237. Aquaporins in rat uterine epithelial cells during early pregnancy and in response to progesterone

2005 ◽  
Vol 17 (9) ◽  
pp. 93
Author(s):  
L. A. Lindsay ◽  
C. R. Murphy

Implantation of the rat blastocyst is a highly regulated process, involving transformation of the uterine environment into one which is receptive to an implanting blastocyst. At the time of implantation, in response to progesterone, there is a dramatic decrease in the amount of uterine luminal fluid leading to close apposition between the luminal epithelium and trophoblastic cells. The rat blastocyst also always implants at the antimesometrial pole of the uterine lumen and currently mechanisms regulating this process are unknown. Aquaporins, a family of transmembrane water channels, are involved in the regulation of water movement across epithelial barriers. We investigated several aquaporins in the rat uterus during early pregnancy using reverse transcriptase PCR. Immunofluorescence and immunogold electron microscopy techniques were then used to investigate the localisation of particular aquaporins including AQP5 in the uterine epithelium during early pregnancy and in ovariectomised rats treated with progesterone. There was an increase in AQP5 molecules in the apical plasma membrane of luminal epithelial cells at the time of implantation, with a greater increase at the mesometrial compared to antimesometrial pole. A similar result was seen in luminal epithelial cells from ovariectomised rats treated with progesterone, however there was no differential concentration between mesometrial and antimesometrial poles, as there was during early pregnancy. It is suggested that the increase in AQP5 protein expression in the apical plasma membrane of luminal epithelial cells is involved in reabsorption of luminal fluid at the time of implantation. Furthermore, the differential concentration of AQP5 on luminal epithelial cells at the time of implantation could lead to the establishment of a fluid gradient within the uterine lumen and hence lead to the asymmetrical implantation position of the rat blastocyst.

2017 ◽  
Vol 29 (6) ◽  
pp. 1194 ◽  
Author(s):  
Samson N. Dowland ◽  
Romanthi J. Madawala ◽  
Connie E. Poon ◽  
Laura A. Lindsay ◽  
Christopher R. Murphy

In preparation for uterine receptivity, the uterine epithelial cells (UECs) exhibit a loss of microvilli and glycocalyx and a restructuring of the actin cytoskeleton. The prominin-1 protein contains large, heavily glycosylated extracellular loops and is usually restricted to apical plasma membrane (APM) protrusions. The present study examined rat UECs during early pregnancy using immunofluorescence, western blotting and deglycosylation analyses. Ovariectomised rats were injected with oestrogen and progesterone to examine how these hormones affect prominin-1. At the time of fertilisation, prominin-1 was located diffusely in the apical domain of UECs and 147- and 120-kDa glycoforms of prominin-1 were identified, along with the 97-kDa core protein. At the time of implantation, prominin-1 concentrates towards the APM and densitometry revealed that the 120-kDa glycoform decreased (P < 0.05), but there was an increase in the 97-kDa core protein (P < 0.05). Progesterone treatment of ovariectomised rats resulted in prominin-1 becoming concentrated towards the APM. The 120-kDa glycoform was increased after oestrogen treatment (P < 0.0001), whereas the 97-kDa core protein was increased after progesterone treatment (P < 0.05). Endoglycosidase H analysis demonstrated that the 120-kDa glycoform is in the endoplasmic reticulum, undergoing protein synthesis. These results indicate that oestrogen stimulates prominin-1 production, whereas progesterone stimulates the deglycosylation and concentration of prominin-1 to the apical region of the UECs. This likely presents the deglycosylated extracellular loops of prominin-1 to the extracellular space, where they may interact with the implanting blastocyst.


2010 ◽  
Vol 22 (9) ◽  
pp. 112
Author(s):  
S. N. Dowland ◽  
L. A. Lindsay ◽  
C. R. Murphy

Prominin-1 is a recently discovered pentaspan membrane protein present in characteristic cholesterol-based vesicles and associated with microvilli. These vesicles are used to deliver prominin-1 to the apical plasma membrane in a number of cell types. Previous work on uterine epithelial cells has demonstrated a loss of microvilli and the presence of large, cholesterol-based vesicles at the time of implantation. Thus this study aims to determine a role for prominin-1 in rat uterine epithelial cells during early pregnancy. Immunofluorescence microscopy reveals punctate and diffuse prominin-1 staining below the apical plasma membrane on day 1 of pregnancy. At the time of blastocyst implantation (day 6) however, prominin-1 appears concentrated at the apical surface of the cell. Western blotting of isolated uterine epithelial cell lysate revealed a change in prominin-1 glycosylation during early pregnancy. Prominin-1 was determined to be glycosylated on day 1 of pregnancy, but these carbohydrate side chains were lost by the time of attachment. Results seen in the present study indicate that prominin-containing vesicles may be prevented from reaching the apical plasma membrane by the terminal web on day 1 of pregnancy. On day 6, the loss of the terminal web may allow the vesicles to approach and incorporate into the apical plasma membrane, as seen with other uterine vesicles. The deglycosylation of prominin-1 at this time is suggested to allow the protein to bind its ligand and activate downstream signalling pathways that permit implantation. This study constitutes the first reported observation of prominin in endometrial lumenal epithelial cells. These preliminary results, in consideration with previous reports of prominin expression in trophoblast cells, suggest an important role for this protein in early pregnancy.


2005 ◽  
Vol 17 (9) ◽  
pp. 94
Author(s):  
M. D. O. Nicholson ◽  
C. R. Murphy

Regulation of the uterine luminal environment is important for the successful attachment and implantation of the blastocyst. Tight junctions regulate the paracellular pathway between epithelial cells lining the uterine lumen and the uterine glands. The aims of this present study was firstly to establish the presence and cellular distribution of claudins and occludin in the luminal epithelia during early pregnancy using immunofluorescence microscopy and deconvolution, and secondly to determine the influence of ovarian hormones on their expression. Occludin and claudins -1, -3, and -4 were present in luminal epithelium. Occludin and claudin-4 showed increased expression in luminal epithelium at the time of implantation, whereas claudin-1 and -3 expression remained the same throughout early pregnancy. In ovariectomised rats administered ovarian hormones, occludin and claudin-4 showed increased expression in luminal epithelium in progesterone-dominant regimes and decreased expression when administered oestrogen alone. Expression of claudin-1 and -3 in luminal epithelium was not effected by ovarian hormones. Claudin-2 was not expressed during early pregnancy nor in ovariectomised rats. In conclusion, these results show that occludin and claudins -1, -3 and -4 are present in luminal and glandular epithelium, and provide the permeability properties needed to separate the luminal and the stromal environment at the time of implantation. Furthermore, occludin and claudin-4 expression is controlled by ovarian hormones being upregulated by progesterone.


1998 ◽  
Vol 9 (6) ◽  
pp. 1437-1448 ◽  
Author(s):  
Thierry Galli ◽  
Ahmed Zahraoui ◽  
Vadakkanchery V. Vaidyanathan ◽  
Graça Raposo ◽  
Jian Min Tian ◽  
...  

The importance of soluble N-ethyl maleimide (NEM)-sensitive fusion protein (NSF) attachment protein (SNAP) receptors (SNAREs) in synaptic vesicle exocytosis is well established because it has been demonstrated that clostridial neurotoxins (NTs) proteolyze the vesicle SNAREs (v-SNAREs) vesicle-associated membrane protein (VAMP)/brevins and their partners, the target SNAREs (t-SNAREs) syntaxin 1 and SNAP25. Yet, several exocytotic events, including apical exocytosis in epithelial cells, are insensitive to numerous clostridial NTs, suggesting the presence of SNARE-independent mechanisms of exocytosis. In this study we found that syntaxin 3, SNAP23, and a newly identified VAMP/brevin, tetanus neurotoxin (TeNT)-insensitive VAMP (TI-VAMP), are insensitive to clostridial NTs. In epithelial cells, TI-VAMP–containing vesicles were concentrated in the apical domain, and the protein was detected at the apical plasma membrane by immunogold labeling on ultrathin cryosections. Syntaxin 3 and SNAP23 were codistributed at the apical plasma membrane where they formed NEM-dependent SNARE complexes with TI-VAMP and cellubrevin. We suggest that TI-VAMP, SNAP23, and syntaxin 3 can participate in exocytotic processes at the apical plasma membrane of epithelial cells and, more generally, domain-specific exocytosis in clostridial NT-resistant pathways.


2009 ◽  
Vol 21 (3) ◽  
pp. 408 ◽  
Author(s):  
R. E. Lloyd ◽  
R. M. A. Elliott ◽  
A. Fazeli ◽  
P. F. Watson ◽  
W. V. Holt

Following insemination, ram spermatozoa are transported to the isthmus region of the oviduct where they bind to the oviductal epithelial cells (OEC), remaining viable for several hours. The aim of the present study was to begin to decipher which component(s) of the ewe oviduct actively participates in maintaining the viability of ram spermatozoa. A series of experiments was conducted to investigate whether: (1) soluble OEC apical plasma membrane proteins (sAPM) isolated from ewes prolong survival of ram spermatozoa over an extended (48 h) coincubation period at 39°C; (2) a recombinant form of one of these oviductal proteins, namely heat shock 70 kDa protein 8 (HSPA8), prolongs survival of ram spermatozoa; and (3) pretreatment with HSPA8 antibody compromises the ability of sAPM to prolong the survival of ram spermatozoa. Both sAPM and recombinant HSPA8 had a beneficial effect on the viability of ram spermatozoa during coincubation, although both these effects were dose dependent. In contrast, pretreatment with HSPA8 antibody significantly negated the ability of sAPM to maintain the viability of ram spermatozoa. These findings suggest that HSPA8 is an active component of the ewe oviduct that participates in maintaining the viability of ram spermatozoa. This is a potentially valuable observation given that there is a great deal of room for improving existing diluents for storing fresh ram semen.


1982 ◽  
Vol 55 (1) ◽  
pp. 1-12
Author(s):  
C.R. Murphy ◽  
J.G. Swift ◽  
T.M. Mukherjee ◽  
A.W. Rogers

In previous work we have shown that ovarian hormones, when injected into ovariectomized rats, alter the fine structure of the plasma membrane of endometrial epithelial cells. In this paper freeze-fractures have been used to study the apical plasma membrane of endometrial epithelial cells of rats during the period of blastocyst implantation of normal pregnancy. On day 1 of pregnancy there were 2354 +/− 114 intramembranous particles (IMPs) per micrometer2 of membrane. The particles were spherical and randomly distributed. On day 5 of pregnancy IMP density rose to 2899 +/− 289 per micrometer2 and some rod-shaped particles were also visible. By day 6 of pregnancy IMP density had risen to 4014 +/− 206 per micrometer2 and there were more rod-shaped IMPs than before. In addition, on day 6 IMPs were also present as rows of particles and some gap-junction-like arrays of particles were also seen. Our findings indicate that there are fine-structural alterations in the apical plasma membrane of endometrial epithelial cells, the site of first contact between maternal and embryonic cells, during the period of early pregnancy. The findings are discussed in the light of suggested mechanisms of blastocyst attachment to the uterine epithelium at implantation.


2001 ◽  
Vol 114 (7) ◽  
pp. 1331-1341 ◽  
Author(s):  
A.K. Criss ◽  
D.M. Ahlgren ◽  
T.S. Jou ◽  
B.A. McCormick ◽  
J.E. Casanova

The bacterial pathogen Salmonella typhimurium colonizes its animal hosts by inducing its internalization into intestinal epithelial cells. This process requires reorganization of the actin cytoskeleton of the apical plasma membrane into elaborate membrane ruffles that engulf the bacteria. Members of the Ρ family of small GTPases are critical regulators of actin structure, and in nonpolarized cells, the GTPase Cdc42 has been shown to modulate Salmonella entry. Because the actin architecture of epithelial cells is organized differently from that of nonpolarized cells, we examined the role of two ‘Rgr; family GTPases, Cdc42 and Rac1, in invasion of polarized monolayers of MDCK cells by S. typhimurium. Surprisingly, we found that endogenous Rac1, but not Cdc42, was activated during bacterial entry at the apical pole, and that this activation required the bacterial effector protein SopE. Furthermore, expression of dominant inhibitory Rac1 but not Cdc42 significantly inhibited apical internalization of Salmonella, indicating that Rac1 activation is integral to the bacterial entry process. In contrast, during basolateral internalization, both Cdc42 and Rac1 were activated; however, neither GTPase was required for entry. These findings, which differ significantly from previous observations in nonpolarized cells, indicate that the host cell signaling pathways activated by bacterial pathogens may vary with cell type, and in epithelial tissues may further differ between plasma membrane domains.


Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1057
Author(s):  
Richard Bouley ◽  
Naofumi Yui ◽  
Abby Terlouw ◽  
Pui W. Cheung ◽  
Dennis Brown

We previously showed that in polarized Madin–Darby canine kidney (MDCK) cells, aquaporin-2 (AQP2) is continuously targeted to the basolateral plasma membrane from which it is rapidly retrieved by clathrin-mediated endocytosis. It then undertakes microtubule-dependent transcytosis toward the apical plasma membrane. In this study, we found that treatment with chlorpromazine (CPZ, an inhibitor of clathrin-mediated endocytosis) results in AQP2 accumulation in the basolateral, but not the apical plasma membrane of epithelial cells. In MDCK cells, both AQP2 and clathrin were concentrated in the basolateral plasma membrane after CPZ treatment (100 µM for 15 min), and endocytosis was reduced. Then, using rhodamine phalloidin staining, we found that basolateral, but not apical, F-actin was selectively reduced by CPZ treatment. After incubation of rat kidney slices in situ with CPZ (200 µM for 15 min), basolateral AQP2 and clathrin were increased in principal cells, which simultaneously showed a significant decrease of basolateral compared to apical F-actin staining. These results indicate that clathrin-dependent transcytosis of AQP2 is an essential part of its trafficking pathway in renal epithelial cells and that this process can be inhibited by selectively depolymerizing the basolateral actin pool using CPZ.


1990 ◽  
Vol 1 (12) ◽  
pp. 921-936 ◽  
Author(s):  
M J van Zeijl ◽  
K S Matlin

The effects of microtubule perturbation on the transport of two different viral glycoproteins were examined in infected Madin-Darby canine kidney (MDCK) cells grown on both permeable and solid substrata. Quantitative biochemical analysis showed that the microtubule-depolymerizing drug nocodazole inhibited arrival of influenza hemagglutinin on the apical plasma membrane in MDCK cells grown on both substrata. In contrast, the microtubule-stabilizing drug taxol inhibited apical appearance of hemagglutinin only when MDCK cells were grown on permeable substrata. On the basis of hemagglutinin mobility on sodium dodecyl sulfate gels and its sensitivity to endo H, it was evident that nocodazole and taxol arrested hemagglutinin at different intracellular sites. Neither drug caused a significant increase in the amount of hemagglutinin detected on the basolateral plasma membrane domain. In addition, neither drug had any noticeable effect on the transport of the vesicular stomatitis virus (VSV)-G protein to the basolateral surface. These results shed light on previous conflicting reports using this model system and support the hypothesis that microtubules play a role in the delivery of membrane glycoproteins to the apical, but not the basolateral, domain of epithelial cells.


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