Effect on Dome Formation and Uptake of Ochratoxin A in Proximal Tubule-Derived Opossum Kidney Cell Monolayers

1993 ◽  
Vol 3 (1) ◽  
pp. 68-77 ◽  
Author(s):  
Michael Gekle ◽  
Stefan Silbernagl ◽  
Sigrid Mildenberger ◽  
Ruth Freudinger
Keyword(s):  
Proximal Tubule ◽  
Ochratoxin A ◽  
Kidney Cell ◽  
Dome Formation ◽  
Opossum Kidney ◽  
Cell Monolayers ◽  
Opossum Kidney Cell

scholarly journals The Opossum Kidney Cell Type IIa Na/Pi Cotransporter Is a Phosphoprotein

2001 ◽  
Vol 24 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Maciej Jankowski ◽  
Helene Hilfiker ◽  
Jürg Biber ◽  
Heini Murer
Keyword(s):  
Kidney Cell ◽  
Cell Type ◽  
Opossum Kidney ◽  
Opossum Kidney Cell

Parathyroid Hormone Degradation by Chymotrypsin-Like Endopeptidase in the Opossum Kidney Cell*

Endocrinology ◽  
1988 ◽  
Vol 123 (6) ◽  
pp. 2812-2817 ◽  
Author(s):  
TORU YAMAGUCHI ◽  
MASAAKI FUKASE ◽  
MASASHI NISHIKAWA ◽  
TADAO FUJIMI ◽  
TAKUO FUJITA
Keyword(s):  
Parathyroid Hormone ◽  
Kidney Cell ◽  
Opossum Kidney ◽  
Opossum Kidney Cell

scholarly journals Distinct functions of megalin and cubilin receptors in recovery of normal and nephrotic levels of filtered albumin

2020 ◽  
Vol 318 (5) ◽  
pp. F1284-F1294 ◽  
Author(s):  
Qidong Ren ◽  
Kathrin Weyer ◽  
Youssef Rbaibi ◽  
Kimberly R. Long ◽  
Roderick J. Tan ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Binding Capacity ◽  
Fluid Phase ◽  
Albumin Binding ◽  
Opossum Kidney ◽  
Opossum Kidney Cell ◽  
Uptake Sites ◽  
High Concentrations ◽  
The Individual

Proximal tubule (PT) cells express a single saturable albumin-binding site whose affinity matches the estimated tubular concentration of albumin; however, albumin uptake capacity is greatly increased under nephrotic conditions. Deciphering the individual contributions of megalin and cubilin to the uptake of normal and nephrotic levels of albumin is impossible in vivo, as knockout of megalin in mice globally disrupts PT endocytic uptake. We quantified concentration-dependent albumin uptake in an optimized opossum kidney cell culture model and fit the kinetic profiles to identify albumin-binding affinities and uptake capacities. Mathematical deconvolution fit best to a three-component model that included saturable high- and low-affinity uptake sites for albumin and underlying nonsaturable uptake consistent with passive uptake of albumin in the fluid phase. Knockdown of cubilin or its chaperone amnionless selectively reduced the binding capacity of the high-affinity site, whereas knockdown of megalin impacted the low-affinity site. Knockdown of disabled-2 decreased the capacities of both binding sites. Additionally, knockdown of megalin or disabled-2 profoundly inhibited the uptake of a fluid phase marker, with cubilin knockdown having a more modest effect. We propose a novel model for albumin retrieval along the PT in which cubilin and megalin receptors have different functions in recovering filtered albumin in proximal tubule cells. Cubilin binding to albumin is tuned to capture normally filtered levels of the protein. In contrast, megalin binding to albumin is of lower affinity, and its expression is also essential for enabling the recovery of high concentrations of albumin in the fluid phase.

Citrate transport in proximal cell line

1992 ◽  
Vol 263 (1) ◽  
pp. C220-C225 ◽  
Author(s):  
D. Law ◽  
K. S. Hering-Smith ◽  
L. L. Hamm
Keyword(s):  
Proximal Tubule ◽  
Cell Line ◽  
Transport Process ◽  
Competitive Inhibition ◽  
Basolateral Membrane ◽  
Opossum Kidney ◽  
Cell Monolayers ◽  
Citrate Transport ◽  
Sodium Dependent ◽  
A Cell

Citrate uptake into kidney proximal tubules occurs via an apical dicarboxylate transporter and a poorly characterized process in the basolateral membrane. We used OK cells, a cell line derived from opossum kidney, to study citrate transport in proximal tubule-like cells. Citrate uptake into cell monolayers was studied using [14C]citrate with [3H]mannitol as a volume marker. Citrate uptake into these cells was sodium dependent and saturable with increasing concentrations of citrate. In contrast to previous models, citrate transport was altered minimally by changes in pH from 6.2 to 7.0 and increased at pH 7.4 to 7.8. A variety of di- and tricarboxylates were tested for interaction with citrate transport. The dicarboxylates succinate, malate, and oxaloacetate at 1 mM concentration inhibited citrate uptake minimally (uptake at least 80% of control); one dicarboxylate, alpha-ketoglutarate, did inhibit citrate uptake significantly. In contrast, the tricarboxylates isocitrate and tricarballylate inhibited citrate uptake significantly, indicating probable competitive inhibition with the transport process. These characteristics are distinctly different from those of the apical membrane dicarboxylate transporter. 1,2,3-Benzenetricarboxylic acid, an inhibitor of the mitochondrial tricarboxylate transporter, did not alter citrate uptake. In conclusion, the OK proximal cell line exhibits a novel citrate transport process compared with the apical transport of citrate described in most proximal systems. This transport process probably involves the trivalent species of citrate in contrast to the usual predominant transport of divalent citrate. This transport process may represent a process similar to that in the basolateral membrane of the proximal tubule.

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