Muscarinic Control of MIN6 Pancreatic β Cells Is Enhanced by Impaired Amino Acid Signaling

Guerra, Marcy L.; Wauson, Eric M.; McGlynn, Kathleen; Cobb, Melanie H.

doi:10.1074/jbc.m114.565069

Cited by 7 publications

(8 citation statements)

References 36 publications

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“…Pilocarpine Stimulates ERK Phosphorylation in MIN6 Cells with a Bias toward the Src-Mediated Pathway. Like other GPCRs, M3R is known to activate extracellular signal-regulated kinases, ERK1/2 (Luo et al, 2008;Selway et al, 2012;Guerra et al, 2014). Activation of ERK can occur via distinct mechanisms that can involve G protein-and b-arrestin-mediated pathways and result in ERK phosphorylation.…”

Section: Resultsmentioning

confidence: 99%

Teaching an Old Drug New Tricks: Agonism, Antagonism, and Biased Signaling of Pilocarpine through M3 Muscarinic Acetylcholine Receptor

2017

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Pilocarpine is a prototypical drug used to treat glaucoma and dry mouth and is classified as either a full or partial muscarinic agonist. Here, we report several unexpected results pertaining to its interaction with muscarinic M3 receptor (M3R). We found that pilocarpine was 1000 times less potent in stimulating mouse-eye pupil constriction than muscarinic agonists oxotremorin-M (Oxo-M) or carbachol (CCh), although all three ligands have similar values for M3R. In contrast to CCh or Oxo-M, pilocarpine does not induce Ca mobilization via endogenous M3R in human embryonic kidney cell line 293T (HEK293T) or mouse insulinoma (MIN6) cells. Pilocarpine also fails to stimulate insulin secretion and, instead, antagonizes the insulinotropic effect of Oxo-M and CCh-induced Ca upregulation; however, in HEK293T or Chinese hamster ovary-K1 cells overexpressing M3R, pilocarpine induces Ca transients like those recorded with another cognate G protein-coupled muscarinic receptor, M1R. Stimulation of cells overexpressing M1R or M3R with CCh resulted in a similar reduction in phosphatidylinositol 4,5-bisphosphate (PIP2). In contrast to CCh, pilocarpine stimulated PIP2 hydrolysis only in cells overexpressing M1R but not M3R. Moreover, pilocarpine blocked CCh-stimulated PIP2 hydrolysis in M3R-overexpressing cells, thus, it acted as an antagonist. Pilocarpine activates extracellular regulated kinase 1/2 in MIN6 cells. The stimulatory effect on extracellular regulated kinase (ERK1/2) was blocked by the Src family kinase inhibitor PP2, indicating that the action of pilocarpine on endogenous M3R is biased toward -arrestin. Taken together, our findings show that pilocarpine can act as either an agonist or antagonist of M3R, depending on the cell type, expression level, and signaling pathway downstream of this receptor.

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Section: Resultsmentioning

confidence: 99%

Teaching an Old Drug New Tricks: Agonism, Antagonism, and Biased Signaling of Pilocarpine through M3 Muscarinic Acetylcholine Receptor

2017

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“…A study from 1997 indicated that the ERK1/2 signal transduction pathway is not required for GSIS [13]. However, it has been demonstrated that, in MIN6 mouse pancreatic b-cells and primary rat islet b cells, blocking the ERK1/2 signaling pathway can reduce GSIS [14,15]. In this study, we found that IL-1b can inhibit ERK1/2 activation under glucose stimulation in bTC-6 cells, and the effect of inhibition is related to IL-1b concentration.…”

Section: Discussionmentioning

confidence: 99%

The role of interleukin‐1β and extracellular signal‐regulated kinase 1/2 in glucose‐stimulated insulin secretion

Niu

Xia

et al. 2017

The Kaohsiung J of Med Scie

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Glucose-stimulated insulin secretion (GSIS) is one of the important physiological characteristics of islet β cells, and extracellular-regulated protein kinase 1/2 (ERK1/2) is an important member of the mitogen-activated protein kinase family that regulates this process. The inflammatory cytokine interleukin (IL)-1β can inhibit the insulin secretion of pancreatic β cells, but the exact mechanism is unclear. This study was designed to investigate the inhibitory effect of IL-1β on GSIS in βTC-6 cells and its relation with the ERK1/2 signal transduction pathway. β-TC6 cells were cultured and stimulated with 0mM, 1.38mM, or 5.5mM glucose. In addition, GSIS in β-TC6 cells was blocked by IL-1β at concentrations of 0.15 ng/mL, 1.5 ng/mL, and 15 ng/mL. After glucose stimulation and IL-1β intervention, the insulin level in the cell supernatant was detected by radioimmunoassay, and the phosphorylation level of ERK1/2 was detected by western blotting assay. The insulin level in the 1.38mM glucose group was 108.52 ± 5.94 uIU/mL, which was significantly higher than the 0mM and 5.5mM glucose groups (p < 0.05). Compared with the 0mM glucose group, the level of ERK1/2 phosphorylation was increased in the 1.38mM and 5.5mM glucose groups. After intervention by 0.15 ng/mL, 1.5 ng/mL, and 15 ng/mL IL-1β, the level of ERK1/2 phosphorylation induced by 1.38mM glucose stimulation decreased in a dose-dependent manner, and the insulin level correspondingly decreased. IL-1β can inhibit GSIS in βTC-6 cells, which is related to its inhibition of the phosphorylation of ERK1/2.

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“…A study from 1997 indicated that the ERK1/2 signal transduction pathway is not required for glucose-stimulated insulin secretion (15). However, it has been demonstrated that is found that in MIN6 mouse pancreatic β-cells and primary rat islet β cells, blocking of the ERK1/2 signaling pathway reduced glucose-stimulated insulin secretion (14,16). Furthermore, Vlacich et al (17) reported that the protein kinase Pim3 can inhibit the activation of the ERK1/2 signal pathway through suppressor of cytokine-induced signaling 6 and regulates glucose-stimulated insulin secretion.…”

Section: Discussionmentioning

confidence: 99%

Role of extracellular signal-regulated kinase 1/2 signal transduction pathway in insulin secretion by β-TC6 cells

Niu

Liu²,

et al. 2016

Molecular Medicine Reports

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The present study aimed to investigate the role of the extracellular signal-regulated kinase (ERK)1/2 signal transduction pathway in glucose‑stimulated insulin secretion in β‑TC6 mouse pancreatic cells. Insulin production by β‑TC6 cells was stimulated with various concentrations of glucose, which was dose-dependently inhibited by mitogen‑activated protein kinase inhibitor PD98059, as indicated by a radioimmunoassay. Furthermore, glucose stimulation enhanced the phosphorylation of ERK1/2, which was dose-dependently inhibited by PD98059, as indicated by western blot analysis. These results indicated that the activation of the ERK1/2 signal transduction pathway may have an important role in glucose‑stimulated insulin secretion in β‑TC6 cells.

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Muscarinic Control of MIN6 Pancreatic β Cells Is Enhanced by Impaired Amino Acid Signaling

Cited by 7 publications

References 36 publications

Teaching an Old Drug New Tricks: Agonism, Antagonism, and Biased Signaling of Pilocarpine through M3 Muscarinic Acetylcholine Receptor

Teaching an Old Drug New Tricks: Agonism, Antagonism, and Biased Signaling of Pilocarpine through M3 Muscarinic Acetylcholine Receptor

The role of interleukin‐1β and extracellular signal‐regulated kinase 1/2 in glucose‐stimulated insulin secretion

Role of extracellular signal-regulated kinase 1/2 signal transduction pathway in insulin secretion by β-TC6 cells

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