title: An incomplete trafficking defect to the cell-surface leads to paradoxical thrombocytosis for human and murine MPL P106L.
abstract: The mechanisms behind the hereditary thrombocytosis induced by the thrombopoietin (THPO) receptor MPL P106L mutant remain unknown. A complete trafficking defect to the cell surface has been reported, suggesting either weak constitutive activity or nonconventional THPO-dependent mechanisms. Here, we report that the thrombocytosis phenotype induced by MPL P106L belongs to the paradoxical group, where low MPL levels on platelets and mature megakaryocytes (MKs) lead to high serum THPO levels, whereas weak but not absent MPL cell-surface localization in earlier MK progenitors allows response to THPO by signaling and amplification of the platelet lineage. MK progenitors from patients showed no spontaneous growth and responded to THPO, and MKs expressed MPL on their cell surface at low levels, whereas their platelets did not respond to THPO. Transduction of MPL P106L in CD34+cells showed that this receptor was more efficiently localized at the cell surface on immature than on mature MKs, explaining a proliferative response to THPO of immature cells and a defect in THPO clearance in mature cells. In a retroviral mouse model performed in Mpl-/-mice, MPL P106L could induce a thrombocytosis phenotype with high circulating THPO levels. Furthermore, we could select THPO-dependent cell lines with more cell-surface MPL P106L localization that was detected by flow cytometry and [125I]-THPO binding. Altogether, these results demonstrate that MPL P106L is a receptor with an incomplete defect in trafficking, which induces a low but not absent localization of the receptor on cell surface and a response to THPO in immature MK cells.
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.|Assistance Publique-Hôpitaux de Paris, Laboratoire d'Hématologie Hôpital Saint-Antoine, Paris, France.
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Favale
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: Kahia
authors.initials: K
authors.lastname: Messaoudi
authors.affiliation: de Duve Institute, Université catholique de Louvain, Brussels, Belgium.|Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium; and.
authors.forename: Leila N
authors.initials: LN
authors.lastname: Varghese
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: Siham
authors.initials: S
authors.lastname: Boukour
authors.affiliation: de Duve Institute, Université catholique de Louvain, Brussels, Belgium.|Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium; and.
authors.forename: Christian
authors.initials: C
authors.lastname: Pecquet
authors.affiliation: de Duve Institute, Université catholique de Louvain, Brussels, Belgium.|Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium; and.
authors.forename: Vitalina
authors.initials: V
authors.lastname: Gryshkova
authors.affiliation: de Duve Institute, Université catholique de Louvain, Brussels, Belgium.|Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium; and.
authors.forename: Jean Philippe
authors.initials: JP
authors.lastname: Defour
authors.affiliation: de Duve Institute, Université catholique de Louvain, Brussels, Belgium.|Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium; and.
authors.forename: Roxana-Irina
authors.initials: RI
authors.lastname: Albu
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bluteau
authors.affiliation: Assistance Publique-Hôpitaux de Paris, Laboratoire d'Hématologie, Hôpital Trousseau, Paris, France.
authors.forename: Paola
authors.initials: P
authors.lastname: Ballerini
authors.affiliation: Assistance Publique-Hôpitaux de Paris, Laboratoire d'Hématologie, Hôpital Trousseau, Paris, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Leverger
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Plo
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: Najet
authors.initials: N
authors.lastname: Debili
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: Hana
authors.initials: H
authors.lastname: Raslova
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.|Assistance Publique-Hôpitaux de Paris, Laboratoire d'Hématologie, Hôpital Trousseau, Paris, France.
authors.forename: Remi
authors.initials: R
authors.lastname: Favier
authors.affiliation: de Duve Institute, Université catholique de Louvain, Brussels, Belgium.|Ludwig Institute for Cancer Research, Brussels Branch, Brussels, Belgium; and.
authors.forename: Stefan N
authors.initials: SN
authors.lastname: Constantinescu
authors.affiliation: INSERM, UMR 1170, Équipe labellisée Ligue Nationale contre le Cancer, Gustave Roussy, Villejuif, France.|Université Paris-Saclay, UMR 1170 Équipe labellisée par le GrEx, Gustave Roussy, Villejuif, France.|Gustave Roussy, UMR 1170, Villejuif, France.
authors.forename: William
authors.initials: W
authors.lastname: Vainchenker
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004195:Disease Models, Animal; D059865:Endoplasmic Reticulum Stress; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D008533:Megakaryocytes / Q000378:metabolism; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D021381:Protein Transport; D053628:Receptors, Thrombopoietin / Q000235:genetics* / Q000378:metabolism; D012190:Retroviridae / Q000378:metabolism; D013922:Thrombocytosis / Q000235:genetics* / Q000473:pathology*; D014161:Transduction, Genetic
chemical_list: C481270:Mpl protein, mouse; D053628:Receptors, Thrombopoietin; C082218:MPL protein, human