Maintenance of epithelial surface membrane lipid polarity: A role for differing phospholipid translocation rates

Molitoris, Bruce A.; Simon, Francis R.

doi:10.1007/bf01901012

Cited by 10 publications

(6 citation statements)

References 25 publications

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“…In all cases specific activities of intracellular organelle marker enzymes were less than the corresponding homogenates and there were no differences between control and experimental membrane fractions. Lipids from 0.5 to I mg of apical membrane protein were extracted in 6 ml of chloroform/ methanol (1:2), isolated by TLC, and quantitated as previously described (1,15). Protein was measured according to the method of Lowry et al (16) using BSA as a standard.…”

Section: Methodsmentioning

confidence: 99%

Ischemia-induced loss of epithelial polarity. Role of the tight junction.

Molitoris¹,

Falk²,

Dahl³

1989

J. Clin. Invest.

134

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In proximal tubular cells ischemia is known to result in the redistribution of apical and basolateral domain-specific lipids and proteins into the alternate surface membrane domain.Since tight junctions are required for the maintenance of surface membrane polarity, the effect of ischemia on tight junction functional integrity was investigated. In vivo microperfusion of early loops of proximal tubules with ruthenium red (0.2%) in glutaraldehyde (2%) was used to gain selective access to and outline the apical surface membrane. Under control situations ruthenium red penetrated < 10% of the tight junctions. After 5, 15, and 30 min of ischemia, however, there was a successive stepwise increase in tight junction penetration by ruthenium red to 29, 50, and 62%, respectively. This was associated with the rapid duration-dependent redistribution of basolateral membrane domain-specific lipids and NaK-ATPase into the apical membrane domain. Taken together, these data indicate that during ischemia proximal tubule tight junctions open, which in turn leads to the lateral intramembranous diffusion of membrane components into the alternate surface membrane domain.

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Section: Methodsmentioning

confidence: 99%

Ischemia-induced loss of epithelial polarity. Role of the tight junction.

Molitoris¹,

Falk²,

Dahl³

1989

J. Clin. Invest.

134

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“…Cholesterol transport on the other hand, which is thought to occur by a vesicular mechanism, was found to be relatively slow (halftime of 26.5 min at 25 ° C), very temperature dependent and blocked by energy poisons [9]. A study on lipid transport in epithelial cells has indicated that the very rapid transport of PC and PI is in agreement with spontaneous, possibly protein-mediated, phospholipid transport rather than a membrane flow mechanism [10]. It remains to be established whether phospholipid transfer proteins take part in this spontaneous transport of phospholipids.…”

Section: Introductionmentioning

confidence: 94%

On the relationship between the dual specificity of the bovine brain phosphatidylinositol transfer protein and membrane phosphatidylinositol levels

Paridon

Gadella

Somerharju

et al. 1987

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The phosphatidylinositol transfer protein from bovine brain has a remarkable specificity pattern with a distinct preference for phosphatidylinositol (PI) and a low affinity for phosphatidylcholine (PC). In this study we have determined the affinity of Pl-transfer protein for PI relative to that for PC by measuring the binding of the fluorescent pyrene-labeled analogs of these phospholipids. From competition binding experiments it was estimated that the transfer protein has a 16-fold higher affinity for PI than for PC. This relative affinity together with the relative abundance of PI and PC, determines what proportion of the protein contains PI (e.g. 65% of the Pl-transfer protein in the case of bovine brain). From measuring lipid transfer between donor vesicles consisting of equimolar amounts of PC and PI, and an excess of acceptor vesicles consisting of various ratios of PC and PI, we have observed that the relative rates of the Pl-transfer protein-mediated transfer of PI and PC varies between 5 and 20. Kinetic analysis has indicated that PI-transfer protein carrying a PI molecule has different kinetic properties than the Pl-transfer protein carrying a PC molecule. It will be discussed that because of the dual specificity, Pl-transfer protein is ideally suited for maintaining PI levels in intracellular membranes.

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“…Renal cortical apical (brush border membrane, BBM) and basolateral membranes (BLM) were isolated simultaneously from the same cortical homogenate and characterized enzymatically as described in detail elsewhere [30][31][32][33][34][35][36]. Briefly, the procedure entailed rapid decapsulization and removal of thin cortical slices in chilled buffer (300 mM mannitol, 5 mM ethyleneglycol-bis [/3-aminoethylether]-N, N'-tetraacetic acid, 18 mmol Tris [hydroxymethyl] aminomethane hydrochloride, 0.1 mM phenyl-methylsulfonyl fluoride) at pH 7.4.…”

Section: Preparation and Characterization Of Membrane Fractionsmentioning

confidence: 99%

“…Determinations were carried out on alkaline phosphatase, leucine aminopeptidase, and NaK-ATPase as previously reported from our laboratory [30][31][32][33][34][35][36].…”

Section: Preparation and Characterization Of Membrane Fractionsmentioning

confidence: 99%

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Characterization of ischemia-induced loss of epithelial polarity

et al. 1988

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Total renal ischemia for various time intervals (0-50 min) resulted in the rapid and duration-dependent redistribution of polarized membrane lipids and proteins in renal proximal tubule cells. Following only 15 min of ischemia, apical membrane enrichment of NaK-ATPase, normally a basolateral membrane (BLM) enzyme, had increased (1.6 +/- 0.6 vs. 2.9 +/- 1.2, P less than 0.01). In vivo histochemical localization of NaK-ATPase showed reaction product throughout the apical microvillar region. PTH-stimulatable adenylate cyclase, another BLM protein, was also found in ischemic but not control apical membrane fractions. One dimensional SDS-PAGE showed four bands, present in control BLM and ischemic apical membranes, which could not be found in control apical membrane fractions. Immunohistochemical localization of leucine aminopeptidase (LAP) showed the enzyme was limited to the apical domain in control cells. Following ischemic injury (50 min), LAP staining could be seen within the cell and along the BLM. Following 24 hr of reperfusion, the BLM distribution of LAP was further enhanced. With cellular recovery from ischemic injury (5 days), LAP was again only visualized in the apical membrane. Duration-dependent alterations in apical and BLM lipids were also observed. Apical sphingomyelin and phosphatidylserine and the cholesterol-to-phospholipid ratio decreased rapidly while apical phosphatidylcholine and phosphatidylinositol increased. Taken together, these results indicate renal ischemia causes rapid duration-dependent reversible loss of surface membrane polarity in proximal tubule cells.

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Maintenance of epithelial surface membrane lipid polarity: A role for differing phospholipid translocation rates

Cited by 10 publications

References 25 publications

Ischemia-induced loss of epithelial polarity. Role of the tight junction.

Ischemia-induced loss of epithelial polarity. Role of the tight junction.

On the relationship between the dual specificity of the bovine brain phosphatidylinositol transfer protein and membrane phosphatidylinositol levels

Characterization of ischemia-induced loss of epithelial polarity

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