Multiple functions for Eya3 in mammalian organism

The important function of Eya (eyes absent) in eye development of D.melanogaster is well known, the function of its mammalian orthologs Eya1-4 is only partially understood. Yet, no phenotype for Eya2 and Eya3 in humans or mouse have been described. In our study we analysed new Eya-deficient mouse model generated by insertional mutagenesis. Expression analysis of Eya3 by in-situ hybridizations and β-Gal-staining revealed a broad expression of the gene throughout development, e.g. in brain, eyes, branchial arches, somites and limbs. This diverse expression pattern suggests pleiotropic effects of Eya3 in mammalian organisms. In contrast to D. melanogaster, a close examination of the eye by various methods did not show any obvious ocular defects in mutant animals. A broad phenotypical characterization of homozygous mutants displayed decreased body weight and body length. Additionally, behavioral changes as a educed forward locomotor activity and altered exploratory behaviour were identified. A significant reduction of forelimb grip strength and an impairment of cardiac processes in Eya3-/- mice suggest a role for Eya3 in muscle development and heart function. Our results implicate that Eya3 plays various roles outside the eye with effects particularly on heart and muscle function in the mouse. Keywords: Eya3-deficient mice, cDNA microarrays, brain, heart, muscle analysis of 4 Eya3 mutant mice versus a pool of 5 wildtype animals; brain, heart, and muscle; 8 hybridisations for each tissue: two technical replicates for each mutant animal including one dye-swap experiments