Fábio F. Conte

Differentiated thyroid carcinomas may elude the immune system by B7H1 upregulation

B7H1 is consistently associated with inhibition of the immune system in many solid tumors. However, there is no report about its impact on differentiated thyroid carcinoma (DTC) presentation, aggressiveness, or evolution. Aiming to investigate the role of B7H1 in DTC and correlate this protein with other tumor-infiltrating immune cells, we studied 407 thyroid nodule tissue samples including 293 from DTC patients, all managed according to a same standard protocol. In addition, we obtained 5 normal and 114 benign thyroid lesions. Eighteen out of the 253 papillary thyroid carcinomas were paired with respective metastatic lymph node tissues. B7H1 (CD274) protein expression was assessed by immunohistochemistry and the gene expression was quantified by real-time PCR. Malignant tissues displayed a more intense B7H1 staining and higher mRNA levels than benign tissues (both P<0.0001). We observed a positive linear correlation between higher age at diagnosis and B7H1 mRNA levels (P=0.02896). Elevated levels of B7H1 protein were associated with the presence of CD4+, CD8+, CD20+, and FoxP3+ lymphocytes (all P<0.05); tumor-associated macrophages (P<0.0001); and the presence of myeloid-derived suppressor cells (P=0.03256). Stage II-IV patients presented higher B7H1 mRNA levels than stage I cases (P=0.03522). On the contrary, a decreased expression of B7H1 protein was observed in lymph node metastasis (P=0.0152). In conclusion, our data demonstrate that B7H1 expression is associated with features of aggressiveness, suggesting that this is an immune evasion mechanism of DTC cells.

The putative telomerase reverse transcriptase component of Leishmania amazonensis: gene cloning and characterization

The Leishmania amazonensis telomerase gene was cloned by a polymerase chain reaction-based strategy using primers designed from a Leishmania major sequence that shared similarities with conserved telomerase motifs. The genes from three other species were cloned for comparative purposes. A ClustalW multiple-sequence alignment demonstrated that the Leishmania telomerases show greater homology with each other than with the proteins of other kinetoplastids and eukaryotes. Characterization experiments indicated that the putative Leishmania telomerase gene was probably in single copy and located in the largest chromosomes. A single messenger ribonucleic acid transcript was found in promastigotes. Phylogenetic analysis suggested that Leishmania telomerase might represent a liaison between the oldest and the newest branches of telomerases.

Expression Profile of Lgi1 Gene in Mouse Brain During Development

Mutations in LGI1 were described in patients with autosomal dominant partial epilepsy with auditory features (ADPEAF), and recent clinical findings have implicated LGI1 in human brain development. However, the precise role of LGI1 in epileptogenesis remains largely unknown. The objective of this study was to determine the expression pattern of Lgi1 in mice brain during development and in adult animals. Real-time polymerase chain reaction (PCR) quantification and Western blot experiments showed a relative low expression during intrauterine stages, increasing until adulthood. In addition, we did not find significant differences between left and right hemispheres. The hippocampus presented higher levels of Lgi1 expression when compared to the neocortex and the cerebellum of adult animals; however, these results did not reach statistical significance. This study was the first to determine a specific profile of Lgi1 gene expression during central nervous system development, which suggests a possible inhibitory function in latter stages of development. In addition, we did not find differences in hemispheric expression that could explain the predominance of left-sided abnormalities in patients with ADPEAF.

Characterization of the C-terminal half of human juvenile myoclonic epilepsy protein EFHC1: Dimer formation blocks Ca2+ and Mg2+ binding to its functional EF-hand

Human EFHC1 is a member of the EF-hand superfamily of Ca(2+)-binding proteins with three DM10 domains of unclear function. Point mutations in the EFHC1 gene are related to juvenile myoclonic epilepsy, a fairly common idiopathic generalized epilepsy. Here, we report the first structural and thermodynamic analyses of the EFHC1C-terminus (residues 403-640; named EFHC1C), comprising the last DM10 domain and the EF-hand motif. Circular dichroism spectroscopy revealed that the secondary structure of EFHC1C is composed by 34% of alpha-helices and 17% of beta-strands. Size exclusion chromatography and mass spectrometry showed that under oxidizing condition EFHC1C dimerizes through the formation of disulfide bond. Tandem mass spectrometry (MS/MS) analysis of peptides generated by trypsin digestion suggests that the Cys575 is involved in intermolecular S-S bond. In addition, DTNB assay showed that each reduced EFHC1C molecule has one accessible free thiol. Isothermal titration calorimetry (ITC) showed that while the interaction between Ca(2+) and EFHC1C is enthalpically driven (DeltaH=-58.6 to -67 kJ/mol and TDeltaS=-22.5 to -31 kJ/mol) the interaction between Mg(2+) and EFHC1C involves an entropic gain, and is approximately 5 times less enthalpically favorable (DeltaH=-11.7 to -14 kJ/mol and TDeltaS=21.9 to 19 kJ/mol) than for Ca(2+) binding. It was also found that under reducing condition Ca(2+) or Mg(2+) ions bind to EFHC1C in a 1/1 molar ratio, while under oxidizing condition this ratio is reduced, showing that EFHC1C dimerization blocks Ca(2+) and Mg(2+) binding.

Expression Profile and Distribution of Efhc1 Gene Transcript During Rodent Brain Development

One of the putative causative genes for juvenile myoclonic epilepsy (JME) is EFHC1. We report here the expression profile and distribution of Efhc1 messenger RNA (mRNA) during mouse and rat brain development. Real-time polymerase chain reaction revealed that there is no difference in the expression of Efhc1 mRNA between right and left hemispheres in both species. In addition, the highest levels of Efhc1 mRNA were found at intra-uterine stages in mouse and in adulthood in rat. In common, there was a progressive decrease in Efhc1 expression from 1-day-old neonates to 14-day-old animals in both species. In situ hybridization studies showed that rat and mouse Efhc1 mRNAs are expressed in ependymal cells of ventricle walls. Our findings suggest that Efhc1 expression is more important during initial phases of brain development and that at this stage it could be involved in key developmental mechanisms underlying JME.

Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8

The effects of aluminum (Al) on the activities of antioxidant enzymes and ferritin expression were studied in cell suspension cultures of two varieties of Coffea arabica, Mundo Novo and Icatu, in medium with pH at 5.8. The cells were incubated with 300 µM Al3+, and the Al speciation as Al3+ was 1.45% of the mole fraction. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) were increased in Mundo Novo, whereas glutathione reductase (GR) and guaiacol peroxidase (GPOX) activities remained unchanged. SOD, GR, and GST activities were increased in Icatu, while CAT activity was not changed, and GPOX activity decreased. The expression of two ferritin genes (CaFer1 and CaFer2) were analyzed by Real-Time PCR. Al caused a downregulation of CaFER1 expression and no changes of CaFER2 expression in both varieties. The Western blot showed no alteration in ferritin protein levels in Mundo Novo and a decrease in Icatu. The differential enzymes responses indicate that the response to Al is variety-dependent.

A Interleucina 1-beta mostra uma ação protetora na fase aguda do modelo de epilepsia induzido pela pilocarpina

INTRODUCTION: There is contradictory information regarding the of effects il1β and il1rn in epilepsy. We aimed to evaluate the effect of silencing both genes in the acute phase of the pilocarpine-induced epilepsy model. METHODS: We used RNA interference in order to achieve gene silencing. RESULTS: We obtained significant gene silencing in the central nervous system. In addition, we observed phenotypic effects including differences in mortality rates of animals 5 days after pilocarpine injections. CONCLUSION: Our results indicate that il1β seems to have a protective effect in the acute phase of the pilocarpine-induced epilepsy model.