Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Filipin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1977

Effect of the polyene antibiotic filipin on the permeability of the inward- and the outward-facing membranes of the isolated from skin (Rana temporaria).

The effect of the polyene antibiotic filipin on the electrical properties and the passive permeability of the cell membranes was investigated. The addition of filipin to the outside bathing solution has the following effects: 1. it results in a drastic reduction in the transepithelial resistance and potential, 2. it causes a 10-20 times increase in the passive transepithelial chloride, sodium and sucrose flux, 3. it results in the formation of an amiloride insensitive sodium pathway in the outward facing membrane, 4. it results in an active outward transport of potassium, 5. it results in a highly significant swelling of all the cells in the epithelium. The addition of filipin to the inside bathing solution has the following effects 1. it results in an activation of the active sodium transport, 2. it causes a slight increase in the passive transepithelial chloride and sodium permeabilities but has no effect on the sucrose permeability, 3. it has no effect on the amiloride inhibition of the short-circuit current, 4. it has no effect on the volume of the cells in the epithelium. It is suggested that the addition of filipin to the outside bathing solution increases the direct sodium flow from cell to cell in neighbour layers. Furthermore these experiments indicate that the outward facing membrane of the isolated frog skin has a high cholesterol content as compared with the cholesterol content of the inward facing membrane.

Amiloride↗
PubMed1974

Molecular basis for the selective toxicity of amphotericin B for yeast and filipin for animal cells.

Among the polyene antibiotics, many, like filipin, cannot be used clinically because they are toxic; amphotericin B, however, is useful in therapy of human fungal infections because it is less toxic. Both the toxicity of filipin and the therapeutic value of amphotericin B can be rationalized at the cellular and molecular level by the following observations: (i) these polyene antibiotics showed differential effects on cells; filipin was more potent in lysing human red blood cells, whereas amphotericin B was more potent in inhibiting yeast cell growth; and (ii) the effects of filipin were more efficiently inhibited by added cholesterol, the major membrane sterol in human cells, whereas the effects of amphotericin B were more efficiently inhibited by ergosterol, the major membrane sterol in yeast. The simplest inference is that the toxicity and effectiveness of polyenes are determined by their relative avidities for the predominant sterol in cell membranes.

Amphotericin B↗
PubMedDate not supplied

Transendothelial transport of low-density lipoprotein and albumin across the rat peritoneum in vivo: effects of the transcytosis inhibitors NEM and filipin.

This study was performed to investigate the mechanisms responsible for the transport of albumin and low-density lipoprotein (LDL) across capillary walls in vivo. To separate transcytosis from passive, 'porous' transport, we tested the effects of the transcytosis inhibitors N-ethylmaleimide (NEM) and filipin given intraperitoneally on the peritoneal capillary clearance of LDL and albumin in anesthetized rats undergoing peritoneal dialysis. Radiolabeled human albumin or LDL was given intra-arterially, and (51)Cr-EDTA was infused intravenously. A 2-hour peritoneal dialysis dwell was performed using 16 ml of conventional 1.36% glucose-based dialysis fluid. The clearance of LDL and albumin to the dialysate and the peritoneal mass transfer coefficient for (51)Cr-EDTA were assessed. Following intraperitoneal NEM incubations (0.5-5 mM), there were marked increases in the peritoneal transport of albumin and LDL for NEM doses exceeding 1 mM. For lower NEM doses, there were no reductions in clearance. Filipin incubations (0.2-4 microg/ml) did not affect the clearance of either macromolecule. In conclusion, neither NEM nor filipin caused reductions in albumin or LDL clearance across the peritoneal capillaries. The present data clearly show that NEM and filipin are unsuitable as transcytosis inhibitors in vivo.

Albumins↗
PubMed1994

Filipin vs enzymatic localization of cholesterol in guinea pig, mink, and mallard duck testicular cells.

To test the validity of filipin cytochemistry for localization of cholesterol in testicular cells, we compared the results obtained by this technique with those obtained by a two-step enzymatic method involving cholesterol esterase and cholesterol oxidase. In all the animals models tested (guinea pig, mink, and mallard duck) the disappearance of subsurface filaments along Sertoli cell junctional membranes was accompanied by a significant increase in the number of filipin-cholesterol complexes/microns 2 in these membranes. Enzyme histochemistry allowed localization of free cholesterol in the limiting membrane of multivesicular bodies, in membranes within lysosomes, in mitochondrial membranes, and in junctional membranes, with or without subsurface filaments. The method also permitted selective visualization of cholesterol esters in lipid droplets. We conclude that filipin mapping of cholesterol induces false-negative cytochemical results. The enzymatic method is superior to filipin because it allows localization of free cholesterol in junctional membranes and of cholesterol esters in lipid droplets. This compartmentalization of the compounds may represent the basis of a system that helps to maintain constant free cholesterol levels in the testis.

3,3'-Diaminobenzidine↗
PubMed1986

[Effect of filipin, a polyene antibiotic, on human tumor cell killing in vitro by peplomycin].

Four kinds of cultured human tumor cell lines sensitive or resistant to bleomycin (BLM) were examined for the effect of filipin, a polyene antibiotic, on peplomycin (PEP)-induced cell killing. Although PEP was more effective than BLM against BLM-resistant HeLa cells (HeLa-BLMr), neoplastic cells derived from salivary gland (HSG) and melanoma cells (MEC), these three cell lines were still at least ten times more resistant to PEP than epidermoid carcinoma cell lines including HeLa cells by comparison of IC50, and showed lower cellular accumulation of 3H-PEP as compared with HeLa cells. When these lines were pretreated with filipin, 3H-PEP accumulation by the cells was increased 1.33-, 2.34-, 1.91- and 1.14-fold in HeLa, HeLa-BLMr, HSG and MEC cells, respectively. Combination use of PEP and filipin resulted in a remarkable enhancement of cytocidal effect in HeLa-BLMr and HSG cells (100- and 25-fold decrease of IC50, respectively), and a slight enhancement in HeLa cells, but not in MEC cells. It is therefore suggested that there are differences among cell types in the potentiation of PEP-induced cell killing by filipin.

Bleomycin↗
PubMed1984

Localization of filipin-sterol complexes in cell membranes of eosinophils.

The polyene antibiotic filipin was used as a probe for the detection of cholesterol in the cell membranes of eosinophils isolated from the peritoneal exudate of rats. A homogenous distribution of filipin-sterol complexes was observed, both in thin sections and freeze-fracture replicas throughout the whole plasma membrane but not in the membrane of pynocytic vesicles, Golgi complex, endoplasmic reticulum, mitochondria and the nucleus. Few complexes were seen in freeze-fracture replicas showing the membrane of the specific granules. Treatment of living cells with filipin induced aggregation of filipin-sterol complexes at some points of the plasma membrane.

Animals↗
PubMed1984

Distribution of filipin-sterol complexes in rat hepatocytes.

Distribution of cholesterol in rat hepatocytes under normal untreated and phenobarbital-treated conditions was studied by freeze-fracturing using filipin. In untreated rat hepatocytes, filipin-sterol complexes were observed on intercellular plasma membranes as well as on lysosomes and microbodies. These complexes were evenly distributed. In phenobarbital-treated rat hepatocytes, filipin-sterol complexes in the lysosomes or microbodies were distributed unevenly. In the bile canaliculi, no filipin-sterol complexes were noted. Based on these findings, the functional state of the organellae concerned was discussed.

Alkaline Phosphatase↗
PubMed1984

Distribution of filipin-cholesterol complexes in rat incisor odontoblasts.

Using the polyene antibiotic filipin as a probe to visualize cholesterol on freeze-fracture replicas of membranes of young odontoblasts of rat incisor, we demonstrated that cholesterol-rich domains were present in cell processes, whereas only a small number of deformations induced by cholesterol-filipin interaction was observed in cell bodies. Except for a few large vesicles, intracellular membranes did not react with filipin. The large number of intramembrane particles observed on the plasma membrane of odontoblast processes did not affect the formation of visible filipin-cholesterol complexes.

Animals↗
PubMed1984

Distribution of filipin-sterol complexes in villus goblet cell membranes of rat small intestine.

The polyene antibiotic, filipin, was used as a morphologic probe to determine the distribution of cholesterol in plasma and intracellular membranes in freeze fracture replicas of villus goblet cells from rat small intestine. Endoplasmic reticular and cis-face Golgi membranes displayed only rare filipin-sterol complexes. Membranes of the Golgi trans-face and adjacent nascent secretory granules revealed a moderate number of complexes. Membranes of mature secretory granules contained numerous filipin-sterol complexes, especially in sites where adjacent granules abutted. Complexes were so abundant on the apical plasma membrane that they approached confluence. The areal density of filipin-sterol complexes on the lateral plasma membrane was less than on the apical membrane but varied from goblet cell to goblet cell. The number of complexes on the lateral membrane of cells that appeared to be actively secreting mucus at the time of fixation was greater than on cells that showed no evidence of active mucus secretion. Thus, in villus goblet cells of rat small intestine (a) mucous granule membranes and the apical plasma membrane with which they fuse during secretion appear strikingly enriched with cholesterol, (b) cholesterol appears to be incorporated into mucous granule membranes during and shortly after their formation at the Golgi trans-face, and (c) the cholesterol content of the lateral plasma membrane of secreting goblet cells appears to be greater than that of nonsecreting cells.

Animals↗
PubMed1983

Asymmetric distribution and temperature-dependent clustering of filipin-sterol complexes in the nuclear membrane of Ehrlich ascites tumor cells.

When Ehrlich ascites tumor (EAT) cells were fixed at 4 degrees C and freeze-fractured, patchy areas having no intramembrane particles were visible in the nuclear envelope. The particle free areas (PFAs) were not seen on fixation at 28 degrees C, indicating that appearance of PFAs was caused by a kind of thermotropic phase separation. The PFAs were detected only in the nuclear membrane, and not in the plasma membrane. Most of them were present in the outer membrane of the nuclear envelope. In cells fixed at 4 degrees C, and treated with filipin all the filipin-sterol complexes appeared in clusters located in the PFAs. In contrast, the filipin-sterol complexes were evenly distributed in cells fixed at 28 degrees C. This suggests that at low temperature, molecules of cholesterol gather in the PFAs. Temperature-dependent cluster formation was seen only in the complexes of the nuclear membrane, suggesting that the cholesterol in the nuclear membrane is more mobile than that in the plasma membrane. In addition, the distribution of filipin-sterol complexes in the nuclear envelope was asymmetric. The complexes were seen only in the outer (cytoplasmic), but not in the inner (nucleoplasmic) membrane of the nuclear envelope, reflecting differences in the structural, and presumably functional, characteristics of the outer and inner nuclear membranes.

Animals↗
PubMed1982

Isolation and characterization of filipin-resistant LM cell variants not auxotrophic for sterol.

A series of LM cell variants resistant to filipin, but not auxotrophic for sterol, was isolated by plating mutagenized, filipin-treated cells on soft agar medium containing no sterol. Cloned variants were assayed for growth in the presence and absence of sterol or unsaturated fatty acid. Filipin-resistant clones whose growth rate was unaffected by the addition of sterol to the medium were further analyzed. Variants were cultured in minimal medium, and plasma membranes prepared from these cultures were analyzed for sterol content, phospholipid head group composition, and unsaturated fatty acyl content. All variants examined showed a decrease in membrane sterol in conjunction with an increase in unsaturated fatty acyl chains in the membrane phospholipids. In addition, several variants exhibited alterations in phospholipid head group composition, including changes in the phosphatidylcholine/phosphatidylethanolamine ratio, or a decrease in sphingomyelin content. These observations imply that several different metabolic lesions can give rise to decreased plasma membrane sterol content (and hence to filipin resistance). The range of phospholipid alterations observed in these sterol prototrophs emphasizes the complex interrelationship between membrane sterol and phospholipid structure.

Animals↗
PubMed1982

Comparison of the response of myocardial muscle and capillary endothelial nuclear membranes to the cholesterol probe filipin.

The polyene antibiotic filipin was used as a probe for cholesterol in the nuclear membranes of cardiac muscle and capillary endothelial cells. Samples of perfusion-fixed rabbit and rat myocardium were exposed to filipin in glutaraldehyde fixative, prior to examination by standard freeze-fracture techniques. Quantitative analysis of the responses of the inner and the outer nuclear membranes of the two cell types was carried out by measuring the numerical density of filipin-induced lesions in each. Cardiac muscle cell outer nuclear membranes displayed few or no lesions (less than 0.1 micron-2), and their inner nuclear membranes were completely resistant to the treatment. By contrast, a marked response to filipin was found in the endothelial nuclear envelope, the outer membrane showing an average of 250 lesions micron-2, and the inner membrane 63 lesions micron-2. These results are interpreted as a direct reflection of differences in cholesterol content between the outer and inner nuclear membranes of the two cell types. The significance of the apparent differences in cholesterol content demonstrated between the nuclear envelopes of different cell types is discussed with reference to biochemical data, plasma membrane cholesterol content, nuclear membrane function and the supply of exogenous cholesterol.

Animals↗
PubMed1981

Plasma membrane cholesterol in myocardial muscle and capillary endothelial cells. Distribution of filipin-induced deformations in freeze-fracture.

Glutaraldehyde-fixed rabbit myocardium was treated with the polyene antibiotic, filipin, which binds specifically to sterols in membranes, producing distinct 25 nm-diameter deformations. These deformations (lesions) serve as labels for the presence of cholesterol-rich membranes and membrane domains. The distribution and density of filipin-induced lesions was examined in the plasma membranes of cardiac muscle and capillary endothelial cells by freeze-fracture electron microscopy. In the exposed fracture faces of endothelial plasma membranes, more than 99% of the surface area was covered with lesions, whereas about 90% of the plasma membrane area in the muscle cells remained unaffected by the treatment. Muscle cell plasma membranes revealed a patchy response; the lesions occurred in clusters which were separated by interconnecting expanses of unaffected membrane. Endothelial cell plasmalemmal vesicles, and muscle cell caveolae and transverse tubules displayed the same response to filipin as neighbouring areas of plasma membrane. However, gap junctions and desmosomes of the muscle intercalated disc membrane, and coated pits in both cell types were completely resistant to filipin treatment. These results provide evidence that the plasma membranes of the two cell types possess markedly different overall cholesterol levels, and that each has a characteristic pattern in the planar distribution of cholesterol.

Animals↗
PubMed1987

A critical evaluation of the use of filipin-permeabilized rat hepatocytes to study functions of the endoplasmic reticulum in situ.

We have used transmission (TEM) and scanning electron microscopy (SEM) and leakage of lactate dehydrogenase (LDH; EC 1.1.1.27) to evaluate two published procedures which use filipin to render isolated rat hepatocytes permeable to ionic substrates. Cells treated by the procedure of Jorgenson and Nordlie retained less than 10 per cent of their LDH. TEM revealed severe damage to the internal structure of these cells, which included swelling, disintegration and extensive vesicularization of the endoplasmic reticulum (ER). Hepatocytes treated with filipin by the procedure of Gankema et al. retained 65-75 per cent of their LDH and displayed incomplete but highly variable permeability to Trypan blue. SEM revealed the loss of microvilli, other signs of swelling, and the presence of large lesions in the plasma membrane. TEM revealed signs of cell swelling, but the nuclei and the mitochondria were only moderately altered. The rough ER was not swollen, but significant fragmentation was evident and characteristic stacks of lamellar ER were never seen. We conclude that useful information about the functions of the ER in situ cannot be obtained from studies of filipin-treated cells. Our results indicate that retention of LDH is not a sufficient criterion of preservation of cell morphology and that staining with Trypan blue may significantly underestimate the permeability of cells to small ionic metabolites.

Animals↗
PubMed1989

Changes in the distribution of intramembranous particles and filipin-reactive membrane sterols during in vitro capacitation of golden hamster spermatozoa.

Membrane alterations accompanying in vitro capacitation of hamster spermatozoa were examined using the freeze-fracture technique with or without use of filipin, a sterol-binding probe. In the spermatozoa prior to or at 10 min after start of incubation in capacitating medium, large (about 11 nm) and small (8-9 nm) intramembranous particles (IMPs) were present in the periacrosomal region of the sperm plasma membrane (PAPM). Filipin sterol complexes (FSCs) were densely (about 500/micron 2) distributed in the PAPM prior to incubation. The density of FSCs in the PAPM was reduced by 70-80% of the original density by 2 hr of incubation. At the same time, small patches of IMP-free areas appeared in the plasma membrane above the equatorial and middle segments of the acrosome. By the end of 3 hr of incubation, the majority of small IMPs had disappeared from the PAPM. Remaining large and small IMPs tended to aggregate in the PAPM. During incubation in capacitation medium, "cords," or linear arrangements of closely packed IMPs, appeared near the posterior ring of the sperm head. These observations strongly suggest that the acrosome reaction of the hamster spermatozoa is preceded by the removal (deletion) of filipin-reactive sterols (FRSs) and the disappearance of small IMPs from the lipid bilayer of PAPM.

Acrosome↗
PubMed1983

Regional difference in effect of filipin in plasma membranes of epithelial cells and surrounding free cells in the choroid plexus.

Epithelial cells and surrounding free cells in the choroid plexus were examined cytochemically using filipin to clarify the distribution pattern of cholesterol within plasma membranes. The apical and basal membranes of the choroid epithelial cell are less susceptible to filipin than the lateral epithelial membrane and plasma membranes of adjacent mesenchymal cells such as macrophages and fibroblasts. Apical and basal domains of the epithelial membranes, which are relatively resistant to action of filipin, appear to have a slightly lower cholesterol content. We suggest that the apical and basal membranes may possess a unique membrane fluidity or stability that differs from that of the lateral epithelial, macrophage or fibroblast membranes.

Animals↗
PubMed1982

Further freeze-fracture studies on the uterine epithelium of Salamandra salamandra (L.) (Amphibia, Urodela) using the antibiotic filipin.

The apical portion of the uterine lining of the ovoviviparous fire salamander, Salamandra salamandra, was studied by the freeze-fracture technique in conjunction with the polyene antibiotic filipin. Filipin-sterol complexes were found in the luminal plasmalemma and in the membranes limiting the mucous secretory granules typical of this epithelium. In all females, but particularly in non-pregnant females, more or less discrete clusters of filipin-sterol complexes were occasionally found overlying heavily affected secretory granules. The findings are discussed with regard to comparable results (Orci et al. 1980) based on the examination of collapsed and stretched urinary bladders of toads.

Animals↗
PubMed1989

Intramembrane particles and filipin labelling on the membranes of autophagic vacuoles and lysosomes in mouse liver.

Morphologically detectable protein (intramembrane particles) and cholesterol (filipin labelling) in the membranes of autophagic vacuoles and lysosomes were studied in mouse hepatocytes using thin-section and freeze-fracture electron microscopy. Both isolated autophagic vacuoles and lysosomes, and intact tissue blocks were used due to the facts (i) that lysosomes are difficult to recognize in freeze-fracture replicas of intact hepatocytes, and (i) that filipin penetration into the tissue blocks is unsatisfactory. Intramembrane particle density was low in the membranes of early autophagic vacuoles (defined as round-shaped vacuoles in which an inner membrane parallel with the outer limiting membrane was clearly visible). The lysosomal membranes contained considerably more intramembrane particles. Particle-rich lysosomes or other vesicles were observed to fuse with the early autophagic vacuoles. The membranes of nascent autophagic vacuoles with morphologically intact contents were usually not labelled by filipin, whereas the membranes of all other autophagic vacuoles and lysosomes were heavily labelled. The increased cholesterol in the membranes of slightly older autophagic vacuoles is presumably derived from cholesterol-rich lysosomes or other vesicles fusing with the vacuoles and from the degrading organelles inside the autophagic vacuoles.

Animals↗