Hyperglycemia induced down-regulation of renal P-glycoprotein expression.
The purpose of this study is to investigate the regulation of P-glycoprotein expression in the kidney under diabetic condition. Renal P-glycoprotein expression was examined in inbred mice with type 1 or type 2 diabetes by Western blotting. The underlying mechanisms of P-glycoprotein regulation were examined in Madin-Darby canine kidney type II (MDCK-II) cells by Western blotting or qRT-PCR. (3)H-digoxin uptake was measured for P-glycoprotein activity in cells under various treatments. The results showed that P-glycoprotein expression was lower in kidneys of diabetic mice than in controls. In MDCK-II cells, treatments with insulin or IL-6 did not cause any change in P-glycoprotein expression, whereas TNF-α tended to increase P-glycoprotein expression at a concentration of 1 ng/ml. On the other hand, P-glycoprotein expression was reduced under high glucose conditions (450 mg/dl), while superoxide production was increased, and the reduction in P-glycoprotein expression was abolished by N-acetylcysteine (an antioxidant) and staurosporine (a nonselective PKC inhibitor). Treatment with oxidizing agents (H(2)O(2), BSO) or PMA (a PKC activator) reduced P-glycoprotein expression. Antioxidant (N-acetylcysteine or glutathione) co-treatment abolished the H(2)O(2)-induced and BSO-induced reduction in P-glycoprotein expression, whereas it did not prevent the effect of PMA. The PMA-induced P-glycoprotein down-regulation was prevented by co-treatment of LY333531 (a PKC-β inhibitor). (3)H-digoxin levels were higher in MDCK-II cells with high glucose, PMA or H(2)O(2) treatments. In conclusion, P-glycoprotein expression is lower in kidneys of diabetic mice and in MDCK-II cells under high glucose conditions. Hyperglycemia induced reactive oxygen species and activated PKC in MDCK-II cells, leading to the decrease in P-glycoprotein expression.
School of Pharmacy, College of Medicine, National Taiwan University, 1 Jen-Ai Road, Section 1, Taipei 100, Taiwan.
Szu-Yu
SY
Yeh
Huei-Ju
HJ
Pan
Chung-Cheng
CC
Lin
Yu-Han
YH
Kao
Yen-Hui
YH
Chen
Chun-Jung
CJ
Lin
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D048909:Diabetes Complications / Q000097:blood / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D004077:Digoxin / Q000378:metabolism; D004285:Dogs; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D006943:Hyperglycemia / Q000097:blood / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D007328:Insulin / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D051379:Mice; D011493:Protein Kinase C / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001786:Blood Glucose; D007328:Insulin; D015850:Interleukin-6; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D004077:Digoxin; D011493:Protein Kinase C