Compensatory Role of Inositol 5-Phosphatase INPP5B to OCRL in Primary Cilia Formation in Oculocerebrorenal Syndrome of Lowe

Primary cilia act as crucial regulators of embryo development and tissue homeostasis. They are instrumental for modulation of several signaling pathways, including Hedgehog, WNT, and TGF-β. However, gaps exist in our understanding of how cilia formation and function is regulated. Recent work has implicated WNT/β-catenin signaling pathway in the regulation of ciliogenesis, yet the results are conflicting. One model suggests that WNT/β-catenin signaling negatively regulates cilia formation, possibly via effects on cell cycle. In contrast, second model proposes a positive role of WNT/β-catenin signaling on cilia formation, mediated by the re-arrangement of centriolar satellites in response to phosphorylation of the key component of WNT/β-catenin pathway, β-catenin. To clarify these discrepancies, we investigated possible regulation of primary cilia by the WNT/β-catenin pathway in cell lines (RPE-1, NIH3T3, and HEK293) commonly used to study ciliogenesis. We used WNT3a to activate or LGK974 to block the pathway, and examined initiation of ciliogenesis, cilium length, and percentage of ciliated cells. We show that the treatment by WNT3a has no- or lesser inhibitory effect on cilia formation. Importantly, the inhibition of secretion of endogenous WNT ligands using LGK974 blocks WNT signaling but does not affect ciliogenesis. Finally, using knock-out cells for key WNT pathway components, namely DVL1/2/3, LRP5/6, or AXIN1/2 we show that neither activation nor deactivation of the WNT/β-catenin pathway affects the process of ciliogenesis. These results suggest that WNT/β-catenin-mediated signaling is not generally required for efficient cilia formation. In fact, activation of the WNT/β-catenin pathway in some systems seems to moderately suppress ciliogenesis.

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Intraflagellar transport is deeply integrated in hedgehog signaling

Molecular Biology of the Cell ◽

10.1091/mbc.e17-10-0600 ◽

2018 ◽

Vol 29 (10) ◽

pp. 1178-1189 ◽

Cited By ~ 18

Author(s):

Thibaut Eguether ◽

Fabrice P. Cordelieres ◽

Gregory J. Pazour

Keyword(s):

Transcription Factors ◽

Membrane Protein ◽

Hedgehog Signaling ◽

Primary Cilia ◽

Intraflagellar Transport ◽

Hedgehog Pathway ◽

Gli Transcription Factors ◽

Cilia Formation ◽

Mutant Cells

The vertebrate hedgehog pathway is organized in primary cilia, and hedgehog components relocate into or out of cilia during signaling. Defects in intraflagellar transport (IFT) typically disrupt ciliary assembly and attenuate hedgehog signaling. Determining whether IFT drives the movement of hedgehog components is difficult due to the requirement of IFT for building cilia. Unlike most IFT proteins, IFT27 is dispensable for cilia formation but affects hedgehog signaling similarly to other IFTs, allowing us to examine its role in the dynamics of signaling. Activating signaling at points along the pathway in Ift27 mutant cells showed that IFT is extensively involved in the pathway. Similar analysis of Bbs mutant cells showed that BBS proteins participate at many levels of signaling but are not needed to concentrate Gli transcription factors at the ciliary tip. Our analysis showed that smoothened delivery to cilia does not require IFT27, but the role of other IFTs is not known. Using a rapamycin-induced dimerization system to sequester IFT-B proteins at the mitochondria in cells with fully formed cilia did not affect the delivery of Smo to cilia, suggesting that this membrane protein may not require IFT-B for delivery.

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Uncoupling Intraflagellar Transport and Primary Cilia Formation Demonstrates Deep Integration of IFT in Hedgehog Signaling

10.1101/226324 ◽

2017 ◽

Author(s):

Thibaut Eguether ◽

Fabrice P Cordelieres ◽

Gregory J Pazour

Keyword(s):

Hedgehog Signaling ◽

Primary Cilia ◽

Intraflagellar Transport ◽

Embryonic Fibroblasts ◽

Fk506 Binding Protein ◽

Gli Transcription Factors ◽

Cilia Formation ◽

Deep Integration ◽

Mutant Cells

AbstractThe vertebrate hedgehog pathway is organized in primary cilia and hedgehog components relocate into or out of cilia during signaling. Defects in intraflagellar transport (IFT) typically disrupt ciliary assembly and attenuate hedgehog signaling. Determining if IFT drives the movement of hedgehog components is difficult due to the requirement of IFT for building cilia. Unlike most IFT proteins, IFT27 is dispensable for cilia formation but affects hedgehog signaling similar to other IFTs allowing us to examine its role in the dynamics of signaling. Activating signaling at points along the pathway inIft27mutant cells showed that IFT is extensively involved in the pathway. Similar analysis ofBbsmutant cells showed that BBS proteins participate at many levels of signaling but are not needed to concentrate Gli transcription factors at the ciliary tip. Our analysis showed that smoothened delivery to cilia does not require IFT27, but the role of other IFTs is not known. Using a rapamycin-induced dimerization system to stop IFT after ciliary assembly was complete we show that smoothened delivery to cilia is IFT independent.AbbreviationsMEFsmouse embryonic fibroblastsSAGsmoothen agonistIFTintraflagellar transportFKBPFK506 Binding Protein 12FRBFKBP12-rapamycin binding

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Primary Cilia in Glial Cells: An Oasis in the Journey to Overcoming Neurodegenerative Diseases

Frontiers in Neuroscience ◽

10.3389/fnins.2021.736888 ◽

2021 ◽

Vol 15 ◽

Author(s):

Soo Mi Ki ◽

Hui Su Jeong ◽

Ji Eun Lee

Keyword(s):

Neurodegenerative Diseases ◽

Glial Cells ◽

Primary Cilia ◽

Regulatory Mechanisms ◽

Close Attention ◽

Cellular Processes ◽

Cilia Formation ◽

And Function ◽

Cellular Organelles

Many neurodegenerative diseases have been associated with defects in primary cilia, which are cellular organelles involved in diverse cellular processes and homeostasis. Several types of glial cells in both the central and peripheral nervous systems not only support the development and function of neurons but also play significant roles in the mechanisms of neurological disease. Nevertheless, most studies have focused on investigating the role of primary cilia in neurons. Accordingly, the interest of recent studies has expanded to elucidate the role of primary cilia in glial cells. Correspondingly, several reports have added to the growing evidence that most glial cells have primary cilia and that impairment of cilia leads to neurodegenerative diseases. In this review, we aimed to understand the regulatory mechanisms of cilia formation and the disease-related functions of cilia, which are common or specific to each glial cell. Moreover, we have paid close attention to the signal transduction and pathological mechanisms mediated by glia cilia in representative neurodegenerative diseases. Finally, we expect that this field of research will clarify the mechanisms involved in the formation and function of glial cilia to provide novel insights and ideas for the treatment of neurodegenerative diseases in the future.

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Dlec1 is required for spermatogenesis and male fertility in mice

Scientific Reports ◽

10.1038/s41598-020-75957-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yu Okitsu ◽

Mamoru Nagano ◽

Takahiro Yamagata ◽

Chizuru Ito ◽

Kiyotaka Toshimori ◽

...

Keyword(s):

Male Fertility ◽

Primary Cilia ◽

Critical Role ◽

Intraflagellar Transport ◽

Suppressor Gene ◽

Tumour Suppressor Gene ◽

Adenocarcinoma Cells ◽

Cilia Formation ◽

Ring Complex

Abstract Deleted in lung and esophageal cancer 1 (DLEC1) is a tumour suppressor gene that is downregulated in various cancers in humans; however, the physiological and molecular functions of DLEC1 are still unclear. This study investigated the critical role of Dlec1 in spermatogenesis and male fertility in mice. Dlec1 was significantly expressed in testes, with dominant expression in germ cells. We disrupted Dlec1 in mice and analysed its function in spermatogenesis and male fertility. Dlec1 deletion caused male infertility due to impaired spermatogenesis. Spermatogenesis progressed normally to step 8 spermatids in Dlec1−/− mice, but in elongating spermatids, we observed head deformation, a shortened tail, and abnormal manchette organization. These phenotypes were similar to those of various intraflagellar transport (IFT)-associated gene-deficient sperm. In addition, DLEC1 interacted with tailless complex polypeptide 1 ring complex (TRiC) and Bardet–Biedl Syndrome (BBS) protein complex subunits, as well as α- and β-tubulin. DLEC1 expression also enhanced primary cilia formation and cilia length in A549 lung adenocarcinoma cells. These findings suggest that DLEC1 is a possible regulator of IFT and plays an essential role in sperm head and tail formation in mice.

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The Role of the Wnt/PCP Formin Daam1 in Renal Ciliogenesis

10.1101/512533 ◽

2019 ◽

Author(s):

Mark E. Corkins ◽

Vanja Krneta-Stankic ◽

Malgorzata Kloc ◽

Pierre D. McCrea ◽

Andrew B. Gladden ◽

...

Keyword(s):

Xenopus Laevis ◽

Primary Cilia ◽

Cyst Formation ◽

Zebrafish Embryos ◽

Waste Products ◽

Multiciliated Cells ◽

Wide Range ◽

Cilia Formation ◽

Canonical Wnt

ABSTRACTKidneys are composed of numerous ciliated epithelial tubules called nephrons. Each nephron functions to reabsorb nutrients and concentrate waste products into urine. Defects in primary cilia are associated with abnormal formation of nephrons and cyst formation in a wide range of kidney disorders. Previous work in Xenopus laevis and zebrafish embryos established that loss of components that make up the Wnt/PCP pathway, Daam1 and ArhGEF19 (wGEF) perturb kidney tubulogenesis. Dishevelled, which activates both the canonical and non-canonical Wnt/PCP pathway, affect cilia formation in multiciliated cells. In this study, we investigated the role of the noncanoncial Wnt/PCP components Daam1 and ArhGEF19 (wGEF) in renal ciliogenesis utilizing polarized mammalian kidney epithelia cells (MDCKII and IMCD3) and Xenopus laevis embryonic kidney. We demonstrate that knockdown of Daam1 and ArhGEF19 in MDCKII and IMCD3 cells leads to loss of cilia, and Daam1’s effect on ciliogenesis is mediated by the formin-activity of Daam1. Moreover, Daam1 co-localizes with the ciliary transport protein IFT88. Interestingly, knocking down Daam1 in Xenopus kidney does not lead to loss of cilia. This data suggests a new role for Daam1 in the formation of primary cilia.

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Primary cilia formation does not rely on WNT/β-catenin signaling

10.1101/2020.10.30.361642 ◽

2020 ◽

Author(s):

Ondrej Bernatik ◽

Petra Paclikova ◽

Anna Kotrbova ◽

Vitezslav Bryja ◽

Lukas Cajanek

Keyword(s):

Primary Cilia ◽

Wnt Pathway ◽

Inhibitory Effect ◽

Positive Role ◽

Knock Out ◽

Wnt Ligands ◽

Cilia Formation ◽

And Function ◽

Cilium Length

Primary cilia act as crucial regulators of embryo development and tissue homeostasis. They are instrumental for modulation of several signaling pathways, including Hedgehog, WNT, and TGF-β. However gaps exist in our understanding of how cilia formation and function is regulated.Recent work has implicated WNT/β-catenin signaling pathway in the regulation of ciliogenesis, yet the results are conflicting. One model suggests that WNT/β-catenin signaling negatively regulates cilia formation, possibly via effects on cell cycle. In contrast second model proposes a positive role of WNT/β-catenin signaling on cilia formation, mediated by the re-arrangement of centriolar satellites in response to phosphorylation of the key component of WNT/β-catenin pathway, β-catenin.To clarify these discrepancies, we investigated possible regulation of primary cilia by the WNT/β-catenin pathway in cell lines (RPE-1, NIH3T3, HEK293) commonly used to study ciliogenesis. We used WNT3a to activate or LGK974 to block the pathway, and examined initiation of ciliogenesis, cilium length, and percentage of ciliated cells. We show that the treatment by WNT3a has no- or lesser inhibitory effect on cilia formation. Importantly, the inhibition of secretion of endogenous WNT ligands using LGK974 blocks WNT signaling but does not affect ciliogenesis. Finally, using knock-out cells for key WNT pathway components, namely DVL1/2/3, LRP5/6 or AXIN1/2 we show that neither activation nor deactivation of the WNT/β-catenin pathway affects the process of ciliogenesis.These results suggest that WNT/β-catenin-mediated signaling is not generally required for efficient cilia formation. In fact, activation of the WNT/β-catenin pathway in some systems seems to moderately suppress ciliogenesis.

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Protein Kinase A-Mediated Septin7 Phosphorylation Disrupts Septin Filaments and Ciliogenesis

Cells ◽

10.3390/cells10020361 ◽

2021 ◽

Vol 10 (2) ◽

pp. 361

Author(s):

Han-Yu Wang ◽

Chun-Hsiang Lin ◽

Yi-Ru Shen ◽

Ting-Yu Chen ◽

Chia-Yih Wang ◽

...

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Primary Cilia ◽

Cell Growth And Migration ◽

Filament Dynamics ◽

Gtp Binding ◽

Cilia Formation ◽

And Migration ◽

Septin Filament ◽

Kinase A

Septins are GTP-binding proteins that form heteromeric filaments for proper cell growth and migration. Among the septins, septin7 (SEPT7) is an important component of all septin filaments. Here we show that protein kinase A (PKA) phosphorylates SEPT7 at Thr197, thus disrupting septin filament dynamics and ciliogenesis. The Thr197 residue of SEPT7, a PKA phosphorylating site, was conserved among different species. Treatment with cAMP or overexpression of PKA catalytic subunit (PKACA2) induced SEPT7 phosphorylation, followed by disruption of septin filament formation. Constitutive phosphorylation of SEPT7 at Thr197 reduced SEPT7‒SEPT7 interaction, but did not affect SEPT7‒SEPT6‒SEPT2 or SEPT4 interaction. Moreover, we noted that SEPT7 interacted with PKACA2 via its GTP-binding domain. Furthermore, PKA-mediated SEPT7 phosphorylation disrupted primary cilia formation. Thus, our data uncover the novel biological function of SEPT7 phosphorylation in septin filament polymerization and primary cilia formation.

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Centrin2 regulates CP110 removal in primary cilium formation

The Journal of Cell Biology ◽

10.1083/jcb.201411070 ◽

2015 ◽

Vol 208 (6) ◽

pp. 693-701 ◽

Cited By ~ 38

Author(s):

Suzanna L. Prosser ◽

Ciaran G. Morrison

Keyword(s):

Calcium Binding ◽

Primary Cilia ◽

Reverse Genetics ◽

Cell Types ◽

Serum Starvation ◽

Basal Bodies ◽

Cilium Formation ◽

Cellular Quiescence ◽

Retinal Pigmented Epithelial Cells

Primary cilia are antenna-like sensory microtubule structures that extend from basal bodies, plasma membrane–docked mother centrioles. Cellular quiescence potentiates ciliogenesis, but the regulation of basal body formation is not fully understood. We used reverse genetics to test the role of the small calcium-binding protein, centrin2, in ciliogenesis. Primary cilia arise in most cell types but have not been described in lymphocytes. We show here that serum starvation of transformed, cultured B and T cells caused primary ciliogenesis. Efficient ciliogenesis in chicken DT40 B lymphocytes required centrin2. We disrupted CETN2 in human retinal pigmented epithelial cells, and despite having intact centrioles, they were unable to make cilia upon serum starvation, showing abnormal localization of distal appendage proteins and failing to remove the ciliation inhibitor CP110. Knockdown of CP110 rescued ciliation in CETN2-deficient cells. Thus, centrin2 regulates primary ciliogenesis through controlling CP110 levels.

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