Transglutaminase type 2 (TG2) has been reported to be a candidate gene for maturity onset diabetes of the young (MODY) because three different mutations that impair TG2 transamidase activity have been found in 3 families with MODY. TG2 null (TG2？/？) mice have been reported to be glucose intolerant and have impaired glucose-stimulated insulin secretion (GSIS). Here we rigorously evaluated the role of TG2 in glucose metabolism using independently generated murine models of genetic TG2 disruption, which show no compensatory enhanced expression of other TGs in pancreatic islets or other tissues. First, we subjected chow- or fat-fed congenic SV129 or C57BL/6 wild type (WT) and TG2？/？ littermates, to oral glucose gavage. Blood glucose and serum insulin levels were similar for both genotypes. Pancreatic islets isolated from these animals and analysed in vitro for GSIS and cholinergic potentiation of GSIS, showed no significant difference between genotypes. Results from intraperitoneal glucose tolerance tests (GTTs) and insulin tolerance tests (ITTs) were similar for both genotypes. Second, we directly investigated the role of TG2 transamidase activity in insulin secretion using a coisogenic model that expresses a mutant form of TG2 (TG2R579A), which is constitutively active for transamidase activity. Intraperitoneal GTTs and ITTs revealed no significant differences between WT and TG2R579A/R579A mice. Given that neither deletion nor constitutive activation of TG2 transamidase activity altered basal responses, or responses to a glucose or insulin challenge, our data indicate that glucose homeostasis in mice is TG2 independent, and question a link between TG2 and diabetes.
References
[1]
Ledermann HM (1995) Maturity-onset diabetes of the young (MODY) at least ten times more commin in Europe than previously assumed? Diabetologia 38: 1482.
[2]
Shields BM, Hicks S, Shepherd MH, Colclough K, Hattersley AT, et al. (2010) Maturity-onset diabetes of the young (MODY): how many cases are we missing? Diabetologia 53: 2504–2508.
[3]
Bernassola F, Federici M, Corazzari M, Terrinoni A, Hribal ML, et al. (2002) Role of transglutaminase 2 in glucose tolerance: knockout mice studies and putative mutation in a MODY patient. FASEB J 16: 1371–1378.
[4]
Porzio O, Massa O, Cunsolo V, Colombo C, Malaponti M, et al. (2007) Missense mutations in the TGM2 gene encoding Transglutaminase 2 are found in patients with early-onset Type 2 diabetes. Hum Mutat 28: 1150.
[5]
De Laurenzi V, Melino G (2001) Gene disruption of tissue transglutaminase. Mol Cell Biol 21: 148–155.
[6]
Nanda N, Iismaa SE, Owens WA, Husain A, Mackay F, et al. (2001) Targeted inactivation of Gh/tissue transglutaminase II. J Biol Chem 276: 20673–20678.
[7]
Iismaa SE, Mearns BM, Lorand L, Graham RM (2009) Transglutaminases and disease: Lessons from genetically-engineered mosue models and inherited disorders. Physiol Rev 89: 991–1023.
[8]
Lorand L, Graham RM (2003) Transglutaminases: Crosslinking enzymes with pleiotropic functions. Nat Rev Mol Cell Biol 4: 140–157.
[9]
Achyuthan KE, Greenberg CS (1987) Identification of a guanosine triphosphate-binding site on guinea pig liver transglutaminase. Role of GTP and calcium ions in modulating activity. J Biol Chem 262: 1901–1906.
[10]
Im M-J, Riek RP, Graham RM (1990) A novel guanine nucleotide-binding protein coupled to the α1-adrenergic receptor. II. Purification, characterization, and reconstitution. J Biol Chem 265: 18952–18960.
[11]
Nakaoka H, Perez DM, Baek KJ, Das T, Husain A, et al. (1994) Gh: a GTP-binding protein with transglutaminase activity and receptor signaling function. Science 264: 1593–1596.
[12]
Chen SH, Lin F, Iismaa S, Lee KN, Birckbichler PJ, et al. (1996) α1-adrenergic receptor signaling via Gh is subtype specific and independent of its transglutaminase activity. J Biol Chem 271: 32385–32391.
[13]
Dupuis M, Levy A, Mhaouty-Kodja S (2004) Functional coupling of rat myometrial alpha 1-adrenergic receptors to Gh alpha/tissue transglutaminase 2 during pregnancy. J Biol Chem 279: 19257–19263.
[14]
Vezza R, Habib A, FitzGerald GA (1999) Differential signaling by the thromboxane receptor isoforms via the novel GTP-binding protein, Gh. J Biol Chem 274: 12774–12779.
[15]
Zhang Z, Vezza R, Plappert T, McNamara P, Lawson JA, et al. (2003) COX-2 dependent cardiac failure in Gh/tTG transgenic mice. Circ Res 92: 1153–1161.
[16]
Park ES, Won JH, Han KJ, Suh PG, Ryu SH, et al. (1998) Phospholipase C-delta1 and oxytocin receptor signalling: evidence of its role as an effector. Biochem J 331: 283–289.
[17]
Akimov SS, Krylov D, Fleischmann LF, Belkin AM (2000) Tissue transglutaminase is an integrin-binding adhesion coreceptor for fibronectin. J Cell Biol 148: 825–838.
[18]
Bungay PJ, Potter JM, Griffin M (1984) The inhibition of glucose-stimulated insulin secretion by primary amines. A role for transglutaminase in the secretory mechanism. Biochem J 219: 819–827.
[19]
Paulmann N, Grohmann M, Voigt J-P, Bert B, Vowinckel J, et al. (2009) Intracellular serotonin modulates insulin secretion from pancreatic β-cells by protein serotonylation. PLoS Biol 7: e1000229.
[20]
Gomis R, Sener A, Malaisse-Lagae F, Malaisse WJ (1983) Transglutaminase activity in pancreatic islets. Biochim Biophys Acta 760: 384–388.
[21]
Salter NW, Ande SR, Nyguyen HK, Nyomba BLG, Mishra S (2012) Functional characterization of naturally occurring transglutaminase 2 mutants implicated in early-onset type 2 diabetes. Journal of Molecular Endocrinology 48: 203–216.
[22]
Iismaa TP, Kerr EA, Wilson JR, Carpenter L, Sims N, et al. (2000) Quantitative and functional characterization of muscarinic receptor subtypes in insulin-secreting cell lines and rat pancreatic islets. Diabetes 49: 392–398.
[23]
Gilon P, Henquin J-C (2001) Mechanisms and physiological significance of the cholinergic control of pancreatic β-cell function. Endocr Rev 22: 565–604.
[24]
Duttaroy A, Zimliki CL, Gautam D, Cui Y, Mears D, et al. (2004) Muscarinic stimulation of pancreatic insulin and glucagon release is abolished in M3 muscarinic acetylcholine receptor-deficient mice. Diabetes 53: 1714–1720.
[25]
Schmitz-Peiffer C, Laybutt DR, Burchfield JG, Gurisik E, Narasimhan S, et al. (2007) Inhibition of PKCε improves glucose-stimulated insulin secretion and reduces insulin clearance. Cell Metab 6: 320–328.
[26]
Cantley J, Boslem E, Laybutt DR, Cordery DV, Pearson G, et al. (2011) Deletion of protein kinase Cδ in mice modulates stability of inflammatory genes and protects against cytokine-stimulated beta cell death in vitro and in vivo. Diabetologia 54: 380–389.
[27]
Carpenter L, Mitchell CJ, Xu ZZ, Poronnik P, Both GW, et al. (2004) PKCα is activated but not required during glucose-induced insulin secretion from rat pancreatic islets. Diabetes 53: 53–60.
[28]
Iismaa SE, Wu M-J, Nanda N, Church WB, Graham RM (2000) GTP-binding and signalling by Gh/transglutaminase II involves distinct residues in a unique GTP-binding pocket. J Biol Chem 275: 18259–18265.
[29]
Begg GE, Holman SR, Stokes PH, Matthews JM, Graham RM, et al. (2006) Mutation of a critical GTP-binding arginine in transglutaminase 2 disinhibits intracellular crosslinking activity. J Biol Chem 281: 12603–12609.
[30]
Lee SK, Opara EC, Surwit RS, Feinglos MN, Akwari OE (1995) Defective glucose-stimulated insulin release from perifused islets of C57BL/6J mice. Pancreas 11: 206–211.
[31]
Andrikopoulos S, Massa CM, Aston-Mourney KA, Funkat A, Fam BC, et al. (2005) Differential effect of inbred mouse strain (C57BL/6, DBA/2, 129T2) on insulin secretory function in response to a high fat diet. J Endocrinol 187: 45–53.
[32]
Goren HJ, Kulkarni RN, Kahn CR (2004) Glucose homeostasis and tissue transcript content of insulin signaling intermediates in four inbred strins of mice: C57BL/6, C57BLKS/6, DBA/2 and 129X1. Endocrinology 145: 3307–3323.
[33]
Leiter EH (2002) Mice with targeted gene disruptions or gene insertions for diabetes research: problems, pitfalls, and potential solutions. Diabetologia 45: 296–308.
[34]
Brennan K (2011) Colony Management. In: Pease S, Saunders TL, editors. Advanced protocols for animal transgenesis An ISTT manual. 1st ed. Berlin: Springer-Verlag. 535–576.
[35]
Wong GT (2002) Speed congenics: Applications for transgenic and knock-out mouse strains. Neuropeptides 36: 230–236.
Calkins MJ, Townsend JA, Johnson DA, Johnson JA (2010) Cystamine protects form 3-nitropropionic acid lesioning via induction of nf-e2 related factor 2 mediated transcription. Experimental Neurology 224: 307–317.
[38]
Ruan Q, Johnson GVW (2007) Transglutaminase 2 in neurodegenerative disorders. Front Biosci 12: 891–904.
[39]
Davies PJA, Cornwell MM, Johnson JD, Reggianni A, Myers M, et al. (1984) Studies on the effects of dansylcadaverine and related compounds on receptor-mediated endocytosis in cultured cells. Diabetes Care 7 (Suppl 1)35–41.
