scholarly journals Distinct transport vesicles mediate the delivery of plasma membrane proteins to the apical and basolateral domains of MDCK cells.

1990 ◽  
Vol 111 (3) ◽  
pp. 987-1000 ◽  
Author(s):  
A Wandinger-Ness ◽  
M K Bennett ◽  
C Antony ◽  
K Simons

Immunoisolation techniques have led to the purification of apical and basolateral transport vesicles that mediate the delivery of proteins from the trans-Golgi network to the two plasma membrane domains of MDCK cells. We showed previously that these transport vesicles can be formed and released in the presence of ATP from mechanically perforated cells (Bennett, M. K., A. Wandinger-Ness, and K. Simons, 1988. EMBO (Euro. Mol. Biol. Organ.) J. 7:4075-4085). Using virally infected cells, we have monitored the purification of the trans-Golgi derived vesicles by following influenza hemagglutinin or vesicular stomatitis virus (VSV) G protein as apical and basolateral markers, respectively. Equilibrium density gradient centrifugation revealed that hemagglutinin containing vesicles had a slightly lower density than those containing VSV-G protein, indicating that the two fractions were distinct. Antibodies directed against the cytoplasmically exposed domains of the viral spike glycoproteins permitted the resolution of apical and basolateral vesicle fractions. The immunoisolated vesicles contained a subset of the proteins present in the starting fraction. Many of the proteins were sialylated as expected for proteins existing the trans-Golgi network. The two populations of vesicles contained a number of proteins in common, as well as components which were enriched up to 38-fold in one fraction relative to the other. Among the unique components, a number of transmembrane proteins could be identified using Triton X-114 phase partitioning. This work provides evidence that two distinct classes of vesicles are responsible for apical and basolateral protein delivery. Common protein components are suggested to be involved in vesicle budding and fusion steps, while unique components may be required for specific recognition events such as those involved in protein sorting and vesicle targeting.

1991 ◽  
Vol 112 (5) ◽  
pp. 823-831 ◽  
Author(s):  
Y Goda ◽  
S R Pfeffer

We have recently described a cell-free system that reconstitutes the vesicular transport of 300-kD mannose 6-phosphate receptors from late endosomes to the trans-Golgi network (TGN). We report here that the endosome----TGN transport reaction was significantly inhibited by low concentrations of the alkylating agent, N-ethylmaleimide (NEM). Addition of fresh cytosol to NEM-inactivated reaction mixtures restored transport to at least 80% of control levels. Restorative activity was only present in cytosol fractions, and was sensitive to trypsin treatment or incubation at 100 degrees C. A variety of criteria demonstrated that the restorative activity was distinct from NSF, an NEM-sensitive protein that facilitates the transport of proteins from the ER to the Golgi complex and between Golgi cisternae. Cytosol fractions immunodepleted of greater than or equal to 90% of NSF protein, or heated to 37 degrees C to inactivate greater than or equal to 93% of NSF activity, were fully able to restore transport to NEM-treated reaction mixtures. The majority of restorative activity sedimented as a uniform species of 50-100 kD upon glycerol gradient centrifugation. We have termed this activity ETF-1, for endosome----TGN transport factor-1. Kinetic experiments showed that ETF-1 acts at a very early stage in vesicular transport, which may reflect a role for this factor in the formation of nascent transport vesicles. GTP hydrolysis appears to be required throughout the transport reaction. The ability of GTP gamma S to inhibit endosome----TGN transport required the presence of donor, endosome membranes, and cytosol, which may reflect a role for guanine nucleotides in vesicle budding. Finally, ETF-1 appears to act before a step that is blocked by GTP gamma S, during the process by which proteins are transported from endosomes to the TGN in vitro.


1988 ◽  
Vol 106 (2) ◽  
pp. 253-267 ◽  
Author(s):  
B van Deurs ◽  
K Sandvig ◽  
OW Petersen ◽  
S Olsnes ◽  
K Simons ◽  
...  

We have used a protocol for internalization of ricin, a ligand binding to plasma membrane glycoproteins and glycolipids with terminal galactosyl residues, and infection with the vesicular stomatitis virus ts 045 mutant in BHK-21 cells to determine whether internalized plasma membrane molecules tagged by ricin reach distinct compartments of the biosynthetic-exocytic pathway. At 39.5 degrees C newly synthesized G protein of ts 045 was largely prevented from leaving the endoplasmic reticulum. At the same temperature ricin was endocytosed and reached, in addition to endosomes and lysosomes, elements of the Golgi complex. When the temperature was lowered to 19.5 degrees C, no more ricin was delivered to the Golgi complex, but now G protein accumulated in the Golgi stacks and the trans-Golgi network (TGN). Double-labeling immunogold cytochemistry on ultracryosections was used to detect G protein and ricin simultaneously. These data, combined with stereological and biochemical methods, showed that approximately 5% of the total amount of ricin within the cells, corresponding to 6-8 X 10(4) molecules per cell, colocalized with G protein in the Golgi complex after 60 min at 39.5 degrees C. Of this amount approximately 70-80% was present in the TGN. Since most of the ricin molecules remain bound to their binding sites at the low pH prevailing in compartments of the endocytic pathway, the results indicate that a fraction of the internalized plasma membrane molecules with terminal galactose are not recycled directly from endosomes or delivered to lysosomes, but are routed to the Golgi complex. Also, the results presented here, in combination with other recent studies on ricin internalization, suggest that translocation of the toxic ricin A-chain to the cytosol occurs in the TGN.


2007 ◽  
Vol 406 (1) ◽  
pp. 157-165 ◽  
Author(s):  
Alberto M. Díaz Añel

The requirement of DAG (diacylglycerol) to recruit PKD (protein kinase D) to the TGN (trans-Golgi network) for the targeting of transport carriers to the cell surface, has led us to a search for new components involved in this regulatory pathway. Previous findings reveal that the heterotrimeric Gβγ (GTP-binding protein βγ subunits) act as PKD activators, leading to fission of transport vesicles at the TGN. We have recently shown that PKCη (protein kinase Cη) functions as an intermediate member in the vesicle generating pathway. DAG is capable of activating this kinase at the TGN, and at the same time is able to recruit PKD to this organelle in order to interact with PKCη, allowing phosphorylation of PKD's activation loop. The most qualified candidates for the production of DAG at the TGN are PI-PLCs (phosphatidylinositol-specific phospholipases C), since some members of this family can be directly activated by Gβγ, utilizing PtdIns(4,5)P2 as a substrate, to produce the second messengers DAG and InsP3. In the present study we show that βγ-dependent Golgi fragmentation, PKD1 activation and TGN to plasma membrane transport were affected by a specific PI-PLC inhibitor, U73122 [1-(6-{[17-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2,5-dione]. In addition, a recently described PI-PLC activator, m-3M3FBS [2,4,6-trimethyl-N-(m-3-trifluoromethylphenyl)benzenesulfonamide], induced vesiculation of the Golgi apparatus as well as PKD1 phosphorylation at its activation loop. Finally, using siRNA (small interfering RNA) to block several PI-PLCs, we were able to identify PLCβ3 as the sole member of this family involved in the regulation of the formation of transport carriers at the TGN. In conclusion, we demonstrate that fission of transport carriers at the TGN is dependent on PI-PLCs, specifically PLCβ3, which is necessary to activate PKCη and PKD in that Golgi compartment, via DAG production.


1990 ◽  
Vol 111 (6) ◽  
pp. 2893-2908 ◽  
Author(s):  
D Gravotta ◽  
M Adesnik ◽  
D D Sabatini

A procedure employing streptolysin O to effect the selective permeabilization of either the apical or basolateral plasma membrane domains of MDCK cell monolayers grown on a filter support was developed which permeabilizes the entire monolayer, leaves the opposite cell surface domain intact, and does not abolish the integrity of the tight junctions. This procedure renders the cell interior accessible to exogenous macromolecules and impermeant reagents, permitting the examination of their effects on membrane protein transport to the intact surface. The last stages of the transport of the influenza virus hemagglutinin (HA) to the apical surface were studied in pulse-labeled, virus-infected MDCK cells that were incubated at 19.5 degrees C for 90 min to accumulate newly synthesized HA in the trans-Golgi network (TGN), before raising the temperature to 35 degrees C to allow synchronized transport to the plasma membrane. In cells permeabilized immediately after the cold block, 50% of the intracellular HA molecules were subsequently delivered to the apical surface. This transport was dependent on the presence of an exogenous ATP supply and was markedly inhibited by the addition of GTP-gamma-S at the time of permeabilization. On the other hand, the GTP analogue had no effect when it was added to cells that, after the cold block, were incubated for 15 min at 35 degrees C before permeabilization, even though at this time most HA molecules were still intracellular and their appearance at the cell surface was largely dependent on exogenous ATP. These findings indicate that GTP-binding proteins are involved in the constitutive process that effects vesicular transport from the TGN to the plasma membrane and that they are charged early in this process. Transport of HA to the cell surface could be made dependent on the addition of exogenous cytosol when, after permeabilization, cells were washed to remove endogenous cytosolic components. This opens the way towards the identification of cell components that mediate the sorting of apical and basolateral membrane components in the TGN and their polarized delivery to the cell surface.


2001 ◽  
Vol 12 (6) ◽  
pp. 1623-1631 ◽  
Author(s):  
Jack Rohrer ◽  
Rosalind Kornfeld

A crucial step in lysosomal biogenesis is catalyzed by “uncovering” enzyme (UCE), which removes a coveringN-acetylglucosamine from the mannose 6-phosphate (Man-6-P) recognition marker on lysosomal hydrolases. This study shows that UCE resides in the trans-Golgi network (TGN) and cycles between the TGN and plasma membrane. The cytosolic domain of UCE contains two potential endocytosis motifs: 488YHPL and C-terminal 511NPFKD. YHPL is shown to be the more potent of the two in retrieval of UCE from the plasma membrane. A green-fluorescent protein-UCE transmembrane-cytosolic domain fusion protein colocalizes with TGN 46, as does endogenous UCE in HeLa cells, showing that the transmembrane and cytosolic domains determine intracellular location. These data imply that the Man-6-P recognition marker is formed in the TGN, the compartment where Man-6-P receptors bind cargo and are packaged into clathrin-coated vesicles.


1999 ◽  
Vol 112 (11) ◽  
pp. 1721-1732 ◽  
Author(s):  
M.J. Francis ◽  
E.E. Jones ◽  
E.R. Levy ◽  
R.L. Martin ◽  
S. Ponnambalam ◽  
...  

The protein encoded by the Menkes disease gene (MNK) is localised to the Golgi apparatus and cycles between the trans-Golgi network and the plasma membrane in cultured cells on addition and removal of copper to the growth medium. This suggests that MNK protein contains active signals that are involved in the retention of the protein to the trans-Golgi network and retrieval of the protein from the plasma membrane. Previous studies have identified a signal involved in Golgi retention within transmembrane domain 3 of MNK. To identify a motif sufficient for retrieval of MNK from the plasma membrane, we analysed the cytoplasmic domain, downstream of transmembrane domain 7 and 8. Chimeric constructs containing this cytoplasmic domain fused to the reporter molecule CD8 localised the retrieval signal(s) to 62 amino acids at the C terminus. Further studies were performed on putative internalisation motifs, using site-directed mutagenesis, protein expression, chemical treatment and immunofluorescence. We observed that a di-leucine motif (L1487L1488) was essential for rapid internalisation of chimeric CD8 proteins and the full-length Menkes cDNA from the plasma membrane. We suggest that this motif mediates the retrieval of MNK from the plasma membrane into the endocytic pathway, via the recycling endosomes, but is not sufficient on its own to return the protein to the Golgi apparatus. These studies provide a basis with which to identify other motifs important in the sorting and delivery of MNK from the plasma membrane to the Golgi apparatus.


1996 ◽  
Vol 133 (3) ◽  
pp. 543-558 ◽  
Author(s):  
A Müsch ◽  
H Xu ◽  
D Shields ◽  
E Rodriguez-Boulan

Current model propose that in nonpolarized cells, transport of plasma membrane proteins to the surface occurs by default. In contrast, compelling evidence indicates that in polarized epithelial cells, plasma membrane proteins are sorted in the TGN into at least two vectorial routes to apical and basolateral surface domains. Since both apical and basolateral proteins are also normally expressed by both polarized and nonpolarized cells, we explored here whether recently described basolateral sorting signals in the cytoplasmic domain of basolateral proteins are recognized and used for post TGN transport by nonpolarized cells. To this end, we compared the inhibitory effect of basolateral signal peptides on the cytosol-stimulated release of two basolateral and one apical marker in semi-intact fibroblasts (3T3), pituitary (GH3), and epithelial (MDCK) cells. A basolateral signal peptide (VSVGp) corresponding to the 29-amino acid cytoplasmic tail of vesicular stomatitis virus G protein (VSVG) inhibited with identical potency the vesicular release of VSVG from the TGN of all three cell lines. On the other hand, the VSVG peptide did not inhibit the vesicular release of HA in MDCK cells not of two polypeptide hormones (growth hormone and prolactin) in GH3 cells, whereas in 3T3 cells (influenza) hemagglutinin was inhibited, albeit with a 3x lower potency than VSVG. The results support the existence of a basolateral-like, signal-mediated constitutive pathway from TGN to plasma membrane in all three cell types, and suggest that an apical-like pathway may be present in fibroblast. The data support cargo protein involvement, not bulk flow, in the formation of post-TGN vesicles and predict the involvement of distinct cytosolic factors in the assembly of apical and basolateral transport vesicles.


Science ◽  
2006 ◽  
Vol 313 (5793) ◽  
pp. 1591-1594 ◽  
Author(s):  
M. A. McNiven ◽  
H. M. Thompson

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