1
|
Paradiž Leitgeb E, Kerčmar J, Križančić Bombek L, Pohorec V, Skelin Klemen M, Slak Rupnik M, Gosak M, Dolenšek J, Stožer A. Exendin-4 affects calcium signalling predominantly during activation and activity of beta cell networks in acute mouse pancreas tissue slices. Front Endocrinol (Lausanne) 2024; 14:1315520. [PMID: 38292770 PMCID: PMC10826511 DOI: 10.3389/fendo.2023.1315520] [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] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/22/2023] [Indexed: 02/01/2024] Open
Abstract
Tight control of beta cell stimulus-secretion coupling is crucial for maintaining homeostasis of energy-rich nutrients. While glucose serves as a primary regulator of this process, incretins augment beta cell function, partly by enhancing cytosolic [Ca2+] dynamics. However, the details of how precisely they affect beta cell recruitment during activation, their active time, and functional connectivity during plateau activity, and how they influence beta cell deactivation remain to be described. Performing functional multicellular Ca2+ imaging in acute mouse pancreas tissue slices enabled us to systematically assess the effects of the GLP-1 receptor agonist exendin-4 (Ex-4) simultaneously in many coupled beta cells with high resolution. In otherwise substimulatory glucose, Ex-4 was able to recruit approximately a quarter of beta cells into an active state. Costimulation with Ex-4 and stimulatory glucose shortened the activation delays and accelerated beta cell activation dynamics. More specifically, active time increased faster, and the time required to reach half-maximal activation was effectively halved in the presence of Ex-4. Moreover, the active time and regularity of [Ca2+]IC oscillations increased, especially during the first part of beta cell response. In contrast, subsequent addition of Ex-4 to already active cells did not significantly enhance beta cell activity. Network analyses further confirmed increased connectivity during activation and activity in the presence of Ex-4, with hub cell roles remaining rather stable in both control experiments and experiments with Ex-4. Interestingly, Ex-4 demonstrated a biphasic effect on deactivation, slightly prolonging beta cell activity at physiological concentrations and shortening deactivation delays at supraphysiological concentrations. In sum, costimulation by Ex-4 and glucose increases [Ca2+]IC during beta cell activation and activity, indicating that the effect of incretins may, to an important extent, be explained by enhanced [Ca2+]IC signals. During deactivation, previous incretin stimulation does not critically prolong cellular activity, which corroborates their low risk of hypoglycemia.
Collapse
Affiliation(s)
- Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jasmina Kerčmar
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Vilijem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| |
Collapse
|
2
|
Cohrs CM, Chen C, Atkinson MA, Drotar DM, Speier S. Bridging the Gap: Pancreas Tissue Slices From Organ and Tissue Donors for the Study of Diabetes Pathogenesis. Diabetes 2024; 73:11-22. [PMID: 38117999 PMCID: PMC10784654 DOI: 10.2337/dbi20-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/14/2023] [Indexed: 12/22/2023]
Abstract
Over the last two decades, increased availability of human pancreatic tissues has allowed for major expansions in our understanding of islet biology in health and disease. Indeed, studies of fixed and frozen pancreatic tissues, as well as efforts using viable isolated islets obtained from organ donors, have provided significant insights toward our understanding of diabetes. However, the procedures associated with islet isolation result in distressed cells that have been removed from any surrounding influence. The pancreas tissue slice technology was developed as an in situ approach to overcome certain limitations associated with studies on isolated islets or fixed tissue. In this Perspective, we discuss the value of this novel platform and review how pancreas tissue slices, within a short time, have been integrated in numerous studies of rodent and human islet research. We show that pancreas tissue slices allow for investigations in a less perturbed organ tissue environment, ranging from cellular processes, over peri-islet modulations, to tissue interactions. Finally, we discuss the considerations and limitations of this technology in its future applications. We believe the pancreas tissue slices will help bridge the gap between studies on isolated islets and cells to the systemic conditions by providing new insight into physiological and pathophysiological processes at the organ level. ARTICLE HIGHLIGHTS Human pancreas tissue slices represent a novel platform to study human islet biology in close to physiological conditions. Complementary to established technologies, such as isolated islets, single cells, and histological sections, pancreas tissue slices help bridge our understanding of islet physiology and pathophysiology from single cell to intact organ. Diverse sources of viable human pancreas tissue, each with distinct characteristics to be considered, are available to use in tissue slices for the study of diabetes pathogenesis.
Collapse
Affiliation(s)
- Christian M. Cohrs
- Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of Helmholtz Munich at the University Hospital and Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Chunguang Chen
- Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of Helmholtz Munich at the University Hospital and Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Mark A. Atkinson
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, FL
| | - Denise M. Drotar
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida Diabetes Institute, Gainesville, FL
| | - Stephan Speier
- Institute of Physiology, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of Helmholtz Munich at the University Hospital and Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| |
Collapse
|
3
|
Briggs JK, Gresch A, Marinelli I, Dwulet JM, Albers DJ, Kravets V, Benninger RKP. β-cell intrinsic dynamics rather than gap junction structure dictates subpopulations in the islet functional network. eLife 2023; 12:e83147. [PMID: 38018905 PMCID: PMC10803032 DOI: 10.7554/elife.83147] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 08/31/2022] [Accepted: 11/27/2023] [Indexed: 11/30/2023] Open
Abstract
Diabetes is caused by the inability of electrically coupled, functionally heterogeneous β-cells within the pancreatic islet to provide adequate insulin secretion. Functional networks have been used to represent synchronized oscillatory [Ca2+] dynamics and to study β-cell subpopulations, which play an important role in driving islet function. The mechanism by which highly synchronized β-cell subpopulations drive islet function is unclear. We used experimental and computational techniques to investigate the relationship between functional networks, structural (gap junction) networks, and intrinsic β-cell dynamics in slow and fast oscillating islets. Highly synchronized subpopulations in the functional network were differentiated by intrinsic dynamics, including metabolic activity and KATP channel conductance, more than structural coupling. Consistent with this, intrinsic dynamics were more predictive of high synchronization in the islet functional network as compared to high levels of structural coupling. Finally, dysfunction of gap junctions, which can occur in diabetes, caused decreases in the efficiency and clustering of the functional network. These results indicate that intrinsic dynamics rather than structure drive connections in the functional network and highly synchronized subpopulations, but gap junctions are still essential for overall network efficiency. These findings deepen our interpretation of functional networks and the formation of functional subpopulations in dynamic tissues such as the islet.
Collapse
Affiliation(s)
- Jennifer K Briggs
- Department of Bioengineering, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Anne Gresch
- Department of Bioengineering, University of Colorado Anschutz Medical CampusAuroraUnited States
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Isabella Marinelli
- Centre for Systems Modelling and Quantitative Biomedicine, University of BirminghamBirminghamUnited Kingdom
| | - JaeAnn M Dwulet
- Department of Bioengineering, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - David J Albers
- Department of Bioengineering, University of Colorado Anschutz Medical CampusAuroraUnited States
- Department of Biomedical Informatics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Vira Kravets
- Department of Bioengineering, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Richard KP Benninger
- Department of Bioengineering, University of Colorado Anschutz Medical CampusAuroraUnited States
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical CampusAuroraUnited States
| |
Collapse
|
4
|
Šterk M, Barać U, Stožer A, Gosak M. Both electrical and metabolic coupling shape the collective multimodal activity and functional connectivity patterns in beta cell collectives: A computational model perspective. Phys Rev E 2023; 108:054409. [PMID: 38115462 DOI: 10.1103/physreve.108.054409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 10/20/2023] [Indexed: 12/21/2023]
Abstract
Pancreatic beta cells are coupled excitable oscillators that synchronize their activity via different communication pathways. Their oscillatory activity manifests itself on multiple timescales and consists of bursting electrical activity, subsequent oscillations in the intracellular Ca^{2+}, as well as oscillations in metabolism and exocytosis. The coordination of the intricate activity on the multicellular level plays a key role in the regulation of physiological pulsatile insulin secretion and is incompletely understood. In this paper, we investigate theoretically the principles that give rise to the synchronized activity of beta cell populations by building up a phenomenological multicellular model that incorporates the basic features of beta cell dynamics. Specifically, the model is composed of coupled slow and fast oscillatory units that reflect metabolic processes and electrical activity, respectively. Using a realistic description of the intercellular interactions, we study how the combination of electrical and metabolic coupling generates collective rhythmicity and shapes functional beta cell networks. It turns out that while electrical coupling solely can synchronize the responses, the addition of metabolic interactions further enhances coordination, the spatial range of interactions increases the number of connections in the functional beta cell networks, and ensures a better consistency with experimental findings. Moreover, our computational results provide additional insights into the relationship between beta cell heterogeneity, their activity profiles, and functional connectivity, supplementing thereby recent experimental results on endocrine networks.
Collapse
Affiliation(s)
- Marko Šterk
- Department of Physics, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, University of Maribor, 2000 Maribor, Slovenia
- Institute of Physiology, Faculty of Medicine, Taborska ulica 8, University of Maribor, 2000 Maribor, Slovenia
- Alma Mater Europaea, Slovenska ulica 17, 2000 Maribor, Slovenia
| | - Uroš Barać
- Department of Physics, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, University of Maribor, 2000 Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, Taborska ulica 8, University of Maribor, 2000 Maribor, Slovenia
| | - Marko Gosak
- Department of Physics, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, University of Maribor, 2000 Maribor, Slovenia
- Institute of Physiology, Faculty of Medicine, Taborska ulica 8, University of Maribor, 2000 Maribor, Slovenia
- Alma Mater Europaea, Slovenska ulica 17, 2000 Maribor, Slovenia
| |
Collapse
|
5
|
Goekoop R, de Kleijn R. Hierarchical network structure as the source of hierarchical dynamics (power-law frequency spectra) in living and non-living systems: How state-trait continua (body plans, personalities) emerge from first principles in biophysics. Neurosci Biobehav Rev 2023; 154:105402. [PMID: 37741517 DOI: 10.1016/j.neubiorev.2023.105402] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 09/25/2023]
Abstract
Living systems are hierarchical control systems that display a small world network structure. In such structures, many smaller clusters are nested within fewer larger ones, producing a fractal-like structure with a 'power-law' cluster size distribution (a mereology). Just like their structure, the dynamics of living systems shows fractal-like qualities: the timeseries of inner message passing and overt behavior contain high frequencies or 'states' (treble) that are nested within lower frequencies or 'traits' (bass), producing a power-law frequency spectrum that is known as a 'state-trait continuum' in the behavioral sciences. Here, we argue that the power-law dynamics of living systems results from their power-law network structure: organisms 'vertically encode' the deep spatiotemporal structure of their (anticipated) environments, to the effect that many small clusters near the base of the hierarchy produce high frequency signal changes and fewer larger clusters at its top produce ultra-low frequencies. Such ultra-low frequencies exert a tonic regulatory pressure that produces morphological as well as behavioral traits (i.e., body plans and personalities). Nested-modular structure causes higher frequencies to be embedded within lower frequencies, producing a power-law state-trait continuum. At the heart of such dynamics lies the need for efficient energy dissipation through networks of coupled oscillators, which also governs the dynamics of non-living systems (e.q., earthquakes, stock market fluctuations). Since hierarchical structure produces hierarchical dynamics, the development and collapse of hierarchical structure (e.g., during maturation and disease) should leave specific traces in system dynamics (shifts in lower frequencies, i.e. morphological and behavioral traits) that may serve as early warning signs to system failure. The applications of this idea range from (bio)physics and phylogenesis to ontogenesis and clinical medicine.
Collapse
Affiliation(s)
- R Goekoop
- Free University Amsterdam, Department of Behavioral and Movement Sciences, Parnassia Academy, Parnassia Group, PsyQ, Department of Anxiety Disorders, Early Detection and Intervention Team (EDIT), Lijnbaan 4, 2512VA The Hague, the Netherlands.
| | - R de Kleijn
- Faculty of Social and Behavioral Sciences, Department of Cognitive Psychology, Pieter de la Courtgebouw, Postbus 9555, 2300 RB Leiden, the Netherlands
| |
Collapse
|
6
|
Veron G, Maltsev VA, Stern MD, Maltsev AV. Elementary intracellular Ca signals approximated as a transition of release channel system from a metastable state. J Appl Phys 2023; 134:124701. [PMID: 37744735 PMCID: PMC10517864 DOI: 10.1063/5.0151255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 09/04/2023] [Indexed: 09/26/2023]
Abstract
Cardiac muscle contraction is initiated by an elementary Ca signal (called Ca spark) which is achieved by collective action of Ca release channels in a cluster. The mechanism of this synchronization remains uncertain. We approached Ca spark activation as an emergent phenomenon of an interactive system of release channels. We constructed a weakly lumped Markov chain that applies an Ising model formalism to such release channel clusters and probable open channel configurations and demonstrated that spark activation is described as a system transition from a metastable to an absorbing state, analogous to the pressure required to overcome surface tension in bubble formation. This yielded quantitative estimates of the spark generation probability as a function of various system parameters. We performed numerical simulations to find spark probabilities as a function of sarcoplasmic reticulum Ca concentration, obtaining similar values for spark activation threshold as our analytic model, as well as those reported in experimental studies. Our parametric sensitivity analyses also showed that the spark activation threshold decreased as Ca sensitivity of RyR activation and RyR cluster size increased.
Collapse
Affiliation(s)
- Guillermo Veron
- Cellular Biophysics Section, Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Victor A. Maltsev
- Cellular Biophysics Section, Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Michael D. Stern
- Cellular Biophysics Section, Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Anna V. Maltsev
- School of Mathematical Sciences, Queen Mary University of London, London E14NS, United Kingdom
| |
Collapse
|
7
|
Skelin Klemen M, Dolenšek J, Križančić Bombek L, Pohorec V, Gosak M, Slak Rupnik M, Stožer A. The effect of forskolin and the role of Epac2A during activation, activity, and deactivation of beta cell networks. Front Endocrinol (Lausanne) 2023; 14:1225486. [PMID: 37701894 PMCID: PMC10494243 DOI: 10.3389/fendo.2023.1225486] [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] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/08/2023] [Indexed: 09/14/2023] Open
Abstract
Beta cells couple stimulation by glucose with insulin secretion and impairments in this coupling play a central role in diabetes mellitus. Cyclic adenosine monophosphate (cAMP) amplifies stimulus-secretion coupling via protein kinase A and guanine nucleotide exchange protein 2 (Epac2A). With the present research, we aimed to clarify the influence of cAMP-elevating diterpene forskolin on cytoplasmic calcium dynamics and intercellular network activity, which are two of the crucial elements of normal beta cell stimulus-secretion coupling, and the role of Epac2A under normal and stimulated conditions. To this end, we performed functional multicellular calcium imaging of beta cells in mouse pancreas tissue slices after stimulation with glucose and forskolin in wild-type and Epac2A knock-out mice. Forskolin evoked calcium signals in otherwise substimulatory glucose and beta cells from Epac2A knock-out mice displayed a faster activation. During the plateau phase, beta cells from Epac2A knock-out mice displayed a slightly higher active time in response to glucose compared with wild-type littermates, and stimulation with forskolin increased the active time via an increase in oscillation frequency and a decrease in oscillation duration in both Epac2A knock-out and wild-type mice. Functional network properties during stimulation with glucose did not differ in Epac2A knock-out mice, but the presence of Epac2A was crucial for the protective effect of stimulation with forskolin in preventing a decline in beta cell functional connectivity with time. Finally, stimulation with forskolin prolonged beta cell activity during deactivation, especially in Epac2A knock-out mice.
Collapse
Affiliation(s)
- Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, European Center Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea, European Center Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| |
Collapse
|
8
|
Šterk M, Dolenšek J, Skelin Klemen M, Križančić Bombek L, Paradiž Leitgeb E, Kerčmar J, Perc M, Slak Rupnik M, Stožer A, Gosak M. Functional characteristics of hub and wave-initiator cells in β cell networks. Biophys J 2023; 122:784-801. [PMID: 36738106 PMCID: PMC10027448 DOI: 10.1016/j.bpj.2023.01.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/22/2022] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
Islets of Langerhans operate as multicellular networks in which several hundred β cells work in synchrony to produce secretory pulses of insulin, a hormone crucial for controlling metabolic homeostasis. Their collective rhythmic activity is facilitated by gap junctional coupling and affected by their functional heterogeneity, but the details of this robust and coordinated behavior are still not fully understood. Recent advances in multicellular imaging and optogenetic and photopharmacological strategies, as well as in network science, have led to the discovery of specialized β cell subpopulations that were suggested to critically determine the collective dynamics in the islets. In particular hubs, i.e., β cells with many functional connections, are believed to significantly enhance communication capacities of the intercellular network and facilitate an efficient spreading of intercellular Ca2+ waves, whereas wave-initiator cells trigger intercellular signals in their cohorts. Here, we determined Ca2+ signaling characteristics of these two β cell subpopulations and the relationship between them by means of functional multicellular Ca2+ imaging in mouse pancreatic tissue slices in combination with methods of complex network theory. We constructed network layers based on individual Ca2+ waves to identify wave initiators, and functional correlation-based networks to detect hubs. We found that both cell types exhibit a higher-than-average active time under both physiological and supraphysiological glucose concentrations, but also that they differ significantly in many other functional characteristics. Specifically, Ca2+ oscillations in hubs are more regular, and their role appears to be much more stable over time than for initiator cells. Moreover, in contrast to wave initiators, hubs transmit intercellular signals faster than other cells, which implies a stronger intercellular coupling. Our research indicates that hubs and wave-initiator cell subpopulations are both natural features of healthy pancreatic islets, but their functional roles in principle do not overlap and should thus not be considered equal.
Collapse
Affiliation(s)
- Marko Šterk
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | | | | | - Jasmina Kerčmar
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Matjaž Perc
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; Alma Mater Europaea, Maribor, Slovenia; Complexity Science Hub Vienna, Vienna, Austria; Department of Physics, Kyung Hee University, Dongdaemun-gu, Seoul, Republic of Korea
| | - Marjan Slak Rupnik
- Faculty of Medicine, University of Maribor, Maribor, Slovenia; Alma Mater Europaea, Maribor, Slovenia; Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, Maribor, Slovenia.
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia; Faculty of Medicine, University of Maribor, Maribor, Slovenia; Alma Mater Europaea, Maribor, Slovenia.
| |
Collapse
|
9
|
Müller M, Walkling J, Seemann N, Rustenbeck I. The Dynamics of Calcium Signaling in Beta Cells-A Discussion on the Comparison of Experimental and Modelling Data. Int J Mol Sci 2023; 24:ijms24043206. [PMID: 36834618 PMCID: PMC9960854 DOI: 10.3390/ijms24043206] [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] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 02/07/2023] Open
Abstract
The stimulus-secretion coupling of the pancreatic beta cell is particularly complex, as it integrates the availability of glucose and other nutrients with the neuronal and hormonal input to generate rates of insulin secretion that are appropriate for the entire organism. It is beyond dispute however, that the cytosolic Ca2+ concentration plays a particularly prominent role in this process, as it not only triggers the fusion of insulin granules with the plasma membrane, but also regulates the metabolism of nutrient secretagogues and affects the function of ion channels and transporters. In order to obtain a better understanding of the interdependence of these processes and, ultimately, of the entire beta cell as a working system, models have been developed based on a set of nonlinear ordinary differential equations, and were tested and parametrized on a limited set of experiments. In the present investigation, we have used a recently published version of the beta cell model to test its ability to describe further measurements from our own experimentation and from the literature. The sensitivity of the parameters is quantified and discussed; furthermore, the possible influence of the measuring technique is taken into account. The model proved to be powerful in correctly describing the depolarization pattern in response to glucose and the reaction of the cytosolic Ca2+ concentration to stepwise increases of the extracellular K+ concentration. Additionally, the membrane potential during a KATP channel block combined with a high extracellular K+ concentration could be reproduced. In some cases, however, a slight change of a single parameter led to an abrupt change in the cellular response, such as the generation of a Ca2+ oscillation with high amplitude and high frequency. This raises the question as to whether the beta cell may be a partially unstable system or whether further developments in modeling are needed to achieve a generally valid description of the stimulus-secretion coupling of the beta cell.
Collapse
Affiliation(s)
- Michael Müller
- Institute of Dynamics and Vibrations, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
- Correspondence: (M.M.); (I.R.); Tel.: +49-531-391-7005 (M.M.);+49-531-391-5670 (I.R.)
| | - Jonas Walkling
- Institute of Dynamics and Vibrations, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
| | - Nele Seemann
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
| | - Ingo Rustenbeck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
- Correspondence: (M.M.); (I.R.); Tel.: +49-531-391-7005 (M.M.);+49-531-391-5670 (I.R.)
| |
Collapse
|
10
|
Rached G, Saliba Y, Maddah D, Hajal J, Smayra V, Bakhos J, Groschner K, Birnbaumer L, Fares N. TRPC3 Regulates Islet Beta-Cell Insulin Secretion. Adv Sci (Weinh) 2023; 10:e2204846. [PMID: 36642838 PMCID: PMC9951314 DOI: 10.1002/advs.202204846] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Insulin release is tightly controlled by glucose-stimulated calcium (GSCa) through hitherto equivocal pathways. This study investigates TRPC3, a non-selective cation channel, as a critical regulator of insulin secretion and glucose control. TRPC3's involvement in glucose-stimulated insulin secretion (GSIS) is studied in human and animal islets. TRPC3-dependent in vivo insulin secretion is investigated using pharmacological tools and Trpc3-/- mice. TRPC3's involvement in islet glucose uptake and GSCa is explored using fluorescent glucose analogue 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose and calcium imaging. TRPC3 modulation by a small-molecule activator, GSK1702934A, is evaluated in type 2 diabetic mice. TRPC3 is functionally expressed in human and mouse islet beta cells. TRPC3-controlled insulin secretion is KATP -independent and primarily mediated by diacylglycerol channel regulation of the cytosolic calcium oscillations following glucose stimulation. Conversely, glucose uptake in islets is independent of TRPC3. TRPC3 pharmacologic inhibition and knockout in mice lead to defective insulin secretion and glucose intolerance. Subsequently, TRPC3 activation through targeted small-molecule enhances insulin secretion and alleviates diabetes hallmarks in animals. This study imputes a function for TRPC3 at the onset of GSIS. These insights strengthen one's knowledge of insulin secretion physiology and set forth the TRPC3 channel as an appealing candidate for drug development in the treatment of diabetes.
Collapse
Affiliation(s)
- Gaëlle Rached
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Youakim Saliba
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Dina Maddah
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Joelle Hajal
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Viviane Smayra
- Faculty of MedicineSaint Joseph UniversitySaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Jules‐Joel Bakhos
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| | - Klaus Groschner
- Gottfried‐Schatz‐Research‐Centre‐BiophysicsMedical University of GrazGraz8010Austria
| | - Lutz Birnbaumer
- School of Medical SciencesInstitute of Biomedical Research (BIOMED)Catholic University of ArgentinaBuenos AiresC1107AAZArgentina
- Signal Transduction LaboratoryNational Institute of Environmental Health SciencesResearch Triangle ParkDurhamNCC1107AAZUSA
| | - Nassim Fares
- Physiology and Pathophysiology Research LaboratoryPole of Technology and HealthFaculty of MedicineSaint Joseph University of BeirutPOBox. 17‐5208 ‐ Mar MikhaëlBeirut1104 2020Lebanon
| |
Collapse
|
11
|
Bahadoran Z, Mirmiran P, Kashfi K, Ghasemi A. Carbon monoxide and β-cell function: Implications for type 2 diabetes mellitus. Biochem Pharmacol 2022; 201:115048. [PMID: 35460631 DOI: 10.1016/j.bcp.2022.115048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 01/17/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 11/24/2022]
Abstract
Carbon monoxide (CO), a member of the multifunctional gasotransmitters family produced by heme oxygenases (i.e., HO-1 and HO-2), has received significant attention because of its involvement in carbohydrate metabolism. Experimental evidence indicates that both HO-2- and HO-1-derived CO stimulate insulin secretion, but the latter mainly acts as a compensatory response in pre-diabetes conditions. CO protects pancreatic β-cell against cytokine- and hypoxia-induced apoptosis and promotes β-cell regeneration. CO cross-talks with nitric oxide (NO) and hydrogen sulfide (H2S), other important gasotransmitters in carbohydrate metabolism, in regulating β-cell function and insulin secretion. These data speak in favor of the potential therapeutic application of CO in type 2 diabetes mellitus (T2DM) and preventing the progression of pre-diabetes to diabetes. Either CO (as both gaseous form and CO-releasing molecule) or pharmacological formulations made of natural HO inducers (i.e., bioactive components originating from plant-based foods) are potential candidates for developing CO-based therapeutics in T2DM. Future studies are needed to assess the safety/efficacy and potential therapeutic applications of CO in T2DM.
Collapse
Affiliation(s)
- Zahra Bahadoran
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Parvin Mirmiran
- Department of Clinical Nutrition and Human Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Khosrow Kashfi
- Department of Molecular, Cellular, and Biomedical Sciences, Sophie Davis School of Biomedical Education, City University of New York School of Medicine, New York, NY 10031, USA; Graduate Program in Biology, City University of New York Graduate Center, New York, NY 10091, USA
| | - Asghar Ghasemi
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
12
|
Pohorec V, Križančić Bombek L, Skelin Klemen M, Dolenšek J, Stožer A. Glucose-Stimulated Calcium Dynamics in Beta Cells From Male C57BL/6J, C57BL/6N, and NMRI Mice: A Comparison of Activation, Activity, and Deactivation Properties in Tissue Slices. Front Endocrinol (Lausanne) 2022; 13:867663. [PMID: 35399951 PMCID: PMC8988149 DOI: 10.3389/fendo.2022.867663] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 02/23/2022] [Indexed: 11/13/2022] Open
Abstract
Although mice are a very instrumental model in islet beta cell research, possible phenotypic differences between strains and substrains are largely neglected in the scientific community. In this study, we show important phenotypic differences in beta cell responses to glucose between C57BL/6J, C57BL/6N, and NMRI mice, i.e., the three most commonly used strains. High-resolution multicellular confocal imaging of beta cells in acute pancreas tissue slices was used to measure and quantitatively compare the calcium dynamics in response to a wide range of glucose concentrations. Strain- and substrain-specific features were found in all three phases of beta cell responses to glucose: a shift in the dose-response curve characterizing the delay to activation and deactivation in response to stimulus onset and termination, respectively, and distinct concentration-encoding principles during the plateau phase in terms of frequency, duration, and active time changes with increasing glucose concentrations. Our results underline the significance of carefully choosing and reporting the strain to enable comparison and increase reproducibility, emphasize the importance of analyzing a number of different beta cell physiological parameters characterizing the response to glucose, and provide a valuable standard for future studies on beta cell calcium dynamics in health and disease in tissue slices.
Collapse
Affiliation(s)
- Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- *Correspondence: Andraž Stožer, ; Jurij Dolenšek,
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- *Correspondence: Andraž Stožer, ; Jurij Dolenšek,
| |
Collapse
|
13
|
Stožer A, Šterk M, Paradiž Leitgeb E, Markovič R, Skelin Klemen M, Ellis CE, Križančić Bombek L, Dolenšek J, MacDonald PE, Gosak M. From Isles of Königsberg to Islets of Langerhans: Examining the Function of the Endocrine Pancreas Through Network Science. Front Endocrinol (Lausanne) 2022; 13:922640. [PMID: 35784543 PMCID: PMC9240343 DOI: 10.3389/fendo.2022.922640] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 05/16/2022] [Indexed: 12/12/2022] Open
Abstract
Islets of Langerhans are multicellular microorgans located in the pancreas that play a central role in whole-body energy homeostasis. Through secretion of insulin and other hormones they regulate postprandial storage and interprandial usage of energy-rich nutrients. In these clusters of hormone-secreting endocrine cells, intricate cell-cell communication is essential for proper function. Electrical coupling between the insulin-secreting beta cells through gap junctions composed of connexin36 is particularly important, as it provides the required, most important, basis for coordinated responses of the beta cell population. The increasing evidence that gap-junctional communication and its modulation are vital to well-regulated secretion of insulin has stimulated immense interest in how subpopulations of heterogeneous beta cells are functionally arranged throughout the islets and how they mediate intercellular signals. In the last decade, several novel techniques have been proposed to assess cooperation between cells in islets, including the prosperous combination of multicellular imaging and network science. In the present contribution, we review recent advances related to the application of complex network approaches to uncover the functional connectivity patterns among cells within the islets. We first provide an accessible introduction to the basic principles of network theory, enumerating the measures characterizing the intercellular interactions and quantifying the functional integration and segregation of a multicellular system. Then we describe methodological approaches to construct functional beta cell networks, point out possible pitfalls, and specify the functional implications of beta cell network examinations. We continue by highlighting the recent findings obtained through advanced multicellular imaging techniques supported by network-based analyses, giving special emphasis to the current developments in both mouse and human islets, as well as outlining challenges offered by the multilayer network formalism in exploring the collective activity of islet cell populations. Finally, we emphasize that the combination of these imaging techniques and network-based analyses does not only represent an innovative concept that can be used to describe and interpret the physiology of islets, but also provides fertile ground for delineating normal from pathological function and for quantifying the changes in islet communication networks associated with the development of diabetes mellitus.
Collapse
Affiliation(s)
- Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marko Šterk
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Rene Markovič
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Institute of Mathematics and Physics, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Cara E. Ellis
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | | | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Patrick E. MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- *Correspondence: Marko Gosak,
| |
Collapse
|
14
|
Abstract
The continuous interaction between experimental and theoretical work has proven to be extremely useful for the study of pancreatic cells and, recently, of pancreatic islets. This prolific interaction relies on the capability of implementing computational models and methods to derive quantitative data for the analysis and interpretation of experimental observations. In this addendum I introduce Isletlab, a multiplatform application developed to provide the research community with a user-friendly interface for the implementation of computational algorithms for the characterization and simulation of pancreatic islets.
Collapse
Affiliation(s)
- Gerardo J. Félix-Martínez
- Cátedras CONACYT, Consejo Nacional de Ciencia y Tecnología, México City, México
- Department of Electrical Engineering, Universidad Autónoma Metropolitana, México City, México
- CONTACT Gerardo J. Félix-Martínez ; ; Laboratorio de Biofísica E Ingeniería de Tejidos, Universidad Autónoma Metropolitana, Unidad Iztapalapa. San Rafael Atlixco 186, Col. Vicentina, México City09340, México
| |
Collapse
|
15
|
Abstract
Intra-islet communication via electrical, paracrine and autocrine signals, is highly dependent on the organization of cells within the islets and is key for an adequate response to changes in blood glucose and other stimuli. In spite of the fact that relevant structural differences between mouse and human islet architectures have been described, the functional implications of these differences remain only partially understood. In this work, aiming to contribute to a better understanding of the relationship between structural and functional properties of pancreatic islets, we reconstructed human and mice islets in order to perform a structural comparison based on both morphologic and network-derived metrics. According to our results, human islets constitute a more efficient network from a connectivity viewpoint, mainly due to the higher proportion of heterotypic contacts between islet cells in comparison to mice islets.
Collapse
Affiliation(s)
- Gerardo J. Félix-Martínez
- Cátedras CONACYT, Consejo Nacional de Ciencia y Tecnología, México City, México
- Department of Electrical Engineering, Universidad Autónoma Metropolitana, México City, México
- CONTACT Gerardo J. Félix-Martínez Universidad Autónoma Metropolitana Unidad Iztapalapa. San Rafael Atlixco 186, Col. Vicentina 09340, México City, México
| | - J. R. Godínez-Fernández
- Department of Electrical Engineering, Universidad Autónoma Metropolitana, México City, México
| |
Collapse
|
16
|
Marinelli I, Fletcher PA, Sherman AS, Satin LS, Bertram R. Symbiosis of Electrical and Metabolic Oscillations in Pancreatic β-Cells. Front Physiol 2021; 12:781581. [PMID: 34925070 PMCID: PMC8682964 DOI: 10.3389/fphys.2021.781581] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [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: 09/22/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Insulin is secreted in a pulsatile pattern, with important physiological ramifications. In pancreatic β-cells, which are the cells that synthesize insulin, insulin exocytosis is elicited by pulses of elevated intracellular Ca2+ initiated by bursts of electrical activity. In parallel with these electrical and Ca2+ oscillations are oscillations in metabolism, and the periods of all of these oscillatory processes are similar. A key question that remains unresolved is whether the electrical oscillations are responsible for the metabolic oscillations via the effects of Ca2+, or whether the metabolic oscillations are responsible for the electrical oscillations due to the effects of ATP on ATP-sensitive ion channels? Mathematical modeling is a useful tool for addressing this and related questions as modeling can aid in the design of well-focused experiments that can test the predictions of particular models and subsequently be used to improve the models in an iterative fashion. In this article, we discuss a recent mathematical model, the Integrated Oscillator Model (IOM), that was the product of many years of development. We use the model to demonstrate that the relationship between calcium and metabolism in beta cells is symbiotic: in some contexts, the electrical oscillations drive the metabolic oscillations, while in other contexts it is the opposite. We provide new insights regarding these results and illustrate that what might at first appear to be contradictory data are actually compatible when viewed holistically with the IOM.
Collapse
Affiliation(s)
- Isabella Marinelli
- Centre for Systems Modelling and Quantitative Biomedicine (SMQB), University of Birmingham, Birmingham, United Kingdom
| | - Patrick A Fletcher
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, MD, United States
| | - Arthur S Sherman
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, MD, United States
| | - Leslie S Satin
- Department of Pharmacology, Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Richard Bertram
- Programs in Neuroscience and Molecular Biophysics, Department of Mathematics, Florida State University, Tallahassee, FL, United States
| |
Collapse
|
17
|
Stožer A, Skelin Klemen M, Gosak M, Križančić Bombek L, Pohorec V, Slak Rupnik M, Dolenšek J. Glucose-dependent activation, activity, and deactivation of beta cell networks in acute mouse pancreas tissue slices. Am J Physiol Endocrinol Metab 2021; 321:E305-E323. [PMID: 34280052 DOI: 10.1152/ajpendo.00043.2021] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/09/2021] [Indexed: 12/14/2022]
Abstract
Many details of glucose-stimulated intracellular calcium changes in β cells during activation, activity, and deactivation, as well as their concentration-dependence, remain to be analyzed. Classical physiological experiments indicated that in islets, functional differences between individual cells are largely attenuated, but recent findings suggest considerable intercellular heterogeneity, with some cells possibly coordinating the collective responses. To address the above with an emphasis on heterogeneity and describing the relations between classical physiological and functional network properties, we performed functional multicellular calcium imaging in mouse pancreas tissue slices over a wide range of glucose concentrations. During activation, delays to activation of cells and any-cell-to-first-responder delays are shortened, and the sizes of simultaneously responding clusters increased with increasing glucose concentrations. Exactly the opposite characterized deactivation. The frequency of fast calcium oscillations during activity increased with increasing glucose up to 12 mM glucose concentration, beyond which oscillation duration became longer, resulting in a homogenous increase in active time. In terms of functional connectivity, islets progressed from a very segregated network to a single large functional unit with increasing glucose concentration. A comparison between classical physiological and network parameters revealed that the first-responders during activation had longer active times during plateau and the most active cells during the plateau tended to deactivate later. Cells with the most functional connections tended to activate sooner, have longer active times, and deactivate later. Our findings provide a common ground for recent differing views on β cell heterogeneity and an important baseline for future studies of stimulus-secretion and intercellular coupling.NEW & NOTEWORTHY We assessed concentration-dependence in coupled β cells, degree of functional heterogeneity, and uncovered possible specialized subpopulations during the different phases of the response to glucose at the level of many individual cells. To this aim, we combined acute mouse pancreas tissue slices with functional multicellular calcium imaging over a wide range from threshold (7 mM) and physiological (8 and 9 mM) to supraphysiological (12 and 16 mM) glucose concentrations, classical physiological, and advanced network analyses.
Collapse
Affiliation(s)
- Andraž Stožer
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Marko Gosak
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | | | - Viljem Pohorec
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| |
Collapse
|
18
|
Stožer A, Paradiž Leitgeb E, Pohorec V, Dolenšek J, Križančić Bombek L, Gosak M, Skelin Klemen M. The Role of cAMP in Beta Cell Stimulus-Secretion and Intercellular Coupling. Cells 2021; 10:1658. [PMID: 34359828 PMCID: PMC8304079 DOI: 10.3390/cells10071658] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [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: 05/05/2021] [Revised: 06/18/2021] [Accepted: 06/28/2021] [Indexed: 12/22/2022] Open
Abstract
Pancreatic beta cells secrete insulin in response to stimulation with glucose and other nutrients, and impaired insulin secretion plays a central role in development of diabetes mellitus. Pharmacological management of diabetes includes various antidiabetic drugs, including incretins. The incretin hormones, glucagon-like peptide-1 and gastric inhibitory polypeptide, potentiate glucose-stimulated insulin secretion by binding to G protein-coupled receptors, resulting in stimulation of adenylate cyclase and production of the secondary messenger cAMP, which exerts its intracellular effects through activation of protein kinase A or the guanine nucleotide exchange protein 2A. The molecular mechanisms behind these two downstream signaling arms are still not fully elucidated and involve many steps in the stimulus-secretion coupling cascade, ranging from the proximal regulation of ion channel activity to the central Ca2+ signal and the most distal exocytosis. In addition to modifying intracellular coupling, the effect of cAMP on insulin secretion could also be at least partly explained by the impact on intercellular coupling. In this review, we systematically describe the possible roles of cAMP at these intra- and inter-cellular signaling nodes, keeping in mind the relevance for the whole organism and translation to humans.
Collapse
Affiliation(s)
- Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Lidija Križančić Bombek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| |
Collapse
|
19
|
Sluga N, Postić S, Sarikas S, Huang YC, Stožer A, Slak Rupnik M. Dual Mode of Action of Acetylcholine on Cytosolic Calcium Oscillations in Pancreatic Beta and Acinar Cells In Situ. Cells 2021; 10:1580. [PMID: 34201461 PMCID: PMC8305080 DOI: 10.3390/cells10071580] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 05/14/2021] [Revised: 06/08/2021] [Accepted: 06/19/2021] [Indexed: 12/13/2022] Open
Abstract
Cholinergic innervation in the pancreas controls both the release of digestive enzymes to support the intestinal digestion and absorption, as well as insulin release to promote nutrient use in the cells of the body. The effects of muscarinic receptor stimulation are described in detail for endocrine beta cells and exocrine acinar cells separately. Here we describe morphological and functional criteria to separate these two cell types in situ in tissue slices and simultaneously measure their response to ACh stimulation on cytosolic Ca2+ oscillations [Ca2+]c in stimulatory glucose conditions. Our results show that both cell types respond to glucose directly in the concentration range compatible with the glucose transporters they express. The physiological ACh concentration increases the frequency of glucose stimulated [Ca2+]c oscillations in both cell types and synchronizes [Ca2+]c oscillations in acinar cells. The supraphysiological ACh concentration further increases the oscillation frequency on the level of individual beta cells, inhibits the synchronization between these cells, and abolishes oscillatory activity in acinar cells. We discuss possible mechanisms leading to the observed phenomena.
Collapse
Affiliation(s)
- Nastja Sluga
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia; (N.S.); (A.S.)
| | - Sandra Postić
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (S.P.); (S.S.); (Y.-C.H.)
| | - Srdjan Sarikas
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (S.P.); (S.S.); (Y.-C.H.)
| | - Ya-Chi Huang
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (S.P.); (S.S.); (Y.-C.H.)
| | - Andraž Stožer
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia; (N.S.); (A.S.)
| | - Marjan Slak Rupnik
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia; (N.S.); (A.S.)
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (S.P.); (S.S.); (Y.-C.H.)
- Alma Mater Europaea, European Center Maribor, 2000 Maribor, Slovenia
| |
Collapse
|
20
|
Ivanov PC. The New Field of Network Physiology: Building the Human Physiolome. Front Netw Physiol 2021; 1:711778. [PMID: 36925582 PMCID: PMC10013018 DOI: 10.3389/fnetp.2021.711778] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 12/22/2022]
Affiliation(s)
- Plamen Ch Ivanov
- Keck Laboratory for Network Physiology, Department of Physics, Boston University, Boston, MA, United States.,Harvard Medical School and Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA, United States.,Bulgarian Academy of Sciences, Institute of Solid State Physics, Sofia, Bulgaria
| |
Collapse
|