Thermostable Lichenase from Clostridium thermocellum as a Host Protein in the Domain Insertion Approach.

Clostridium thermocellum lichenase (endo-ß-1,3;1,4-glucan-D-glycosyl hydrolase, EC 3.2.1.73 (P29716)) has been tested for the insertion of two model fluorescent proteins (EGFP and TagRFP) into two regions of this enzyme. Functional folding of the resulting proteins was confirmed by retention of lichenase activity and EGFP and TagRFP fluorescence. These results convincingly demonstrate that (i) the two experimentally selected lichenase loop regions may serve as the areas for domain insertion without disturbing enzyme folding in vivo; (ii) lichenase permits not only single but also tandem insertions of large protein domains. High specific activity, outstanding thermostability, and efficient in vitro refolding of thermostable lichenase make it an attractive new host protein for the insertional fusion of domains in the engineering of multifunctional proteins.

Modern Approaches to Studies of New Osteogenic Biomaterials on the Model of Regeneration of Critical-Size Cranial Defects in Rats.

Osteoinductive characteristics of new osteoplastic materials based on demineralized bone matrix of xenogenic origin with high and controlled degree of purification were studied on the model of regeneration of critical-size cranial defects in rats using modern approaches, including histological analysis, evaluation of morphological parameters of the bone tissue obtained by micro-computed tomography, and estimation of bone tissue growth rate using in vivo fluorochrome label. Demineralized bone matrix and, to a much greater extent, its activated form containing modified recombinant growth factor rhBMP-2 with high content of the dimeric form exhibited osteoinductive activity.

[An association study of polymorphisms in HTR2A, BDNF and SLC6A4 genes with paranoid schizophrenia and suicidal behavior].

We have developed a biochip for the analysis of candidate genes for schizophrenia. Using this biochip, allele and genotype frequencies for the polymorphisms of HTR2A, BDNF and SLC6A4 genes in 198 patients with schizophrenia and 192 healthy individuals have been obtained. The allele T of the HTR2A polymorphism rs6314 was identified as protective against the development of paranoid schizophrenia (p=0,014). An analysis of gene-gene interactions using the Multifactor-Dimensionality Reduction (MDR) algorithm has shown a statistically significant association of combined genotypes rs6311 G/-, rs6313 C/-, rs6314 C/C, rs7997012 G/- with the disease (p=0.019). Also it has been shown that the G/G genotype of the polymorphism rs6311 (p=0.013) and the C/C genotype of the polymorphism rs6313 (p=0.008) in the HTR2A gene are associated with the suicide attempt in schizophrenic patients. Correspondingly, an A allele, А/- genotypes of the polymorphism rs6311 G>A and a T allele, T/- genotypes of the polymorphism rs6313 C>T were found to be less frequent in schizophrenic patients with a history of suicide attempt than in schizophrenic patients without a history of suicide attempt, thus suggesting their protective role in the development of suicidal behavior. The results confirm the hypothesis that the HTR2A plays an important role in the etiology of schizophrenia and suicidal behavior.

[Analysis of genetic predisposition to pulmonary tuberculosis in native Russians].

Tuberculosis (TB) is one of the most important concerns of public health. There is evidence suggesting that genetic status is responsible for predisposition to infectious diseases including TB. To determine genetic risk factors of TB development, the frequencies of polymorphisms of genes CYP1A1, CYP2D6, CYP2C9, CYP2C 19, GSTT1, GSTM1, NAT2, MDR1, and NRAMP1 in 73 TB patients and 352 healthy individuals were determined by allele-specific hybridization using microarray technology. The TB patients have shown a significant increase in the frequency of the null GSTT1 genotype (OR = 3.26, 95% CI = 1.91 - 5.55, p = = 0.000028) as well as the double null GSTT1/GSTM1 genotype (OR = 4.05, 95% CI = 2.14 -7.65, p = = 0.000034) compared to the group of healthy donors. It was shown that the NAT2*5/*5 genotype in combination with the "null" GSTT1 and the double "null" GSTT1/GSTM1 genotypes was observed significantly more often in the TB patients than in the control sample. Thus the examined GSTT1, GSTM1 and NAT2 gene polymorphisms may potentially alter the risk of TB development in ethnic Russians and are of interest for further research using larger cohorts of patients.

[Association of NAT2 polymorphism with risks to develop psoriasis and various dermatological diseases in Moscow population].

Ruacetyltransferase 2 (NAT2) is one of key enzymes of the second phase of biotransformation that metabolize genotoxic compounds such as carcinogens and mutagens in different types of cells. There is a correlation between the decreasing activity of NAT2 gene product and the sensitivity to harmful environmental factors that increase the risk of occurrence of different multifactorial diseases, including dermatological ones like psoriasis. We developed the NAT2-biochip for 17 SNPs. The biochip was been tested on 279 clinical DNA samples from 180 patients with psoriasis and 99 healthy individuals, residents of Moscow. We found only six SNPs that were significant for European populations (282C > T, 341T > C, 481C > T, 590G > A, 803A > G and 857G > A). The analysis in psoriasis group did not show any genotype association. The increase in frequency of a slow acetylation phenotype in group of patients with type II psoriasis and in group of patients with normosthenic constitution, in comparison with control group (OR = 1.76,p = 0.177 and OR = 2.07,p = 0.050, respectively) has been revealed. The results for patients smoking one or more pack of cigarettes per day, and daily alcohol drinking in comparison with the control showed an increase in frequency for the genotype 341C/C, 481T/T, 803G/G (OR = 7.42, p = 0.008 and OR = 106.11, p = 0.003, respectively). We also found an increase of frequency of genotype 341T/T, 481C/C, 590A/-, 803A/A in patients with side reactions to medical products comparing with group of healthy donors (OR = 2.05, p = 0.099). Thus, the present data show that the certain NAT2 genotypes and some styles of life can be considered as risk factors of psoriasis development in this muscovite population.

[Association of xenobiotic-metabolizing gene polymorphisms with childhood atopic diseases in Russian patients from the Republic of Bashkortostan].

Enzymes of biotransformation system involved in the metabolism of exogenous and endogenous compounds are effective mechanism of protection from negative environmental factors. Decreasing activity or insufficient synthesis of biotransformation system enzymes caused by genetic polymorphism form the risk of various complex diseases, including atopic. Using allele-specific hybridization on the biochip the frequencies of xenobiotic-metabolizing gene polymorphisms in Russian children with bronchial asthma, allergic rhinitisand healthy donors from the Republic of Bashkortostan have been determined. The analysis of polymorphisms in CYP1A1, GSTT1, GSTM1, NAT2, MTHFR, CYP2C9 and CYP2C19 genes didn't reveal any association with atopic diseases. The frequencies of CYP2D6*1934G/G genotype and CYP2D6*1934G allele were significantly higher among boys with rhinitis symptoms than in control group.

[Genetic polymorphism in GST, NAT2, and MTRR and susceptibility to childhood acute leukemia].

It is known that presence of xenobiotic-metabolizing gene polymorphisms in some cases correlates with hereditary predisposition to the oncological diseases. In the present work the frequencies of xenobiotic-metabolizing gene polymorphisms in 332 children with the diagnosis acute lymphoblastic leukemia (ALL), 71 children with the diagnosis acute myeloblastic leukemia (AML) and 490 healthy donors have been determined using allele-specific hybridization on the biochip. Statistically significant increase in the frequency of GSTT1 "null" genotype (OR = 1.9, p = 4.7E-5) and GSTT1/GSTM1 double "null" genotype (OR = 3.1, p = 2.5E-8) in children with acute leukemia relative to healthy donors group has been revealed. Also 1.8-fold increase in the frequency of NAT2 genotype 341T/T, 481C/C, 590G/G in children with acute leukemia relative to healthy donors group (p = 0.026) has been recognized. Analysis of gene-gene interactions has showed that in patients with acute leukemia genotype NAT2 341T/T, 481C/C, 590G/G in combination with GSTT1 "null" and/or GSTM1 "null" genotype is significantly more frequent than in population control. Besides the reduction of MTRR genotype 66G/G frequency in girls with acute leukemia relative to female healthy donors has been found (OR = 0.50, p = 0.0015). Analysis of gene-gene interactions has shown that the presence of GSTT1 "null" and/or GSTM1 "null" genotype in combination with MTRR genotype 66A/- may consider as risk factor of acute leukemia in girls. Thus, the studied polymorphic variants of genes GSTT1, GSTM1, NAT2 and MTRR can modulate the risk of childhood acute leukemia, residents of European part of Russia.

[Identification of functionally significant mutations in NAT2 gene using biological microchips].

The product of gene NAT2 (N-acetyltransferase 2) is involved in the biotransformation system and participates in detoxication of some arylamine derivatives (in particular 2-aminofluorene, 4-aminobiphenyl and 4-naphthylamine) which are strongly mutagenic and carcinogenic. It also renders toxicological and pharmacological influence on a metabolism of medical products metabolized by the enzyme. We developed a microchip for detection of 16 functionally significant mutations coding 36 alleles of gene NAT2. Combinations of these alleles allow us to reveal more than 660 genotypes, which can be divided into four groups according acetylation phenotype: "fast" (R/R), "intermediate" (R/S), "slow" (S/S) and group with average or slow acetylating (R/S or S/S) alleles. The groups "R/S or S/S" include alleles, formed by a combination of 7 mutations (191G/A, 282C/T, 341T/C, 481C/T, 590G/A, 803A/G, 857G/A), theirs cis-trans position can be revealed by restriction analysis. In 37 of 71 DNA samples we unequivocally defined NAT2-genotypes, and other 34 samples have been characterized by more than two genotypes. 16 samples out of 34 had acetylation phenotype of group "R/S or S/S", which is characterized by the following combination of mutations: 282C/T, 341T/C, 481C/T, 590G/A and 803A/G. Thus, the developed biochip is a convenient screening method for primary detection of the majority of polymorphic replacements in gene NAT2.

Effects of external transport on discrimination between perfect and mismatch duplexes on gel-based oligonucleotide microchips.

Using hydrogel-based oligonucleotide microchips developed previously for the choice of drugs during leukemia treatment and the other diseases, it is shown that the acceleration of external transport by mixing buffer solution with peristaltic pump not only enhances the observable fluorescence signals, but also improves significantly the discrimination between perfect and mismatch duplexes at the intermediate stage of hybridization on the oligonucleotide microchips. The discrimination efficiency for a given hybridization time grows monotonously with the frequency of flow pulsations. The mixing with frequency 10 Hz accelerates the hybridization rate approximately thrice and improves the discrimination efficiency 1.5-2.5 times higher for overnight hybridization. To study these effects, we have developed the special peristaltic pump mixing solution in a hybridization chamber of 35 mul in volume (area approximately 1 x 1 cm(2) and height 0.3 mm). We present also the brief theoretical summary for the interpretation and assessment of the observed experimental features.

[Comparative analysis of N-acetylation polymorphism in humans as determined by phenotyping and genotyping].

The N-acetylation polymorphisms of volunteers from the Moscow population analyzed by phenotyping and genotyping have been compared. The ratios between the proportions of fast acetylators (FAs) and slow acetylators (SAs) estimated by phenotyping and genotyping do not differ significantly from each other (47 and 44%, respectively). The absolute acetylation rate widely varies in both FAs and SAs. The NAT2 genotype and allele frequencies in the population sample have been calculated. The most frequent alleles are NAT2*4 (a "fast" allele), NAT2*5, and NAT2*6 ("slow" alleles); the most frequent genotypes are NAT2*5/*5, NAT2*4/*6, and NAT2*4/*5. Comparative analysis of N-acetylation polymorphism estimated by phenotyping and genotyping in the same subjects has shown a complete concordance between the phenotype and genotype in only 62 out of 75 subjects (87%). Comparative characteristics and presumed applications of the two approaches (quantitative estimation of acetylation rate and qualitative determination of the acetylator genotype) to the identification of individual acetylation status are presented.