Cytogenetic Analysis of the Results of Genome Editing on the Cell Model of Parkinson's Disease.

We performed a cytogenetic analysis of the results of CRISPR/Cas9-correction of G2019S mutation in LRRK2 gene associated with Parkinson's disease. Genome editing was performed on induced pluripotent stem cells derived from fibroblasts of a patient carrying this mutation. A mosaic variant of tetraploidy 92 XXYY/46,XY (24-43% cells from various clones) was found in neuronal precursors differentiated from the induced pluripotent stem cells after gene editing procedure. Solitary cases of translocations and chromosome breaks were observed. These data confirm the importance of the development of new approaches ensuring genome stability in CRISPR/Cas9-edited cultures.

Neuroprotective Properties of Endocannabinoids N-Arachidonoyl Dopamine and N-Docosahexaenoyl Dopamine Examined in Neuronal Precursors Derived from Human Pluripotent Stem Cells.

Neuroprotective properties of endocannabinoids N-arachidonoyl dopamine (NADA) and N-docosahexaenoyl dopamine (DHDA) were examined in neuronal precursor cells differentiated from human induced pluripotent stem cells and subjected to oxidative stress. Both compounds exerted neuroprotective activity, which was enhanced by elevating the concentration of the endocannabinoids within the 0.1-10 µM range. However, both agents at 10 µM concentration showed a marked toxic effect resulting in death of ~30% of the cells. Finally, antagonists of cannabinoid receptors as well as the receptor of the TRPV1 endovanilloid system did not hamper the neuroprotective effects of these endocannabinoids.

Effect of Nerve Growth Factor on Neural Differentiation of Mouse Embryonic Stem Cells.

The cholinergic, GABAergic, and catecholaminergic neurons derived from mouse embryonic stem cells in a culture medium supplemented with recombinant NGF were phenotyped and scored. NGF stimulated generation of neurons, but not neuronal progenitors from embryonic stem cells and affected the proportion of specific types of neurons in cultures of differentiating embryonic stem cells. These findings open vista to employ NGF for generation of specific neuron types from embryonic stem cells for fundamental and toxicological studies.

Fibroblast-like cells as an effective feeder for the cultivation and derivation of new lines of human induced pluripotent stem cells.

Induced pluripotent stem cells (iPSCs) can be a highly informative model of hereditary and sporadic human diseases. In the future, such cells can be used in substitution and regenerative therapy of a wide range of diseases and for the treatment of injuries and burns. The ability of iPSCs derived from patients with Parkinson's disease to differentiate into fibroblast-like cells (derivatives) was studied. It was found that these cells can serve as an effective feeder layer not only to maintain the pluripotency of allogenic and autologous iPSCs but also to derive new iPSC lines.

Investigation of the effect of α-melanocyte-stimulating hormone on proliferation and early stages of differentiation of human induced pluripotent stem cells.

We have studied the influence of α-melanocyte-stimulating hormone (α-MSH) on proliferation and early stages of differentiation of human induced pluripotent stem cells (iPSc). We have demonstrated that α-MSH receptor genes are expressed in undifferentiated iPSc. The expression levels of MCR1, MCR2, and MCR3 increased at the embryoid body (EB) formation stage. The formation of neural progenitors was accompanied by elevation of MCR2, MCR3, and MCR4 expression. α-MSH had no effect on EB generation and iPSc proliferation at concentrations ranging from 1 nM to 10 µM. At the same time, α-MSH increased the generation of neural rosettes in human iPSc cultures more than twice.

Investigation of the effects of GABA receptor agonists in the differentiation of human induced pluripotent stem cells into dopaminergic neurons.

The influence of GABA receptor agonists on the terminal differentiation in vitro of dopaminergic (DA) neurons derived from IPS cells was investigated. GABA-A agonist muscimol induced transient elevation of intracellular Ca2+ level ([Ca2+] i ) in the investigated cells at days 5 to 21 of differentiation. Differentiation of cells in the presence of muscimol reduced tyrosine hydroxylase expression. Thus, the presence of active GABA-A receptors, associated with phenotype determination via Ca2+-signalling was demonstrated in differentiating human DA neurons.

[Clinostatting effects on neuronal differentiation of embryonic stem cells from mice strain R1].

The model of embryonic stem cells from R1 mice at the stage of embryoid bodies was used to study effects of slow clinostatting on neuronal differentiation with the help of two markers--beta-III tubulin (early differentiation) and MAP2 (late differentiation). As compared with the control, the number of beta-III tubulin-positive neurons was found increased and of MAP2-positive neurons--decreased. As regards MAP2- positive neurons, it is concluded that the gravity factors have a specific effect on EB. The beta-III tubulin staining makes possible determination of the total number of neuronal cells at different stages of development. The observed increase in the number of beta-III tubulin-positive neurons may evidence a nonspecific mechanic effect of clinostatting at the EB stage. It was shown that EB cells are particularly sensitive to clinostatting.

[Studies of the primary effects of chronic clinostatting of embryonal mice stem cells in vitro].

Effects of randomized gravity vector (clinostatting) on embryonal stem cells (ESC) of mice were evaluated in vitro with respect to proliferation, proliferative potential, and differentiability. Colony formation remained normal up to hour 72 of clinostatting; however, further exposure led to fusion of the ESC colonies. No reliable shifts in the proliferative activity were found, whereas morphometric analysis showed different dynamics of the ESC colonies size in specific periods of the experiment comparing with the control. Evaluation of the ESC proliferative potential after the experiment revealed a trend upward in the number of colonies when compared with the dynamic and static controls. However, the number of resulted EBs in the control tended upward contrary to EBs formed under the conditions of clinostatting and continuous agitation pointing to the importance of local medium conditioning at the beginning of ESC differentiation.

The action of the tumour promoter, TPA, on mutagenesis induced by different agents (UV light, chemical and viral mutagens).

The present paper deals with effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the frequency of induced mutations to 6-mercaptopurine (6MP) and ouabain resistance in Chinese hamster and mouse cells. UV light, bovine adenovirus 3(BAV-3) and 5-bromodeoxyuridine (BrdU) were used as mutagens. TPA was shown to raise the frequency of gene mutations induced by UV light and BAV-3 but it did not enhance the mutagenic effect of BrdU. We also examined the ability of BAV-3 and BrdU to induce tumours in mice. BrdU was shown to have no carcinogenic effect. The results suggest that TPA enhances the mutagenic effect only for carcinogenic mutagens.

Semi-conservative synthesis of DNA in UV-sensitive mutant cells of Chinese hamster after UV-irradiation.

A study was made of the rate of semi-conservative DNA synthesis in asynchronous UV-resistant (clone V79) and UV-sensitive clones (VII and XII) of Chinese hamster cells after UV-irradiation. In all 3 clones studied, UV-irradiation (5-30 J/m2) induced a decrease in the rate of DNA synthesis during the subsequent 1-2 h. In the resistant clone (V79) recovery of DNA synthesis rate started after the first 2 h post-irradiation (5 J/m2) and by the 3rd hour reached its maximum value, which constituted 70% of that observed in control, non-irradiated cells. The UV-sensitive mutant clones VII and XII showed no recovery in the rate of DNA synthesis during 6-7 h post-irradiation. The results obtained show that the survival of cells is correlated with the ability of DNA synthesis to recover after UV-irradiation in 3 clones studied. The observed recovery of UV-inhibited DNA synthesis in mutant clones may be due to certain defects in DNA repair.

[Analysis of expression of a series of lymphoma-specific genes in human fibroblasts immortalized by SV40 virus]. / Analiz ékspressii riada limfomospetsificheskikh genov v immortalizovannykh virusom SV40 fibroblastakh chelovaka.

Subtraction hybridization was earlier used to obtain cDNA clones corresponding to human genes upregulated in HIV-associated centroblast lymphoma (CL) as compared with HIV-associated immunoblast lymphoma (IL). With inverse subtraction hybridization, clones were isolated that correspond to genes upregulated in IL compared with CL. In addition to cDNAs characterized earlier, the resulting clones contained several (seven CL-specific and three IL-specific) sequences with unknown functions. To identify the lymphoma-specific genes that are overexpressed in early carcinogenesis, Northern blotting was used to assess the level of gene transcription in two human fibroblast lines and in their derivatives immortalized with either a temperature-sensitive mutant of SV-40 or with pSV3neo carrying the SV-40 A gene, considering the latter as a model of early cell malignant transformation. Increased expression in at least one immortalized line compared with normal fibroblasts was observed for set, a-myb, ND1, ND2, ND4 (NADH dehydrogenase subunits 1, 2, and 4), COX2, COX3 (cytochrome-c-oxidase subunits 2 and 3), KIAA0129, and the gene corresponding to cDNA hss2-1-7-10. High expression of these genes was assumed to be associated not only with lymphomogenesis, but also with early transformation (immortalization) of other, nonlymphoid cells. Expression of the calpain gene and the gene corresponding to cDNA hss2-2-9-5 proved to be lower in immortalized than in normal fibroblasts. This was considered indicative of an alternative mechanism of fibroblast transformation or of different processes regulating the expression of these genes in early and late carcinogenesis.

[Isolation and characterization of immortalized human fibroblasts]. / Poluchenie i kharakteristika immortalizovannykh fibroblastov cheloveka.

A clone of immortalized human fibroblasts with an extended life span in culture was obtained after infection with a temperature-sensitive mutant (tsA 239) of SV40. In comparison with the parental cells, the clone exhibited an increase in the efficiency of plating, decreased doubling time, and serum dependence. No anchorage independence was observed. This means that the immortalized cells were not fully malignant, since growth in soft agar is one of the most typical features of malignancy. The PCR analysis has revealed the presence of viral DNA at early (25th) passages after infection and its absence after prolonged culturing (46th passage). These results support the data obtained after studies of T antigen expression by the indirect immunofluorescence method. No reversion to the normal phenotype was observed after transfer of the immortalized cells from the permissive temperature to the temperature restrictive for the virus (33 degrees and 39 degrees C, respectively). We deem it probable that the mutagenic effect of SV40 is realized after the hit-and-run mechanism, hence, its presence is not indispensable for the maintenance of the transformed phenotype.

[Targeting the gene for platelet-derived growth factor A-chain (PDGF-A) and preparation of chimeric mice with a "knockout" genome]. / Targeting gena A-tsepi trombotsitarnogo faktora rosta (PDGF-A) i poluchenie khimernoi myshi s "nokautirovannym" genom.

A vector was selected for homologous recombination to generate mouse embryonic stem cell clones with disrupted platelet-derived growth factor A (PDGF-A) chain gene. A chimeric mouse with targeted PDGF-A gene has been created.

[Induction of gene mutations and the lethal action of ultraviolet rays in synchronized Chinese hamster cells]. / Induktsiia gennykh mutatsii i letal'noe deistvie ul'trafioletovykh luchei v sinkhronizirovannykh kletkakh kitaiskogo khomiachka.

Lethal and mutagenic effects of UV light were studied in two synchronized UV-sensitive Chinese hamster cell clones differing in the degree of sensitivity (CHS1, CHS2). It is shown that the phase of mitosis is most resistant to the lethal effect of UV. The sensitivity of both cell clones increases in the pre-synthetic phase and reaches its maximum during the phase of DNA synthesis. Positive correlation of cell sensitivity to mutagenic and lethal action of UV was observed when studying induced mutability in both cell clones during the phase of DNA synthesis. However, the study of the mutagenic effect of UV on different phases of the synthesis. However, the study of the mutagenic effect of UV on different phases of the cell cycle (M, G1, S) in the less UV-sensitive cell clone has revealed that the maximal mutation yield takes place when cells are irradiated at G1 (CHS1). The discrepancy observed may be due to different probability of the phenotypic detection of pre-mutational lesions, arising at different phases of the cell cycle. It is shown that only one cell generation is necessary for the expression of pre-mutational changes. These data allow to conclude that the increased mutation rate observed at G1 (as compared with S) reveals rather a probability of the expression but not of the occurrence of pre-mutational lesions. It is suggested that the fixation of mutations in the cells studied proceeds during the post-replication repair synthesis.

[Spontaneous mutation rate in clones of Chinese hamster cells differing in UV sensitivity]. / Temp spontannogo mutirovaniia v klonakh kletok kitaiskogo khomiachka, razlichaiushchikhsia po UF-chuvstvitel'nosti.

The paper deals with a study of the rate of spontaneous mutations to 6-mercaptopurine resistance in cells of CHR2, CHS2 clones differing in sensitivity to the lethal and mutagenic effects of UV irradiation. An enhanced UV-sensitivity of CHS2 clone was shown earlier to be the result of a disturbance in postreplication DNA repair. Estimation of spontaneous mutation rate in the HPRT locus demonstrated that it is similar for both clones (1.5 to 1.8 X 10(-5) per cell, per generation). The defect of postreplication DNA repair in Chinese hamster cells was found to be unrelated to the increase in spontaneous mutability. The possible role of the repair process in the mechanism of initiation of spontaneous and induced mutations in Chinese hamster cells with the enhanced UV-sensitivity is discussed.

[Hybridization of Chinese hamster cells sensitive to ultraviolet irradiation]. / Gibridizatsii kletok kitaiskogo khomiachka, chuvstvitel'nykh k ul'trafioletovomu oblucheniiu.

Resistance to UV-light was studied in two UV-sensitive aneuploid Chinese hamster cell clones to different origin and degree of sensitivity, their respective polyploids and somatic cell hybrids. The karyotype of the parental clones, cell hybrids and polyploids was analyzed in parallel. A great variability of karyotypes was detected in hybrid cells. Serial cultivation of hybrids was accompanied by chromosome loss. Soon after fusion the hybrid clones proved to be more resistant to UV than the parental sensitive cells. However, their sensitivity increased with passages. The comparison of UV-sensitivity with data on karyotype analysis allowed to assume that the increase in sensitivity was correlated with the loss of particular chromosomes or chromosome regions. The results obtained indicated the existence of a polygenic control of UV-sensitivity, the multiple genes being assigned to different chromosomes. A reverse effect of ploidy was detected, i.e. a decrease in the resistance to the lethal action of UV-light in polyploids as compared to the parental clones.

[Mutagens and the tumor promoter]. / Mutageny i opukholevyi promotor.

We studied the effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) and saccharin on the frequency of induced mutations of resistance to 6-mercaptopurine and ouabain in Chinese hamster and mouse cells. UV-rays, bovine adenovirus-3 (BAV-3) and 5-bromdeoxyuridine (BrdU) were used as mutagens. In the case of BAV-3 and BrdU, we investigated, apart from the mutagenic effect, the tumor-inducing activity of these mutagens in mice, BrdU proved to have no carcinogenic effect. The data about the influence of TPA on the mutagenic effect of the three different mutagens indicate that TPA increases the frequency of the gene mutations induced by UV-rays and BAV-3. The results of the study of BrdU and TPA combined action revealed the fact that TPA does not increase the mutagenic effect of BrdU. We demonstrated that saccharin also possesses the promoter activity; it increases the mutagenic effect of BAV-3. The results described above lead to the assumption that TPA influence on the mutagenic effect only takes place when carcinogenic mutagens are used.

[Postreplicative DNA repair in UV-sensitive Chinese hamster cell clones]. / Postreplikativnaia reparatsiia DNK v UF-chuvstvitel'nykh klonakh kletok kitaiskogo khomiachka.

The postreplication repair (PRR) of DNA has been studied in UV-irradiated (10 J/m2) and carcinogen (7-bromomethylbenz(alpha)anthracene -- BMBA) treated (1.65-3.3) 10(-6) M Chinese hamster clones with different UV-sensitivity. Ultracentrifugation in alkaline sucrose gradients has been used. Compared to the UV-resistent clone V-79, the UV-sensitive clone CHS2 displayed a lower effectivity of PRR of DNA after both UV-irradiation and carcinogen treatment, by 6 and 10 times, resp. Thus, there is a positive correlation between lethal and mutagenic effects of UV-irradiation and the effectivity of PRR of DNA. The same conclusion is apparently true in the case of carcinogen 7-BMBA treated Chinese hamster cells.

[Immortalization of human fibroblasts using tsA mutant of SV40 and pSV3neo plasmid]. / Immortalizatsiia fibroblastov cheloveka pod vozdeistviem tsA-mutanta SV40 i plazmidy pSV3neo.

Clones of immortalized human fibroblasts with an extended life span in culture and a capability of subloning were obtained after the infection with a temperature sensitive mutant (tsA 239) of SV40 virus and pSV3neo plasmid. As compared with the parental cells, the obtained clones exhibited increased plating efficiency, decreased doubling time, and serum dependence. We did not obtained the colony formation during cultivation of immortalized cells in semiliquid agar. This means that our cells were not completely malignant. The PCR (polymerase chain reaction)-analysis has revealed the presence of viral DNA at early passages (25th passage) after the infection by tsA SV40, and its absence after a prolonged cultivation (46th passage). PCR-analysis of the clones obtained after pSV3neo transfection has revealed the presence of gene A sequences either at early (9-15), or later (62) passages. The expression of the gene A product in cells of these clones was revealed only early passages (11 and 35). Possible mechanisms of immortal phenotype origin in human diploid cells after the action of ts-mutant and other constructions of SV40 are discussed.