EXPRESSION OF TRYPSIN BY EPITHELIAL-CELLS OF VARIOUS TISSUES, LEUKOCYTES, AND NEURONS IN HUMAN AND MOUSE

It has long been believed that trypsin is normally synthesized only in the pancreas, In the present study, expression of trypsin in human an d mouse nonpancreatic tissues was examined, Northern blot analysis of normal human tissues indicated that the trypsin gene is expressed at h igh levels in the pancreas and spleen and considerably in the small in testine, However, in situ hybridization and immunohistochemistry demon strated that trypsin is widely expressed in epithelial cells of the sk in, esophagus, stomach, small intestine, lung, kidney, liver, and extr ahepatic bile duct, as well as splenic and neuronal cells. In the sple en, trypsin message was detected in the nerve cells of the hippocampus and cerebral cortex, Analysis by gelatin zymography confirmed the pre sence of a latent or an active form of trypsin in various normal mouse tissues. Reverse transcription-polymerase chain reaction analysis als o confirmed the expression of trypsin genes in the spleen, liver, kidn ey, and brain of normal mice. Such a broad distribution of trypsin sug gests its general roles in the maintenance of normal epithelial cell f unctions, the immune defense system, and the central nervous system.