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- Title
Beta-Glycerophosphate-Induced ORAI1 Expression and Store Operated Ca2+ Entry in Megakaryocytes.
- Authors
Pelzl, Lisann; Sahu, Itishri; Ma, Ke; Heinzmann, David; Bhuyan, Abdulla Al Mamun; al-Maghout, Tamer; Sukkar, Basma; Sharma, Yamini; Marini, Irene; Rigoni, Flaviana; Artunc, Ferruh; Cao, Hang; Gutti, Ravi; Voelkl, Jakob; Pieske, Burkert; Gawaz, Meinrad; Bakchoul, Tamam; Lang, Florian
- Abstract
Impairment of renal phosphate elimination in chronic kidney disease (CKD) leads to enhanced plasma and tissue phosphate concentration, which in turn up-regulates transcription factor NFAT5 and serum & glucocorticoid-inducible kinase SGK1. The kinase upregulates ORAI1, a Ca2+-channel accomplishing store-operated Ca2+-entry (SOCE). ORAI1 is stimulated following intracellular store depletion by Ca2+-sensors STIM1 and/or STIM2. In megakaryocytes and blood platelets SOCE and thus ORAI1 are powerful regulators of activity. The present study explored whether the phosphate-donor ß-glycerophosphate augments NFAT5, ORAI1,2,3 and/or STIM1,2 expressions and thus SOCE in megakaryocytes. Human megakaryocytic Meg01cells were exposed to 2 mM of phosphate-donor ß-glycerophosphate for 24 hours. Platelets were isolated from blood samples of patients with impaired kidney function or control volunteers. Transcript levels were estimated utilizing q-RT-PCR, cytosolic Ca2+-concentration ([Ca2+]i) by Fura-2-fluorescence, and SOCE from increase of [Ca2+]i following re-addition of extracellular Ca2+ after store depletion with thapsigargin (1 µM). NFAT5 and ORAI1 protein abundance was estimated with Western blots. As a result, ß-glycerophosphate increased NFAT5, ORAI1/2/3, STIM1/2 transcript levels, as well as SOCE. Transcript levels of NFAT5, SGK1, ORAI1/2/3, and STIM1/2 as well as NFAT5 and ORAI1 protein abundance were significantly higher in platelets isolated from patients with impaired kidney function than in platelets from control volunteers. In conclusion, phosphate-donor ß-glycerophosphate triggers a signaling cascade of NFAT5/SGK1/ORAI/STIM, thus up-regulating store-operated Ca2+-entry.
- Subjects
CALCIUM ions; MEGAKARYOCYTES; BLOOD platelets; WESTERN immunoblotting; BLOOD testing
- Publication
Scientific Reports, 2020, Vol 10, Issue 1, p1
- ISSN
2045-2322
- Publication type
Article
- DOI
10.1038/s41598-020-58384-x