Related Experiment Video
Updated: Jul 3, 2026

Identification of the Source of Secreted Proteins in the Kidney by Brefeldin A Injection
Published on: November 10, 2021
Tight junction claudins and the kidney in sickness and in health
1Veterans Administration Medical Center, University of Alabama at Birmingham, Birmingham, AL 35294-0007, USA. balkovet@uab.edu
Abstract:
The epithelial cell tight junction has several functions including the control of paracellular transport between epithelial cells. Renal paracellular transport has been long recognized to exhibit unique characteristics within different segments of the nephron, functions as an important component of normal renal physiology and has been speculated to contribute to renal related pathology if functioning abnormally. The discovery of a large family of tight junction associated 4-transmembrane spanning domain proteins named claudins has advanced our understanding on how the paracellular permeability properties of tight junctions are determined. In the kidney, claudins are expressed in a nephron-specific pattern and are major determinants of the paracellular permeability of tight junctions in different nephron segments. The combination of nephron segment claudin expression patterns, inherited renal diseases, and renal epithelial cell culture models is providing important clues about how tight junction claudin molecules function in different segments of the nephron under normal and pathological conditions. This review discusses early observations of renal tubule paracellular transport and more recent information on the discovery of the claudin family of tight junction associated membrane proteins and how they relate to normal renal function as well as diseases of the human kidney.
Related Concept Videos
Tight Junctions
Physiology of the Genitourinary System II: Tubular Reabsorption and Secretion
Renal Tubule and Collecting Duct
Proximal Convoluted Tubule (PCT):
The PCT is the initial segment of the renal tubule, extending from the Bowman's capsule that encloses the glomerulus. Its convoluted structure and microvilli-lined cells increase the surface area for reabsorption. The PCT reabsorbs glucose, amino acids, sodium, and water from the filtrate, ensuring essential...
Nephrons
Formation of Dilute Urine
Filtrate Osmolarity in the PCT
Initially, as the filtrate passes through the proximal convoluted tubule (PCT), its...
Tubular Reabsorption and Secretion
Tubular reabsorption is a selective process that starts when the filtrate enters the proximal tubules. It involves substances traveling through the transcellular route (through the tubule cell and peritubular...

