Regulation of PSP/reg in rat pancreas: immediate and steady-state adaptation to different diets.
Pancreatic stone protein/reg protein (PSP/reg) is a secretory pancreatic protein of hitherto unknown function. It is precursor to a spontaneously precipitating peptide called pancreatic thread protein, which is found in protein plugs within the pancreatic ductal system. Increasing PSP/reg concentrations in pancreatic juice might augment the risk of intraductal plug formation and therefore be a condition predisposing to chronic pancreatitis. Malnutrition is associated with a high incidence of chronic pancreatitis in tropical countries. In a diet study with rats, we tested the hypothesis that protein malnutrition leads to increased PSP/reg concentrations in pancreatic juice. A highly sensitive and reliable enzyme-linked immunosorbent assay (ELISA) for rat PSP/reg was newly established. Male Sprague-Dawley rats were allocated to three nearly isocaloric experimental diets, which contained 0, 45, or 82% casein, respectively, or to a control diet (22% casein). We evaluated PSP/reg expression under these four dietary conditions on the RNA and on the protein level, performing a time-course study over a period of 28 days. Our results demonstrate that PSP/reg expression is not increased because of a protein-deficient diet if investigated under steady-state conditions. After a temporary increase in PSP/reg levels due to a carbohydrate-deficient high-protein diet, we could not find signs of a diet-dependent regulation of this protein. The regulation of PSP/reg thus differs from that of most other pancreatic secretory proteins. Our findings contradict earlier reports that had drawn conclusions based solely on messenger RNA levels.
Bimmler
D
D
Department of Surgery, University Hospital, Zürich, Switzerland. bda@chi.usz.ch
Angst
E
E
Valeri
F
F
Bain
M
M
Scheele
G A
GA
Frick
T W
TW
Graf
R
R
D000222:Adaptation, Physiological; D000681:Amylases / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D001835:Body Weight / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002364:Caseins; D018076:DNA, Complementary / Q000235:genetics; D004032:Diet; D004040:Dietary Carbohydrates; D004797:Enzyme-Linked Immunosorbent Assay; D051847:Lithostathine; D008297:Male; D009419:Nerve Tissue Proteins; D010179:Pancreas / Q000378:metabolism* / Q000502:physiology; D010189:Pancreatic Juice / Q000201:enzymology / Q000378:metabolism; D011488:Protein Deficiency; D012333:RNA, Messenger / Q000378:metabolism; D012339:RNA, Ribosomal, 28S / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D002135:Calcium-Binding Proteins; D002364:Caseins; D018076:DNA, Complementary; D004040:Dietary Carbohydrates; D051847:Lithostathine; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D012339:RNA, Ribosomal, 28S; C497616:Reg1a protein, rat; D000681:Amylases