Jucimara Colombo

Polymorphisms of the DNA repair genes XRCC1 and XRCC3 in a Brazilian population

In several DNA repair genes, polymorphisms may result in reduced repair capacity, which has been implicated as a risk factor for various types of cancer. The frequency of the polymorphic alleles varies among populations, suggesting an ethnic distribution of genotypes. We genotyped 300 healthy Southeastern Brazilian individuals (262 of European ancestry and 38 of African ancestry) for polymorphisms of codons 194 and 399 of the XRCC1 base excision repair pathway gene and of codon 241 of the XRCC3 homologous recombination repair pathway gene. The allele frequencies were 0.07 for the Arg194Trp and 0.33 for the Arg399Gln codons of the XRCC1 gene and 0.35 for the Thr241Met codon of the XRCC3 gene. The genotypic frequencies were within Hardy-Weinberg equilibrium. These frequencies showed ethnic variability when compared with those obtained for different populations from several countries.

Gene expression analysis reveals novel altered genes in nasal polyps

Nasal polyposis (NP) is a chronic inflammatory disease of the nasal mucosa characterized by the infiltration of inflammatory cells, mainly eosinophils. Although nasal polyposis occurs in 4% of the population, its physiopathology remains unclear. The aim of this study was to identify and characterize differentially expressed genes that can be used in the prognosis, treatment and elucidation of this physiopathology. To identify novel genes differentially expressed in NP, we applied real-time quantitative PCR to 11 NP samples and to a pool of total RNA from a subset of 13 normal nasal mucosa samples from human autopsies. For selecting genes, the methylated CpG island amplification technique was used. Five differentially methylated clones (ATP2A1, NOVA1, PLCD3, SOLH and TGFβI) were identified. However, these genes presented methylated CpG islands between exons, i.e., not in the promoter regions of the genes. Thus, as shown by real-time PCR, the ATP2A1, SOLH, PLDC3 and TGFβI genes were overexpressed in NP. The genes identified in this study are probably involved in some stage of the process of formation and development of nasal polyposis, as they were highly expressed in the nasal polyp samples.

Expression, purification and molecular analysis of the human ZNF706 protein.

BackgroundThe ZNF706 gene encodes a protein that belongs to the zinc finger family of proteins and was found to be highly expressed in laryngeal cancer, making the structure and function of ZNF706 worthy of investigation. In this study, we expressed and purified recombinant human ZNF706 that was suitable for structural analysis in Escherichia coli BL21(DH3).FindingsZNF706 mRNA was extracted from a larynx tissue sample, and cDNA was ligated into a cloning vector using the TOPO method. ZNF706 protein was expressed according to the E. coli expression system procedures and was purified using a nickel-affinity column. The structural qualities of recombinant ZNF706 and quantification alpha, beta sheet, and other structures were obtained by spectroscopy of circular dichroism. ZNF706s structural modeling showed that it is composed of α-helices (28.3%), β-strands (19.4%), and turns (20.9%), in agreement with the spectral data from the dichroism analysis.ConclusionsWe used circular dichroism and molecular modeling to examine the structure of ZNF706. The results suggest that human recombinant ZNF706 keeps its secondary structures and is appropriate for functional and structural studies. The method of expressing ZNF706 protein used in this study can be used to direct various functional and structural studies that will contribute to the understanding of its function as well as its relationship with other biological molecules and its putative role in carcinogenesis.