PRODUCTION OF TRYPSIN BY CELLS OF THE EXOCRINE PANCREAS IS PARALLELEDBY THE EXPRESSION OF THE KH PROTEIN VIGILIN

Vigilin, a protein with a continuous series of 14 KH motifs, forms par t of a multiprotein complex containing tRNA. Several lines of evidence have suggested that vigilin expression is enhanced in those cells whi ch were actively engaged in protein synthesis [1, 2]. Accordingly, we show here by immunoelectronmicroscopy a close association of vigilin w ith the rough endoplasmic reticulum in rat pancreatic cells. Histologi cal examination of these cells furthermore demonstrates the highest in tensity of vigilin staining in the perinuclear, intranuclear, and baso lateral regions where the endoplasmic reticulum is mainly amassed, In vivo challenge of starving rats fed prior to sacrifice raised in paral lel the protein levels of both trypsin and vigilin when compared to un challenged animals and was associated with enhanced expression of the vigilin gene. In contrast, in human and rat cell lines of pancreatic t umors with a constitutively high expression of vigilin no further stim ulation by cholecystokinin treatment could be achieved. Our data provi de circumstantial evidence that vigilin may play a crucial role in the ability of an organ, e.g., pancreas, to cope with the physiological d emand to upregulate protein synthesis. (C) 1998 Academic Press.