Molecular mechanisms of the Polycomblike family proteins in epigenetic regulation and their biological functions

Abstract

<p indent="0mm">The PRC2 complex is a major complex in the Polycomb group of proteins. It plays an essential role in cell proliferation, differentiation, and the maintenance of cellular identity. PRC2 functions in gene repression mainly by modifying chromatin and regulating chromatin structure, among which the tri-methylation mark on histone H3 at Lys27 (H3K27me3) added by EZH2, the core PRC2 component, is a hallmark of gene repression. PRC2 core components must bind PRC2-associated proteins to form a holo-enzyme and become fully active. PRC2-associated proteins, such as Polycomblike (PCL) proteins, are important in regulating the function of PRC2. Recent studies have revealed that human PCL proteins play key roles in regulating the activity and the recruitment of chromatin by PRC2. In addition, PCL proteins are closely related to several human cancers. Thus, advances in the structure and function of PCL proteins would facilitate our understanding of their roles in PRC2 regulation and would expedite the development of strategies for therapeutically targeting PCL-related cancers. In this review, we summarize recent progress on the structure and function of PCL proteins, with an emphasis on the molecular mechanisms and biological functions of human PCL proteins.