TY - JOUR
T1 - Characterization of the megakaryocyte demarcation membrane system and its role in thrombopoiesis
AU - Schulze, Harald
AU - Korpal, Manav
AU - Hurov, Jonathan
AU - Kim, Sang We
AU - Zhang, Jinghang
AU - Cantley, Lewis C.
AU - Graf, Thomas
AU - Shivdasani, Ramesh A.
PY - 2006/5/15
Y1 - 2006/5/15
N2 - To produce blood platelets, megakaryocytes elaborate proplatelets, accompanied by expansion of membrane surface area and dramatic cytoskeletal rearrangements. The invaginated demarcation membrane system (DMS), a hallmark of mature cells, has been proposed as the source of proplatelet membranes. By direct visualization of labeled DMS, we demonstrate that this is indeed the case. Late in megakaryocyte ontogeny, the DMS gets loaded with PI-4,5-P 2, a phospholipid that is confined to plasma membranes in other cells. Appearance of PI-4,5-P2 in the DMS occurs in proximity to PI-5-P-4-kinase α (PIP4Kα), and short hairpin (sh) RNAmediated loss of PIP4Kα impairs both DMS development and expansion of megakaryocyte size. Thus, PI-4,5-P2 is a marker and possibly essential component of internal membranes. PI-4,5-P2 is known to promote actin polymerization by activating Rho-like GTPases and Wiskott-Aldrich syndrome (WASp) family proteins. Indeed, PI-4,5-P2 in the megakaryocyte DMS associates with filamentous actin. Expression of a dominant-negative N-WASp fragment or pharmacologic inhibition of actin polymerization causes similar arrests in proplatelet formation, acting at a step beyond expansion of the DMS and cell mass. These observations collectively suggest a signaling pathway wherein PI-4,5-P2 might facilitate DMS development and local assembly of actin fibers in preparation for platelet biogenesis.
AB - To produce blood platelets, megakaryocytes elaborate proplatelets, accompanied by expansion of membrane surface area and dramatic cytoskeletal rearrangements. The invaginated demarcation membrane system (DMS), a hallmark of mature cells, has been proposed as the source of proplatelet membranes. By direct visualization of labeled DMS, we demonstrate that this is indeed the case. Late in megakaryocyte ontogeny, the DMS gets loaded with PI-4,5-P 2, a phospholipid that is confined to plasma membranes in other cells. Appearance of PI-4,5-P2 in the DMS occurs in proximity to PI-5-P-4-kinase α (PIP4Kα), and short hairpin (sh) RNAmediated loss of PIP4Kα impairs both DMS development and expansion of megakaryocyte size. Thus, PI-4,5-P2 is a marker and possibly essential component of internal membranes. PI-4,5-P2 is known to promote actin polymerization by activating Rho-like GTPases and Wiskott-Aldrich syndrome (WASp) family proteins. Indeed, PI-4,5-P2 in the megakaryocyte DMS associates with filamentous actin. Expression of a dominant-negative N-WASp fragment or pharmacologic inhibition of actin polymerization causes similar arrests in proplatelet formation, acting at a step beyond expansion of the DMS and cell mass. These observations collectively suggest a signaling pathway wherein PI-4,5-P2 might facilitate DMS development and local assembly of actin fibers in preparation for platelet biogenesis.
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U2 - 10.1182/blood-2005-07-2755
DO - 10.1182/blood-2005-07-2755
M3 - Article
C2 - 16434494
AN - SCOPUS:33646540122
SN - 0006-4971
VL - 107
SP - 3868
EP - 3875
JO - Blood
JF - Blood
IS - 10
ER -