Dataset Information

The Impact of Ca²⁺ on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

ABSTRACT: The membrane-bound hemoglobin (Hb) fraction impacts red blood cell (RBC) rheology and metabolism. Therefore, Hb-RBC membrane interactions are precisely controlled. For instance, the signaling function of membrane-bound deoxy-Hb and the structure of the docking sites in the cytosolic domain of the anion exchanger 1 (AE-1) protein are well documented; however, much less is known about the interaction of Hb variants with the erythrocyte's membrane. Here, we identified factors other than O₂ availability that control Hb abundance in the membrane-bound fraction and the possible variant-specific binding selectivity of Hb to the membrane. We show that depletion of extracellular Ca²⁺ by chelators, or its omission from the extracellular medium, leads to membrane-bound Hb release into the cytosol. The removal of extracellular Ca²⁺ further triggers the redistribution of HbA0 and HbA2 variants between the membrane and the cytosol in favor of membrane-bound HbA2. Both effects are reversible and are no longer observed upon reintroduction of Ca²⁺ into the extracellular medium. Fluctuations of cytosolic Ca²⁺ also impact the pre-membrane Hb pool, resulting in the massive transfer of Hb to the cellular cytosol. We hypothesize that AE-1 is the specific membrane target and discuss the physiological outcomes and possible clinical implications of the Ca²⁺ regulation of the intracellular Hb distribution.

SUBMITTER: Livshits L

PROVIDER: S-EPMC10526966 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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The Impact of Ca<sup>2+</sup> on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

Livshits Leonid L Peretz Sari S Bogdanova Anna A Zoabi Hiba H Eitam Harel H Barshtein Gregory G Galindo Cindy C Feldman Yuri Y Pajić-Lijaković Ivana I Koren Ariel A Gassmann Max M Levin Carina C

Cells 20230915 18

The membrane-bound hemoglobin (Hb) fraction impacts red blood cell (RBC) rheology and metabolism. Therefore, Hb-RBC membrane interactions are precisely controlled. For instance, the signaling function of membrane-bound deoxy-Hb and the structure of the docking sites in the cytosolic domain of the anion exchanger 1 (AE-1) protein are well documented; however, much less is known about the interaction of Hb variants with the erythrocyte's membrane. Here, we identified factors other than O<sub>2</su ...[more]

PMID: 37759502

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Project description:BackgroundIntracellular Ca2+ modulates several microglial activities, such as proliferation, migration, phagocytosis, and inflammatory mediator secretion. Extracellular ATP, the levels of which significantly change during epileptic seizures, activates specific receptors leading to an increase of intracellular free Ca2+ concentration ([Ca2+]i). Here, we aimed to functionally characterize human microglia obtained from cortices of subjects with temporal lobe epilepsy, focusing on the Ca2+-mediated response triggered by purinergic signaling.MethodsFura-2 based fluorescence microscopy was used to measure [Ca2+]i in primary cultures of human microglial cells obtained from surgical specimens. The perforated patch-clamp technique, which preserves the cytoplasmic milieu, was used to measure ATP-evoked Ca2+-dependent whole-cell currents.ResultsIn human microglia extracellular ATP evoked [Ca2+]i increases depend on Ca2+ entry from the extracellular space and on Ca2+ mobilization from intracellular compartments. Extracellular ATP also induced a transient fivefold potentiation of the total transmembrane current, which was completely abolished when [Ca2+]i increases were prevented by removing external Ca2+ and using an intracellular Ca2+ chelator. TRAM-34, a selective KCa3.1 blocker, significantly reduced the ATP-induced current potentiation but did not abolish it. The removal of external Cl- in the presence of TRAM-34 further lowered the ATP-evoked effect. A direct comparison between the ATP-evoked mean current potentiation and mean Ca2+ transient amplitude revealed a linear correlation. Treatment of microglial cells with LPS for 48 h did not prevent the ATP-induced Ca2+ mobilization but completely abolished the ATP-mediated current potentiation. The absence of the Ca2+-evoked K+ current led to a less sustained ATP-evoked Ca2+ entry, as shown by the faster Ca2+ transient kinetics observed in LPS-treated microglia.ConclusionsOur study confirms a functional role for KCa3.1 channels in human microglia, linking ATP-evoked Ca2+ transients to changes in membrane conductance, with an inflammation-dependent mechanism, and suggests that during brain inflammation the KCa3.1-mediated microglial response to purinergic signaling may be reduced.

Dataset Information

The Impact of Ca²⁺ on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

Publications

The Impact of Ca<sup>2+</sup> on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

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Dataset Information

The Impact of Ca2+ on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

Publications

The Impact of Ca<sup>2+</sup> on Intracellular Distribution of Hemoglobin in Human Erythrocytes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

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The Impact of Ca²⁺ on Intracellular Distribution of Hemoglobin in Human Erythrocytes.