title: Phosphatase and actin regulator 4 is associated with intermediate filaments in adult neural stem cells and their progenitor astrocytes.
abstract: Phosphatase and actin regulator 4 (Phactr4) is a newly discovered protein that inhibits protein phosphatase 1 and shows actin-binding activity. We previously found that Phactr4 is expressed in the neurogenic niche in adult mice, although its precise subcellular localization and possible function in neural stem cells (NSCs) is not yet understood. Here, we show that Phactr4 formed punctiform clusters in the cytosol of subventricular zone-derived adult NSCs and their progeny in vitro. These Phactr4 signals were not associated with F-actin fibers but were closely associated with intermediate filaments such as nestin and glial fibrillary acidic protein (GFAP) fibers. Direct binding of Phactr4 with nestin and GFAP filaments was demonstrated using Duolink protein interaction analyses and immunoprecipitation assays. Interestingly, when nestin fibers were de-polymerized during the mitosis or by the phosphatase inhibitor, Phactr4 appeared to be dissociated from nestin, suggesting that their protein interaction is regulated by the protein phosphorylation. These results suggest that Phactr4 forms functional associations with intermediate filament networks in adult NSCs.
authors.affiliation: Department of Anatomy, Brain Korea 21, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, 136-705, Korea.
authors.forename: Hyo Min
authors.initials: HM
authors.lastname: Cho
authors.forename: Joo Yeon
authors.initials: JY
authors.lastname: Kim
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.forename: Woong
authors.initials: W
authors.lastname: Sun
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D005904:Glial Fibrillary Acidic Protein; D007382:Intermediate Filaments / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism; D064231:Nestin / Q000378:metabolism; D058953:Neural Stem Cells / Q000166:cytology* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*
chemical_list: D003598:Cytoskeletal Proteins; D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D009687:Nuclear Proteins; C522018:Phactr4 protein, mouse; C528900:glial fibrillary astrocytic protein, mouse
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