RABL2 interacts with the intraflagellar transport-B complex and CEP19 and participates in ciliary assembly

Nishijima, Yuya; Hagiya, Yohei; Kubo, Tomohiro; Takei, Ryota; Katoh, Yohei; Nakayama, Kazuhisa

doi:10.1091/mbc.e17-01-0017

Cited by 81 publications

(116 citation statements)

References 47 publications

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“…Rabl2 is an atypical Rab small GTPase that promotes anterograde IFT from the ciliary base 26,[32][33][34] . Recently, we have shown that Rabl2 is required for ciliary targeting of Htr6 and Gpr161, with which it interacts 26 .…”

Section: Htr6 Cts1 and Cts2 Contribute To Rabl2 Bindingmentioning

confidence: 99%

Htr6 and Sstr3 ciliary targeting relies on both IC3 loops and C-terminal tails

Barbeito

Tachibana

Martin-Morales

et al. 2020

Preprint

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G protein-coupled receptors (GPCRs) are the most common pharmacological target in clinical practice. To perform their signaling functions, many GPCRs must accumulate at primary cilia, microtubule-based plasma membrane protrusions that work as cellular antennae. Despite their great importance, the molecular mechanisms underlying GPCR ciliary targeting remain poorly understood. Serotonin receptor 6 (Htr6) and somatostatin receptor 3 (Sstr3) are two brain-enriched ciliary GPCRs controlling cognition and involved in multiple pathologies such as Alzheimer's disease and cancer. We previously showed that the third intracellular loops (IC3s) of Htr6 and Sstr3 contain ciliary targeting sequences (CTSs) that are sufficient to confer ciliary localization to non-ciliary GPCRs. However, these CTSs are dispensable for the ciliary targeting of Htr6 and Sstr3 themselves, suggesting these GPCRs have additional CTSs. Herein, we show that the C-terminal tails of Htr6 and Sstr3 also contain CTSs, which act redundantly with those in the IC3s. Accordingly, simultaneous disruption of CTS1 (IC3) and CTS2 (C-terminal tail) abolishes ciliary targeting of both receptors. Mapping the individual residues required for Htr6 ciliary targeting reveals RKQ and LPG motifs critical for CTS1 and CTS2 function, respectively. In Sstr3, CTS1 function relies on the tandem AP[AS]CQ motifs and a subsequent arginine-rich stretch, whereas CTS2 operation requires the juxtamembrane residues. Furthermore, we shed light on the mechanisms of action of Htr6 CTSs by showing how they regulate binding to Tulp3 and Rabl2, two adapters needed for ciliary GPCR targeting. 3 (IC3s). This was first found for Sstr3 and Htr6 and was later extended to others like Mchr1, Gpr161, Mc4r or Npy2r 9,[20][21][22][23] .For Sstr3 and Htr6, their CTSs were discovered by generating chimeras between these ciliary GPCRs and their non-ciliary relatives Sstr5 and Htr7. After extensive analyses, replacing the IC3s of Sstr5 or Htr7 with those of Sstr3 or Htr6, respectively, was found to suffice for ciliary targeting of the nonciliary receptors. Furthermore, ciliary targeting of these chimeras was abolished by mutating to phenylalanine the first and last residues of Ax[AS]xQ motifs (hereafter referred to as A-Q motifs) present in the IC3s of both Sstr3 and Htr6 20 . In this study, another interesting observation was noted: the reverse pair of chimeras, in which the IC3s of Sstr3 and Htr6 were replaced by those of Sstr5 and Htr7, still accumulated in cilia, indicating that the newly discovered CTSs, albeit sufficient for ciliary targeting of non-ciliary receptors, were dispensable for ciliary targeting of Sstr3 and Htr6 themselves. This suggested, it was also noted, the presence of additional CTSs in these receptors 20 . A subsequent study confirmed that Htr6 IC3 is dispensable for its ciliary targeting 16 .Herein, we report the identification and characterization of those missing CTSs. We show that, for both Sstr3 and Htr6, ciliary targeting occurs as long as either IC3, CT, or both, are pre...

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Section: Htr6 Cts1 and Cts2 Contribute To Rabl2 Bindingmentioning

confidence: 99%

Htr6 and Sstr3 ciliary targeting relies on both IC3 loops and C-terminal tails

Barbeito

Tachibana

Martin-Morales

et al. 2020

Preprint

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“…In mammalian cilia, IFT27 was shown to be required for exit of the BBSome complex and associated ciliary cargoes (Keady et al, 2012;Eguether et al, 2014). Recently, Rabl2 was identified as a potential third Rab-like member of the IFT complex as it was shown to regulate IFT initiation and to associate with the IFT74/81 sub-complex Kanie et al, 2017;Nishijima et al, 2017). Interestingly, IFT22 and IFT27 also associate with the IFT74/81 subcomplex (Taschner et al, 2014) suggesting that IFT22, IFT27, and Rabl2 may be located within close proximity in the IFT B1 complex.…”

Section: Introductionmentioning

confidence: 99%

Binding of IFT22 to the intraflagellar transport complex is essential for flagellum assembly

et al. 2019

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Intraflagellar transport (IFT) relies on motor proteins and the IFT complex to construct cilia and flagella. The IFT complex subunit IFT22/RabL5 has sequence similarity with small GTPases although the nucleotide specificity is unclear because of non‐conserved G4/G5 motifs. We show that IFT22 specifically associates with G‐nucleotides and present crystal structures of IFT22 in complex with GDP, GTP, and with IFT74/81. Our structural analysis unravels an unusual GTP/GDP‐binding mode of IFT22 bypassing the classical G4 motif. The GTPase switch regions of IFT22 become ordered upon complex formation with IFT74/81 and mediate most of the IFT22‐74/81 interactions. Structure‐based mutagenesis reveals that association of IFT22 with the IFT complex is essential for flagellum construction in Trypanosoma brucei although IFT22 GTP‐loading is not strictly required.

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“…S5, d=334±38nm (our data); d=372.6±16.4nm 77 ). This 346 observation is supported by recent evidence suggesting that CEP19 forms a functional complex 347 with FOP and CEP350, distal appendage proteins required for an early step of ciliogenesis 77,78,79 . 348…”

Section: The Architecture Of the Basal Foot Revealed By Super-resolutmentioning

confidence: 66%

Super-resolution Molecular Map of Basal Foot Reveals Novel Cilium in Airway Multiciliated Cells

Nguyen

Liu

Nanjundappa³

et al. 2018

Preprint

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33Motile cilia are beating machines that play a critical role in airway defense. During airway 34 cell differentiation, hundreds of motile cilia are templated from basal bodies that extend a basal 35 foot, an appendage that links motile cilia together to ensure beating coordination. This assembly 36 has thus far escaped structural analysis because its size is below the resolution limit. Here, we 37 determine the molecular architecture and identify basal foot proteins using a super-resolution-38 driven approach. Quantitative super-resolution image analysis shows that the basal foot is 39 organized in three main regions linked by elongated coiled-coil proteins. FIB-SEM tomography 40 and comparative super-resolution mapping of basal feet reveal that, among hundreds of motile 41 cilia of an airway cell, a hybrid cilium with features of primary and motile cilia is harbored. The 42 hybrid cilium is conserved in mammalian multiciliated cells and originates from parental 43 centrioles. We further demonstrate that this novel cilium is a signalling centre whose cellular 44 position is dependent on flow. 45 46 47 48 49 50 51 52 53 54 55 56

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RABL2 interacts with the intraflagellar transport-B complex and CEP19 and participates in ciliary assembly

Cited by 81 publications

References 47 publications

Htr6 and Sstr3 ciliary targeting relies on both IC3 loops and C-terminal tails

Htr6 and Sstr3 ciliary targeting relies on both IC3 loops and C-terminal tails

Binding of IFT22 to the intraflagellar transport complex is essential for flagellum assembly

Super-resolution Molecular Map of Basal Foot Reveals Novel Cilium in Airway Multiciliated Cells

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