Molecular chaperones facilitate soluble expression of recombinant non-toxic mutant CRM197 of diphtheria toxin in Escherichia coli / 生物工程学报

Diphtheria toxin is an ADP-ribosyltransferase toxic to human cells. Mutation of the active site in its catalytic domain eliminates the toxicity, but retains its immunogenicity. A non-toxic mutant of diphtheria toxin known as CRM197 protein has become an ideal carrier protein for conjugate vaccines. CRM197 can further improve its immunogenicity by cross-linking with other antigens, so it has good potential to find broad applications. Unfortunately, inclusion bodies are easily formed during the expression of recombinant CRM197 protein in Escherichia coli, which greatly reduces its yield. In order to address this problem, pG-KJE8 vector carrying molecular chaperones and plasmid pET28a-CRM197, were co-expressed in Escherichia coli. The results showed that the recombinant CRM197 protein was successfully expressed and appeared largely in inclusion bodies. The molecular chaperones DnaK, DnaJ, GrpE, GroES and GroEL5 expressed can facilitate correct and rapid folding of CRM197. Furthermore, it can also improve the recovery rate of soluble CRM197 protein. The soluble expression of CRM197 was maximized upon addition of 1.0 mmol/L IPTG, 0.5 mg L-arabinose, 5.0 ng/mL tetracycline and induction at 20oC for 16 h. The soluble CRM197 protein shows good immunoreactivity, demonstrating the molecular chaperones expressed from pG-KJE8 facilitated the soluble expression of CRM197 protein in E. coli.

Vitamina D, miR-21 y marcadores de apoptosis en pacientes con diabetes tipo I / Vitamin D, miR-21 and apoptosis markers in patients with type 1 diabetes

La diabetes Tipo 1 (DT1) es una compleja enfermedad autoinmune con una etiología aún desconocida. La vitamina D ha sido ampliamente estudiada debido a su potencial terapéutico en los potenciales nuevos casos de DT1. Por otra parte, los microARNs (miRs) han sido propuestos como posibles biomarcadores en diversos procesos biológicos como en la apoptosis e inflamación. El objetivo de este estudio fue evaluar el efecto de la suplementación con vitamina D sobre el perfil de expresión del miR-21 y marcadores de apoptosis tales como: BCL2, STAT3, TIPE2 y DAXX, en células mononucleares periféricas provenientes de pacientes con DT1 y sujetos controles. RESULTADOS: El perfil de expresión de miR-21 se encontró disminuido en los pacientes con DT1 en comparación con los controles. La expresión relativa de BCL2 se encontró aumentada en controles al comparar con pacientes DT1 en todas las condiciones experimentales. La expresión relativa de DAXX mostró un perfil de expresión diferencial al comparar pacientes con DT1 versus controles (p=0.006). CONCLUSIÓN: El estímulo con vitamina D parece tener un posible efecto regulador sobre los genes BCL2 y DAXX.

Type 1 diabetes (T1D) is a complex chronic autoimmune disease. Vitamin D has been one of the most studied therapeutic potential outbreaks related to T1D. Specific miRNAs have been proposed as potential biomarkers in several biological processes as apoptosis and inflammation. The aim of this study was to evaluate the effect of vitamin D on the expression profiles of miR-21 and apoptotic markers BCL2, STAT3, TIPE2 and DAXX, in PBMCs from T1D patients and control subjects. RESULTS: miR-21 expression was increased in controls regarding T1D patients. BCL2 was increased in controls compared to T1D patients in all experimental conditions. DAXX showed different expression patterns between T1D patients and controls (p=0.006). CONCLUSION: Vitamin D showed a possible regulation effect on apoptosis markers mainly through the regulation of BCL2 and DAXX

Expression of epithelial-mesenchymal transition markers at the invasive front of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common malignances. In epithelial-mesenchymal transition (EMT), epithelial cells switch to mesenchymal-like cells exhibiting high mobility. This migratory phenotype is significant during tumor invasion and metastasis. Objective : The aim of this study is to evaluate the expression of the EMT markers E-cadherin, N-cadherin and vimentin in OSCC. Material and Methods : Immunohistochemical detection of E-cadherin, N-cadherin and vimentin was performed on 20 OSCC samples. Differences in the expression of each protein at the invasive front (IF) and in the central/superficial areas (CSA) of the tumor were assessed. Differences in the expression of each protein at the IF of both histologically high- and low-invasive OSCCs were evaluated. Associations among expression of proteins at the IF were assessed. Correlations between the expression levels of each protein at the IF and the tumor stage and clinical nodal status were also evaluated. Results : Reduced expression of E-cadherin was detected in 15 samples (75%). E-cadherin expression was reduced at the IF when compared to the CSA and in high-invasive tumors when compared to low-invasive tumors. All samples were negative for N-cadherin, even though one sample showed an inconspicuous expression. Positive expression of vimentin was observed in 6 samples (30%). Nevertheless, there was no difference in vimentin expression between the IF and the CSA regions or between the low- and high-invasive tumors. Furthermore, no association was observed among protein expression levels at the IF. Finally, no correlations were observed between each protein’s expression levels and tumor stage or clinical nodal status. Conclusions : Reduced E-cadherin expression at the IF and its association with histological invasiveness suggest that this protein is a noteworthy EMT marker in OSCC. Although vimentin was also detected as an EMT marker, its expression was ...

Genetic evaluation for TOR1-A (DYT1) in Brazilian patients with dystonia / Avaliação genética para TOR1-A (DYT1) em pacientes brasileiros com distonia

Several genes have been mapped in families or in sporadic cases of dystonia. TOR1-A (DYT1) gene was linked to isolated dystonia. Objective To associate clinical information of patients with dystonia with the TOR1-A gene mutations. Method Eighty-eight patients with dystonia in cervical area (focal, segmental, multifocal and generalized) were recruited at Movement Disorders Clinic of Hospital de Clínicas of the Federal University of Paraná between June of 2008 and June of 2009. They were submitted to the clinical evaluation. DNA was extract from blood and submitted at analysis to TOR1-A mutations by PCR according standard protocols. Results Two patients had c.907GAGdel mutation on TOR1-A gene. These patients, with familial history of dystonia, started his symptoms by legs and had secondary generalization. Conclusion We can suggest that analysis for TOR1-A mutations should be performed only in patients with early onset, generalized and familial dystonia. .

Tem sido mapeada uma série de genes em pacientes com distonia. O gene TOR1-A (DYT1) foi associado a casos de distonia primária. Objetivo Associar os achados clínicos dos pacientes com distonia com mutações em TOR1-A. Método Foram selecionados 88 pacientes com distonia na região cervical (focal, segmentar, multifocal e generalizada) no Setor de Distúrbios do Movimento do Hospital de Clínicas da Universidade Federal do Paraná entre junho de 2008 e junho de 2009. Esses pacientes foram submetidos à avaliação clínica. O DNA foi extraído do sangue periférico e submetido à análise para mutações em TOR1-A através de protocolos padronizados. Resultados A mutação c.907GAGdel foi encontrada em duas pacientes. Ambas tinham história familiar de distonia e iniciaram seus sintomas pelos membros inferiores, evoluindo com generalização. Conclusão Podemos sugerir que a análise para mutações em TOR1-A deve ser realizada em pacientes com distonia de inicio precoce, história familiar e generalização. .

Revisiting steroid treatment for septic shock: molecular actions and clinical effects - a review

Corticosteroids are widely used to treat a diversity of pathological conditions including allergic, autoimmune and some infectious diseases. These drugs have complex mechanisms of action involving both genomic and non-genomic mechanisms and interfere with different signal transduction pathways in the cell. The use of corticosteroids to treat critically ill patients with acute respiratory distress syndrome and severe infections, such as sepsis and pneumonia, is still a matter of intense debate in the scientific and medical community with evidence both for and against its use in these patients. Here, we review the basic molecular mechanisms important for corticosteroid action as well as current evidence for their use, or not, in septic patients. We also present an analysis of the reasons why this is still such a controversial point in the literature.

Induction of unfolded protein response during neuronal induction of rat bone marrow stromal cells and mouse embryonic stem cells

When we treated rat bone marrow stromal cells (rBMSCs) with neuronal differentiation induction media, typical unfolded protein response (UPR) was observed. BIP/GRP78 protein expression was time-dependently increased, and three branches of UPR were all activated. ATF6 increased the transcription of XBP1 which was successfully spliced by IRE1. PERK was phosphorylated and it was followed by eIF2alpha phosphorylation. Transcription of two downstream targets of eIF2alpha, ATF4 and CHOP/GADD153, were transiently up-regulated with the peak level at 24 h. Immunocytochemical study showed clear coexpression of BIP and ATF4 with NeuN and Map2, respectively. UPR was also observed during the neuronal differentiation of mouse embryonic stem (mES) cells. Finally, chemical endoplasmic reticulum (ER) stress inducers, thapsigargin, tunicamycin, and brefeldin A, dose-dependently increased both mRNA and protein expressions of NF-L, and, its expression was specific to BIP-positive rBMSCs. Our results showing the induction of UPR during neuronal differentiations of rBMSCs and mES cells as well as NF-L expression by ER stress inducers strongly suggest the potential role of UPR in neuronal differentiation.

A new method for purification of functional recombinant GST-cyclophilin A protein from E. coli.

The expression of glutathione-S-transferase (GST) fusion protein is extensively utilized in the study of protein-protein interactions. In the commonly used purification method, the overexpressed GST fusion protein is bound to the glutathione (GSH)-coupled resins via affinity chromatography, and then eluted by an excessive quantity of reduced GSH. However, this technique has certain limitations, such as low product purity, retention of GSH in the sample, as well as relatively high cost. To overcome these limitations, in this study, elution buffer containing 2% formic acid was utilized rather than GSH to elute the GST-fusion protein, and thereafter the acidic samples were neutralized using collecting buffer. By using this method, highly purified GST-cyclophilin A (CypA) fusion protein was obtained, without affecting the structural and functional characteristics such as PPIase and chaperone activities. Moreover, the procedure is also cost-effective, due to the low cost of formic acid as compared with GSH.

Molecular chaperones: the modular evolution of cellular networks.

Molecular chaperones play a prominent role in signaling and transcriptional regulatory networks of the cell. Recent advances uncovered that chaperones act as genetic buffers stabilizing the phenotype of various cells and organisms and may serve as potential regulators of evolvability. Chaperones have weak links, connect hubs, are in the overlaps of network modules and may uncouple these modules during stress,which gives an additional protection for the cell at the network-level. Moreover,after stress chaperones are essential to re-build inter-modular contacts by their low affinity sampling of the potential interaction partners in different modules. This opens the way to the chaperone-regulated modular evolution of cellular networks,and helps us to design novel therapeutic and anti-aging strategies.

Identification of molecular markers for the oncogenic differentiation of hepatocellular carcinoma

The aim of this study was to identify molecular markers associated with oncogenic differentiation in hepatocellular carcinoma (HCC). Using an unsupervised clustering method with a cDNA microarray, HCC (T) gene expression profiles and corresponding non-tumor tissues (NT) from 40 patients were analyzed. Of total 217 genes, 72 were expressed preferentially in HCC tissues. Among 186 differentially regulated genes, there were molecular chaperone and tumor suppressor gene clusters in the Edmondson grades I and II (GI/II) subclass compared with the liver cirrhosis (LC) subclass. The Edmondson grades III and IV (GIII/IV) subclass with a poor survival (P = 0.0133) contained 122 differentially regulated genes with a cluster containing various metastasis- and invasion-related genes compared with the GI/II subclass. Immunohistochemical analysis revealed that ANXA2, one of the 72 genes preferentially expressed in HCC, was over-expressed in the sinusoidal endothelium and in malignant hepatocytes in HCC. The genes identified in the HCC subclasses will be useful molecular markers for the genesis and progression of HCC. In addition, ANXA2 might be a novel marker for tumor angiogenesis in HCC.

Cop-like operon: Structure and organization in species of the Lactobacillale order

Copper is an essential and toxic trace metal for bacteria and, therefore, must be tightly regulated in the cell. Enterococcus hirae is a broadly studied model for copper homeostasis. The intracellular copper levels in E. hirae are regulated by the cop operon, which is formed by four genes: copA and copB that encode ATPases for influx and efflux of copper, respectively; copZ that encodes a copper chaperone; and copY, a copper responsive repressor. Since the complete genome sequence for E. hirae is not available, it is possible that other genes may encode proteins involved in copper homeostasis. Here, we identified a cop-like operon in nine species of Lactobacillale order with a known genome sequence. All of them always encoded a CopY-like repressor and a copper ATPase. The alignment of the cop-like operon promoter region revealed two CopY binding sites, one of which was conserved in all strains, and the second was only present in species of Streptococcus genus and L. johnsonii. Additional proteins associated to copper metabolism, CutC and Cupredoxin, also were detected. This study allowed for the description of the structure and organization of the cop operon and discussion of a phylogenetic hypothesis based on the differences observed in this operon's organization and its regulation in Lactobacillale order.

Molecular chaperones in the Paracoccidioides brasiliensis transcriptome

Paracoccidioides brasiliensis is a thermally dimorphic and a human pathogenic fungus. Our group has partially sequenced its transcriptome and generated a database of mycelial and yeast PbAESTs (P. brasiliensis assembled expressed sequence tags). In the present review we describe the identification of PbAESTs encoding molecular chaperones. These proteins, involved in protein folding and renaturation, are also implicated in several other biological processes, where the dimorphic transition is of particular interest. Another important issue concerning these proteins refers to their participation in the immunopathogenicity of infectious diseases. We have found 438 ESTs (184 in mycelium and 253 in yeast) encoding P. brasiliensis molecular chaperones and their co-chaperones, which were clustered in 48 genes. These genes were classified in families, corresponding to three small chaperones, nine HSP40s, 10 HSP60s, seven HSP70s, five HSP90s, four HSP100s, and 10 other chaperones. These results greatly increase the knowledge on P. brasiliensis molecular chaperones, since only eight of such proteins had been previously characterized.

Coordinated transcriptional regulation of calmegin, a testis-specific molecular chaperon, by histone deacetylase and CpG methyltransferase

Calmegin is a testis-specific molecular chaperon playing a key role in spermatogenesis. However, the transcriptional regulatory mechanisms for calmegin expression are entirely unknown. Herein, we revealed that calmegin is transcriptionally regulated by histone deacetylase (HDAC) and CpG methyltransferase. The cDNA microarray analysis of the human fibrosarcoma cells treated with trichostatin A (TSA) showed an increased level of calmegin mRNA. The induction of calmegin mRNA by TSA was added by the treatment with 5-aza-2'-deoxycytidine (5'Aza- dC), implying that epigenetic alterations are involved in the transcriptional repression of the gene. Moreover, chromatin immunoprecipitation assay using an anti-acetyl-histone H3 antibody exhibited that the proximal region (-152~-31) of the calmegin promoter is responsible for HDAC-mediated transcriptional repression of the gene. These results demonstrate that calmegin expression is regulated by HDAC and CpG methyltransferase in a coordinative way.