title: Septins 2, 7 and 9 and MAP4 colocalize along the axoneme in the primary cilium and control ciliary length.
abstract: Septins are a large, evolutionarily conserved family of GTPases that form hetero-oligomers and interact with the actin-based cytoskeleton and microtubules. They are involved in scaffolding functions, and form diffusion barriers in budding yeast, the sperm flagellum and the base of primary cilia of kidney epithelial cells. We investigated the role of septins in the primary cilium of retinal pigmented epithelial (RPE) cells, and found that SEPT2 forms a 1:1:1 complex with SEPT7 and SEPT9 and that the three members of this complex colocalize along the length of the axoneme. Similar to observations in kidney epithelial cells, depletion of cilium-localized septins by siRNA-based approaches inhibited ciliogenesis. MAP4, which is a binding partner of SEPT2 and controls the accessibility of septins to microtubules, was also localized to the axoneme where it appeared to negatively regulate ciliary length. Taken together, our data provide new insights into the functions and regulation of septins and MAP4 in the organization of the primary cilium and microtubule-based activities in cells.
authors.affiliation: INSERM U1016, Insitut Cochin, Paris, France.
authors.forename: Rania
authors.initials: R
authors.lastname: Ghossoub
authors.forename: Qicong
authors.initials: Q
authors.lastname: Hu
authors.forename: Marion
authors.initials: M
authors.lastname: Failler
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Rouyez
authors.forename: Benjamin
authors.initials: B
authors.lastname: Spitzbarth
authors.forename: Serge
authors.initials: S
authors.lastname: Mostowy
authors.forename: Uwe
authors.initials: U
authors.lastname: Wolfrum
authors.forename: Sophie
authors.initials: S
authors.lastname: Saunier
authors.forename: Pascale
authors.initials: P
authors.lastname: Cossart
authors.forename: W
authors.initials: W
authors.lastname: Jamesnelson
authors.forename: Alexandre
authors.initials: A
authors.lastname: Benmerah
mesh_terms: D000199:Actins / Q000378:metabolism; D054468:Axoneme / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D002923:Cilia / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D012160:Retina / Q000378:metabolism / Q000502:physiology; D058112:Septins / Q000378:metabolism*
chemical_list: D000199:Actins; D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; C000602252:SEPTIN2 protein, human; C113158:SEPTIN7 protein, human; C474315:SEPTIN9 protein, human; D058112:Septins
keywords: Actin; MAP4; Microtubules; Primary cilium; Septins