Molecular Histo-cytochemical Analysis of Gene Transcription Factors Reflecting in the Regulation of Functional Differentiation of the Cell

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1. During the gestation, the ehorionie cells of placentas differentiate into the villous cells which express the prolactin family protein gene. To clarify whether difference of cellular distribution of a transcription factor, Pit-1, which enhances expression of the gene reflects the state of the differentiating cells, we performed Southwestern histochemistry of which method localizes DNA-binding transcription factors. In rat placentas at the late gestational days, the villous cells possessing intranuclear Pit-1 seemed to be identical to the villous cells expressing the prolactin family protein genes in their cytoplasm.2. To understand further the relationship between nuclear components and intranuclear state of transcription factors in differentiating cells, Southwestern histochemistry was performed at ultrastruetural level. The DNA-binding Pit 1 was localized in the euchroraatin of nuclei both of the chorionic villous cells which express prolactin family protein genes and of anterior … More pituitary cells which express prolactin gene. It is suggested that the localization of DNA-binding transcription factors in euchromatin in which the active chromatins are located would be essential for functional differentiation of the cells.3. To analyze a relationship of intranuclear sites between DNA-binding transcription factors and the genomic DNAs or the transcripts, as a model, two different nucleic acids were ultrastructurally localized. Since 45S rRNA is stoichyometrically spliced to 18S rRNA and 28S rRNA, we examined simultaneous localization of both rRNAs in mouse testicular tissue sections using different sized colloidal gold particles in post-embedding method of in situ hybridization. Electron microscopic in situ hybridization revealed that different distribution between these rRNAs was seen in the nucleoli of Sertoli cells. Our findings suggest that the mutual distribution of nuclear substances with different metabolisms, such as the rRNAs as well as the transcription factors and the transcripts, would be quantitatively demonstrated in the nuclei by the method. Less