Glycoconjugate distribution and mobility on apical membranes of absorptive cells of suckling rat ileum in vivo

1985 ◽  
Vol 213 (4) ◽  
pp. 520-528 ◽  
Author(s):  
Patricia A. Gonnella ◽  
Marian R. Neutra
Keyword(s):  
Rat Ileum ◽  
Absorptive Cells ◽  
Apical Membranes

Convergence of apical and basolateral endocytic pathways at apical late endosomes in absorptive cells of suckling rat ileum in vivo

1990 ◽  
Vol 97 (2) ◽  
pp. 385-394
Author(s):  
M. Fujita ◽  
F. Reinhart ◽  
M. Neutra
Keyword(s):  
Basolateral Membrane ◽  
Hydrolytic Enzymes ◽  
Membrane Domains ◽  
Rat Ileum ◽  
Absorptive Cells ◽  
Apical Side ◽  
Late Endosomes ◽  
Membrane Components ◽  
Endocytic Pathways

Absorptive cells of the intestinal epithelium endocytose proteins from both apical and basolateral membrane domains. In absorptive cells of suckling rat ileum, luminal protein tracers first enter an apical tubulovesicular endosomal system, then enter larger apical endosomal vesicles and multivesicular bodies (MVB), and finally are delivered to a giant supranuclear lysosomal vacuole. To determine whether proteins endocytosed from the basolateral domain in vivo enter the same endosomal or lysosomal compartments as those taken up from the apical side, we simultaneously applied cationized ferritin (CF) apically (by intra-luminal injection) and horseradish peroxidase (HRP) basally (by intravenous injection), and examined absorptive cells after 3 min to 60 min using light, electron and fluorescence microscopy. At early times, CF and HRP entered separate endosomal compartments at apical and basolateral poles. At no time did HRP enter the apical tubulovesicular system, and CF never entered early basolateral endosomes. After 15 min, however, both tracers appeared together in large late endosomes and MVB located apically, above the giant vacuole. From 15 to 60 min both tracers accumulated in the giant vacuole. Membranes of some apical late endosomes, all apical MVB, the giant vacuole, and occasional sub-nuclear vesicles contained immunoreactive Igp120, a glycoprotein specific to late compartments of the endosome-lysosome system. These results show that highly polarized intestinal epithelial cells have separate apical and basolateral early endosomal compartments, presumably to maintain distinct membrane domains while allowing endocytosis and recycling of membrane from both surfaces. Apical and basolateral endocytic pathways, and presumably vesicles delivering hydrolytic enzymes and lysosomal membrane components, converge at the apical late endosome.

scholarly journals Uptake and transepithelial transport of nerve growth factor in suckling rat ileum.

1986 ◽  
Vol 103 (5) ◽  
pp. 1979-1990 ◽  
Author(s):  
K Siminoski ◽  
P Gonnella ◽  
J Bernanke ◽  
L Owen ◽  
M Neutra ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Transepithelial Transport ◽  
Immunological Methods ◽  
Transport Pathway ◽  
Nerve Growth ◽  
Rat Ileum ◽  
Absorptive Cells

Nerve growth factor (NGF) is necessary for the development of sympathetic and some sensory neurons. Milk may be a source of NGF for suckling young, but sites of intestinal absorption of the protein have not been identified. To determine whether NGF is transported across the absorptive epithelium of suckling rat ileum, we assessed binding, uptake, and transport of 125I-NGF by light microscopy and EM autoradiography. Blood and tissue extracts were analyzed by biochemical and immunological methods to determine whether NGF was taken up structurally intact. NGF binding sites were identified on microvilli and apical invaginations of ileal absorptive cells in vitro. Injected into ileal loops in vivo, NGF radioactivity retained by fixation was evident after 20 min in apical regions of absorptive cells, in endocytic tubules (which mediate the uptake of membrane-bound ligands), in vesicles (which mediate nonspecific endocytosis), and in the supranuclear lysosomal vacuole. At 1 and 2 h, radiolabel in these compartments increased and silver grains were evident at the basal cell surface, and in cells, matrix, and vessels of the lamina propria. In blood and liver, radiolabeled molecules that were immunologically and electrophoretically indistinguishable from NGF and that co-eluted with NGF on gel filtration columns were detected, confirming that some NGF was transported across the epithelium structurally intact. Thus, absorptive cells of suckling rat ileum can take up NGF by both receptor-mediated and nonspecific endocytosis, and direct NGF either to the lysosome for degradation, or into a transepithelial transport pathway.

Surface binding and uptake of polycationic ferritin by neonatal piglet intestinal epithelium

1980 ◽  
Vol 46 (1) ◽  
pp. 235-252
Author(s):  
C.C. Chase ◽  
E.A. Munn
Keyword(s):  
Specific Interaction ◽  
Age Groups ◽  
Similar Distribution ◽  
Surface Binding ◽  
Protein Uptake ◽  
In Vivo Experiments ◽  
Absorptive Cells ◽  
Apical Vesicles

Pieces of small intestine from newborn, I- and 6-day-old piglets were incubated in vitro and ligated segments were incubated in vivo with polycationic ferritin (PCF) to determine the distribution and possible role in protein uptake of anionic sites on membranes at the luminal surfaces of the epithelial cells. Most PCF binding to the absorptive cells occurred on the upper third or half of the villi and to some non-absorptive cells (tuft cells) throughout the length of the villi. Pieces of intestine which were fixed before incubation had PCF on microvilli and apical invaginations of absorptive cells, but none in the sub-apical tubules. When samples were incubated with PCF in vitro before fixation PCF was bound to the surfaces of microvilli of absorptive cells and to the membranes lining the apical invaginations, some sub-apical vesicles and some sub-apical tubules in all age-groups. In vivo experiments with longer incubation times resulted in a similar distribution, with increased amounts of PCF in the sub-apical tubules in samples from newborn and 1-day-old piglets only. In the newborn there were small vesicles containing PCF which had apparently moved further into the cells. At the same concentration (2 mg/ml) ferritin did not enter the sub-apical tubules; but it did enter and was taken up by the cells in the presence of 4% (w/v) serum albumin. It is concluded that the mechanism of protein uptake does not involve the microvillar membrane and that non-specific interaction with the invaginated plasma membrane, as a function of charge-density, leads to opening of the sub-apical tubular system to protein. Movement further into the cell depends on other factors.

Inhibition of Bile Acid and Water Absorption by Phenethylbiguanide in Rat Ileum in vivo

Digestion ◽  
1975 ◽  
Vol 12 (3) ◽  
pp. 179-182 ◽  
Author(s):  
W.F. Caspary ◽  
H. Lücke
Keyword(s):  
Bile Acid ◽  
Water Absorption ◽  
Rat Ileum

Modulation of epithelial Na+ channel activity by long-chain n–3 fatty acids

2004 ◽  
Vol 287 (4) ◽  
pp. F850-F855 ◽  
Author(s):  
Frédérique Mies ◽  
Vadim Shlyonsky ◽  
Arnaud Goolaerts ◽  
Sarah Sariban-Sohraby
Keyword(s):  
Fatty Acids ◽  
Sodium Channels ◽  
Sodium Transport ◽  
Open Circuit ◽  
Na Channel ◽  
Open Probability ◽  
Endogenous Factors ◽  
Excised Patches ◽  
Apical Membranes

The epithelial sodium channel is found in apical membranes of a variety of native epithelial tissues, where it regulates sodium and fluid balance. In vivo, a number of hormones and other endogenous factors, including polyunsaturated fatty acids (PUFAs), regulate these channels. We tested the effects of essential n–3 and n–6 PUFAs on amiloride-sensitive sodium transport in A6 epithelial cells. Eicosapentaenoic acid [EPA; C20:5(n–3)] transiently stimulated amiloride-sensitive open-circuit current ( INa) from 4.0 ± 0.3 to 7.7 ± 0.3 μA/cm2 within 30 min ( P < 0.001). No activation was seen in the presence of 10 μM amiloride. In cell-attached but not in cell-excised patches, EPA acutely increased the open probability of sodium channels from 0.45 ± 0.08 to 0.63 ± 0.10 ( P = 0.02, paired t-test). n–6 PUFAs, including linoleic acid (C18:2), eicosatetraynoic acid (C20:4), and docosapentanoic acid (C22:5) had no effect, whereas n–3 docosahexanoic acid (C22:6) activated amiloride-sensitive INa in a manner similar to EPA. Activation of INa by EPA was prevented by H-89, a PKA inhibitor. Similarly, PKA activity was stimulated by EPA. Nonspecific stimulation of phosphodiesterase activity by CoCl2 completely prevented the effect of EPA on sodium transport. We conclude that n–3 PUFAs activate epithelial sodium channels downstream of cAMP in a cAMP-dependent pathway also involving PKA.

scholarly journals M-Cell Surface β1 Integrin Expression and Invasin-Mediated Targeting of Yersinia pseudotuberculosis to Mouse Peyer’s Patch M Cells

1998 ◽  
Vol 66 (3) ◽  
pp. 1237-1243 ◽  
Author(s):  
M. Ann Clark ◽  
Barry H. Hirst ◽  
Mark A. Jepson
Keyword(s):  
Cell Surface ◽  
Yersinia Pseudotuberculosis ◽  
M Cells ◽  
Β1 Integrin ◽  
Integrin Expression ◽  
Peyer’S Patch ◽  
Peyer's Patch ◽  
M Cell ◽  
Apical Membranes

ABSTRACT Quantitative analysis of Yersinia pseudotuberculosisinfection of murine gut loops revealed that significantly more wild-type bacteria associated with Peyer’s patch M cells than with dome enterocytes or goblet cells. An invasin-deficient mutant was significantly attenuated for M-cell invasion, while β1 integrin expression was demonstrated in the apical membranes of M cells but not enterocytes. M-cell targeting by Yersinia pseudotuberculosis in vivo may, therefore, be mediated primarily by the interaction of invasin with cell surface β1 integrins.

Phenol injury-induced hypertension stimulates proximal tubule Na+/H+ exchanger activity

2006 ◽  
Vol 290 (6) ◽  
pp. F1543-F1550 ◽  
Author(s):  
Patrick K. K. Leong ◽  
Li E. Yang ◽  
Carol S. Landon ◽  
Alicia A. McDonough ◽  
Kay-Pong Yip
Keyword(s):  
Proximal Tubule ◽  
Rate Of Change ◽  
Chronic Hypertension ◽  
Low Density ◽  
Acute Hypertension ◽  
Renal Sympathetic Nerve Activity ◽  
Fluorescence Dye ◽  
Apical Membranes ◽  
Renal Sympathetic

Injection of 50 μl 10% phenol into rat renal cortex activates renal sympathetic nerve activity which provokes acute hypertension that persists for weeks. We have previously shown with membrane fractionation that phenol injury caused a redistribution of the main proximal tubule (PT) apical transporter NHE3 (Na+/H+ exchanger isoform 3) to low density membranes enriched in apical microvilli. The aim of this study was to determine whether phenol injury increases PT apical Na+/H+ exchanger (NHE) activity. NHE activity was measured in vivo as the initial rate of change in intracellular pH (dpHi/d t) during luminal Na+ removal in PT preloaded with the pH-sensitive fluorescence dye BCECF. Injection of 50 μl 10% phenol increased blood pressure from 113 ± 5.2 to 130 ± 4.6 mmHg without changing glomerular filtration rate or urine output. NHE activity increased 2.6-fold by 70 min after phenol injury. The increase of NHE activity was accompanied with an increase of tubular reabsorption. Total NHE activity/NHE3 protein in cortical brush-border membrane (BBM) vesicles, measured by acridine orange quench and immunoblot, respectively, was unchanged by phenol injury. In conclusion, acute phenol injury provokes coincident increases in PT apical NHE activity, redistribution of NHE3 into low density apical membranes, and hypertension. The increase in NHE activity may contribute to the lack of pressure-diuresis and the maintenance of chronic hypertension in this model.

Loss of acidification of anterior prostate fluids inAtp12a-null mutant mice indicates that nongastric H-K-ATPase functions as proton pump in vivo

2006 ◽  
Vol 291 (2) ◽  
pp. C366-C374 ◽  
Author(s):  
Nikolay B. Pestov ◽  
Tatyana V. Korneenko ◽  
Mikhail I. Shakhparonov ◽  
Gary E. Shull ◽  
Nikolai N. Modyanov
Keyword(s):  
Proton Pump ◽  
Functional Expression ◽  
Α Subunit ◽  
Gene Ablation ◽  
Atpase Gene ◽  
Anterior Prostate ◽  
Null Mutant Mice ◽  
Apical Membranes ◽  
Prostate Epithelium

The physiological functions of nongastric (colonic) H-K-ATPase (gene symbol Atp12a), unlike those of Na-K-ATPase and gastric H-K-ATPase, are poorly understood. It has been suggested that it pumps Na+more efficiently than H+; however, so far, there is no direct evidence that it pumps H+in vivo. Previously, we found that the nongastric H-K-ATPase α-subunit is expressed in apical membranes of rodent anterior prostate epithelium, in a complex with the Na-K-ATPase β1-subunit. Here we report the effects of Atp12a gene ablation on polarization of the β1-subunit and secretory function of the anterior prostate. In nongastric H-K-ATPase-deficient prostate, the Na-K-ATPase α-subunit resided exclusively in basolateral membranes; however, the β1-subunit disappeared from apical membranes, demonstrating that β1is an authentic subunit of nongastric H-K-ATPase in vivo and that apical localization of β1in the prostate is completely dependent on its association with the nongastric H-K-ATPase α-subunit. A remarkable reduction in acidification of anterior prostate fluids was observed: pH 6.38 ± 0.14 for wild-type mice and 6.96 ± 0.10 for homozygous mutants. These results show that nongastric H-K-ATPase is required for acidification of luminal prostate fluids, thereby providing a strong in vivo correlate of previous functional expression studies demonstrating that it operates as a proton pump.

Cellular mechanism of aminoglycoside tolerance in long-term gentamicin treatment

1997 ◽  
Vol 272 (4) ◽  
pp. C1309-C1318 ◽  
Author(s):  
D. P. Sundin ◽  
C. Meyer ◽  
R. Dahl ◽  
A. Geerdes ◽  
R. Sandoval ◽  
...  
Keyword(s):  
Apical Membrane ◽  
Fluid Phase ◽  
Selective Inhibition ◽  
Membrane Lipid ◽  
Immunofluorescent Staining ◽  
Morphological Studies ◽  
Gentamicin Treatment ◽  
Apical Membranes

In the rat, nephrotoxicity results from uptake of gentamicin at the apical membrane of proximal tubule (PT) cells. However, during continuous gentamicin treatment, the PT epithelium has been shown to recover. The mechanism(s) of cellular recovery and development of tolerance remains unknown. Therefore, we undertook studies designed to characterize cellular adaptations that occur during long-term gentamicin (LTG) treatment. After 19 days of gentamicin treatment, electron microscopy morphological evaluation revealed cellular recovery with an apparent mild decrease in height and number of microvilli. Enzymatic analysis of LTG PT membranes showed that apical and basolateral membranes had essentially returned to normal. Analysis of apical membrane lipid content revealed persistent statistically significant (P < 0.01) elevations in phosphatidylinositol (PI). In vivo immunogold morphological studies and biochemical studies in LTG rats revealed that endocytosis of gentamicin was selectively reduced, whereas the markers of fluid-phase (horseradish peroxidase) and receptor-mediated (beta2-microglobulin) endocytoses were unaffected or increased. Biochemical analysis showed that, although gentamicin binding to apical membranes isolated from LTG rats increased greater than twofold (P < 0.05) over membranes from untreated rats, in vivo cellular uptake, quantified with [3H]gentamicin, was reduced. Western blot analysis of LTG apical membranes and immunofluorescent staining of perfusion-fixed LTG kidneys showed no change in megalin levels or its apical membrane localization. These data imply that recovery of PT cells from and tolerance to LTG treatment involve a selective inhibition of gentamicin uptake across the apical membrane. They indicate that the mediators of gentamicin endocytosis were affected differently: PI levels increased, whereas megalin levels did not change. We conclude that selective inhibition of gentamicin uptake during LTG treatment is not affected by a reduction in PI or megalin levels. We postulate that trafficking of gentamicin and/or gentamicin-containing endocytic structures is reduced in LTG rats, allowing cells to develop tolerance to gentamicin.

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