Roles of Chromatin Remodeling Factors Fun30 and Isw1 in Heterochromatin

University Of Rochester, Rochester NY

Investigators

Abstract

Intellectual Merit: Eukaryotic DNA is packaged into chromatin via the formation of nucleosomes, structures in which about 147 base pairs of DNA are wrapped around histone proteins. The genome can be divided into condensed chromatin domains termed heterochromatin and decondensed domains referred to as euchromatin. Heterochromatin plays key roles in genome integrity and in regulation of gene expression, and it is composed of highly ordered nucleosomes with characteristic histone modifications that are recognized by heterochromatin-binding proteins. Heterochromatin is generally refractory to gene expression. Despite extensive studies, exactly how the primary and higher order structures of heterochromatin are formed and maintained is not resolved. Chromatin remodeling factors have the ability to change the structure, dynamics and positioning of nucleosomes in chromatin, and they are linked to heterochromatin formation and maintenance in organisms ranging from yeast to humans, but how they contribute to heterochromatin structure is unclear. Heterochromatin in the highly tractable yeast Saccharomyces cerevisiae has long served as a paradigm for heterochromatin studies. This system will be used to examine the mechanisms of function of two chromatin-remodeling factors, Fun30 and Isw1, in the formation and maintenance of heterochromatin. The investigator will test the model that Fun30 is important for formation of mature heterochromatin during the de novo establishment of heterochromatin and investigate the potential role of Fun30 in the restoration of heterochromatin following its disruption by DNA replication. The investigator will also examine how Fun30 is selectively recruited to heterochromatin and how its function is regulated. Isw1, unlike Fun30, is not required for the formation of heterochromatin structure, but plays a critical role in maintaining the stability of heterochromatin. The investigator will test if Isw1 contributes to the stability of heterochromatin by assisting the formation of a high order heterochromatin structure, regulating the dynamics of heterochromatin, and/or strengthening nucleosome structure. The investigator will also examine how the functional domains of Isw1 contribute to heterochromatin. Results from this project should provide new insights into the roles of Fun30 and Isw1 in the formation, inheritance and maintenance of heterochromatin, and shed light on the functions of chromatin remodelers in heterochromatin in higher organisms including humans. Broader impact: This project is expected to enhance the investigator's teaching and allow him to continue to provide undergraduate and high school students with opportunities to participate in biological research as well as to maintain his interactions with faculty and students at undergraduate colleges. The project would enhance the investigator's role as the instructor for the primary literature-based upper level course Eukaryotic Gene Regulation. Both heterochromatin and chromatin remodelers are covered in this course. New insights into the roles of chromatin remodelers in heterochromatin gained from the research will be incorporated into class discussions. The investigator has a strong record and extensive experience in mentoring undergraduate students in research, including women and members of underrepresented groups. In the past ten years, 22 undergraduate students including 9 female and 2 underrepresented minority students have studied in the investigator's lab. These students gained knowledge and research experiences and became more fascinated with biological sciences. Moreover, a high school student did a senior summer project in the investigator's lab, and as a result became excited about experimental biology. The research will allow the investigator to continue to provide such opportunities for undergraduate as well as graduate students, and to allow students to gain research experience in molecular biology, genetics and biochemistry and contribute to studies of the roles of chromatin remodelers. The investigator will also continue to provide high school students opportunities to do senior projects or summer internships. The investigator will present results from the project at conferences or academic institutions. They investigator will continue to interact with faculty and students at undergraduate colleges by meeting with them and presenting seminars. The investigator will also provide opportunities for faculty at undergraduate colleges to spend their sabbaticals to do research in his lab.