Adequate biological models are a prerequisite to screening and development of probiotic drugs. In the present study, Caco-2 cell line is reviewed as a model for analyzing properties of probiotics. This cell culture possesses all the characteristics necessary for evaluating the effects of probiotic drugs on a wide range of both intracellular processes and intercellular interactions. Informativeness of Caco-2 cells is in the focus of the present review.

The phenotypic manifestations of increased expression of the Bap170 and e(y)3 (SAYP) genes in D. melanogaster were analyzed. Using the wing disc model, we show that moderate co-expression of Bap170 and e(y)3 genes in wing discs leads to abnormalities in wing veining. which was probably caused by suppression of EGFR/Ras/MAPK signaling pathways. Strong induction of co-expression of the above genes in wing discs leads to complete suppression of wing development in adults. Ubiquitous co-expression of Bap170 and e(y)3 is lethal at the 1st instar larval stage and leads to the formation of melanotic tumors. The above phenotypes are observed exclusively when Bap170 and e(y)3 are co-expressed. This evidence suggests a robust synergistic effect of the combined action of these genes, which is manifested in the hyperactivity of cell proliferation and differentiation.

SAYP and Bap170, subunits of the SWI/SNF remodeling complex, have the ability to support enhancer-dependent transcription when artificially recruited to the promoter on a transgene. We found that the phenomenon critically depends on two subunits of the Mediator kinase module, Med12 and Med13 but does not require the two other subunits of the module (Cdk8 and CycC) or other subunits of the core part of the complex. A cooperation of the above proteins in active transcription was also observed at endogenous loci, but the contribution of the subunits to the activity of a particular gene differed in different loci. The factors SAYP/Bap170 and Med12/Med13 did not form sufficiently stable interactions in the extract, and their cooperation was apparently local at regulatory elements, the presence of SAYP and Bap170 in a locus being necessary for stable recruitment of Med12 and Med13 to the locus. In addition to the above factors, the Nelf-A protein was found to participate in the process. The cooperation of the factors, independent of enzymatic activities of the complexes they are part of, appears to be a novel mechanism that maintains promoter activity and may be used in many loci of the genome. Extended intrinsically disordered regions of the factors were assumed to sustain the mechanism.

The Bap170 subunit of the SWI/SNF chromatin remodeler exhibits activator functions when artificially recruited to the LacZ reporter promoter in enhancer-dependent transcription. In this study, the functional significance of Bap170 protein domains in reporter activation was analyzed. Deletion of the ARID domain does not reduce Bap170 activity. Increased expression of the LacZ reporter was observed in the form of Bap170 without a region that includes LXXLL motifs. Deletions of the central (RFX domain and IDRs) and C-terminal region (zinc fingers) of Bap170 lead to a significant decrease in transgene expression. Apparently, these regions of Bap170 are critical for the function of this protein in enhancer-dependent transcription.