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Halaney DL, Zahedivash A, Phipps JE, Wang T, Dwelle J, Saux CJL, Asmis R, Milner TE, Feldman MD. Differences in forward angular light scattering distributions between M1 and M2 macrophages. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:115002. [PMID: 26538329 PMCID: PMC4881287 DOI: 10.1117/1.jbo.20.11.115002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 10/09/2015] [Indexed: 05/11/2023]
Abstract
The ability to distinguish macrophage subtypes noninvasively could have diagnostic potential in cancer, atherosclerosis, and diabetes, where polarized M1 and M2 macrophages play critical and often opposing roles. Current methods to distinguish macrophage subtypes rely on tissue biopsy. Optical imaging techniques based on light scattering are of interest as they can be translated into biopsy-free strategies. Because mitochondria are relatively strong subcellular light scattering centers, and M2 macrophages are known to have enhanced mitochondrial biogenesis compared to M1, we hypothesized that M1 and M2 macrophages may have different angular light scattering profiles. To test this, we developed an in vitro angle-resolved forward light scattering measurement system. We found that M1 and M2 macrophage monolayers scatter relatively unequal amounts of light in the forward direction between 1.6 deg and 3.2 deg with M2 forward scattering significantly more light than M1 at increasing angles. The ratio of forward scattering can be used to identify the polarization state of macrophage populations in culture.
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Affiliation(s)
- David L. Halaney
- University of Texas Health Science Center at San Antonio, Division of Cardiology, Department of Medicine, 7703 Floyd Curl Drive, San Antonio, Texas 78229, United States
- South Texas Veterans Health Care System, Department of Veterans Affairs, 7400 Merton Minter, San Antonio, Texas 78229, United States
| | - Aydin Zahedivash
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station C0800, Austin, Texas 78712, United States
| | - Jennifer E. Phipps
- University of Texas Health Science Center at San Antonio, Division of Cardiology, Department of Medicine, 7703 Floyd Curl Drive, San Antonio, Texas 78229, United States
| | - Tianyi Wang
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station C0800, Austin, Texas 78712, United States
| | - Jordan Dwelle
- South Texas Veterans Health Care System, Department of Veterans Affairs, 7400 Merton Minter, San Antonio, Texas 78229, United States
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station C0800, Austin, Texas 78712, United States
| | - Claude Jourdan Le Saux
- University of Texas Health Science Center at San Antonio, Division of Cardiology, Department of Medicine, 7703 Floyd Curl Drive, San Antonio, Texas 78229, United States
| | - Reto Asmis
- University of Texas Health Science Center at San Antonio, Departments of Clinical Laboratory Sciences and Biochemistry, 7703 Floyd Curl Drive, San Antonio, Texas 78229, United States
| | - Thomas E. Milner
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station C0800, Austin, Texas 78712, United States
| | - Marc D. Feldman
- University of Texas Health Science Center at San Antonio, Division of Cardiology, Department of Medicine, 7703 Floyd Curl Drive, San Antonio, Texas 78229, United States
- South Texas Veterans Health Care System, Department of Veterans Affairs, 7400 Merton Minter, San Antonio, Texas 78229, United States
- Address all correspondence to: Marc D. Feldman, E-mail:
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Phillips D, Aponte AM, French SA, Chess DJ, Balaban RS. Succinyl-CoA synthetase is a phosphate target for the activation of mitochondrial metabolism. Biochemistry 2009; 48:7140-9. [PMID: 19527071 DOI: 10.1021/bi900725c] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Succinyl-CoA synthetase (SCS) is the only mitochondrial enzyme capable of ATP production via substrate level phosphorylation in the absence of oxygen, but it also plays a key role in the citric acid cycle, ketone metabolism, and heme synthesis. Inorganic phosphate (P(i)) is a signaling molecule capable of activating oxidative phosphorylation at several sites, including NADH generation and as a substrate for ATP formation. In this study, it was shown that P(i) binds the porcine heart SCS alpha-subunit (SCSalpha) in a noncovalent manner and enhances its enzymatic activity, thereby providing a new target for P(i) activation in mitochondria. Coupling 32P labeling of intact mitochondria with SDS gel electrophoresis revealed that 32P labeling of SCSalpha was enhanced in substrate-depleted mitochondria. Using mitochondrial extracts and purified bacterial SCS (BSCS), we showed that this enhanced 32P labeling resulted from a simple binding of 32P, not covalent protein phosphorylation. The ability of SCSalpha to retain its 32P throughout the SDS denaturing gel process was unique over the entire mitochondrial proteome. In vitro studies also revealed a P(i)-induced activation of SCS activity by more than 2-fold when mitochondrial extracts and purified BSCS were incubated with millimolar concentrations of P(i). Since the level of 32P binding to SCSalpha was increased in substrate-depleted mitochondria, where the matrix P(i) concentration is increased, we conclude that SCS activation by P(i) binding represents another mitochondrial target for the P(i)-induced activation of oxidative phosphorylation and anaerobic ATP production in energy-limited mitochondria.
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Affiliation(s)
- Darci Phillips
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-1061, USA
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Bose S, French S, Evans FJ, Joubert F, Balaban RS. Metabolic network control of oxidative phosphorylation: multiple roles of inorganic phosphate. J Biol Chem 2003; 278:39155-65. [PMID: 12871940 DOI: 10.1074/jbc.m306409200] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphate (Pi) is a putative cytosolic signaling molecule in the regulation of oxidative phosphorylation. Here, by using a multiparameter monitoring system, we show that Pi controls oxidative phosphorylation in a balanced fashion, modulating both the generation of useful potential energy and the formation of ATP by F1F0-ATPase in heart and skeletal muscle mitochondria. In these studies the effect of Pi was determined on the mitochondria [NADH], NADH generating capacity, matrix pH, membrane potential, oxygen consumption, and cytochrome reduction level. Pi enhanced NADH generation and was obligatory for electron flow under uncoupled conditions. Pi oxidized cytochrome b (cyto-b) and reduced cytochrome c (cyto-c), potentially improving the coupling between the NADH free energy and the proton motive force. The apparent limitation in reducing equivalent flow between cyto-b and cyto-c in the absence of Pi was confirmed in the intact heart by using optical spectroscopic techniques under conditions with low cytosolic [Pi]. These results demonstrate that Pi signaling results in the balanced modulation of oxidative phosphorylation, by influencing both deltaGH+ generation and ATP production, which may contribute to the energy metabolism homeostasis observed in intact systems.
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Affiliation(s)
- Salil Bose
- Laboratory of Cardiac Energetics, NHLBI, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA
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Wilson RH, Thurston EL, Mitchell R. Ultrastructural transformations in bean inner mitochondrial membranes. PLANT PHYSIOLOGY 1973; 51:26-30. [PMID: 16658291 PMCID: PMC367351 DOI: 10.1104/pp.51.1.26] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The ultrastructure of inner membrane-matrix mitochondria isolated from bean (Phaseolus vulgaris) shoots was examined in different metabolic states. Gross ultrastructural transformations analogous to the condensed-to-orthodox configurational changes reported in mammalian mitochondria are observed on transistion from nonrespiring to respiring metabolism. With the induction of oxidative phosphorylation, the particles remain in the orthodox configurational state. The reverse orthodox-to-condensed configurational changes observed in mammalian preparations does not occur. Optically monitored absorbancy studies with bean particles show a substrate-supported P(i)-induced swelling under the same conditions that induce the condensed-to-orthodox ultrastructural transformation. The swelling is associated with the net uptake of K(+) and P(i) as well as a small P(i)-induced respiratory stimulation. When phosphorylation is initiated with these swollen particles, the optically monitored volume remains unchanged. Thus a positive correlation exists between the ultrastructural configuration and the osmotic volume changes, which supports the conclusion that configurational changes reflect internal osmotic adjustments.
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Affiliation(s)
- R H Wilson
- Department of Botany, University of Texas, Austin, Texas 78712
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Hanson JB. Ion transport induced by polycations and its relationship to loose coupling of corn mitochondria. PLANT PHYSIOLOGY 1972; 49:707-15. [PMID: 16658034 PMCID: PMC366038 DOI: 10.1104/pp.49.5.707] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Treatment of corn mitochondria (Zea mays L., WF9 (Tms) x M14) with polycations (protamine, pancreatic ribonuclease, or polylysine) releases acceptorless respiration if phosphate is present. Concurrently, there is extensive active swelling which is reversed when respiration is uncoupled or stopped. Mersalyl, the phosphate transport inhibitor, blocks both the release of respiration and the active swelling. Diversion of energy into phosphate transport lowers respiratory control and ADP: O ratios. This response is termed "loose coupling" in distinction to "uncoupling" in which energy is made unavailable for either transport or ATP formation. Corn mitochondria as used here are endogenously loose coupled to some extent, and show state 4 respiration linked to active transport.The action of polycations can be partially mimicked by lowering pH of the suspending medium; both give swelling in sucrose medium and increased light absorbancy. Triton X-100, a nonionic detergent, will uncouple and accentuate active swelling, but unlike polycations it will not release state 4 respiration. Calcium ion acts something like polycation in activating phosphate transport and releasing respiration, and polycation appears to block entry of Ca(2+).It is speculated that neutralization of certain negatively charged acid groups on the membranes by polycations increases permeability to solutes and decreases coulombic repulsion of phosphate in approaching transport sites. In consequence, respiration rates and active transport rates increase.
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Affiliation(s)
- J B Hanson
- Department of Botany, University of Illinois, Urbana, Illinois 61801
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