Cell Biology – Immunology – Pathology
Kidney International (2000) 57, 2386–2402; doi:10.1046/j.1523-1755.2000.00098.x
Tight junction proteins ZO-1, ZO-2, and occludin along isolated renal tubules1
Lorenza Gonzalez-Mariscal, Maria C Namorado, Dolores Martin, Jose Luna, Lourdes Alarcon, Socorro Islas, Laura Valencia, Pablo Muriel, Lissette Ponce and Jose L Reyes
Department of Physiology, Biophysics and Neurosciences, and Department of Pharmacology, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico
Correspondence: Lorenza Gonzalez-Mariscal, Ph.D., Department of Physiology, Biophysics and Neuroscience, CINVESTAV, Apartado Postal 14-740, Mexico, D. F. 07000, Mexico. E-mail: lorenza@fisio.cinvestav.mx
1See Editorial by Brown, p. 2652
Received 11 February 1999; Revised 11 December 1999; Accepted 11 January 2000.
Abstract
Tight junction proteins ZO-1, ZO-2, and occludin along isolated renal tubules.
Background
Tight junctions play a critical role in tubular function. In mammalian kidney, the transepithelial electrical resistance and the complexity of the tight junction increase from the proximal to the collecting tubule. The differential expression of three tight junction proteins, ZO-1, ZO-2, and occludin, along isolated rabbit renal tubules is examined in this article.
Methods
Microdissected rabbit renal tubules were processed for immunofluorescence detection of ZO-1, ZO-2, and occludin. The quantitation of these proteins was done by Western blot determinations in Percoll isolated tubules.
Results
ZO-1 stained cell boundaries independently of the identity of the tubule. However, the amount found in distal segments was significantly higher than that expressed in proximal regions. ZO-2 in the proximal region was found diffusely distributed in the cytoplasm, with faint staining at cell borders, while a clear signal at cell perimeters was detectable from the Henle's loop to collecting tubules. Nuclear staining of ZO-2 was found along the whole nephron. The presence of occludin at the proximal region was faint and discontinuous, while its expression in the more distant portions was conspicuous. The quantity of ZO-2 and occludin present at the distal region was significantly higher compared with the proximal segment.
Conclusions
The distribution of ZO-1, ZO-2, and occludin follows the increase in junction complexity encountered in renal tubules. The amount of the three proteins found in proximal and distal segments is significantly higher in the latter.
Keywords:
MAGUK, transepithelial electrical resistance, paracellular ion barrier, cell polarity, nephron, confocal microscopy
