scholarly journals Urotensin II is an Autocrine/Paracrine Growth Factor for the Porcine Renal Epithelial Cell Line, LLCPK1

Endocrinology ◽  
2003 ◽  
Vol 144 (5) ◽  
pp. 1825-1831 ◽  
Author(s):  
Mika Matsushita ◽  
Masayoshi Shichiri ◽  
Nozomi Fukai ◽  
Naoko Ozawa ◽  
Takanobu Yoshimoto ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Kinase Inhibitor ◽  
Epithelial Cell Line ◽  
Urotensin Ii ◽  
Renal Epithelial Cell ◽  
Renal Epithelial Cells ◽  
Kinase C ◽  
Renal Epithelial Cell Line ◽  
Paracrine Growth Factor

Urotensin-II (UII), a cyclic dodecapeptide with potent cardiovascular effects, has recently been shown to be abundantly expressed in the human kidney and excreted in human urine. To investigate whether UII acts as an autocrine/paracrine growth factor for renal epithelial cells, we have studied the effects of human UII (hUII) on DNA synthesis, cytosolic free Ca2+ concentration ([Ca2+]i), ERK activation, and protooncogene (c-myc) expression in a porcine renal epithelial cell line (LLCPK1). hUII stimulated [3H]thymidine uptake into quiescent cells in a dose-dependent manner (10−9 to 10−7m); this effect was inhibited by a protein kinase C inhibitor (GF109203X), a MAPK kinase inhibitor (PD98059), and a calcium channel blocker (nicardipine). Neither phosphatidyl inositol-3 kinase inhibitors (LY294002, wortmannin) nor p38 kinase inhibitor (SB203580) affected the hUII-induced DNA syntheses. hUII rapidly (within 5 min) and dose-dependently (10−9 to 10−7m) increased [Ca2+]i in fura-2-loaded cells. hUII also caused a rapid and transient activation of ERK1/2 and induction of c-myc. LLCPK1 cells expressed UII mRNA and its receptor GPR14 mRNA, as determined by RT-PCR, and released UII-like immunoreactivity into media. Neutralization of endogenous UII by anti-hUII antibody, but not nonimmune serum, significantly suppressed DNA synthesis. These data suggest that hUII is an autocrine/paracrine growth factor for renal epithelial cells via activation of both protein kinase C and ERK1/2 pathways as well as Ca2+ influx via voltage-dependent Ca2+ channels.

SGK1 activates Na+-K+-ATPase in amphibian renal epithelial cells

2006 ◽  
Vol 290 (2) ◽  
pp. C492-C498 ◽  
Author(s):  
Diego Alvarez de la Rosa ◽  
Ignacio Gimenez ◽  
Biff Forbush ◽  
Cecilia M. Canessa
Keyword(s):  
Epithelial Cells ◽  
Cell Line ◽  
Direct Consequence ◽  
Fold Increase ◽  
Inducible Promoter ◽  
Epithelial Cell Line ◽  
Renal Epithelial Cell ◽  
Renal Epithelial Cells ◽  
Important Regulator ◽  
Renal Epithelial Cell Line

Serum- and glucocorticoid-induced kinase 1 (SGK1) is thought to be an important regulator of Na+ reabsorption in the kidney. It has been proposed that SGK1 mediates the effects of aldosterone on transepithelial Na+ transport. Previous studies have shown that SGK1 increases Na+ transport and epithelial Na+ channel (ENaC) activity in the apical membrane of renal epithelial cells. SGK1 has also been implicated in the modulation of Na+-K+-ATPase activity, the transporter responsible for basolateral Na+ efflux, although this observation has not been confirmed in renal epithelial cells. We examined Na+-K+-ATPase function in an A6 renal epithelial cell line that expresses SGK1 under the control of a tetracycline-inducible promoter. The results showed that expression of a constitutively active mutant of SGK1 (SGK1 TS425D) increased the transport activity of Na+-K+-ATPase 2.5-fold. The increase in activity was a direct consequence of activation of the pump itself. The onset of Na+-K+-ATPase activation was observed between 6 and 24 h after induction of SGK1 expression, a delay that is significantly longer than that required for activation of ENaC in the same cell line (1 h). SGK1 and aldosterone stimulated the Na+ pump synergistically, indicating that the pathways mediated by these molecules operate independently. This observation was confirmed by demonstrating that aldosterone, but not SGK1 TS425D, induced an ∼2.5-fold increase in total protein and plasma membrane Na+-K+-ATPase α1-subunit abundance. We conclude that aldosterone increases the abundance of Na+-K+-ATPase, whereas SGK1 may activate existing pumps in the membrane in response to chronic or slowly acting stimuli.

Three-dimensional Growth of Renal Epithelial Cells in Vitro: A Tool in Toxicity Testing

1993 ◽  
Vol 21 (2) ◽  
pp. 191-195 ◽  
Author(s):  
Knut-Jan Andersen ◽  
Erik Ilsø Christensen ◽  
Hogne Vik
Keyword(s):  
Epithelial Cells ◽  
Three Dimensional ◽  
Toxicity Testing ◽  
Renal Tissue ◽  
Epithelial Cell Line ◽  
Multicellular Spheroids ◽  
Renal Epithelial Cell ◽  
Renal Epithelial Cells

The tissue culture of multicellular spheroids from the renal epithelial cell line LLC-PK1 (proximal tubule) is described. This represents a biological system of intermediate complexity between renal tissue in vivo and simple monolayer cultures. The multicellular structures, which show many similarities to kidney tubules in vivo, including a vectorial water transport, should prove useful for studying the potential nephrotoxicity of drugs and chemicals in vitro. In addition, the propagation of renal epithelial cells as multicellular spheroids in serum-free culture may provide information on the release of specific biological parameters, which may be suppressed or masked in serum-supplemented media.

Electrophysiological Measurements of a Toad Renal Epithelial Cell Line (A6) as an Assay for Predicting Ocular Eye Irritancy

1992 ◽  
Vol 20 (2) ◽  
pp. 218-221
Author(s):  
Henning F. Bjerregaard
Keyword(s):  
Epithelial Cell ◽  
Cell Line ◽  
South African ◽  
Mdck Cells ◽  
Epithelial Cell Line ◽  
Renal Epithelial Cell ◽  
Electrophysiological Measurements ◽  
Renal Epithelial Cell Line ◽  
Darby Canine Kidney

An established epithelial cell line (A6) from a South African clawed toad (Xenopus laevis) kidney was used as a model for the corneal epithelium of the eye in order to determine ocular irritancy. When grown on Millipore filter inserts, A6 cells form a monolayer epithelium of high electrical resistance and generate a trans-epithelial potential difference. These two easily-measured electrophysiological endpoints showed a dose-related decrease after exposure for 24 hours to seven selected chemicals of different ocular irritancy potential. It was demonstrated that both trans-epithelial resistance and potential ranked closely with in vivo eye irritancy data and correlated well (r = 0.96) with loss of trans-epithelial impermeability of Madin-Darby canine kidney (MDCK) cells, detected by use of a fluorescein leakage assay.

Sign in / Sign up

Export Citation Format

Share Document