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Batjargal T, Zappa F, Grant RJ, Piscopio RA, Chialastri A, Dey SS, Acosta-Alvear D, Wilson MZ. Optogenetic control of the integrated stress response reveals proportional encoding and the stress memory landscape. Cell Syst 2023; 14:551-562.e5. [PMID: 37473728 DOI: 10.1016/j.cels.2023.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 12/27/2022] [Accepted: 06/09/2023] [Indexed: 07/22/2023]
Abstract
The integrated stress response (ISR) is a conserved signaling network that detects aberrations and computes cellular responses. Dissecting these computations has been difficult because physical and chemical inducers of stress activate multiple parallel pathways. To overcome this challenge, we engineered a photo-switchable control over the ISR sensor kinase PKR (opto-PKR), enabling virtual, on-target activation. Using light to control opto-PKR dynamics, we traced information flow through the transcriptome and for key downstream ISR effectors. Our analyses revealed a biphasic, proportional transcriptional response with two dynamic modes, transient and gradual, that correspond to adaptive and terminal outcomes. We then constructed an ordinary differential equation (ODE) model of the ISR, which demonstrated the dependence of future stress responses on past stress. Finally, we tested our model using high-throughput light-delivery to map the stress memory landscape. Our results demonstrate that cells encode information in stress levels, durations, and the timing between encounters. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Taivan Batjargal
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Francesca Zappa
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Ryan J Grant
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Robert A Piscopio
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Alex Chialastri
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Siddharth S Dey
- Center for BioEngineering, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Diego Acosta-Alvear
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA.
| | - Maxwell Z Wilson
- Center for BioEngineering, University of California Santa Barbara, Santa Barbara, CA, USA; Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA.
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Farnsworth NL, Piscopio RA, Schleicher WE, Ramirez DG, Miranda JG, Benninger RKP. Modulation of Gap Junction Coupling Within the Islet of Langerhans During the Development of Type 1 Diabetes. Front Physiol 2022; 13:913611. [PMID: 35837011 PMCID: PMC9274093 DOI: 10.3389/fphys.2022.913611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/09/2022] [Indexed: 01/07/2023] Open
Abstract
In type 1 diabetes (T1D), islet dysfunction occurs prior to diabetes onset. Pro-inflammatory cytokines can disrupt insulin secretion and Ca2+ homeostasis. Connexin36 (Cx36) gap junctions electrically couple β-cells to coordinate glucose-stimulated Ca2+ and insulin secretion. Cx36 gap junction coupling can also protect against cytokine-induced apoptosis. Our goal was to determine how islet gap junction coupling and Ca2+ dynamics are altered in mouse models of T1D prior to diabetes. Glucose tolerance was assessed in NOD and immunodeficient NOD-RAG1KO mice at 6-12 weeks age. Glucose-stimulated insulin secretion, Ca2+ dynamics, and gap junction coupling were measured in islets isolated at each age. Gap junction coupling was also measured in islets from mice that underwent transfer of diabetogenic splenocytes and from chromograninA knockout NOD mice. Cell death was measured in islets isolated from wild-type, Cx36 knockout or Cx36 over-expression mice, each treated with a cocktail of pro-inflammatory cytokines and KATP or SERCA activators/inhibitors. NOD mice over-expressing Cx36 were also monitored for diabetes development, and islets assessed for insulitis and apoptosis. NOD and NOD-RAG1KO controls showed similar glucose tolerance at all ages. Ca2+ dynamics and gap junction coupling were disrupted in islets of NOD mice at 9 weeks, compared to controls. Transfer of diabetogenic splenocytes also decreased gap junction coupling. Islets from chromograninA knockout mice displayed normal coupling. Overexpression of Cx36 protected islets from cytokine-induced apoptosis. A knockout of Cx36 amplified cytokine-induced apoptosis, which was reversed by KATP activation or SERCA activation. Cx36 overexpression in NOD mice delayed diabetes development compared to NOD controls. However, apoptosis and insulitis were not improved. Decreases in islet gap junction coupling occur prior to T1D onset. Such decreases alter islet susceptibility to apoptosis due to altered Ca2+. Future studies will determine if increasing Cx36 gap junction coupling in combination with restoring Ca2+ homeostasis protects against islet decline in T1D.
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Affiliation(s)
- Nikki L. Farnsworth
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, United States,Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Robert A. Piscopio
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Wolfgang E. Schleicher
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - David G. Ramirez
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jose G. Miranda
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Richard K. P. Benninger
- Barbara Davis Center for Diabetes, Universty of Colorado Anschutz Medical Campus, Aurora, CO, United States,Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO, United States,*Correspondence: Richard K. P. Benninger,
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Fontaine AK, Ramirez DG, Littich SF, Piscopio RA, Kravets V, Schleicher WE, Mizoguchi N, Caldwell JH, Weir RFF, Benninger RKP. Optogenetic stimulation of cholinergic fibers for the modulation of insulin and glycemia. Sci Rep 2021; 11:3670. [PMID: 33574598 PMCID: PMC7878862 DOI: 10.1038/s41598-021-83361-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 02/01/2021] [Indexed: 01/12/2023] Open
Abstract
Previous studies have demonstrated stimulation of endocrine pancreas function by vagal nerve electrical stimulation. While this increases insulin secretion, expected concomitant reductions in circulating glucose do not occur. A complicating factor is the non-specific nature of electrical nerve stimulation. Optogenetic tools, however, provide the potential for cell-type specific neural stimulation using genetic targeting and/or spatially shaped excitation light. Here, we demonstrate light-activated stimulation of the endocrine pancreas by targeting parasympathetic (cholinergic) axons. In a mouse model expressing ChannelRhodopsin2 (ChR2) in cholinergic cells, serum insulin and glucose were measured in response to (1) ultrasound image-guided optical stimulation of axon terminals in the pancreas or (2) optical stimulation of axons of the cervical vagus nerve. Measurements were made in basal-glucose and glucose-stimulated conditions. Significant increases in plasma insulin occurred relative to controls under both pancreas and cervical vagal stimulation, while a rapid reduction in glycemic levels were observed under pancreatic stimulation. Additionally, ultrasound-based measurements of blood flow in the pancreas were increased under pancreatic stimulation. Together, these results demonstrate the utility of in-vivo optogenetics for studying the neural regulation of endocrine pancreas function and suggest its therapeutic potential for the control of insulin secretion and glucose homeostasis.
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Affiliation(s)
- Arjun K Fontaine
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Boulder, USA.
- Biomechatronics Development Laboratory, University of Colorado, Anschutz Medical Campus, Boulder, USA.
| | - David G Ramirez
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Boulder, USA
- Barbara Davis Center for Childhood Diabetes - Anschutz Medical Campus, Boulder, USA
| | - Samuel F Littich
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Boulder, USA
- Biomechatronics Development Laboratory, University of Colorado, Anschutz Medical Campus, Boulder, USA
| | - Robert A Piscopio
- Barbara Davis Center for Childhood Diabetes - Anschutz Medical Campus, Boulder, USA
| | - Vira Kravets
- Barbara Davis Center for Childhood Diabetes - Anschutz Medical Campus, Boulder, USA
| | | | - Naoko Mizoguchi
- Division of Pharmacology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, Saitama, Japan
| | - John H Caldwell
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Boulder, USA
| | - Richard F Ff Weir
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Boulder, USA
- Biomechatronics Development Laboratory, University of Colorado, Anschutz Medical Campus, Boulder, USA
| | - Richard K P Benninger
- Department of Bioengineering, University of Colorado, Anschutz Medical Campus, Boulder, USA.
- Barbara Davis Center for Childhood Diabetes - Anschutz Medical Campus, Boulder, USA.
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Farnsworth NL, Walter R, Piscopio RA, Schleicher WE, Benninger RKP. Exendin-4 overcomes cytokine-induced decreases in gap junction coupling via protein kinase A and Epac2 in mouse and human islets. J Physiol 2019; 597:431-447. [PMID: 30412665 PMCID: PMC6332825 DOI: 10.1113/jp276106] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 11/07/2018] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS The pancreatic islets of Langerhans maintain glucose homeostasis through insulin secretion, where insulin secretion dynamics are regulated by intracellular Ca2+ signalling and electrical coupling of the insulin producing β-cells in the islet. We have previously shown that cytokines decrease β-cell coupling and that compounds which increase cAMP can increase coupling. In both mouse and human islets exendin-4, which increases cAMP, protected against cytokine-induced decreases in coupling and in mouse islets preserved glucose-stimulated calcium signalling by increasing connexin36 gap junction levels on the plasma membrane. Our data indicate that protein kinase A regulates β-cell coupling through a fast mechanism, such as channel gating or membrane organization, while Epac2 regulates slower mechanisms of regulation, such as gap junction turnover. Increases in β-cell coupling with exendin-4 may protect against cytokine-mediated β-cell death as well as preserve insulin secretion dynamics during the development of diabetes. ABSTRACT The pancreatic islets of Langerhans maintain glucose homeostasis. Insulin secretion from islet β-cells is driven by glucose metabolism, depolarization of the cell membrane and an influx of calcium, which initiates the release of insulin. Gap junctions composed of connexin36 (Cx36) electrically couple β-cells, regulating calcium signalling and insulin secretion dynamics. Cx36 coupling is decreased in pre-diabetic mice, suggesting a role for altered coupling in diabetes. Our previous work has shown that pro-inflammatory cytokines decrease Cx36 coupling and that compounds which increase cAMP can increase Cx36 coupling. The goal of this study was to determine if exendin-4, which increases cAMP, can protect against cytokine-induced decreases in Cx36 coupling and altered islet function. In both mouse and human islets, exendin-4 protected against cytokine-induced decreases in coupling and preserved glucose-stimulated calcium signalling. Exendin-4 also protected against protein kinase Cδ-mediated decreases in Cx36 coupling. Exendin-4 preserved coupling in mouse islets by preserving Cx36 levels on the plasma membrane. Exendin-4 regulated Cx36 coupling via both protein kinase A (PKA)- and Epac2-mediated mechanisms in cytokine-treated islets. In mouse islets, modulating Epac2 had a greater impact in mediating Cx36 coupling, while in human islets modulating PKA had a greater impact on Cx36 coupling. Our data indicate that PKA regulates Cx36 coupling through a fast mechanism, such as channel gating, while Epac2 regulates slower mechanisms of regulation, such as Cx36 turnover in the membrane. Increases in Cx36 coupling with exendin-4 may protect against cytokine-mediated β-cell dysfunction to insulin secretion dynamics during the development of diabetes.
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Affiliation(s)
- Nikki L. Farnsworth
- Barbara Davis Center for Childhood DiabetesUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Rachelle Walter
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Robert A. Piscopio
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Wolfgang E. Schleicher
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
| | - Richard K. P. Benninger
- Barbara Davis Center for Childhood DiabetesUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
- Department of BioengineeringUniversity of Colorado Anschutz Medical CampusAuroraCO80045USA
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