title: De novo actin polymerization is required for model Hirano body formation in Dictyostelium.
abstract: Hirano bodies are eosinophilic, actin-rich inclusions found in autopsied brains in numerous neurodegenerative diseases. The mechanism of Hirano body formation is unknown. Mass spectrometry analysis was performed to identify proteins from partially purified model Hirano bodies from Dictyostelium This analysis identified proteins primarily belonging to ribosomes, proteasomes, mitochondria and cytoskeleton. Profilin, Arp/2/3 and WASH identified by mass spectrometry were found to colocalise with model Hirano bodies. Due to their roles in actin regulation, we selected these proteins for further investigation. Inhibition of the Arp2/3 complex by CK666 prevented formation of model Hirano bodies. Since Arp2/3 activation occurs via the WASH or WAVE complex, we next investigated how these proteins affect Hirano body formation. Whereas model Hirano bodies could form in WASH-deficient cells, they failed to form in cells lacking HSPC300, a member of the WAVE complex. We identified other proteins required for Hirano body formation that include profilin and VASP, an actin nucleation factor. In the case of VASP, both its G- and F-actin binding domains were required for model Hirano body formation. Collectively, our results indicate that de novo actin polymerization is required to form model Hirano bodies.
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, USA 30602.
authors.forename: Yun
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, USA 30602.
authors.forename: Sonbol
authors.initials: S
authors.lastname: Shahid-Salles
authors.affiliation: Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA USA 30602.
authors.forename: Dan
authors.initials: D
authors.lastname: Sherling
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, USA 30602.
authors.forename: Nathan
authors.initials: N
authors.lastname: Fechheimer
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, USA 30602.
authors.forename: Nathan
authors.initials: N
authors.lastname: Iyer
authors.affiliation: Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA USA 30602.
authors.forename: Lance
authors.initials: L
authors.lastname: Wells
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, USA 30602.
authors.forename: Marcus
authors.initials: M
authors.lastname: Fechheimer
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, USA 30602 furukawa@uga.edu.
authors.forename: Ruth
authors.identifier: http://orcid.org/0000-0002-9233-7641
authors.initials: R
authors.lastname: Furukawa
keywords: Actin binding protein; Arp2/3; Dictyostelium; HSPC300; Hirano body; Mass spectrometry; Profilin; WASH