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 ◽  
...  

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.

2015 ◽  
Vol 211 (2) ◽  
pp. 287-294 ◽  
Author(s):  
Emily H. Stoops ◽  
Michael Hull ◽  
Christina Olesen ◽  
Kavita Mistry ◽  
Jennifer L. Harder ◽  
...  

In polarized epithelial cells, newly synthesized cell surface proteins travel in carrier vesicles from the trans Golgi network to the apical or basolateral plasma membrane. Despite extensive research on polarized trafficking, the sites of protein delivery are not fully characterized. Here we use the SNAP tag system to examine the site of delivery of the apical glycoprotein gp135. We show that a cohort of gp135 is delivered to a ring surrounding the base of the primary cilium, followed by microtubule-dependent radial movement away from the cilium. Delivery to the periciliary ring was specific to newly synthesized and not recycling protein. A subset of this newly delivered protein traverses the basolateral membrane en route to the apical membrane. Crumbs3a, another apical protein, was not delivered to the periciliary region, instead making its initial apical appearance in a pattern that resembled its steady-state distribution. Our results demonstrate a surprising “hot spot” for gp135 protein delivery at the base of the primary cilium and suggest the existence of a novel microtubule-based directed movement of a subset of apical surface proteins.


2019 ◽  
Author(s):  
Miguel Bernabé-Rubio ◽  
Minerva Bosch-Fortea ◽  
Esther García ◽  
Jorge Bernardino de la Serna ◽  
Miguel A. Alonso

AbstractThe primary cilium is a specialized plasma membrane protrusion that harbors receptors involved in important signaling pathways. Despite its central role in regulating cellular behavior, the biogenesis of the primary cilium is not fully understood. In fact, the source of the ciliary membrane remains a mystery in cell types that assemble their primary cilium entirely at the cell surface, such as polarized renal epithelial cells. After cytokinesis, the remnant of the midbody of these cells moves to the center of the apical surface, where it licenses the centrosome for ciliogenesis through an unidentified mechanism. Here, to investigate the origin of the ciliary membrane and the role of the midbody remnant, we analyzed membrane compaction and lipid dynamics at the microscale and nanoscale in living renal epithelial MDCK cells. We found that a specialized patch made of condensed membranes with restricted lipid lateral mobility surrounds the midbody remnant. This patch accompanies the remnant on its journey towards the centrosome and, once the two structures have met, the remnant delivers part of membranes of the patch to build the ciliary membrane. In this way, we have determined the origin of the ciliary membrane and the contribution of the midbody remnant to primary cilium formation in cells whose primary cilium is assembled at the plasma membrane.


2021 ◽  
Author(s):  
Miguel Bernabé-Rubio ◽  
Minerva Bosch-Fortea ◽  
Miguel A. Alonso ◽  
Jorge Bernardino de la Serna

AbstractThe primary cilium is a specialized plasma membrane protrusion with important receptors for signalling pathways. In polarized epithelial cells, the primary cilium assembles after the midbody remnant (MBR) encounters the centrosome at the apical surface. The membrane surrounding the MBR, namely remnant associated membrane patch (RAMP) once situated next to the centrosome, releases some of its lipid components to form a centrosome-associated membrane patch (CAMP) from which the ciliary membrane stems. The RAMP undergoes a spatiotemporal membrane refinement during the formation of the CAMP, which becomes highly enriched in condensed membranes with low lateral mobility. To better understand this process, we have developed a correlative imaging approach that yields quantitative information about the lipid lateral packing, its mobility and collective assembly at the plasma membrane at different spatial scales over time. Our work paves the way towards a quantitative understanding of lipid collective assembly at the plasma membrane spatiotemporally as a functional determinant in cell biology and its direct correlation with the membrane physicochemical state. These findings allowed us to gain a deeper insight into the mechanisms behind the biogenesis of the ciliary membrane of polarized epithelial cells.


1995 ◽  
Vol 108 (1) ◽  
pp. 369-377 ◽  
Author(s):  
K.L. Soole ◽  
M.A. Jepson ◽  
G.P. Hazlewood ◽  
H.J. Gilbert ◽  
B.H. Hirst

To evaluate whether a glycosylphosphatidylinositol (GPI) anchor can function as a protein sorting signal in polarized intestinal epithelial cells, the GPI-attachment sequence from Thy-1 was fused to bacterial endoglucanase E' (EGE') from Clostridium thermocellum and polarity of secretion of the chimeric EGE'-GPI protein was evaluated. The chimeric EGE'-GPI protein was shown to be associated with a GPI anchor by TX-114 phase-partitioning and susceptibility to phosphoinositol-specific phospholipase C. In polarized MDCK cells, EGE' was localized almost exclusively to the apical cell surface, while in polarized intestinal Caco-2 cells, although 80% of the extracellular form of the enzyme was routed through the apical membrane over a 24 hour period, EGE' was also detected at the basolateral membrane. Rates of delivery of EGE'-GPI to the two membrane domains in Caco-2 cells, as determined with a biotinylation protocol, revealed apical delivery was approximately 2.5 times that of basolateral. EGE' delivered to the basolateral cell surface was transcytosed to the apical surface. These data indicate that a GPI anchor does represent a dominant apical sorting signal in intestinal epithelial cells. However, the mis-sorting of a proportion of EGE'GPI to the basolateral surface of Caco-2 cells provides an explanation for additional sorting signals in the ectodomain of some endogenous GPI-anchored proteins.


1998 ◽  
Vol 111 (9) ◽  
pp. 1197-1206
Author(s):  
T. Su ◽  
K.K. Stanley

We have transfected a polarised endothelial cell line, ECV 304, and an epithelial cell line, MDCK, with a well characterised epithelial protein, the rat polymeric immunoglobulin receptor (pIgR), in order to study the protein sorting and transcytosis in endothelial cells. The expressed protein was normally processed and the steady state distribution between apical and basolateral surfaces was similar in both cell types. MDCK cells, however, showed a marked polarity in the delivery of newly synthesised pIgR to the cell surface, and in the release of secretory component. 88% of newly synthesised pIgR in MDCK cells was first delivered to the basolateral surface and 99% of secretory component was released from the apical surface. In contrast the basolateral targeting signal of pIgR was only partially recognised in endothelial cells, with 63% of the newly synthesised pIgR being first delivered to the basolateral surface. At steady state only 43% of the pIgR was found on the basolateral membrane. The direction of dimeric IgA transcytosis in endothelial cells was from apical to basolateral surfaces, opposite to that in MDCK cells. These data suggest that endothelial cells poorly recognise the targeting signals of proteins from epithelial cells, and that the direction of transcytosis is linked to the biological role of the cells.


2009 ◽  
Vol 184 (5) ◽  
pp. 721-736 ◽  
Author(s):  
Ruth Rollason ◽  
Viktor Korolchuk ◽  
Clare Hamilton ◽  
Mark Jepson ◽  
George Banting

CD317/tetherin is a lipid raft–associated integral membrane protein with a novel topology. It has a short N-terminal cytosolic domain, a conventional transmembrane domain, and a C-terminal glycosyl-phosphatidylinositol anchor. We now show that CD317 is expressed at the apical surface of polarized epithelial cells, where it interacts indirectly with the underlying actin cytoskeleton. CD317 is linked to the apical actin network via the proteins RICH2, EBP50, and ezrin. Knocking down expression of either CD317 or RICH2 gives rise to the same phenotype: a loss of the apical actin network with concomitant loss of apical microvilli, an increase in actin bundles at the basal surface, and a reduction in cell height without any loss of tight junctions, transepithelial resistance, or the polarized targeting of apical and basolateral membrane proteins. Thus, CD317 provides a physical link between lipid rafts and the apical actin network in polarized epithelial cells and is crucial for the maintenance of microvilli in such cells.


1997 ◽  
Vol 273 (6) ◽  
pp. C1995-C2001 ◽  
Author(s):  
Stanley D. Hillyard ◽  
Horacio F. Cantiello ◽  
Willy Van Driessche

Skin from larval bullfrogs was mounted in an Ussing-type chamber in which the apical surface was bathed with a Ringer solution containing 115 mM K+ and the basolateral surface was bathed with a Ringer solution containing 115 mM Na+. Ion transport was measured as the short-circuit current ( I sc) with a low-noise voltage clamp, and skin resistance ( R m) was measured by applying a direct current voltage pulse. Membrane impedance was calculated by applying a voltage signal consisting of 53 sine waves to the command stage of the voltage clamp. From the ratio of the Fourier-transformed voltage and current signals, it was possible to calculate the resistance and capacitance of the apical and basolateral membranes of the epithelium ( R a and R b, C a and C b, respectively). With [Formula: see text] as the anion, R m decreased rapidly within 5 min following the addition of 150 U/ml nystatin to the apical solution, whereas I sc increased from 0.66 to 52.03 μA/cm2 over a 60-min period. These results indicate that nystatin becomes rapidly incorporated into the apical membrane and that the increase in basolateral K+ permeability requires a more prolonged time course. Intermediate levels of I sc were obtained by adding 50, 100, and 150 U/ml nystatin to the apical solution. This produced a progressive decrease in R a and R b while C a and C b remained constant. With Cl− as the anion, I sc values increased from 2.03 to 89.57 μA/cm2 following treatment with 150 U/ml nystatin, whereas with gluconate as the anion I sc was only increased from 0.63 to 11.64 μA/cm2. This suggests that the increase in basolateral K+permeability produced by nystatin treatment, in the presence of more permeable anions, is due to swelling of the epithelial cells of the tissue rather than the gradient for apical K+ entry. Finally, C b was not different among skins exposed to Cl−,[Formula: see text], or gluconate, despite the large differences in I sc, nor did inhibition of I scby treatment with hyperosmotic dextrose cause significant changes in C b. These results support the hypothesis that increases in cell volume activate K+ channels that are already present in the basolateral membrane of epithelial cells.


2018 ◽  
Vol 115 (5) ◽  
pp. E934-E943 ◽  
Author(s):  
Peiwei Liu ◽  
Karl F. Lechtreck

Bardet–Biedl syndrome (BBS) is a ciliopathy resulting from defects in the BBSome, a conserved protein complex. BBSome mutations affect ciliary membrane composition, impairing cilia-based signaling. The mechanism by which the BBSome regulates ciliary membrane content remains unknown. Chlamydomonas bbs mutants lack phototaxis and accumulate phospholipase D (PLD) in the ciliary membrane. Single particle imaging revealed that PLD comigrates with BBS4 by intraflagellar transport (IFT) while IFT of PLD is abolished in bbs mutants. BBSome deficiency did not alter the rate of PLD entry into cilia. Membrane association and the N-terminal 58 residues of PLD are sufficient and necessary for BBSome-dependent transport and ciliary export. The replacement of PLD’s ciliary export sequence (CES) caused PLD to accumulate in cilia of cells with intact BBSomes and IFT. The buildup of PLD inside cilia impaired phototaxis, revealing that PLD is a negative regulator of phototactic behavior. We conclude that the BBSome is a cargo adapter ensuring ciliary export of PLD on IFT trains to regulate phototaxis.


2000 ◽  
Vol 74 (13) ◽  
pp. 6050-6057 ◽  
Author(s):  
Raymond J. Pickles ◽  
Jill A. Fahrner ◽  
JenniElizabeth M. Petrella ◽  
Richard C. Boucher ◽  
Jeffrey M. Bergelson

ABSTRACT Lumenal delivery of adenovirus vectors (AdV) results in inefficient gene transfer to human airway epithelium. The human coxsackievirus and adenovirus receptor (hCAR) was detected by immunofluorescence selectively at the basolateral surfaces of freshly excised human airway epithelial cells, suggesting that the absence of apical hCAR constitutes a barrier to adenovirus-mediated gene delivery in vivo. In transfected polarized Madin-Darby canine kidney cells, wild-type hCAR was expressed selectively at the basolateral membrane, whereas hCAR lacking the transmembrane and/or cytoplasmic domains was expressed on both the basolateral and apical membranes. Cells expressing apical hCAR still were not efficiently transduced by AdV applied to the apical surface. However, after the cells were treated with agents that remove components of the apical surface glycocalyx, AdV transduction occurred. These results indicate that adenovirus can infect via receptors located at the apical cell membrane but that the glycocalyx impedes interaction of AdV with apical receptors.


2003 ◽  
Vol 284 (5) ◽  
pp. L689-L700 ◽  
Author(s):  
Scott M. O'Grady ◽  
So Yeong Lee

Electrolyte transport across the adult alveolar epithelium plays an important role in maintaining a thin fluid layer along the apical surface of the alveolus that facilitates gas exchange across the epithelium. Most of the work published on the transport properties of alveolar epithelial cells has focused on the mechanisms and regulation of Na+ transport and, in particular, the role of amiloride-sensitive Na+ channels in the apical membrane and the Na+-K+-ATPase located in the basolateral membrane. Less is known about the identity and role of Cl− and K+ channels in alveolar epithelial cells, but studies are revealing important functions for these channels in regulation of alveolar fluid volume and ionic composition. The purpose of this review is to examine previous work published on Cl− and K+ channels in alveolar epithelial cells and to discuss the conclusions and speculations regarding their role in alveolar cell transport function.


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