A synthetic peptide derived from a COOH-terminal domain of the insulin receptor specifically enhances insulin receptor signaling.
The role of the insulin receptor COOH-terminal domain in the regulation of insulin signal transduction was explored with a variety of synthetic peptides. One of the peptides, termed peptide HC, whose structure corresponds to residues 1293-1307 of the insulin proreceptor sequence, enhanced insulin-stimulated autophosphorylation of the insulin receptor in cell-free systems and in semipermeabilized Chinese hamster ovary (CHO) cells that had been transfected with an expression plasmid encoding the human insulin receptor (CHO/HIRc) at concentrations where there was no detectable effect on basal autophosphorylation levels or on receptor dephosphorylation. A lipophilic analogue of peptide HC, stearyl peptide HC, added to intact CHO/HIRc cells enhanced significantly insulin-stimulated insulin receptor autophosphorylation while having no effect on ligand-stimulated receptor phosphorylation in CHO cells overexpressing either the IGF-1 receptor or epidermal growth factor receptor. Addition of stearyl peptide HC to CHO/HIRc cells resulted in a 2.4 +/- 0.3-fold increase in the amount of insulin-stimulated phosphatidylinositol 3-kinase detected in anti-IRS-1 immunoprecipitates and a 2.1 +/- 0.6-fold increase in the levels of tyrosine phosphorylation of mitogen-activated protein kinase in response to insulin. Finally, a derivative of peptide HC coupled to a biotin moiety was prepared and showed to bind with the beta-subunit of the wild-type insulin receptor and a truncated receptor that lacks 43 amino acids from its carboxyl terminus. However, there was little binding, if any, of the peptide with the IGF-1 receptors or the epidermal growth factor receptors. Taken together, our data demonstrate that a pentadecapeptide related to the carboxyl terminus of the insulin receptor binds to the insulin receptor beta-subunit and that this interaction may contribute to the increased receptor's intrinsic activity and signal transduction.
Kole
H K
HK
Diabetes Section, Laboratory of Clinical Physiology, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA. Bernierm@vax.grc.nia.nih.gov
Liotta
A S
AS
Kole
S
S
Roth
J
J
Montrose-Rafizadeh
C
C
Bernier
M
M
D000818:Animals; D001710:Biotin; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D006224:Cricetinae; D006801:Humans; D007328:Insulin / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010446:Peptide Fragments / Q000378:metabolism*; D011972:Receptor, Insulin / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction; D013229:Stearic Acids; D014443:Tyrosine / Q000378:metabolism
D007328:Insulin; D010446:Peptide Fragments; D013229:Stearic Acids; C102586:insulin receptor (1293-1307); D014443:Tyrosine; C031183:stearic acid; D001710:Biotin; D011972:Receptor, Insulin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases