Molecular basis of transvection

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DESCRIPTION (provided by applicant): Our laboratory is interested in understanding the mechanisms presiding enhancer-promoter interactions and the role of insulators in gene expression regulation. The goal of this proposal is to explore the molecular mechanisms underlying the phenomenon of transvection. Interaction of enhancers with promoters is a critical step in the orchestrated process leading to time and tissue specific regulation of gene expression. Enhancers can specifically activate promoters even at distances longer than 100 kb. Remarkably, enhancers can also trans-activate promoters located in homologue chromosomes, a phenomenon known as transvection. Transvection depends on somatic pairing between chromosomes, wherein the expression of one gene is influenced by regulatory signals emerging from its corresponding allele on the homologue chromosome. Transvection has been very well characterized at the genetic level in Drosophila, but numerous examples reported from multiple organisms including yeasts, plants and mammals, suggest that trans-activation (i.e. transvection) is a conserved eukaryotic regulatory feature. We propose that insulators are the molecular vehicles by which enhancers can communicate with promoters located in separate chromosomes. The following two aims are designed to test this hypothesis. A: assess the ability of gypsy insulators to mediate transvection using transgenic assays. Cell and molecular biology assays as well as mutational analysis will asses the involvement of insulators in experimentally controlled transvection settings. B: assess whether there is a general role of endogenous insulators in transvection. We will map and characterize specific endogenous insulators with a predicted role in transvection using computer analysis, fluorescence microscopy, gel shift assays and transgenic assays. Genetic analysis will also assess the role that insulator proteins play in previously reported transvection phenomena. These studies might have an immediate repercussion in the general understanding of the regulatory processes involved in somatic and germ-line development. Both, transvection as well as genome insulators may be involved in the control of transcription of numerous genes and therefore have a broad impact in the biology of human diseases, including cancer. Understanding how enhancers interact with promoters and the role of insulators in this process may provide new avenues to approach the study of genetic diseases.