The organization of DNA or chromatin fibers in the eukaryotic cell nucleus is dynamically regulated. Sub-regions of chromatin with different transcriptional activities are organized into domains with various degrees of compactness. Previous studies identified a class of transcriptional regulators called chromatin insulators or boundary elements". They function as transcriptional barriers in the genome. Accumulating evidence suggests that chromatin insulators are important players in the organization of the chromatin structure. This project will investigate the molecular mechanism through which a chromatin insulator functions in the cell nucleus. The focus of this project is on a chromatin insulator of Drosophila melanogaster called gypsy which is the most understood insulator to date. The gypsy insulator is a DNA sequence containing 12 copies of the binding site for a DNA-binding protein named Suppressor of Hairy-wing [Su(Hw)] which recruits other insulator proteins to organize the insulator complex. It has been reported that the centrosomal protein CP190 is an essential component of the gypsy insulator. CP190 is the only known insulator protein that is present in the centrosome during mitosis. During interphase, CP190 physically associates with the Su(Hw)-mediated complex at the gypsy locations on the chromatin. In addition, CP190 defines a distinct chromatin-associated complex which lacks Su(Hw). Preliminary evidence suggests that the two types of CP190 complexes interact to organize endogenous insulators. The research in this project will define the role of each CP190's functional domain on CP190's chromatin insulator function and will investigate the possible functional relationship between the two types of CP190-containing insulators.
BROADER IMPACT: This project investigates a fundamental question concerning the gene regulation in the eukaryotic cells. The observations will provide insights into the molecular mechanisms through which chromatin insulators regulate gene expression and more generally, chromatin structure and organization of the cell nucleus. This project provides interdisciplinary research training in the fields of Genetics and Cell Biology to graduate students and undergraduate students. Particular efforts will be made to recruit candidates from underrepresented minority groups for these positions. The rationale and the results of this project will communicated to the public via an open website and through internship research programs for undergraduate and high school students. The results of the study will be presented at national meetings and will be published in peer-reviewed scientific journals. These publications and presentations will foster interdisciplinary exchange between Cell Biology and Genetics societies.
