C. elegans dosage compensation: a window into mechanisms of domain-scale gene regulation.

The C. elegans dosage compensation complex (DCC) reduces transcript levels from each of the two hermaphrodite X chromosomes to equalize X-linked gene expression to that of XO males. Several of the proteins that comprise the DCC are homologous to subunits of the evolutionarily conserved condensin complexes, which in most organisms function in mitotic and meiotic chromosome condensation. These include the DCC subunits MIX-1 and DPY-27, which belong to the structural maintenance of chromosomes (SMC) family of proteins. Several of the C. elegans DCC subunits also perform double duty as members of the canonical meiotic and mitotic condensin complexes. Here, we review what is known about the C. elegans DCC and how study of this model might shed light on general mechanisms of domain-scale transcriptional regulation. We discuss how condensin-like complexes may be targeted to specific chromosomal locations for performance of their functions.