Lifespan of mRNA in the Lens

Abstract

The degradation of mRNA during the differentiation of epithelial cells into fiber cells in the lens was studied and the lifespan of mRNA in lens fiber cells was estimated. Total RNA extracted from epithelial cells of the lens, fiber cells of the shallow cortex of the lens, and fiber cells of the deep cortex of the lens were used. RNA was more degraded in fiber cells of the deep cortex than in those of the shallow cortex. The expression of about 180 genes was more than 3-fold higher in fiber cells than in epithelial cells. Most mRNAs that were present at high levels in epithelial cells were also present at high levels in fiber cells of the shallow and deep cortex. Genes encoding crystallins and ribosomal proteins were highly expressed in epithelial cells and fiber cells. In addition, RT-PCR revealed that several genes were expressed with whole size even in the deep cortex. Electron microscopy detected ribosomes in differentiated fiber cells, which contained few membrane organelles. These results suggest that some mRNAs are protected from degradation in fiber cells of the lens and that these mRNAs persist for a long time and continue to be translated into proteins.