The molecular mechanism of EGF receptor activation in pancreatic β-cells by thyrotropin-releasing hormone

2006 ◽  
Vol 290 (5) ◽  
pp. E889-E899 ◽  
Author(s):  
LuGuang Luo ◽  
Naohiro Yano ◽  
John Z. Q. Luo
Keyword(s):  
Signal Transduction ◽  
Growth Factor ◽  
Cell Line ◽  
Egf Receptor ◽  
Receptor Activation ◽  
Signal Transduction Pathways ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Trh Receptor

Thyrotropin-releasing hormone (TRH) and its receptor subtype TRH receptor-1 (TRHR1) are found in pancreatic β-cells, and it has been shown that TRH might have potential for autocrine/paracrine regulation through the TRHR1 receptor. In this paper, TRHR1 is studied to find whether it can initiate multiple signal transduction pathways to activate the epidermal growth factor (EGF) receptor in pancreatic β-cells. By initiating TRHR1 G protein-coupled receptor (GPCR) and dissociated αβγ-complex, TRH (200 nM) activates tyrosine residues at Tyr845 (a known target for Src) and Tyr1068 in the EGF receptor complex of an immortalized mouse β-cell line, βTC-6. Through manipulating the activation of Src, PKC, and heparin-binding EGF-like growth factor (HB-EGF), with corresponding individual inhibitors and activators, multiple signal transduction pathways linking TRH to EGF receptors in βTC-6 cell line have been revealed. The pathways include the activation of Src kinase and the release of HB-EGF as a consequence of matrix metalloproteinase (MMP)-3 activation. Alternatively, TRH inhibited PKC activity by reducing the EGF receptor serine/threonine phosphorylation, thereby enhancing tyrosine phosphorylation. TRH receptor activation of Src may have a central role in mediating the effects of TRH on the EGF receptor. The activation of the EGF receptor by TRH in multiple circumstances may have important implications for pancreatic β-cell biology.

Hepatocyte Growth Factor and Macrophage-stimulating Protein “Hinge” Analogs to Treat Pancreatic Cancer

2019 ◽  
Vol 19 (10) ◽  
pp. 782-795
Author(s):  
John W. Wright ◽  
Kevin J. Church ◽  
Joseph W. Harding
Keyword(s):  
Pancreatic Cancer ◽  
Signal Transduction ◽  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Tumor Growth ◽  
Receptor Activation ◽  
Signal Transduction Pathways ◽  
Met Receptor ◽  
Macrophage Stimulating Protein ◽  
Hepatocyte Growth

Pancreatic cancer (PC) ranks twelfth in frequency of diagnosis but is the fourth leading cause of cancer related deaths with a 5 year survival rate of less than 7 percent. This poor prognosis occurs because the early stages of PC are often asymptomatic. Over-expression of several growth factors, most notably vascular endothelial growth factor (VEGF), has been implicated in PC resulting in dysfunctional signal transduction pathways and the facilitation of tumor growth, invasion and metastasis. Hepatocyte growth factor (HGF) acts via the Met receptor and has also received research attention with ongoing efforts to develop treatments to block the Met receptor and its signal transduction pathways. Macrophage-stimulating protein (MSP), and its receptor Ron, is also recognized as important in the etiology of PC but is less well studied. Although the angiotensin II (AngII)/AT1 receptor system is best known for mediating blood pressure and body water/electrolyte balance, it also facilitates tumor vascularization and growth by stimulating the expression of VEGF. A metabolite of AngII, angiotensin IV (AngIV) has sequence homology with the “hinge regions” of HGF and MSP, key structures in the growth factor dimerization processes necessary for Met and Ron receptor activation. We have developed AngIV-based analogs designed to block dimerization of HGF and MSP and thus receptor activation. Norleual has shown promise as tested utilizing PC cell cultures. Results indicate that cell migration, invasion, and pro-survival functions were suppressed by this analog and tumor growth was significantly inhibited in an orthotopic PC mouse model.

scholarly journals CRISPR/Cas9-Mediated α-ENaC Knockout in a Murine Pancreatic β-Cell Line

2021 ◽  
Vol 12 ◽  
Author(s):  
Xue Zhang ◽  
Lihua Zhao ◽  
Runbing Jin ◽  
Min Li ◽  
Mei-Shuang Li ◽  
...  
Keyword(s):  
Cell Line ◽  
Gene Knockout ◽  
Pancreatic Tissue ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Min6 Cells ◽  
Insulin Synthesis ◽  
Guide Rna

Many ion channels participate in controlling insulin synthesis and secretion of pancreatic β-cells. Epithelial sodium channel (ENaC) expressed in human pancreatic tissue, but the biological role of ENaC in pancreatic β-cells is still unclear. Here, we applied the CRISPR/Cas9 gene editing technique to knockout α-ENaC gene in a murine pancreatic β-cell line (MIN6 cell). Four single-guide RNA (sgRNA) sites were designed for the exons of α-ENaC. The sgRNA1 and sgRNA3 with the higher activity were constructed and co-transfected into MIN6 cells. Through processing a series of experiment flow included drug screening, cloning, and sequencing, the α-ENaC gene-knockout (α-ENaC−/−) in MIN6 cells were obtained. Compared with the wild-type MIN6 cells, the cell viability and insulin content were significantly increased in α-ENaC−/− MIN6 cells. Therefore, α-ENaC−/− MIN6 cells generated by CRISPR/Cas9 technology added an effective tool to study the biological function of α-ENaC in pancreatic β-cells.

scholarly journals Endosomal Signaling of Epidermal Growth Factor Receptor Stimulates Signal Transduction Pathways Leading to Cell Survival

2002 ◽  
Vol 22 (20) ◽  
pp. 7279-7290 ◽  
Author(s):  
Yi Wang ◽  
Steven Pennock ◽  
Xinmei Chen ◽  
Zhixiang Wang
Keyword(s):  
Signal Transduction ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Kinase Inhibitor ◽  
Nucleation Site ◽  
Signal Transduction Pathways ◽  
Egfr Signaling ◽  
Endosomal Signaling ◽  
Epidermal Growth

ABSTRACT In spite of intensified efforts to understand cell signaling from endosomes, there is no direct evidence demonstrating that endosomal signaling is sufficient to activate signal transduction pathways and no evidence to demonstrate that endosomal signaling is able to produce a biological outcome. The lack of breakthrough is due in part to the lack of means to generate endosomal signals without plasma membrane signaling. In this paper, we report the establishment of a system to specifically activate epidermal growth factor (EGF) receptor (EGFR) when it endocytoses into endosomes. We treated cells with EGF in the presence of AG-1478, a specific EGFR tyrosine kinase inhibitor, and monensin, which blocks the recycling of EGFR. This treatment led to the internalization of nonactivated EGF-EGFR complexes into endosomes. The endosome-associated EGFR was then activated by removing AG-1478 and monensin. During this procedure we did not observe any surface EGFR phosphorylation. We also achieved specific activation of endosome-associated EGFR without using monensin. By using this system, we provided original evidence demonstrating that (i) the endosome can serve as a nucleation site for the formation of signaling complexes, (ii) endosomal EGFR signaling is sufficient to activate the major signaling pathways leading to cell proliferation and survival, and (iii) endosomal EGFR signaling is sufficient to suppress apoptosis induced by serum withdrawal.

Regulation of cAMP dynamics by Ca2+ and G protein-coupled receptors in the pancreatic β-cell: a computational approach

2007 ◽  
Vol 293 (6) ◽  
pp. C1924-C1933 ◽  
Author(s):  
Leonid E. Fridlyand ◽  
Mark C. Harbeck ◽  
Michael W. Roe ◽  
Louis H. Philipson
Keyword(s):  
Membrane Potential ◽  
G Protein ◽  
Low Frequency ◽  
Receptor Activation ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Calcium Indicator ◽  
Insulinoma Cells ◽  
G Protein Coupled

In this report we describe a mathematical model for the regulation of cAMP dynamics in pancreatic β-cells. Incretin hormones such as glucagon-like peptide 1 (GLP-1) increase cAMP and augment insulin secretion in pancreatic β-cells. Imaging experiments performed in MIN6 insulinoma cells expressing a genetically encoded cAMP biosensor and loaded with fura-2, a calcium indicator, showed that cAMP oscillations are differentially regulated by periodic changes in membrane potential and GLP-1. We modeled the interplay of intracellular calcium (Ca2+) and its interaction with calmodulin, G protein-coupled receptor activation, adenylyl cyclases (AC), and phosphodiesterases (PDE). Simulations with the model demonstrate that cAMP oscillations are coupled to cytoplasmic Ca2+ oscillations in the β-cell. Slow Ca2+ oscillations (<1 min−1) produce low-frequency cAMP oscillations, and faster Ca2+ oscillations (>3–4 min−1) entrain high-frequency, low-amplitude cAMP oscillations. The model predicts that GLP-1 receptor agonists induce cAMP oscillations in phase with cytoplasmic Ca2+ oscillations. In contrast, observed antiphasic Ca2+ and cAMP oscillations can be simulated following combined glucose and tetraethylammonium-induced changes in membrane potential. The model provides additional evidence for a pivotal role for Ca2+-dependent AC and PDE activation in coupling of Ca2+ and cAMP signals. Our results reveal important differences in the effects of glucose/TEA and GLP-1 on cAMP dynamics in MIN6 β-cells.

GLP-1(28–36) improves β-cell mass and glucose disposal in streptozotocin-induced diabetic mice and activates cAMP/PKA/β-catenin signaling in β-cells in vitro

2013 ◽  
Vol 304 (12) ◽  
pp. E1263-E1272 ◽  
Author(s):  
Weijuan Shao ◽  
Zhaoxia Wang ◽  
Wilfred Ip ◽  
Yu-Ting Chiang ◽  
Xiaoquan Xiong ◽  
...  
Keyword(s):  
Cyclin D1 ◽  
Cell Line ◽  
Cell Mass ◽  
Glucose Disposal ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
In Vitro Investigation

Recent studies have demonstrated that the COOH-terminal fragment of the incretin hormone glucagon-like peptide-1 (GLP-1), a nonapeptide GLP-1(28–36)amide, attenuates diabetes and hepatic steatosis in diet-induced obese mice. However, the effect of this nonapeptide in pancreatic β-cells remains largely unknown. Here, we show that in a streptozotocin-induced mouse diabetes model, GLP-1(28–36)amide improved glucose disposal and increased pancreatic β-cell mass and β-cell proliferation. An in vitro investigation revealed that GLP-1(28–36)amide stimulates β-catenin (β-cat) Ser675 phosphorylation in both the clonal INS-1 cell line and rat primary pancreatic islet cells. In INS-1 cells, the stimulation was accompanied by increased nuclear β-cat content. GLP-1(28–36)amide was also shown to increase cellular cAMP levels, PKA enzymatic activity, and cAMP response element-binding protein (CREB) and cyclic AMP-dependent transcription factor-1 (ATF-1) phosphorylation. Furthermore, GLP-1(28–36)amide treatment enhanced islet insulin secretion and increased the growth of INS-1 cells, which was associated with increased cyclin D1 expression. Finally, PKA inhibition attenuated the effect of GLP-1(28–36)amide on β-cat Ser675 phosphorylation and cyclin D1 expression in the INS-1 cell line. We have thus revealed the beneficial effect of GLP-1(28–36)amide in pancreatic β-cells in vitro and in vivo. Our observations suggest that GLP-1(28–36)amide may exert its effect through the PKA/β-catenin signaling pathway.

scholarly journals Visfatin regulates insulin secretion, insulin receptor signalling and mRNA expression of diabetes-related genes in mouse pancreatic β-cells

2009 ◽  
Vol 44 (3) ◽  
pp. 171-178 ◽  
Author(s):  
James E P Brown ◽  
David J Onyango ◽  
Manjunath Ramanjaneya ◽  
Alex C Conner ◽  
Snehal T Patel ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Receptor ◽  
Mrna Expression ◽  
Fold Increase ◽  
Receptor Activation ◽  
Nuclear Factor ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Nicotinamide Phosphoribosyltransferase

The role of the adipocyte-derived factor visfatin in metabolism remains controversial, although some pancreatic β-cell-specific effects have been reported. This study investigated the effects of visfatin upon insulin secretion, insulin receptor activation and mRNA expression of key diabetes-related genes in clonal mouse pancreatic β-cells. β-TC6 cells were cultured in RPMI 1640 and were subsequently treated with recombinant visfatin. One-hour static insulin secretion was measured by ELISA. Phospho-specific ELISA and western blotting were used to detect insulin receptor activation. Real-time SYBR Green PCR array technology was used to measure the expression of 84 diabetes-related genes in both treatment and control cells. Incubation with visfatin caused significant changes in the mRNA expression of several key diabetes-related genes, including marked up-regulation of insulin (9-fold increase), hepatocyte nuclear factor (HNF)1β (32-fold increase), HNF4α (16-fold increase) and nuclear factor κB (40-fold increase). Significant down-regulation was seen in angiotensin-converting enzyme (−3.73-fold) and UCP2 (−1.3-fold). Visfatin also caused a significant 46% increase in insulin secretion compared to control (P<0.003) at low glucose, and this increase was blocked by co-incubation with the specific nicotinamide phosphoribosyltransferase inhibitor FK866. Both visfatin and nicotinamide mononucleotide induced activation of both insulin receptor and extracellular signal-regulated kinase (ERK)1/2, with visfatin-induced insulin receptor/ERK1/2 activation being inhibited by FK866. We conclude that visfatin can significantly regulate insulin secretion, insulin receptor phosphorylation and intracellular signalling and the expression of a number of β-cell function-associated genes in mouse β-cells.

Protective functions of peroxiredoxin-1 against cytokine-induced MIN6 pancreatic β-cell line death

2013 ◽  
Vol 91 (12) ◽  
pp. 1037-1043 ◽  
Author(s):  
Yun-Jung Lee ◽  
Dong Sup Song ◽  
Jong-Sun Yoo ◽  
Kyeong Eun Hyung ◽  
Mi Ji Lee ◽  
...  
Keyword(s):  
Antioxidant Enzyme ◽  
Cell Line ◽  
Nuclear Translocation ◽  
Inos Expression ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Min6 Cells ◽  
Apoptotic Gene

Pancreatic β-cells play a crucial role in glucose homeostasis, and the failure of these cells to function results in the development of type 1 diabetes (T1D). The MIN6 cell line, which closely resembles pancreatic β-cells, was used to unravel the relationship between pancreatic β-cell function and the antioxidant enzyme PRX-1. PRX-1 was knocked down in MIN6 cells using a shPRX-1 lentiviral construct, and a mixture of inflammatory cytokines was administered to challenge the MIN6 cells. Nitric oxide (NO) production and inducible NO synthase (iNOS) expression were elevated in shPRX-1 compared with the control. Also, shPRX-1 transduced cells showed higher levels of NF-κB nuclear translocation, suggesting that PRX-1 has a regulatory role in NF-κB nuclear translocation and iNOS expression. In correlation with NO levels, decreased anti-apoptotic gene Bcl-xl level and elevated pro-apoptotic gene Bim levels were observed in shPRX-1 cells compared with scramble, and cell viability decreased accordingly. A rescue experiment was performed subsequently using an iNOS inhibitor to confirm NO as the cause of cell death. Overall, the results of this study suggest possible protective roles of the antioxidant enzyme PRX-1 in the insulinoma cell line MIN6 and possibly in pancreatic β-cells under T1D conditions.

scholarly journals Stimulation of pancreatic β-cell proliferation by growth hormone is glucose-dependent: signal transduction via Janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) with no crosstalk to insulin receptor substrate-mediated mitogenic signalling

1999 ◽  
Vol 344 (3) ◽  
pp. 649-658 ◽  
Author(s):  
Sharon P. COUSIN ◽  
Sigrun R. HülGL ◽  
JR. Martin G. MYERS ◽  
Morris F. WHITE ◽  
Anne REIFEL-MILLER ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Growth Hormone ◽  
Cell Proliferation ◽  
Janus Kinase ◽  
Signal Transduction Pathways ◽  
Insulin Receptor Substrate ◽  
Signal Transducer ◽  
Β Cells ◽  
Β Cell ◽  
Mitogenic Signalling

Mitogenic signal-transduction pathways have not been well defined in pancreatic β-cells. In the glucose-sensitive rat β-cell line, INS-1, glucose (6-18 mM) increased INS-1 cell proliferation (> 20-fold at 15 mM glucose). Rat growth hormone (rGH) also induced INS-1 cell proliferation, but this was glucose-dependent in the physiologically relevant concentration range (6-18 mM glucose). The combination of rGH (10 nM) and glucose (15 mM) was synergistic, maximally increasing INS-1 cell proliferation by > 50-fold. Moreover, glucose-dependent rGH-induced INS-1 cell proliferation was increased further by addition of insulin-like growth factor 1 (IGF-1; 10 nM) to > 90-fold at 12 mM glucose. Glucose metabolism and phosphatidylinositol-3ʹ-kinase (PI3ʹK) activation were necessary for both glucose- and rGH-stimulated INS-1 cell proliferation. Glucose (> 3 mM) independently increased tyrosine-phosphorylation-mediated recruitment of growth-factor-bound protein 2 (Grb2)/murine sons of sevenless-1 protein (mSOS) and PI3ʹK to insulin receptor substrate (IRS)-1 and IRS-2, as well as SH2-containing protein (Shc) association with Grb2/mSOS and downstream activation of mitogen-activated protein kinase and 70 kDa S6 kinase. Glucose-induced IRS- and Shc-mediated signal transduction was enhanced further by the addition of IGF-1, but not rGH. In contrast, rGH was able to activate Janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) signal transduction at glucose concentrations above 3 mM, but neither glucose independently, nor glucose with added IGF-1, were able to activate the JAK2/STAT5 signalling pathway. Thus rGH-mediated proliferation of β-cells is directly via the JAK2/STAT5 pathway without engaging the Shc or IRS signal-transduction pathways, although activation of PI3ʹK may play an important permissive role in the glucose-dependent aspect of rGH-induced β-cell mitogensis. The additive effect of rGH and IGF-1 on glucose-dependent β-cell proliferation is therefore reflective of rGH and IGF-1 activating distinctly different mitogenic signalling pathways in β-cells with minimal crosstalk between them.

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