title: Dynamin Binding Protein (Tuba) Deficiency Inhibits Ciliogenesis and Nephrogenesis in Vitro and in Vivo.
abstract: Dysfunction of renal primary cilia leads to polycystic kidney disease. We previously showed that the exocyst, a protein trafficking complex, is essential for ciliogenesis and regulated by multiple Rho and Rab family GTPases, such as Cdc42. Cdc42 deficiency resulted in a disruption of renal ciliogenesis and a polycystic kidney disease phenotype in zebrafish and mice. Here we investigate the role of Dynamin binding protein (also known as Tuba), a Cdc42-specific guanine nucleotide exchange factor, in ciliogenesis and nephrogenesis using Tuba knockdown Madin-Darby canine kidney cells and tuba knockdown in zebrafish. Tuba depletion resulted in an absence of cilia, with impaired apical polarization and inhibition of hepatocyte growth factor-induced tubulogenesis in Tuba knockdown Madin-Darby canine kidney cell cysts cultured in a collagen gel. In zebrafish, tuba was expressed in multiple ciliated organs, and, accordingly, tuba start and splice site morphants showed various ciliary mutant phenotypes in these organs. Co-injection of tuba and cdc42 morpholinos at low doses, which alone had no effect, resulted in genetic synergy and led to abnormal kidney development with highly disorganized pronephric duct cilia. Morpholinos targeting two other guanine nucleotide exchange factors not known to be in the Cdc42/ciliogenesis pathway and a scrambled control morpholino showed no phenotypic effect. Given the molecular nature of Cdc42 and Tuba, our data strongly suggest that tuba and cdc42 act in the same ciliogenesis pathway. Our study demonstrates that Tuba deficiency causes an abnormal renal ciliary and morphogenetic phenotype. Tuba most likely plays a critical role in ciliogenesis and nephrogenesis by regulating Cdc42 activity.
authors.affiliation: From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and.
authors.forename: Jeong-In
authors.initials: JI
authors.lastname: Baek
authors.affiliation: From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and.
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Kwon
authors.affiliation: From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zuo
authors.affiliation: From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Choi
authors.affiliation: From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and.
authors.forename: Seok-Hyung
authors.initials: SH
authors.lastname: Kim
authors.affiliation: From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425 and the Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401 Lipschut@musc.edu.
authors.forename: Joshua H
authors.initials: JH
authors.lastname: Lipschutz
mesh_terms: D000818:Animals; D002923:Cilia / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D055785:Gene Knockdown Techniques; D007668:Kidney / Q000196:embryology*; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D038081:Organogenesis / Q000502:physiology*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D003598:Cytoskeletal Proteins; D029961:Zebrafish Proteins; D020764:cdc42 GTP-Binding Protein
keywords: CDC42; cilia; guanine nucleotide exchange factor (GEF); kidney; membrane trafficking