Enhanced Expression of Stim, Orai, and TRPC Transcripts and Proteins in Endothelial Progenitor Cells Isolated from Patients with Primary Myelofibrosis

• Published in: PloS one Vol. 9; no. 3; p. e91099
• Main Authors: Dragoni, Silvia, Laforenza, Umberto, Bonetti, Elisa, Reforgiato, Marta, Poletto, Valentina, Lodola, Francesco, Bottino, Cinzia, Guido, Daniele, Rappa, Alessandra, Pareek, Sumedha, Tomasello, Mario, Guarrera, Maria Rosa, Cinelli, Maria Pia, Aronica, Adele, Guerra, Germano, Barosi, Giovanni, Tanzi, Franco, Rosti, Vittorio, Moccia, Francesco
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06.03.2014; Public Library of Science (PLoS)
• Subjects: Adenosine Triphosphate - pharmacology; Adult; Aged; Anilides - pharmacology; ATP; Biology; Bone marrow; Calcium - metabolism; Calcium channels; Calcium Channels - genetics; Calcium Channels - metabolism; Calcium imaging; Calcium influx; Cell Proliferation - drug effects; Cell Separation; Cells (biology); Colony-Forming Units Assay; Cyclopiazonic acid; Depletion; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum - metabolism; Endothelial Progenitor Cells - drug effects; Endothelial Progenitor Cells - metabolism; Endothelium; Female; Fibrosis; Gadolinium; Gadolinium - pharmacology; Humans; Immunoblotting; Indoles - pharmacology; Inositol; Inositol 1,4,5-Trisphosphate - metabolism; Inositol 1,4,5-trisphosphate receptors; Intracellular Space - drug effects; Intracellular Space - metabolism; Lanthanum - pharmacology; Male; Medicine; Membrane Potentials - drug effects; Membrane Proteins - genetics; Membrane Proteins - metabolism; Middle Aged; Molecular structure; Myelofibrosis; Neovascularization; Orai1 protein; Overexpression; Patients; Pharmacology; Phospholipase; Phospholipase C; Physiological aspects; Polymerase chain reaction; Primary Myelofibrosis - genetics; Primary Myelofibrosis - pathology; Progenitor cells; Proteins; Renal cell carcinoma; RNA, Messenger - genetics; RNA, Messenger - metabolism; Signal transduction; Signal Transduction - drug effects; Signaling; Spleen; Stem cells; STIM1 protein; Thiadiazoles - pharmacology; Transient receptor potential proteins; TRPC Cation Channels - genetics; TRPC Cation Channels - metabolism; Young Adult
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0091099

An increase in the frequency of circulating endothelial colony forming cells (ECFCs), the only subset of endothelial progenitor cells (EPCs) truly belonging to the endothelial phenotype, occurs in patients affected by primary myelofibrosis (PMF). Herein, they might contribute to the enhanced neovascularisation of fibrotic bone marrow and spleen. Store-operated Ca2+ entry (SOCE) activated by the depletion of the inositol-1,4,5-trisphosphate (InsP3)-sensitive Ca2+ store drives proliferation in ECFCs isolated from both healthy donors (N-ECFCs) and subjects suffering from renal cellular carcinoma (RCC-ECFCs). SOCE is up-regulated in RCC-ECFCs due to the over-expression of its underlying molecular components, namely Stim1, Orai1, and TRPC1. We utilized Ca2+ imaging, real-time polymerase chain reaction, western blot analysis and functional assays to evaluate molecular structure and the functional role of SOCE in ECFCs derived from PMF patients (PMF-ECFCs). SOCE, induced by either pharmacological (i.e. cyclopiazonic acid or CPA) or physiological (i.e. ATP) stimulation, was significantly higher in PMF-ECFCs. ATP-induced SOCE was inhibited upon blockade of the phospholipase C/InsP3 signalling pathway with U73111 and 2-APB. The higher amplitude of SOCE was associated to the over-expression of the transcripts encoding for Stim2, Orai2-3, and TRPC1. Conversely, immunoblotting revealed that Stim2 levels remained constant as compared to N-ECFCs, while Stim1, Orai1, Orai3, TRPC1 and TRPC4 proteins were over-expressed in PMF-ECFCs. ATP-induced SOCE was inhibited by BTP-2 and low micromolar La3+ and Gd3+, while CPA-elicited SOCE was insensitive to Gd3+. Finally, BTP-2 and La3+ weakly blocked PMF-ECFC proliferation, while Gd3+ was ineffective. Two distinct signalling pathways mediate SOCE in PMF-ECFCs; one is activated by passive store depletion and is Gd3+-resistant, while the other one is regulated by the InsP3-sensitive Ca2+ pool and is inhibited by Gd3+. Unlike N- and RCC-ECFCs, the InsP3-dependent SOCE does not drive PMF-ECFC proliferation.