The permeability of lysosomes to sugars. Effect of diethylstilbestrol on the osmotic activation of lysosomes induced by glucose

We have investigated the effect on the osmotic activation of rat liver lysosomes, by glucose penetration, of different substances known to inhibit the glucose transport through the plasma membrane. Diethylstilbestrol is the most efficient, particularly when purified lysosomes are used. It has no effect on osmotic activation induced by hypo-osmotic sucrose or by iso-osmotic KCl. It is proposed that diethylstilbestrol reacts with specific sites involved in the glucose translocation through the lysosomal membrane. These sites could not be identified by binding experiments, presumably owing to the considerable unspecific binding of the compound to the membrane.

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Genistein inhibits glucose and sulphate transport in isolated rat liver lysosomes

British Journal Of Nutrition ◽

10.1017/s0007114509991693 ◽

2009 ◽

Vol 103 (2) ◽

pp. 197-205 ◽

Cited By ~ 3

Author(s):

Hsu-Fang Chou ◽

Kun-Hung Chuang ◽

Yi-Shan Tsai ◽

Yi-Ju Chen

Keyword(s):

Glucose Uptake ◽

Glucose Transport ◽

Rat Liver ◽

Uptake Kinetics ◽

Isolated Rat Liver ◽

Sulphate Transport ◽

Genistein Treatment ◽

Liver Lysosomes ◽

Rat Liver Lysosomes ◽

Isolated Rat

Genistein and daidzein are known to have both beneficial and adverse effects on human health due to their many biological actions at the cellular level. Both isoflavones have been shown to inhibit GLUT-mediated glucose transport across the plasma membrane of mammalian cells. Since lysosomal membrane transport is essential for maintaining cellular homeostasis, the present study examined the effects of genistein and daidzein on glucose and sulphate transport in isolated rat liver lysosomes. Both genistein and daidzein significantly inhibited lysosomal glucose uptake. Genistein was a more potent glucose transport inhibitor than daidzein, with a half-maximum inhibitory concentration (IC50) of 45 μmol/l compared with 71 μmol/l for daidzein. Uptake kinetics of d-glucose showed a significant decrease in Vmax (control:genistein treat = 1489 (sem 91):507 (sem 76) pmol/unit of β-hexosaminidase per 15 s) without a change in Km. The presence of 50 μm-genistein in the medium also reduced glucose efflux from lysosomes preloaded with 100 mm-d-glucose. Genistein also inhibited lysosomal sulphate transport. Similar to its effects on glucose uptake kinetics, genistein treatment caused a significant decrease in sulphate uptake Vmax (control:genistein treat = 87 (sem 4):59 (sem 5) pmol/unit of β-hexosaminidase per 30 s), while the Km was not affected. The evidence provided by the present study suggests that the most likely mechanism of lysosomal glucose transport inhibition by genistein is via direct interaction between genistein and the transporter, rather than mediation by tyrosine kinase inactivation. Genistein likely has a similar mechanism of directly inhibiting sulphate transporter.

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Effect of Glycyrrhizin on Lysosomes Labilization by Phospholipase A2

The American Journal of Chinese Medicine ◽

10.1142/s0192415x86000211 ◽

1986 ◽

Vol 14 (03n04) ◽

pp. 131-137 ◽

Cited By ~ 8

Author(s):

Yasuko Shiki ◽

Yo Ishikawa ◽

Kohji Shirai ◽

Yasushi Saito ◽

Sho Yoshida

Keyword(s):

Acid Phosphatase ◽

Phospholipase A2 ◽

Rat Liver ◽

Lysosomal Membrane ◽

Phospholipase A ◽

Ph Optimum ◽

Liver Lysosomes ◽

Inhibited Acid ◽

Rat Liver Lysosomes

The influence of glycyrrhizin on the effect of phospholipase A2 on lysosomes was studied. Treatment of rat liver lysosomes with venom phospholipase A2 caused release of acid phosphatase. This release of acid phosphatase was inhibited by 0.1 mM glycyrrhizin. Glycyrrhizin also inhibited acid phospholiase A2 with pH optimum of 4.5, which is thought to be present in the lysosomal membrane. These results suggests that glycyrrhizin stabilizes lysosomes by inhibiting phospholipase A2 activity in the lysosomal membrane.

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Isolation of rat liver lysosomes by isopycnic centrifugation in a metrizamide gradient.

The Journal of Cell Biology ◽

10.1083/jcb.78.2.349 ◽

1978 ◽

Vol 78 (2) ◽

pp. 349-368 ◽

Cited By ~ 254

Author(s):

R Wattiaux ◽

S Wattiaux-De Coninck ◽

M F Ronveaux-dupal ◽

F Dubois

Keyword(s):

Enzyme Activity ◽

Plasma Membrane ◽

Rat Liver ◽

Specific Activity ◽

Mitochondrial Fraction ◽

Marker Enzyme ◽

Marker Enzymes ◽

Liver Lysosomes ◽

Rat Liver Lysosomes ◽

Isopycnic Centrifugation

A preparation, similar to the light mitochondrial fraction of rat liver (L fraction of de Duve et al, (1955, Biochem. J. 60: 604-617), was subfractionated by isopycnic centrifugation in a metrizamide gradient and the distribution of several marker enzymes was established. The granules were layered at the top or bottom of the gradient. In both cases, as ascertained by the enzyme distributions, the lysosomes are well separated from the peroxisomes. A good separation from mitochondria is obtained only when the L fraction if set down underneath the gradient. Taking into account the analytical centrifugation results, a procedure was devised to purify lysosomes from several grams of liver by centrifugation of an L fraction in a discontinuous metrizamide gradient. By this method, a fraction containing 10--12% of the whole liver lysosomes can be prepared. As inferred from the relative specific activity of marker enzymes, it can be estimated that lysosomes are purified between 66 and 80 times in this fraction. As ascertained by plasma membrane marker enzyme activity, the main contaminant could be the plasma membrane components. However, cytochemical tests for 5'AMPase and for acid phosphatase suggest that a large part of the plasma membrane marker enzyme activity present in the purified lysosome preparation could be associated with the lysosomal membrane. The procedure for the isolation of rat liver lysosomes described in this paper is compared with the already existing methods.

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