Production of trypsin by cells of the exocrine pancreas is paralleled by the expression of the KH protein vigilin.
Vigilin, a protein with a continuous series of 14 KH motifs, forms part of a multiprotein complex containing tRNA. Several lines of evidence have suggested that vigilin expression is enhanced in those cells which were actively engaged in protein synthesis. Accordingly, we show here by immunoelectronmicroscopy a close association of vigilin with the rough endoplasmic reticulum in rat pancreatic cells. Histological examination of these cells furthermore demonstrates the highest intensity of vigilin staining in the perinuclear, intranuclear, and basolateral regions where the endoplasmic reticulum is mainly amassed. In vivo challenge of starving rats fed prior to sacrifice raised in parallel the protein levels of both trypsin and vigilin when compared to unchallenged animals and was associated with enhanced expression of the vigilin gene. In contrast, in human and rat cell lines of pancreatic tumors with a constitutively high expression of vigilin no further stimulation by cholecystokinin treatment could be achieved. Our data provide circumstantial evidence that vigilin may play a crucial role in the ability of an organ, e.g., pancreas, to cope with the physiological demand to upregulate protein synthesis.
Kruse
C
C
Department of Medical Molecular Biology, Medical University of Lübeck, Germany.
Emmrich
J
J
Rumpel
E
E
Klinger
M H
MH
Grünweller
A
A
Rohwedel
J
J
Krammer
H J
HJ
Kühnel
W
W
Müller
P K
PK
D000818:Animals; D002352:Carrier Proteins; D017931:DNA Primers; D004435:Eating; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism / Q000648:ultrastructure; D018871:Endoplasmic Reticulum, Smooth / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D010179:Pancreas / Q000166:cytology / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000032:analysis; D016601:RNA-Binding Proteins; D051381:Rats; D014357:Trypsin / Q000032:analysis / Q000096:biosynthesis*; D014362:Trypsinogen / Q000032:analysis / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D014599:Uterus / Q000378:metabolism
D002352:Carrier Proteins; D017931:DNA Primers; D011506:Proteins; D016601:RNA-Binding Proteins; C075197:high density lipoprotein binding protein; D014362:Trypsinogen; D014357:Trypsin