Regulation of neuroendocrine gene expression by alternative RNA processing. Colocalization of calcitonin and calcitonin gene-related peptide in thyroid C-cells.

The generation of two discrete mRNAs encoding different polypeptide products in expression of the rat calcitonin, CGRP gene provides an example of developmentally determined alternative RNA processing events in the neuroendocrine system. Both mature mRNA transcripts and their peptide products, encoding either calcitonin or calcitonin gene-related peptide (CGRP) are co-produced in identical thyroid C-cells, in a ratio of 95:1, respectively. These data suggest that the generation of the two mRNAs reflect the actions of a factor(s) dictating alternative RNA processing events.