title: Immature human megakaryocytes produce nuclear-associated acetylcholinesterase.
abstract: Acetylcholinesterase (AChE) is expressed in murine megakaryocytes (MK), where its antisense inhibition suppresses differentiation, yet was never detected in human MK. Here, we report that AChE is produced in normal human bone marrow MK and in cell lines derived thereof. Reverse transcriptase-polymerase chain reaction (RT-PCR) amplification showed two ACHEmRNA forms in human megakaryoblastic DAMI cells. In situ hybridization demonstrated ACHEmRNA surrounding the nucleus of small DAMI cells and the nuclear lobes of large, polyploid cells. Differentiation induction with phorbol ester and exposure to recombinant human thrombopoietin suppressed both ACHEmRNA and AChE activity. The residual AChE in mature differentiated cells acquired higher stability and detergent-sensitivity as compared with AChE in small proliferating cells. AChE activity was primarily associated with nuclei of both DAMI cells and small (10 microm) primary proliferating human bone marrow MK identified with GPIIb/IIIa antibodies. This activity was significantly reduced in medium size MK (10 to 25 microm) and was almost undetectable in large MK (>25 microm), yet was twofold more abundant in some large MK from idiopathic thrombocytopenia purpura (ITP) patients with accelerated MK maturation. The loss of AChE activity at the transition from proliferating to differentiating MK highlights species-specific differences in its expression, suggesting a distinct role for AChE in human MK development.
authors.affiliation: Department of Biological Chemistry, The Life Sciences Institute, the Hebrew University of Jerusalem, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Lev-Lehman
authors.forename: V
authors.initials: V
authors.lastname: Deutsch
authors.forename: A
authors.initials: A
authors.lastname: Eldor
authors.forename: H
authors.initials: H
authors.lastname: Soreq
mesh_terms: D000110:Acetylcholinesterase / Q000096:biosynthesis*; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000201:enzymology*; D002478:Cells, Cultured; D004790:Enzyme Induction; D006801:Humans; D008533:Megakaryocytes / Q000201:enzymology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D013045:Species Specificity; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013926:Thrombopoietin / Q000494:pharmacology
chemical_list: D012333:RNA, Messenger; D011994:Recombinant Proteins; D013926:Thrombopoietin; D000110:Acetylcholinesterase; D013755:Tetradecanoylphorbol Acetate