Premium
ATP induced Ca 2+ activated Cl − conductance is dependent on VMD2 (bestrophin‐1) expression
Author(s) -
Schreiber Rainer,
Sorria René Barro,
Milenkovic Vladimir,
Spitzner Melanie,
Hieke Bernhard,
Kunzelmann Karl
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1328
Subject(s) - purinergic receptor , biology , epithelial sodium channel , amiloride , microbiology and biotechnology , chemistry , sodium , extracellular , organic chemistry
In kidney epithelial cells stimulation of P2Y 2 receptor by ATP activates a Ca 2+ activated Cl − conductance (CaCC) and inhibits amiloride‐ sensitive Na + transport. Additionally activation of CaCC could be involved in kidney diseases. In polycystic kidney purinergic activation of CaCC could cause formation of cysts and cyst volume expansion. The molecular identity of CaCC in epithelial tissues is not known. We demonstrate molecular and functional expression of vitelliform macular dystrophy gene (VMD2, bestrophin‐1) in epithelial cells of airways, colon and kidney of mouse and human. ATP induced endogenous CaCC coincide with endogenous expression of VMD2. Whereas CaCC are absent in epithelial tissues lacking VMD2 expression. Blocking expression of VMD2 with sRNAi or applying a VMD2 antibody to the patch pipette suppressed ATP induced whole cell Cl − currents. CaCC is activated by ATP in HEK293 cells overexpressing VMD2. Ussing chamber experiments with collecting duct cells (M1 cells) are showing time or cell density dependence of ATP induced CaCC. In young filter cultures of M1 cells with low amiloride‐ sensitive Na + transport ATP induces CaCC. In contrast in elder filter cultures of M1 cells with a high amiloride‐ sensitive Na + transport ATP induces a K + secretion. Semiquantitative RT‐PCR shows higher expression of VMD2 genes in young filter cultures. In summary we conclude that VMD2 may form or be a component of the ATP induced Cl − channel and that the expression of the ATP induced Cl − channel is dependent on cell differentiation. This work was supported by Deutsche Forschungsgemeinschaft (DFG, SFB 699).