engleski

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

In the mammmalian cells, recycling of various membrane components between the plasma membrane and intracellular organelles via vesicle trafficking mechanism depends on intact microtubules (MT). In the rat proximal tubule cells, MT are arranged in bundles that seem to be denser in the cells from the proximal tubule straight segment (PST)than in the cells from the proximal tubule convoluted segment (PCT).In this work we injected rats with a single dose of colchicine (0.35 mg/100 g B.M., i.p., 12 h before sacrifice) or phopsphate-buffered saline (controls), and studied the intracellualr distribution of MT and several brush-border proteins, such as megalin (gp330), vacuolar H+-ATPase (V-ATPase), sodium phosphate cotransporter type 2 (NaPi-2), and water channel aquaporin-1 (AQP-1) in the PCT and PST cells. As found by Western blotting of proteins from the tissue homogenates and by indirect immunofluorescence cytochemistry in 4um thick cryosections of the frozen fixed tissues, colchicine treatment resulted in a significant loss of a-tubulin in the outer cortex and inner stripe tissues and disappearance of MT in the PCT and PST cells, respectively. Immunocytochemical studies also revealed a marked loss of gp 330, NaPi-2 and 31 kD V-ATPase subunit antigens from the BBM and their redistribution in intracellular vesicles in both PCT and PST cells. The sam pattern was observed for distribution of AQP-1 in the PCT cells. However, in the PST cells, the staining intensitiy with the anti-AQP-1 antibody in BBM remained unaffected, and the redistribution of this antigen in intracellular vesiclesdid not occur in colchicine-treated rats. We conclude that in PST cells 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 PCT cells.

microtubules; membrane recycling; water channels; kidney; rat

nije evidentirano