Loading Pathway...
Error: Pathway image not found.
Hide
Pathway Description
Incretins - Insulin release Pathway
Homo sapiens
Category:
Metabolite Pathway
Sub-Category:
Physiological
Created: 2023-09-14
Last Updated: 2024-01-20
Endogenous incretins such as such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) are hormones regulating insulin secretion and glucose metabolism in mammals. Incretin acts by stimulating β cells of the pancreas to release more insulin in the blood. GIP is secreted by the enteroendocrine K-cells that are present in high density in the duodenum and upper jejunum but are present throughout the small intestine. Oral ingestion and subsequent absorption of nutrients such as glucose, high amounts of amino acids, and long-chain fatty acids trigger the secretion of GIP.
Glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide (GIP), both incretin hormones inactivated by dipeptidyl peptidase-4 (DPP-4), stimulate insulin secretion after an oral glucose load via the incretin effect. In type 2 diabetes, this process can become blunted or even be absent; however, the utilization of pharmacological levels of GLP-1 can revive insulin excretion. The benefits of this form of therapy to treat type 2 diabetes include delayed gastric emptying and inhibiting the production of glucagon from pancreatic alpha cells if blood sugar levels are high. Furthermore, GLP-1 receptor agonists can decrease pancreatic beta-cell apoptosis while promoting their proliferation.
GIP acts on class-II G-protein coupled receptors. The signaling mechanism for these receptors primarily involves the activation of adenylate cyclase/protein kinase A as well as phospholipase C/protein C cascades. High levels of GIP receptors get expressed in the beta cells of the pancreatic islets. Binding of GIP to its receptor increases the intracellular cAMP levels with a downstream increase in calcium ion concentration and exocytosis of insulin. GIP is rapidly inactivated by the ubiquitous enzyme dipeptidyl peptidase 4 (DPP-4), which is the same enzyme that cleaves GLP-1. However, the inactivation of GIP occurs at a slower rate than GLP-1, giving GIP a half-life of 5 to 7 minutes. DPP-4 cleaves alanine and proline residues in position 2 of the N-terminus in peptide chains. Thus, the substitution of L-alanine for D-alanine residue at position 2 of GIP makes it resistant to the action of DPP-4 and enhances its incretin effect.
Incretins binds to the ATP-sensitive potassium channels on the pancreatic cell surface. This binding causes the reduction of the potassium conductance and, in consequence, the depolarization of the membrane. This depolarization stimulates calcium ion influx through voltage-sensitive calcium channels, raising intracellular concentrations of calcium ions, which results in the secretion (exocytosis) of insulin. These incretins are released in response to food intake and regulate both basal insulin secretion and meal-stimulated insulin release.
References
Incretins - Insulin release Pathway References
Gupta K, Raja A: Physiology, Gastric Inhibitory Peptide.
Pubmed: 31536259
Collins L, Costello RA: Glucagon-Like Peptide-1 Receptor Agonists.
Pubmed: 31855395
Denier C, Ducros A, Durr A, Eymard B, Chassande B, Tournier-Lasserve E: Missense CACNA1A mutation causing episodic ataxia type 2. Arch Neurol. 2001 Feb;58(2):292-5. doi: 10.1001/archneur.58.2.292.
Pubmed: 11176968
Hans M, Urrutia A, Deal C, Brust PF, Stauderman K, Ellis SB, Harpold MM, Johnson EC, Williams ME: Structural elements in domain IV that influence biophysical and pharmacological properties of human alpha1A-containing high-voltage-activated calcium channels. Biophys J. 1999 Mar;76(3):1384-400. doi: 10.1016/S0006-3495(99)77300-5.
Pubmed: 10049321
Ophoff RA, Terwindt GM, Vergouwe MN, van Eijk R, Oefner PJ, Hoffman SM, Lamerdin JE, Mohrenweiser HW, Bulman DE, Ferrari M, Haan J, Lindhout D, van Ommen GJ, Hofker MH, Ferrari MD, Frants RR: Familial hemiplegic migraine and episodic ataxia type-2 are caused by mutations in the Ca2+ channel gene CACNL1A4. Cell. 1996 Nov 1;87(3):543-52. doi: 10.1016/s0092-8674(00)81373-2.
Pubmed: 8898206
Powers PA, Liu S, Hogan K, Gregg RG: Skeletal muscle and brain isoforms of a beta-subunit of human voltage-dependent calcium channels are encoded by a single gene. J Biol Chem. 1992 Nov 15;267(32):22967-72.
Pubmed: 1385409
Williams ME, Feldman DH, McCue AF, Brenner R, Velicelebi G, Ellis SB, Harpold MM: Structure and functional expression of alpha 1, alpha 2, and beta subunits of a novel human neuronal calcium channel subtype. Neuron. 1992 Jan;8(1):71-84. doi: 10.1016/0896-6273(92)90109-q.
Pubmed: 1309651
Collin T, Wang JJ, Nargeot J, Schwartz A: Molecular cloning of three isoforms of the L-type voltage-dependent calcium channel beta subunit from normal human heart. Circ Res. 1993 Jun;72(6):1337-44. doi: 10.1161/01.res.72.6.1337.
Pubmed: 7916667
Klugbauer N, Lacinova L, Marais E, Hobom M, Hofmann F: Molecular diversity of the calcium channel alpha2delta subunit. J Neurosci. 1999 Jan 15;19(2):684-91.
Pubmed: 9880589
Gao B, Sekido Y, Maximov A, Saad M, Forgacs E, Latif F, Wei MH, Lerman M, Lee JH, Perez-Reyes E, Bezprozvanny I, Minna JD: Functional properties of a new voltage-dependent calcium channel alpha(2)delta auxiliary subunit gene (CACNA2D2). J Biol Chem. 2000 Apr 21;275(16):12237-42. doi: 10.1074/jbc.275.16.12237.
Pubmed: 10766861
Hobom M, Dai S, Marais E, Lacinova L, Hofmann F, Klugbauer N: Neuronal distribution and functional characterization of the calcium channel alpha2delta-2 subunit. Eur J Neurosci. 2000 Apr;12(4):1217-26. doi: 10.1046/j.1460-9568.2000.01009.x.
Pubmed: 10762351
Fukumoto H, Seino S, Imura H, Seino Y, Eddy RL, Fukushima Y, Byers MG, Shows TB, Bell GI: Sequence, tissue distribution, and chromosomal localization of mRNA encoding a human glucose transporter-like protein. Proc Natl Acad Sci U S A. 1988 Aug;85(15):5434-8. doi: 10.1073/pnas.85.15.5434.
Pubmed: 3399500
Ota T, Suzuki Y, Nishikawa T, Otsuki T, Sugiyama T, Irie R, Wakamatsu A, Hayashi K, Sato H, Nagai K, Kimura K, Makita H, Sekine M, Obayashi M, Nishi T, Shibahara T, Tanaka T, Ishii S, Yamamoto J, Saito K, Kawai Y, Isono Y, Nakamura Y, Nagahari K, Murakami K, Yasuda T, Iwayanagi T, Wagatsuma M, Shiratori A, Sudo H, Hosoiri T, Kaku Y, Kodaira H, Kondo H, Sugawara M, Takahashi M, Kanda K, Yokoi T, Furuya T, Kikkawa E, Omura Y, Abe K, Kamihara K, Katsuta N, Sato K, Tanikawa M, Yamazaki M, Ninomiya K, Ishibashi T, Yamashita H, Murakawa K, Fujimori K, Tanai H, Kimata M, Watanabe M, Hiraoka S, Chiba Y, Ishida S, Ono Y, Takiguchi S, Watanabe S, Yosida M, Hotuta T, Kusano J, Kanehori K, Takahashi-Fujii A, Hara H, Tanase TO, Nomura Y, Togiya S, Komai F, Hara R, Takeuchi K, Arita M, Imose N, Musashino K, Yuuki H, Oshima A, Sasaki N, Aotsuka S, Yoshikawa Y, Matsunawa H, Ichihara T, Shiohata N, Sano S, Moriya S, Momiyama H, Satoh N, Takami S, Terashima Y, Suzuki O, Nakagawa S, Senoh A, Mizoguchi H, Goto Y, Shimizu F, Wakebe H, Hishigaki H, Watanabe T, Sugiyama A, Takemoto M, Kawakami B, Yamazaki M, Watanabe K, Kumagai A, Itakura S, Fukuzumi Y, Fujimori Y, Komiyama M, Tashiro H, Tanigami A, Fujiwara T, Ono T, Yamada K, Fujii Y, Ozaki K, Hirao M, Ohmori Y, Kawabata A, Hikiji T, Kobatake N, Inagaki H, Ikema Y, Okamoto S, Okitani R, Kawakami T, Noguchi S, Itoh T, Shigeta K, Senba T, Matsumura K, Nakajima Y, Mizuno T, Morinaga M, Sasaki M, Togashi T, Oyama M, Hata H, Watanabe M, Komatsu T, Mizushima-Sugano J, Satoh T, Shirai Y, Takahashi Y, Nakagawa K, Okumura K, Nagase T, Nomura N, Kikuchi H, Masuho Y, Yamashita R, Nakai K, Yada T, Nakamura Y, Ohara O, Isogai T, Sugano S: Complete sequencing and characterization of 21,243 full-length human cDNAs. Nat Genet. 2004 Jan;36(1):40-5. doi: 10.1038/ng1285. Epub 2003 Dec 21.
Pubmed: 14702039
Muzny DM, Scherer SE, Kaul R, Wang J, Yu J, Sudbrak R, Buhay CJ, Chen R, Cree A, Ding Y, Dugan-Rocha S, Gill R, Gunaratne P, Harris RA, Hawes AC, Hernandez J, Hodgson AV, Hume J, Jackson A, Khan ZM, Kovar-Smith C, Lewis LR, Lozado RJ, Metzker ML, Milosavljevic A, Miner GR, Morgan MB, Nazareth LV, Scott G, Sodergren E, Song XZ, Steffen D, Wei S, Wheeler DA, Wright MW, Worley KC, Yuan Y, Zhang Z, Adams CQ, Ansari-Lari MA, Ayele M, Brown MJ, Chen G, Chen Z, Clendenning J, Clerc-Blankenburg KP, Chen R, Chen Z, Davis C, Delgado O, Dinh HH, Dong W, Draper H, Ernst S, Fu G, Gonzalez-Garay ML, Garcia DK, Gillett W, Gu J, Hao B, Haugen E, Havlak P, He X, Hennig S, Hu S, Huang W, Jackson LR, Jacob LS, Kelly SH, Kube M, Levy R, Li Z, Liu B, Liu J, Liu W, Lu J, Maheshwari M, Nguyen BV, Okwuonu GO, Palmeiri A, Pasternak S, Perez LM, Phelps KA, Plopper FJ, Qiang B, Raymond C, Rodriguez R, Saenphimmachak C, Santibanez J, Shen H, Shen Y, Subramanian S, Tabor PE, Verduzco D, Waldron L, Wang J, Wang J, Wang Q, Williams GA, Wong GK, Yao Z, Zhang J, Zhang X, Zhao G, Zhou J, Zhou Y, Nelson D, Lehrach H, Reinhardt R, Naylor SL, Yang H, Olson M, Weinstock G, Gibbs RA: The DNA sequence, annotation and analysis of human chromosome 3. Nature. 2006 Apr 27;440(7088):1194-8. doi: 10.1038/nature04728.
Pubmed: 16641997
Thorens B, Porret A, Buhler L, Deng SP, Morel P, Widmann C: Cloning and functional expression of the human islet GLP-1 receptor. Demonstration that exendin-4 is an agonist and exendin-(9-39) an antagonist of the receptor. Diabetes. 1993 Nov;42(11):1678-82. doi: 10.2337/diab.42.11.1678.
Pubmed: 8405712
Dillon JS, Tanizawa Y, Wheeler MB, Leng XH, Ligon BB, Rabin DU, Yoo-Warren H, Permutt MA, Boyd AE 3rd: Cloning and functional expression of the human glucagon-like peptide-1 (GLP-1) receptor. Endocrinology. 1993 Oct;133(4):1907-10. doi: 10.1210/endo.133.4.8404634.
Pubmed: 8404634
Graziano MP, Hey PJ, Borkowski D, Chicchi GG, Strader CD: Cloning and functional expression of a human glucagon-like peptide-1 receptor. Biochem Biophys Res Commun. 1993 Oct 15;196(1):141-6. doi: 10.1006/bbrc.1993.2226.
Pubmed: 8216285
Jaiswal BS, Conti M: Identification and functional analysis of splice variants of the germ cell soluble adenylyl cyclase. J Biol Chem. 2001 Aug 24;276(34):31698-708. doi: 10.1074/jbc.M011698200. Epub 2001 Jun 21.
Pubmed: 11423534
Reed BY, Gitomer WL, Heller HJ, Hsu MC, Lemke M, Padalino P, Pak CY: Identification and characterization of a gene with base substitutions associated with the absorptive hypercalciuria phenotype and low spinal bone density. J Clin Endocrinol Metab. 2002 Apr;87(4):1476-85. doi: 10.1210/jcem.87.4.8300.
Pubmed: 11932268
Litvin TN, Kamenetsky M, Zarifyan A, Buck J, Levin LR: Kinetic properties of "soluble" adenylyl cyclase. Synergism between calcium and bicarbonate. J Biol Chem. 2003 May 2;278(18):15922-6. doi: 10.1074/jbc.M212475200. Epub 2003 Feb 27.
Pubmed: 12609998
Van Raamsdonk CD, Bezrookove V, Green G, Bauer J, Gaugler L, O'Brien JM, Simpson EM, Barsh GS, Bastian BC: Frequent somatic mutations of GNAQ in uveal melanoma and blue naevi. Nature. 2009 Jan 29;457(7229):599-602. doi: 10.1038/nature07586. Epub 2008 Dec 10.
Pubmed: 19078957
Murali R, Wiesner T, Rosenblum MK, Bastian BC: GNAQ and GNA11 mutations in melanocytomas of the central nervous system. Acta Neuropathol. 2012 Mar;123(3):457-9. doi: 10.1007/s00401-012-0948-x. Epub 2012 Feb 4.
Pubmed: 22307269
Dong Q, Shenker A, Way J, Haddad BR, Lin K, Hughes MR, McBride OW, Spiegel AM, Battey J: Molecular cloning of human G alpha q cDNA and chromosomal localization of the G alpha q gene (GNAQ) and a processed pseudogene. Genomics. 1995 Dec 10;30(3):470-75. doi: 10.1006/geno.1995.1267.
Pubmed: 8825633
Highlighted elements will appear in red.
Highlight Compounds
Highlight Proteins
Enter relative concentration values (without units). Elements will be highlighted in a color gradient where red = lowest concentration and green = highest concentration. For the best results, view the pathway in Black and White.
Visualize Compound Data
Visualize Protein Data
Downloads
Settings