What is the Origin of ESC/E(Z) Complex?

The nomenclature is based on the names of its core components in Drosophila: Extra Sex Combs (ESC) and Enhancer of Zeste (E(Z)). The complex belongs to the Polycomb Group (PcG) of proteins, which were initially identified through their role in repressing homeotic gene expression in fruit flies.

What is the Mechanism of ESC/E(Z) Complex?

The core enzymatic function resides in the E(Z) component, which is a histone methyltransferase. This enzyme catalyzes the trimethylation of lysine 27 on histone H3 (H3K27me3). The resulting methylation mark acts as a docking site for other repressive proteins, leading to chromatin compaction and transcriptional silencing of target genes. In human cells, the homologous complex is PRC2, and its dysregulation can lead to aberrant silencing of tumor suppressor genes or inappropriate activation of developmental pathways, potentially contributing to endocrine-related malignancies.

ESC/E(Z) Complex

Meaning

The ESC/E(Z) Complex is a crucial multi-protein assembly that functions as a Polycomb Repressive Complex 2 (PRC2) in Drosophila, an important model organism for genetics and development. This complex is a key epigenetic regulator, primarily responsible for establishing and maintaining repressive chromatin states through the methylation of histone proteins. Its function is to silence gene expression, playing a vital role in cellular differentiation, embryonic development, and maintaining cell identity, which has implications for endocrine cell fate and cancer biology.