Research Interests

Previously, my research has mainly concentrated on the genetics of sensory hair cell function in the mouse. Spontaneously occurring mouse mutants have been instrumental in identifying genes affecting hair cell structure and function.

In mice and humans, the perception and transmission of acoustic stimuli take place in the cochlea (Fig.1a), which is located in the inner ear and anatomically connected to the vestibular organ. Within the cochlea, sensory hair cells (Fig.1a arrows) have precisely organized actin-filled projections called stereocilia, which are arranged in bundles on the apical surface of each cell (Fig.1b; enlarged view of bundles of cochlear sensory hair cells). The upper surface of the hair cell is bathed in a fluid called endolymph. The endolymph is very high in potassium and low in sodium and it is maintained at a high positive resting potential of (100MmV), which is essential for normal hair cell function.

The Varitint-waddler mouse mutant

Mucolipin 3 is the gene mutated in the classical semidominant mouse mutant varitint-waddler (Va), leading to deafness and pigmentation defects (Di Palma et al., 2002; PDF, Commentary). The gene encodes a putative six-transmembrane protein with sequence similarities to the mucolipin members of the transient-receptor-potential ion channel superfamily (TRP-ML). Our data show that Mucolipin 3 is critical for hair cell function and it localizes to cytoplasmic compartments of hair cells, the plasma membrane of stereocilia as well as melanocytes of the stria vascularis (Di Palma unpublished observations).