Inzulinu podobný růstový faktor 2 patří, spolu s několika dalšími inzulinu podobnými peptidy, do evolučně konzervované rodiny signalizačních molekul, které jsou nezbytné pro normální buněčnou proliferaci a vývoj mozku. Dřívější studie se zaměřovaly převážně na jeho úlohu v embryonálním vývoji a kancerogenezi. V posledních letech byly odhaleny nové poznatky týkající se role inzulinu podobného růstového faktoru 2 v centrální nervové soustavě, zejména jeho význam pro učení, konsolidaci paměti a zlepšení kognitivních funkcí. I přes stále ne zcela prozkoumanou fyziologickou roli inzulinu podobného růstového faktoru 2 se v našem článku snažíme podrobněji popsat a vysvětlit jeho známé funkce a diskutovat jeho potenciální využití, včetně možné aplikace v léčbě neurodegenerativních onemocnění.
Insulin-like growth factor 2 (IGF2), along with several other insulin-like peptides, belongs to an evolutionarily conserved family of signalling molecules essential for normal cell proliferation and brain development. Previous studies have mainly focused on its role in embryonic development and carcinogenesis. In recent years, new insights revealed the role of IGF2 in the central nervous system, particularly its importance in learning, memory consolidation and enhancement. Despite the still not fully explored physiological role of IGF2, in this article we aim to describe and explain its known functions in more detail and discuss its potential uses, including its possible application in the treatment of neurodegenerative diseases.
Preptin, a 34-amino acid peptide derived from pro-IGF2, is believed to influence various physiological processes, including insulin secretion and the regulation of bone metabolism. Despite its recognized involvement, the precise physiological role of preptin remains enigmatic. To address this knowledge gap, we synthesized 16 analogs of preptin, spanning a spectrum from full-length forms to fragments, and conducted comprehensive comparative activity evaluations alongside native human, mouse and rat preptin. Our study aimed to elucidate the physiological role of preptin. Contrary to previous indications of broad biological activity, our thorough analyses across diverse cell types revealed no significant biological activity associated with preptin or its analogs. This suggests that the associations of preptin with various diseases or tissue-specific abundance fluctuations may be influenced by factors beyond preptin itself, such as higher levels of IGF2 or IGF2 proforms present in tissues. In conclusion, our findings challenge the conventional notion of preptin as an isolated biologically active molecule and underscore the complexity of its interactions within biological systems. Rather than acting independently, the observed effects of preptin may arise from experimental conditions, elevated preptin concentrations, or interactions with related molecules such as IGF2.
- MeSH
- insulinu podobný růstový faktor II * metabolismus MeSH
- inzulin metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- myši MeSH
- peptidové fragmenty metabolismus MeSH
- proteinové prekurzory metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVE: The insulin/IGF superfamily is conserved across vertebrates and invertebrates. Our team has identified five viruses containing genes encoding viral insulin/IGF-1 like peptides (VILPs) closely resembling human insulin and IGF-1. This study aims to characterize the impact of Mandarin fish ranavirus (MFRV) and Lymphocystis disease virus-Sa (LCDV-Sa) VILPs on the insulin/IGF system for the first time. METHODS: We chemically synthesized single chain (sc, IGF-1 like) and double chain (dc, insulin like) forms of MFRV and LCDV-Sa VILPs. Using cell lines overexpressing either human insulin receptor isoform A (IR-A), isoform B (IR-B) or IGF-1 receptor (IGF1R), and AML12 murine hepatocytes, we characterized receptor binding, insulin/IGF signaling. We further characterized the VILPs' effects of proliferation and IGF1R and IR gene expression, and compared them to native ligands. Additionally, we performed insulin tolerance test in CB57BL/6 J mice to examine in vivo effects of VILPs on blood glucose levels. Finally, we employed cryo-electron microscopy (cryoEM) to analyze the structure of scMFRV-VILP in complex with the IGF1R ectodomain. RESULTS: VILPs can bind to human IR and IGF1R, stimulate receptor autophosphorylation and downstream signaling pathways. Notably, scMFRV-VILP exhibited a particularly strong affinity for IGF1R, with a mere 10-fold decrease compared to human IGF-1. At high concentrations, scMFRV-VILP selectively reduced IGF-1 stimulated IGF1R autophosphorylation and Erk phosphorylation (Ras/MAPK pathway), while leaving Akt phosphorylation (PI3K/Akt pathway) unaffected, indicating a potential biased inhibitory function. Prolonged exposure to MFRV-VILP led to a significant decrease in IGF1R gene expression in IGF1R overexpressing cells and AML12 hepatocytes. Furthermore, insulin tolerance test revealed scMFRV-VILP's sustained glucose-lowering effect compared to insulin and IGF-1. Finally, cryo-EM analysis revealed that scMFRV-VILP engages with IGF1R in a manner closely resembling IGF-1 binding, resulting in a highly analogous structure. CONCLUSIONS: This study introduces MFRV and LCDV-Sa VILPs as novel members of the insulin/IGF superfamily. Particularly, scMFRV-VILP exhibits a biased inhibitory effect on IGF1R signaling at high concentrations, selectively inhibiting IGF-1 stimulated IGF1R autophosphorylation and Erk phosphorylation, without affecting Akt phosphorylation. In addition, MFRV-VILP specifically regulates IGF-1R gene expression and IGF1R protein levels without affecting IR. CryoEM analysis confirms that scMFRV-VILP' binding to IGF1R is mirroring the interaction pattern observed with IGF-1. These findings offer valuable insights into IGF1R action and inhibition, suggesting potential applications in development of IGF1R specific inhibitors and advancing long-lasting insulins.
- MeSH
- elektronová kryomikroskopie MeSH
- exprese genu MeSH
- fosfatidylinositol-3-kinasy metabolismus MeSH
- fosforylace MeSH
- insulinu podobný růstový faktor I * genetika metabolismus MeSH
- inzulin metabolismus MeSH
- lidé MeSH
- myši MeSH
- protein - isoformy metabolismus MeSH
- protoonkogenní proteiny c-akt metabolismus MeSH
- receptor IGF typ 1 * genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Insulin-like Growth Factor-2 (IGF2) is important for the regulation of human embryonic growth and development, and for adults' physiology. Incorrect processing of the IGF2 precursor, pro-IGF2(156), leads to the formation of two IGF2 proforms, big-IGF2(87) and big-IGF2(104). Unprocessed and mainly non-glycosylated IGF2 proforms are found at abnormally high levels in certain diseases, but their mode of action is still unclear. Here, we found that pro-IGF2(156) has the lowest ability to form its inactivating complexes with IGF-Binding Proteins and has higher proliferative properties in cells than IGF2 and other IGF prohormones. We also showed that big-IGF2(104) has a seven-fold higher binding affinity for the IGF2 receptor than IGF2, and that pro-IGF2(87) binds and activates specific receptors and stimulates cell growth similarly to the mature IGF2. The properties of these pro-IGF2 forms, especially of pro-IGF2(156) and big-IGF2(104), indicate them as hormones that may be associated with human diseases related to the accumulation of IGF-2 proforms in the circulation.
Elucidating how insulin and the related insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) bind to their cellular receptors (IR and IGF-1R) and how the receptors are activated has been the holy grail for generations of scientists. However, deciphering the 3D structure of tyrosine kinase receptors and their hormone-bound complexes has been complicated by the flexible and dimeric nature of the receptors and the dynamic nature of their interaction with hormones. Therefore, mutagenesis of hormones and kinetic studies first became an important tool for studying receptor interactions. It was suggested that hormones could bind to receptors through two binding sites on the hormone surface called site 1 and site 2. A breakthrough in knowledge came with the solution of cryoelectron microscopy (cryoEM) structures of hormone-receptor complexes. In this chapter, we document in detail the mutagenesis of insulin, IGF-1, and IGF-2 with emphasis on modifications of the hypothetical binding site 2 in the hormones, and we discuss the results of structure-activity studies in light of recent cryoEM structures of hormone complexes with IR and IGF-1R.
Cukrovka je vážné metabolické onemocnění způsobené neschopností těla produkovat inzulin či na něj citlivě reagovat. Životy miliónů diabetických pacientů jsou zachraňovány díky pravidelné podkožní aplikaci inzulinu. Přes 100 let výzkumu inzulinu stále ještě není optimalizováno jeho podání pacientům, které se liší od fyziologického působení, kdy je inzulin sekretován ze slinivky nejprve do jater, kde plní důležité fyziologické funkce, a až pak do periferie organismu. Opožděné působení inzulinu v játrech po podkožním podání způsobuje nerovnováhy v glykémii pacientů a tím i zdravotní komplikace. V této práci shrnujeme výsledky dosažené při vývoji derivátů inzulinu s preferenčním působením v játrech a diskutujeme jejich potenciál pro léčbu cukrovky
Diabetes mellitus is a serious metabolic disease caused by the inability of the body to produce or respond to insulin. The lives of millions of diabetic patients are saved by regular subcutaneous administration of insulin. Despite 100 years of research on insulin, its administ‐ ration to patients is still not optimized because it differs from the physiological action, where insulin is secreted from the pancreas first to the liver, where it performs important physiological functions, and then to the periphery of the body. The delayed action of insulin in the liver after subcutaneous administration causes imbalances in patients’ glycaemia and thus health complications. In this paper, we summarize the results obtained in the development of insulin derivatives with preferential action in the liver and discuss their potential for the treatment of diabetes.
- MeSH
- biochemické jevy MeSH
- biomedicínský výzkum MeSH
- diabetes mellitus farmakoterapie MeSH
- inzuliny * chemie farmakologie fyziologie MeSH
- játra účinky léků MeSH
- krevní glukóza účinky léků MeSH
- lidé MeSH
- modely u zvířat MeSH
- receptor inzulinu chemie MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Insulin is a peptide responsible for regulating the metabolic homeostasis of the organism; it elicits its effects through binding to the transmembrane insulin receptor (IR). Insulin mimetics with agonistic or antagonistic effects toward the receptor are an exciting field of research and could find applications in treating diabetes or malignant diseases. We prepared five variants of a previously reported 20-amino acid insulin-mimicking peptide. These peptides differ from each other by the structure of the covalent bridge connecting positions 11 and 18. In addition to the peptide with a disulfide bridge, a derivative with a dicarba bridge and three derivatives with a 1,2,3-triazole differing from each other by the presence of sulfur or oxygen in their staples were prepared. The strongest binding to IR was exhibited by the peptide with a disulfide bridge. All other derivatives only weakly bound to IR, and a relationship between increasing bridge length and lower binding affinity can be inferred. Despite their nanomolar affinities, none of the prepared peptide mimetics was able to activate the insulin receptor even at high concentrations, but all mimetics were able to inhibit insulin-induced receptor activation. However, the receptor remained approximately 30% active even at the highest concentration of the agents; thus, the agents behave as partial antagonists. An interesting observation is that these mimetic peptides do not antagonize insulin action in proportion to their binding affinities. The compounds characterized in this study show that it is possible to modulate the functional properties of insulin receptor peptide ligands using disulfide mimetics.
- MeSH
- disulfidy chemie MeSH
- inzulin * metabolismus MeSH
- peptidy chemie MeSH
- receptor inzulinu * MeSH
- Publikační typ
- časopisecké články MeSH
