5u8q

Structural highlights

Disease

[IGF1R_HUMAN] Defects in IGF1R are a cause of insulin-like growth factor 1 resistance (IGF1RES) [MIM:270450]. It is a disorder characterized by intrauterine growth retardation and poor postnatal growth accompanied with increased plasma IGF1.^{[1] [2]} [IGF1_HUMAN] Defects in IGF1 are the cause of insulin-like growth factor I deficiency (IGF1 deficiency) [MIM:608747]. IGF1 deficiency is an autosomal recessive disorder characterized by growth retardation, sensorineural deafness and mental retardation.

Function

[IGF1R_HUMAN] Receptor tyrosine kinase which mediates actions of insulin-like growth factor 1 (IGF1). Binds IGF1 with high affinity and IGF2 and insulin (INS) with a lower affinity. The activated IGF1R is involved in cell growth and survival control. IGF1R is crucial for tumor transformation and survival of malignant cell. Ligand binding activates the receptor kinase, leading to receptor autophosphorylation, and tyrosines phosphorylation of multiple substrates, that function as signaling adapter proteins including, the insulin-receptor substrates (IRS1/2), Shc and 14-3-3 proteins. Phosphorylation of IRSs proteins lead to the activation of two main signaling pathways: the PI3K-AKT/PKB pathway and the Ras-MAPK pathway. The result of activating the MAPK pathway is increased cellular proliferation, whereas activating the PI3K pathway inhibits apoptosis and stimulates protein synthesis. Phosphorylated IRS1 can activate the 85 kDa regulatory subunit of PI3K (PIK3R1), leading to activation of several downstream substrates, including protein AKT/PKB. AKT phosphorylation, in turn, enhances protein synthesis through mTOR activation and triggers the antiapoptotic effects of IGFIR through phosphorylation and inactivation of BAD. In parallel to PI3K-driven signaling, recruitment of Grb2/SOS by phosphorylated IRS1 or Shc leads to recruitment of Ras and activation of the ras-MAPK pathway. In addition to these two main signaling pathways IGF1R signals also through the Janus kinase/signal transducer and activator of transcription pathway (JAK/STAT). Phosphorylation of JAK proteins can lead to phosphorylation/activation of signal transducers and activators of transcription (STAT) proteins. In particular activation of STAT3, may be essential for the transforming activity of IGF1R. The JAK/STAT pathway activates gene transcription and may be responsible for the transforming activity. JNK kinases can also be activated by the IGF1R. IGF1 exerts inhibiting activities on JNK activation via phosphorylation and inhibition of MAP3K5/ASK1, which is able to directly associate with the IGF1R.^{[3] [4] [5] [6] [7] [8] [9] [10] [11]} When present in a hybrid receptor with INSR, binds IGF1. PubMed:12138094 shows that hybrid receptors composed of IGF1R and INSR isoform Long are activated with a high affinity by IGF1, with low affinity by IGF2 and not significantly activated by insulin, and that hybrid receptors composed of IGF1R and INSR isoform Short are activated by IGF1, IGF2 and insulin. In contrast, PubMed:16831875 shows that hybrid receptors composed of IGF1R and INSR isoform Long and hybrid receptors composed of IGF1R and INSR isoform Short have similar binding characteristics, both bind IGF1 and have a low affinity for insulin.^{[12] [13] [14] [15] [16] [17] [18] [19] [20]} [IGF1_HUMAN] The insulin-like growth factors, isolated from plasma, are structurally and functionally related to insulin but have a much higher growth-promoting activity. May be a physiological regulator of [1-14C]-2-deoxy-D-glucose (2DG) transport and glycogen synthesis in osteoblasts. Stimulates glucose transport in rat bone-derived osteoblastic (PyMS) cells and is effective at much lower concentrations than insulin, not only regarding glycogen and DNA synthesis but also with regard to enhancing glucose uptake.^[21]

References

1. ↑ Abuzzahab MJ, Schneider A, Goddard A, Grigorescu F, Lautier C, Keller E, Kiess W, Klammt J, Kratzsch J, Osgood D, Pfaffle R, Raile K, Seidel B, Smith RJ, Chernausek SD. IGF-I receptor mutations resulting in intrauterine and postnatal growth retardation. N Engl J Med. 2003 Dec 4;349(23):2211-22. PMID:14657428 doi:10.1056/NEJMoa010107
2. ↑ Kawashima Y, Kanzaki S, Yang F, Kinoshita T, Hanaki K, Nagaishi J, Ohtsuka Y, Hisatome I, Ninomoya H, Nanba E, Fukushima T, Takahashi S. Mutation at cleavage site of insulin-like growth factor receptor in a short-stature child born with intrauterine growth retardation. J Clin Endocrinol Metab. 2005 Aug;90(8):4679-87. Epub 2005 May 31. PMID:15928254 doi:jc.2004-1947
3. ↑ Kasuya J, Paz IB, Maddux BA, Goldfine ID, Hefta SA, Fujita-Yamaguchi Y. Characterization of human placental insulin-like growth factor-I/insulin hybrid receptors by protein microsequencing and purification. Biochemistry. 1993 Dec 14;32(49):13531-6. PMID:8257688
4. ↑ Tollefsen SE, Stoszek RM, Thompson K. Interaction of the alpha beta dimers of the insulin-like growth factor I receptor is required for receptor autophosphorylation. Biochemistry. 1991 Jan 8;30(1):48-54. PMID:1846292
5. ↑ Soos MA, Field CE, Siddle K. Purified hybrid insulin/insulin-like growth factor-I receptors bind insulin-like growth factor-I, but not insulin, with high affinity. Biochem J. 1993 Mar 1;290 ( Pt 2):419-26. PMID:8452530
6. ↑ Kato H, Faria TN, Stannard B, Roberts CT Jr, LeRoith D. Role of tyrosine kinase activity in signal transduction by the insulin-like growth factor-I (IGF-I) receptor. Characterization of kinase-deficient IGF-I receptors and the action of an IGF-I-mimetic antibody (alpha IR-3). J Biol Chem. 1993 Feb 5;268(4):2655-61. PMID:7679099
7. ↑ Baserga R. The IGF-I receptor in cancer research. Exp Cell Res. 1999 Nov 25;253(1):1-6. PMID:10579905 doi:10.1006/excr.1999.4667
8. ↑ Zong CS, Chan J, Levy DE, Horvath C, Sadowski HB, Wang LH. Mechanism of STAT3 activation by insulin-like growth factor I receptor. J Biol Chem. 2000 May 19;275(20):15099-105. PMID:10747872 doi:10.1074/jbc.M000089200
9. ↑ Pandini G, Frasca F, Mineo R, Sciacca L, Vigneri R, Belfiore A. Insulin/insulin-like growth factor I hybrid receptors have different biological characteristics depending on the insulin receptor isoform involved. J Biol Chem. 2002 Oct 18;277(42):39684-95. Epub 2002 Jul 22. PMID:12138094 doi:10.1074/jbc.M202766200
10. ↑ Galvan V, Logvinova A, Sperandio S, Ichijo H, Bredesen DE. Type 1 insulin-like growth factor receptor (IGF-IR) signaling inhibits apoptosis signal-regulating kinase 1 (ASK1). J Biol Chem. 2003 Apr 11;278(15):13325-32. Epub 2003 Jan 28. PMID:12556535 doi:10.1074/jbc.M211398200
11. ↑ Slaaby R, Schaffer L, Lautrup-Larsen I, Andersen AS, Shaw AC, Mathiasen IS, Brandt J. Hybrid receptors formed by insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) have low insulin and high IGF-1 affinity irrespective of the IR splice variant. J Biol Chem. 2006 Sep 8;281(36):25869-74. Epub 2006 Jul 10. PMID:16831875 doi:10.1074/jbc.M605189200
12. ↑ Kasuya J, Paz IB, Maddux BA, Goldfine ID, Hefta SA, Fujita-Yamaguchi Y. Characterization of human placental insulin-like growth factor-I/insulin hybrid receptors by protein microsequencing and purification. Biochemistry. 1993 Dec 14;32(49):13531-6. PMID:8257688
13. ↑ Tollefsen SE, Stoszek RM, Thompson K. Interaction of the alpha beta dimers of the insulin-like growth factor I receptor is required for receptor autophosphorylation. Biochemistry. 1991 Jan 8;30(1):48-54. PMID:1846292
14. ↑ Soos MA, Field CE, Siddle K. Purified hybrid insulin/insulin-like growth factor-I receptors bind insulin-like growth factor-I, but not insulin, with high affinity. Biochem J. 1993 Mar 1;290 ( Pt 2):419-26. PMID:8452530
15. ↑ Kato H, Faria TN, Stannard B, Roberts CT Jr, LeRoith D. Role of tyrosine kinase activity in signal transduction by the insulin-like growth factor-I (IGF-I) receptor. Characterization of kinase-deficient IGF-I receptors and the action of an IGF-I-mimetic antibody (alpha IR-3). J Biol Chem. 1993 Feb 5;268(4):2655-61. PMID:7679099
16. ↑ Baserga R. The IGF-I receptor in cancer research. Exp Cell Res. 1999 Nov 25;253(1):1-6. PMID:10579905 doi:10.1006/excr.1999.4667
17. ↑ Zong CS, Chan J, Levy DE, Horvath C, Sadowski HB, Wang LH. Mechanism of STAT3 activation by insulin-like growth factor I receptor. J Biol Chem. 2000 May 19;275(20):15099-105. PMID:10747872 doi:10.1074/jbc.M000089200
18. ↑ Pandini G, Frasca F, Mineo R, Sciacca L, Vigneri R, Belfiore A. Insulin/insulin-like growth factor I hybrid receptors have different biological characteristics depending on the insulin receptor isoform involved. J Biol Chem. 2002 Oct 18;277(42):39684-95. Epub 2002 Jul 22. PMID:12138094 doi:10.1074/jbc.M202766200
19. ↑ Galvan V, Logvinova A, Sperandio S, Ichijo H, Bredesen DE. Type 1 insulin-like growth factor receptor (IGF-IR) signaling inhibits apoptosis signal-regulating kinase 1 (ASK1). J Biol Chem. 2003 Apr 11;278(15):13325-32. Epub 2003 Jan 28. PMID:12556535 doi:10.1074/jbc.M211398200
20. ↑ Slaaby R, Schaffer L, Lautrup-Larsen I, Andersen AS, Shaw AC, Mathiasen IS, Brandt J. Hybrid receptors formed by insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) have low insulin and high IGF-1 affinity irrespective of the IR splice variant. J Biol Chem. 2006 Sep 8;281(36):25869-74. Epub 2006 Jul 10. PMID:16831875 doi:10.1074/jbc.M605189200
21. ↑ Zoidis E, Ghirlanda-Keller C, Schmid C. Stimulation of glucose transport in osteoblastic cells by parathyroid hormone and insulin-like growth factor I. Mol Cell Biochem. 2011 Feb;348(1-2):33-42. doi: 10.1007/s11010-010-0634-z. Epub, 2010 Nov 13. PMID:21076856 doi:10.1007/s11010-010-0634-z