title: Disease causing mutations in inverted formin 2 regulate its binding to G-actin, F-actin capping protein (CapZ α-1) and profilin 2.
abstract: Focal segmental glomerulosclerosis (FSGS) is a devastating form of nephrotic syndrome which ultimately leads to end stage renal failure (ESRF). Mutations in inverted formin 2 (INF2), a member of the formin family of actin-regulating proteins, have recently been associated with a familial cause of nephrotic syndrome characterized by FSGS. INF2 is a unique formin that can both polymerize and depolymerize actin filaments. How mutations in INF2 lead to disease is unknown. In the present study, we show that three mutations associated with FSGS, E184K, S186P and R218Q, reduce INF2 auto-inhibition and increase association with monomeric actin. Furthermore using a combination of GFP-INF2 expression in human podocytes and GFP-Trap purification coupled with MS we demonstrate that INF2 interacts with profilin 2 and the F-actin capping protein, CapZ α-1. These interactions are increased by the presence of the disease causing mutations. Since both these proteins are involved in the dynamic turnover and restructuring of the actin cytoskeleton these changes strengthen the evidence that aberrant regulation of actin dynamics underlies the pathogenesis of disease.
authors.affiliation: Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, U.K.
authors.forename: Ruth
authors.initials: R
authors.lastname: Rollason
authors.affiliation: Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, U.K.
authors.forename: Matthew
authors.initials: M
authors.lastname: Wherlock
authors.affiliation: Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, U.K.
authors.forename: Jenny A
authors.initials: JA
authors.lastname: Heath
authors.affiliation: Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, U.K.
authors.forename: Kate J
authors.initials: KJ
authors.lastname: Heesom
authors.affiliation: Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, U.K.
authors.forename: Moin A
authors.initials: MA
authors.lastname: Saleem
authors.affiliation: Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, U.K. g.i.welsh@bristol.ac.uk.
authors.forename: Gavin I
authors.initials: GI
authors.lastname: Welsh
mesh_terms: D019943:Amino Acid Substitution; D051347:CapZ Actin Capping Protein / Q000235:genetics / Q000378:metabolism; D000080865:Formins; D005923:Glomerulosclerosis, Focal Segmental / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D051304:Profilins / Q000235:genetics / Q000378:metabolism
chemical_list: C495842:CAPZA1 protein, human; D051347:CapZ Actin Capping Protein; C587953:Fmn2 protein, human; D000080865:Formins; D008840:Microfilament Proteins; D009687:Nuclear Proteins; C495741:PFN2 protein, human; D051304:Profilins
keywords: FSGS; actin cytoskeleton; podocytes; proteomics