RNA metabolism in cultures of corneal stromal cells from patients with keratoconus.
Total cellular RNA was extracted from cultured keratoconus and normal human corneal stromal cells. The translational activity of these RNAs was examined in a cell-free translation system derived from reticulocyte lysate. Results indicated that keratoconus cells can be separated into two groups, as has been shown previously. Group I keratoconus cells contained the same amount of total RNA as normal cells. RNA activity and the rate of mRNA synthesis in this group of keratoconus cells were also normal. By these criteria it seems that the protein synthesizing system is functioning properly, and group I keratoconus cells should have a normal rate of protein synthesis. These results correlate well with previous findings. Group II keratoconus cells, in contrast, contained more RNA than normal cells. The translational efficiency of RNA was so markedly reduced that the elevation in RNA content did not compensate for the decrease in translational efficiency. It is likely that the reduced protein and collagen synthesis in this group of cells is related to the reduction in the RNA activity. An inhibitory component was present in the keratoconus RNA which affected synthesis of all proteins and suppressed translation of normal RNA.