Insulin and insulin-like growth factor 1 (IGF-1) are closely related hormones involved in the regulation of metabolism and growth. They elicit their functions through activation of tyrosine kinase-type receptors: insulin receptors (IR-A and IR-B) and IGF-1 receptor (IGF-1R). Despite similarity in primary and three-dimensional structures, insulin and IGF-1 bind the noncognate receptor with substantially reduced affinity. We prepared [d-HisB24, GlyB31, TyrB32]-insulin, which binds all three receptors with high affinity (251 or 338% binding affinity to IR-A respectively to IR-B relative to insulin and 12.4% binding affinity to IGF-1R relative to IGF-1). We prepared other modified insulins with the aim of explaining the versatility of [d-HisB24, GlyB31, TyrB32]-insulin. Through structural, activity, and kinetic studies of these insulin analogs, we concluded that the ability of [d-HisB24, GlyB31, TyrB32]-insulin to stimulate all three receptors is provided by structural changes caused by a reversed chirality at the B24 combined with the extension of the C terminus of the B chain by two extra residues. We assume that the structural changes allow the directing of the B chain C terminus to some extra interactions with the receptors. These unusual interactions lead to a decrease of dissociation rate from the IR and conversely enable easier association with IGF-1R. All of the structural changes were made at the hormones' Site 1, which is thought to interact with the Site 1 of the receptors. The results of the study suggest that merely modifications of Site 1 of the hormone are sufficient to change the receptor specificity of insulin.

• Klíčová slova
• Site 1, binding, insulin, insulin receptor, insulin-like growth factor (IGF), kinetics, protein design, structure-function,
• MeSH
• insulinu podobný růstový faktor I chemie   genetika   metabolismus   MeSH
• inzulin agonisté   metabolismus   MeSH
• kinetika MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• receptor IGF typ 1 MeSH
• receptor inzulinu chemie   genetika   metabolismus   MeSH
• receptory somatomedinů chemie   genetika   metabolismus   MeSH
• sekvence aminokyselin MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• IGF1R protein, human MeSH Prohlížeč
• insulinu podobný růstový faktor I MeSH
• inzulin MeSH
• receptor IGF typ 1 MeSH
• receptor inzulinu MeSH
• receptory somatomedinů MeSH

A significant drawback of the exogenous administration of insulin to diabetics is the non-physiological profile of insulin action resulting in the insufficient suppression of hepatic glucose production, which is the main contributing factor to diabetic hyperglycemia under fasting conditions and the basis of the challenge to restore a more physiological glucose profile in diabetes. The insulin receptor (IR) exists in two alternatively spliced variants, IR-A and IR-B, with different tissue distribution. While peripheral tissues contain different proportions of both isoforms, hepatic cells almost exclusively contain IR-B. In this respect, IR-B-selective insulin analogs would be of great interest for their potential to restore more natural metabolic homeostasis in diabetes. Recent advances in the structural biology of insulin and IR have provided new clues for understanding the interaction of both proteins. This article discusses and offers some structural perspectives for the design of specific insulin analogs with a preferential binding to IR-B.

• Klíčová slova
• CT-peptide, IR-A, IR-B, binding affinity, exon 11, insulin analog, insulin receptor isoform,
• Publikační typ
• časopisecké články MeSH

Insulin and insulin-like growth factors I and II are closely related protein hormones. Their distinct evolution has resulted in different yet overlapping biological functions with insulin becoming a key regulator of metabolism, whereas insulin-like growth factors (IGF)-I/II are major growth factors. Insulin and IGFs cross-bind with different affinities to closely related insulin receptor isoforms A and B (IR-A and IR-B) and insulin-like growth factor type I receptor (IGF-1R). Identification of structural determinants in IGFs and insulin that trigger their specific signaling pathways is of increasing importance in designing receptor-specific analogs with potential therapeutic applications. Here, we developed a straightforward protocol for production of recombinant IGF-II and prepared six IGF-II analogs with IGF-I-like mutations. All modified molecules exhibit significantly reduced affinity toward IR-A, particularly the analogs with a Pro-Gln insertion in the C-domain. Moreover, one of the analogs has enhanced binding affinity for IGF-1R due to a synergistic effect of the Pro-Gln insertion and S29N point mutation. Consequently, this analog has almost a 10-fold higher IGF-1R/IR-A binding specificity in comparison with native IGF-II. The established IGF-II purification protocol allowed for cost-effective isotope labeling required for a detailed NMR structural characterization of IGF-II analogs that revealed a link between the altered binding behavior of selected analogs and conformational rearrangement of their C-domains.

• Klíčová slova
• insulin, insulin receptor, insulin-like growth factor (IGF), nuclear magnetic resonance (NMR), structural biology, structure-function,
• MeSH
• CD antigeny chemie   genetika   metabolismus   MeSH
• insulinu podobný růstový faktor II chemie   genetika   metabolismus   MeSH
• lidé MeSH
• missense mutace MeSH
• protein - isoformy chemie   genetika   metabolismus   MeSH
• proteinové domény MeSH
• receptor IGF typ 1 chemie   genetika   metabolismus   MeSH
• receptor inzulinu chemie   genetika   metabolismus   MeSH
• rekombinantní proteiny chemie   genetika   metabolismus   MeSH
• substituce aminokyselin MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CD antigeny MeSH
• IGF2 protein, human MeSH Prohlížeč
• INSR protein, human MeSH Prohlížeč
• insulinu podobný růstový faktor II MeSH
• protein - isoformy MeSH
• receptor IGF typ 1 MeSH
• receptor inzulinu MeSH
• rekombinantní proteiny MeSH