Intracellular degradation of 125I-labelled asialo-glycoproteins in rat hepatocytes: Effect of leupeptin on subcellular distribution of asialo-fetuin

The pool of cellular chelatable iron (‘free iron’, ‘low-molecular-weight iron’, the ‘labile iron pool’) is usually considered to reside mainly within the cytosol. For the present study we adapted our previously established Phen Green method, based on quantitative laser scanning microscopy, to examine the subcellular distribution of chelatable iron in single intact cells for the first time. These measurements, performed in isolated rat hepatocytes and rat liver endothelial cells, showed considerable concentrations of chelatable iron, not only in the cytosol but also in several other subcellular compartments. In isolated rat hepatocytes we determined a chelatable iron concentration of 5.8±2.6μM within the cytosol and of at least 4.8μM in mitochondria. The hepatocellular nucleus contained chelatable iron at the surprisingly high concentration of 6.6±2.9μM. In rat liver endothelial cells, the concentration of chelatable iron within all these compartments was even higher (cytosol, 7.3±2.6μM; nucleus, 11.8±3.9μM; mitochondria, 9.2±2.7μM); in addition, chelatable iron (approx. 16±4μM) was detected in a small subpopulation of the endosomal/lysosomal apparatus. Hence there is an uneven distribution of subcellular chelatable iron, a fact that is important to consider for (patho)physiological processes and that also has implications for the use of iron chelators to inhibit oxidative stress.

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Pseudocolor image processing of PEPCK subcellular distribution in rat hepatocytes shown with IGSS and epipolarization microscopy.

Journal of Histochemistry & Cytochemistry ◽

10.1177/42.12.7983366 ◽

1994 ◽

Vol 42 (12) ◽

pp. 1651-1653 ◽

Cited By ~ 4

Author(s):

K Gao ◽

E L Cardell

Keyword(s):

Image Processing ◽

Subcellular Distribution ◽

Rat Hepatocytes

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CELLULAR CATABOLISM OF RECOMBINANT TISSUE-TYPE PLASMINOGEN ACTIVATOR: IDENTIFICATION AND CHARACTERIZATION OF A NOVEL HIGH AFFINITY UPTAKE SYSTEM ON RAT HEPATOCYTES

10.1055/s-0038-1644400 ◽

1987 ◽

Author(s):

C Bakhit ◽

D Lewis ◽

R Billings ◽

B Malfroy

Keyword(s):

Rat Hepatocytes ◽

Tissue Type ◽

Scatchard Analysis ◽

Uptake System ◽

Isolated Rat Hepatocytes ◽

Intracellular Degradation ◽

High Affinity ◽

Type Plasminogen Activator ◽

Identification And Characterization

The uptake, internalization and intracellular degradation of 125I-labeled rt-PA (125I-rt-PA) by isolated rat hepatocytes was investigated. Incubation at 37°C resulted in internalization of 125I-rt-PA, followed by the appearance of labeled trichloroacetic acid-soluble (TCA) material in the inclubation media due to degradation of rt-PA. Degradation of rt-PA was inhibited by the presence of NH4Cl (10mM) or chloroquine (ImM) (lysosoma tropic agents) in the incubation media. This suggests that rt-PA degradation occurs intracellularly, perhaps within the lysosomes. 125I-rt-PA was taken up by rat hepatocytes through a specific, high affinity mechanism. Scatchard analysis of the data indicated that 106 molecules of rt-PA were taken up per cell/hour and the calculated dissociation constant was lOnM. Uptake of 125I-rt-PA was not inhibited by glycopeptides isolated from rt-PA nor by several other glycoproteins known to be cleared by identified hepatic receptors. These results suggest that the uptake of rt-PA by rat hepatocytes involves a receptor specific for t-PA and is not mediated by a carbohydrate specific receptor.

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Subcellular distribution of lead in cultured rat hepatocytes

Environmental Research ◽

10.1016/0013-9351(84)90126-9 ◽

1984 ◽

Vol 35 (1) ◽

pp. 188-196 ◽

Cited By ~ 6

Author(s):

Roberta A. Mittelstaedt ◽

Joel G. Pounds

Keyword(s):

Subcellular Distribution ◽

Rat Hepatocytes ◽

Cultured Rat Hepatocytes

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