Zebrafish ift57, ift88, and ift172 intraflagellar transport mutants disrupt cilia but do not affect hedgehog signaling

Lunt, Shannon; Haynes, Tony E.; Perkins, Brian D.

doi:10.1002/dvdy.21999

Cited by 66 publications

(69 citation statements)

References 91 publications

(142 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Whereas the requirement of IFT proteins for proper Hh signaling in mice is well documented (36 -39), such dependence in zebrafish remains uncertain. A study in zebrafish lacking cilia has suggested a dampening of Hh signaling (40) while another reported no signaling effect in IFT mutant and morphant fish (41). Here, we detected a mild effect of Pol MO on slow muscle development, on Pax2 expression but no effect on Nkx2.2.…”

Section: Discussionsupporting

confidence: 37%

Growth Arrest Specific 8 (Gas8) and G Protein-coupled Receptor Kinase 2 (GRK2) Cooperate in the Control of Smoothened Signaling

Evron

Philipp

Lü

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

The G protein-coupled receptor (GPCR)-like molecule Smoothened (Smo) undergoes dynamic intracellular trafficking modulated by the microtubule associated kinase GRK2 and recruitment of ␤-arrestin. Of this trafficking, especially the translocation of Smo into primary cilia and back to the cytoplasm is essential for the activation of Hedgehog (Hh) signaling in vertebrates. The complete mechanism of this bidirectional transport, however, is not completely understood. Here we demonstrate that Growth Arrest Specific 8 (Gas8), a microtubule associated subunit of the Dynein Regulatory Complex (DRC), interacts with Smo to modulate this process. Gas8 knockdown in ciliated cells reduces Smo signaling activity and ciliary localization whereas overexpression stimulates Smo activity in a GRK2-dependent manner. The C terminus of Gas8 is important for both Gas8 interaction with Smo and facilitating Smo signaling. In zebrafish, knocking down Gas8 results in attenuated Hh transcriptional responses and impaired early muscle development. These effects can be reversed by the co-injection of Gas8 mRNA or by constitutive activation of the downstream Gli transcription factors. Furthermore, Gas8 and GRK2 display a synergistic effect on zebrafish early muscle development and some effects of GRK2 knockdown can be rescued by Gas8 mRNA. Interestingly, Gas8 does not interfere with cilia assembly, as the primary cilia architecture is unchanged upon Gas8 knock down or heterologous expression. This is in contrast to cells stably expressing both GRK2 and Smo, in which cilia are significantly elongated. These results identify Gas8 as a positive regulator of Hh signaling that cooperates with GRK2 to control Smo signaling. Smoothened (Smo)5 is a G protein-coupled receptor (GPCR)-like protein that serves as the main transducer of the Hedgehog (Hh) signaling pathway, regulating many aspects of embryonic development. Loss of function of components of this pathway leads to human developmental disorders, including holoprosencephaly, polydactyly, craniofacial, and skeletal malformation (1, 2), while inappropriate activation of the pathway is linked to a wide range of malignancies (3). Data from mammalian cell culture, mice, and zebrafish have implicated Smo trafficking into the primary cilia by intraflagellar transport (IFT) particles as an essential step in Hh downstream signaling (reviewed in Refs. 4, 5). Smo translocation results in the accumulation of transcriptionally active Gli (GliA) at the tip of the cilia, which is then transported out of the cilia to promote Hh target gene expression (4). Similar to classic GPCRs, phosphorylation of active Smo by the GPCR kinase 2 (GRK2) and recruitment of ␤-arrestin results in Smo internalization (6), and both GRK2 and ␤-arrestin play a positive role in Smo signaling as they do in selective forms of GPCR signaling (7,8). Interestingly, GRK2 has been reported as a microtubule associated kinase that directly phosphorylates tubulin following GPCR stimulation (9). GRK2 has also been shown to promote signaling thro...

show abstract

Section: Discussionsupporting

confidence: 37%

Growth Arrest Specific 8 (Gas8) and G Protein-coupled Receptor Kinase 2 (GRK2) Cooperate in the Control of Smoothened Signaling

Evron

Philipp

Lü

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Interestingly, although maternal ift57 transcripts decay by 33 hpf in mutants ( Figure 1D), previous studies indicate that Ift57 protein can be detected at 48 hpf, but not at 4 dpf, in ift57 hi3417 mutants. 26,34 Together, these results suggest that maternally supplied Ift57 protein or transcript can persist for an extensive period of time. Consistent with the gradual degradation of maternal gene products, cilia assembly is initially present on the first day of development in ift57 hi3417 and ift172 hi2211 mutants, but is lost at later stages of development.…”

Section: The Role Of Ift Genes In Cilia Assembly In Zebrafishmentioning

confidence: 75%

“…14,15,26 Because cilia formation starts at different time points in different organs, the differences observed may be attributed to the gradual decay of maternally deposited gene products. Early in development, cilia are able to form using maternally contributed gene products, whereas later in development, with the decay of maternal contribution, cilia are unable to form.…”

Section: Cilia Formation Is Affected In Ift57 and Ift172 Mutants In Amentioning

confidence: 99%

Intraflagellar Transport Proteins Are Essential for Cilia Formation and for Planar Cell Polarity

Cao

Park

Sun

2010

Journal of the American Society of Nephrology

View full text Add to dashboard Cite

The highly conserved intraflagellar transport (IFT) proteins are essential for cilia formation in multiple organisms, but surprisingly, cilia form in multiple zebrafish ift mutants. Here, we detected maternal deposition of ift gene products in zebrafish and found that ciliary assembly occurs only during early developmental stages, supporting the idea that maternal contribution of ift gene products masks the function of IFT proteins during initial development. In addition, the basal bodies in multiciliated cells of the pronephric duct in ift mutants were disorganized, with a pattern suggestive of defective planar cell polarity (PCP). Depletion of pk1, a core PCP component, similarly led to kidney cyst formation and basal body disorganization. Furthermore, we found that multiple ift genes genetically interact with pk1. Taken together, these data suggest that IFT proteins play a conserved role in cilia formation and planar cell polarity in zebrafish.

show abstract

“…Genetic studies have shown that a variety of proteins required for ciliogenesis, including the intraflagellar transport (IFT) machinery and basal body proteins that promote cilia formation and maintenance, are essential for all responses to mammalian Hedgehog (Hh) ligands in both early embryos and all other cell types that have been tested (11)(12)(13)(14). In contrast, IFT proteins are not required for Hh signaling in Drosophila, and the role of cilia in the zebrafish pathway is controversial (15,16). In the mouse, it appears that all of the core pathway proteins required for the response to Shh are associated with the cilium.…”

mentioning

confidence: 99%

Mouse Kif7/Costal2 is a cilia-associated protein that regulates Sonic hedgehog signaling

Liem

He²,

Ocbina³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

256

280

View full text Add to dashboard Cite

Mammalian Sonic hedgehog (Shh) signaling is essential for embryonic development and stem cell maintenance and has critical roles in tumorigenesis. Although core components of the Shh pathway are conserved in evolution, important aspects of mammalian Shh signaling are not shared with the Drosophila pathway. Perhaps the most dramatic difference between the Drosophila and mammalian pathways is that Shh signaling in the mouse requires a microtubule-based organelle, the primary cilium. Proteins that are required for the response to Shh are enriched in the cilium, but it is not clear why the cilium provides an appropriate venue for signal transduction. Here, we demonstrate that Kif7, a mammalian homologue of Drosophila Costal2 (Cos2), is a cilia-associated protein that regulates signaling from the membrane protein Smoothened (Smo) to Gli transcription factors. By using a Kif7 mutant allele identified in a reporter-based genetic screen, we show that, similar to Drosophila and zebrafish Cos2, mouse Kif7 acts downstream of Smo and upstream of Gli2 and has both negative and positive roles in Shh signal transduction. Mouse Kif7 activity depends on the presence of cilia and Kif7-eGFP localizes to base of the primary cilium in the absence of Shh. Activation of the Shh pathway promotes trafficking of Kif7-eGFP from the base to the tip of the cilium, and localization to the tip of the cilium is disrupted in a motor domain mutant. We conclude that Kif7 is a core regulator of Shh signaling that may also act as a ciliary motor.Gli2 ͉ intraflagellar transport ͉ smoothened ͉ neural tube ͉ ENU

show abstract

Zebrafish ift57, ift88, and ift172 intraflagellar transport mutants disrupt cilia but do not affect hedgehog signaling

Cited by 66 publications

References 91 publications

Growth Arrest Specific 8 (Gas8) and G Protein-coupled Receptor Kinase 2 (GRK2) Cooperate in the Control of Smoothened Signaling

Growth Arrest Specific 8 (Gas8) and G Protein-coupled Receptor Kinase 2 (GRK2) Cooperate in the Control of Smoothened Signaling

Intraflagellar Transport Proteins Are Essential for Cilia Formation and for Planar Cell Polarity

Mouse Kif7/Costal2 is a cilia-associated protein that regulates Sonic hedgehog signaling

Contact Info

Product

Resources

About