Occurrence of members of the insulin superfamily in central nervous system and digestive tract of protochordates.
Antisera specific for mammalian insulin-like growth factor 1 (IGF-1) and mammalian insulin and the double immunofluorescence technique were used for this study. IGF-1-like-immunoreactivity was localized in entero-endocrine cells in the gastro-intestinal tract of the protochordates Ciona intestinalis and Branchiostoma lanceolatum. Some of the specimens also showed IGF-1-like-immunoreactive (-IR) perikarya and fibers in the central nervous system. Whilst in rat endocrine pancreas, IGF-1-IR and insulin-IR occurred in different cell populations, in Ciona and Branchiostoma the vast majority of entero-endocrine cells and central neurons were IGF-1-like- +insulin-IR. A minor portion exhibited IGF-1-like-IR alone. For further characterization of the IGF-1-like-IR material, in Ciona intestinalis, peptides related to IGF-1 were identified by radioimmunoassay and gel chromatography. In accordance with the immunohistochemical results, IGF-I-like-IR was detected both in cerebral ganglion and in gastro-intestinal tract. Using acid gel chromatography, in Ciona gastro-intestinal tract the IGF-1-like-IR was found to occur in two peaks, with apparent molecular weights of approximately 16 kDa and 3 kDa. Absorption studies with insulin- and IGF-related peptides, with crude extracts and the peak material obtained after gel chromatography, indicated that the IGF-1-like peptides in Ciona are different from mammalian insulin and IGF-1. The findings are in accordance with the presence of a common insulin/IGF precursor molecule in protochordates.
Institute of Anatomy, Division of Neuroendocrinology, University of Zürich-Irchel, Switzerland.
M
M
Reinecke
D
D
Betzler
K
K
Drakenberg
S
S
Falkmer
V R
VR
Sara
D000818:Animals; D002490:Central Nervous System / Q000737:chemistry*; D002816:Chordata, Nonvertebrate / Q000737:chemistry*; D002845:Chromatography; D002938:Ciona intestinalis; D004064:Digestive System / Q000737:chemistry*; D007150:Immunohistochemistry; D007328:Insulin / Q000032:analysis*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D011817:Rabbits; D011869:Radioligand Assay
D007328:Insulin; D007334:Insulin-Like Growth Factor I