Conversion of somatostatin-28 to somatostatin-14 during maturation of epithelial cells in the porcine jejunum.
Fractions of isolated epithelial cells were harvested from a segment of porcine jejunum by ten successive incubations with a chelating buffer. The cell fractions showed a progressive decrease in the activity of the brush-border enzymes, alkaline phosphatase and sucrase, with increasing incubation number but a progressive increase in the ability to incorporate labelled thymidine into DNA. Fractions enriched in cells from the crypt region (fractions 9 and 10) contained higher concentrations per mg protein of somatostatin-like immunoreactivity (1.8-fold), glucagon-like immunoreactivity (5.3-fold) and serotonin (3.0-fold) than fractions enriched in cells from the villus tip (fractions 1 and 2). Analysis of extracts of the fractions by gel filtration/radioimmunoassay showed that somatostatin-28 represented the predominant molecular form of somatostatin-like immunoreactivity in all cell fractions but the relative proportion of somatostatin-14 (and related metabolites) to somatostatin-28 was significantly higher (P less than 0.05) in fractions enriched in villus cells (fraction 1 and 2) than in fractions enriched in crypt cells (fractions 5-10). This result suggests that metabolism of somatostatin-28 to somatostatin-14 takes place during migration of the D cell from the crypt base to the villus tip. Heterogeneity in the somatostatin-14 region of the chromatograms indicates that the peptide may be further metabolized by the action of aminopeptidases.
Schäfer
G
G
Richter
G
G
Conlon
J M
JM
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002465:Cell Movement; D005934:Glucagon / Q000032:analysis; D007413:Intestinal Mucosa / Q000032:analysis / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007583:Jejunum / Q000032:analysis / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D008938:Mitosis; D012701:Serotonin / Q000032:analysis; D013004:Somatostatin / Q000378:metabolism*; D053561:Somatostatin-28; D013393:Sucrase / Q000378:metabolism; D013552:Swine
D012701:Serotonin; D013004:Somatostatin; D053561:Somatostatin-28; D005934:Glucagon; D000469:Alkaline Phosphatase; D013393:Sucrase