The role of regulated CFTR trafficking in epithelial secretion

2003 ◽  
Vol 285 (1) ◽  
pp. C1-C18 ◽  
Author(s):  
Carol A. Bertrand ◽  
Raymond A. Frizzell
Keyword(s):  
Epithelial Cells ◽  
Membrane Trafficking ◽  
Cellular Localization ◽  
Secretory Pathway ◽  
Molecular Mechanisms ◽  
Experimental Manipulation ◽  
Experimental Conditions ◽  
Functional Studies ◽  
Cellular Context ◽  
Polarized Epithelial Cells

The focus of this review is the regulated trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) in distal compartments of the protein secretory pathway and the question of how changes in CFTR cellular distribution may impact on the functions of polarized epithelial cells. We summarize data concerning the cellular localization and activity of CFTR and attempt to synthesize often conflicting results from functional studies of regulated endocytosis and exocytosis in CFTR-expressing cells. In some instances, findings that are inconsistent with regulated CFTR trafficking may result from the use of overexpression systems or nonphysiological experimental conditions. Nevertheless, judging from data on other transporters, an appropriate cellular context is necessary to support regulated CFTR trafficking, even in epithelial cells. The discovery that disease mutations can influence CFTR trafficking in distal secretory and recycling compartments provides support for the concept that regulated CFTR recycling contributes to normal epithelial function, including the control of apical CFTR channel density and epithelial protein secretion. Finally, we propose molecular mechanisms for regulated CFTR endocytosis and exocytosis that are based on CFTR interactions with other proteins, particularly those whose primary function is membrane trafficking. These models provide testable hypotheses that may lead to elucidation of CFTR trafficking mechanisms and permit their experimental manipulation in polarized epithelial cells.

scholarly journals Membrane Traffic in Aspergillus oryzae and Related Filamentous Fungi

2021 ◽  
Vol 7 (7) ◽  
pp. 534
Author(s):  
Yujiro Higuchi
Keyword(s):  
Filamentous Fungi ◽  
Aspergillus Oryzae ◽  
Protein Secretion ◽  
Membrane Trafficking ◽  
Secretory Pathway ◽  
Molecular Mechanisms ◽  
Membrane Traffic ◽  
Industrial Applications ◽  
Endocytic Pathway ◽  
Great Ability

The industrially important filamentous fungus Aspergillus oryzae, known as the yellow Koji mold and also designated the Japanese National fungus, has been investigated for understanding the intracellular membrane trafficking machinery due to the great ability of valuable enzyme production. The underlying molecular mechanisms of the secretory pathway delineate the main secretion route from the hyphal tip via the vesicle cluster Spitzenkörper, but also there is a growing body of evidence that septum-directed and unconventional secretion occurs in A. oryzae hyphal cells. Moreover, not only the secretory pathway but also the endocytic pathway is crucial for protein secretion, especially having a role in apical endocytic recycling. As a hallmark of multicellular filamentous fungal cells, endocytic organelles early endosome and vacuole are quite dynamic: the former exhibits constant long-range motility through the hyphal cells and the latter displays pleiomorphic structures in each hyphal region. These characteristics are thought to have physiological roles, such as supporting protein secretion and transporting nutrients. This review summarizes molecular and physiological mechanisms of membrane traffic, i.e., secretory and endocytic pathways, in A. oryzae and related filamentous fungi and describes the further potential for industrial applications.

171 CELLULAR EXPRESSION, LOCALIZATION, AND SECRETION OF OVINE Mx2 (oMx2) IN OVINE GLANDULAR EPITHELIAL CELLS (oGE)

2007 ◽  
Vol 19 (1) ◽  
pp. 202
Author(s):  
K. Toyokawa ◽  
A. M. Assiri ◽  
T. L. Ott
Keyword(s):  
Epithelial Cells ◽  
Cellular Localization ◽  
Secretory Pathway ◽  
Fold Increase ◽  
Cellular Functions ◽  
Immunofluorescence Analysis ◽  
Cellular Expression ◽  
Conditioned Culture Medium ◽  
High Level

Mx proteins are antiviral proteins that belong to the dynamin super-family of large GTPases. In a number of species Mx proteins were shown to be important components of the innate response to viral infection. Work in our laboratory showed that during early pregnancy Mx proteins are up-regulated in the ruminant uterus by conceptus-derived IFN tau. Transient oMx1 knockdown in ovine glandular epithelial cells (oGE) reduced oMx1 secretion and secretion of other unconventionally secreted proteins without affecting secretion via the classical secretory pathway. We further showed that oMx1 was present in uterine flushes from pregnant ewes. We recently characterized another Mx protein, oMx2, in sheep. The newly characterized oMx2 has higher homology with bovine Mx2 (93%) than with oMx1 (60%). The purpose of this study was to characterize cellular expression and localization of oMx2 in oGE cells and in cell lines derived from the luminal epithelium (oLE) and stroma (oSC). In addition we determined if oMx2 was secreted by oGE cells in vitro. Expressions of oMx1 and oMx2 were low to undetectable in all three lines in the absence of IFN tau and were increased by IFN tau (P < 0.01). Induction of oMx1 was greatest in oGE cells (8.4-fold increase; P < 0.01), whereas expression of oMx2 was greatest in oSC cells (19.9-fold increase; P < 0.01). Immunofluorescence analysis confirmed the high level of expression of oMx1 and oMx2 in response to IFN tau in oGE cells. Immunofluorescence analysis revealed that oMx2 co-localized with lamin A/C and nucleoporins, whereas oMx1 was distributed throughout the cytoplasm in oGE cells, suggesting that oMx2 is a nuclear membrane-associated protein. SignalP analysis indicated that oMx2 lacked a traditional leader sequence. Using an inhibitor of the classical secretory pathway, Monensin, we showed that oMx2 levels were not reduced in response to Monensin treatment. The oMx1, oMx2, and ISG15 levels in oGE-conditioned culture medium actually increased in secretions in response to Monensin (2.7-fold, 4.6-fold, and 2.9-fold increases, respectively; P < 0.1), whereas there was no effect of Monensin on �2MG levels (P > 0.1). Results show that oMx2 expression, like that of oMx1, is regulated by IFN tau. The functional significance of the different cellular localization between oMx1 and oMx2 is not clear, but may suggest that these related proteins possess distinct cellular functions. Finally, this is the first report that oMx2 is secreted, perhaps via poorly described unconventional secretory pathways. The potential intracellular and extracellular functions of oMx2 are currently being investigated. This work was supported by USDA grant 2002-02398 and NIH NCRR grant P20-RR15587-01 to T.L.O.

Targeting of Rab GTPases to cellular membranes

2005 ◽  
Vol 33 (4) ◽  
pp. 652-656 ◽  
Author(s):  
B.R. Ali ◽  
M.C. Seabra
Keyword(s):  
Membrane Trafficking ◽  
Cellular Localization ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Small Gtpases ◽  
Rab Proteins ◽  
Rab Gtpases ◽  
Cellular Membranes ◽  
Structural Determinants ◽  
Cellular Processes

Rab proteins are members of the superfamily of Ras-like small GTPases and are involved in several cellular processes relating to membrane trafficking and organelle mobility throughout the cell. Like other small GTPases, Rab proteins are initially synthesized as soluble proteins and for membrane attachment they require the addition of lipid moiety(ies) to specific residues of their polypeptide chain. Despite their well-documented roles in regulating cellular trafficking, Rab proteins own trafficking is still poorly understood. We still need to elucidate the molecular mechanisms of their recruitment to cellular membranes and the structural determinants for their specific cellular localization. Recent results indicate that Rab cellular targeting might be Rab-dependent, and this paper briefly reviews our current knowledge of this process.

Downregulation of cilia-localized Il-6Rα by 17β-estradiol in mouse and human fallopian tubes

2009 ◽  
Vol 297 (1) ◽  
pp. C140-C151 ◽  
Author(s):  
Ruijin Shao ◽  
Magdalena Nutu ◽  
Linda Karlsson-Lindahl ◽  
Anna Benrick ◽  
Birgitta Weijdegård ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Fallopian Tube ◽  
Knockout Mice ◽  
Cellular Localization ◽  
Molecular Mechanisms ◽  
Fallopian Tubes ◽  
Female Reproduction ◽  
Specific Expression ◽  
17Β Estradiol ◽  
Specific Regulation

The action of interleukin-6 (IL-6) impacts female reproduction. Although IL-6 was recently shown to inhibit cilia activity in human fallopian tubes in vitro, the molecular mechanisms underlying IL-6 signaling to tubal function remain elusive. Here, we investigate the cellular localization, regulation, and possible function of two IL-6 receptors (IL-6Rα and gp130) in mouse and human fallopian tubes in vivo. We show that IL-6Rα is restricted to the cilia of epithelial cells in both mouse and human fallopian tubes. Exogenous 17β-estradiol (E2), but not progesterone (P4), causes a time-dependent decrease in IL-6Rα expression, which is blocked by the estrogen receptor (ER) antagonist ICI-182,780. Exposure of different ER-selective agonists propyl-(1H)-pyrazole-1,3,5-triyl-trisphenol or 2,3-bis-(4-hydroxyphenyl)-propionitrile demonstrated an ER subtype-specific regulation of IL-6Rα in mouse fallopian tubes. In contrast to IL-6Rα, gp130 was detected in tubal epithelial cells in mice but not in humans. In humans, gp130 was found in the muscle cells and was decreased in the periovulatory and luteal phases during the reproductive cycles, indicating a species-specific expression and regulation of gp130 in the fallopian tube. Expression of tubal IL-6Rα and gp130 in IL-6 knockout mice was found to be normal; however, E2 treatment increased IL-6Rα, but not gp130, in IL-6 knockout mice when compared with wild-type mice. Furthermore, expression levels of IL-6Rα, but not gp130, decreased in parallel with estrogenic accelerated oocyte-cumulus complex (OCC) transport in mouse fallopian tubes. Our findings open the posibility that cilia-specific IL-6Rα may play a role in the regulation of OCC transport and suggest an estrogen-regulatory pathway of IL-6Rα in the fallopian tube.

scholarly journals Dual pulse-chase microscopy reveals early divergence in the biosynthetic trafficking of the Na,K-ATPase and E-cadherin

2015 ◽  
Vol 26 (24) ◽  
pp. 4401-4411 ◽  
Author(s):  
Glen A. Farr ◽  
Michael Hull ◽  
Emily H. Stoops ◽  
Rosalie Bateson ◽  
Michael J. Caplan
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Golgi Complex ◽  
Plasma Membranes ◽  
Secretory Pathway ◽  
Trans Golgi Network ◽  
Polarized Epithelial Cells ◽  
Golgi Network ◽  
E Cadherin

Recent evidence indicates that newly synthesized membrane proteins that share the same distributions in the plasma membranes of polarized epithelial cells can pursue a variety of distinct trafficking routes as they travel from the Golgi complex to their common destination at the cell surface. In most polarized epithelial cells, both the Na,K-ATPase and E-cadherin are localized to the basolateral domains of the plasma membrane. To examine the itineraries pursued by newly synthesized Na,K-ATPase and E-cadherin in polarized MDCK epithelial cells, we used the SNAP and CLIP labeling systems to fluorescently tag temporally defined cohorts of these proteins and observe their behaviors simultaneously as they traverse the secretory pathway. These experiments reveal that E-cadherin is delivered to the cell surface substantially faster than is the Na,K-ATPase. Furthermore, the surface delivery of newly synthesized E-cadherin to the plasma membrane was not prevented by the 19°C temperature block that inhibits the trafficking of most proteins, including the Na,K-ATPase, out of the trans-Golgi network. Consistent with these distinct behaviors, populations of newly synthesized E-cadherin and Na,K-ATPase become separated from one another within the trans-Golgi network, suggesting that they are sorted into different carrier vesicles that mediate their post-Golgi trafficking.

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