Disruption of the basal body compromises proteasomal function and perturbs intracellular Wnt response.
Primary cilia and basal bodies are evolutionarily conserved organelles that mediate communication between the intracellular and extracellular environments. Here we show that bbs1, bbs4 and mkks (also known as bbs6), which encode basal body proteins, are required for convergence and extension in zebrafish and interact with wnt11 and wnt5b. Suppression of bbs1, bbs4 and mkks transcripts results in stabilization of beta-catenin with concomitant upregulation of T-cell factor (TCF)-dependent transcription in both zebrafish embryos and mammalian ciliated cells, a defect phenocopied by the silencing of the axonemal kinesin subunit KIF3A but not by chemical disruption of the cytoplasmic microtubule network. These observations are attributable partly to defective degradation by the proteasome; suppression of BBS4 leads to perturbed proteasomal targeting and concomitant accumulation of cytoplasmic beta-catenin. Cumulatively, our data indicate that the basal body is an important regulator of Wnt signal interpretation through selective proteolysis and suggest that defects in this system may contribute to phenotypes pathognomonic of human ciliopathies.
Gerdes
Jantje M
JM
McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Liu
Yangfan
Y
Zaghloul
Norann A
NA
Leitch
Carmen C
CC
Lawson
Shaneka S
SS
Kato
Masaki
M
Beachy
Philip A
PA
Beales
Philip L
PL
DeMartino
George N
GN
Fisher
Shannon
S
Badano
Jose L
JL
Katsanis
Nicholas
N
D000818:Animals; D002478:Cells, Cultured; D002924:Ciliary Body / Q000378:metabolism*; D003593:Cytoplasm; D003599:Cytoskeleton / Q000737:chemistry / Q000648:ultrastructure; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D056385:Group II Chaperonins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008845:Microinjections; D008870:Microtubules / Q000378:metabolism*; D010641:Phenotype; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D051820:TCF Transcription Factors; D014158:Transcription, Genetic; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
C506279:Mkks protein, mouse; D061988:Proteasome Inhibitors; D051820:TCF Transcription Factors; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin; D008156:Luciferases; D046988:Proteasome Endopeptidase Complex; D056385:Group II Chaperonins; D016547:Kinesins