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Machado JD, Montenegro P, Domínguez N. Quantal Release Analysis of Electrochemically Active Molecules Using Single-Cell Amperometry. Methods Mol Biol 2023; 2565:203-211. [PMID: 36205896 DOI: 10.1007/978-1-0716-2671-9_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Single-cell amperometry is a powerful technique that permits the detection of electrochemically active transmitters, such as catecholamines, histamine, or serotonin, released by exocytosis from secretory cells.Amperometry has two main characteristics that make it ideal for the study of exocytosis at the single-cell level with single-vesicle resolution quantal release. (i) It is noninvasive. The carbon fiber microelectrode can be carefully positioned on plasma membrane of a single cell, allowing the detection of the oxidation current of the secreted molecules. (ii) High temporal resolution and sensitivity. Exocytosis can be monitored with a real-time resolution that allows the determination of the kinetics release with an attomol detection sensitivity, which ensures an accurate calculation of the amount of transmitter released.Here, we compile some recommendations and advices to perform amperometry quantal analysis.
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Affiliation(s)
- José David Machado
- Dpto. Medicina Física y Farmacología, Facultad de Ciencias de la Salud, Medicina, Universidad de La Laguna, La Laguna, Tenerife, Spain.
| | - Pablo Montenegro
- Pharmacology Unit, Department of Physical Medicine and Pharmacology, Medical School, Universidad de La Laguna, Tenerife, Spain
| | - Natalia Domínguez
- Dpto. Bioquímica, Microbiología, Biología Celular y Genética, Facultad de Ciencias, Sección Biología, Universidad de La Laguna, Tenerife, Spain
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Gomis Perez C, Dudzinski NR, Rouches M, Landajuela A, Machta B, Zenisek D, Karatekin E. Rapid propagation of membrane tension at retinal bipolar neuron presynaptic terminals. SCIENCE ADVANCES 2022; 8:eabl4411. [PMID: 34985955 DOI: 10.1126/sciadv.abl4411] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Many cellular activities, such as cell migration, cell division, phagocytosis, and exo-endocytosis, generate and are regulated by membrane tension gradients. Membrane tension gradients drive membrane flows, but there is controversy over how rapidly plasma membrane flow can relax tension gradients. Here, we show that membrane tension can propagate rapidly or slowly, spanning orders of magnitude in speed, depending on the cell type. In a neuronal terminal specialized for rapid synaptic vesicle turnover, membrane tension equilibrates within seconds. By contrast, membrane tension does not propagate in neuroendocrine adrenal chromaffin cells secreting catecholamines. Stimulation of exocytosis causes a rapid, global decrease in the synaptic terminal membrane tension, which recovers slowly due to endocytosis. Thus, membrane flow and tension equilibration may be adapted to distinct membrane recycling requirements.
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Affiliation(s)
- Carolina Gomis Perez
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
| | - Natasha R Dudzinski
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
| | - Mason Rouches
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Systems Biology Institute, Yale University, West Haven, CT, USA
| | - Ane Landajuela
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
| | - Benjamin Machta
- Systems Biology Institute, Yale University, West Haven, CT, USA
- Department of Physics, Yale University, New Haven, CT, USA
| | - David Zenisek
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
- Kavli Institute for Neuroscience, Yale University, New Haven, CT, USA
- Department of Neuroscience, Yale University, New Haven, CT, USA
- Department of Ophthalmology and Visual Sciences, Yale University, New Haven, CT, USA
| | - Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Université de Paris, SPPIN-Saints-Pères Paris Institute for the Neurosciences, Centre National de la Recherche Scientifique (CNRS), Paris F-75006, France
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Glucagon-like peptide-1 receptor controls exocytosis in chromaffin cells by increasing full-fusion events. Cell Rep 2021; 36:109609. [PMID: 34433018 DOI: 10.1016/j.celrep.2021.109609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/02/2021] [Accepted: 08/04/2021] [Indexed: 11/21/2022] Open
Abstract
Agonists for glucagon-like-peptide-1 receptor (GLP-1R) are currently used for the treatment of type 2 diabetes and obesity. Their benefits have been centered on pancreas and hypothalamus, but their roles in other organ systems are not well understood. We studied the action of GLP-1R on secretions of adrenal medulla. Exendin-4, a synthetic analog of GLP-1, increases the synthesis and the release of catecholamines (CAs) by increasing cyclic AMP (cAMP) production, without apparent participation of cAMP-regulated guanine nucleotide exchange factor (Epac). Exendin-4, when incubated for 24 h, increases CA synthesis by promoting the activation of tyrosine hydroxylase. Short incubation (20 min) increases the quantum size of exocytotic events by switching exocytosis from partial to full fusion. Our results give a strong support to the role of GLP-1 in the fine control of exocytosis.
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GIPC2 is an endocrine-specific tumor suppressor gene for both sporadic and hereditary tumors of RET- and SDHB-, but not VHL-associated clusters of pheochromocytoma/paraganglioma. Cell Death Dis 2021; 12:444. [PMID: 33947839 PMCID: PMC8096975 DOI: 10.1038/s41419-021-03731-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 04/10/2021] [Accepted: 04/14/2021] [Indexed: 12/16/2022]
Abstract
Pheochromocytoma/paraganglioma (PPGL) is an endocrine tumor of the chromaffin cells in the adrenal medulla or the paraganglia. Currently, about 70% of PPGLs can be explained by germline or somatic mutations in several broadly expressed susceptibility genes including RET, VHL, and SDHB, while for the remaining, mainly sporadic cases, the pathogenesis is still unclear. Even for known susceptible genes, how mutations in these mostly ubiquitous genes result in tissue-specific pathogenesis remains unanswered, and why RET-mutated tumors almost always occur in the adrenal while SDHB-mutated tumors mostly occur extra-adrenal remains a mystery. By analyzing 22 sporadic PPGLs using SNP 6.0 genotyping arrays combined with expression profiling of 4 normal and 4 tumor tissues, we identified GIPC2, a gene located at 1p31.1 with preferential expression in adrenal and inducible by adrenal glucocorticoid, as a novel putative tumor suppressor gene for PPGLs. Copy number deletion and GIPC2 promoter hypermethylation but not GIPC2 mutation, accompanied with reduced GIPC2 expression, were observed in 39 of 55 PPGLs in our cohort. Examination of a published expression database consisting of 188 PPGLs found little GIPC2 expression in Cluster 1A (SDHx-associated) and Cluster 2A (NF1/RET-associated) tumors, but less pronounced reduction of GIPC2 expression in Cluster 1B (VHL-associated) and Cluster 2B/2C tumors. GIPC2 induced p27, suppressed MAPK/ERK and HIF-1ɑ pathways as well as cancer cell proliferation. Overexpressing GIPC2 in PC12 cells inhibited tumor growth in nude mice. We found GIPC2 interacted with the nucleoprotein NONO and both proteins regulated p27 transcription through the same GGCC box on p27 promoter. Significantly, low expression of both GIPC2 and p27 was associated with shorter disease-free survival time of PPGLs patients in the TCGA database. We found that PPGL-causing mutations in RET and in SDHB could lead to primary rat adrenal chromaffin cell proliferation, ERK activation, and p27 downregulation, all requiring downregulating GIPC2. Notably, the RET-mutant effect required the presence of dexamethasone while the SDHB-mutant effect required its absence, providing a plausible explanation for the tumor location preference. In contrast, the PPGL-predisposing VHL mutations had no effect on proliferation and GIPC2 expression but caused p53 downregulation and reduced apoptosis in chromaffin cells compared with wild-type VHL. Thus, our study raises the importance of cortical hormone in PPGL development, and GIPC2 as a novel tumor suppressor provides a unified molecular mechanism for the tumorigenesis of both sporadic and hereditary tumors of Clusters 1A and 2A concerning SDHB and RET, but not tumors of Cluster 1B concerning VHL and other clusters.
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Abstract
Over the last four decades, chromaffin cells originating from the adrenal medulla have been probably one of the most popular cell models to study neurosecretion at the molecular level. Accordingly, numerous seminal discoveries in the field, including the characterization of role of the cytoskeleton, fusogenic lipids, and soluble N-ethylmaleimide-sensitivefactor attachment protein receptor (SNARE) proteins, have been made using this model. In this chapter, we describe a standard method currently used to isolate and culture bovine chromaffin cells, and we illustrate a catecholamine secretion assay based on the successive transformation of adrenaline into adrenochrome and adrenolutine for fluorescence measurements. We also provide some guidelines for efficient cell recovery and for the use of this assay in the laboratory.
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Measurements of Compensatory Endocytosis by Antibody Internalization and Quantification of Endocytic Vesicle Distribution in Adrenal Chromaffin Cells. Methods Mol Biol 2020. [PMID: 33222126 DOI: 10.1007/978-1-0716-1044-2_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Plasma membrane proteins are amenable to endocytosis assays since they are easily labeled by reagents applied in the extracellular medium. This has been widely exploited to study constitutive endocytosis or ligand-induced receptor endocytosis. Compensatory endocytosis is the mechanism by which components of secretory vesicles are retrieved after vesicle fusion with the plasma membrane in response to cell stimulation and a rise in intracellular calcium. Luminal membrane proteins from secretory vesicles are therefore transiently exposed at the plasma membrane. Here, we described an antibody-based method to monitor compensatory endocytosis in chromaffin cells and present an image-based analysis to quantify endocytic vesicles distribution.
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González-Santana A, Castañeyra L, Baz-Dávila R, Estévez-Herrera J, Domínguez N, Méndez-López I, Padín JF, Castañeyra A, Machado JD, Ebert SN, Borges R. Adrenergic chromaffin cells are adrenergic even in the absence of epinephrine. J Neurochem 2019; 152:299-314. [PMID: 31677273 DOI: 10.1111/jnc.14904] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 11/30/2022]
Abstract
Adrenal chromaffin cells release epinephrine (EPI) and norepinephrine (NE) into the bloodstream as part of the homeostatic response to situations like stress. Here we utilized EPI-deficient mice generated by knocking out (KO) the phenylethanolamine N-methyltransferase (Pnmt) gene. These Pnmt-KO mice were bred to homozygosis but displayed no major phenotype. The lack of EPI was partially compensated by an increase in NE, suggesting that EPI storage was optimized in adrenergic cells. Electron microscopy showed that despite the lack of EPI, chromaffin granules retain their shape and general appearance. This indicate that granules from adrenergic or noradrenergic cells preserve their characteristics even though they contain only NE. Acute insulin injection largely reduced the EPI content in wild-type animals, with a minimal reduction in NE, whereas there was only a partial reduction in NE content in Pnmt-KO mice. The analysis of exocytosis by amperometry revealed a reduction in the quantum size (-30%) and Imax (-21%) of granules in KO cells relative to the wild-type granules, indicating a lower affinity of NE for the granule matrix of adrenergic cells. As amperometry cannot distinguish between adrenergic or noradrenergic cells, it would suggest even a larger reduction in the affinity for the matrix. Therefore, our results demonstrate that adrenergic cells retain their structural characteristics despite the almost complete absence of EPI. Furthermore, the chromaffin granule matrix from adrenergic cells is optimized to accumulate EPI, with NE being a poor substitute. Open Science: This manuscript was awarded with the Open Materials Badge For more information see: https://cos.io/our-services/open-science-badges/.
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Affiliation(s)
| | - Leandro Castañeyra
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
| | - Rebeca Baz-Dávila
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
| | | | - Natalia Domínguez
- INTEGRARE, Généthon, Inserm, Univ Evry, Université Paris-Saclay, Evry, France
| | - Iago Méndez-López
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, Madrid, Spain
| | - J Fernando Padín
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, Madrid, Spain.,Departamento Ciencias Médicas (Farmacología), Facultad de Medicina, Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Agustín Castañeyra
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Tenerife, Spain
| | - José-David Machado
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
| | - Steven N Ebert
- Division of Metabolic and Cardiovascular Sciences, Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Ricardo Borges
- Unidad de Farmacología, Facultad de Medicina, Universidad de la Laguna, Tenerife, Spain
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Martinez-Espinosa PL, Yang C, Gonzalez-Perez V, Xia XM, Lingle CJ. Knockout of the BK β2 subunit abolishes inactivation of BK currents in mouse adrenal chromaffin cells and results in slow-wave burst activity. ACTA ACUST UNITED AC 2015; 144:275-95. [PMID: 25267913 PMCID: PMC4178941 DOI: 10.1085/jgp.201411253] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chromaffin cells from mice lacking the BK β2 subunit show decreased action potential firing during current injection but an increase in spontaneous burst firing. Rat and mouse adrenal medullary chromaffin cells (CCs) express an inactivating BK current. This inactivation is thought to arise from the assembly of up to four β2 auxiliary subunits (encoded by the kcnmb2 gene) with a tetramer of pore-forming Slo1 α subunits. Although the physiological consequences of inactivation remain unclear, differences in depolarization-evoked firing among CCs have been proposed to arise from the ability of β2 subunits to shift the range of BK channel activation. To investigate the role of BK channels containing β2 subunits, we generated mice in which the gene encoding β2 was deleted (β2 knockout [KO]). Comparison of proteins from wild-type (WT) and β2 KO mice allowed unambiguous demonstration of the presence of β2 subunit in various tissues and its coassembly with the Slo1 α subunit. We compared current properties and cell firing properties of WT and β2 KO CCs in slices and found that β2 KO abolished inactivation, slowed action potential (AP) repolarization, and, during constant current injection, decreased AP firing. These results support the idea that the β2-mediated shift of the BK channel activation range affects repetitive firing and AP properties. Unexpectedly, CCs from β2 KO mice show an increased tendency toward spontaneous burst firing, suggesting that the particular properties of BK channels in the absence of β2 subunits may predispose to burst firing.
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Affiliation(s)
- Pedro L Martinez-Espinosa
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Chengtao Yang
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Xiao-Ming Xia
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
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Chalcones as positive allosteric modulators of α7 nicotinic acetylcholine receptors: A new target for a privileged structure. Eur J Med Chem 2014; 86:724-39. [DOI: 10.1016/j.ejmech.2014.09.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 12/26/2022]
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