title: RhoA-mediated apical actin enrichment is required for ciliogenesis and promoted by Foxj1.
abstract: Programs that direct cellular differentiation are dependent on the strict temporal expression of regulatory factors that can be provided by Rho GTPases. Ciliogenesis is a complex sequence of events involving the generation and docking of basal bodies at the apical membrane, followed by ciliary axoneme generation. Although a cilia proteome has been assembled, programs that direct ciliated cell differentiation are not well established, particularly in mammalian systems. Using mouse primary culture airway epithelial cells, we identified a critical stage of ciliogenesis requiring the temporal establishment of an apical web-like structure of actin for basal body docking and subsequent axoneme growth. Apical web formation and basal body docking were prevented by interruption of actin remodeling and were dependent on RhoA activation. Additional evidence for this program was provided by analysis of Foxj1-null mice that failed to dock basal bodies and lacked apical actin. Foxj1 expression coincided with actin web formation, activated RhoA and RhoB, and persisted despite RhoA inhibition, suggesting that Foxj1 promoted RhoA during ciliogenesis. Apical ezrin localization was also dependent on Foxj1, actin remodeling, and RhoA, but was not critical for ciliogenesis. Thus, temporal Foxj1 and RhoA activity are essential regulatory events for cytoskeletal remodeling during mammalian ciliogenesis.
authors.affiliation: Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: Jiehong
authors.initials: J
authors.lastname: Pan
authors.forename: Yingjian
authors.initials: Y
authors.lastname: You
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.forename: Steven L
authors.initials: SL
authors.lastname: Brody
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects; D002923:Cilia / Q000187:drug effects / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D005098:Exotoxins / Q000494:pharmacology; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006801:Humans; D051379:Mice; D041681:NIH 3T3 Cells; D021381:Protein Transport / Q000187:drug effects; D012137:Respiratory System / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000099149:Ezrin
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D005098:Exotoxins; D051858:Forkhead Transcription Factors; D020742:rhoA GTP-Binding Protein; D000099149:Ezrin; C481963:FOXJ1 protein, mouse