[Intracellular localization of transcription factor PROX1 in the human retina in ontogeny].

The spatiotemporal intracellular localization of the transcription factor PROX1 in the human retina during prenatal development (fetal weeks 9.5 to 31) and in the adult human retina was studied for the first time. The PROX1 protein was identified in the cell nuclei of the neuroblast retinal layers at the stage of active cell proliferation (fetal week 9.5) as well as in the nuclei of differentiating neurons of the inner nuclear retinal layer (horizontal, amacrine, and bipolar cells) from weeks 13 to 31 of prenatal development. The PROX1 protein localization in the adult retina was the same as at the late stage of prenatal development. Our results indicate the involvement of the transcription factor PROX1 in the regulation of proliferation of progenitor cells and differentiation of the inner nuclear layer cells of the human retina. These results confirm the conservative functions of Prox1/PROX1 in the vertebrate retina.

[FGF2 signaling pathway components in tissues of the posterior eye sector in the adult newt Pleurodeles waltl].

The FGF2 signaling pathway components in tissues of the posterior wall in the normal and regenerating eye of the adult Pleurodeles waltl newt were detected for the first time. The fgf2 gene expression was found in the retina, retinal pigment epithelium, and choroid using polymerase chain reaction (PCR). A high homology of the mRNA nucleotide sequence of the most conservative fgf2 gene region in the P. waltl with the fgf2 orthologs in other vertebrates was proved. The Fgf2 protein aminoacid sequence of the P. waltl newt demonstrates even more homology with this growth factor in other vertebrates. The Fgf2 protein with a molecular weight 35 kDa was found in the studied eye tissues using Western blot hybridization. Localization of the Fgf2 protein and its Fgfr receptors was immunohistochemically studied in the pigment epithelium, choroid, central and growth retina regions of the newt native eye, and in the connective cilium of photoreceptors. Using real-time PCR and immunohistochemistry methods, it was found that the fgf2 gene down-regulation and a decrease in the intensity of the immunochemical reaction of its protein product (Fgf2) occur in the early period after the retina removal (in 4-8 days) (as compared with those in the same department of the unoperated eye).

[Analysis of TGFbeta2 expression in human eye tissues in prenatal development].

In this work we focus on the temporal and spatial characteristics of TGFbeta2 expression in various human eye tissues during prenatal development from fetal weeks 8 to 22. We used the complex approach: the analysis of TGFbeta2 gene expression by PCR and the localization of TGFbeta2 protein by immunohistochemistry. TGFbeta2 was detected in all eye tissues. Our results suggest that differential expression pattern of TGFbeta2 in the lens and retina is correlated with the cell type and differentiation state. The data obtained give evidence to the TGFbeta2 contribution to forming of eye tissues of various embryonic origins.

[Transcriptional factor Pitx2: localization during triton retina regeneration].

For the first time immune-chemical analysis of transcriptional factor Pitx2 localization during triton retina regeneration after its removal and also in tissues of a nonoperated eye of an adult triton has been carried out. Protein Pitx2 has been found in the nucleus of the earliest neuroblasts that form the germ of the retina. At a later stage of retina regeneration, Pitx2 was found in the nucleus of differentiating cells of ganglionic layers that correspond to Pitx2 protein localization in the native retina. Protein Ptix2 has also been found in the nucleus of less differentiated cells of the peripheral region of regenerative and native retina. It was demonstrated that protein Pitx2 is expressed not only in retina but also in other tissues of the posterior sector of the eye (pigment epithelium, choroid) using immune-histochemical and Western blot hybridization. It is supposed that transcriptional factor Pitx2 has been involved in the control of subsequent stages of retina regeneration from pigment epithelium cells.

[Activation of reconstructive processes in rat tissues under the action of radiofrequency current with a periodic impulse mode of modulation].

The action of a current in the radio frequency range with a periodic impulse mode of modulation on the activation of recovery processes in the skin and skeletal muscles has been studied. The action of a radio frequency current with a power of 1 W, as opposed to that of the weaker action (0.1 W) and stronger (4 W) action, leads to the activation of recovery processes in the skin and skeletal muscles. Recovery processes are manifested in the increase in proliferation and activation of angiogenesis in the skin, and also in formation of new muscle fibers. Recovery processes in muscles are accompanied by activation and migration of satellite cells of muscle tissue in the zone of action of the radio frequency current.

[Expression of regulatory genes Pax6, Otx2, Six3, and FGF2 during newt retina regeneration].

Molecular-genetic mechanisms of regeneration of adult newt (Pleurodeles waltl) retina were studied. For the first time, a comparative analysis of the expression of regulatory genes Pax6, Otx2, and Six3 and Fgf2 genes encoding signal molecules was performed in the native retinal pigment epithelium (RPE) and retina and at successive stages of retina regeneration. Cell differentiation types were determined using genetic markers of cell differentiation in the RPE (RPE65) and the retina (betaII-tubulin and Rho). Activation of the expression of neurospecific genes Pax6 and Six3 and the growth factor gene Fgf2 and suppression of activation of the regulatory gene Otx2 and the RPE65 were observed at the stage of multipotent neuroblast formation in the regenerating retina. The expression of genes Pax6, Six3, and Fgf2 was retained at a later stage of retina regeneration at which the expression of retinal differentiation markers, the genes encoding betaII-tubulin (betaII-tubulin) and rhodopsin (Rho), was also detected. We assume that the above regulatory genes are multifunctional and control not only transdifferentiation of RPE cells (the key stage of retina regeneration) but also differentiation of regenerating retina cells. The results of this study, demonstrating coexpression of Pax6, Six3, Fgf2, betaII-tubulin, and Rho genes, provide indirect evidence for the interaction of regulatory and specific genes during retina regeneration.

[Analysis of the expression pattern of regulatory genes Pax6, Prox1, and Six3 during regeneration of eye structures in the newt]. / Issledovanie patterna ékspressii reguliatornykh genov Pax6, Prox1 i Six3 v khode regeneratsii struktur glaza tritona.

We studied tissue-specific expression of homeobox genes Pax6, Prox1, and Six3 during regeneration of the retina and lens. In the native retina, mRNA of Pax6, Prox1, and Six3 was predominantly localized in ganglion cells and in the inner nuclear layer of the retina. Active Pax6, Prox1, and Six3 expression was detected at early stages of regeneration in all proliferating neuroblasts forming the retinal primordium. Low levels of Pax6, Prox1, and Six3 mRNA were revealed in depigmented cells of the pigment epithelium as compared to the proliferating neuroblasts. At the intermediate stage of retinal regeneration, the distribution of Pax6, Prox1, and Six3 mRNA was diffuse and even all over the primordium. During differentiation of the cellular layers in the course of retinal regeneration, Pax6, Prox1, and Six3 mRNA was predominantly localized in ganglion cells and in the inner part of the inner nuclear layer, which was similar to the native retina. An increased expression was revealed in the peripheral regenerated retina where multipotent cells were localized. The dual role of regulatory genes Pax6, Prox1, and Six3 during regeneration of eye structures has been revealed; these genes controlled cell proliferation and subsequent differentiation of ganglion, amacrine, and horizontal cells. High hybridization signal of all studied genes was revealed in actively proliferating epithelial cells of the native and regenerating lens, while the corneal epithelium demonstrated a lower signal. Pax6 and Prox1 expression was also revealed in single choroid cells of the regenerating eye.

[An analysis of the expression of the genes containing the LeR-1 and VeR-1 sequences in the embryogenesis, regeneration and in the intact tissues of newts]. / Analiz ékspressii genov, soderzhashchikh posledovatel'nosti LeR-1 i VeR-1 v émbriogeneze, pri regeneratsii i v intaktnykh tkaniakh u tritonov.

A method of construction of amplified cDNA libraries was developed on the basis of selective inhibition of cDNA amplification and modified for the studied models for analysis of expression of the genes containing LeR-1 and VeR-1 sequences. Time-related changes in expression of these genes were studied during regeneration of the adult lens and during embryogenesis of newts. The pattern of expression of the LeR-1 and VeR-1 genes proved to be not tissue-specific. A fragment adjoining 5'-area of the LeR-1 gene was obtained using a new approach: rapid amplification of cDNA ends by polymerase chain reaction (5'-RACE-PCR). Analysis of the LeR-1 clone primary structure using Gene Bank did not show essential homology with the known nucleotide sequences. Sequence LeR-1 is characterized by evolutionary conservation of genomic DNA in Pleurodeles waltlii, Xenopus laevis, and Rana temporaria.

[Identification of new genes and analysis of their expression during lens and retinal regeneration in adult newts]. / Identifikatsiia novykh genov i analiz ikh ékspressii v protsessse regeneratsii khrustalika i setchatki u vzroslykh tritonov.

During lens regeneration in Pleurodeles waltl, the dorsal iris zone is the cell source of the lens regeneration, while the ventral iris zone can serve as the cells' source of lens regeneration only under certain experimental conditions. The method of subtractive hybridization was used for the identification of genes responsible for the different proliferative potential of these zones. Differential screening of the enriched cDNA libraries, which were obtained as a result of subtractive hybridization of the cDNA samples of the ventral and dorsal iris zones 14 days after lens removal, revealed four clones specific to the dorsal iris and six clones specific to the ventral iris. Two of these, LeR-1 and VeR-1, were structurally characterized. Comparison of their primary structure with data from the Gene Bank showed no essential homology with the known sequences. Time-related changes in LeR-1 and VeR-1 expression were shown during lens regeneration. LeR-1 and VeR-1 expression was activated at the early stages of lens regeneration. The peaks of LeR-1 and VeR-1 expression were observed on the 14th day of lens regeneration in the dorsal and ventral iris zones, respectively. Furthermore, LeR-1 is activated during retina regeneration. The results of Southern hybridization suggest the presence of sequences complementary to LeR-1 in the genomes of Pleurodeles waltl and Rana temporaria. We propose that the activation of LeR-1 expression is related to the triggering of lens regeneration, while the activation of VeR-1 expression accompanies the inhibition of proliferative activity in the ventral iris zone.

[Molecular-biological approaches to studying gene expression during regeneration]. / Molkeuliarno-biologicheskie podkhody v issledovanii ékspressii genov v protsesse regeneratsii.

This paper constitutes a review of the methodical approaches allowing analysis of the mechanisms underlying development and differentiation. Progress in investigation of the mechanisms underlying embryogenesis is related to the discovery of genic families in the Drosophila genome, which are responsible for different periods of embryogenesis. The true revolution in studies of developmental mechanisms began with the application of molecular-genetic methods for analysis of Drosophila mutant lines. The clarification and analysis of the genes controlling regeneration is one of the most effective paths toward an understanding of the mechanisms underlying regeneration. No mutations affecting regeneration are, and the development of alternative (i.e., not based on mutation analysis) methods of discovery of the genes controlling regeneration is necessary for investigation of the genetic mechanisms of regeneration. The advantages and drawbacks of the two main approaches for discovery of the genes controlling regeneration are considered. The first approach is based on the production of a bank of sequences expressed in the regenerating structures and subsequent screening of the bank by the known probes. This approach also involves analysis of the structure, function, and expression pattern of the obtained homologs. The second approach is based on subtractive hybridization, which allows identification of the genes specifically expressed in the regenerating structures. This approach was made it possible to identify, for the first time, new genes specifically expressed during lens and retina regeneration in amphibians.