HIRA, a mammalian homologue of Saccharomyces cerevisiae transcriptional co-repressors, interacts with Pax3

HIRA maps to the DiGeorge/velocardiofacial syndrome critical region (DGCR) at 22q11 (refs 1,2) and encodes a WD40 repeat protein similar to yeast Hir1p and Hir2p. These transcriptional co-repressors regulate cell cycle-dependent histone gene transcription(3), possibly by remodelling local chromatin structure. We report an interaction between HIRA and the transcription factor Pax3. Pax3 haploinsufficiency results in the mouse splotch and human Waardenburg syndrome (WSI and WSIII) phenotypes. Mice homozygous for Pax3 mutations die in utero with a phenocopy of DCS, or neonatally with neural tube defects. HIRA was also found to interact with core histones. Thus, altered stoichiometry of complexes containing HIRA may be important for the development of structures affected in WS and DCS.