Beta-Glycerophosphate-Induced ORAI1 Expression and Store Operated Ca2+ Entry in Megakaryocytes

Sci Rep. 2020 Feb 3;10(1):1728. doi: 10.1038/s41598-020-58384-x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Blood Platelets / physiology*
  • Calcium / metabolism
  • Cells, Cultured
  • Female
  • Glycerophosphates / metabolism*
  • Humans
  • Immediate-Early Proteins / genetics
  • Immediate-Early Proteins / metabolism*
  • Kidney / metabolism*
  • Kidney / pathology
  • Male
  • Megakaryocytes / physiology*
  • Middle Aged
  • NFATC Transcription Factors / metabolism
  • ORAI1 Protein / genetics
  • ORAI1 Protein / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Renal Insufficiency, Chronic / metabolism*
  • Signal Transduction
  • Stromal Interaction Molecule 1 / metabolism
  • Stromal Interaction Molecule 2 / metabolism
  • Up-Regulation


  • Glycerophosphates
  • Immediate-Early Proteins
  • NFATC Transcription Factors
  • ORAI1 Protein
  • ORAI1 protein, human
  • Stromal Interaction Molecule 1
  • Stromal Interaction Molecule 2
  • Protein Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase
  • Calcium
  • beta-glycerophosphoric acid