Section on Gene Expression
Judy Kassis, Section Head
During development and differentiation, genes either become competent to be expressed or are stably silenced in an epigenetically heritable manner. This selective activation/repression of genes leads to differentiation of tissue types. Recent evidence suggests that modifications of histones in chromatin contribute substantially to determining whether a gene will or will not be expressed. Our group is interested in understanding how chromatin-modifying protein complexes are recruited to the DNA. In Drosophila, two groups of genes, the Polycomb group (PcG) and the Trithorax group (TrxG), are important for inheritance of the silenced and active chromatin state, respectively. Regulatory elements called Polycomb group response elements (PREs) are cis-acting sequences required for the recruitment of chromatin-modifying PcG protein complexes. Recently, it has been suggested that TrxG proteins act through either the same or overlapping cis-acting sequences. Our group is working on understanding how PcG and TrxG proteins are recruited to the DNA.