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Olivera JF, Pizarro G. Quantal Properties of Voltage-Dependent Ca 2+ Release in Frog Skeletal Muscle Persist After Reduction of [Ca 2+] in the Sarcoplasmic Reticulum. J Membr Biol 2024; 257:37-50. [PMID: 38460011 DOI: 10.1007/s00232-024-00309-0] [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: 10/23/2023] [Accepted: 02/09/2024] [Indexed: 03/11/2024]
Abstract
In skeletal muscle, the Ca2+ release flux elicited by a voltage clamp pulse rises to an early peak that inactivates rapidly to a much lower steady level. Using a double pulse protocol the fast inactivation follows an arithmetic rule: if the conditioning depolarization is less than or equal to the test depolarization, then decay (peak minus steady level) in the conditioning release is approximately equal to suppression (unconditioned minus conditioned peak) of the test release. This is due to quantal activation by voltage, analogous to the quantal activation of IP3 receptor channels. Two mechanisms are possible. One is the existence of subsets of channels with different sensitivities to voltage. The other is that the clusters of Ca2+-gated Ryanodine Receptor (RyR) β in the parajunctional terminal cisternae might constitute the quantal units. These Ca2+-gated channels are activated by the release of Ca2+ through the voltage-gated RyR α channels. If the RyR β were at the basis of quantal release, it should be modified by strong inhibition of the primary voltage-gated release. This was attained in two ways, by sarcoplasmic reticulum (SR) Ca2+ depletion and by voltage-dependent inactivation. Both procedures reduced global Ca2+ release flux, but SR Ca2+ depletion reduced the single RyR current as well. The effect of both interventions on the quantal properties of Ca2+ release in frog skeletal muscle fibers were studied under voltage clamp. The quantal properties of release were preserved regardless of the inhibitory maneuver applied. These findings put a limit on the role of the Ca2+-activated component of release in generating quantal activation.
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Affiliation(s)
- J F Olivera
- Departamento de Biofísica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - G Pizarro
- Departamento de Biofísica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
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2
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Zheng C, Snow BE, Elia AJ, Nechanitzky R, Dominguez-Brauer C, Liu S, Tong Y, Cox MA, Focaccia E, Wakeham AC, Haight J, Tobin C, Hodgson K, Gill KT, Ma W, Berger T, Heikenwälder M, Saunders ME, Fortin J, Leung SY, Mak TW. Tumor-specific cholinergic CD4 + T lymphocytes guide immunosurveillance of hepatocellular carcinoma. Nat Cancer 2023; 4:1437-1454. [PMID: 37640929 PMCID: PMC10597839 DOI: 10.1038/s43018-023-00624-w] [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] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 07/26/2023] [Indexed: 08/31/2023]
Abstract
Cholinergic nerves are involved in tumor progression and dissemination. In contrast to other visceral tissues, cholinergic innervation in the hepatic parenchyma is poorly detected. It remains unclear whether there is any form of cholinergic regulation of liver cancer. Here, we show that cholinergic T cells curtail the development of liver cancer by supporting antitumor immune responses. In a mouse multihit model of hepatocellular carcinoma (HCC), we observed activation of the adaptive immune response and induction of two populations of CD4+ T cells expressing choline acetyltransferase (ChAT), including regulatory T cells and dysfunctional PD-1+ T cells. Tumor antigens drove the clonal expansion of these cholinergic T cells in HCC. Genetic ablation of Chat in T cells led to an increased prevalence of preneoplastic cells and exacerbated liver cancer due to compromised antitumor immunity. Mechanistically, the cholinergic activity intrinsic in T cells constrained Ca2+-NFAT signaling induced by T cell antigen receptor engagement. Without this cholinergic modulation, hyperactivated CD25+ T regulatory cells and dysregulated PD-1+ T cells impaired HCC immunosurveillance. Our results unveil a previously unappreciated role for cholinergic T cells in liver cancer immunobiology.
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Affiliation(s)
- Chunxing Zheng
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
- Centre for Oncology and Immunology, Hong Kong Science Park, Hong Kong SAR, China
| | - Bryan E Snow
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Andrew J Elia
- Tumor Immunotherapy Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Robert Nechanitzky
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | | | - Shaofeng Liu
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Yin Tong
- Centre for Oncology and Immunology, Hong Kong Science Park, Hong Kong SAR, China
- Department of Pathology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
| | - Maureen A Cox
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Enrico Focaccia
- Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Andrew C Wakeham
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Jillian Haight
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Chantal Tobin
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Kelsey Hodgson
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Kyle T Gill
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Wei Ma
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Thorsten Berger
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Mathias Heikenwälder
- Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
- The M3 Research Center, Medical Faculty Tübingen, Tübingen, Germany
| | - Mary E Saunders
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Jerome Fortin
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Suet Yi Leung
- Centre for Oncology and Immunology, Hong Kong Science Park, Hong Kong SAR, China
- Department of Pathology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
| | - Tak W Mak
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
- Centre for Oncology and Immunology, Hong Kong Science Park, Hong Kong SAR, China.
- Tumor Immunotherapy Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
- Department of Pathology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.
- Departments of Immunology and Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
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3
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Smith HA, Thillaiappan NB, Rossi AM. IP 3 receptors: An "elementary" journey from structure to signals. Cell Calcium 2023; 113:102761. [PMID: 37271052 DOI: 10.1016/j.ceca.2023.102761] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 06/06/2023]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are large tetrameric channels which sit mostly in the membrane of the endoplasmic reticulum (ER) and mediate Ca2+ release from intracellular stores in response to extracellular stimuli in almost all cells. Dual regulation of IP3Rs by IP3 and Ca2+ itself, upstream "licensing", and the arrangement of IP3Rs into small clusters in the ER membrane, allow IP3Rs to generate spatially and temporally diverse Ca2+ signals. The characteristic biphasic regulation of IP3Rs by cytosolic Ca2+ concentration underpins regenerative Ca2+ signals by Ca2+-induced Ca2+-release, while also preventing uncontrolled explosive Ca2+ release. In this way, cells can harness a simple ion such as Ca2+ as a near-universal intracellular messenger to regulate diverse cellular functions, including those with conflicting outcomes such as cell survival and cell death. High-resolution structures of the IP3R bound to IP3 and Ca2+ in different combinations have together started to unravel the workings of this giant channel. Here we discuss, in the context of recently published structures, how the tight regulation of IP3Rs and their cellular geography lead to generation of "elementary" local Ca2+ signals known as Ca2+ "puffs", which form the fundamental bottleneck through which all IP3-mediated cytosolic Ca2+ signals must first pass.
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Affiliation(s)
- Holly A Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | | | - Ana M Rossi
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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4
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Smith HA, Taylor CW. Dissociation of inositol 1,4,5-trisphosphate from IP 3 receptors contributes to termination of Ca 2+ puffs. J Biol Chem 2023; 299:102871. [PMID: 36621623 PMCID: PMC9971896 DOI: 10.1016/j.jbc.2023.102871] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/23/2022] [Accepted: 12/26/2022] [Indexed: 01/07/2023] Open
Abstract
Ca2+ puffs are brief, localized Ca2+ signals evoked by physiological stimuli that arise from the coordinated opening of a few clustered inositol 1,4,5-trisphosphate receptors (IP3Rs). However, the mechanisms that control the amplitude and termination of Ca2+ puffs are unresolved. To address these issues, we expressed SNAP-tagged IP3R3 in HEK cells without endogenous IP3Rs and used total internal reflection fluorescence microscopy to visualize the subcellular distribution of IP3Rs and the Ca2+ puffs that they evoke. We first confirmed that SNAP-IP3R3 were reliably identified and that they evoked normal Ca2+ puffs after photolysis of a caged analog of IP3. We show that increased IP3R expression caused cells to assemble more IP3R clusters, each of which contained more IP3Rs, but the mean amplitude of Ca2+ puffs (indicative of the number of open IP3Rs) was unaltered. We thus suggest that functional interactions between IP3Rs constrain the number of active IP3Rs within a cluster. Furthermore, Ca2+ puffs evoked by IP3R with reduced affinity for IP3 had undiminished amplitude, but the puffs decayed more quickly. The selective effect of reducing IP3 affinity on the decay times of Ca2+ puffs was not mimicked by exposing normal IP3R to a lower concentration of IP3. We conclude that distinct mechanisms constrain recruitment of IP3Rs during the rising phase of a Ca2+ puff and closure of IP3Rs during the falling phase, and that only the latter is affected by the rate of IP3 dissociation.
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Affiliation(s)
- Holly A Smith
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom.
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5
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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [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: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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6
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Patel S, Bootman MD, Rossi A, Rahman T, Marchant JS. Quantal leaps in understanding Ca
2+
signaling: A “Taylored” approach. Sci Signal 2022; 15:eadf0308. [DOI: 10.1126/scisignal.adf0308] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
On 2 September 2022, about 85 scientists gathered in person at Queens’ College in Cambridge, UK, for a scientific meeting to celebrate the career of Colin W. Taylor of Cambridge University upon his retirement. The meeting was organized by the authors, who are all former graduate students in the Taylor laboratory, which has been at the forefront of Ca
2+
signaling for more than 30 years.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London (UCL), Gower Street, London WC1E 6BT, UK
| | - Martin D. Bootman
- School of Life, Health and Chemical Sciences, Faculty of Science, Technology, Engineering and Mathematics, Walton Hall, Open University, Milton Keynes MK7 6AA, UK
| | - Ana Rossi
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Jonathan S. Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee WI 53226, USA
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7
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Khan S. Endoplasmic Reticulum in Metaplasticity: From Information Processing to Synaptic Proteostasis. Mol Neurobiol 2022; 59:5630-5655. [PMID: 35739409 DOI: 10.1007/s12035-022-02916-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 06/05/2022] [Indexed: 11/29/2022]
Abstract
The ER (endoplasmic reticulum) is a Ca2+ reservoir and the unique protein-synthesizing machinery which is distributed throughout the neuron and composed of multiple different structural domains. One such domain is called EMC (endoplasmic reticulum membrane protein complex), pleiotropic nature in cellular functions. The ER/EMC position inside the neurons unmasks its contribution to synaptic plasticity via regulating various cellular processes from protein synthesis to Ca2+ signaling. Since presynaptic Ca2+ channels and postsynaptic ionotropic receptors are organized into the nanodomains, thus ER can be a crucial player in establishing TMNCs (transsynaptic molecular nanocolumns) to shape efficient neural communications. This review hypothesized that ER is not only involved in stress-mediated neurodegeneration but also axon regrowth, remyelination, neurotransmitter switching, information processing, and regulation of pre- and post-synaptic functions. Thus ER might not only be a protein-synthesizing and quality control machinery but also orchestrates plasticity of plasticity (metaplasticity) within the neuron to execute higher-order brain functions and neural repair.
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Affiliation(s)
- Shumsuzzaman Khan
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA.
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