Circulating and tissue forms of the intestinal growth factor, glucagon-like peptide-2.
Glucagon-like peptide-2 (GLP-2) has recently been identified as a stimulator of intestinal epithelial growth, prompting the development of RIA and HPLC methodologies to study this peptide in more detail. A GLP-2-specific antiserum (UTTH-7) was developed that recognizes amino acids 25-30 of human and rat GLP-2-(1-33). UTTH-7 cross-reacts with N- and C-terminally modified forms of GLP-2, proglucagon, and the major proglucagon fragment. Analysis of rat ileal extracts demonstrated the presence of GLP-2-(1-33) as well as significant amounts of GLP-2-(3-33) (16 +/- 7% of total GLP-2). The level of total immunoreactive GLP-2 in plasma from fasted rats was 700 +/- 71 pg/ml, and this increased 3.6-fold (P < 0.001) in 24-h fed rats. HPLC analysis demonstrated the presence of both GLP-2-(1-33) and GLP-2-(3-33) in plasma from fasted rats, with increments in both peptides in plasma from fed rats. Immunoreactive GLP-2 increased in plasma from human subjects 2 h after a meal, rising from 851 +/- 230 to 1106 +/- 211 pg/ml (P < 0.05); 15 +/- 4% of this immunoreactivity was accounted for by the presence of intact GLP-2. HPLC showed the presence of both GLP-2-(1-33) and GLP-2-(3-33) in plasma from fed humans. Incubation of human GLP-2-(1-33) with the enzyme dipeptidylpeptidase IV resulted in liberation of GLP-2-(3-33), whereas replacement of Ala2 with Gly2 prevented this cleavage. Thus, while GLP-2-(1-33) is a major circulating and tissue form of GLP-2, GLP-2-(3-33) is a significant component ofimmunoreactive GLP-2 in both intestine and plasma.
Brubaker
P L
PL
Department of Physiology, University of Toronto, Ontario, Canada. p.brubaker@utoronto.ca
Crivici
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Izzo
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A
Ehrlich
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Tsai
C H
CH
Drucker
D J
DJ
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D018819:Dipeptidyl Peptidase 4 / Q000494:pharmacology; D004435:Eating; D005215:Fasting; D005260:Female; D053767:Glucagon-Like Peptide 2; D004763:Glucagon-Like Peptides; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010455:Peptides / Q000097:blood* / Q000235:genetics / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats
D053767:Glucagon-Like Peptide 2; D010455:Peptides; D004763:Glucagon-Like Peptides; D018819:Dipeptidyl Peptidase 4