scholarly journals Trace Amine-Associated Receptor 1 Localization at the Apical Plasma Membrane Domain of Fisher Rat Thyroid Epithelial Cells Is Confined to Cilia

2015 ◽  
Vol 4 (1) ◽  
pp. 30-41 ◽  
Author(s):  
Joanna Szumska ◽  
Maria Qatato ◽  
Maren Rehders ◽  
Dagmar F�hrer ◽  
Heike Biebermann ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Apical Plasma Membrane ◽  
Membrane Domain ◽  
Trace Amine ◽  
Rat Thyroid ◽  
Plasma Membrane Domain

Selective localization of the polytopic membrane protein prominin in microvilli of epithelial cells - a combination of apical sorting and retention in plasma membrane protrusions

1999 ◽  
Vol 112 (7) ◽  
pp. 1023-1033 ◽  
Author(s):  
D. Corbeil ◽  
K. Roper ◽  
M.J. Hannah ◽  
A. Hellwig ◽  
W.B. Huttner
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Mdck Cells ◽  
Apical Plasma Membrane ◽  
Membrane Domain ◽  
Membrane Protrusions ◽  
Selective Retention ◽  
Polytopic Membrane Protein ◽  
Plasma Membrane Domain

Prominin is a recently identified polytopic membrane protein expressed in various epithelial cells, where it is selectively associated with microvilli. When expressed in non-epithelial cells, prominin is enriched in plasma membrane protrusions. This raises the question of whether the selective association of prominin with microvilli in epithelial cells is solely due to its preference for, and stabilization in, plasma membrane protrusions, or is due to both sorting to the apical plasma membrane domain and subsequent enrichment in plasma membrane protrusions. To investigate this question, we have generated stably transfected MDCK cells expressing either full-length or C-terminally truncated forms of mouse prominin. Confocal immunofluorescence and domain-selective cell surface biotinylation experiments on transfected MDCK cells grown on permeable supports demonstrated the virtually exclusive apical localization of prominin at steady state. Pulse-chase experiments in combination with domain-selective cell surface biotinylation showed that newly synthesized prominin was directly targeted to the apical plasma membrane domain. Immunoelectron microscopy revealed that prominin was confined to microvilli rather than the planar region of the apical plasma membrane. Truncation of the cytoplasmic C-terminal tail of prominin impaired neither its apical cell surface expression nor its selective retention in microvilli. Both the apical-specific localization of prominin and its selective retention in microvilli were maintained when MDCK cells were cultured in low-calcium medium, i.e. in the absence of tight junctions. Taken together, our results show that: (i) prominin contains dual targeting information, for direct delivery to the apical plasma membrane domain and for the enrichment in the microvillar subdomain; and (ii) this dual targeting does not require the cytoplasmic C-terminal tail of prominin and still occurs in the absence of tight junctions. The latter observation suggests that entry into, and retention in, plasma membrane protrusions may play an important role in the establishment and maintenance of the apical-basal polarity of epithelial cells.

scholarly journals Expression, Distribution, and Activity of Na+,K+-ATPase in Normal and Cholestatic Rat Liver

1998 ◽  
Vol 46 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Lukas Landmann ◽  
Sabine Angermüller ◽  
Christoph Rahner ◽  
Bruno Stieger
Keyword(s):  
Enzyme Activity ◽  
Plasma Membrane ◽  
Driving Force ◽  
Bile Secretion ◽  
Transport Systems ◽  
Apical Plasma Membrane ◽  
Membrane Domain ◽  
Expression Domain ◽  
Duct Ligation ◽  
Plasma Membrane Domain

Hepatocellular Na+,K+-ATPase is an important driving force for bile secretion and has been localized to the basolateral plasma membrane domain. Cholestasis or impaired bile flow is known to modulate the expression, domain specificity, and activity of various transport systems involved in bile secretion. This study examined Na+,K+-ATPase after ethinylestradiol (EE) treatment and after bile duct ligation (BDL), two rat models of cholestasis. It applied quantitative immunoblotting, biochemical and cytochemical determination of enzyme activity, and immunocytochemistry to the same livers. The data showed a good correlation among the results of the different methods. Neither EE nor BDL induced alterations in the subcellular distribution of Na+,K+-ATPase, which was found in the basolateral but not in the canalicular (apical) plasma membrane domain. Protein expression and enzyme activity showed a small (~10%) decrease after EE treatment and a similar increase after BDL. These modest changes could not be detected by immunofluorescence, immuno EM, or cytochemistry. The data, therefore, demonstrate that Na+,K+-ATPase is only slightly affected by EE and BDL. They suggest that other components of the bile secretory apparatus that take effect downstream of the primary basolateral driving force may play a more prominent role in the pathogenesis of cholestasis.

Distribution of sodium transporters and aquaporin-1 in the human choroid plexus

2006 ◽  
Vol 291 (1) ◽  
pp. C59-C67 ◽  
Author(s):  
Jeppe Praetorius ◽  
Søren Nielsen
Keyword(s):  
Plasma Membrane ◽  
Choroid Plexus ◽  
Water Channel ◽  
Apical Plasma Membrane ◽  
Membrane Domain ◽  
Choroid Plexus Epithelium ◽  
Human Choroid Plexus ◽  
Fluid Production ◽  
Species Pattern ◽  
Plasma Membrane Domain

The choroid plexus epithelium secretes electrolytes and fluid in the brain ventricular lumen at high rates. Several channels and ion carriers have been identified as likely mediators of this transport in rodent choroid plexus. This study aimed to map several of these proteins to the human choroid plexus. Immunoperoxidase-histochemistry was employed to determine the cellular and subcellular localization of the proteins. The water channel, aquaporin (AQP) 1, was predominantly situated in the apical plasma membrane domain, although distinct basolateral and endothelial immunoreactivity was also observed. The Na+-K+-ATPase α1-subunit was exclusively localized apically in the human choroid plexus epithelial cells. Immunoreactivity for the Na+-K+-2Cl− cotransporter, NKCC1, was likewise confined to the apical plasma membrane domain of the epithelium. The Cl−/HCO3− exchanger, AE2, was localized basolaterally, as was the Na+-dependent Cl−/HCO3− exchanger, NCBE, and the electroneutral Na+-HCO3− cotransporter, NBCn1. No immunoreactivity was found toward the Na+-dependent acid/base transporters NHE1 or NBCe2. Hence, the human choroid plexus epithelium displays an almost identical distribution pattern of water channels and Na+ transporters as the rat and mouse choroid plexus. This general cross species pattern suggests central roles for these transporters in choroid plexus functions such as cerebrospinal fluid production.

scholarly journals Interaction with mLin-7 Alters the Targeting of Endocytosed Transmembrane Proteins in Mammalian Epithelial Cells

2001 ◽  
Vol 12 (5) ◽  
pp. 1329-1340 ◽  
Author(s):  
Samuel W. Straight ◽  
Liguang Chen ◽  
David Karnak ◽  
Ben Margolis
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Protein Targeting ◽  
Mdck Cells ◽  
Pdz Domain ◽  
Receptor Protein ◽  
Membrane Domain ◽  
Basolateral Plasma Membrane ◽  
Carboxyl Terminal ◽  
Plasma Membrane Domain

To investigate the targeting mechanism for proteins bound to the mammalian Lin-7 (mLin-7) PDZ domain, we created receptor protein chimeras composed of the carboxyl-terminal amino acids of LET-23 fused to truncated nerve growth factor receptor/P75. mLin-7 bound to the chimera with a wild-type LET-23 carboxyl-terminal tail (P75t-Let23WT), but not a mutant tail (P75t-Let23MUT). In Madin-Darby canine kidney (MDCK) cells, P75t-Let23WT localized to the basolateral plasma membrane domain, whereas P75t-Let23MUT remained apical. Furthermore, mutant mLin-7 constructs acted as dominant interfering proteins and inhibited the basolateral localization of P75t-Let23WT. The mechanisms for this differential localization were examined further, and, initially, we found that P75t-Let23WT and P75t-Let23MUT were delivered equally to the apical and basolateral plasma membrane domains. Although basolateral retention of P75t-Let23WT, but not P75t-Let23MUT, was observed, the greatest difference in receptor localization was seen in the rapid trafficking of P75t-Let23WT to the basolateral plasma membrane domain after endocytosis, whereas P75t-Let23MUT was degraded in lysosomes, indicating that mLin-7 binding can alter the fate of endocytosed proteins. Altogether, these data support a model for basolateral protein targeting in mammalian epithelial cells dependent on protein–protein interactions with mLin-7, and also suggest a dynamic role for mLin-7 in endosomal sorting.

scholarly journals Segregation of Glucosylceramide and Sphingomyelin Occurs in the Apical to Basolateral Transcytotic Route in HepG2 Cells

1997 ◽  
Vol 137 (2) ◽  
pp. 347-357 ◽  
Author(s):  
Sven C.D. van IJzendoorn ◽  
Mirjam M.P. Zegers ◽  
Jan Willem Kok ◽  
Dick Hoekstra
Keyword(s):  
Plasma Membrane ◽  
Hepg2 Cells ◽  
Accurate Estimation ◽  
Apical Plasma Membrane ◽  
Membrane Domain ◽  
Dibutyryl Camp ◽  
Preferential Localization ◽  
Basolateral Plasma Membrane ◽  
Plasma Membrane Domain ◽  
Fluorescent Lipid

HepG2 cells are highly differentiated hepatoma cells that have retained an apical, bile canalicular (BC) plasma membrane polarity. We investigated the dynamics of two BC-associated sphingolipids, glucosylceramide (GlcCer) and sphingomyelin (SM). For this, the cells were labeled with fluorescent acyl chainlabeled 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)- amino]hexanoic acid (C6-NBD) derivatives of either GlcCer (C6-NBD-GlcCer) or SM (C6-NBD-SM). The pool of the fluorescent lipid analogues present in the basolateral plasma membrane domain was subsequently depleted and the apically located C6-NBD-lipid was chased at 37°C. By using fluorescence microscopical analysis and a new assay that allows an accurate estimation of the fluorescent lipid pool in the apical membrane, qualitative and quantitative insight was obtained concerning kinetics, extent and (intra)cellular sites of the redistribution of apically located C6-NBD-GlcCer and C6-NBD-SM. It is demonstrated that both lipids display a preferential localization, C6-NBD-GlcCer in the apical and C6-NBD-SM in the basolateral area. Such a preference is expressed during transcytosis of both sphingolipids from the apical to the basolateral plasma membrane domain, a novel lipid trafficking route in HepG2 cells. Whereas the vast majority of the apically derived C6-NBD-SM was rapidly transcytosed to the basolateral surface, most of the apically internalized C6-NBD-GlcCer was efficiently redirected to the BC. The redirection of C6-NBD-GlcCer did not involve trafficking via the Golgi apparatus. Evidence is provided which suggests the involvement of vesicular compartments, located subjacent to the apical plasma membrane. Interestingly, the observed difference in preferential localization of C6-NBD-GlcCer and C6NBD-SM was perturbed by treatment of the cells with dibutyryl cAMP, a stable cAMP analogue. While the preferential apical localization of C6-NBD-GlcCer was amplified, dibutyryl cAMP-treatment caused apically retrieved C6-NBD-SM to be processed via a similar pathway as that of C6-NBD-GlcCer. The data unambiguously demonstrate that segregation of GlcCer and SM occurs in the reverse transcytotic route, i.e., during apical to basolateral transport, which results in the preferential localization of GlcCer and SM in the apical and basolateral region of the cells, respectively. A role for non-Golgi–related, sub-apical vesicular compartments in the sorting of GlcCer and SM is proposed.

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