Growth-controlling molluscan neurons produce the precursor of an insulin-related peptide.
Insulin and related peptides are key hormonal integrators of growth and metabolism in vertebrates. There is little biochemical evidence for insulin-related peptides in invertebrates, apart from insects for which definitive structural information on these peptides (prothoracicotropic hormone, PTTH) has recently been obtained. We report here the first complete complementary DNA-derived primary structure of a preproinsulin-related protein from identified neurons in an invertebrate, the mollusc Lymnaea stagnalis. We have demonstrated by in situ hybridization that transcription of the gene for this molluscan insulin-related peptide (MIP) occurs in the cerebral light-green cells, giant neuroendocrine cells involved in the control of growth, as well as in a pair of neuroendocrine cells called the canopy cells. The insulin-related peptide precursor has the same overall structure as its vertebrate counterparts. The discovery of insulin-related peptides in invertebrates substantiates the evidence for a widespread and early evolutionary origin of the insulin superfamily.
Smit
A B
AB
Biologisch Laboratorium, Vrije Universiteit, Amsterdam, The Netherlands.
Vreugdenhil
E
E
Ebberink
R H
RH
Geraerts
W P
WP
Klootwijk
J
J
Joosse
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D007328:Insulin; D008195:Lymnaea / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D011384:Proinsulin / Q000096:biosynthesis* / Q000235:genetics; D011498:Protein Precursors / Q000096:biosynthesis* / Q000235:genetics; D021382:Protein Sorting Signals / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D007328:Insulin; D011498:Protein Precursors; D021382:Protein Sorting Signals; C013737:preproinsulin; D004247:DNA; D011384:Proinsulin