Functional distinctions in cytosolic calcium regulation between cells of the glomerular filtration barrier

Abstract The importance of intracellular calcium ([Ca2+ ]i ) regulation in the glomerular filtration barrier (GFB) has recently been highlighted by mutations in the cation channel TRPC6, resulting in a renal-specific phenotype. We examined the effects of FFA, a tool that can activate TRPC6, on [Ca2+...

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Bibliographic Details
Published in:Cell calcium (Edinburgh) 2010-07, Vol.48 (1), p.44-53
Main Authors: Foster, Rebecca Rachael, Welsh, Gavin I, Satchell, Simon C, Marlow, Robin D, Wherlock, Mathew D, Pons, Debora, Mathieson, Peter W, Bates, David O, Saleem, Moin A
Format: Article
Language:English
Subjects:
Advanced Basic Science
Calcium
Calcium - metabolism
Cells, Cultured
Cytosol - metabolism
Endothelial Cells - drug effects
Endothelial Cells - physiology
Flufenamic acid
Flufenamic Acid - pharmacology
Glomerular endothelial cells
HEK293 Cells
Humans
Kidney Glomerulus - cytology
Kidney Glomerulus - metabolism
Membrane Proteins - physiology
Podocytes
Podocytes - metabolism
TRPC Cation Channels - physiology
TRPC6
TRPC6 Cation Channel
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Summary:Abstract The importance of intracellular calcium ([Ca2+ ]i ) regulation in the glomerular filtration barrier (GFB) has recently been highlighted by mutations in the cation channel TRPC6, resulting in a renal-specific phenotype. We examined the effects of FFA, a tool that can activate TRPC6, on [Ca2+ ]i in human conditionally immortalised glomerular endothelial cells (ciGEnC) and human podocytes (ciPod) that form the GFB. Changes in [Ca2+ ]i stimulated by FFA were measured in Fura 2-AM loaded cells. In GEnC, cell activation by FFA was dependent on external Ca2+ , yet in ciPod it was not. Depletion of internal Ca2+ stores with thapsigargin did not affect cell activation by FFA in ciGEnC, but inhibited it in ciPod in a nephrin-dependent manner, demonstrated using nephrin deficient (ND) ciPod in conjunction with nephrin rescue experiments. FFA induced [Ca2+ ]i store release in ciPod, but not in ciGEnC or ND ciPod. In parallel, there were differences in the localisation of overexpressed TRPC6 between ciGEnC and ciPod. Furthermore, co-transfection of nephrin with TRPC6 in HEK293 cells reduced the FFA-induced increase in [Ca2+ ]i and nephrin clustering altered TRPC6 distribution. In conclusion, cell activation by FFA in podocytes stimulates the opening of a Ca2+ channel, probably TRPC6, in a nephrin-dependent manner with a different activation profile to GEnC.
ISSN:0143-4160
1532-1991
DOI:10.1016/j.ceca.2010.06.005