Scientists of Helmholtz Zentrum München, led by Martin Hrabé de Angelis, director of the Institute of Experimental Genetics, have developed a new mouse model for progressive hearing loss. This is caused by the alteration of a single base of a specific microRNA seed region. Mice carrying this miR-96 mutation suffer progressive hearing loss as they get older and if they carry two of these mutants, their sensory hair cells are impaired from birth.
A number of genes associated with hearing loss were already known. “However, we were very surprised when with our new mouse model we discovered this new class of genes, microRNA, as the genetic cause,” said Helmut Fuchs, who conceived the idea of this mouse model and is scientific-technical head of the German Mouse Clinic at Helmholtz Zentrum München.
The mice were bred using the ENU method in which male mice are administered N-ethyl-N-nitrosurea (ENU), thus influencing the DNA of their sperm. Successor generations develop dominant or recessive mutations. The German researchers made the mouse model available to colleagues at the Wellcome Trust Sanger Institute in Cambridge, who uncovered the association with the miR-96 mutation.
“We assume that our mouse model will be of far-reaching significance for the development of treatment strategies against genetically-caused progressive hearing loss in humans,” Fuchs said. Colleagues from Spain have confirmed this assumption in examinations of patients diagnosed with progressive hearing loss. In these people, the microRNA cluster Mirn96 was mutated in the same seed region as in the mouse model. Now, with the aid of this mouse model, the international research consortium hopes to identify factors which are necessary for long-term survival of hair cells and thus to find new approaches for treatment of progressive hearing loss.