CAREER: Runx-mediated Silencing of CD4 Transcription

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

To address the research goals of this project, Dr. Telfer's laboratory will study how the protein Runx3 regulates expression of an important gene in T cells called CD4. The CD4 gene encodes a protein on the surface of T cells that helps determine their function. Runx3 binds to the DNA containing the CD4 gene during T cell development, and in some of the developing T cells, catalyzes the permanent silencing of CD4 expression. This silencing is inherited; persisting even after the cell divides multiple times as a long-lived mature T cell in the blood. Since this gene silencing is so persistent, it is probable that it is the result of a Runx3-mediated modification of the DNA-associated proteins known as histones. All of the DNA in a cell is wrapped around multiple groups of histones, like a long thread on many spools, in order to package the DNA compactly enough to fit into the nucleus. Modification of histones is known to regulate the expression of genes by regulating how loosely or tightly the DNA is packaged. Genes located in tightly packaged DNA are not expressed and this tightness of packaging and resulting silencing of genes is inherited by the daughter cells. Dr. Telfer's laboratory will investigate whether Runx3 silences CD4 expression in immature T cells by attracting histone-modifying enzymes to the DNA containing the CD4 gene. These enzymes could then modify the histones so that the DNA containing the CD4 gene would be packaged more tightly and expression of CD4 silenced. Introducing mutated or normal forms of Runx3 into primary immature T cells and examining their effects on proteins such as histones associated with the CD4 gene will test this hypothesis. Understanding how permanent gene silencing is mediated is very important for understanding processes in cells such as stem cell self-renewal and differentiation. The research and educational goals of this project are highly integrated with the educational goals of the Department of Veterinary and Animal Science and the Institute for Cellular Engineering (ICE) at the University of Massachusetts Amherst. ICE represents a research and educational collaboration between biologists pursuing questions regarding the mechanisms of stem cell differentiation into specific cells and engineers developing processes to produce stem cells or differentiated cells reliably and in bulk. In this context, Dr. Telfer will improve the teaching of undergraduates in an introductory cellular and molecular biology course through the implementation of methods designed to encourage active learning by the students and rapid assessment of the student's knowledge acquisition by the teacher. These new methods represent a paradigm shift from the traditional teaching method of lecture and exams. The aim of active learning and rapid student assessment is to teach deep learning techniques, which are critical to the retention of a knowledge base. The success of these methods will be assessed by midterm and end-of-semester student evaluation forms as well as by interviews with faculty members teaching the same students in subsequent years. The retention in science of female and minority students will be improved through more effective teaching and by encouraging undergraduate and graduate research experiences in this research project and other related research projects under the collaborative umbrella of ICE at the University of Massachusetts Amherst.