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Cheng PC, Cheng RC, Huang RC. Glutamate-Evoked Ca2+ Responses in the Rat Suprachiasmatic Nucleus: Involvement of Na+/K+-ATPase and Na+/Ca2+-Exchanger. Int J Mol Sci 2023; 24:ijms24076444. [PMID: 37047417 PMCID: PMC10095050 DOI: 10.3390/ijms24076444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/22/2023] [Accepted: 03/28/2023] [Indexed: 03/31/2023] Open
Abstract
Glutamate mediates photic entrainment of the central clock in the suprachiasmatic nucleus (SCN) by evoking intracellular Ca2+ signaling mechanisms. However, the detailed mechanisms of glutamate-evoked Ca2+ signals are not entirely clear. Here, we used a ratiometric Ca2+ and Na+ imaging technique to investigate glutamate-evoked Ca2+ responses. The comparison of Ca2+ responses to glutamate (100 μM) and high (20 mM) K+ solution indicated slower Ca2+ clearance, along with rebound Ca2+ suppression for glutamate-evoked Ca2+ transients. Increasing the length of exposure time in glutamate, but not in 20 mM K+, slowed Ca2+ clearance and increased rebound Ca2+ suppression, a result correlated with glutamate-induced Na+ loads. The rebound Ca2+ suppression was abolished by ouabain, monensin, Na+-free solution, or nimodipine, suggesting an origin of activated Na+/K+-ATPase (NKA) by glutamate-induced Na+ loads. Ouabain or Na+-free solution also slowed Ca2+ clearance, apparently by retarding Na+/Ca2+-exchanger (NCX)-mediated Ca2+ extrusion. Together, our results indicated the involvement of glutamate-induced Na+ loads, NKA, and NCX in shaping the Ca2+ response to glutamate. Nevertheless, in the absence of external Na+ (NMDG substituted), Ca2+ clearance was still slower for the Ca2+ response to glutamate than for 20 mM K+, suggesting participation of additional Ca2+ handlers to the slower Ca2+ clearance under this condition.
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Wang H, Jin Y, Wang Y, Wang X, Yu W, Jiang X. Rotenone Induces Hepatotoxicity in Rats by Activating the Mitochondrial Pathway of Apoptosis. Toxicol Mech Methods 2022; 32:510-517. [DOI: 10.1080/15376516.2022.2049940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Huan Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
| | - Yinzhu Jin
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
| | - Yao Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
| | - Xuewei Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
| | - Wenhui Yu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
- Institute of Chinese Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
| | - Xiaowen Jiang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, China
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Marchini M, Ashkin MR, Bellini M, Sun MMG, Workentine ML, Okuyan HM, Krawetz R, Beier F, Rolian C. A Na +/K + ATPase Pump Regulates Chondrocyte Differentiation and Bone Length Variation in Mice. Front Cell Dev Biol 2022; 9:708384. [PMID: 34970538 PMCID: PMC8712571 DOI: 10.3389/fcell.2021.708384] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 11/04/2021] [Indexed: 11/23/2022] Open
Abstract
The genetic and developmental mechanisms involved in limb formation are relatively well documented, but how these mechanisms are modulated by changes in chondrocyte physiology to produce differences in limb bone length remains unclear. Here, we used high throughput RNA sequencing (RNAseq) to probe the developmental genetic basis of variation in limb bone length in Longshanks, a mouse model of experimental evolution. We find that increased tibia length in Longshanks is associated with altered expression of a few key endochondral ossification genes such as Npr3, Dlk1, Sox9, and Sfrp1, as well reduced expression of Fxyd2, a facultative subunit of the cell membrane-bound Na+/K+ ATPase pump (NKA). Next, using murine tibia and cell cultures, we show a dynamic role for NKA in chondrocyte differentiation and in bone length regulation. Specifically, we show that pharmacological inhibition of NKA disrupts chondrocyte differentiation, by upregulating expression of mesenchymal stem cell markers (Prrx1, Serpina3n), downregulation of chondrogenesis marker Sox9, and altered expression of extracellular matrix genes (e.g., collagens) associated with proliferative and hypertrophic chondrocytes. Together, Longshanks and in vitro data suggest a broader developmental and evolutionary role of NKA in regulating limb length diversity.
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Affiliation(s)
- Marta Marchini
- Department of Anatomy and Cell Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Mitchell R Ashkin
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Melina Bellini
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Margaret Man-Ger Sun
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Matthew Lloyd Workentine
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Hamza Malik Okuyan
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Roman Krawetz
- Department of Anatomy and Cell Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Frank Beier
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Campbell Rolian
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
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Plante AE, Rao VP, Rizzo MA, Meredith AL. Comparative Ca 2+ channel contributions to intracellular Ca 2+ levels in the circadian clock. Biophys Rep (N Y) 2021; 1:100005. [PMID: 35330949 PMCID: PMC8942421 DOI: 10.1016/j.bpr.2021.100005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/08/2021] [Indexed: 11/22/2022]
Abstract
Circadian rhythms in mammals are coordinated by the central clock in the brain, located in the suprachiasmatic nucleus (SCN). Multiple molecular and cellular signals display a circadian variation within SCN neurons, including intracellular Ca2+, but the mechanisms are not definitively established. SCN cytosolic Ca2+ levels exhibit a peak during the day, when both action potential firing and Ca2+ channel activity are increased, and are decreased at night, correlating with a reduction in firing rate. In this study, we employ a single-color fluorescence anisotropy reporter (FLARE), Venus FLARE-Cameleon, and polarization inverted selective-plane illumination microscopy to measure rhythmic changes in cytosolic Ca2+ in SCN neurons. Using this technique, the Ca2+ channel subtypes contributing to intracellular Ca2+ at the peak and trough of the circadian cycle were assessed using a pharmacological approach with Ca2+ channel inhibitors. Peak (218 ± 16 nM) and trough (172 ± 13 nM) Ca2+ levels were quantified, indicating a 1.3-fold circadian variance in Ca2+ concentration. Inhibition of ryanodine-receptor-mediated Ca2+ release produced a larger relative decrease in cytosolic Ca2+ at both time points compared to voltage-gated Ca2+channels. These results support the hypothesis that circadian Ca2+ rhythms in SCN neurons are predominantly driven by intracellular Ca2+ channels, although not exclusively so. The study provides a foundation for future experiments to probe Ca2+ signaling in a dynamic biological context using FLAREs.
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Affiliation(s)
- Amber E. Plante
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Vishnu P. Rao
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Megan A. Rizzo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea L. Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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Lin HY, Huang RC. Glycolytic metabolism and activation of Na + pumping contribute to extracellular acidification in the central clock of the suprachiasmatic nucleus: Differential glucose sensitivity and utilization between oxidative and non-oxidative glycolytic pathways. Biomed J 2021; 45:143-154. [PMID: 35341719 PMCID: PMC9133309 DOI: 10.1016/j.bj.2021.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 11/03/2020] [Revised: 02/02/2021] [Accepted: 02/07/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The central clock of the suprachiasmatic nucleus (SCN) controls the metabolism of glucose and is sensitive to glucose shortage. However, it is only beginning to be understood how metabolic signals such as glucose availability regulate the SCN physiology. We previously showed that the ATP-sensitive K+ channel plays a glucose-sensing role in regulating SCN neuronal firing at times of glucose shortage. Nevertheless, it is unknown whether the energy-demanding Na+/K+-ATPase (NKA) is also sensitive to glucose availability. Furthermore, we recently showed that the metabolically active SCN constantly extrudes H+ to acidify extracellular pH (pHe). This study investigated whether the standing acidification is associated with Na+ pumping activity, energy metabolism, and glucose utilization, and whether glycolysis- and mitochondria-fueled NKAs may be differentially sensitive to glucose shortage. METHODS Double-barreled pH-selective microelectrodes were used to determine the pHe in the SCN in hypothalamic slices. RESULTS NKA inhibition with K+-free (0-K+) solution rapidly and reversibly alkalinized the pHe, an effect abolished by ouabain. Mitochondrial inhibition with cyanide acidified the pHe but did not inhibit 0-K+-induced alkalinization. Glycolytic inhibition with iodoacetate alkalinized the pHe, completely blocked cyanide-induced acidification, and nearly completely blocked 0-K+-induced alkalinization. The results indicate that glycolytic metabolism and activation of Na+ pumping contribute to the standing acidification. Glucoprivation also alkalinized the pHe, nearly completely eliminated cyanide-induced acidification, but only partially reduced 0-K+-induced alkalinization. In contrast, hypoglycemia preferentially and partially blocked cyanide-induced acidification. The result indicates sensitivity to glucose shortage for the mitochondria-associated oxidative glycolytic pathway. CONCLUSION Glycolytic metabolism and activation of glycolysis-fueled NKA Na+ pumping activity contribute to the standing acidification in the SCN. Furthermore, the oxidative and non-oxidative glycolytic pathways differ in their glucose sensitivity and utilization, with the oxidative glycolytic pathway susceptible to glucose shortage, and the non-oxidative glycolytic pathway able to maintain Na+ pumping even in glucoprivation.
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Affiliation(s)
- Hsin-Yi Lin
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Rong-Chi Huang
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan; Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
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