Abstract
Calreticulin (CALR) is a multifunctional molecular chaperone that regulates Ca2+ homeostasis and protein folding in the endoplasmic reticulum (ER). Mutations in exon 9 of Calr are the second most common genetic cause of myeloproliferative neoplasms (MPNs), incurring a characteristic increase of megakaryocytes (platelet precursors) in the bone marrow.
Several studies demonstrate that CALR mutated megakaryocyte proliferation involves a cytokine-independent constitutive activation of the Janus Kinase (JAK)-signal transducer and activator of transcription (STAT) signalling due to the binding of mutant CALR to the thrombopoietin receptor. However, the impact of Ca2+ alterations in CALR mutations is unclear. To examine this, we employed a dual-guide CRISPR/Cas9 approach to generate the common type I CALR mutations (52-bp deletion) in human myelogenous K-562 cells.