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Renal tubule protein transcytosis

Ming Chang Hu, Mingjun Shi, Jianning Zhang, Tayo Addo, Han Ju Cho, Sarah L Barker, Priya Ravikumar, Nancy Gillings, Ao Bian, Sachdev S Sidhu, Makoto Kuro-o, Orson W Moe
αKlotho is a multifunctional protein highly expressed in the kidney. Soluble αKlotho is released through cleavage of the extracellular domain from membrane αKlotho by secretases to function as an endocrine/paracrine substance. The role of the kidney in circulating αKlotho production and handling is incompletely understood, however. Here, we found higher αKlotho concentration in suprarenal compared with infrarenal inferior vena cava in both rats and humans. In rats, serum αKlotho concentration dropped precipitously after bilateral nephrectomy or upon treatment with inhibitors of αKlotho extracellular domain shedding...
January 2016: Journal of the American Society of Nephrology: JASN
Verena Tenten, Sylvia Menzel, Uta Kunter, Eva-Maria Sicking, Claudia R C van Roeyen, Silja K Sanden, Michaela Kaldenbach, Peter Boor, Astrid Fuss, Sandra Uhlig, Regina Lanzmich, Brigith Willemsen, Henry Dijkman, Martin Grepl, Klemens Wild, Wilhelm Kriz, Bart Smeets, Jürgen Floege, Marcus J Moeller
Under physiologic conditions, significant amounts of plasma protein pass the renal filter and are reabsorbed by proximal tubular cells, but it is not clear whether the endocytosed protein, particularly albumin, is degraded in lysosomes or returned to the circulatory system intact. To resolve this question, a transgenic mouse with podocyte-specific expression of doxycycline-inducible tagged murine albumin was developed. To assess potential glomerular backfiltration, two types of albumin with different charges were expressed...
December 2013: Journal of the American Society of Nephrology: JASN
Krzysztof Golab, Jakub Gburek, Bogusława Konopska, Hubert Krotkiewski, Maria Warwas
Glycated proteins are considered as one of the factors involved in the pathogenesis of diabetic complications, including nephropathy. These proteins are formed endogenously under conditions of hyperglycemia, as well as being provided with food containing sugars, which was subjected to high temperature. Examples are egg products. One of the proteins found in eggs in a relatively high concentration is chicken cystatin (ovocystatin). It is now believed that some proteins can passage the intestinal epithelium by transcytosis directly into the bloodstream...
October 2013: Animal Science Journal, Nihon Chikusan Gakkaihō
Jakub Gburek, Krzysztof Gołąb, Katarzyna Juszczyńska
Albumin is the main protein of blood plasma, lymph, cerebrospinal fluid and interstitial fluid. The protein assists in many important body functions, including maintenance of proper colloidal osmotic pressure, transport of important metabolites and antioxidant action. Synthesis of albumin takes place mainly in the liver, and its catabolism occurs mostly in vascular endothelium of muscle, skin and liver as well as in the kidney tubular epithelium. Renal catabolism of albumin consists of glomerular filtration and tubular reabsorption...
2011: Postȩpy Higieny i Medycyny Doświadczalnej
Marcus Pohl, Henriette Kaminski, Hayo Castrop, Michael Bader, Nina Himmerkus, Markus Bleich, Sebastian Bachmann, Franziska Theilig
The existence of a local renin angiotensin system (RAS) of the kidney has been established. Angiotensinogen (AGT), renin, angiotensin-converting enzyme (ACE), angiotensin receptors, and high concentrations of luminal angiotensin II have been found in the proximal tubule. Although functional data have documented the relevance of a local RAS, the dualism between biosynthesis and endocytotic uptake of its components and their cellular processing has been incompletely understood. To resolve this, we have selectively analyzed their distribution, endocytosis, transcytosis, and biosynthesis in the proximal tubule...
December 31, 2010: Journal of Biological Chemistry
L M Russo, R M Sandoval, M McKee, T M Osicka, A B Collins, D Brown, B A Molitoris, W D Comper
The origin of albuminuria remains controversial owing to difficulties in quantifying the actual amount of albumin filtered by the kidney. Here we use fluorescently labeled albumin, together with the powerful technique of intravital 2-photon microscopy to show that renal albumin filtration in non-proteinuric rats is approximately 50 times greater than previously measured and is followed by rapid endocytosis into proximal tubule cells (PTCs). The endocytosed albumin appears to undergo transcytosis in large vesicles (500 nm in diameter), identified by immunogold staining of endogenous albumin by electron microscopy, to the basolateral membrane where the albumin is disgorged back to the peritubular blood supply...
March 2007: Kidney International
B Comte, C Franceschi, M-O Sadoulet, F Silvy, D Lafitte, L Benkoel, A Nganga, L Daniel, J-P Bernard, D Lombardo, E Mas
Bile salt-dependent lipase (BSDL), a 110 kDa glycoprotein secreted by the pancreatic acinar cells, participates in the duodenal hydrolysis of dietary lipid esters. Recent in vitro and in vivo studies demonstrated that the BSDL reaches the blood via a transcytosis motion through enterocytes, suggesting that this enzyme may play a role in vascular biology. Once in the blood, BSDL should be eliminated. We address the hypothesis that BSDL may be filtered by the glomerulus and eliminated in urines. Immunological methods and proteomic were used to detect and to characterize BSDL in urine...
March 2006: Kidney International
Ivan Sabolić, Carol Mirna Herak-Kramberger, Marija Ljubojević, Daniel Biemesderfer, Dennis Brown
BACKGROUND: Depolymerization of microtubules in proximal tubule (PT) cells of colchicine-treated rats causes disruption of vesicle recycling and redistribution of some brush-border membrane (BBM) transporters into cytoplasmic vesicles. NHE3, an isoform of the Na+/H+ exchanger in the PT cell BBM, is acutely regulated by a variety of mechanisms, including protein trafficking and interaction with the PDZ protein, NHERF. The effects of microtubule disruption by colchicine on NHE3 trafficking in PT and the potential role of NHERF in this process have not been studied...
April 2002: Kidney International
Noriyoshi Kobayashi, Yusuke Suzuki, Toshinao Tsuge, Ko Okumura, Chisei Ra, Yasuhiko Tomino
In the kidney, proteins filtered through glomeruli are reabsorbed by endocytosis along the proximal tubules to avoid renal loss of large amounts of proteins. Recently, neonatal Fc receptor (FcRn), which is involved in the transport of IgG across several epithelial and endothelial cells, was reported to be expressed in renal proximal tubular epithelial cells (RPTECs). However, there has been no direct evidence for receptor-mediated endocytosis of IgG in human RPTECs. To explore physiological roles of FcRn in the proximal tubules, we used the human RPTECs to examine IgG transport...
February 2002: American Journal of Physiology. Renal Physiology
M Marinó, D Andrews, D Brown, R T McCluskey
Plasma retinol-binding protein (RBP) combined with vitamin A (retinol) is partially filtered through the glomerulus and then absorbed by proximal tubule cells, leading to recycling of retinol to the circulation. Recently, it was shown that reabsorption of RBP-retinol complexes by proximal tubule cells is mediated by megalin (gp 330), an apical endocytic receptor. It was proposed that RBP is transported by megalin to lysosomes, where it is degraded, thus liberating retinol, which then combines with newly synthesized RBP to be secreted into the bloodstream...
April 2001: Journal of the American Society of Nephrology: JASN
S Cui, S Nielsen, T Bjerke, E I Christensen
The purposes of this study were (1) to determine whether or not transcytosis of protein takes place in vivo in rabbit proximal tubules, using ferritin as a marker, (2) to follow the time course of intracellular transport of ferritin, (3) to study the organelles involved in the sequential intracellular transport of the protein, (4) to compare the intracellular transport in vivo and in vitro, and (5) to compare the intracellular transport in rabbit proximal tubules with transport in rat proximal tubules. Female albino rabbits were prepared for micropuncture, and individual proximal tubules were microinfused with a bolus of cationic ferritin for 2-3 min...
September 1993: Experimental Nephrology
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