Preptin derived from proinsulin-like growth factor II (proIGF-II) is secreted from pancreatic islet beta-cells and enhances insulin secretion.
Pancreatic islet beta-cells secrete the hormones insulin, amylin and pancreastatin. To search for further beta-cell hormones, we purified peptides from secretory granules isolated from cultured murine beta TC6-F7 beta-cells. We identified a 34-amino-acid peptide (3948 Da), corresponding to Asp(69)-Leu(102) of the proinsulin-like growth factor II E-peptide, which we have termed 'preptin'. Preptin, is present in islet beta-cells and undergoes glucose-mediated co-secretion with insulin. Synthetic preptin increases insulin secretion from glucose-stimulated beta TC6-F7 cells in a concentration-dependent and saturable manner. Preptin infusion into the isolated, perfused rat pancreas increases the second phase of glucose-mediated insulin secretion by 30%, while anti-preptin immunoglobulin infusion decreases the first and second phases of insulin secretion by 29 and 26% respectively. These findings suggest that preptin is a physiological amplifier of glucose-mediated insulin secretion.
Buchanan
C M
CM
School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Phillips
A R
AR
Cooper
G J
GJ
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002460:Cell Line; D002469:Cell Separation; D015536:Down-Regulation / Q000276:immunology; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000819:agonists / Q000276:immunology / Q000378:metabolism*; D000078790:Insulin Secretion; D007335:Insulin-Like Growth Factor II / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology*; D010477:Perfusion; D011498:Protein Precursors / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D022142:Secretory Vesicles / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism
D000906:Antibodies; D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; C443100:preptin; C066038:proinsulin-like growth factor II; D007335:Insulin-Like Growth Factor II; D005947:Glucose