Quantitative autoradiographic studies in RNA and protein synthesis of dyskeratotic cells in morbus Darier

Dyskeratotic cells in morbus Darier demonstrate various fine structures indicating that the keratinization process has proceeded to a certain extent in these cells; that is, there are Odland bodies, a marginal thickening, and keratohyalin granules. Thus, acantholytic cells in the lower epidermis are supposed to perform an incomplete and premature keratinization, and eventually transform to corps ronds and grains. The biosynthesis of RNA and proteins in these dyskeratotic cells was studied by electron microscopic autoradiography after in vitro incubation. Biopsy specimens taken from typical lesions of 3 patients with morbus Darier were incubated in one of the following media for 1-2 hours at 37 degrees C in air containing 5% CO2: (1) Earle's MEM containing 200 muCi/ml of [3H]uridine; (2) Earle's balanced salt solution containing 200 muCi/ml of [3H]leucine or 200 muCi/ml of [3H]histidine. After pulse labeling of [3H]-leucine or [3H]histidine, some specimens were fixed, dehydrated, embedded in Epon, and then prepared for electron microscopic autoradiography. These 3 labeled precursors were incorporated into early acantholytic cells in the base and wall of lacunae, but they did not accumulate in completely isolated acantholytic and dyskeratotic cells including corps ronds and grains. The nuclei of corps ronds in an early stage occasionally took up uridine. The accumulation of [3H]histidine was most remarkable in the granular cells which were not dyskeratotic, and silver grains showed a strong tendency to accumulate over keratohyalin granules by 3-6 hours of chase. [3H]histidine did not incorporate in dyskeratotic cells, even though they possessed a large number of keratohyalin granules. From these findings it seems difficult to assume that these acantholytic cells keratinize themselves further by synthesizing their structural proteins under the control of the RNA system during their upward movement. On the contrary, it appears more likely that most dyskeratotic cells result from neighboring cells which have already keratinized to some extent.