Unconventional Myosins

All vertebrate inner ears possess sensory hair cells. These cells transduce sound into electrical impulses that are used by the nervous system. Although these cells all share some basic features such as an apical hair bundle and basal nerve synapses, there is much diversity in hair cells, both within an organism and between vertebrate taxa. Our lab studies this diversity as a means to understand hearing in general and to examine evolutionary trends.

Current studies in the lab focus on unconventional myosins, a group of motor proteins critical to hair cell structure and function. Two of these proteins, myosins VI and VIIa, have been implicated in hereditary deafness in both humans and mice. We use immunocytochemistry to localize these myosins in ears from diverse groups of fishes. Myosin antibodies were kindly provided by Dr. Tama Hasson.

The figures on this page show a few examples of myosin VI distribution in fish ears. Myosin labels are shown in red, and actin (the major hair bundle protein) is shown in green.
 
  Semicircular canal crista from a sea lamprey (Petromyzon marinus), a primitive jawless fish.
   
 
 

Saccular epithelium from an oscar (Astronotus ocellatus), a teleost with poor hearing
   
 
  Lagenar epithelium from a zebrafish (Danio rerio), a teleost with good hearing.

Our studies show that both of these proteins are present in hair cells of fishes, indicating evolutionary conservation of these important molecules. We are currently exploring differences in intracellular distribution of these proteins that should shed further light on their function in hair cells.


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