Isoform specific expression of the neuronal F-actin binding protein, drebrin, in specialized cells of stomach and kidney epithelia

2000 ◽  
Vol 113 (2) ◽  
pp. 325-336 ◽  
Author(s):  
B.H. Keon ◽  
P.T. Jedrzejewski ◽  
D.L. Paul ◽  
D.A. Goodenough

To further understand the functional role that the F-actin binding protein, drebrin (developmentally regulated brain protein), plays in the regulation of F-actin, we characterized its expression in non-neuronal cells. Using nanoelectrospray mass spectrometry methods, we initially identified drebrin in non-neuronal cultured cells. Using a drebrin-specific monoclonal antibody, we were able to detect drebrin protein in several different cell lines derived from fibroblasts, astrocytomas, and simple epithelia, but not in cell lines derived from stratified epithelia. Double-label immunofluorescence experiments of cultured cell monolayers revealed the localization of drebrin at the apical plasma membrane together with a pool of submembranous F-actin. Immunoblot analysis of mouse organs revealed that, in addition to its high levels of expression in brain, drebrin was present in stomach and to a lesser degree in kidney, colon, and urinary bladder. Drebrin protein detected in the non-brain organs migrated faster through SDS-PAGE gels, indicating that the lower molecular weight embryonic brain isoform (E2) may be the prominent isoform in these organs. RT-PCR experiments confirmed the specific expression of the E2 isoform in adult stomach, kidney, and cultured cells. In situ immunofluorescence experiments revealed a cell-type specific pattern in both stomach and kidney. In stomach, drebrin was specifically expressed in the acid-secreting parietal cells of the fundic glands, where it accumulated at the extended apical membrane of the canaliculi. In kidney, drebrin was expressed in acid-secreting type A intercalated cells, where it localized specifically to the apical plasma membrane. Drebrin was expressed as well in the distal tubule epithelial cells where the protein was concentrated at the luminal surface and present at the interdigitations of the basolateral membranes.

2001 ◽  
Vol 12 (6) ◽  
pp. 1595-1609 ◽  
Author(s):  
Shigekazu Yokoyama ◽  
Kouichi Tachibana ◽  
Hiroyuki Nakanishi ◽  
Yasunori Yamamoto ◽  
Kenji Irie ◽  
...  

ZO-1 is an actin filament (F-actin)–binding protein that localizes to tight junctions and connects claudin to the actin cytoskeleton in epithelial cells. In nonepithelial cells that have no tight junctions, ZO-1 localizes to adherens junctions (AJs) and may connect cadherin to the actin cytoskeleton indirectly through β- and α-catenins as one of many F-actin–binding proteins. Nectin is an immunoglobulin-like adhesion molecule that localizes to AJs and is associated with the actin cytoskeleton through afadin, an F-actin–binding protein. Ponsin is an afadin- and vinculin-binding protein that also localizes to AJs. The nectin-afadin complex has a potency to recruit the E-cadherin–β-catenin complex through α-catenin in a manner independent of ponsin. By the use of cadherin-deficient L cell lines stably expressing various components of the cadherin-catenin and nectin-afadin systems, and α-catenin–deficient F9 cell lines, we examined here whether nectin recruits ZO-1 to nectin-based cell-cell adhesion sites. Nectin showed a potency to recruit not only α-catenin but also ZO-1 to nectin-based cell-cell adhesion sites. This recruitment of ZO-1 was dependent on afadin but independent of α-catenin and ponsin. These results indicate that ZO-1 localizes to cadherin-based AJs through interactions not only with α-catenin but also with the nectin-afadin system.


1990 ◽  
Vol 38 (8) ◽  
pp. 1145-1153 ◽  
Author(s):  
J H Hartwig ◽  
D Brown ◽  
D A Ausiello ◽  
T P Stossel ◽  
L Orci

Vasopressin regulates transepithelial osmotic water permeability in the kidney collecting duct and in target cells in other tissues. In the presence of hormone, water channels are inserted into an otherwise impermeable apical plasma membrane and the apical surface of these cells is dramatically remodelled. Because cytochalasin B and D greatly reduce the response of these cells to vasopressin, actin filaments are believed to participate in the events leading to an increase in transepithelial water permeability. Modulation of the actin filamentous network requires the concerted action of specific actin regulatory proteins, and in the present study we used protein A-gold immunocytochemistry to localize two important molecules, gelsolin and actin binding protein (ABP), in epithelial cells of the kidney inner medulla. Gelsolin and, to a lesser extent, ABP were concentrated in clusters in the apical cell web of principal cells of the collecting duct. Aggregates of gold particles were often associated with the cytoplasmic side of plasma membrane regions forming surface extensions or microvilli. The basolateral plasma membrane was labeled to a much lesser extent than the apical plasma membrane. In the thin limbs of Henle, ABP was localized over the apical plasma membrane in ascending limbs, but gelsolin labeling was weak in these cells. In thin descending limbs, the pattern of labeling was completely reversed, with abundant apical gelsolin labeling but only weak ABP immunolabeling. Although the significance of the distribution of actin regulatory proteins in thin limbs is unknown, the abundance and the predominantly apical polarization of both ABP and gelsolin in principal cells of the collecting duct is consistent with a role of the actin cytoskeleton in the mechanism of vasopressin actin.


2010 ◽  
Vol 298 (4) ◽  
pp. F935-F940 ◽  
Author(s):  
Janet D. Klein ◽  
Mitsi A. Blount ◽  
Otto Fröhlich ◽  
Chad E. Denson ◽  
Xiaoxiao Tan ◽  
...  

Vasopressin is the primary hormone regulating urine-concentrating ability. Vasopressin phosphorylates the UT-A1 urea transporter in rat inner medullary collecting ducts (IMCDs). To assess the effect of UT-A1 phosphorylation at S486, we developed a phospho-specific antibody to S486-UT-A1 using an 11 amino acid peptide antigen starting from amino acid 482 that bracketed S486 in roughly the center of the sequence. We also developed two stably transfected mIMCD3 cell lines: one expressing wild-type UT-A1 and one expressing a mutated form of UT-A1, S486A/S499A, that is unresponsive to protein kinase A. Forskolin stimulates urea flux in the wild-type UT-A1-mIMCD3 cells but not in the S486A/S499A-UT-A1-mIMCD3 cells. The phospho-S486-UT-A1 antibody identified UT-A1 protein in the wild-type UT-A1-mIMCD3 cells but not in the S486A/S499A-UT-A1-mIMCD3 cells. In rat IMCDs, forskolin increased the abundance of phospho-S486-UT-A1 (measured using the phospho-S486 antibody) and of total UT-A1 phosphorylation (measured by 32P incorporation). Forskolin also increased the plasma membrane accumulation of phospho-S486-UT-A1 in rat IMCD suspensions, as measured by biotinylation. In rats treated with vasopressin in vivo, the majority of the phospho-S486-UT-A1 appears in the apical plasma membrane. In summary, we developed stably transfected mIMCD3 cell lines expressing UT-A1 and an S486-UT-A1 phospho-specific antibody. We confirmed that vasopressin increases UT-A1 accumulation in the apical plasma membrane and showed that vasopressin phosphorylates UT-A1 at S486 in rat IMCDs and that the S486-phospho-UT-A1 form is primarily detected in the apical plasma membrane.


1990 ◽  
Vol 111 (2) ◽  
pp. 483-493 ◽  
Author(s):  
J E Fox ◽  
C D Austin ◽  
J K Boyles ◽  
P K Steffen

The platelet plasma membrane is lined by a membrane skeleton that appears to contain short actin filaments cross-linked by actin-binding protein. Actin-binding protein is in turn associated with specific plasma membrane glycoproteins. The aim of this study was to determine whether the membrane skeleton regulates properties of the plasma membrane. Platelets were incubated with agents that disrupted the association of the membrane skeleton with membrane glycoproteins. The consequences of this change on plasma membrane properties were examined. The agents that were used were ionophore A23187 and dibucaine. Both agents activated calpain (the Ca2(+)-dependent protease), resulting in the hydrolysis of actin-binding protein and decreased association of actin with membrane glycoproteins. Disruption of actin-membrane interactions was accompanied by the shedding of procoagulant-rich microvesicles from the plasma membrane. The shedding of microvesicles correlated with the hydrolysis of actin-binding protein and the disruption of actin-membrane interactions. When the calpain-induced disruption of actin-membrane interactions was inhibited, the shedding of microvesicles was inhibited. These data are consistent with the hypothesis that association of the membrane skeleton with the plasma membrane maintains the integrity of the plasma membrane, preventing the shedding of procoagulant-rich microvesicles from the membrane of unstimulated platelets. They raise the possibility that the procoagulant-rich microvesicles that are released under a variety of physiological and pathological conditions may result from the dissociation of the platelet membrane skeleton from its membrane attachment sites.


Author(s):  
J. Aggeler ◽  
J.E. Heuser ◽  
Z. Werb

Phagocytosis of particles by macrophages may be similar to cell spreading on a substratum, in that a dense network of actin filaments appears beneath the plasma membrane in both cases. When viewed in broken-open or detergent- extracted cells, cytoskeletal filaments are observed to form focal attachments to the plasma membrane and to the cytoplasmic surface of phagosomes. Hartwig et al. have presented a model of phagocytosis in which an actin-binding protein alters the organization of subplasmalemma1 actin filaments in such a way that the plasma membrane is forced up over the particle to form the phagosome. Their evidence indicates that similar actin-binding proteins may function during cell spreading.


1988 ◽  
Vol 106 (5) ◽  
pp. 1525-1538 ◽  
Author(s):  
J E Fox ◽  
J K Boyles ◽  
M C Berndt ◽  
P K Steffen ◽  
L K Anderson

Platelets have previously been shown to contain actin filaments that are linked, through actin-binding protein, to the glycoprotein (GP) Ib-IX complex, GP Ia, GP IIa, and an unidentified GP of Mr 250,000 on the plasma membrane. The objective of the present study was to use a morphological approach to examine the distribution of these membrane-bound filaments within platelets. Preliminary experiments showed that the Triton X-100 lysis buffers used previously to solubilize platelets completely disrupt the three-dimensional organization of the cytoskeletons. Conditions were established that minimized these postlysis changes. The cytoskeletons remained as platelet-shaped structures. These structures consisted of a network of long actin filaments and a more amorphous layer that outlined the periphery. When Ca2+ was present, the long actin filaments were lost but the amorphous layer at the periphery remained; conditions were established in which this amorphous layer retained the outline of the platelet from which it originated. Immunocytochemical experiments showed that the GP Ib-IX complex and actin-binding protein were associated with the amorphous layer. Analysis of the amorphous material on SDS-polyacrylamide gels showed that it contained actin, actin-binding protein, and all actin-bound GP Ib-IX. Although actin filaments could not be visualized in thin section, the actin presumably was in a filamentous form because it was solubilized by DNase I and bound phalloidin. These studies show that platelets contain a membrane skeleton and suggest that it is distinct from the network of cytoplasmic actin filaments. This membrane skeleton exists as a submembranous lining that, by analogy to the erythrocyte membrane skeleton, may stabilize the plasma membrane and contribute to determining its shape.


1995 ◽  
Vol 270 (2) ◽  
pp. 596-602 ◽  
Author(s):  
Frank Hanakam ◽  
Christoph Eckerskorn ◽  
Friedrich Lottspeich ◽  
Annette Müller-Taubenberger ◽  
Wolfram Schäfer ◽  
...  

1987 ◽  
Author(s):  
J M Wilkinson ◽  
N Hack ◽  
L I Thorsen ◽  
J A Thomas

Platelet membrane preparations can be fractionated into two major subpopulations by free flow electrophoresis and these have been shown to correspond to the plasma membrane and the endoplasmic reticulum of the platelet. The plasma membrane fraction can be shown, by two-dimensional electrophoresis, to contain the major surface glycoproteins together with considerable amounts of actin and actin-associated proteins such as the 250 kDa actin-binding protein (filamin), P235 (talin), myosin, α-actinin and tropomyosin (Hack, N. … Crawford, N., Biochem. J. 222, 235 (1984). These cytoskeletal proteins are associated with the cytoplasmic face of the plasma membrane and probably interact with transmembrane glycoproteins. We have raised monoclonal antibodies to the purified plasma membrane preparation in order to investigate the nature of these glycoprotein-cytoskeletal interactions. In two fusion experiments, out of 804 tested, 104 hybrids secreted antibody to the membrane preparation and of these 24 were selected for further study. Initial assays were by ELISA using either the membrane preparation or whole fixed platelets as the target antigen. The specificity of the antibodies was investigated further by immunoblotting of SDS gels of total platelet proteins prepared under reducing and nonreducing conditions, by immunofluorescence, by immunohisto-chemistry and by crossed immunoelectrophoresis. The majority of the antibodies recognise major surface glycoproteins; of these, four bind to glycoprotein Ib under all conditions examined while another seven recognise the glycoprotein IIb/IIIa complex as detected by crossed immunoelectrophoresis. Three antibodies recognise the actin binding protein and these cross-react with the smooth muscle protein filamin in a number of different species. Further characterisation of these antibodies in both structural and functional terms will be presented.We are grateful to the Smith and Nephew Foundation for financial support for these studies


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