Role of the clathrin adaptor PICALM in normal hematopoiesis and polycythemia vera pathophysiology
Yuichi Ishikawa,
Manami Maeda,
Mithun Pasham,
Francois Aguet,
Silvia K. Tacheva-Grigorova,
Takeshi Masuda,
Hai Yi,
Sung-Uk Lee,
Jian Xu,
Julie Teruya-Feldstein,
Maria Ericsson,
Ann Mullally,
John Heuser,
Tom Kirchhausen,
Takahiro Maeda
Affiliations
Yuichi Ishikawa
Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of the City of Hope, Duarte, CA, USA;Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA;Department of Hematology and Oncology, Nagoya University Graduate School of Medicine, Japan
Manami Maeda
Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of the City of Hope, Duarte, CA, USA;Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Mithun Pasham
Department of Cell Biology, Harvard Medical School, Boston, MA, USA;Department of Pediatrics Harvard Medical School, Boston, MA, USA;Program in Cellular & Molecular Medicine, Boston Children’s Hospital, MA, USA
Francois Aguet
Department of Cell Biology, Harvard Medical School, Boston, MA, USA
Silvia K. Tacheva-Grigorova
Department of Cell Biology, Harvard Medical School, Boston, MA, USA;Department of Pediatrics Harvard Medical School, Boston, MA, USA;Program in Cellular & Molecular Medicine, Boston Children’s Hospital, MA, USA
Takeshi Masuda
Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Hai Yi
Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA;Department of Hematology, General Hospital of Chengdu Military Region, Chengdu, China
Sung-Uk Lee
Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of the City of Hope, Duarte, CA, USA;Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Jian Xu
Children’s Research Institute, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
Julie Teruya-Feldstein
Department of Pathology, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Maria Ericsson
Department of Cell Biology, Harvard Medical School, Boston, MA, USA
Ann Mullally
Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
John Heuser
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
Tom Kirchhausen
Department of Cell Biology, Harvard Medical School, Boston, MA, USA;Department of Pediatrics Harvard Medical School, Boston, MA, USA;Program in Cellular & Molecular Medicine, Boston Children’s Hospital, MA, USA
Takahiro Maeda
Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of the City of Hope, Duarte, CA, USA;Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Clathrin-dependent endocytosis is an essential cellular process shared by all cell types. Despite this, precisely how endocytosis is regulated in a cell-type-specific manner and how this key pathway functions physiologically or pathophysiologically remain largely unknown. PICALM, which encodes the clathrin adaptor protein PICALM, was originally identified as a component of the CALM/AF10 leukemia oncogene. Here we show, by employing a series of conditional Picalm knockout mice, that PICALM critically regulates transferrin uptake in erythroid cells by functioning as a cell-type-specific regulator of transferrin receptor endocytosis. While transferrin receptor is essential for the development of all hematopoietic lineages, Picalm was dispensable for myeloid and B-lymphoid development. Furthermore, global Picalm inactivation in adult mice did not cause gross defects in mouse fitness, except for anemia and a coat color change. Freeze-etch electron microscopy of primary erythroblasts and live-cell imaging of murine embryonic fibroblasts revealed that Picalm function is required for efficient clathrin coat maturation. We showed that the PICALM PIP2 binding domain is necessary for transferrin receptor endocytosis in erythroblasts and absolutely essential for erythroid development from mouse hematopoietic stem/progenitor cells in an erythroid culture system. We further showed that Picalm deletion entirely abrogated the disease phenotype in a Jak2V617F knock-in murine model of polycythemia vera. Our findings provide new insights into the regulation of cell-type-specific transferrin receptor endocytosis in vivo. They also suggest a new strategy to block cellular uptake of transferrin-bound iron, with therapeutic potential for disorders characterized by inappropriate red blood cell production, such as polycythemia vera.
