Expression of the integrin genes in the developing cochlea of rats

Integrins play an important role in the development of the cochlea. However, little is known about the expression pattern of integrins in the developing cochlear tissue. In this study, we investigated the dynamic expression profile of the integrin genes in the developing cochlear tissue of rats by Affymetrix microarrays and explored the role of the integrin genes in vitro by using antisense oligonucleotides. It was demonstrated that the α1, α7, αv, β3, and β4 genes were expressed in the developing cochlear tissue of rats. Inhibition of the integrin expression with antisense oligonucleotides against αv, α7, β3, and β4, respectively, in cochlear sensorineural epithelial cells significantly decreased the [3H]thymidine incorporation, suggesting that these integrins are involved in cell growth and proliferation. Inhibition of the αv and β4 integrins significantly decreased the transcription of nuclear factor-kappa B (NF-κB, a signal molecule involved in cell growth and proliferation) induced by epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), respectively. It suggests that EGF-induced cell growth is dependent upon the αv integrin whereas bFGF-induced cell growth is dependent upon the β4 integrin in the cochlear tissue during the development of the inner ear.