Glucagon.com

GLUTag cells are a stable immortalized murine enteroendocrine cell line that express the glucagon gene and secretes the glucagon-like peptides in a regulated manner

This cell line was isolated from a glucagon-producing enteroendocrine cell tumor that arose in glucagon gene-SV40 T antigen transgenic mice Glucagon gene 5'-flanking sequences direct expression of simian virus 40 large T antigen to the intestine, producing carcinoma of the large bowel in transgenic mice. J Biol Chem. 1992 May 25;267 (15): 10705-8

GLUTag cells have been serially passaged in nude mice, and give rise to glucagonomas that exhibit a stable phenotype of glucagon gene expression over a 4-8 week period as shown in Inhibition of pancreatic glucagon gene expression in mice bearing a subcutaneous glucagon-producing GLUTag transplantable tumor. Mol Endocrinol. 1992 Dec;6(12):2175-84.

In contrast to mouse STC-1 cells, GLUTag cells appear quite well differentiated, and recapitulate the responsiveness of primary non-transformed rat intestinal cell cultures to physiological and pharmacological secretagogues as demonstrated in Activation of proglucagon gene transcription by protein kinase-A in a novel mouse enteroendocrine cell line. Mol Endocrinol. 1994 Dec;8(12):1646-55 and Regulation of glucagon-like peptide-1 synthesis and secretion in the GLUTag enteroendocrine cell line. Endocrinology. 1998 Oct;139(10):4108-14.

Gribble and colleagues used a transgenic approach to isolate non-transformed L cells using a fluorescent protein expressed in L cells under the control of the proglucagon promoter. Isolated sorted GLP-1-secreting L cells were analyzed in primary culture. These cells were directly glucose-responsive, and secreted GLP-1 in response to agents causing membrane depolarization or neurotransmitter-stimulated signal transduction. Moreover, comparison of key genes and proteins expressed in and signal transduction pathways operative in L cells with the same genes, proteins, and pathways utilized by the GLUTag cell line revealed remarkable similarities between non-immortalized L cells and GLUTag cells. Remarkably, primary mouse L cell cultures and GLUTag cells exhibit a similar Ec50 for glucose stimulation of GLP-1 secretion, comparable responsivity to forskolin/IBMX and bomesin and very similar patterns of gene expression profiles for key receptors, glucose sensorss, ion channels, and regulatory molecules (Figure 4 and Table S1); See Glucose sensing in L cells: a primary cell study Cell Metab. 2008 Dec;8(6):532-9

GLUTag cells have been utilized extensively for the analysis of GLP-1/GLP-2 secretagogues, and for studies of enteroendocrine glucagon gene transcription.

GLUTag cells have also been studied for analysis of CCK biosynthesis and secretion.

GLUTag cells have been propagated intermittently since 1991 in the Drucker lab, and early passage cells have retained their differentiated phenotype both in vitro and in vivo. Indeed, independent studies carried out over a decade later reveal preserved glucose competence, with GLP-1 secretion stimulated over a range of glucose concentrations, likely via closure of KATP channels, as shown in Glucose-sensing in glucagon-like Peptide-1-secreting cells. Diabetes. 2002 Sep;51(9):2757-63.

Furthermore, GLUTag cells control GLP-1 secretion in part through depolarization events triggered not only by metabolizable sugars (glucose or fructose) but also by through non-metabolizable sugars through a SGLT-dependent mechanism, as outlined in A Novel Glucose-Sensing Mechanism Contributing to Glucagon-Like Peptide-1 Secretion From the GLUTag Cell Line. Diabetes. 2003 May;52(5):1147-54

Moreover, glutamine has also been shown to be a potent secretagogue in GLP-1 release as outlined in Glutamine potently stimulates glucagon-like peptide-1 secretion from GLUTag cells. Diabetologia. 2004 Sep;47(9):1592-601. Epub 2004 Sep

Similarly, Reimann, Gribble and colleagues have characterized ion channel current and channel expression in GLUTag cells. These studies demonstrated that GLP-1 release in GLUTag cells is not dependent on the firing of Na(+)-carrying action potentials but requires membrane depolarisation and Ca(2+) entry through L-type Ca(2+) channels. See Characterisation and functional role of voltage gated cation conductances in the Glucagon-like peptide-1 secreting GLUTag cell line. J Physiol. 2004 Dec 20; [Epub ahead of print]

Analysis of GLP-1 secretion in GLUTag cells indicates that peptides or pharmacological agents that increase cyclic AMP also increase levels of intracellular calcium, events coupled to stimulation of GLP-1 secretion in GLUTag cells. Enhanced levels of cyclic AMP appear to sensitize the L cells to nutrient-related secretagogues such as glucose See Cyclic AMP triggers glucagon-like peptide-1 secretion from the GLUTag enteroendocrine cell line. Diabetologia. 2007 Jul 21; [Epub ahead of print]

To review some of the GLUTag cell literature, See:

Inhibition of pancreatic glucagon gene expression in mice bearing a subcutaneous glucagon-producing GLUTag transplantable tumor. Mol Endocrinol. 1992 Dec;6(12):2175-84.

Molecular pathophysiology of glucagon-SV40 T antigen transgenic mice. Am J Physiol. 1994 Nov;267(5 Pt 1):E629-35. Review.

Activation of proglucagon gene transcription by protein kinase-A in a novel mouse enteroendocrine cell line. Mol Endocrinol. 1994 Dec;8(12):1646-55

The proglucagon gene upstream enhancer contains positive and negative domains important for tissue-specific proglucagon gene transcription. Mol Endocrinol. 1995 Oct;9(10):1306-20.

The caudal homeobox protein cdx-2/3 activates endogenous proglucagon gene expression in InR1-G9 islet cells. Mol Endocrinol. 1997 Feb;11(2):203-9.

Peptones stimulate cholecystokinin secretion and gene transcription in the intestinal cell line STC-1. Endocrinology. 1997 Mar;138(3):1137-44.

Expression of SNARE proteins in enteroendocrine cell lines and functional role of tetanus toxin-sensitive proteins in cholecystokinin release. FEBS Lett. 1998 Mar 20;425(1):66-70.

Peptones stimulate both the secretion of the incretin hormone glucagon-like peptide 1 and the transcription of the proglucagon gene. Diabetes. 1998 Jul;47(7):1038-45

Regulation of glucagon-like peptide-1 synthesis and secretion in the GLUTag enteroendocrine cell line. Endocrinology. 1998 Oct;139(10):4108-14

Divergent regulation of human and rat proglucagon gene promoters in vivo. Am J Physiol. 1999 Oct;277(4 Pt 1):G829-37

Fatty acid-induced cholecystokinin secretion and changes in intracellular Ca2+ in two enteroendocrine cell lines, STC-1 and GLUTag. J Physiol. 2000 Oct 1;528 Pt 1:165-76