Condensin function in dosage compensation.

Dosage compensation is an essential process that equalizes X-linked gene dosage between the sexes. In the worm Caenorhabditis elegans, a complex of proteins called the dosage compensation complex (DCC) binds both X chromosomes in hermaphrodites to downregulate gene expression two-fold and hence to reduce X-linked gene expression levels equal to that in males. Five subunits of the DCC form the condensin I(DC) complex, a homolog of the evolutionarily conserved condensin complex required for chromosome segregation and compaction during mitosis and meiosis. How related complexes can perform such diverse functions remains a mystery. Nevertheless, it is believed that the mitotic and interphase functions of condensin are mechanistically related and understanding one process will reveal new insights into the other. We discuss how during worm dosage compensation a condensin-mediated function may guide the organization of the interphase chromatin fibers, leading to the formation of a repressive nuclear compartment.