Comparative Analysis of Gene Expression Profiles Involved in Calcium Signaling Pathways Using the NLVH Animal Model of Schizophrenia

In this study, we evaluated the expression profile changes of genes that intervene in the calcium signaling pathway, in young and adult Wistar rats, using the animal model of neonatal lesion in ventral hippocampus (NLVH) (a recognized animal model for schizophrenia) and compared to the group of control animals (Sham). Through microarray technology, gene expression profiles were obtained from the three brain areas (nucleus accumbens, prefrontal cortex, and hippocampus) of young male Wistar rats (45 days) and adults (90 days) whether or not subjected to NLVH. The calcium signaling pathway reported a greater number of differentially expressed genes with z-score two values, > 2 (over-expression) and < - 2 (under-expression), in the three evaluated areas. The comparative analyses of this approach were performed in juvenile and adult rats with ventral hippocampal lesion in neonate rats (NLVH). NLVH influenced change expressions in various genes involved in Ca²⁺ homeostasis, including Cacna1d, Atp2a2, Adcy2, Ppp3cb, and Ptk2b. The expression of Adcy2, Ppp3cb, and Ptk2b genes changed in both age groups; therefore, the study of gene expression profiles between juvenile and adult rats may help to understand the molecular mechanisms of schizophrenia.

Detection of anti-streptococcal, antienolase, and anti-neural antibodies in subjects with early-onset psychiatric disorders

INTRODUCTION

Infection with group A Streptococcus (StrepA) can cause post-infectious sequelae, including a spectrum of childhood-onset obsessive-compulsive (OCD) and tic disorders with autoimmune origin (PANDAS, Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections). Until now, no single immunological test has been designed that unequivocally diagnoses these disorders. In this study, we assessed the detection of serum antibodies against human brain enolase (AE), neural tissue (AN) and Streptococcus (AS) as a laboratory tool for the diagnosis of early-onset psychiatric disorders.

METHODOLOGY

Serum antibodies against human brain enolase, total brain proteins, and total proteins from StrepA were detected by ELISA in 37 patients with a presumptive diagnosis of PANDAS and in 12 healthy subjects from Mexico and Cuba.

RESULTS

The antibody titers against human brain enolase (AE) and Streptococcal proteins (AS) were higher in patients than in control subjects (t-student, tAE=-2.17, P=0.035; tAS=-2.68, P=0.01, n=12 and 37/group, df=47, significance level 0.05), while the neural antibody titers did not differ between the two groups (P(t)=0.05). The number of subjects (titers> meancontrol + CI95) with simultaneous seropositivity to all three antibodies was higher in the patient group (51.4%) than in the control group (8.3%) group (X2=5.27, P=0.022, df=1, n=49).

CONCLUSIONS

The simultaneous detection of all three of these antibodies could provide valuable information for the etiologic diagnosis of individuals with early-onset obsessive-compulsive disorders associated with streptococcal infection and, consequently, for prescribing suitable therapy.

Maternal admixture and population structure in Mexican-Mestizos based on mtDNA haplogroups

The maternal ancestry (mtDNA) has important applications in different research fields, such as evolution, epidemiology, identification, and human population history. This is particularly interesting in Mestizos, which constitute the main population in Mexico (∼93%) resulting from post-Columbian admixture between Spaniards, Amerindians, and African slaves, principally. Consequently, we conducted minisequencing analysis (SNaPshot) of 11 mitochondrial single-nucleotide polymorphisms in 742 Mestizos of 10 populations from different regions in Mexico. The predominant maternal ancestry was Native American (92.9%), including Haplogroups A, B, C, and D (47, 23.7, 15.9, and 6.2%, respectively). Conversely, European and African ancestries were less frequent (5.3 and 1.9%, respectively). The main characteristics of the maternal lineages observed in Mexican-Mestizos comprised the following: 1) contrasting geographic gradient of Haplogroups A and C; 2) increase of European lineages toward the Northwest; 3) low or absent, but homogeneous, African ancestry throughout the Mexican territory; 4) maternal lineages in Mestizos roughly represent the genetic makeup of the surrounding Amerindian groups, particularly toward the Southeast, but not in the North and West; 5) continuity over time of the geographic distribution of Amerindian lineages in Mayas; and 6) low but significant maternal population structure (FST  = 2.8%; P = 0.0000). The average ancestry obtained from uniparental systems (mtDNA and Y-chromosome) in Mexican-Mestizos was correlated with previous ancestry estimates based on autosomal systems (genome-wide single-nucleotide polymorphisms and short tandem repeats). Finally, the comparison of paternal and maternal lineages provided additional information concerning the gender bias admixture, mating patterns, and population structure in Mestizos throughout the Mexican territory.

Gene expression profiles of nucleus accumbens, prefrontal cortex and hippocampus in an animal model of schizophrenia: proposed candidate genes

INTRODUCTION

It has been suggested that schizophrenia may be induced by “accidents” or injuries that occur during early brain development and result in a reduction of the neural connections in different regions. In this study, we evaluated differences in the expression of brain genes using a recognized experimental prototype of schizophrenia: the animal model of ventral hippocampal lesion in neonate rats (VHLN) compared to control animals.

METHODS

Using microarray technology, we obtained gene expression profiles of three brain areas (nucleus accumbens, prefrontal cortex and hippocampus) of juvenile (45 days) and adult (90 days) Wistar male rats that underwent either VHLN or sham VHLN.

RESULTS

Based on three criteria: 1) expression in more than one brain area, 2) participation in cellular pathways relevant to the central nervous system (CNS), 3) Z-score values >2 (overexpression) and <-2 (underexpression), we found overexpression of the ppp3cb, dctn1, jag1, ide, limk2 and cpz genes and underexpression of chrna4 and sod1.

CONCLUSIONS

Two of the genes proposed in this paper, limk2 and cpz, have not been previously associated with schizophrenia, so future studies will be necessary to understand their possible role in the pathogenesis of this disease.

Transferrin regulates mRNA levels of a gene involved in iron utilization in Entamoeba histolytica

Entamoeba histolytica is a human pathogen, which can survive using haemoglobin (Hb) as only iron supply. Two probable haemophores (Ehhmbp26 and Ehhmbp45) are involved in iron acquisition in this parasite. However, mechanisms related to their transcriptional regulation have not been studied yet. In the present work, transcriptional profiles of both genes were evaluated in trophozoites cultures grown with different iron sources. ehhmbp26 gene was repressed totally by free iron, whereas ehhmbp45 gene showed clearly detectable mRNA levels. Expression profiles for both genes were significantly increased under iron privation condition. Interestingly, ehhmbp26 transcript was highly expressed by Holo-transferrin presence. This induction appears to be independent of direct contact between these proteins, because, in vitro assays evidenced that Ehhmbp26 protein was unable to bind this metalloprotein. Besides, in silico analysis of promoter nucleotide sequences of ehhmbp26 and ehhmbp45 genes revealed some distinctive core promoter elements described in E. histolytica and T-rich regions. Taking altogether these data suggest in E. histolytica dissimilar transcriptional mechanisms involved on iron acquisition control the expression of these genes, and they are unlike to those previously described for instance: in bacteria. Our findings evidenced this pathogen regulates the expression of ehhmbp26 and ehhmbp45 genes depending on the available iron supply, always ensuring the success of its infective process.

Transcriptional profile of the homologous recombination machinery and characterization of the EhRAD51 recombinase in response to DNA damage in Entamoeba histolytica

Background

In eukaryotic and prokaryotic cells, homologous recombination is an accurate mechanism to generate genetic diversity, and it is also used to repair DNA double strand-breaks. RAD52 epistasis group genes involved in recombinational DNA repair, including mre11, rad50, nsb1/xrs2, rad51, rad51c/rad57, rad51b/rad55, rad51d, xrcc2, xrcc3, rad52, rad54, rad54b/rdh54 and rad59 genes, have been studied in human and yeast cells. Notably, the RAD51 recombinase catalyses strand transfer between a broken DNA and its undamaged homologous strand, to allow damaged region repair. In protozoan parasites, homologous recombination generating antigenic variation and genomic rearrangements is responsible for virulence variation and drug resistance. However, in Entamoeba histolytica the protozoan parasite responsible for human amoebiasis, DNA repair and homologous recombination mechanisms are still unknown.

Results

In this paper, we initiated the study of the mechanism for DNA repair by homologous recombination in the primitive eukaryote E. histolytica using UV-C (150 J/m²) irradiated trophozoites. DNA double strand-breaks were evidenced in irradiated cells by TUNEL and comet assays and evaluation of the EhH2AX histone phosphorylation status. In E. histolytica genome, we identified genes homologous to yeast and human RAD52 epistasis group genes involved in DNA double strand-breaks repair by homologous recombination. Interestingly, the E. histolytica RAD52 epistasis group related genes were differentially expressed before and after UV-C treatment. Next, we focused on the characterization of the putative recombinase EhRAD51, which conserves the typical architecture of RECA/RAD51 proteins. Specific antibodies immunodetected EhRAD51 protein in both nuclear and cytoplasmic compartments. Moreover, after DNA damage, EhRAD51 was located as typical nuclear foci-like structures in E. histolytica trophozoites. Purified recombinant EhRAD51 exhibited DNA binding and pairing activities and exchanging reactions between homologous strands in vitro.

Conclusion

E. histolytica genome contains most of the RAD52 epistasis group related genes, which were differentially expressed when DNA double strand-breaks were induced by UV-C irradiation. In response to DNA damage, EhRAD51 protein is overexpressed and relocalized in nuclear foci-like structures. Functional assays confirmed that EhRAD51 is a bonafide recombinase. These data provided the first insights about the potential roles of the E. histolytica RAD52 epistasis group genes and EhRAD51 protein function in DNA damage response of this ancient eukaryotic parasite.