Characterization of insulinlike growth factor I produced by fetal rat pancreatic islets.
Pancreatic islets were prepared from 22-day-old rat fetuses. After 5 days of culture in dishes allowing cell attachment, neoformed islets were kept free floating in RPMI-1640 medium (16.5 mM glucose, 1% fetal calf serum). The islets were then pulsed with [3H]leucine and [35S]methionine for 24 h. The conditioned medium was acidified with acetic acid (final pH 2.7), desalted, concentrated, and gel filtered on Bio-Gel P100 in acid conditions. The radioactive material that comigrated with immunoreactive insulinlike growth factor I (IGF-I) produced by the islets was pooled, concentrated, and further characterized by reverse-phase high-performance liquid chromatography on a C18 Bondapak column with a linear gradient of acetonitrile (20-80%). The radioactive material that eluted as pure IGF-I (40% acetonitrile) was further studied by chromatofocusing on a Pharmacia PBE 94 column. A sharp radioactive peak containing [3H]leucine and [35S]methionine was eluted at pH 8.55. This material was immunoprecipitated with an antiserum to IGF-I. This study demonstrated that fetal islet cells synthesize molecules that are, by several criteria, equivalent to native IGF-I.
Scharfmann
R
R
Institut National de la Santé et de la Recherche Médicale (Unit 30), Hôpital des Enfants Malades, Paris, France.
Corvol
M
M
Czernichow
P
P
D000818:Animals; D002478:Cells, Cultured; D002845:Chromatography; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005333:Fetus; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000302:isolation & purification; D007515:Islets of Langerhans / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000096:biosynthesis*; D013462:Sulfur Radioisotopes; D014316:Tritium
D013002:Somatomedins; D013462:Sulfur Radioisotopes; D014316:Tritium; D007334:Insulin-Like Growth Factor I; D008715:Methionine; D007930:Leucine