The transition zone protein Rpgrip1l regulates proteasomal activity at the primary cilium.
Bottom Line: Mutations in RPGRIP1L result in severe human diseases called ciliopathies.Indeed, we detected a cilia-dependent decreased proteasomal activity in the absence of Rpgrip1l.We found different proteasomal components localized to cilia and identified Psmd2, a component of the regulatory proteasomal 19S subunit, as an interaction partner for Rpgrip1l.
Affiliation: Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany Christoph.Gerhardt@hhu.de.Show MeSH
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Mentions: A prerequisite for a proteasome to function at the base of cilia is the presence of components of the 19S and 20S proteasomal subunits. Psmd2, Psmd3, and Psmd4, which are components of the 19S proteasomal subunit, are found at the BB of WT MEF cilia by using 3D-SIM (Fig. 5, A–C), supporting the assumed existence of a ciliary proteasome. Psma5, which is a component of the 20S proteasomal subunit is detected at the ciliary base (BB as well as TZ) and along the axoneme of WT MEFs (Fig. 5, D and E), indicating a transport of Psma5 through the cilium. Assuming a transport of Psma5 along the cilium, we propose the BB as the location were the ciliary proteasome localizes and functions. This is the most likely scenario because we never detected components of the 19S proteasomal subunit along the axoneme of MEF cilia.
Affiliation: Institute for Animal Developmental and Molecular Biology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany Christoph.Gerhardt@hhu.de.