Exocrine pancreatic secretion of phospholipid, menaquinone-4, and caveolin-1 in vivo.
The exocrine pancreas releases secretory products essential for nutrient assimilation. In addition to digestive enzymes, the release of lipoprotein-like particles containing the membrane trafficking protein caveolin-1 from isolated pancreatic explants has been reported. The present study examined: (1) if gastrointestinal hormones induce the apical secretion of phospholipid in vivo and (2) a potential association of caveolin-1 and the lipid-soluble vitamin K analog menaquinone-4 (MK-4) with these structures. Analysis of isolated acinar cells, purified zymogen granules, and pancreatic juice collected in vivo indicated the presence a caveolin-1 immunoreactive protein that was acutely released in response hormone stimulation. Chloroform-extracted fractions of pancreatic juice also contained high concentrations of MK-4 that was secreted in parallel to protein and phospholipid. The presence of caveolin-1 and MK-4 in the phospholipid fraction of pancreatic juice places these molecules in the secretory pathway of exocrine cells and suggests a physiological role in digestive enzyme synthesis and/or processing.
Thomas
Diana D H
DD
Department of Nutritional Sciences, University of Wisconsin, Madison, WI 53706, USA.
Krzykowski
Karen J
KJ
Engelke
Jean A
JA
Groblewski
Guy E
GE
D000818:Animals; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism*; D002478:Cells, Cultured; D002766:Cholecystokinin / Q000378:metabolism; D006490:Hemostatics / Q000378:metabolism; D006801:Humans; D008297:Male; D010179:Pancreas / Q000166:cytology / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012633:Secretin / Q000378:metabolism; D014020:Tissue Extracts / Q000737:chemistry / Q000378:metabolism; D024482:Vitamin K 2 / Q000031:analogs & derivatives* / Q000378:metabolism*
C495540:CAV1 protein, human; C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D006490:Hemostatics; D010446:Peptide Fragments; D010743:Phospholipids; D014020:Tissue Extracts; C410885:cholecystokinin 8; D024482:Vitamin K 2; D012633:Secretin; C030814:menatetrenone; D002766:Cholecystokinin