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Phosphatases control PKA-dependent functional microdomains at the outer mitochondrial membrane. Proc Natl Acad Sci U S A 2018; 115:E6497-E6506. [PMID: 29941564 PMCID: PMC6048485 DOI: 10.1073/pnas.1806318115] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The selective phosphorylation of spatially distinct PKA targets is key for the pleiotropy of the cAMP cascade. This characteristic of the pathway is currently attributed to the ability of phosphodiesterases or adenylate cyclases to create subcellular sites (microdomains) where the concentration of cAMP is distinct from that of the surrounding areas. The role of phosphatases in this process has not been tested. Here we show that limited access of phosphatases to the PKA targets present at the outer mitochondrial membrane generates distinct microdomains of PKA phosphorylated proteins despite there being no differences in the local cAMP levels. These results describe an alternative mechanism capable of generating functional cAMP/PKA-dependent microdomains and may be extrapolated to the compartmentalization of other kinase-dependent events. Evidence supporting the heterogeneity in cAMP and PKA signaling is rapidly accumulating and has been largely attributed to the localization or activity of adenylate cyclases, phosphodiesterases, and A-kinase–anchoring proteins in different cellular subcompartments. However, little attention has been paid to the possibility that, despite homogeneous cAMP levels, a major heterogeneity in cAMP/PKA signaling could be generated by the spatial distribution of the final terminators of this cascade, i.e., the phosphatases. Using FRET-based sensors to monitor cAMP and PKA-dependent phosphorylation in the cytosol and outer mitochondrial membrane (OMM) of primary rat cardiomyocytes, we demonstrate that comparable cAMP increases in these two compartments evoke higher levels of PKA-dependent phosphorylation in the OMM. This difference is most evident for small, physiological increases of cAMP levels and with both OMM-located probes and endogenous OMM proteins. We demonstrate that this disparity depends on differences in the rates of phosphatase-dependent dephosphorylation of PKA targets in the two compartments. Furthermore, we show that the activity of soluble phosphatases attenuates PKA-driven activation of the cAMP response element-binding protein while concurrently enhancing PKA-dependent mitochondrial elongation. We conclude that phosphatases can sculpt functionally distinct cAMP/PKA domains even in the absence of gradients or microdomains of this messenger. We present a model that accounts for these unexpected results in which the degree of PKA-dependent phosphorylation is dictated by both the subcellular distribution of the phosphatases and the different accessibility of membrane-bound and soluble phosphorylated substrates to the cytosolic enzymes.
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Pozdniakova S, Ladilov Y. Functional Significance of the Adcy10-Dependent Intracellular cAMP Compartments. J Cardiovasc Dev Dis 2018; 5:E29. [PMID: 29751653 PMCID: PMC6023465 DOI: 10.3390/jcdd5020029] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/04/2018] [Accepted: 05/09/2018] [Indexed: 12/13/2022] Open
Abstract
Mounting evidence confirms the compartmentalized structure of evolutionarily conserved 3'⁻5'-cyclic adenosine monophosphate (cAMP) signaling, which allows for simultaneous participation in a wide variety of physiological functions and ensures specificity, selectivity and signal strength. One important player in cAMP signaling is soluble adenylyl cyclase (sAC). The intracellular localization of sAC allows for the formation of unique intracellular cAMP microdomains that control various physiological and pathological processes. This review is focused on the functional role of sAC-produced cAMP. In particular, we examine the role of sAC-cAMP in different cellular compartments, such as cytosol, nucleus and mitochondria.
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Affiliation(s)
- Sofya Pozdniakova
- Institute of Gender in Medicine, Center for Cardiovascular Research, Charite, 10115 Berlin, Germany.
- DZHK (German Center for Cardiovascular Research), Berlin Partner Site, 10115 Berlin, Germany.
| | - Yury Ladilov
- Institute of Gender in Medicine, Center for Cardiovascular Research, Charite, 10115 Berlin, Germany.
- DZHK (German Center for Cardiovascular Research), Berlin Partner Site, 10115 Berlin, Germany.
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Agarwal SR, Gratwohl J, Cozad M, Yang PC, Clancy CE, Harvey RD. Compartmentalized cAMP Signaling Associated With Lipid Raft and Non-raft Membrane Domains in Adult Ventricular Myocytes. Front Pharmacol 2018; 9:332. [PMID: 29740315 PMCID: PMC5925456 DOI: 10.3389/fphar.2018.00332] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/21/2018] [Indexed: 11/23/2022] Open
Abstract
Aim: Confining cAMP production to discrete subcellular locations makes it possible for this ubiquitous second messenger to elicit unique functional responses. Yet, factors that determine how and where the production of this diffusible signaling molecule occurs are incompletely understood. The fluid mosaic model originally proposed that signal transduction occurs through random interactions between proteins diffusing freely throughout the plasma membrane. However, it is now known that the movement of membrane proteins is restricted, suggesting that the plasma membrane is segregated into distinct microdomains where different signaling proteins can be concentrated. In this study, we examined what role lipid raft and non-raft membrane domains play in compartmentation of cAMP signaling in adult ventricular myocytes. Methods and Results: The freely diffusible fluorescence resonance energy transfer-based biosensor Epac2-camps was used to measure global cytosolic cAMP responses, while versions of the probe targeted to lipid raft (Epac2-MyrPalm) and non-raft (Epac2-CAAX) domains were used to monitor local cAMP production near the plasma membrane. We found that β-adrenergic receptors, which are expressed in lipid raft and non-raft domains, produce cAMP responses near the plasma membrane that are distinctly different from those produced by E-type prostaglandin receptors, which are expressed exclusively in non-raft domains. We also found that there are differences in basal cAMP levels associated with lipid raft and non-raft domains, and that this can be explained by differences in basal adenylyl cyclase activity associated with each of these membrane environments. In addition, we found evidence that phosphodiesterases 2, 3, and 4 work together in regulating cAMP activity associated with both lipid raft and non-raft domains, while phosphodiesterase 3 plays a more prominent role in the bulk cytoplasmic compartment. Conclusion: These results suggest that different membrane domains contribute to the formation of distinct pools of cAMP under basal conditions as well as following receptor stimulation in adult ventricular myocytes.
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Affiliation(s)
- Shailesh R Agarwal
- Department of Pharmacology, University of Nevada, Reno, Reno, NV, United States
| | - Jackson Gratwohl
- Department of Pharmacology, University of Nevada, Reno, Reno, NV, United States
| | - Mia Cozad
- Department of Pharmacology, University of Nevada, Reno, Reno, NV, United States
| | - Pei-Chi Yang
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Robert D Harvey
- Department of Pharmacology, University of Nevada, Reno, Reno, NV, United States
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Johnstone TB, Agarwal SR, Harvey RD, Ostrom RS. cAMP Signaling Compartmentation: Adenylyl Cyclases as Anchors of Dynamic Signaling Complexes. Mol Pharmacol 2018; 93:270-276. [PMID: 29217670 PMCID: PMC5820540 DOI: 10.1124/mol.117.110825] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 12/04/2017] [Indexed: 11/22/2022] Open
Abstract
It is widely accepted that cAMP signaling is compartmentalized within cells. However, our knowledge of how receptors, cAMP signaling enzymes, effectors, and other key proteins form specific signaling complexes to regulate specific cell responses is limited. The multicomponent nature of these systems and the spatiotemporal dynamics involved as proteins interact and move within a cell make cAMP responses highly complex. Adenylyl cyclases, the enzymatic source of cAMP production, are key starting points for understanding cAMP compartments and defining the functional signaling complexes. Three basic elements are required to form a signaling compartment. First, a localized signal is generated by a G protein-coupled receptor paired to one or more of the nine different transmembrane adenylyl cyclase isoforms that generate the cAMP signal in the cytosol. The diffusion of cAMP is subsequently limited by several factors, including expression of any number of phosphodiesterases (of which there are 24 genes plus spice variants). Finally, signal response elements are differentially localized to respond to cAMP produced within each locale. A-kinase-anchoring proteins, of which there are 43 different isoforms, facilitate this by targeting protein kinase A to specific substrates. Thousands of potential combinations of these three elements are possible in any given cell type, making the characterization of cAMP signaling compartments daunting. This review will focus on what is known about how cells organize cAMP signaling components as well as identify the unknowns. We make an argument for adenylyl cyclases being central to the formation and maintenance of these signaling complexes.
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Affiliation(s)
- Timothy B Johnstone
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (T.B.J., R.S.O.); and Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno Nevada (S.R.A., R.D.H.)
| | - Shailesh R Agarwal
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (T.B.J., R.S.O.); and Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno Nevada (S.R.A., R.D.H.)
| | - Robert D Harvey
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (T.B.J., R.S.O.); and Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno Nevada (S.R.A., R.D.H.)
| | - Rennolds S Ostrom
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (T.B.J., R.S.O.); and Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno Nevada (S.R.A., R.D.H.)
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Hu HH, Deng H, Ling S, Sun H, Kenakin T, Liang X, Fang Y. Chemical genomic analysis of GPR35 signaling. Integr Biol (Camb) 2018; 9:451-463. [PMID: 28425521 DOI: 10.1039/c7ib00005g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
GPR35, a family A orphan G protein-coupled receptor, has been implicated in inflammatory, neurological, and cardiovascular diseases. However, not much is known about the signaling and functions of GPR35. We performed a label-free kinome short hairpin RNA screen and identified a putative signaling network of GPR35 in HT-29 cells, some of which was validated using gene expression, biochemical and cellular assays. The results showed that GPR35 induced hypoxia-inducible factor 1α, and was involved in synaptic transmission, sensory perception, the immune system, and morphogenetic processes. Collectively, our data suggest that GPR35 may play an important role in response to hypoxic stress and be a potential target for the treatment of inflammatory, cardiovascular, and neurological disorders.
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Affiliation(s)
- Heidi Haibei Hu
- Biochemical Technologies, Corning R&D Corporation, Corning Incorporated, Corning, NY 14831, USA.
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56
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Leroy J, Vandecasteele G, Fischmeister R. Cyclic AMP signaling in cardiac myocytes. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2017.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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57
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Musheshe N, Schmidt M, Zaccolo M. cAMP: From Long-Range Second Messenger to Nanodomain Signalling. Trends Pharmacol Sci 2017; 39:209-222. [PMID: 29289379 DOI: 10.1016/j.tips.2017.11.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022]
Abstract
How cAMP generates hormone-specific effects has been debated for many decades. Fluorescence resonance energy transfer (FRET)-based sensors for cAMP allow real-time imaging of the second messenger in intact cells with high spatiotemporal resolution. This technology has made it possible to directly demonstrate that cAMP signals are compartmentalised. The details of such signal compartmentalisation are still being uncovered, and recent findings reveal a previously unsuspected submicroscopic heterogeneity of intracellular cAMP. A model is emerging where specificity depends on compartmentalisation and where the physiologically relevant signals are those that occur within confined nanodomains, rather than bulk changes in cytosolic cAMP. These findings subvert the classical notion of cAMP signalling and provide a new framework for the development of targeted therapeutic approaches.
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Affiliation(s)
- Nshunge Musheshe
- Department of Molecular Pharmacology, University of Groningen, The Netherlands; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Martina Schmidt
- Department of Molecular Pharmacology, University of Groningen, The Netherlands; Groningen Research Institute for Asthma and COPD, GRIAC, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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58
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Agarwal SR, Miyashiro K, Latt H, Ostrom RS, Harvey RD. Compartmentalized cAMP responses to prostaglandin EP 2 receptor activation in human airway smooth muscle cells. Br J Pharmacol 2017; 174:2784-2796. [PMID: 28603838 DOI: 10.1111/bph.13904] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/25/2017] [Accepted: 06/05/2017] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Previous studies indicate that prostaglandin EP2 receptors selectively couple to AC2 in non-lipid raft domains of airway smooth muscle (ASM) cells, where they regulate specific cAMP-dependent responses. The goal of the present study was to identify the cellular microdomains where EP2 receptors stimulate cAMP production. EXPERIMENTAL APPROACH FRET-based cAMP biosensors were targeted to different subcellular locations of primary human ASM cells. The Epac2-camps biosensor, which expresses throughout the cell, was used to measure bulk cytoplasmic responses. Epac2-MyrPalm and Epac2-CAAX were used to measure responses associated with lipid raft and non-raft regions of the plasma membrane respectively. Epac2-NLS was used to monitor responses at the nucleus. KEY RESULTS Activation of AC with forskolin or β2 -adrenoceptors with isoprenaline increased cAMP in all subcellular locations. Activation of EP2 receptors with butaprost produced cAMP responses that were most readily detected by the non-raft and nuclear sensors, but only weakly detected by the cytosolic sensor and not detected at all by the lipid raft sensor. Exposure to rolipram, a PDE4 inhibitor, unmasked the ability of EP2 receptors to increase cAMP levels associated with lipid raft domains. Overexpression of AC2 selectively increased EP2 receptor-stimulated production of cAMP in non-raft membrane domains. CONCLUSIONS AND IMPLICATIONS EP2 receptor activation of AC2 leads to cAMP production in non-raft and nuclear compartments of human ASMs, while β2 adrenoceptor signalling is broadly detected across microdomains. The activity of PDE4 appears to play a role in maintaining the integrity of compartmentalized EP2 receptor responses in these cells.
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Affiliation(s)
- Shailesh R Agarwal
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Kathryn Miyashiro
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Htun Latt
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Rennolds S Ostrom
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Robert D Harvey
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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59
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Lu FM, Hilgemann DW. Na/K pump inactivation, subsarcolemmal Na measurements, and cytoplasmic ion turnover kinetics contradict restricted Na spaces in murine cardiac myocytes. J Gen Physiol 2017; 149:727-749. [PMID: 28606910 PMCID: PMC5496509 DOI: 10.1085/jgp.201711780] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/23/2017] [Indexed: 11/20/2022] Open
Abstract
The Na/K pump exports cytoplasmic Na ions while importing K ions, and its activity is thought to be affected by restricted intracellular Na diffusion in cardiac myocytes. Lu and Hilgemann find instead that the pump can enter an inactivated state and that inactivation can be relieved by cytoplasmic Na. Decades ago, it was proposed that Na transport in cardiac myocytes is modulated by large changes in cytoplasmic Na concentration within restricted subsarcolemmal spaces. Here, we probe this hypothesis for Na/K pumps by generating constitutive transsarcolemmal Na flux with the Na channel opener veratridine in whole-cell patch-clamp recordings. Using 25 mM Na in the patch pipette, pump currents decay strongly during continuous activation by extracellular K (τ, ∼2 s). In contradiction to depletion hypotheses, the decay becomes stronger when pump currents are decreased by hyperpolarization. Na channel currents are nearly unchanged by pump activity in these conditions, and conversely, continuous Na currents up to 0.5 nA in magnitude have negligible effects on pump currents. These outcomes are even more pronounced using 50 mM Li as a cytoplasmic Na congener. Thus, the Na/K pump current decay reflects mostly an inactivation mechanism that immobilizes Na/K pump charge movements, not cytoplasmic Na depletion. When channel currents are increased beyond 1 nA, models with unrestricted subsarcolemmal diffusion accurately predict current decay (τ ∼15 s) and reversal potential shifts observed for Na, Li, and K currents through Na channels opened by veratridine, as well as for Na, K, Cs, Li, and Cl currents recorded in nystatin-permeabilized myocytes. Ion concentrations in the pipette tip (i.e., access conductance) track without appreciable delay the current changes caused by sarcolemmal ion flux. Importantly, cytoplasmic mixing volumes, calculated from current decay kinetics, increase and decrease as expected with osmolarity changes (τ >30 s). Na/K pump current run-down over 20 min reflects a failure of pumps to recover from inactivation. Simulations reveal that pump inactivation coupled with Na-activated recovery enhances the rapidity and effectivity of Na homeostasis in cardiac myocytes. In conclusion, an autoregulatory mechanism enhances cardiac Na/K pump activity when cytoplasmic Na rises and suppresses pump activity when cytoplasmic Na declines.
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Affiliation(s)
- Fang-Min Lu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
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Di Benedetto G, Gerbino A, Lefkimmiatis K. Shaping mitochondrial dynamics: The role of cAMP signalling. Biochem Biophys Res Commun 2017; 500:65-74. [PMID: 28501614 DOI: 10.1016/j.bbrc.2017.05.041] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 05/07/2017] [Indexed: 12/25/2022]
Abstract
In recent years, our idea of mitochondria evolved from "mere" energy and metabolite producers to key regulators of many cellular functions. In order to preserve and protect their functional status, these organelles engage a number of dynamic processes that allow them to decrease accumulated burden and maintain their homeostasis. Indeed, mitochondria can unite (fusion), divide (fission), position themselves strategically in the cell (motility/trafficking) and if irreversibly damaged or dysfunctional eliminated (mitophagy). These dynamic processes can be controlled both by mitochondrial and cellular signalling pathways, hence allowing mitochondria to tune their function to the cellular needs. Among the regulatory mechanisms, reversible phosphorylation downstream the cyclic AMP (cAMP) signalling cascade was shown to deeply influence mitochondrial dynamics. This review explores the emerging evidence suggesting that cAMP is a key player in the orchestration of mitochondrial fusion/fission, motility and mitophagy, extending the repertoire of this second messenger, which is now recognised as a major regulator of mitochondrial homeostasis.
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Affiliation(s)
- Giulietta Di Benedetto
- Neuroscience Institute, Italian National Research Council (CNR), Venetian Institute of Molecular Medicine, 35131, Padova, Italy
| | - Andrea Gerbino
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy
| | - Konstantinos Lefkimmiatis
- Neuroscience Institute, Italian National Research Council (CNR), Venetian Institute of Molecular Medicine, 35131, Padova, Italy.
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61
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Lohse C, Bock A, Maiellaro I, Hannawacker A, Schad LR, Lohse MJ, Bauer WR. Experimental and mathematical analysis of cAMP nanodomains. PLoS One 2017; 12:e0174856. [PMID: 28406920 PMCID: PMC5391016 DOI: 10.1371/journal.pone.0174856] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 03/16/2017] [Indexed: 12/13/2022] Open
Abstract
In their role as second messengers, cyclic nucleotides such as cAMP have a variety of intracellular effects. These complex tasks demand a highly organized orchestration of spatially and temporally confined cAMP action which should be best achieved by compartmentalization of the latter. A great body of evidence suggests that cAMP compartments may be established and maintained by cAMP degrading enzymes, e.g. phosphodiesterases (PDEs). However, the molecular and biophysical details of how PDEs can orchestrate cAMP gradients are entirely unclear. In this paper, using fusion proteins of cAMP FRET-sensors and PDEs in living cells, we provide direct experimental evidence that the cAMP concentration in the vicinity of an individual PDE molecule is below the detection limit of our FRET sensors (<100nM). This cAMP gradient persists in crude cytosol preparations. We developed mathematical models based on diffusion-reaction equations which describe the creation of nanocompartments around a single PDE molecule and more complex spatial PDE arrangements. The analytically solvable equations derived here explicitly determine how the capability of a single PDE, or PDE complexes, to create a nanocompartment depend on the cAMP degradation rate, the diffusive mobility of cAMP, and geometrical and topological parameters. We apply these generic models to our experimental data and determine the diffusive mobility and degradation rate of cAMP. The results obtained for these parameters differ by far from data in literature for free soluble cAMP interacting with PDE. Hence, restricted cAMP diffusion in the vincinity of PDE is necessary to create cAMP nanocompartments in cells.
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Affiliation(s)
- Christian Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Computer Assisted Clinical Medicine, University of Heidelberg, Heidelberg, Germany
| | - Andreas Bock
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Isabella Maiellaro
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Annette Hannawacker
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Lothar R. Schad
- Computer Assisted Clinical Medicine, University of Heidelberg, Heidelberg, Germany
| | - Martin J. Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Comprehensive Heart Failure Center, University of Würzburg, Würzburg, Germany
- * E-mail:
| | - Wolfgang R. Bauer
- Comprehensive Heart Failure Center, University of Würzburg, Würzburg, Germany
- Department of Medicine I, University Hospital Würzburg, Würzburg, Germany
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Abstract
The universal second messengers cyclic nucleotides 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) play central roles in cardiovascular function and disease. They act in discrete, functionally relevant subcellular microdomains which regulate, for example, calcium cycling and excitation-contraction coupling. Such localized cAMP and cGMP signals have been difficult to measure using conventional biochemical techniques. Recent years have witnessed the advent of live cell imaging techniques which allow visualization of these functionally relevant second messengers with unprecedented spatial and temporal resolution at cellular, subcellular and tissue levels. In this review, we discuss these new imaging techniques and give examples how they are used to visualize cAMP and cGMP in physiological and pathological settings to better understand cardiovascular function and disease. Two primary techniques include the use of Förster resonance energy transfer (FRET) based cyclic nucleotide biosensors and nanoscale scanning ion conductance microscopy (SICM). These methods can provide deep mechanistic insights into compartmentalized cAMP and cGMP signaling.
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Affiliation(s)
- Filip Berisha
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of General and Interventional Cardiology, University Heart Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany.
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Chen YC, Chen Q, Zhang T, Wang W, Fan X. Versatile tissue lasers based on high-Q Fabry-Pérot microcavities. LAB ON A CHIP 2017; 17:538-548. [PMID: 28098320 PMCID: PMC5289748 DOI: 10.1039/c6lc01457g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Biolasers are an emerging technology for next generation biochemical detection and clinical applications. Progress has recently been made to achieve lasing from biomolecules and single living cells. Tissues, which consist of cells embedded in an extracellular matrix, mimic more closely the actual complex biological environment in a living body and therefore are of more practical significance. Here, we developed a highly versatile tissue laser platform, in which tissues stained with fluorophores are sandwiched in a high-Q Fabry-Pérot microcavity. Distinct lasing emissions from muscle and adipose tissues stained respectively with fluorescein isothiocyanate (FITC) and boron-dipyrromethene (BODIPY), and hybrid muscle/adipose tissue with dual staining were achieved with a threshold of only ∼10 μJ mm-2. Additionally, we investigated how the tissue structure/geometry, tissue thickness, and staining dye concentration affect the tissue laser. Lasing emission from FITC conjugates (FITC-phalloidin) that specifically target F-actin in muscle tissues was also realized. It is further found that, despite the large fluorescence spectral overlap between FITC and BODIPY in tissues, their lasing emissions could be clearly distinguished and controlled due to their narrow lasing bands and different lasing thresholds, thus enabling highly multiplexed detection. Our tissue laser platform can be broadly applicable to various types of tissues/diseases. It provides a new tool for a wide range of biological and biomedical applications, such as diagnostics/screening of tissues and identification/monitoring of biological transformations in tissue engineering.
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Affiliation(s)
- Yu-Cheng Chen
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI 48109, USA.
| | - Qiushu Chen
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI 48109, USA.
| | - Tingting Zhang
- Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, 79 Yingze Street, Taiyuan 030024, PR China
| | - Wenjie Wang
- Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, 79 Yingze Street, Taiyuan 030024, PR China
| | - Xudong Fan
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI 48109, USA. and Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, 79 Yingze Street, Taiyuan 030024, PR China
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65
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Bedioune I, Bobin P, Leroy J, Fischmeister R, Vandecasteele G. Cyclic Nucleotide Phosphodiesterases and Compartmentation in Normal and Diseased Heart. MICRODOMAINS IN THE CARDIOVASCULAR SYSTEM 2017. [DOI: 10.1007/978-3-319-54579-0_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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66
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Pendin D, Greotti E, Lefkimmiatis K, Pozzan T. Exploring cells with targeted biosensors. J Gen Physiol 2016; 149:1-36. [PMID: 28028123 PMCID: PMC5217087 DOI: 10.1085/jgp.201611654] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 10/26/2016] [Accepted: 12/01/2016] [Indexed: 01/10/2023] Open
Abstract
Cellular signaling networks are composed of multiple pathways, often interconnected, that form complex networks with great potential for cross-talk. Signal decoding depends on the nature of the message as well as its amplitude, temporal pattern, and spatial distribution. In addition, the existence of membrane-bound organelles, which are both targets and generators of messages, add further complexity to the system. The availability of sensors that can localize to specific compartments in live cells and monitor their targets with high spatial and temporal resolution is thus crucial for a better understanding of cell pathophysiology. For this reason, over the last four decades, a variety of strategies have been developed, not only to generate novel and more sensitive probes for ions, metabolites, and enzymatic activity, but also to selectively deliver these sensors to specific intracellular compartments. In this review, we summarize the principles that have been used to target organic or protein sensors to different cellular compartments and their application to cellular signaling.
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Affiliation(s)
- Diana Pendin
- Neuroscience Institute, National Research Council, Padua Section, 35121 Padua, Italy.,Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Elisa Greotti
- Neuroscience Institute, National Research Council, Padua Section, 35121 Padua, Italy.,Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Konstantinos Lefkimmiatis
- Neuroscience Institute, National Research Council, Padua Section, 35121 Padua, Italy.,Venetian Institute of Molecular Medicine, 35129 Padua, Italy
| | - Tullio Pozzan
- Neuroscience Institute, National Research Council, Padua Section, 35121 Padua, Italy.,Venetian Institute of Molecular Medicine, 35129 Padua, Italy.,Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
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Brandenburg S, Kohl T, Williams GSB, Gusev K, Wagner E, Rog-Zielinska EA, Hebisch E, Dura M, Didié M, Gotthardt M, Nikolaev VO, Hasenfuss G, Kohl P, Ward CW, Lederer WJ, Lehnart SE. Axial tubule junctions control rapid calcium signaling in atria. J Clin Invest 2016; 126:3999-4015. [PMID: 27643434 DOI: 10.1172/jci88241] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/09/2016] [Indexed: 11/17/2022] Open
Abstract
The canonical atrial myocyte (AM) is characterized by sparse transverse tubule (TT) invaginations and slow intracellular Ca2+ propagation but exhibits rapid contractile activation that is susceptible to loss of function during hypertrophic remodeling. Here, we have identified a membrane structure and Ca2+-signaling complex that may enhance the speed of atrial contraction independently of phospholamban regulation. This axial couplon was observed in human and mouse atria and is composed of voluminous axial tubules (ATs) with extensive junctions to the sarcoplasmic reticulum (SR) that include ryanodine receptor 2 (RyR2) clusters. In mouse AM, AT structures triggered Ca2+ release from the SR approximately 2 times faster at the AM center than at the surface. Rapid Ca2+ release correlated with colocalization of highly phosphorylated RyR2 clusters at AT-SR junctions and earlier, more rapid shortening of central sarcomeres. In contrast, mice expressing phosphorylation-incompetent RyR2 displayed depressed AM sarcomere shortening and reduced in vivo atrial contractile function. Moreover, left atrial hypertrophy led to AT proliferation, with a marked increase in the highly phosphorylated RyR2-pS2808 cluster fraction, thereby maintaining cytosolic Ca2+ signaling despite decreases in RyR2 cluster density and RyR2 protein expression. AT couplon "super-hubs" thus underlie faster excitation-contraction coupling in health as well as hypertrophic compensatory adaptation and represent a structural and metabolic mechanism that may contribute to contractile dysfunction and arrhythmias.
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Yang PC, Boras BW, Jeng MT, Docken SS, Lewis TJ, McCulloch AD, Harvey RD, Clancy CE. A Computational Modeling and Simulation Approach to Investigate Mechanisms of Subcellular cAMP Compartmentation. PLoS Comput Biol 2016; 12:e1005005. [PMID: 27409243 PMCID: PMC4943723 DOI: 10.1371/journal.pcbi.1005005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/26/2016] [Indexed: 11/18/2022] Open
Abstract
Subcellular compartmentation of the ubiquitous second messenger cAMP has been widely proposed as a mechanism to explain unique receptor-dependent functional responses. How exactly compartmentation is achieved, however, has remained a mystery for more than 40 years. In this study, we developed computational and mathematical models to represent a subcellular sarcomeric space in a cardiac myocyte with varying detail. We then used these models to predict the contributions of various mechanisms that establish subcellular cAMP microdomains. We used the models to test the hypothesis that phosphodiesterases act as functional barriers to diffusion, creating discrete cAMP signaling domains. We also used the models to predict the effect of a range of experimentally measured diffusion rates on cAMP compartmentation. Finally, we modeled the anatomical structures in a cardiac myocyte diad, to predict the effects of anatomical diffusion barriers on cAMP compartmentation. When we incorporated experimentally informed model parameters to reconstruct an in silico subcellular sarcomeric space with spatially distinct cAMP production sites linked to caveloar domains, the models predict that under realistic conditions phosphodiesterases alone were insufficient to generate significant cAMP gradients. This prediction persisted even when combined with slow cAMP diffusion. When we additionally considered the effects of anatomic barriers to diffusion that are expected in the cardiac myocyte dyadic space, cAMP compartmentation did occur, but only when diffusion was slow. Our model simulations suggest that additional mechanisms likely contribute to cAMP gradients occurring in submicroscopic domains. The difference between the physiological and pathological effects resulting from the production of cAMP may be a function of appropriate compartmentation of cAMP signaling. Therefore, understanding the contribution of factors that are responsible for coordinating the spatial and temporal distribution of cAMP at the subcellular level could be important for developing new strategies for the prevention or treatment of unfavorable responses associated with different disease states. Subcellular compartmentation of the ubiquitous second messenger cAMP has been widely proposed as a mechanism to explain how this one signaling molecule produces unique receptor-dependent functional responses. But, how exactly compartmentation occurs, is unknown. This is because there has been no way to measure the regulation and movement of cAMP in cells with intact subcellular structures. In this study, we applied novel computational approaches to predict whether PDE activity alone or in conjunction with restricted diffusion is sufficient to produce cAMP gradients in submicroscopic signaling domains. We also used the models to test the effect of a range of experimentally measured diffusion rates on cAMP compartmentation. Our simulations suggest that PDE activity alone is not sufficient to explain compartmentation, but if diffusion of cAMP is limited by potential factors such as molecular crowding, PKA buffering, and anatomical barriers, then compartmentation is predicted to occur.
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Affiliation(s)
- Pei-Chi Yang
- Department of Pharmacology, University of California Davis, Davis, California, United States of America
| | - Britton W. Boras
- Department of Biomedical Engineering, University of California San Diego, La Jolla, California, United States of America
| | - Mao-Tsuen Jeng
- Department of Pharmacology, University of California Davis, Davis, California, United States of America
| | - Steffen S. Docken
- Department of Pharmacology, University of California Davis, Davis, California, United States of America
- Department of Mathematics, University of California Davis, Davis, California, United States of America
| | - Timothy J. Lewis
- Department of Mathematics, University of California Davis, Davis, California, United States of America
- * E-mail: (TJL); (ADM); (RDH); (CEC)
| | - Andrew D. McCulloch
- Department of Biomedical Engineering, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (TJL); (ADM); (RDH); (CEC)
| | - Robert D. Harvey
- Department of Pharmacology, Center for Molecular Medicine, School of Medicine, University of Nevada Reno, Reno, Nevada, United States of America
- * E-mail: (TJL); (ADM); (RDH); (CEC)
| | - Colleen E. Clancy
- Department of Pharmacology, University of California Davis, Davis, California, United States of America
- * E-mail: (TJL); (ADM); (RDH); (CEC)
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69
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A Computational Modeling and Simulation Approach to Investigate Mechanisms of Subcellular cAMP Compartmentation. PLoS Comput Biol 2016. [DOI: 10.1371/journal.pcbi.1005005 pcompbiol-d-16-00287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Richards M, Lomas O, Jalink K, Ford KL, Vaughan-Jones RD, Lefkimmiatis K, Swietach P. Intracellular tortuosity underlies slow cAMP diffusion in adult ventricular myocytes. Cardiovasc Res 2016; 110:395-407. [PMID: 27089919 PMCID: PMC4872880 DOI: 10.1093/cvr/cvw080] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/11/2016] [Indexed: 12/20/2022] Open
Abstract
Aims 3′,5′-Cyclic adenosine monophosphate (cAMP) signals in the heart are often confined to concentration microdomains shaped by cAMP diffusion and enzymatic degradation. While the importance of phosphodiesterases (degradative enzymes) in sculpting cAMP microdomains is well established in cardiomyocytes, less is known about cAMP diffusivity (DcAMP) and factors affecting it. Many earlier studies have reported fast diffusivity, which argues against sharply defined microdomains. Methods and results [cAMP] dynamics in the cytoplasm of adult rat ventricular myocytes were imaged using a fourth generation genetically encoded FRET-based sensor. The [cAMP]-response to the addition and removal of isoproterenol (β-adrenoceptor agonist) quantified the rates of cAMP synthesis and degradation. To obtain a read out of DcAMP, a stable [cAMP] gradient was generated using a microfluidic device which delivered agonist to one half of the myocyte only. After accounting for phosphodiesterase activity, DcAMP was calculated to be 32 µm2/s; an order of magnitude lower than in water. Diffusivity was independent of the amount of cAMP produced. Saturating cAMP-binding sites with the analogue 6-Bnz-cAMP did not accelerate DcAMP, arguing against a role of buffering in restricting cAMP mobility. cAMP diffused at a comparable rate to chemically unrelated but similar sized molecules, arguing for a common physical cause of restricted diffusivity. Lower mitochondrial density and order in neonatal cardiac myocytes allowed for faster diffusion, demonstrating the importance of mitochondria as physical barriers to cAMP mobility. Conclusion In adult cardiac myocytes, tortuosity due to physical barriers, notably mitochondria, restricts cAMP diffusion to levels that are more compatible with microdomain signalling.
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Affiliation(s)
- Mark Richards
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Oliver Lomas
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Kees Jalink
- Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Kerrie L Ford
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Richard D Vaughan-Jones
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Konstantinos Lefkimmiatis
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK BHF Centre of Research Excellence, Oxford
| | - Pawel Swietach
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
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