Sergej B. Akopov

D.Sc (biological sciences)

Leading research fellow (Laboratory of human genes structure and functions)

Phone: +7 (495) 330-70-29


Selected publications

  1. Britanova O., de Juan Romero C., Cheung A., Kwan K.Y., Schwark M., Gyorgy A., Vogel T., Akopov S., Mitkovski M., Agoston D., Sestan N., Molnár Z., Tarabykin V. (2008). Satb2 is a postmitotic determinant for upper-layer neuron specification in the neocortex. Neuron 57 (3), 378–92 [+]

    Pyramidal neurons of the neocortex can be subdivided into two major groups: deep- (DL) and upper-layer (UL) neurons. Here we report that the expression of the AT-rich DNA-binding protein Satb2 defines two subclasses of UL neurons: UL1 (Satb2 positive) and UL2 (Satb2 negative). In the absence of Satb2, UL1 neurons lose their identity and activate DL- and UL2-specific genetic programs. UL1 neurons in Satb2 mutants fail to migrate to superficial layers and do not contribute to the corpus callosum but to the corticospinal tract, which is normally populated by DL axons. Ctip2, a gene required for the formation of the corticospinal tract, is ectopically expressed in all UL1 neurons in the absence of Satb2. Satb2 protein interacts with the Ctip2 genomic region and controls chromatin remodeling at this locus. Satb2 therefore is required for the initiation of the UL1-specific genetic program and for the inactivation of DL- and UL2-specific genes.

  2. Chernov I.P., Timchenko K.A., Akopov S.B., Nikolaev L.G., Sverdlov E.D. (2007). Identification of tissue-specific DNA-protein binding sites by means of two-dimensional electrophoretic mobility shift assay display. Anal. Biochem. 364 (1), 60–6 [+]

    We developed a technique of differential electrophoretic mobility shift assay (EMSA) display allowing identification of tissue-specific protein-binding sites within long genomic sequences. Using this approach, we identified 10 cell type-specific protein-binding sites (protein target sites [PTSs]) within a 137-kb human chromosome 19 region. In general, tissue-specific binding of proteins from different nuclear extracts by individual PTSs did not follow the all-or-nothing principle. Most often, PTS-protein complexes were formed in all cases, but they were different for different nuclear extracts used.

  3. Akopov S.B., Ruda V.M., Batrak V.V., Vetchinova A.S., Chernov I.P., Nikolaev L.G., Bode J., Sverdlov E.D. (2006). Identification, genome mapping, and CTCF binding of potential insulators within the FXYD5-COX7A1 locus of human chromosome 19q13.12. Mamm. Genome 17 (10), 1042–9 [+]

    Identification of insulators is one of the most difficult problems in functional mapping of genomes. For this reason, up to now only a few insulators have been described. In this article we suggest an approach that allows direct isolation of insulators by a simple positive-negative selection based on blocking enhancer effects by insulators. The approach allows selection of fragments capable of blocking enhancers from mixtures of genomic fragments prepared from up to 1-Mb genomic regions. Using this approach, a 1-Mb human genome locus was analyzed and eight potential insulators were selected. Five of the eight sequences were positioned in intergenic regions and two were within introns. The genes of the alpha-polypeptide H+/K+ exchanging ATPase (ATP4A) and amyloid beta (A4) precursor-like protein 1 (APLP1) within the locus studied were found to be flanked by insulators on both sides. Both genes are characterized by distinct tissue-specific expression that differs from the tissue specificity of the surrounding genes. The data obtained are consistent with the conception that insulators subdivide genomic DNA into loop domains that comprise genes characterized by similar expression profiles. Using chromatin immunoprecipitation assay, we demonstrated also that at least six of the putative insulators revealed in this work could bind the CTCF transcription factor in vivo. We believe that the proposed approach could be a useful instrument for functional analysis of genomes.

  4. Vetchinova A.S., Akopov S.B., Chernov I.P., Nikolaev L.G., Sverdlov E.D. (2006). Two-dimensional electrophoretic mobility shift assay: identification and mapping of transcription factor CTCF target sequences within an FXYD5-COX7A1 region of human chromosome 19. Anal. Biochem. 354 (1), 85–93 [+]

    An approach for fast identification and mapping of transcription factor binding sites within long genomic sequences is proposed. Using this approach, 10 CCCTC-binding factor (CTCF) binding sites were identified within a 1-Mb FXYD5-COX7A1 human chromosome 19 region. In vivo binding of CTCF to these sites was verified by chromatin immunoprecipitation assay. CTCF binding sites were mapped within gene introns and intergenic regions, and some of them contained Alu-like repeated elements.

  5. Chernov I.P., Akopov S.B., Nikolaev L.G., Sverdlov E.D. (2006). Identification and mapping of DNA binding proteins target sequences in long genomic regions by two-dimensional EMSA. BioTechniques 41 (1), 91–6 [+]

    Specific binding of nuclear proteins, in particular transcription factors, to target DNA sequences is a major mechanism of genome functioning and gene expression regulation in eukaryotes. Therefore, identification and mapping specific protein target sites (PTS) is necessary for understanding genomic regulation. Here we used a novel two-dimensional electrophoretic mobility shift assay (2D-EMSA) procedure for identification and mapping of 52 PTS within a 563-kb human genome region located between the FXYD5 and TZFP genes. The PTS occurred with approximately equal frequency within unique and repetitive genomic regions. PTS belonging to unique sequences tended to group together within gene introns and close to their 5' and 3' ends, whereas PTS located within repeats were evenly distributed between transcribed and intragenic regions.