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Theparambil SM, Begum G, Rose CR. pH regulating mechanisms of astrocytes: A critical component in physiology and disease of the brain. Cell Calcium 2024; 120:102882. [PMID: 38631162 DOI: 10.1016/j.ceca.2024.102882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 03/28/2024] [Accepted: 03/28/2024] [Indexed: 04/19/2024]
Abstract
Strict homeostatic control of pH in both intra- and extracellular compartments of the brain is fundamentally important, primarily due to the profound impact of free protons ([H+]) on neuronal activity and overall brain function. Astrocytes, crucial players in the homeostasis of various ions in the brain, actively regulate their intracellular [H+] (pHi) through multiple membrane transporters and carbonic anhydrases. The activation of astroglial pHi regulating mechanisms also leads to corresponding alterations in the acid-base status of the extracellular fluid. Notably, astrocyte pH regulators are modulated by various neuronal signals, suggesting their pivotal role in regulating brain acid-base balance in both health and disease. This review presents the mechanisms involved in pH regulation in astrocytes and discusses their potential impact on extracellular pH under physiological conditions and in brain disorders. Targeting astrocytic pH regulatory mechanisms represents a promising therapeutic approach for modulating brain acid-base balance in diseases, offering a potential critical contribution to neuroprotection.
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Affiliation(s)
- Shefeeq M Theparambil
- Faculty of Health and Medicine, Department of Biomedical and Life Sciences, Lancaster University, Lancaster, LA1 4YW, Lancaster, UK.
| | - Gulnaz Begum
- Department of Neurology, The Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
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Nohesara S, Abdolmaleky HM, Thiagalingam S. Potential for New Therapeutic Approaches by Targeting Lactate and pH Mediated Epigenetic Dysregulation in Major Mental Diseases. Biomedicines 2024; 12:457. [PMID: 38398057 PMCID: PMC10887322 DOI: 10.3390/biomedicines12020457] [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: 01/29/2024] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 02/25/2024] Open
Abstract
Multiple lines of evidence have shown that lactate-mediated pH alterations in the brains of patients with neuropsychiatric diseases such as schizophrenia (SCZ), Alzheimer's disease (AD) and autism may be attributed to mitochondrial dysfunction and changes in energy metabolism. While neuronal activity is associated with reduction in brain pH, astrocytes are responsible for rebalancing the pH to maintain the equilibrium. As lactate level is the main determinant of brain pH, neuronal activities are impacted by pH changes due to the binding of protons (H+) to various types of proteins, altering their structure and function in the neuronal and non-neuronal cells of the brain. Lactate and pH could affect diverse types of epigenetic modifications, including histone lactylation, which is linked to histone acetylation and DNA methylation. In this review, we discuss the importance of pH homeostasis in normal brain function, the role of lactate as an essential epigenetic regulatory molecule and its contributions to brain pH abnormalities in neuropsychiatric diseases, and shed light on lactate-based and pH-modulating therapies in neuropsychiatric diseases by targeting epigenetic modifications. In conclusion, we attempt to highlight the potentials and challenges of translating lactate-pH-modulating therapies to clinics for the treatment of neuropsychiatric diseases.
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Affiliation(s)
- Shabnam Nohesara
- Department of Medicine (Biomedical Genetics), Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA;
| | - Hamid Mostafavi Abdolmaleky
- Department of Medicine (Biomedical Genetics), Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA;
- Nutrition/Metabolism Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Sam Thiagalingam
- Department of Medicine (Biomedical Genetics), Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA;
- Department of Pathology & Laboratory Medicine, Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA
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Andreyanov M, Heinrich R, Berlin S. Design of Ultrapotent Genetically Encoded Inhibitors of Kv4.2 for Gating Neural Plasticity. J Neurosci 2024; 44:e2295222023. [PMID: 38154956 PMCID: PMC10869153 DOI: 10.1523/jneurosci.2295-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 11/05/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023] Open
Abstract
The Kv4.2 potassium channel plays established roles in neuronal excitability, while also being implicated in plasticity. Current means to study the roles of Kv4.2 are limited, motivating us to design a genetically encoded membrane tethered Heteropodatoxin-2 (MetaPoda). We find that MetaPoda is an ultrapotent and selective gating-modifier of Kv4.2. We narrow its site of contact with the channel to two adjacent residues within the voltage sensitive domain (VSD) and, with docking simulations, suggest that the toxin binds the VSD from within the membrane. We also show that MetaPoda does not require an external linker of the channel for its activity. In neurons (obtained from female and male rat neonates), MetaPoda specifically, and potently, inhibits all Kv4 currents, leaving all other A-type currents unaffected. Inhibition of Kv4 in hippocampal neurons does not promote excessive excitability, as is expected from a simple potassium channel blocker. We do find that MetaPoda's prolonged expression (1 week) increases expression levels of the immediate early gene cFos and prevents potentiation. These findings argue for a major role of Kv4.2 in facilitating plasticity of hippocampal neurons. Lastly, we show that our engineering strategy is suitable for the swift engineering of another potent Kv4.2-selective membrane-tethered toxin, Phrixotoxin-1, denoted MetaPhix. Together, we provide two uniquely potent genetic tools to study Kv4.2 in neuronal excitability and plasticity.
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Affiliation(s)
- Michael Andreyanov
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa 3525433, Israel
| | - Ronit Heinrich
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa 3525433, Israel
| | - Shai Berlin
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa 3525433, Israel
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Ho JQ, Verghese J, Abramowitz MK. Serum bicarbonate levels and gait abnormalities in older adults: a cross-sectional study. Sci Rep 2022; 12:9171. [PMID: 35654910 PMCID: PMC9163170 DOI: 10.1038/s41598-022-12907-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 05/18/2022] [Indexed: 11/17/2022] Open
Abstract
Metabolic acidosis is associated with impaired physical function in patients with chronic kidney disease (CKD) and older adults. However, whether acidosis is associated with gait abnormalities has received little attention. In a cohort of 323 community-dwelling adults ≥ 65 years old who underwent quantitative gait analysis, we examined associations of serum bicarbonate with eight individual gait variables. After multivariable adjustment, participants in the lowest bicarbonate tertile (< 25 mEq/L) had 8.6 cm/s slower speed (95% confidence interval [CI] 3.2–13.9), 7.9 cm shorter stride length (95% CI 3.5–12.2), and 0.03 s longer double support time (95% CI 0.002–0.1) compared with those in the middle tertile (25–27 mEq/L). Furthermore, lower bicarbonate levels were associated with more severe gait abnormalities in a graded manner. After further adjustment for possible mediating factors, associations were attenuated but remained significant. Among participants with CKD, associations were of similar or greater magnitude compared with those without CKD. Factor analysis was performed to synthesize the individual gait variables into unifying domains: among the pace, rhythm, and variability domains, lower serum bicarbonate was associated with worse performance in pace. In sum, lower serum bicarbonate was independently associated with worse performance on several quantitative measures of gait among older adults.
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Affiliation(s)
- Jim Q Ho
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Ullmann 615, Bronx, NY, 10461, USA
| | - Joe Verghese
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Ullmann 615, Bronx, NY, 10461, USA.,Department of Neurology, Albert Einstein College of Medicine, Bronx, NY, USA.,Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Matthew K Abramowitz
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Ullmann 615, Bronx, NY, 10461, USA. .,Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA. .,Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY, USA. .,Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, USA.
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Liu S, Chen R. [Acid-sensing ion channels differentially affect ictal-like and non-ictal-like epileptic activities of mouse hippocampal pyramidal neurons in acidotic extracellular pH]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2020; 40:972-980. [PMID: 32895149 DOI: 10.12122/j.issn.1673-4254.2020.07.09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the effects of acid-sensing ion channels (ASICs) on electrophysiological epileptic activities of mouse hippocampal pyramidal neurons in the extracellular acidotic condition. METHODS We investigated effects of extracellular acidosis on epileptic activities induced by elevated extracellular K + concentration or the application of an antagonist of GABAA receptors in perfusate of mouse hippocampal slices under field potential recordings. We also tested the effects of extracellular acidosis on neuronal excitability under field potential recording and evaluated the changes in epileptic activities of the neurons in response to pharmacological inhibition of ASICs using a specific inhibitor of ASICs. RESULTS Extracellular acidosis significantly suppressed epileptic activities of the hippocampal neurons by converting ictal-like epileptic activities to non-ictal-like epileptic activities in both high [K +]o and disinhibition models, and also suppressed the intrinsic excitability of the neurons. ASICs inhibitor did not antagonize the inhibitory effect of extracellular acidosis on ictal epileptic activities and intrinsic neuronal excitability, but exacerbated non-ictal epileptic activities of the neurons in extracellular acidotic condition in both high [K+]o and disinhibition models. CONCLUSIONS ASICs can differentially modulate ictal-like and non-ictallike epileptic activities via its direct actions on excitatory neurons.
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Affiliation(s)
- Shuai Liu
- Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Rongqing Chen
- Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
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