scholarly journals Tetrahymena Poc1 ensures proper intertriplet microtubule linkages to maintain basal body integrity

2016 ◽  
Vol 27 (15) ◽  
pp. 2394-2403 ◽  
Author(s):  
Janet B. Meehl ◽  
Brian A. Bayless ◽  
Thomas H. Giddings ◽  
Chad G. Pearson ◽  
Mark Winey
Keyword(s):  
Basal Body ◽  
Electron Tomography ◽  
Force Distribution ◽  
Basal Bodies ◽  
Unknown Mechanism ◽  
Ciliary Beating ◽  
Beat Pattern ◽  
Motile Cilia ◽  
Microtubule Structure

Basal bodies comprise nine symmetric triplet microtubules that anchor forces produced by the asymmetric beat pattern of motile cilia. The ciliopathy protein Poc1 stabilizes basal bodies through an unknown mechanism. In poc1∆ cells, electron tomography reveals subtle defects in the organization of intertriplet linkers (A-C linkers) that connect adjacent triplet microtubules. Complete triplet microtubules are lost preferentially near the posterior face of the basal body. Basal bodies that are missing triplets likely remain competent to assemble new basal bodies with nine triplet microtubules, suggesting that the mother basal body microtubule structure does not template the daughter. Our data indicate that Poc1 stabilizes basal body triplet microtubules through linkers between neighboring triplets. Without this stabilization, specific triplet microtubules within the basal body are more susceptible to loss, probably due to force distribution within the basal body during ciliary beating. This work provides insights into how the ciliopathy protein Poc1 maintains basal body integrity.

scholarly journals Asymmetrically localized proteins stabilize basal bodies against ciliary beating forces

2016 ◽  
Vol 215 (4) ◽  
pp. 457-466 ◽  
Author(s):  
Brian A. Bayless ◽  
Domenico F. Galati ◽  
Anthony D. Junker ◽  
Chelsea B. Backer ◽  
Jacek Gaertig ◽  
...  
Keyword(s):  
Basal Body ◽  
Mechanical Force ◽  
Basal Bodies ◽  
Mechanical Forces ◽  
Ciliary Beating ◽  
Motile Cilia ◽  
Molecular Components

Basal bodies are radially symmetric, microtubule-rich structures that nucleate and anchor motile cilia. Ciliary beating produces asymmetric mechanical forces that are resisted by basal bodies. To resist these forces, distinct regions within the basal body ultrastructure and the microtubules themselves must be stable. However, the molecular components that stabilize basal bodies remain poorly defined. Here, we determine that Fop1 functionally interacts with the established basal body stability components Bld10 and Poc1. We find that Fop1 and microtubule glutamylation incorporate into basal bodies at distinct stages of assembly, culminating in their asymmetric enrichment at specific triplet microtubule regions that are predicted to experience the greatest mechanical force from ciliary beating. Both Fop1 and microtubule glutamylation are required to stabilize basal bodies against ciliary beating forces. Our studies reveal that microtubule glutamylation and Bld10, Poc1, and Fop1 stabilize basal bodies against the forces produced by ciliary beating via distinct yet interdependent mechanisms.

scholarly journals Bld10/Cep135 stabilizes basal bodies to resist cilia-generated forces

2012 ◽  
Vol 23 (24) ◽  
pp. 4820-4832 ◽  
Author(s):  
Brian A. Bayless ◽  
Thomas H. Giddings ◽  
Mark Winey ◽  
Chad G. Pearson
Keyword(s):  
Basal Body ◽  
Structural Integrity ◽  
Basal Bodies ◽  
Ciliary Beating ◽  
Full Complement ◽  
Domain Protein ◽  
Motile Cilia ◽  
The Stability

Basal bodies nucleate, anchor, and organize cilia. As the anchor for motile cilia, basal bodies must be resistant to the forces directed toward the cell as a consequence of ciliary beating. The molecules and generalized mechanisms that contribute to the maintenance of basal bodies remain to be discovered. Bld10/Cep135 is a basal body outer cartwheel domain protein that has established roles in the assembly of nascent basal bodies. We find that Bld10 protein first incorporates stably at basal bodies early during new assembly. Bld10 protein continues to accumulate at basal bodies after assembly, and we hypothesize that the full complement of Bld10 is required to stabilize basal bodies. We identify a novel mechanism for Bld10/Cep135 in basal body maintenance so that basal bodies can withstand the forces produced by motile cilia. Bld10 stabilizes basal bodies by promoting the stability of the A- and C-tubules of the basal body triplet microtubules and by properly positioning the triplet microtubule blades. The forces generated by ciliary beating promote basal body disassembly in bld10Δ cells. Thus Bld10/Cep135 acts to maintain the structural integrity of basal bodies against the forces of ciliary beating in addition to its separable role in basal body assembly.

scholarly journals PACRG and FAP20 form the inner junction of axonemal doublet microtubules and regulate ciliary motility

2019 ◽  
Vol 30 (15) ◽  
pp. 1805-1816 ◽  
Author(s):  
Erin E. Dymek ◽  
Jianfeng Lin ◽  
Gang Fu ◽  
Mary E. Porter ◽  
Daniela Nicastro ◽  
...  
Keyword(s):  
Cell Motility ◽  
Electron Tomography ◽  
Structural Studies ◽  
Ciliary Beating ◽  
Ciliary Motility ◽  
Functional Studies ◽  
Cryo Electron Tomography ◽  
Motile Cilia

We previously demonstrated that PACRG plays a role in regulating dynein-driven microtubule sliding in motile cilia. To expand our understanding of the role of PACRG in ciliary assembly and motility, we used a combination of functional and structural studies, including newly identified Chlamydomonas pacrg mutants. Using cryo-electron tomography we show that PACRG and FAP20 form the inner junction between the A- and B-tubule along the length of all nine ciliary doublet microtubules. The lack of PACRG and FAP20 also results in reduced assembly of inner-arm dynein IDA b and the beak-MIP structures. In addition, our functional studies reveal that loss of PACRG and/or FAP20 causes severe cell motility defects and reduced in vitro microtubule sliding velocities. Interestingly, the addition of exogenous PACRG and/or FAP20 protein to isolated mutant axonemes restores microtubule sliding velocities, but not ciliary beating. Taken together, these studies show that PACRG and FAP20 comprise the inner junction bridge that serves as a hub for both directly modulating dynein-driven microtubule sliding, as well as for the assembly of additional ciliary components that play essential roles in generating coordinated ciliary beating.

scholarly journals Mcidas mutant mice reveal a two-step process for the specification and differentiation of multiciliated cells in mammals

2018 ◽  
Author(s):  
Hao Lu ◽  
Priyanka Anujan ◽  
Feng Zhou ◽  
Yiliu Zhang ◽  
Yan Ling Chong ◽  
...  
Keyword(s):  
Basal Body ◽  
Target Genes ◽  
Initial Step ◽  
Mutant Mice ◽  
Respiratory Disorder ◽  
Basal Bodies ◽  
Cell Cycle Regulators ◽  
Multiciliated Cells ◽  
Motile Cilia ◽  
Body Production

ABSTRACTMotile cilia on multiciliated cells (MCCs) function in fluid clearance over epithelia. Studies with Xenopus embryos and patients with the congenital respiratory disorder reduced generation of multiple motile cilia, have implicated the nuclear protein MCIDAS (MCI), in the transcriptional regulation of MCC specification and differentiation. Recently, a paralogous protein, GMNC, was also shown to be required for MCC formation. Surprisingly, and in contrast to the presently held view, we find that Mci mutant mice can specify MCC precursors. However, these precursors cannot produce multiple basal bodies, and mature into single ciliated cells. We show that MCI is required specifically to induce deuterosome pathway components for the production of multiple basal bodies. Moreover, GMNC and MCI associate differentially with the cell-cycle regulators E2F4 and E2F5, which enables them to activate distinct sets of target genes (ciliary transcription factor genes versus genes for basal body generation). Our data establish a previously unrecognized two-step model for MCC development: GMNC functions in the initial step for MCC precursor specification. GMNC induces Mci expression, which then drives the second step of basal body production for multiciliation.SUMMARY STATEMENTWe show how two GEMININ family proteins function in mammalian multiciliated cell development: GMNC regulates precursor specification and MCIDAS induces multiple basal body formation for multiciliation.

Proteomic analysis of microtubule inner proteins (MIPs) in Rib72 null Tetrahymena cells reveals functional MIPs

2020 ◽  
Author(s):  
Amy S. Fabritius ◽  
Brian A. Bayless ◽  
Sam Li ◽  
Daniel Stoddard ◽  
Westley Heydeck ◽  
...  
Keyword(s):  
Proteomic Analysis ◽  
Tetrahymena Thermophila ◽  
Electron Tomography ◽  
Functional Characterization ◽  
Ciliary Beating ◽  
Ciliary Function ◽  
Cryo Electron Tomography ◽  
Motile Cilia ◽  
Cilia And Flagella ◽  
Stable Populations

AbstractMotile cilia and flagella are built from stable populations of doublet microtubules that comprise their axonemes. Their unique stability is brought about, at least in part, by a network of Microtubule Inner Proteins (MIPs) found in the lumen of their doublet microtubules. Rib72A and Rib72B were identified as microtubule inner proteins (MIPs) in the motile cilia of Tetrahymena thermophila. Loss of these proteins leads to ciliary defects and loss of multiple MIPs. We performed mass spectrometry coupled with proteomic analysis and bioinformatics to identify the MIPs lost in RIB72A/B knockout (KO) Tetrahymena cells. From this analysis we identified a number of candidate MIPs and pursued one, Fap115, for functional characterization. We find that loss of Fap115 results in disrupted cell swimming and aberrant ciliary beating. Cryo-electron tomography reveals that Fap115 localizes to MIP6a in the A-tubule of the doublet microtubules. Overall, our results highlight the complex relationship between MIPs, ciliary structure, and ciliary function.

scholarly journals Three-dimensional Organization of Basal Bodies from Wild-Type and δ-Tubulin Deletion Strains of Chlamydomonas reinhardtii

2003 ◽  
Vol 14 (7) ◽  
pp. 2999-3012 ◽  
Author(s):  
Eileen T. O'Toole ◽  
Thomas H. Giddings ◽  
J. Richard McIntosh ◽  
Susan K. Dutcher
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Specimen Preparation ◽  
Basal Bodies ◽  
Wild Type ◽  
Tubulin Isoforms ◽  
Striated Fiber ◽  
And Function

Improved methods of specimen preparation and dual-axis electron tomography have been used to study the structure and organization of basal bodies in the unicellular alga Chlamydomonas reinhardtii. Novel structures have been found in both wild type and strains with mutations that affect specific tubulin isoforms. Previous studies have shown that strains lacking δ-tubulin fail to assemble the C-tubule of the basal body. Tomographic reconstructions of basal bodies from the δ-tubulin deletion mutant uni3-1 have confirmed that basal bodies contain mostly doublet microtubules. Our methods now show that the stellate fibers, which are present only in the transition zone of wild-type cells, repeat within the core of uni3-1 basal bodies. The distal striated fiber is incomplete in this mutant, rootlet microtubules can be misplaced, and multiflagellate cells have been observed. A suppressor of uni3-1, designated tua2-6, contains a mutation in α-tubulin. tua2-6; uni3-1 cells build both flagella, yet they retain defects in basal body structure and in rootlet microtubule positioning. These data suggest that the presence of specific tubulin isoforms in Chlamydomonas directly affects the assembly and function of both basal bodies and basal body-associated structures.

scholarly journals Emerging Picture of Deuterosome-Dependent Centriole Amplification in MCCs

Cells ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 152 ◽  
Author(s):  
Umama Shahid ◽  
Priyanka Singh
Keyword(s):  
Basal Body ◽  
De Novo ◽  
Super Resolution ◽  
Basal Bodies ◽  
Parallel Pathways ◽  
Multiciliated Cells ◽  
Dependent Pathway ◽  
Microtubule Structure

Multiciliated cells (MCCs) have several hair-like structures called cilia, which are required to propel substances on their surface. A cilium is organized from a basal body which resembles a hollow microtubule structure called a centriole. In terminally differentiated MCCs, hundreds of new basal bodies/centrioles are formed via two parallel pathways: the centriole- and deuterosome-dependent pathways. The deuterosome-dependent pathway is also referred to as “de novo” because unlike the centriole-dependent pathway which requires pre-existing centrioles, in the de novo pathway multiple new centrioles are organized around non-microtubule structures called deuterosomes. In the last five years, some deuterosome-specific markers have been identified and concurrent advancements in the super-resolution techniques have significantly contributed to gaining insights about the major stages of centriole amplification during ciliogenesis. Altogether, a new picture is emerging which also challenges the previous notion that deuterosome pathway is de novo. This review is primarily focused on studies that have contributed towards the better understanding of deuterosome-dependent centriole amplification and presents a developing model about the major stages identified during this process.

scholarly journals The molecular dynamics of subdistal appendages in multi-ciliated cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hyunchul Ryu ◽  
Haeryung Lee ◽  
Jiyeon Lee ◽  
Hyuna Noh ◽  
Miram Shin ◽  
...  
Keyword(s):  
Basal Body ◽  
Ependymal Cells ◽  
Basal Bodies ◽  
Ciliary Beating ◽  
Sam Domain ◽  
Adult Mice ◽  
Region I ◽  
Evolutionarily Conserved ◽  
Basal Foot

AbstractThe motile cilia of ependymal cells coordinate their beats to facilitate a forceful and directed flow of cerebrospinal fluid (CSF). Each cilium originates from a basal body with a basal foot protruding from one side. A uniform alignment of these basal feet is crucial for the coordination of ciliary beating. The process by which the basal foot originates from subdistal appendages of the basal body, however, is unresolved. Here, we show FGFR1 Oncogene Partner (FOP) is a useful marker for delineating the transformation of a circular, unpolarized subdistal appendage into a polarized structure with a basal foot. Ankyrin repeat and SAM domain-containing protein 1A (ANKS1A) interacts with FOP to assemble region I of the basal foot. Importantly, disruption of ANKS1A reduces the size of region I. This produces an unstable basal foot, which disrupts rotational polarity and the coordinated beating of cilia in young adult mice. ANKS1A deficiency also leads to severe degeneration of the basal foot in aged mice and the detachment of cilia from their basal bodies. This role of ANKS1A in the polarization of the basal foot is evolutionarily conserved in vertebrates. Thus, ANKS1A regulates FOP to build and maintain the polarity of subdistal appendages.

scholarly journals Ciliary force-responsive striated fibers promote basal body connections and cortical interactions

2019 ◽  
Vol 219 (1) ◽  
Author(s):  
Adam W.J. Soh ◽  
Teunis J.P. van Dam ◽  
Alexander J. Stemm-Wolf ◽  
Andrew T. Pham ◽  
Garry P. Morgan ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Steady State ◽  
Basal Body ◽  
Basal Bodies ◽  
Cellular Motility ◽  
Dynamic Regulation ◽  
Normal Orientation ◽  
Motile Cilia ◽  
Family Loss ◽  
Dependent Mechanism

Multi-ciliary arrays promote fluid flow and cellular motility using the polarized and coordinated beating of hundreds of motile cilia. Tetrahymena basal bodies (BBs) nucleate and position cilia, whereby BB-associated striated fibers (SFs) promote BB anchorage and orientation into ciliary rows. Mutants that shorten SFs cause disoriented BBs. In contrast to the cytotaxis model, we show that disoriented BBs with short SFs can regain normal orientation if SF length is restored. In addition, SFs adopt unique lengths by their shrinkage and growth to establish and maintain BB connections and cortical interactions in a ciliary force-dependent mechanism. Tetrahymena SFs comprise at least eight uniquely localizing proteins belonging to the SF-assemblin family. Loss of different proteins that localize to the SF base disrupts either SF steady-state length or ciliary force-induced SF elongation. Thus, the dynamic regulation of SFs promotes BB connections and cortical interactions to organize ciliary arrays.

scholarly journals Proteomic analysis of microtubule inner proteins (MIPs) in Rib72 null Tetrahymena cells reveals functional MIPs

2021 ◽  
pp. mbc.E20-12-0786
Author(s):  
Amy S. Fabritius ◽  
Brian A. Bayless ◽  
Sam Li ◽  
Daniel Stoddard ◽  
Westley Heydeck ◽  
...  
Keyword(s):  
Proteomic Analysis ◽  
Tetrahymena Thermophila ◽  
Electron Tomography ◽  
Functional Characterization ◽  
Ciliary Beating ◽  
Ciliary Function ◽  
Luminal Side ◽  
Cryo Electron Tomography ◽  
Motile Cilia ◽  
Cilia And Flagella

The core structure of motile cilia and flagella, the axoneme, is built from a stable population of doublet microtubules. This unique stability is brought about, at least in part, by a network of Microtubule Inner Proteins (MIPs) that are bound to the luminal side of the microtubule walls. Rib72A and Rib72B were identified as MIPs in the motile cilia of the protist Tetrahymena thermophila. Loss of these proteins leads to ciliary defects and loss of additional MIPs. We performed mass spectrometry coupled with proteomic analysis and bioinformatics to identify the MIPs lost in RIB72A/B knockout Tetrahymena axonemes. We identified a number of candidate MIPs and pursued one, Fap115, for functional characterization. We find that loss of Fap115 results in disrupted cell swimming and aberrant ciliary beating. Cryo-electron tomography reveals that Fap115 localizes to MIP6a in the A-tubule of the doublet microtubules. Overall, our results highlight the complex relationship between MIPs, ciliary structure, and ciliary function.

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