scholarly journals Mechanisms and functional features of polarized membrane traffic in epithelial and hepatic cells

1998 ◽  
Vol 336 (2) ◽  
pp. 257-269 ◽  
Author(s):  
Mirjam M. P. ZEGERS ◽  
Dick HOEKSTRA
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Transport Processes ◽  
Protein Kinase Activity ◽  
Transport Pathway ◽  
Hepatic Cells ◽  
Functional Features ◽  
Specific Lipid

Epithelial cells express plasma-membrane polarity in order to meet functional requirements that are imposed by their interaction with different extracellular environments. Thus apical and basolateral membrane domains are distinguished that are separated by tight junctions in order to maintain the specific lipid and protein composition of each domain. In hepatic cells, the plasma membrane is also polarized, containing a sinusoidal (basolateral) and a bile canalicular (apical)-membrane domain. Relevant to the biogenesis of these domains are issues concerning sorting, (co-)transport and regulation of transport of domain-specific membrane components. In epithelial cells, specific proteins and lipids, destined for the apical membrane, are sorted in the trans-Golgi network (TGN), which involves their sequestration into cholesterol/sphingolipid ‘rafts ’, followed by ‘direct ’ transport to the apical membrane. In hepatic cells, a direct apical transport pathway also exists, as revealed by transport of sphingolipids from TGN to the apical membrane. This is remarkable, since in these cells numerous apical membrane proteins are ‘indirectly ’ sorted, i.e. they are first transferred to the basolateral membrane prior to their subsequent transcytosis to the apical membrane. This raises intriguing questions as to the existence of specific lipid rafts in hepatocytes. As demonstrated in studies with HepG2 cells, it has become evident that, in hepatic cells, apical transport pathways can be regulated by protein kinase activity, which in turn modulates cell polarity. Finally, an important physiological function of hepatic cells is their involvement in intracellular transport and secretion of bile-specific lipids. Mechanisms of these transport processes, including the role of multidrug-resistant proteins in lipid translocation, will be discussed in the context of intracellular vesicular transport. Taken together, hepatic cell systems provide an important asset to studies aimed at elucidating mechanisms of sorting and trafficking of lipids (and proteins) in polarized cells in general.

scholarly journals Apiconuclear Organization of Microtubules Does Not Specify Protein Delivery from the Trans-Golgi Network to Different Membrane Domains in Polarized Epithelial Cells

1998 ◽  
Vol 9 (3) ◽  
pp. 685-699 ◽  
Author(s):  
Kent K. Grindstaff ◽  
Robert L. Bacallao ◽  
W. James Nelson
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Golgi Complex ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Membrane Domains ◽  
Trans Golgi Network ◽  
G Cells ◽  
Polarized Epithelial Cells ◽  
Golgi Network

In nonpolarized epithelial cells, microtubules originate from a broad perinuclear region coincident with the distribution of the Golgi complex and extend outward to the cell periphery (perinuclear [PN] organization). During development of epithelial cell polarity, microtubules reorganize to form long cortical filaments parallel to the lateral membrane, a meshwork of randomly oriented short filaments beneath the apical membrane, and short filaments at the base of the cell; the Golgi becomes localized above the nucleus in the subapical membrane cytoplasm (apiconuclear [AN] organization). The AN-type organization of microtubules is thought to be specialized in polarized epithelial cells to facilitate vesicle trafficking between the trans-Golgi Network (TGN) and the plasma membrane. We describe two clones of MDCK cells, which have different microtubule distributions: clone II/G cells, which gradually reorganize a PN-type distribution of microtubules and the Golgi complex to an AN-type during development of polarity, and clone II/J cells which maintain a PN-type organization. Both cell clones, however, exhibit identical steady-state polarity of apical and basolateral proteins. During development of cell surface polarity, both clones rapidly establish direct targeting pathways for newly synthesized gp80 and gp135/170, and E-cadherin between the TGN and apical and basolateral membrane, respectively; this occurs before development of the AN-type microtubule/Golgi organization in clone II/G cells. Exposure of both clone II/G and II/J cells to low temperature and nocodazole disrupts >99% of microtubules, resulting in: 1) 25–50% decrease in delivery of newly synthesized gp135/170 and E-cadherin to the apical and basolateral membrane, respectively, in both clone II/G and II/J cells, but with little or no missorting to the opposite membrane domain during all stages of polarity development; 2) ∼40% decrease in delivery of newly synthesized gp80 to the apical membrane with significant missorting to the basolateral membrane in newly established cultures of clone II/G and II/J cells; and 3) variable and nonspecific delivery of newly synthesized gp80 to both membrane domains in fully polarized cultures. These results define several classes of proteins that differ in their dependence on intact microtubules for efficient and specific targeting between the Golgi and plasma membrane domains.

scholarly journals Putative linear motifs mediate the trafficking to apical and basolateral membranes

2020 ◽  
Author(s):  
Laszlo Dobson ◽  
András Zeke ◽  
Levente Szekeres ◽  
Tamás Langó ◽  
Gábor Tusnády
Keyword(s):  
Epithelial Cells ◽  
Drug Transport ◽  
Basolateral Membrane ◽  
Transmembrane Proteins ◽  
Transport Processes ◽  
Membrane Domains ◽  
Protein Distribution ◽  
Basolateral Membranes ◽  
Linear Motifs ◽  
Cellular Components

AbstractCell polarity refers to the asymmetric organisation of cellular components in various cells. Epithelial cells are the best known examples of polarized cells, featuring apical and basolateral membrane domains. Despite huge efforts, the exact rules governing the protein distribution in such domains are still elusive. In this study we examined linear motifs accumulating in these parts and based on the results we prepared ‘Classical’ and Convolutional Neural Networks to classify human transmembrane proteins localizing into apical/basolateral membranes. Asymmetric expression of drug transporters results in vectorial drug transport, governing the pharmacokinetics of numerous substances, yet the data on how proteins are sorted in epithelial cells is very scattered. The provided dataset may offer help to experimentalists to characterize novel molecular targets to regulate transport processes more precisely.

scholarly journals Sorting of Marburg Virus Surface Protein and Virus Release Take Place at Opposite Surfaces of Infected Polarized Epithelial Cells

2001 ◽  
Vol 75 (3) ◽  
pp. 1274-1283 ◽  
Author(s):  
Christian Sänger ◽  
Elke Mühlberger ◽  
Elena Ryabchikova ◽  
Larissa Kolesnikova ◽  
Hans-Dieter Klenk ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Surface Protein ◽  
Hemorrhagic Fever ◽  
Marburg Virus ◽  
Virus Surface ◽  
Mdckii Cells ◽  
Vesicular Stomatitis ◽  
Polarized Epithelial Cells

ABSTRACT Marburg virus, a filovirus, causes severe hemorrhagic fever with hitherto poorly understood molecular pathogenesis. We have investigated here the vectorial transport of the surface protein GP of Marburg virus in polarized epithelial cells. To this end, we established an MDCKII cell line that was able to express GP permanently (MDCK-GP). The functional integrity of GP expressed in these cells was analyzed using vesicular stomatitis virus pseudotypes. Further experiments revealed that GP is transported in MDCK-GP cells mainly to the apical membrane and is released exclusively into the culture medium facing the apical membrane. When MDCKII cells were infected with Marburg virus, the majority of GP was also transported to the apical membrane, suggesting that the protein contains an autonomous apical transport signal. Release of infectious progeny virions, however, took place exclusively at the basolateral membrane of the cells. Thus, vectorial budding of Marburg virus is presumably determined by factors other than the surface protein.

Coupled NaCl entry into Necturus gallbladder epithelial cells

1982 ◽  
Vol 243 (3) ◽  
pp. C140-C145 ◽  
Author(s):  
A. C. Ericson ◽  
K. R. Spring
Keyword(s):  
Epithelial Cells ◽  
Cell Volume ◽  
Apical Membrane ◽  
Ionic Composition ◽  
Basolateral Membrane ◽  
Cell Swelling ◽  
Disulfonic Acid ◽  
Bathing Solution ◽  
Parallel Operation ◽  
Solute Content

NaCl entry into Necturus maculosus gallbladder epithelial cells was studied by determination of the rate of fluid movement into the cell when the Na+-K+-ATPase was inhibited by 10(-4) M ouabain in the serosal bathing solution. The cell swelling was due to continuing entrance of NaCl into the cell across the apical membrane, which increased the solute content of the cell; the resultant rise in cell osmolality induced water flow and cell swelling. The rate of swelling was 4.3% of the cell volume per minute, equivalent to a volume flow across the apical membrane of 1.44 x 10(-6) cm/s, similar in magnitude to the normal rate of fluid absorption by the gallbladder. We determined the mechanism of NaCl entry by varying the ionic composition of the mucosal bath; when most of the mucosal Na+ or Cl- was replaced, cell volume did not increase during pump inhibition. The rate of NaCl entry was a saturable function of Na+ or Cl- in the mucosal bathing solution with K1/2 values of 26.6 mM for Na+ and 19.5 mM for Cl-. The mode of NaCl entry was probably not the parallel operation of Na+-H+ and Cl(-)-HCO-3 exchangers because of the lack of effect of bicarbonate removal or of the inhibitors amiloride and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid. NaCl entry was reversibly inhibited by bumetanide in the mucosal bathing solution. Transepithelial NaCl and water absorption is the result of the coupled, carrier-mediated movement of NaCl into the cell across the apical membrane and the active extrusion of Na+ by the Na+-K+-ATPase in the basolateral membrane.

scholarly journals The carboxyl-terminally truncated kidney anion exchanger 1 R901X dRTA mutant is unstable at the plasma membrane

2016 ◽  
Vol 310 (9) ◽  
pp. C764-C772 ◽  
Author(s):  
Ensaf Almomani ◽  
Rawad Lashhab ◽  
R. Todd Alexander ◽  
Emmanuelle Cordat
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Anion Exchanger ◽  
Basolateral Membrane ◽  
Recycling Rate ◽  
Wild Type ◽  
Anion Exchanger 1 ◽  
Renal Epithelial Cells ◽  
Gene Coding ◽  
Renal Tubular

Mutations in the SLC4A1 gene coding for kidney anion exchanger 1 (kAE1) cause distal renal tubular acidosis (dRTA). We investigated the fate of the most common truncated dominant dRTA mutant kAE1 R901X. In renal epithelial cells, we found that kAE1 R901X is less abundant than kAE1 wild-type (WT) at the plasma membrane. Although kAE1 WT and kAE1 R901X have similar half-lives, the decreased abundance of kAE1 R901X at the surface is due to an increased endocytosis rate and a decreased recycling rate of endocytosed proteins. We propose that, in polarized renal epithelial cells, the apically mistargeted kAE1 R901X mutant is endocytosed faster than kAE1 WT and its recycling to the basolateral membrane is delayed. This resets the equilibrium, such that kAE1 R901X resides predominantly in an endomembrane compartment, thereby likely participating in development of dRTA disease.

Selective permeability barrier to urea in shark rectal gland

2005 ◽  
Vol 289 (1) ◽  
pp. F83-F89 ◽  
Author(s):  
Joshua D. Zeidel ◽  
John C. Mathai ◽  
John D. Campbell ◽  
Wily G. Ruiz ◽  
Gerard L. Apodaca ◽  
...  
Keyword(s):  
Activation Energy ◽  
Epithelial Cells ◽  
Water Flow ◽  
Water Permeability ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Water Flux ◽  
Rectal Gland ◽  
Basolateral Membranes ◽  
Urea Permeability

Elasmobranchs such as the dogfish shark Squalus acanthius achieve osmotic homeostasis by maintaining urea concentrations in the 300- to 400-mM range, thus offsetting to some degree ambient marine osmolalities of 900–1,000 mosmol/kgH2O. These creatures also maintain salt balance without losing urea by secreting a NaCl-rich (500 mM) and urea-poor (18 mM) fluid from the rectal gland that is isotonic with the plasma. The composition of the rectal gland fluid suggests that its epithelial cells are permeable to water and not to urea. Because previous work showed that lipid bilayers that permit water flux do not block flux of urea, we reasoned that the plasma membranes of rectal gland epithelial cells must either have aquaporin water channels or must have some selective barrier to urea flux. We therefore isolated apical and basolateral membranes from shark rectal glands and determined their permeabilities to water and urea. Apical membrane fractions were markedly enriched for Na-K-2Cl cotransporter, whereas basolateral membrane fractions were enriched for Na-K-ATPase. Basolateral membrane osmotic water permeability (Pf) averaged 4.3 ± 1.3 × 10−3 cm/s, whereas urea permeability averaged 4.2 ± 0.8 × 10−7 cm/s. The activation energy for water flow averaged 16.4 kcal/mol. Apical membrane Pf averaged 7.5 ± 1.6 × 10−4 cm/s, and urea permeability averaged 2.2 ± 0.4 × 10−7 cm/s, with an average activation energy for water flow of 18.6 kcal/mol. The relatively low water permeabilities and high activation energies argue strongly against water flux via aquaporins. Comparison of membrane water and urea permeabilities with those of artificial liposomes and other isolated biological membranes indicates that the basolateral membrane urea permeability is fivefold lower than would be anticipated for its water permeability. These results indicate that the rectal gland maintains a selective barrier to urea in its basolateral membranes.

310. CAVEOLIN 1 AND 2 IN THE UTERUS DURING EARLY PREGNANCY

2010 ◽  
Vol 22 (9) ◽  
pp. 110
Author(s):  
R. J. Madawala ◽  
C. R. Murphy
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Protein Expression ◽  
Early Pregnancy ◽  
Basolateral Membrane ◽  
Membrane Curvature ◽  
Major Protein ◽  
Uterine Epithelial Cells ◽  
Caveolin 1 ◽  
Blastocyst Implantation

Rat uterine epithelial cells undergo many changes during early pregnancy in order to become receptive to blastocyst implantation. These changes include basolateral folding and the presence of vesicles of various sizes which are at their greatest number during the pre-implantation period. The present study investigated the possible role that caveolin 1 and 2 plays in this remodelling specifically days 1, 3, 6, 7, and 9 of pregnancy. Caveolin is a major protein in omega shaped invaginations of the plasma membrane called caveolae that are considered to be specialised plasma membrane subdomains. Caveolae are rich in cholesterol, glycosphingolipids, and GPI anchored proteins and are involved in endocytosis and membrane curvature. Immunofluorescence microscopy has shown caveolin 1 and 2 on day 1 of pregnancy are localised to the cytoplasm of luminal uterine epithelial cells, and by day 6 of pregnancy (the time of implantation), it concentrates basally. By day 9 of pregnancy, expression of both caveolin 1 and 2 in luminal uterine epithelia is cytoplasmic as seen on day 1 of pregnancy. A corresponding increase in protein expression of caveolin 1 on day 6 of pregnancy in luminal uterine epithelia was observed. Interestingly however, caveolin 2 protein expression decreases at the time of implantation as found by western blot analysis. Both caveolin 1 and 2 were localised to blood vessels within the endometrium and myometrium and also the muscle of the myometrium in all days of pregnancy studied. In addition, both caveolin 1 and 2 were absent from glandular epithelium, which is interesting considering that they do not undergo the plasma membrane transformation. The localisation and expression of caveolin 1 and 2 in rat luminal uterine epithelium at the time of implantation suggest possible roles in trafficking of cholesterol and/or various proteins for either degradation or relocation. Caveolins may contribute to the morphology of the basolateral membrane seen on day 6 of pregnancy. All of which may play an important role during successful blastocyst implantation.

ClC-2 in guinea pig colon: mRNA, immunolabeling, and functional evidence for surface epithelium localization

2002 ◽  
Vol 283 (4) ◽  
pp. G1004-G1013 ◽  
Author(s):  
Marcelo Catalán ◽  
Isabel Cornejo ◽  
Carlos D. Figueroa ◽  
María Isabel Niemeyer ◽  
Francisco V. Sepúlveda ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Guinea Pig ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Distal Colon ◽  
Surface Epithelium ◽  
Patch Clamp Technique ◽  
Chloride Currents ◽  
Kinetics Of

The principal function of the colon in fluid homeostasis is the absorption of NaCl and water. Apical membrane Na+ channels, Na+/H+ and Cl−/HCO[Formula: see text] exchangers, have all been postulated to mediate NaCl entry into colonocytes. The identity of the basolateral exit pathway for Cl− is unknown. We have previously demonstrated the presence of the ClC-2 transcript in the guinea pig intestine. Now we explore in more detail, the tissue and cellular distribution of chloride channel ClC-2 in the distal colon by in situ hybridization and immunohistochemistry. The patch-clamp technique was used to characterize Cl− currents in isolated surface epithelial cells from guinea pig distal colon and these were compared with those mediated by recombinant guinea pig (gp)ClC-2. ClC-2 mRNA and protein were found in the surface epithelium of the distal colon. Immunolocalization revealed that, in addition to some intracellular labeling, ClC-2 was present in the basolateral membranes but absent from the apical pole of colonocytes. Isolated surface epithelial cells exhibited hyperpolarization-activated chloride currents showing a Cl− > I− permeability and Cd2+ sensitivity. These characteristics, as well as some details of the kinetics of activation and deactivation, were very similar to those of recombinant gpClC-2 measured in parallel experiments. The presence of active ClC-2 type currents in surface colonic epithelium, coupled to a basolateral location for ClC-2 in the distal colon, suggests a role for ClC-2 channel in mediating basolateral membrane exit of Cl− as an essential step in a NaCl absorption process.

Identification of Na+/H+ exchange on the apical side of surface colonocytes using BCECF

1994 ◽  
Vol 267 (1) ◽  
pp. G119-G128 ◽  
Author(s):  
G. G. King ◽  
W. E. Lohrmann ◽  
J. W. Ickes ◽  
G. M. Feldman
Keyword(s):  
Apical Membrane ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Distal Colon ◽  
Transport Processes ◽  
Acetoxymethyl Ester ◽  
Apical Cell Membrane ◽  
Apical Side ◽  
Free Media ◽  
Phi Regulation

Colonocytes must regulate intracellular pH (pHi) while they transport H+ and HCO3-. To investigate the membrane transport processes involved in pHi regulation, colonocyte pHi was measured with 2,'7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) in intact segments of rat distal colon mounted on a holder that fits into a standard fluorometer cuvette and allows independent superfusion of mucosal and serosal surfaces. When NCECF-acetoxymethyl ester was in the mucosal solution only, BCECF loaded surface colonocytes with a high degree of selectivity. In HEPES-buffered solutions, basal pHi was 7.31 +/- 0.01 (n = 68), and pHi was dependent on extracellular Na+. Cells acidified in Na(+)-free solution, and pHi rapidly corrected when Na+ was returned. pHi recovered at 0.22 +/- 0.01 pH/min (n = 6) when Na+ was introduced into the mucosal solution and at 0.02 +/- 0.01 pH/min (n = 7) when Na+ was absent from the mucosal solution. The presence or absence of Na+ in the serosal solution did not affect pHi. This indicated that the Na(+)-dependent pHi recovery process is located in the apical cell membrane, but not in the basolateral membrane. Because amiloride (1 mM) inhibited Na(+)-dependent pHi recovery by 75%, Na+/H+ exchange appears to be present in the apical membrane. Because Na(+)-independent pHi recovery was not affected by K(+)-free media, 50 microM SCH-28080, 100 nM bafilomycin A1, or Cl(-)-free media, this transport mechanism does not involve a gastriclike H(+)-K(+)-ATPase, a vacuolar H(+)-ATPase, or a Cl-/base exchanger. In summary, pHi was selectively measured in surface colonocytes by this technique. In these cells, the Na+/H+ exchange activity involved in pHi regulation was detected in the apical membrane, but not in the basolateral membrane.

scholarly journals An Apical-Type Trafficking Pathway Is Present in Cultured Oligodendrocytes but the Sphingolipid-enriched Myelin Membrane Is the Target of a Basolateral-Type Pathway

1998 ◽  
Vol 9 (3) ◽  
pp. 599-609 ◽  
Author(s):  
Hans de Vries ◽  
Cobi Schrage ◽  
Dick Hoekstra
Keyword(s):  
Plasma Membrane ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Insoluble Fraction ◽  
Membrane Domains ◽  
Myelin Membrane ◽  
Influenza Virus Hemagglutinin ◽  
Polarized Cells ◽  
Vesicular Stomatitis ◽  
Triton X

Myelin sheets originate from distinct areas at the oligodendrocyte (OLG) plasma membrane and, as opposed to the latter, myelin membranes are relatively enriched in glycosphingolipids and cholesterol. The OLG plasma membrane can therefore be considered to consist of different membrane domains, as in polarized cells; the myelin sheet is reminiscent of an apical membrane domain and the OLG plasma membrane resembles the basolateral membrane. To reveal the potentially polarized membrane nature of OLG, the trafficking and sorting of two typical markers for apical and basolateral membranes, the viral proteins influenza virus–hemagglutinin (HA) and vesicular stomatitis virus–G protein (VSVG), respectively, were examined. We demonstrate that in OLG, HA and VSVG are differently sorted, which presumably occurs upon their trafficking through the Golgi. HA can be recovered in a Triton X-100-insoluble fraction, indicating an apical raft type of trafficking, whereas VSVG was only present in a Triton X-100-soluble fraction, consistent with its basolateral sorting. Hence, both an apical and a basolateral sorting mechanism appear to operate in OLG. Surprisingly, however, VSVG was found within the myelin sheets surrounding the cells, whereas HA was excluded from this domain. Therefore, despite its raft-like transport, HA does not reach a membrane that shows features typical of an apical membrane. This finding indicates either the uniqueness of the myelin membrane or the requirement of additional regulatory factors, absent in OLG, for apical delivery. These remarkable results emphasize that polarity and regulation of membrane transport in cultured OLG display features that are quite different from those in polarized cells.

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