Differential distribution of actin and cytokeratin in isolated full-length rabbit renal tubules.
The distribution of basal actin bundles and cytokeratin intermediate filaments in the rabbit kidney was examined along isolated renal tubules by confocal laser microscopy. Perfusion of collagenase and subsequent manipulation of kidney tissues yielded well preserved renal tubules free of connective tissue components often extending from glomeruli to collecting tubules. Such isolated renal tubules were fluorescently stained with phalloidin and with anti-cytokeratin antibody and then observed as whole-mount preparations by confocal laser microscopy. Epithelial cells of Bowman's capsules showed conspicuous actin bundles which were arranged parallel to each other in individual cells. In proximal ducts, thick actin bundles were seen running in the basal regions of epithelial cells perpendicular to the tubule axis. Basal actin bundles in proximal tubules appeared to be somewhat thinner and run more irregularly in more distal parts of the tubule. Thin limbs of Henle's loop showed bright but very short rod or dot-like stainings of actin, while in thick limbs, there were thick and short actin bundles. In distal tubules basal actin bundles were somewhat longer than those in thick limbs of Henle's loop. In the collecting ducts in the renal cortex, a few short actin bundles as well as dotty or patchy stainings were shown in the basal region. In both whole-mount preparations and cryostat sections, cytokeratin immunoreactivities were almost exclusively detected in epithelial cells of Henle's loops and collecting ducts but poorly in proximal and distal tubules. Epithelial cells of Henle's loops showed dense networks of cytokeratin immunoreactivities throughout the cytoplasm, whereas cell boundaries were immunostained in collecting ducts. The actin and cytokeratin distribution in such isolated renal tubules was confirmed by immunofluorescence of cryostat sections and by thin-section electron microscopy. The observations that actin and intermediate filaments varied in distribution in different segments of renal tubules are interesting in view of the segmental differentiation of renal tubule functions.
Department of Anatomy, Gunma University School of Medicine, Japan.
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K
Goto
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Ishikawa
D000199:Actins / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D007633:Keratins / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism / Q000648:ultrastructure; D007684:Kidney Tubules / Q000378:metabolism* / Q000648:ultrastructure; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D011817:Rabbits
D000199:Actins; D007633:Keratins