The chromatin of an organism is composed of a variety of functional domains that are programmed by a group of determinants that range from trans-acting factors and histone modifications. The long-term goal of the chromatin field is the identification of these determinants and the understanding of how these determinants program the establishment of a chromatin domain. One such domain is found within the promoters of genes in the form of a functionally significant nucleosome-free region (NFR) that is flanked by two nucleosomes carrying the histone H2A variant H2A.Z. These NFRs have been observed in both budding yeast and human cells. There are two unresolved questions that this proposal will address. First, what is the mechanism of NFR formation, and second, how is H2A.Z specifically deposited into the two nucleosomes that flank a NFR? This research will be directed by the discovery of a DNA signal called Reb1:dT7 that is sufficient to form a NFR flanked by H2A.Z at a locus that normally has no such chromatin architecture. A testable model for NFR formation by this particular DNA signal was developed, and this model will be generalized to endogenous promoters. Furthermore, H2A.Z deposition is not a prerequisite for NFR formation, which suggests that H2A.Z deposition is directed to regions of chromatin that have an established NFR. An understanding of how H2A.Z deposition is targeted will represent a significant contribution to the chromatin field especially because this histone variant is conserved in nearly all metazoans, including humans. A wide variety of diseases including cancers are caused by misregulation of genes, and this research is focused on the general establishment of the structure of promoters, which regulate genes. This research uses budding yeast, which have promoter structures that are very similar to that found in human cells. Yeast is an experimentally tractable organism that can be used in a variety of experiments that cannot be done with human cells, which enables us to dissect molecular mechanisms and then extrapolate our findings to human cells.
| Garcia, Jennifer F; Dumesic, Phillip A; Hartley, Paul D et al. (2010) Combinatorial, site-specific requirement for heterochromatic silencing factors in the elimination of nucleosome-free regions. Genes Dev 24:1758-71 |
| Hartley, Paul D; Madhani, Hiten D (2009) Mechanisms that specify promoter nucleosome location and identity. Cell 137:445-58 |
