@entity11017 in the cochlea: expression and activity after XXXX exposition.

@entity801 @entity19 @entity4494 @entity6929 @entity581 @entity35 @entity11017 @entity4028
The matrix metalloproteinases (MMPs) are a family of proteins involved in the remodelling and homeostasis of the extracellular matrix. These proteases have been well studied in the retina and the brain, marking their importance in neuronal cell survival and death [Chintala (2006) Exp Eye Res 82:5-12; Candelario-Jalil et al. (2009) Neuroscience 158:983-994]. The neuroepithelia of the eye and the inner ear share common characteristics. Therefore, we hypothesized that MMPs could play a similar role in the cochlea as described in the retina. We focused on the localization and function of @entity11017 and @entity6929 in the cochlea, by determining their expression and activity under normal conditions and after cochlear damage via @entity4028 exposition. We examined their expression in 5-day-old @entity35 @entity35 cochleas by RT-PCR, real-time PCR, and Western blot. We used immunohistochemistry to investigate their location in the cochleas of adult C57BL/6 @entity19 . We also determined whether or not the exposure of the organs of Corti to @entity581 would change @entity11017 and @entity6929 expression patterns. Western blotting identified @entity11017 and @entity6929 in neonatal @entity4494 , stria vascularis, and to a lesser extent the organ of Corti. Neonatal mRNA expression of @entity11017 was approximately equivalent in all three tissues, while @entity6929 mRNA was highest in @entity4494 . Immunohistochemistry showed @entity11017 primarily in adult @entity4494 neurons and inner hair cells, while @entity6929 was found mainly in @entity4494 neurons, inner hair cells and supporting cells. Organs of Corti treated with @entity801 for 24 h showed an upregulation of @entity11017 and @entity6929 proteins, but did not show a significant upregulation of mRNA expression 3, 6, 12, 24, and 36 h after @entity801 exposure. Inhibition of MMP activity in organs of Corti incubated with an MMP inhibitor in organotypic cultures resulted in hair cell death-suggesting that a basal level of MMP activity is required for hair cell survival.
