Pyrene Fluorescence: A Potential Tool for Estimation of Short-Range Lateral Mobility in Membranes of Living Renal Epithelial Cells

1995 ◽  
Vol 18 (5) ◽  
pp. 246-253 ◽  
Author(s):  
Yasuhiro Ando ◽  
Yasushi Asano ◽  
Christian Le Grimellec
Keyword(s):  
Epithelial Cells ◽  
Short Range ◽  
Lateral Mobility ◽  
Renal Epithelial Cells ◽  
Pyrene Fluorescence ◽  
Potential Tool

scholarly journals Vasopressin V2-receptor mobile fraction and ligand-dependent adenylate cyclase activity are directly correlated in LLC-PK1 renal epithelial cells.

1991 ◽  
Vol 114 (1) ◽  
pp. 53-60 ◽  
Author(s):  
D A Jans ◽  
R Peters ◽  
P Jans ◽  
F Fahrenholz
Keyword(s):  
Signal Transduction ◽  
Epithelial Cells ◽  
Lateral Diffusion ◽  
Camp Production ◽  
Lateral Mobility ◽  
Renal Epithelial Cells ◽  
Transduction Mechanisms ◽  
Mobile Fraction ◽  
Temperature Pretreatment

The role of hormone receptor lateral mobility in signal transduction was studied using a cellular system in which the receptor mobile fraction could be reversibly modulated to largely varying extents. The G-protein-coupled vasopressin V2-type receptor was labeled in LLC-PK1 renal epithelial cells using a fluorescent analogue of vasopressin, and receptor lateral mobility measured using fluorescence microphotolysis (fluorescence photobleaching recovery). The receptor mobile fraction (f) was approximately 0.9 at 37 degrees C and less than 0.1 at 10 degrees C, in accordance with previous studies. When cells were incubated for 1 h at 4 degrees C without hormone, and then warmed up to 37 degrees C and labeled with the vasopressin analogue, f increased from approximately 0.4 to 0.8 over approximately 1 h. The apparent lateral diffusion coefficient was not markedly affected by temperature pretreatment. Studies with radiolabeled vasopressin indicated that temperature pretreatment influenced neither receptor number nor binding/internalization kinetics. F-actin staining revealed that temperature change resulted in reversible changes of cytoskeletal structure. The maximal rate of in vivo cAMP production at 37 degrees C in response to vasopressin, but not to forskolin (receptor-independent agonist), was also markedly influenced by preincubation of cells at 4 degrees C, thus paralleling the effects of temperature preincubation on f. A linear correlation between f and maximal cAMP production was observed, suggesting that the receptor mobile fraction is a key parameter in hormone signal transduction in vivo. We conclude that mobile receptors are required to activate G-proteins, and discuss the implications of this for signal transduction mechanisms.

Hormonal Regulation of Sodium/Sulfate Co-Transport in Renal Epithelial Cells

2000 ◽  
Vol 225 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Hwa Jeong Lee ◽  
Kazuko Sagawa ◽  
Wei Shi ◽  
Heini Murer ◽  
Marilyn E. Morris
Keyword(s):  
Epithelial Cells ◽  
Sodium Sulfate ◽  
Hormonal Regulation ◽  
Renal Epithelial Cells

scholarly journals Super-resolution microscopy reveals that Na+/K+-ATPase signaling protects against glucose-induced apoptosis by deactivating Bad

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Kristoffer Bernhem ◽  
Jacopo M. Fontana ◽  
Daniel Svensson ◽  
Liang Zhang ◽  
Linnéa M. Nilsson ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Chronic Diseases ◽  
Kidney Diseases ◽  
Super Resolution ◽  
Diabetic Patients ◽  
Diabetic Kidney ◽  
Renal Epithelial Cells ◽  
Apoptotic Process ◽  
Induced Apoptosis ◽  
Super Resolution Microscopy

AbstractActivation of the apoptotic pathway is a major cause of progressive loss of function in chronic diseases such as neurodegenerative and diabetic kidney diseases. There is an unmet need for an anti-apoptotic drug that acts in the early stage of the apoptotic process. The multifunctional protein Na+,K+-ATPase has, in addition to its role as a transporter, a signaling function that is activated by its ligand, the cardiotonic steroid ouabain. Several lines of evidence suggest that sub-saturating concentrations of ouabain protect against apoptosis of renal epithelial cells, a common complication and major cause of death in diabetic patients. Here, we induced apoptosis in primary rat renal epithelial cells by exposing them to an elevated glucose concentration (20 mM) and visualized the early steps in the apoptotic process using super-resolution microscopy. Treatment with 10 nM ouabain interfered with the onset of the apoptotic process by inhibiting the activation of the BH3-only protein Bad and its translocation to mitochondria. This occurred before the pro-apoptotic protein Bax had been recruited to mitochondria. Two ouabain regulated and Akt activating Ca2+/calmodulin-dependent kinases were found to play an essential role in the ouabain anti-apoptotic effect. Our results set the stage for further exploration of ouabain as an anti-apoptotic drug in diabetic kidney disease as well as in other chronic diseases associated with excessive apoptosis.

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