Microtubules Negatively Regulate Insulin Secretion in Pancreatic β Cells

Zhu, Xiaodong; Hu, Ruofei; Briššová, Marcela; Stein, Roland; Powers, Alvin C.; Gu, Guoqiang; Kaverina, Irina

doi:10.1016/j.devcel.2015.08.020

Cited by 95 publications

(206 citation statements)

References 51 publications

(87 reference statements)

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“…In β-cells, the barrier function of the cytoskeleton has been proposed to be critical for maintaining low levels of insulin release under basal conditions (Kalwat and Thurmond, 2013). Importantly, a dense cytoskeletal meshwork at the cell periphery presents a layer of regulation for controlled insulin release under elevated glucose (Zhu et al, 2015). Each individual β-cell contains approximately 10,000 secretory granules of insulin but only a fraction (several hundreds) are released at a time in response to high glucose, emphasizing the precise regulation of release probability of insulin granules (Rorsman and Renstrom, 2003).…”

Section: Discussionmentioning

confidence: 99%

Neurotrophin Signaling Is Required for Glucose-Induced Insulin Secretion

et al. 2016

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Summary Insulin secretion by pancreatic islet β-cells is critical for glucose homeostasis, and a blunted β-cell secretory response is an early deficit in type 2 diabetes. Here, we uncover a regulatory mechanism by which glucose recruits vascular-derived neurotrophins to control insulin secretion. Nerve Growth Factor (NGF), a classical trophic factor for nerve cells, is expressed in pancreatic vasculature while its TrkA receptor is localized to islet β-cells. High glucose rapidly enhances NGF secretion, and increases TrkA phosphorylation in mouse and human islets. Tissue-specific deletion of NGF, TrkA, or acute disruption of TrkA signaling impairs glucose tolerance and insulin secretion in mice. We show that internalized TrkA receptors promote insulin granule exocytosis via F-actin reorganization. Furthermore, NGF treatment augments glucose-induced insulin secretion in human islets. These findings reveal a non-neuronal role for neurotrophins, and identify a new regulatory pathway in insulin secretion that can be targeted to ameliorate β-cell dysfunction.

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Section: Discussionmentioning

confidence: 99%

Neurotrophin Signaling Is Required for Glucose-Induced Insulin Secretion

et al. 2016

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“…For all experiments a triple reporter mouse strain ProGlucagon - Venus /RIP- Cherry / Per2 : Luciferase ( ProGcg - Venus /RIP- Cherry / Per2 : Luc ) was derived by crossing the ProGlucagon - Venus(ProGcg-Venus) reporter mouse (23) with Rat Insulin2 promoter (RIP)- Cherry (RIP- Cherry ) (24) and Period2:Luciferase ( Per2:Luc ) mice (25). ProGcg-Venus and RIP-Cherry reporters exhibit a high specificity for α- and β-cells, respectively, while the fusion protein PER2:Luciferase, encoded by Per2:Luc , is a circadian reporter functionally indistinguishable from the wild-type PER2 protein.…”

Section: Methodsmentioning

confidence: 99%

High-Resolution Recording of the Circadian Oscillator in Primary Mouse α- and β-Cell Culture

2017

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Circadian clocks have been developed in evolution as an anticipatory mechanism allowing for adaptation to the constantly changing light environment due to rotation of the Earth. This mechanism is functional in all light-sensitive organisms. There is a considerable body of evidence on the tight connection between the circadian clock and most aspects of physiology and metabolism. Clocks, operative in the pancreatic islets, have caught particular attention in the last years due to recent reports on their critical roles in regulation of insulin secretion and etiology of type 2 diabetes. While β-cell clocks have been extensively studied during the last years, α-cell clocks and their role in islet function and orchestration of glucose metabolism stayed unexplored, largely due to the difficulty to isolate α-cells, which represents a considerable technical challenge. Here, we provide a detailed description of an experimental approach for the isolation of separate mouse α- and β-cell population, culture of isolated primary α- and β-cells, and their subsequent long-term high-resolution circadian bioluminescence recording. For this purpose, a triple reporter ProGlucagon-Venus/RIP-Cherry/Per2:Luciferase mouse line was established, carrying specific fluorescent reporters for α- and β-cells, and luciferase reporter for monitoring the molecular clockwork. Flow cytometry fluorescence-activated cell sorting allowed separating pure α- and β-cell populations from isolated islets. Experimental conditions, developed by us for the culture of functional primary mouse α- and β-cells for at least 10 days, will be highlighted. Importantly, temporal analysis of freshly isolated α- and β-cells around-the-clock revealed preserved rhythmicity of core clock genes expression. Finally, we describe the setting to assess circadian rhythm in cultured α- and β-cells synchronized in vitro. The here-described methodology allows to analyze the functional properties of primary α- and β-cells under physiological or pathophysiological conditions and to assess the islet cellular clock properties.

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“…ProGcg-Venus and RIP-Cherry reporters exhibited very high specificity and expression levels in α and β cells, respectively (Supplemental Fig. S1; Zhu et al 2015;Dusaulcy et al 2016). Bmal1 knockout mice have been described previously by Jouffe et al (2013).…”

Section: Animal Care and Reporter Mouse Strainmentioning

confidence: 99%

“…To analyze the α-cell and β-cell transcriptome and function in parallel, we combined the proglucagon (Gcg)-Venus reporter mouse (Reimann et al 2008) with the β-cell-specific rat insulin2 promoter (RIP)-Cherry reporter mouse for specific labeling of α cells (Zhu et al 2015) and with the Period2::Luciferase (Per2::Luc) knock-in mouse (Yoo et al 2004) for assessment of circadian clock properties (Supplemental Fig. S1).…”

Section: Rna-seq Analysis Reveals Distinct Expression Patterns In α Amentioning

confidence: 99%

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Pancreatic α- and β-cellular clocks have distinct molecular properties and impact on islet hormone secretion and gene expression

et al. 2017

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A critical role of circadian oscillators in orchestrating insulin secretion and islet gene transcription has been demonstrated recently. However, these studies focused on whole islets and did not explore the interplay between α-cell and β-cell clocks. We performed a parallel analysis of the molecular properties of α-cell and β-cell oscillators using a mouse model expressing three reporter genes: one labeling α cells, one specific for β cells, and a third monitoring circadian gene expression. Thus, phase entrainment properties, gene expression, and functional outputs of the α-cell and β-cell clockworks could be assessed in vivo and in vitro at the population and single-cell level. These experiments showed that α-cellular and β-cellular clocks are oscillating with distinct phases in vivo and in vitro. Diurnal transcriptome analysis in separated α and β cells revealed that a high number of genes with key roles in islet physiology, including regulators of glucose sensing and hormone secretion, are differentially expressed in these cell types. Moreover, temporal insulin and glucagon secretion exhibited distinct oscillatory profiles both in vivo and in vitro. Altogether, our data indicate that differential entrainment characteristics of circadian α-cell and β-cell clocks are an important feature in the temporal coordination of endocrine function and gene expression.

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Microtubules Negatively Regulate Insulin Secretion in Pancreatic β Cells

Cited by 95 publications

References 51 publications

Neurotrophin Signaling Is Required for Glucose-Induced Insulin Secretion

Neurotrophin Signaling Is Required for Glucose-Induced Insulin Secretion

High-Resolution Recording of the Circadian Oscillator in Primary Mouse α- and β-Cell Culture

Pancreatic α- and β-cellular clocks have distinct molecular properties and impact on islet hormone secretion and gene expression

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