Prothymosin alpha location in the proliferative compartments of the digestive tract epithelium

Prothymosin alpha is a polypeptide whose function is still a matter of deba te. The present paper represents the first morphological description of the prothymosin alpha distribution in the human and rat digestive tract tissue s using immunohistochemical techniques. In these epithelia prothymosin alph a immunostaining was localized in the nuclei of the proliferating cells, e. g, in the basal layer cells of the oesophagus, cells of the isthmus and the neck of the gastric glands, and crypt cells in the small and large intesti nes. At the ultrastructural level, prothymosin alpha immunolabelling was ev ident in the nucleus, being confined to euchromatin. The present data indic ates that prothymosin alpha expression in the digestive tract epithelia is associated with proliferating cell populations. In agreement with this hypo thesis, we found that the patterns of distribution of prothymosin alpha and proliferating cell nuclear antigen were similar. The distribution of proth ymosin immunoreactivity was also similar to that obtained for bromodeoxyuri dine when the animal was sacrificed 12 hr after injection. The finding that intracellular distribution of the prothymosin alpha in the digestive tract epithelia is identical to that found in other tissues supports the idea th at prothymosin alpha must play a universal role in proliferating cells.