title: Proteomic investigation of the interactome of FMNL1 in hematopoietic cells unveils a role in calcium-dependent membrane plasticity.
abstract: Formin-like 1 (FMNL1) is a formin-related protein highly expressed in hematopoietic cells and overexpressed in leukemias as well as diverse transformed cell lines. It has been described to play a role in diverse functions of hematopoietic cells such as phagocytosis of macrophages as well as polarization and cytotoxicity of T cells. However, the specific role of FMNL1 in these processes has not been clarified yet and regulation by interaction partners in primary hematopoietic cells has never been investigated. We performed a proteomic screen for investigation of the interactome of FMNL1 in primary hematopoietic cells resulting in the identification of a number of interaction partners. Bioinformatic analysis considering semantic similarity suggested the giant protein AHNAK1 to be an essential interaction partner of FMNL1. We confirmed AHNAK1 as a general binding partner for FMNL1 in diverse hematopoietic cells and demonstrate that the N-terminal part of FMNL1 binds to the C-terminus of AHNAK1. Moreover, we show that the constitutively activated form of FMNL1 (FMNL1γ) induces localization of AHNAK1 to the cell membrane. Finally, we provide evidence that overexpression or knock down of FMNL1 has an impact on the capacitative calcium influx after ionomycin-mediated activation of diverse cell lines and primary cells.
authors.affiliation: Medizinische Klinik III, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Han
authors.forename: Guangchuang
authors.initials: G
authors.lastname: Yu
authors.forename: Hakan
authors.initials: H
authors.lastname: Sarioglu
authors.forename: Amélia
authors.initials: A
authors.lastname: Caballero-Martinez
authors.forename: Fabian
authors.initials: F
authors.lastname: Schlott
authors.forename: Marius
authors.initials: M
authors.lastname: Ueffing
authors.forename: Hannelore
authors.initials: H
authors.lastname: Haase
authors.forename: Christian
authors.initials: C
authors.lastname: Peschel
authors.forename: Angela M
authors.initials: AM
authors.lastname: Krackhardt
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism* / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005260:Female; D000080865:Formins; D006412:Hematopoietic Stem Cells / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D020014:K562 Cells; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D021381:Protein Transport; D040901:Proteomics; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology
chemical_list: C075176:AHNAK protein, human; D003598:Cytoskeletal Proteins; C476204:FMNL1 protein, human; D000080865:Formins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D002118:Calcium