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The Calreticulin control of human stress erythropoiesis is impaired by JAK2V617F in polycythemia vera
- Source :
- Experimental Hematology. 50:53-76
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- Calreticulin (CALR) is a Ca2+-binding protein that shuttles among cellular compartments with proteins bound to its N/P domains. The knowledge that activation of the human erythropoietin receptor induces Ca2+ fluxes prompted us to investigate the role of CALR in human erythropoiesis. As shown by Western blot analysis, erythroblasts generated in vitro from normal sources and JAK2V617F polycythemia vera (PV) patients expressed robust levels of CALR. However, Ca2+ regulated CALR conformation only in normal cells. Normal erythroblasts expressed mostly the N-terminal domain of CALR (N-CALR) on their cell surface (as shown by flow cytometry) and C-terminal domain (C-CALR) in their cytoplasm (as shown by confocal microscopy) and expression of both epitopes decreased with maturation. In the proerythroblast (proEry) cytoplasm, C-CALR was associated with the glucocorticoid receptor (GR), which initiated the stress response. In these cells, Ca2+ deprivation and inhibition of nuclear export increased GR nuclear localization while decreasing cytoplasmic detection of C-CALR and C-CALR/GR association and proliferation in response to the GR agonist dexamethasone (Dex). C-CALR/GR association and Dex responsiveness were instead increased by Ca2+ and erythropoietin. In contrast, JAK2V617F proErys expressed normal cell-surface levels of N-CALR but barely detectable cytoplasmic levels of C-CALR. These cells contained GR mainly in the nucleus and were Dex unresponsive. Ruxolitinib rescued cytoplasmic detection of C-CALR, C-CALR/GR association, and Dex responsiveness in JAK2V617F proErys and its effects were antagonized by nuclear export and Ca2+ flux inhibitors. These results indicates that Ca2+-induced conformational changes of CALR regulate nuclear export of GR in normal erythroblasts and that JAK2V617F deregulates this function in PV.
- Subjects :
- 0301 basic medicine
Cancer Research
medicine.medical_specialty
Erythroblasts
Article
Cell Line
Immunophenotyping
Flow cytometry
03 medical and health sciences
intracellular-free calcium
Receptors, Glucocorticoid
Glucocorticoid receptor
Erythroid Cells
Calreticulin erythropoiesis JAK2V617F polycythemia
glucocorticoid-receptor-beta
Internal medicine
Genetics
medicine
Humans
Erythropoiesis
Codon
Nuclear export signal
Polycythemia Vera
Molecular Biology
medicine.diagnostic_test
biology
in vitro
Cell Differentiation
Cell Biology
Hematology
Janus Kinase 2
Molecular biology
Erythropoietin receptor
Protein Transport
030104 developmental biology
Endocrinology
Amino Acid Substitution
Cytoplasm
Erythropoietin
Mutation
biology.protein
Calcium
Calreticulin
Signal Transduction
medicine.drug
Subjects
Details
- ISSN :
- 0301472X
- Volume :
- 50
- Database :
- OpenAIRE
- Journal :
- Experimental Hematology
- Accession number :
- edsair.doi.dedup.....249d5d000b6e1a35b7510515a871e9e3