enzymatic activity is required for suppression. These results indicate that cyclophilin A and Ess1 function in parallel pathways and act on common targets by a mechanism that requires prolyl isomerization. Using genetic and biochemical approaches, we found that one of these targets is the Sin3-Rpd3 histone deacetylase complex, and that cyclophilin A increases and Ess1 decreases disruption of gene silencing by this complex. We show that conditions that favor acetylation over deacetylation suppress ess1 mutations. Our findings support a model in which Ess1 and cyclophilin A modulate the activity of the Sin3-Rpd3 complex, and excess histone deacetylation causes mitotic arrest in ess1 mutants.

Synergistic antifungal activities of bafilomycin A(1), fluconazole, and the pneumocandin MK-0991/caspofungin acetate (L-743,873) with calcineurin inhibitors FK506 and L-685,818 against Cryptococcus neoformans.

Cryptococcus neoformans is an opportunistic fungal pathogen that causes life-threatening infections of the central nervous system. Existing therapies include amphotericin B, fluconazole, and flucytosine, which are limited by toxic side effects and the emergence of drug resistance. We recently demonstrated that the protein phosphatase calcineurin is required for growth at 37 degrees C and virulence of C. neoformans. Because calcineurin is the target of potent inhibitors in widespread clinical use, cyclosporine and FK506 (tacrolimus), it is an attractive drug target for novel antifungal agents. Here we have explored the synergistic potential of combining the calcineurin inhibitor FK506 or its nonimmunosuppressive analog, L-685,818, with other antifungal agents and examined the molecular basis of FK506 action by using genetically engineered fungal strains that lack the FK506 target proteins FKBP12 and calcineurin. We demonstrate that FK506 exhibits marked synergistic activity with the H(+)ATPase inhibitor bafilomycin A(1) via a novel action distinct from calcineurin loss of function. FK506 also exhibits synergistic activity with the pneumocandin MK-0991/caspofungin acetate (formerly L-743,873), which targets the essential beta-1,3 glucan synthase, and in this case, FK506 action is mediated via FKBP12-dependent inhibition of calcineurin. Finally, we demonstrate that FK506 and fluconazole have synergistic activity that is independent of both FKBP12 and calcineurin and may involve the known ability of FK506 to inhibit multidrug resistance pumps, which are known to export azoles from fungal cells. In summary, our studies illustrate the potential for synergistic activity of a variety of different drug combinations and the power of molecular genetics to define the mechanisms of drug action, as well as identify a novel action of FK506 that could have profound implications for therapeutic or toxic effects in other organisms, including humans.

The G protein-coupled receptor gpr1 is a nutrient sensor that regulates pseudohyphal differentiation in Saccharomyces cerevisiae.

Pseudohyphal differentiation in the budding yeast Saccharomyces cerevisiae is induced in diploid cells in response to nitrogen starvation and abundant fermentable carbon source. Filamentous growth requires at least two signaling pathways: the pheromone responsive MAP kinase cascade and the Gpa2p-cAMP-PKA signaling pathway. Recent studies have established a physical and functional link between the Galpha protein Gpa2 and the G protein-coupled receptor homolog Gpr1. We report here that the Gpr1 receptor is required for filamentous and haploid invasive growth and regulates expression of the cell surface flocculin Flo11. Epistasis analysis supports a model in which the Gpr1 receptor regulates pseudohyphal growth via the Gpa2p-cAMP-PKA pathway and independently of both the MAP kinase cascade and the PKA related kinase Sch9. Genetic and physiological studies indicate that the Gpr1 receptor is activated by glucose and other structurally related sugars. Because expression of the GPR1 gene is known to be induced by nitrogen starvation, the Gpr1 receptor may serve as a dual sensor of abundant carbon source (sugar ligand) and nitrogen starvation. In summary, our studies reveal a novel G protein-coupled receptor senses nutrients and regulates the dimorphic transition to filamentous growth via a Galpha protein-cAMP-PKA signal transduction cascade.

Immunosuppressive and nonimmunosuppressive cyclosporine analogs are toxic to the opportunistic fungal pathogen Cryptococcus neoformans via cyclophilin-dependent inhibition of calcineurin.

Cyclosporine (CsA) is an immunosuppressive and antimicrobial drug which, in complex with cyclophilin A, inhibits the protein phosphatase calcineurin. We recently found that Cryptococcus neoformans growth is resistant to CsA at 24 degrees C but sensitive at 37 degrees C and that calcineurin is required for growth at 37 degrees C and pathogenicity. Here CsA analogs were screened for toxicity against C. neoformans in vitro. In most cases, antifungal activity was correlated with cyclophilin A binding in vitro and inhibition of the mixed-lymphocyte reaction and interleukin 2 production in cell culture. Two unusual nonimmunosuppressive CsA derivatives, (gamma-OH) MeLeu(4)-Cs (211-810) and D-Sar (alpha-SMe)(3) Val(2)-DH-Cs (209-825), which are also toxic to C. neoformans were identified. These CsA analogs inhibit C. neoformans via fungal cyclophilin A and calcineurin homologs. Our findings identify calcineurin as a novel antifungal drug target and suggest nonimmunosuppressive CsA analogs warrant investigation as antifungal agents.