Alterations of the Ca2+ signaling pathway in pancreatic beta-cells isolated from db/db mice

Li, Kuo; Du, Wei; Lu, Jingze; Li, Fēi; Yang, Lu; Xue, Yanhong; Hille, Bertil; Chen, Liangyi

doi:10.1007/s13238-014-0075-7

Cited by 15 publications

(16 citation statements)

References 32 publications

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“…S3B,C). This finding suggests that 10-week-old db/db mice are already in the diabetic stage, which is consistent with previous studies (Do et al, 2014;Liang et al, 2014).…”

Section: Resultssupporting

confidence: 93%

“…In ten-weekold db/db mice, the increase in the α-cell to β-cell function ratio was less than that of the ratio of the α-cell to β-cell mass, which reflects that individual β-cell function was enhanced rather than compromised relative to individual α-cell function. This finding fits with the previous report of insulin hypersecretion from isolated β-cells in 8-week-old db/db mice (Liang et al, 2014). Decreased GSIS from db/db mice is observed only at an even later stage (at 13 to 18 weeks old) (Do et al, 2014), which further leads to hyperglycemia, partially due to the suppression effect of insulin on glucagon secretion being impaired (Unger and Orci, 2010).…”

Section: Discussionsupporting

confidence: 94%

“…Primary islets were isolated from mice as previously described (Liang et al, 2014). After being washed in Krebs-Ringer bicarbonate buffer (KRBB) solution (135 mM NaCl, 4.7 mM KCl, 10 mM HEPES pH 7.4, 3 mM glucose, 1.2 mM KH 2 PO 4 and 5 mM NaHCO 3 ) with 0.1% BSA, the islets were digested with 0.025% trypsin (Life Technologies) for 5 min at 37°C.…”

Section: Isolation Of Mouse Pancreatic Islets and Dissociation Of Islmentioning

confidence: 99%

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An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

Wang

Han

Zhu

et al. 2016

Journal of Cell Science

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Imbalanced glucagon and insulin release leads to the onset of type 2 diabetes. To pinpoint the underlying primary driving force, here we have developed a fast, non-biased optical method to measure ratios of pancreatic α-and β-cell mass and function simultaneously. We firstly label both primary α-and β-cells with the red fluorescent probe ZinRhodaLactam-1 (ZRL1), and then highlight α-cells by selectively quenching the ZRL1 signal from β-cells. Based on the signals before and after quenching, we calculate the ratio of the α-cell to β-cell mass within live islets, which we found matched the results from immunohistochemistry. From the same islets, glucagon and insulin release capability can be concomitantly measured. Thus, we were able to measure the ratio of α-cell to β-cell mass and their function in wild-type and diabetic Lepr db /Lepr db (denoted db/db) mice at different ages. We find that the initial glucose intolerance that appears in 10-week-old db/db mice is associated with further expansion of α-cell mass prior to deterioration in functional β-cell mass. Our method is extendable to studies of islet mass and function in other type 2 diabetes animal models, which shall benefit mechanistic studies of imbalanced hormone secretion during type 2 diabetes progression.

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“…S3B,C). This finding suggests that 10-week-old db/db mice are already in the diabetic stage, which is consistent with previous studies (Do et al, 2014;Liang et al, 2014).…”

Section: Resultssupporting

confidence: 93%

Section: Discussionsupporting

confidence: 94%

Section: Isolation Of Mouse Pancreatic Islets and Dissociation Of Islmentioning

confidence: 99%

See 1 more Smart Citation

An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

Wang

Han

Zhu

et al. 2016

Journal of Cell Science

Self Cite

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“…Likely, this was a result of diminished [Ca 2+ ], as pharmacological elevation of [Ca 2+ ] via KATP inhibition or CaV stimulation recovered NFAT activation. We and others have measured diminished [Ca 2+ ] in multiple models of diabetes, with this disruption originating from altered glucose-sensing and mitochondrial dysfunction (9,41,49). However, [Ca 2+ ] oscillations are also disrupted in models of diabetes, showing shorter pulse duration (50).…”

Section: Dynamic β-Cell Electrical Activity Regulates Nfat Activationmentioning

confidence: 93%

Dynamic changes in β-cell electrical activity and [Ca²⁺] regulates NFATc3 activation and downstream gene transcription

Miranda¹,

Schleicher²,

Ramirez³

et al. 2020

Preprint

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AbstractDiabetes results from insufficient insulin secretion as a result of dysfunction to β-cells within the islet of Langerhans. Elevated glucose causes β-cell membrane depolarization and action potential generation, voltage gated Ca2+ channel activation and oscillations in free-Ca2+ activity ([Ca2+]), triggering insulin release. Nuclear Factor of Activated T-cell (NFAT) is a transcription factor that is regulated by increases in [Ca2+] and calceineurin (CaN) activation. NFAT regulation links cell activity with gene transcription in many systems, and within the β-cell regulates proliferation and insulin granule biogenesis. However the link between the regulation of β-cell electrical activity and oscillatory [Ca2+], with NFAT activation and downstream transcription is poorly understood. In this study we tested whether dynamic changes to β-cell electrical activity and [Ca2+] regulates NFAT activation and downstream transcription. In cell lines, mouse islets and human islets, including those from donors with type2 diabetes, we applied both agonists/antagonists of ion channels together with optogenetics to modulate β-cell electrical activity. Both glucose-induced membrane depolarization and optogenetic-stimulation triggered NFAT activation, and increased transcription of NFAT targets and intermediate early genes (IEGs). Importantly only conditions in which slow sustained [Ca2+] oscillations were generated led to NFAT activation and downstream transcription. In contrast in human islets from donors with type2 diabetes NFAT activation by glucose was diminished, but rescued upon pharmacological stimulation of electrical activity. Thus, we gain insight into the specific patterns of electrical activity that regulate NFAT activation and gene transcription and how this is disrupted in diabetes.

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“…Some evidence from animal models of diabetes supports this point of view (259,260). In both, obese (213,261) and non-obese (214,257,262) diabetic rodents, it has been observed that the progression of the diabetic state is accompanied by a gradual loss of SERCA pump activity and thus a defective electrical response of the ER. The reduced SERCA activity initially causes insulin hypersecretion (257) as would be expected from the stability diagram in Figure 6, but eventually the damage on the ER disrupts the secretory process causing hyperglycemia and the development of diabetes.…”

Section: On the Origin Of Type 2 Diabetes Mellitusmentioning

confidence: 95%

Electrical Excitability of the Endoplasmic Reticulum Membrane Drives Electrical Bursting and the Pulsatile Secretion of Insulin in a Pancreatic Beta Cell Model

Gómez-Barriocanal¹

2018

Preprint

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Pancreatic β-cells secrete insulin, the hormone that controls glucose homeostasis in vertebrates. When activated by glucose, β-cells display a biphasic electrical response. An initial phase, in which the cell fires action potentials continuously, is followed by a phase with a characteristic firing pattern, known as electrical bursting, that consists on brief pulses of action potentials separated by intervals of rest. Electrical bursting is believed to mediate the pulsatile secretion of insulin. The electrical response of β-cells has been extensively studied at experimental and theoretical level. However, there is still no consensus on the cellular mechanisms that underlie each of the phases of the response. In this paper, I propose the hypothesis that the pattern of the plasma membrane (PM) response of stimulated β-cells is generated by the electrical activity of the endoplasmic reticulum (ER) membrane. In this hypothesis, the interaction of the two excitable membranes, PM and ER membrane, each operating at a different time scale, generates both, the initial continuous phase and the periodic bursting The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/249805 doi: bioRxiv preprint first posted online mimics the actual effect of the factors on the frequency of bursting. Finally, the model shows that a cell with a defective ER response behaves like a dysfunctional β-cell from individuals with type 2 diabetes mellitus, a result that suggests that the electrical malfunction of the ER membrane may represent one of the primary causes of type 2 diabetes. Dynamic analysis of the ER behavior has revealed that, depending on the transport rates of Ca 2+ in and out of the ER, the system has three possible dynamic states. They consist on the hyperpolarization of the ER membrane, periodic oscillations of the electric potential across the membrane, and the depolarization of the membrane. Each of these states determines a different functional program in the cell. The hyperpolarized state maintains the cell at rest, in a non-secreting state. Periodic oscillations of the ER membrane cause electrical bursting in the PM and the consequent pulsatile secretion of insulin. Finally, the depolarized state causes continuous firing and an acute secretory activity, the hyperactive conditions of the initial phase of the β-cell response to glucose. The dynamic states of the ER are also associated with different long-term effects. So, conditions that induce the hyperactive depolarized state in β-cells also potentiate apoptosis. The induction of the oscillatory state by glucose and neuro-endocrine factors seems to activate also cell proliferation. In extreme conditions though, such as the chronic treatment of T2DM with incretin analogs, the activation of the oscillatory state may lead to the appearance of cancer. The mathematical model presented here is an illustration of how, even in a extremely simplified system, the nonlinearity or excitability of the ER membrane can produce a repertoire of dynamic state...

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Alterations of the Ca2+ signaling pathway in pancreatic beta-cells isolated from db/db mice

Cited by 15 publications

References 32 publications

An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

Dynamic changes in β-cell electrical activity and [Ca²⁺] regulates NFATc3 activation and downstream gene transcription

Electrical Excitability of the Endoplasmic Reticulum Membrane Drives Electrical Bursting and the Pulsatile Secretion of Insulin in a Pancreatic Beta Cell Model

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Alterations of the Ca2+ signaling pathway in pancreatic beta-cells isolated from db/db mice

Cited by 15 publications

References 32 publications

An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

Dynamic changes in β-cell electrical activity and [Ca2+] regulates NFATc3 activation and downstream gene transcription

Electrical Excitability of the Endoplasmic Reticulum Membrane Drives Electrical Bursting and the Pulsatile Secretion of Insulin in a Pancreatic Beta Cell Model

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Dynamic changes in β-cell electrical activity and [Ca²⁺] regulates NFATc3 activation and downstream gene transcription