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The nphp-2 and arl-13 genetic modules interact to regulate ciliogenesis and ciliary microtubule patterning in C. elegans.

Warburton-Pitt SR, Silva M, Nguyen KC, Hall DH, Barr MM - PLoS Genet. (2014)

Bottom Line: The ciliary targeting and restricted localization of NPHP-2, ARL-13, and UNC-119 does not require TZ-, doublet region, and InvC-associated genes.NPHP-2 does require its calcium binding EF hand domain for targeting to the InvC.We conclude that the C. elegans InvC is distinct from the doublet region, and that components in these two regions interact to regulate ciliogenesis via cilia placement, ciliary microtubule ultrastructure, and protein localization.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America.

ABSTRACT
Cilia are microtubule-based cellular organelles that mediate signal transduction. Cilia are organized into several structurally and functionally distinct compartments: the basal body, the transition zone (TZ), and the cilia shaft. In vertebrates, the cystoprotein Inversin localizes to a portion of the cilia shaft adjacent to the TZ, a region termed the "Inversin compartment" (InvC). The mechanisms that establish and maintain the InvC are unknown. In the roundworm C. elegans, the cilia shafts of amphid channel and phasmid sensory cilia are subdivided into two regions defined by different microtubule ultrastructure: a proximal doublet-based region adjacent to the TZ, and a distal singlet-based region. It has been suggested that C. elegans cilia also possess an InvC, similarly to mammalian primary cilia. Here we explored the biogenesis, structure, and composition of the C. elegans ciliary doublet region and InvC. We show that the InvC is conserved and distinct from the doublet region. nphp-2 (the C. elegans Inversin homolog) and the doublet region genes arl-13, klp-11, and unc-119 are redundantly required for ciliogenesis. InvC and doublet region genes can be sorted into two modules-nphp-2+klp-11 and arl-13+unc-119-which are both antagonized by the hdac-6 deacetylase. The genes of this network modulate the sizes of the NPHP-2 InvC and ARL-13 doublet region. Glutamylation, a tubulin post-translational modification, is not required for ciliary targeting of InvC and doublet region components; rather, glutamylation is modulated by nphp-2, arl-13, and unc-119. The ciliary targeting and restricted localization of NPHP-2, ARL-13, and UNC-119 does not require TZ-, doublet region, and InvC-associated genes. NPHP-2 does require its calcium binding EF hand domain for targeting to the InvC. We conclude that the C. elegans InvC is distinct from the doublet region, and that components in these two regions interact to regulate ciliogenesis via cilia placement, ciliary microtubule ultrastructure, and protein localization.

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Model of the composition of the proximal cilium.ARL-13 is depicted as membrane associated based on published characterizations [37]. NPHP-2 is depicted as membrane associated based on the membrane association of Inversin in mammalian primary cilia, and because in C. elegans NPHP-2 reporters appear membrane associated by casual observation [12], [17]. Kinesin-II is microtubule associated, and UNC-119 is depicted nonspecifically because of the diffuse localization of GFP::UNC-119. Poly-glutamylated tubulin is depicted as a modification of the B-tubule, as reported [45].
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pgen-1004866-g009: Model of the composition of the proximal cilium.ARL-13 is depicted as membrane associated based on published characterizations [37]. NPHP-2 is depicted as membrane associated based on the membrane association of Inversin in mammalian primary cilia, and because in C. elegans NPHP-2 reporters appear membrane associated by casual observation [12], [17]. Kinesin-II is microtubule associated, and UNC-119 is depicted nonspecifically because of the diffuse localization of GFP::UNC-119. Poly-glutamylated tubulin is depicted as a modification of the B-tubule, as reported [45].

Mentions: The C. elegans doublet region and the mammalian proximal InvC have been considered analogous [11], [13], [17], [34], [37]. In C. elegans, a number of factors have been associated with the doublet region, including NPHP-2, ARL-13, UNC-119, ARL-3, HDAC-6, the Kinesin-II components KAP-1/KLP-11/KLP-20 [35]–[37], and glutamylated tubulin [50]. However, mammalian orthologs of many C. elegans doublet region proteins localize along the entire cilium [26], [62]–[71]; this casts doubt on the equivalence between the C. elegans doublet region and the mammalian InvC. It is likely that the C. elegans ciliary doublet region is analogous to the entire mammalian ciliary doublet-based cilia shaft, and that the mammalian InvC is analogous to a C. elegans InvC (modelled in Fig. 9).


The nphp-2 and arl-13 genetic modules interact to regulate ciliogenesis and ciliary microtubule patterning in C. elegans.

Warburton-Pitt SR, Silva M, Nguyen KC, Hall DH, Barr MM - PLoS Genet. (2014)

Model of the composition of the proximal cilium.ARL-13 is depicted as membrane associated based on published characterizations [37]. NPHP-2 is depicted as membrane associated based on the membrane association of Inversin in mammalian primary cilia, and because in C. elegans NPHP-2 reporters appear membrane associated by casual observation [12], [17]. Kinesin-II is microtubule associated, and UNC-119 is depicted nonspecifically because of the diffuse localization of GFP::UNC-119. Poly-glutamylated tubulin is depicted as a modification of the B-tubule, as reported [45].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263411&req=5

pgen-1004866-g009: Model of the composition of the proximal cilium.ARL-13 is depicted as membrane associated based on published characterizations [37]. NPHP-2 is depicted as membrane associated based on the membrane association of Inversin in mammalian primary cilia, and because in C. elegans NPHP-2 reporters appear membrane associated by casual observation [12], [17]. Kinesin-II is microtubule associated, and UNC-119 is depicted nonspecifically because of the diffuse localization of GFP::UNC-119. Poly-glutamylated tubulin is depicted as a modification of the B-tubule, as reported [45].
Mentions: The C. elegans doublet region and the mammalian proximal InvC have been considered analogous [11], [13], [17], [34], [37]. In C. elegans, a number of factors have been associated with the doublet region, including NPHP-2, ARL-13, UNC-119, ARL-3, HDAC-6, the Kinesin-II components KAP-1/KLP-11/KLP-20 [35]–[37], and glutamylated tubulin [50]. However, mammalian orthologs of many C. elegans doublet region proteins localize along the entire cilium [26], [62]–[71]; this casts doubt on the equivalence between the C. elegans doublet region and the mammalian InvC. It is likely that the C. elegans ciliary doublet region is analogous to the entire mammalian ciliary doublet-based cilia shaft, and that the mammalian InvC is analogous to a C. elegans InvC (modelled in Fig. 9).

Bottom Line: The ciliary targeting and restricted localization of NPHP-2, ARL-13, and UNC-119 does not require TZ-, doublet region, and InvC-associated genes.NPHP-2 does require its calcium binding EF hand domain for targeting to the InvC.We conclude that the C. elegans InvC is distinct from the doublet region, and that components in these two regions interact to regulate ciliogenesis via cilia placement, ciliary microtubule ultrastructure, and protein localization.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America.

ABSTRACT
Cilia are microtubule-based cellular organelles that mediate signal transduction. Cilia are organized into several structurally and functionally distinct compartments: the basal body, the transition zone (TZ), and the cilia shaft. In vertebrates, the cystoprotein Inversin localizes to a portion of the cilia shaft adjacent to the TZ, a region termed the "Inversin compartment" (InvC). The mechanisms that establish and maintain the InvC are unknown. In the roundworm C. elegans, the cilia shafts of amphid channel and phasmid sensory cilia are subdivided into two regions defined by different microtubule ultrastructure: a proximal doublet-based region adjacent to the TZ, and a distal singlet-based region. It has been suggested that C. elegans cilia also possess an InvC, similarly to mammalian primary cilia. Here we explored the biogenesis, structure, and composition of the C. elegans ciliary doublet region and InvC. We show that the InvC is conserved and distinct from the doublet region. nphp-2 (the C. elegans Inversin homolog) and the doublet region genes arl-13, klp-11, and unc-119 are redundantly required for ciliogenesis. InvC and doublet region genes can be sorted into two modules-nphp-2+klp-11 and arl-13+unc-119-which are both antagonized by the hdac-6 deacetylase. The genes of this network modulate the sizes of the NPHP-2 InvC and ARL-13 doublet region. Glutamylation, a tubulin post-translational modification, is not required for ciliary targeting of InvC and doublet region components; rather, glutamylation is modulated by nphp-2, arl-13, and unc-119. The ciliary targeting and restricted localization of NPHP-2, ARL-13, and UNC-119 does not require TZ-, doublet region, and InvC-associated genes. NPHP-2 does require its calcium binding EF hand domain for targeting to the InvC. We conclude that the C. elegans InvC is distinct from the doublet region, and that components in these two regions interact to regulate ciliogenesis via cilia placement, ciliary microtubule ultrastructure, and protein localization.

Show MeSH
Related in: MedlinePlus