title: A meckelin-filamin A interaction mediates ciliogenesis.
abstract: MKS3, encoding the transmembrane receptor meckelin, is mutated in Meckel-Gruber syndrome (MKS), an autosomal-recessive ciliopathy. Meckelin localizes to the primary cilium, basal body and elsewhere within the cell. Here, we found that the cytoplasmic domain of meckelin directly interacts with the actin-binding protein filamin A, potentially at the apical cell surface associated with the basal body. Mutations in FLNA, the gene for filamin A, cause periventricular heterotopias. We identified a single consanguineous patient with an MKS-like ciliopathy that presented with both MKS and cerebellar heterotopia, caused by an unusual in-frame deletion mutation in the meckelin C-terminus at the region of interaction with filamin A. We modelled this mutation and found it to abrogate the meckelin-filamin A interaction. Furthermore, we found that loss of filamin A by siRNA knockdown, in patient cells, and in tissues from Flna(Dilp2) null mouse embryos results in cellular phenotypes identical to those caused by meckelin loss, namely basal body positioning and ciliogenesis defects. In addition, morpholino knockdown of flna in zebrafish embryos significantly increases the frequency of dysmorphology and severity of ciliopathy developmental defects caused by mks3 knockdown. Our results suggest that meckelin forms a functional complex with filamin A that is disrupted in MKS and causes defects in neuronal migration and Wnt signalling. Furthermore, filamin A has a crucial role in the normal processes of ciliogenesis and basal body positioning. Concurrent with these processes, the meckelin-filamin A signalling axis may be a key regulator in maintaining correct, normal levels of Wnt signalling.
authors: Ciliopathy Research Group, Section of Ophthalmology and Neurosciences, Leeds Institute of Molecular Medicine, University of Leeds, Leeds LS9 7TF, UK.
authors: Matthew
authors: M
authors: Adams
authors: Roslyn J
authors: RJ
authors: Simms
authors: Zakia
authors: Z
authors: Abdelhamed
authors: Helen R
authors: HR
authors: Dawe
authors: Katarzyna
authors: K
authors: Szymanska
authors: Clare V
authors: CV
authors: Logan
authors: Gabrielle
authors: G
authors: Wheway
authors: Eva
authors: E
authors: Pitt
authors: Keith
authors: K
authors: Gull
authors: Margaret A
authors: MA
authors: Knowles
authors: Edward
authors: E
authors: Blair
authors: Sally H
authors: SH
authors: Cross
authors: John A
authors: JA
authors: Sayer
authors: Colin A
authors: CA
authors: Johnson
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002925:Ciliary Motility Disorders / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D003285:Contractile Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D064448:Filamins; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D034741:RNA, Small Interfering / Q000235:genetics; D020798:Two-Hybrid System Techniques; D015027:Zebrafish / Q000196:embryology
chemical_list: D003285:Contractile Proteins; D064448:Filamins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D034741:RNA, Small Interfering; C468846:TMEM67 protein, human