engleski

In colchicine-treated rats, cellular distribution of AQP-1 in convoluted and straight proximal tubule segments is differently affected

In cells along the nephron, the recycling of various components between the plasma membrane and intracellular organelles via vesicle trafficking depends on intact microtubules (MT). Previous studies in rats treated with MT disrupting drug colchicine showed that some brush-border membrane (BBM) transporters in the renal proximal convoluted tubule cells (PCTC) become internalized in numerous vesicles randomly scattered in the cytoplasm. In this work, we compared the intracellular distribution of MT and several BBM proteins (megalin, vacuolar (V)-ATPase, water channel aquaporin-1 (AQP-1)) as well as endocytosis of the in vivo injected fluorescent marker (FITC-dextran) in the PCTC and proximal straight tubule cells (PSTC) in control and colchicine-treated rats. The immunoblotting and immunocytochemical data showed that colchicine treatment caused in the PCTC and PSTC: a) disappearance of MT, b) strongly diminished endocytosis of FITC-dextran, and c) marked loss of megalin and V-ATPase from the BBM and their redistribution in intracellular vesicles. Similar pattern was observed for the distribution of AQP-1 in the PCTC. However, in the PSTC, the staining intensity of AQP-1 in the BBM, as well as its intracellular distribution remained unaffected by colchicine treatment. We conclude that in the PSTC either MT play minor role in recycling of AQP-1 between the BBM and intracellular vesicles or the BBM AQP-1 turns over much slower than in the PCTC.

colchicine ; endocytosis ; gp330 ; kidney ; microtubules ; vacuolar ATPase ; water channels

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