scholarly journals ARL3 Mediates BBSome Ciliary Turnover by Promoting Its Outward Diffusion through the Transition Zone

2021 ◽  
Author(s):  
Yan-Xia Liu ◽  
Wei-Yue Sun ◽  
Bin Xue ◽  
Rui-Kai Zhang ◽  
Wen-Juan Li ◽  
...  
Keyword(s):  
Transition Zone ◽  
Phospholipase D ◽  
Physiological Condition ◽  
Intraflagellar Transport ◽  
Outward Diffusion ◽  
Ciliary Membrane ◽  
Downstream Signaling ◽  
Extracellular Stimuli ◽  
Signaling Components ◽  
Ciliary Signaling

Ciliary receptors and their certain downstream signaling components undergo intraflagellar transport (IFT) as BBSome cargoes to maintain their ciliary dynamics for sensing and transducing extracellular stimuli inside the cell. Cargo laden BBSomes shed from retrograde IFT at the proximal ciliary region above the transition zone (TZ) followed by diffusing through the TZ for ciliary retrieval, while how the BBSome barrier passage is controlled remains elusive. Here, we show that the BBSome is a major effector of the Arf-like 3 (ARL3) GTPase in Chlamydomonas. Under physiological condition, ARL3GDP binds the membrane for diffusing into and residing in cilia. Following a nucleotide conversion, ARL3GTP dissociates with the ciliary membrane and binds and recruits the IFT-detached and cargo (phospholipase D, PLD)-laden BBSome at the proximal ciliary region to diffuse through the TZ and out of cilia. ARL3 deficiency impairs ciliary signaling, e.g. phototaxis of Chlamydomonas cells, by disrupting BBSome ciliary retrieval, providing a mechanistic understanding behind BBSome ciliary turnover required for ciliary signaling.

scholarly journals Bardet-Biedl Syndrome 3 protein promotes ciliary exit of the signaling protein phospholipase D via the BBSome

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Yan-Xia Liu ◽  
Bin Xue ◽  
Wei-Yue Sun ◽  
Jenna L Wingfield ◽  
Jun Sun ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Phospholipase D ◽  
Basal Body ◽  
Regulatory Mechanism ◽  
Intraflagellar Transport ◽  
Bound State ◽  
Signaling Proteins ◽  
Bardet Biedl Syndrome ◽  
Signaling Protein ◽  
Ciliary Signaling

Certain ciliary signaling proteins couple with the BBSome, a conserved complex of Bardet-Biedl syndrome (BBS) proteins, to load onto retrograde intraflagellar transport (IFT) trains for their removal out of cilia in Chlamydomonas reinhardtii. Here, we show that loss of the Arf-like 6 (ARL6) GTPase BBS3 causes the signaling protein phospholipase D (PLD) to accumulate in cilia. Upon targeting to the basal body, BBSomes enter and cycle through cilia via IFT, while BBS3 in a GTP-bound state separates from BBSomes, associates with the membrane, and translocates from the basal body to cilia by diffusion. Upon arriving at the ciliary tip, GTP-bound BBS3 binds and recruits BBSomes to the ciliary membrane for interacting with PLD, thus making the PLD-laden BBSomes available to load onto retrograde IFT trains for ciliary exit. Therefore, BBS3 promotes PLD exit from cilia via the BBSome providing a regulatory mechanism for ciliary signaling protein removal out of cilia.

scholarly journals A WDR35-dependent coat protein complex transports ciliary membrane cargo vesicles to cilia

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Tooba Quidwai ◽  
Jiaolong Wang ◽  
Emma A Hall ◽  
Narcis A Petriman ◽  
Weihua Leng ◽  
...  
Keyword(s):  
Coat Protein ◽  
Membrane Proteins ◽  
Sequence Homology ◽  
Protein Complex ◽  
Intraflagellar Transport ◽  
Retrograde Transport ◽  
Ciliary Membrane ◽  
Mouse Mutants ◽  
Core Components

Intraflagellar transport (IFT) is a highly conserved mechanism for motor-driven transport of cargo within cilia, but how this cargo is selectively transported to cilia is unclear. WDR35/IFT121 is a component of the IFT-A complex best known for its role in ciliary retrograde transport. In the absence of WDR35, small mutant cilia form but fail to enrich in diverse classes of ciliary membrane proteins. In Wdr35 mouse mutants, the non-core IFT-A components are degraded and core components accumulate at the ciliary base. We reveal deep sequence homology of WDR35 and other IFT-A subunits to α and ß' COPI coatomer subunits, and demonstrate an accumulation of 'coat-less' vesicles which fail to fuse with Wdr35 mutant cilia. We determine that recombinant non-core IFT-As can bind directly to lipids and provide the first in-situ evidence of a novel coat function for WDR35, likely with other IFT-A proteins, in delivering ciliary membrane cargo necessary for cilia elongation.

scholarly journals Expression of IFT140 During Bone Development

2019 ◽  
Vol 67 (10) ◽  
pp. 723-734
Author(s):  
Chenyang Zhang ◽  
Shuai Zhang ◽  
Yao Sun
Keyword(s):  
Primary Cilia ◽  
Soft Tissues ◽  
Core Protein ◽  
Bone Development ◽  
Mrna Level ◽  
Intraflagellar Transport ◽  
Expression Level ◽  
Cell Functions ◽  
Extracellular Stimuli ◽  
Molecular Signals

Primary cilia, hair-like organelles projecting from the surface of cells, are critical for sensing extracellular stimuli and transmitting molecular signals that regulate cell functions. During bone development, cell cilia are found in several types of cells, but their roles require further investigation. Intraflagellar transport (IFT) is essential for the formation and maintenance of most eukaryotic cilia. IFT140 is a core protein of the IFT-A complex. Mutations in IFT140 have been associated with cases of skeletal ciliopathies. In this study, we examined the expression of IFT140 during bone development. The results showed that, compared with many soft tissues, Ift140 (mRNA level) was highly expressed in bone. Moreover, its expression level was downregulated in the long bones of murine osteoporosis models. At the histological level, IFT140 was characteristically expressed in osteoblasts and chondrocytes at representative stages of bone development, and its expression level in these two types of cells was observed in two waves. These findings suggest that IFT140 may play an important role in the process of chondrogenic and osteogenic differentiation during bone development.

scholarly journals Par3 functions in the biogenesis of the primary cilium in polarized epithelial cells

2007 ◽  
Vol 179 (6) ◽  
pp. 1133-1140 ◽  
Author(s):  
Jeff Sfakianos ◽  
Akashi Togawa ◽  
Sandra Maday ◽  
Mike Hull ◽  
Marc Pypaert ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Primary Cilium ◽  
Basolateral Membrane ◽  
Intraflagellar Transport ◽  
Binding Motif ◽  
Apical Surface ◽  
Anterograde Transport ◽  
Ciliary Membrane ◽  
Microtubule Motor ◽  
Dependent Transport

Par3 is a PDZ protein important for the formation of junctional complexes in epithelial cells. We have identified an additional role for Par3 in membrane biogenesis. Although Par3 was not required for maintaining polarized apical or basolateral membrane domains, at the apical surface, Par3 was absolutely essential for the growth and elongation of the primary cilium. The activity reflected its ability to interact with kinesin-2, the microtubule motor responsible for anterograde transport of intraflagellar transport particles to the tip of the growing cilium. The Par3 binding partners Par6 and atypical protein kinase C interacted with the ciliary membrane component Crumbs3 and we show that the PDZ binding motif of Crumbs3 was necessary for its targeting to the ciliary membrane. Thus, the Par complex likely serves as an adaptor that couples the vectorial movement of at least a subset of membrane proteins to microtubule-dependent transport during ciliogenesis.

scholarly journals Use of the Metallothionein Promoter-Human Growth Hormone-Releasing Hormone (GHRH) Mouse to Identify Regulatory Pathways that Suppress Pituitary Somatotrope Hyperplasia and Adenoma Formation due to GHRH-Receptor Hyperactivation

Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 3177-3185 ◽  
Author(s):  
Raul M. Luque ◽  
Beatriz S. Soares ◽  
Xiao-ding Peng ◽  
Sonia Krishnan ◽  
Jose Cordoba-Chacon ◽  
...  
Keyword(s):  
Cell Cycle Progression ◽  
Human Growth ◽  
Mrna Levels ◽  
Cycle Progression ◽  
Regulatory Pathways ◽  
Downstream Signaling ◽  
Ghrh Receptor ◽  
Metallothionein Promoter ◽  
Hyperplastic Tissue ◽  
Signaling Components

Hyperactivation of the GHRH receptor or downstream signaling components is associated with hyperplasia of the pituitary somatotrope population, in which adenomas form relatively late in life, with less than 100% penetrance. Hyperplastic and adenomatous pituitaries of metallothionein promoter-human GHRH transgenic (Tg) mice (4 and > 10 months, respectively) were used to identify mechanisms that may prevent or delay adenoma formation in the presence of excess GHRH. In hyperplastic pituitaries, expression of the late G1/G2 marker Ki67 increased, whereas the proportion of 5-bromo-2′-deoxyuridine-labeled cells (S phase marker) did not differ from age-matched controls. These results indicate cell cycle progression is blocked, with further evidence suggesting that enhanced p27 activity may contribute to this process. For adenomas, formation was associated with loss of p27 activity (nuclear localization and mRNA). Increased endogenous somatostatin (SST) tone may also slow the conversion from hyperplastic to adenomatous state because mRNA levels for SST receptors, sst2 and sst5, were elevated in hyperplastic pituitaries, whereas adenomas were associated with a decline in sst1 and sst5 mRNA. Also, SST-knockout Tg pituitaries were larger and adenomas formed earlier compared with those of SST-intact Tg mice. Unexpectedly, these changes were independent of changes in proliferation rate within the hyperplastic tissue, suggesting that endogenous SST controls GHRH-induced adenoma formation primarily via modulation of apoptotic and/or cellular senescence pathways, consistent with the predicted function of some of the most differentially expressed genes (Casp1, MAP2K1, TNFR2) identified by membrane arrays and confirmed by quantitative real-time RT-PCR.

scholarly journals Centrioles initiate cilia assembly but are dispensable for maturation and maintenance in C. elegans

2017 ◽  
Vol 216 (6) ◽  
pp. 1659-1671 ◽  
Author(s):  
Daniel Serwas ◽  
Tiffany Y. Su ◽  
Max Roessler ◽  
Shaohe Wang ◽  
Alexander Dammermann
Keyword(s):  
Fluorescence Microscopy ◽  
Transition Zone ◽  
Electron Tomography ◽  
Intraflagellar Transport ◽  
Basal Bodies ◽  
C Elegans ◽  
Cilia Formation ◽  
Syndrome Protein

Cilia are cellular projections that assemble on centriole-derived basal bodies. While cilia assembly is absolutely dependent on centrioles, it is not known to what extent they contribute to downstream events. The nematode C. elegans provides a unique opportunity to address this question, as centrioles do not persist at the base of mature cilia. Using fluorescence microscopy and electron tomography, we find that centrioles degenerate early during ciliogenesis. The transition zone and axoneme are not completely formed at this time, indicating that cilia maturation does not depend on intact centrioles. The hydrolethalus syndrome protein HYLS-1 is the only centriolar protein known to remain at the base of mature cilia and is required for intraflagellar transport trafficking. Surprisingly, targeted degradation of HYLS-1 after initiation of ciliogenesis does not affect ciliary structures. Taken together, our results indicate that while centrioles are essential to initiate cilia formation, they are dispensable for cilia maturation and maintenance.

scholarly journals Intraflagellar Transport Is Required for the Vectorial Movement of TRPV Channels in the Ciliary Membrane

2005 ◽  
Vol 15 (18) ◽  
pp. 1695-1699 ◽  
Author(s):  
Hongmin Qin ◽  
Dylan T. Burnette ◽  
Young-Kyung Bae ◽  
Paul Forscher ◽  
Maureen M. Barr ◽  
...  
Keyword(s):  
Intraflagellar Transport ◽  
Ciliary Membrane ◽  
Trpv Channels

scholarly journals Cyclic AMP Controls mTOR through Regulation of the Dynamic Interaction between Rheb and Phosphodiesterase 4D

2010 ◽  
Vol 30 (22) ◽  
pp. 5406-5420 ◽  
Author(s):  
Hyun Wook Kim ◽  
Sang Hoon Ha ◽  
Mi Nam Lee ◽  
Elaine Huston ◽  
Do-Hyung Kim ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Mammalian Target Of Rapamycin ◽  
Dynamic Interaction ◽  
Negative Regulator ◽  
Camp Phosphodiesterase ◽  
Extracellular Stimuli ◽  
Phosphodiesterase 4D ◽  
Signaling Components ◽  
Camp Levels ◽  
Regulatory Event

ABSTRACT The mammalian target of rapamycin complex 1 (mTORC1) is a molecular hub that regulates protein synthesis in response to a number of extracellular stimuli. Cyclic AMP (cAMP) is considered to be an important second messenger that controls mTOR; however, the signaling components of this pathway have not yet been elucidated. Here, we identify cAMP phosphodiesterase 4D (PDE4D) as a binding partner of Rheb that acts as a cAMP-specific negative regulator of mTORC1. Under basal conditions, PDE4D binds Rheb in a noncatalytic manner that does not require its cAMP-hydrolyzing activity and thereby inhibits the ability of Rheb to activate mTORC1. However, elevated cAMP levels disrupt the interaction of PDE4D with Rheb and increase the interaction between Rheb and mTOR. This enhanced Rheb-mTOR interaction induces the activation of mTORC1 and cap-dependent translation, a cellular function of mTORC1. Taken together, our results suggest a novel regulatory mechanism for mTORC1 in which the cAMP-determined dynamic interaction between Rheb and PDE4D provides a key, unique regulatory event. We also propose a new role for PDE4 as a molecular transducer for cAMP signaling.

scholarly journals Flagella Ca2+ elevations regulate pausing of retrograde intraflagellar transport trains in adherent Chlamydomonas flagella

2020 ◽  
Author(s):  
Cecile Fort ◽  
Peter Collingridge ◽  
Colin Brownlee ◽  
Glen Wheeler
Keyword(s):  
Membrane Proteins ◽  
Green Alga ◽  
High Frequency ◽  
Intraflagellar Transport ◽  
Gliding Motility ◽  
Membrane Glycoproteins ◽  
Ciliary Membrane ◽  
Process Uncertainty ◽  
Temporal Properties ◽  
Transient Interactions

AbstractThe movement of ciliary membrane proteins is directed by transient interactions with intraflagellar transport (IFT) trains. The green alga Chlamydomonas has adapted this process for gliding motility, using IFT to move adhesive glycoproteins (FMG-1B) in the flagella membrane. Although Ca2+ signalling contributes directly to the gliding process, uncertainty remains over the mechanisms through which Ca2+ acts to influence the movement of IFT trains. Here we show that flagella Ca2+ elevations regulate IFT primarily by initiating the movement of paused retrograde IFT trains. Flagella Ca2+ elevations exhibit complex spatial and temporal properties, including high frequency repetitive Ca2+ elevations that prevent the accumulation of paused retrograde IFT trains. We show that flagella Ca2+ elevations disrupt the IFT-dependent movement of microspheres along the flagella membrane. The results suggest that flagella Ca2+ elevations directly disrupt the interaction between retrograde IFT particles and flagella membrane glycoproteins to modulate gliding motility and the adhesion of the flagellum to a surface.

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