Role of redox systems on Fe3+ uptake by transformed human intestinal epithelial (Caco-2) cells

1994 ◽  
Vol 267 (6) ◽  
pp. C1582-C1588 ◽  
Author(s):  
M. T. Nunez ◽  
X. Alvarez ◽  
M. Smith ◽  
V. Tapia ◽  
J. Glass
Keyword(s):  
Plasma Membrane ◽  
Transepithelial Transport ◽  
Intestinal Epithelial ◽  
Parallel Mechanisms ◽  
Redox Systems ◽  
Basolateral Side ◽  
Fe Uptake ◽  
Human Intestinal Epithelium ◽  
Reduction Capacity

Caco-2 cells were used as a model of human intestinal epithelium to investigate the role of redox systems in transepithelial transport of 59Fe3+. The cells reduced Fe3+ present in the apical medium; the reduction was 50% inhibited by adriamycin and p-chloromercuribenzoate. Addition of [14C]ascorbate to the basolateral medium resulted in accumulation of 14C radioactivity in both cells and apical medium; apical radioactivity increased with time and was probably caused by paracellular flux. The cells provided Fe3+ reduction capacity to the apical incubation medium. Addition of ascorbate to the basolateral medium increased this reduction capacity 2-fold and the cellular uptake of 59Fe3+ 1.8-fold. Adriamycin significantly inhibited both cellular 59Fe uptake and Fe transport into the basolateral side. The results indicate that Caco-2 cells reduce apical Fe3+ by two parallel mechanisms: by a plasma membrane ferrireductase and by the secretion of reductants of either cellular or basolateral origin. The data support a model for Fe3+ intestinal absorption in which cell-mediated Fe3+ reduction occurs before cellular Fe uptake.

The GTPase Rac1 selectively regulates Salmonella invasion at the apical plasma membrane of polarized epithelial cells

2001 ◽  
Vol 114 (7) ◽  
pp. 1331-1341 ◽  
Author(s):  
A.K. Criss ◽  
D.M. Ahlgren ◽  
T.S. Jou ◽  
B.A. McCormick ◽  
J.E. Casanova
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Mdck Cells ◽  
Bacterial Pathogen ◽  
Small Gtpases ◽  
Apical Plasma Membrane ◽  
Membrane Domains ◽  
Intestinal Epithelial ◽  
Actin Structure

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.

scholarly journals Endocytosis of Intestinal Tight Junction Proteins: In Time and Space

2020 ◽  
Author(s):  
Prashant Nighot ◽  
Thomas Ma
Keyword(s):  
Plasma Membrane ◽  
Cell Adhesion ◽  
Intracellular Trafficking ◽  
Intestinal Epithelial ◽  
Dynamic Regulation ◽  
Physiological Processes ◽  
Vital Functions ◽  
Inflammatory Bowel ◽  
Endocytic Regulation

Abstract Eukaryotic cells take up macromolecules and particles from the surrounding milieu and also internalize membrane proteins via a precise process of endocytosis. The role of endocytosis in diverse physiological processes such as cell adhesion, cell signaling, tissue remodeling, and healing is well recognized. The epithelial tight junctions (TJs), present at the apical lateral membrane, play a key role in cell adhesion and regulation of paracellular pathway. These vital functions of the TJ are achieved through the dynamic regulation of the presence of pore and barrier-forming proteins within the TJ complex on the plasma membrane. In response to various intracellular and extracellular clues, the TJ complexes are actively regulated by intracellular trafficking. The intracellular trafficking consists of endocytosis and recycling cargos to the plasma membrane or targeting them to the lysosomes for degradation. Increased intestinal TJ permeability is a pathological factor in inflammatory bowel disease (IBD), and the TJ permeability could be increased due to the altered endocytosis or recycling of TJ proteins. This review discusses the current information on endocytosis of intestinal epithelial TJ proteins. The knowledge of the endocytic regulation of the epithelial TJ barrier will provide further understanding of pathogenesis and potential targets for IBD and a wide variety of human disease conditions.

scholarly journals Cellular polarity asymmetrically functionalizes pathogen recognition receptor-mediated intrinsic immune response in human intestinal epithelium cells

2018 ◽  
Author(s):  
Megan L. Stanifer ◽  
Stephanie Muenchau ◽  
Markus Mukenhirn ◽  
Kalliopi Pervolaraki ◽  
Takashi Kanaya ◽  
...  
Keyword(s):  
Immune Response ◽  
Intestinal Tract ◽  
Intestinal Epithelial ◽  
Cellular Polarity ◽  
Basolateral Side ◽  
Integral Role ◽  
Human Intestinal Epithelium ◽  
Epithelium Cells ◽  
Pathogen Recognition Receptor ◽  
Recognition Receptor

SummaryIntestinal epithelial cells (IECs) act as a physical barrier separating the commensal-containing intestinal tract from the sterile interior. These cells have found a complex balance allowing them to be prepared for pathogen attacks while still tolerating the presence of bacteria/viral stimuli present in the lumen of the gut. Using primary human IECs, we probed the mechanisms, which allow for such a tolerance. We discovered that viral infection emanating from the basolateral side of IECs elicited a stronger intrinsic immune response as compared to lumenal apical infection. We determined that this asymmetric immune response was driven by the clathrin-sorting adapter AP-1B which mediates the polarized sorting of Toll-like receptor 3 (TLR3) toward the basolateral side of IECs. Mice and human IECs lacking AP-1B showed an exacerbated immune response following apical stimulation. Together these results suggest a model where the cellular polarity program plays an integral role in the ability of IECs to partially tolerate apical commensals while remaining fully responsive against invasive basolateral pathogens.

Intestinal epithelial CD23 mediates enhanced antigen transport in allergy: evidence for novel splice forms

2003 ◽  
Vol 285 (1) ◽  
pp. G223-G234 ◽  
Author(s):  
Linda C. H. Yu ◽  
Guillaume Montagnac ◽  
Ping-Chang Yang ◽  
Daniel H. Conrad ◽  
Alexandre Benmerah ◽  
...  
Keyword(s):  
Transepithelial Transport ◽  
Intestinal Epithelial ◽  
Rt Pcr ◽  
Ige Receptor ◽  
Ige Receptors ◽  
Elevated Expression ◽  
Antigen Transport ◽  
Isoform B ◽  
Splice Forms

We previously demonstrated enhanced transepithelial antigen transport in the intestine of allergic rodents associated with elevated expression of the low-affinity IgE receptor CD23 on enterocytes. Here, we examined the role of CD23 in the transport phenomenon using CD23–/– mice and characterized the isoform of intestinal epithelial CD23. Jejunal segments of sensitized mice were challenged with antigen. Enhanced transepithelial antigen transport and transmucosal antigen flux were found in the intestine of sensitized CD23+/+ but not CD23–/– mice. RT-PCR showed that enterocytes expressed only the isoform b of CD23. Sequencing revealed classic and alternative CD23 b transcripts lacking exon 5 ( bΔ 5) or 6, all of which were translated into functional IgE receptors. The protein encoded by bΔ 5 but not the classic b transcript was able to mediate the uptake of anti-CD23 or IgE, whereas both CD23 proteins were internalized after binding to IgE/antigen complexes. Our results suggest that the classic and alternative forms of CD23 b display distinct endocytic properties, suggesting that they are likely to play different roles in transepithelial transport of IgE and allergens.

scholarly journals Microtubular organization and its involvement in the biogenetic pathways of plasma membrane proteins in Caco-2 intestinal epithelial cells.

1991 ◽  
Vol 113 (2) ◽  
pp. 275-288 ◽  
Author(s):  
T Gilbert ◽  
A Le Bivic ◽  
A Quaroni ◽  
E Rodriguez-Boulan
Keyword(s):  
Plasma Membrane ◽  
Steady State ◽  
Membrane Proteins ◽  
Cell Surface ◽  
Colchicine Treatment ◽  
Apical Plasma Membrane ◽  
Apical Surface ◽  
Intestinal Epithelial ◽  
Plasma Membrane Proteins ◽  
Basolateral Side

We characterized the three-dimensional organization of microtubules in the human intestinal epithelial cell line Caco-2 by laser scanning confocal microscopy. Microtubules formed a dense network approximately 4-microns thick parallel to the cell surface in the apical pole and a loose network 1-micron thick in the basal pole. Between the apical and the basal bundles, microtubules run parallel to the major cell axis, concentrated in the vicinity of the lateral membrane. Colchicine treatment for 4 h depolymerized 99.4% of microtubular tubulin. Metabolic pulse chase, in combination with domain-selective biotinylation, immune and streptavidin precipitation was used to study the role of microtubules in the sorting and targeting of four apical and one basolateral markers. Apical proteins have been recently shown to use both direct and transcytotic (via the basolateral membrane) routes to the apical surface of Caco-2 cells. Colchicine treatment slowed down the transport to the cell surface of apical and basolateral proteins, but the effect on the apical proteins was much more drastic and affected both direct and indirect pathways. The final effect of microtubular disruption on the distribution of apical proteins depended on the degree of steady-state polarization of the individual markers in control cells. Aminopeptidase N (APN) and sucrase-isomaltase (SI), which normally reach a highly polarized distribution (110 and 75 times higher on the apical than on the basolateral side) were still relatively polarized (9 times) after colchicine treatment. The decrease in the polarity of APN and SI was mostly due to an increase in the residual basolateral expression (10% of control total surface expression) since 80% of the newly synthesized APN was still transported, although at a slower rate, to the apical surface in the absence of microtubules. Alkaline phosphatase and dipeptidylpeptidase IV, which normally reach only low levels of apical polarity (four times and six times after 20 h chase, nine times and eight times at steady state) did not polarize at all in the presence of colchicine due to slower delivery to the apical surface and increased residence time in the basolateral surface. Colchicine-treated cells displayed an ectopic localization of microvilli or other apical markers in the basolateral surface and large intracellular vacuoles. Polarized secretion into apical and basolateral media was also affected by microtubular disruption. Thus, an intact microtubular network facilitates apical protein transport to the cell surface of Caco-2 cells via direct and indirect routes; this role appears to be crucial for the final polarity of some apical plasma membrane proteins but only an enhancement factor for others.

scholarly journals Intracellular Cl− as a signaling ion that potently regulates Na+/HCO3− transporters

2015 ◽  
Vol 112 (3) ◽  
pp. E329-E337 ◽  
Author(s):  
Nikolay Shcheynikov ◽  
Aran Son ◽  
Jeong Hee Hong ◽  
Osamu Yamazaki ◽  
Ehud Ohana ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Mammalian Cells ◽  
Ion Homeostasis ◽  
Transport Processes ◽  
Transepithelial Transport ◽  
High Affinity ◽  
Dependent Site ◽  
Receptor Binding Protein

Cl− is a major anion in mammalian cells involved in transport processes that determines the intracellular activity of many ions and plasma membrane potential. Surprisingly, a role of intracellular Cl− (Cl−in) as a signaling ion has not been previously evaluated. Here we report that Cl−in functions as a regulator of cellular Na+ and HCO3− concentrations and transepithelial transport through modulating the activity of several electrogenic Na+-HCO3− transporters. We describe the molecular mechanism(s) of this regulation by physiological Cl−in concentrations highlighting the role of GXXXP motifs in Cl− sensing. Regulation of the ubiquitous Na+-HCO3− co-transport (NBC)e1-B is mediated by two GXXXP-containing sites; regulation of NBCe2-C is dependent on a single GXXXP motif; and regulation of NBCe1-A depends on a cryptic GXXXP motif. In the basal state NBCe1-B is inhibited by high Cl−in interacting at a low affinity GXXXP-containing site. IP3 receptor binding protein released with IP3 (IRBIT) activation of NBCe1-B unmasks a second high affinity Cl−in interacting GXXXP-dependent site. By contrast, NBCe2-C, which does not interact with IRBIT, has a single high affinity N-terminal GXXP-containing Cl−in interacting site. NBCe1-A is unaffected by Cl−in between 5 and 140 mM. However, deletion of NBCe1-A residues 29–41 unmasks a cryptic GXXXP-containing site homologous with the NBCe1-B low affinity site that is involved in inhibition of NBCe1-A by Cl−in. These findings reveal a cellular Cl−in sensing mechanism that plays an important role in the regulation of Na+ and HCO3− transport, with critical implications for the role of Cl− in cellular ion homeostasis and epithelial fluid and electrolyte secretion.

Role of Exosomes in the Exchange of Spermatozoa after Leaving the Seminiferous Tubule: A Review

2020 ◽  
Vol 21 (5) ◽  
pp. 330-338
Author(s):  
Luming Wu ◽  
Yuan Ding ◽  
Shiqiang Han ◽  
Yiqing Wang
Keyword(s):  
Drug Delivery ◽  
Plasma Membrane ◽  
Seminiferous Tubule ◽  
Metabolic Diseases ◽  
Inflammatory Diseases ◽  
Multivesicular Bodies ◽  
Extensive Search ◽  
Neurological Research ◽  
The One

Background: Exosomes are extracellular vesicles (EVs) released from cells upon fusion of an intermediate endocytic compartment with the plasma membrane. They refer to the intraluminal vesicles released from the fusion of multivesicular bodies with the plasma membrane. The contents and number of exosomes are related to diseases such as metabolic diseases, cancer and inflammatory diseases. Exosomes have been used in neurological research as a drug delivery tool and also as biomarkers for diseases. Recently, exosomes were observed in the seminal plasma of the one who is asthenozoospermia, which can affect sperm motility and capacitation. Objective: The main objective of this review is to deeply discuss the role of exosomes in spermatozoa after leaving the seminiferous tubule. Methods: We conducted an extensive search of the literature available on relationships between exosomes and exosomes in spermatozoa on the bibliographic database. Conclusion: : This review thoroughly discussed the role that exosomes play in the exchange of spermatozoa after leaving the seminiferous tubule and its potential as a drug delivery tool and biomarkers for diseases as well.

Prevention of Dextran Sulfate Sodium-induced Mouse Colitis by a Fungal Protein Ling Zhi-8 via Promoting the Barrier Function of Intestinal Epithelial Cells

2021 ◽  
Author(s):  
Yu-Huan Chen ◽  
Jenn-Yeu Shin ◽  
Hsiu-Mei Wei ◽  
Chi-Chen Lin ◽  
Linda Chia-Hui Yu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Immune Cells ◽  
Ganoderma Lucidum ◽  
Dextran Sulfate ◽  
Dextran Sulfate Sodium ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Fungal Protein ◽  
Fungal Immunomodulatory Protein

A fungal immunomodulatory protein Ling Zhi-8 (LZ-8) isolated from Ganoderma lucidum (GL) regulates immune cells and inhibits tumor growth; however, the role of LZ-8 in intestinal epithelial cells (IECs) is...

scholarly journals PRKAR2A deficiency protects mice from experimental colitis by increasing IFN-stimulated gene expression and modulating the intestinal microbiota

2021 ◽  
Author(s):  
Lumin Wei ◽  
Rongjing Zhang ◽  
Jinzhao Zhang ◽  
Juanjuan Li ◽  
Deping Kong ◽  
...  
Keyword(s):  
Experimental Colitis ◽  
Regulatory Subunit ◽  
Protective Effects ◽  
Intestinal Epithelial ◽  
Catalytic Subunits ◽  
Regulatory Subunits ◽  
Pka Regulatory Subunit ◽  
Cross Fostering ◽  
Specific Deletion

AbstractProtein kinase A (PKA) plays an important role in regulating inflammation via its catalytic subunits. Recently, PKA regulatory subunits have been reported to directly modulate some signaling pathways and alleviate inflammation. However, the role of PKA regulatory subunits in colonic inflammation remains unclear. Therefore, we conducted this study to investigate the role of the PKA regulatory subunit PRKAR2A in colitis. We observed that PRKAR2A deficiency protected mice from dextran sulfate sodium (DSS)-induced experimental colitis. Our experiments revealed that the intestinal epithelial cell-specific deletion of Prkar2a contributed to this protection. Mechanistically, the loss of PRKAR2A in Prkar2a−/− mice resulted in an increased IFN-stimulated gene (ISG) expression and altered gut microbiota. Inhibition of ISGs partially reversed the protective effects against DSS-induced colitis in Prkar2a−/− mice. Antibiotic treatment and cross-fostering experiments demonstrated that the protection against DSS-induced colitis in Prkar2a−/− mice was largely dependent on the gut microflora. Altogether, our work demonstrates a previously unidentified function of PRKAR2A in promoting DSS-induced colitis.

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