CEXS-UPF: Fishes do not suffer hearing loss thanks to the retinoic acid

CEXS-UPF: Fishes do not suffer hearing loss thanks to the retinoic acid

News from CEXS-UPF

Hair cells are found in the inner ear and are responsible of capturing auditory and balance sensory inputs. These cells die after acoustic trauma, ototoxic drugs or aging disease. Unfortunately, mammals' hair cells have no regenerative ability, being therefore deafness a common illness in elderly people. Fishes, however, are able to regenerate hair cells. Knowing how this regenerative capacity works leads to new perspectives in the research of the treatment of hearing loss.

The Developmental Biology Group of the Department of Experimental and Health Sciences (DCEXS) has discovered that the retinoic acid (RA) pathway triggers the regeneration of damaged hair cells in zebrafish. The results are published in the Journal of Neuroscience.

Regenerative properties of retinoic acid have been widely studied in organs such as amphibian's limbs or heart. However, its regenerative function in the ear of fish remained unknown. By means of genetic and pharmacological inhibition, the team led by Berta Alsina has shown that this acid is essential for cell regeneration in zebrafish inner ear. When damaging hair cells, the researchers have seen that the RA pathqay is activated, repressing the expression of p27 kip and sox2 genes, key compounds in the development of hair cells. This repression allows the generation of new hair cells for reconstructing the damaged sensory organ.

These findings are helpful to understand the molecular mechanisms underlying cell regeneration of non-mammalian vertebrates and point to the retinoic acid pathway as a target in the research of therapeutic agents for hearing recovery. Besides its role in the inner ear, the study shows the regenerative role of retinoic acid in the lateral line of the fish, a sensory organ that allows them to detect the movement of water around them.
More information:

Reference work:
Davide Rubbini, Àlex Robert-Moreno, Esteban Hoijman, Berta Alsina. Retinoic Acid Signaling Mediates Hair Cell Regeneration by Repressing p27kip and sox2 in Supporting Cells. The Journal of Neuroscience, November 2015.  doi: 10.1523/JNEUROSCI.1099-15.2015