1
|
Vilas-Boas EA, Kowaltowski AJ. Mitochondrial redox state, bioenergetics, and calcium transport in caloric restriction: A metabolic nexus. Free Radic Biol Med 2024; 219:195-214. [PMID: 38677486 DOI: 10.1016/j.freeradbiomed.2024.04.234] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/22/2024] [Accepted: 04/24/2024] [Indexed: 04/29/2024]
Abstract
Mitochondria congregate central reactions in energy metabolism, many of which involve electron transfer. As such, they are expected to both respond to changes in nutrient supply and demand and also provide signals that integrate energy metabolism intracellularly. In this review, we discuss how mitochondrial bioenergetics and reactive oxygen species production is impacted by dietary interventions that change nutrient availability and impact on aging, such as calorie restriction. We also discuss how dietary interventions alter mitochondrial Ca2+ transport, regulating both mitochondrial and cytosolic processes modulated by this ion. Overall, a plethora of literature data support the idea that mitochondrial oxidants and calcium transport act as integrating signals coordinating the response to changes in nutritional supply and demand in cells, tissues, and animals.
Collapse
Affiliation(s)
- Eloisa A Vilas-Boas
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Brazil.
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil.
| |
Collapse
|
2
|
Rocha DS, Manucci AC, Bruni-Cardoso A, Kowaltowski AJ, Vilas-Boas EA. A practical and robust method to evaluate metabolic fluxes in primary pancreatic islets. Mol Metab 2024; 83:101922. [PMID: 38521184 PMCID: PMC11002748 DOI: 10.1016/j.molmet.2024.101922] [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: 01/15/2024] [Revised: 02/22/2024] [Accepted: 03/17/2024] [Indexed: 03/25/2024] Open
Abstract
OBJECTIVE Evaluation of mitochondrial oxygen consumption and ATP production is important to investigate pancreatic islet pathophysiology. Most studies use cell lines due to difficulties in measuring primary islet respiration, which requires specific equipment and consumables, is expensive and poorly reproducible. Our aim was to establish a practical method to assess primary islet metabolic fluxes using standard commercial consumables. METHODS Pancreatic islets were isolated from mice/rats, dispersed with trypsin, and adhered to pre-coated standard Seahorse or Resipher microplates. Oxygen consumption was evaluated using a Seahorse Extracellular Flux Analyzer or a Resipher Real-time Cell Analyzer. RESULTS We provide a detailed protocol with all steps to optimize islet isolation with high yield and functionality. Our method requires a few islets per replicate; both rat and mouse islets present robust basal respiration and proper response to mitochondrial modulators and glucose. The technique was validated by other functional assays, which show these cells present conserved calcium influx and insulin secretion in response to glucose. We also show that our dispersed islets maintain robust basal respiration levels, in addition to maintaining up to 89% viability after five days in dispersed cultures. Furthermore, OCRs can be measured in Seahorse analyzers and in other plate respirometry systems, using standard materials. CONCLUSIONS Overall, we established a practical and robust method to assess islet metabolic fluxes and oxidative phosphorylation, a valuable tool to uncover basic β-cell metabolic mechanisms as well as for translational investigations, such as pharmacological candidate discovery and islet transplantation protocols.
Collapse
Affiliation(s)
- Debora S Rocha
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, SP, Brazil
| | - Antonio C Manucci
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, SP, Brazil
| | | | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, SP, Brazil
| | - Eloisa A Vilas-Boas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, SP, Brazil; Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP, Brazil.
| |
Collapse
|
3
|
Ramos VM, Serna JDC, Vilas-Boas EA, Cabral-Costa JV, Cunha FM, Kataura T, Korolchuk VI, Kowaltowski AJ. Mitochondrial sodium/calcium exchanger (NCLX) regulates basal and starvation-induced autophagy through calcium signaling. FASEB J 2024; 38:e23454. [PMID: 38315457 DOI: 10.1096/fj.202301368rr] [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: 07/06/2023] [Revised: 01/09/2024] [Accepted: 01/16/2024] [Indexed: 02/07/2024]
Abstract
Mitochondria shape intracellular Ca2+ signaling through the concerted activity of Ca2+ uptake via mitochondrial calcium uniporters and efflux by Na+ /Ca2+ exchangers (NCLX). Here, we describe a novel relationship among NCLX, intracellular Ca2+ , and autophagic activity. Conditions that stimulate autophagy in vivo and in vitro, such as caloric restriction and nutrient deprivation, upregulate NCLX expression in hepatic tissue and cells. Conversely, knockdown of NCLX impairs basal and starvation-induced autophagy. Similarly, acute inhibition of NCLX activity by CGP 37157 affects bulk and endoplasmic reticulum autophagy (ER-phagy) without significant impacts on mitophagy. Mechanistically, CGP 37157 inhibited the formation of FIP200 puncta and downstream autophagosome biogenesis. Inhibition of NCLX caused decreased cytosolic Ca2+ levels, and intracellular Ca2+ chelation similarly suppressed autophagy. Furthermore, chelation did not exhibit an additive effect on NCLX inhibition of autophagy, demonstrating that mitochondrial Ca2+ efflux regulates autophagy through the modulation of Ca2+ signaling. Collectively, our results show that the mitochondrial Ca2+ extrusion pathway through NCLX is an important regulatory node linking nutrient restriction and autophagy regulation.
Collapse
Affiliation(s)
- Vitor M Ramos
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Julian D C Serna
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Eloisa A Vilas-Boas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | | | - Fernanda M Cunha
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tetsushi Kataura
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Viktor I Korolchuk
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| |
Collapse
|
4
|
Vilas-Boas EA, Cabral-Costa JV, Ramos VM, Caldeira da Silva CC, Kowaltowski AJ. Goldilocks calcium concentrations and the regulation of oxidative phosphorylation: Too much, too little, or just right. J Biol Chem 2023; 299:102904. [PMID: 36642177 PMCID: PMC9947387 DOI: 10.1016/j.jbc.2023.102904] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Calcium (Ca2+) is a key regulator in diverse intracellular signaling pathways and has long been implicated in metabolic control and mitochondrial function. Mitochondria can actively take up large amounts of Ca2+, thereby acting as important intracellular Ca2+ buffers and affecting cytosolic Ca2+ transients. Excessive mitochondrial matrix Ca2+ is known to be deleterious due to opening of the mitochondrial permeability transition pore (mPTP) and consequent membrane potential dissipation, leading to mitochondrial swelling, rupture, and cell death. Moderate Ca2+ within the organelle, on the other hand, can directly or indirectly activate mitochondrial matrix enzymes, possibly impacting on ATP production. Here, we aimed to determine in a quantitative manner if extra- or intramitochondrial Ca2+ modulates oxidative phosphorylation in mouse liver mitochondria and intact hepatocyte cell lines. To do so, we monitored the effects of more modest versus supraphysiological increases in cytosolic and mitochondrial Ca2+ on oxygen consumption rates. Isolated mitochondria present increased respiratory control ratios (a measure of oxidative phosphorylation efficiency) when incubated with low (2.4 ± 0.6 μM) and medium (22.0 ± 2.4 μM) Ca2+ concentrations in the presence of complex I-linked substrates pyruvate plus malate and α-ketoglutarate, respectively, but not complex II-linked succinate. In intact cells, both low and high cytosolic Ca2+ led to decreased respiratory rates, while ideal rates were present under physiological conditions. High Ca2+ decreased mitochondrial respiration in a substrate-dependent manner, mediated by mPTP. Overall, our results uncover a Goldilocks effect of Ca2+ on liver mitochondria, with specific "just right" concentrations that activate oxidative phosphorylation.
Collapse
Affiliation(s)
- Eloisa A Vilas-Boas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
| | - João Victor Cabral-Costa
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Vitor M Ramos
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | | | - Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
| |
Collapse
|
5
|
Vilas-Boas EA, Carlein C, Nalbach L, Almeida DC, Ampofo E, Carpinelli AR, Roma LP, Ortis F. Early Cytokine-Induced Transient NOX2 Activity Is ER Stress-Dependent and Impacts β-Cell Function and Survival. Antioxidants (Basel) 2021; 10:antiox10081305. [PMID: 34439552 PMCID: PMC8389306 DOI: 10.3390/antiox10081305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 07/18/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 01/23/2023] Open
Abstract
In type 1 diabetes (T1D) development, proinflammatory cytokines (PIC) released by immune cells lead to increased reactive oxygen species (ROS) production in β-cells. Nonetheless, the temporality of the events triggered and the role of different ROS sources remain unclear. Isolated islets from C57BL/6J wild-type (WT), NOX1 KO and NOX2 KO mice were exposed to a PIC combination. We show that cytokines increase O2•− production after 2 h in WT and NOX1 KO but not in NOX2 KO islets. Using transgenic mice constitutively expressing a genetically encoded compartment specific H2O2 sensor, we show, for the first time, a transient increase of cytosolic/nuclear H2O2 in islet cells between 4 and 5 h during cytokine exposure. The H2O2 increase coincides with the intracellular NAD(P)H decrease and is absent in NOX2 KO islets. NOX2 KO confers better glucose tolerance and protects against cytokine-induced islet secretory dysfunction and death. However, NOX2 absence does not counteract the cytokine effects in ER Ca2+ depletion, Store-Operated Calcium Entry (SOCE) increase and ER stress. Instead, the activation of ER stress precedes H2O2 production. As early NOX2-driven ROS production impacts β-cells’ function and survival during insulitis, NOX2 might be a potential target for designing therapies against early β-cell dysfunction in the context of T1D onset.
Collapse
Affiliation(s)
- Eloisa A. Vilas-Boas
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany; (E.A.V.-B.); (C.C.)
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
| | - Christopher Carlein
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany; (E.A.V.-B.); (C.C.)
| | - Lisa Nalbach
- Institute for Clinical and Experimental Surgery, Saarland University, 66424 Homburg, Germany; (L.N.); (E.A.)
| | - Davidson C. Almeida
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, 66424 Homburg, Germany; (L.N.); (E.A.)
| | - Angelo R. Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
| | - Leticia P. Roma
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany; (E.A.V.-B.); (C.C.)
- Correspondence: (L.P.R.); (F.O.); Tel.: +06841-16-16240 (L.P.R.); +55-(11)-3091-0923 (F.O.); Fax: +06841-16-16302 (L.P.R.)
| | - Fernanda Ortis
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
- Correspondence: (L.P.R.); (F.O.); Tel.: +06841-16-16240 (L.P.R.); +55-(11)-3091-0923 (F.O.); Fax: +06841-16-16302 (L.P.R.)
| |
Collapse
|