title: Biogenesis of the demarcation membrane system (DMS) in megakaryocytes.
abstract: The demarcation membrane system (DMS) in megakaryocytes forms the plasma membrane (PM) of future platelets. Using confocal microscopy, electron tomography, and large volume focused ion beam/scanning electron microscopy (FIB/SEM), we determined the sequential steps of DMS formation. We identified a pre-DMS that initiated at the cell periphery and was precisely located between the nuclear lobes. At all developmental stages, the DMS remained continuous with the cell surface. The number of these connections correlated well with the nuclear lobulation, suggesting a relationship with cleavage furrow formation and abortive cytokinesis. On DMS expansion, Golgi complexes assembled around the pre-DMS, and fusion profiles between trans-golgi network-derived vesicles and the DMS were observed. Brefeldin-A reduced DMS expansion, indicating that the exocytic pathway is essential for DMS biogenesis. Close contacts between the endoplasmic reticulum (ER) and the DMS were detected, suggesting physical interaction between the 2 membrane systems. FIB/SEM revealed that the DMS forms an intertwined tubular membrane network resembling the platelet open canalicular system. We thus propose the following steps in DMS biogenesis: (1) focal membrane assembly at the cell periphery; (2) PM invagination and formation of a perinuclear pre-DMS; (3) expansion through membrane delivery from Golgi complexes; and (4) ER-mediated lipid transfer.
authors.affiliation: Unité mixte de recherche S949 Institut National de la Santé et de la Recherche Médicale, Université de Strasbourg, Etablissement Français du Sang-Alsace, Strasbourg, France;
authors.forename: Anita
authors.initials: A
authors.lastname: Eckly
authors.forename: Harry
authors.initials: H
authors.lastname: Heijnen
authors.forename: Fabien
authors.initials: F
authors.lastname: Pertuy
authors.forename: Willie
authors.initials: W
authors.lastname: Geerts
authors.forename: Fabienne
authors.initials: F
authors.lastname: Proamer
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Rinckel
authors.forename: Catherine
authors.initials: C
authors.lastname: Léon
authors.forename: François
authors.initials: F
authors.lastname: Lanza
authors.forename: Christian
authors.initials: C
authors.lastname: Gachet
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008533:Megakaryocytes / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism*