Inhibition of human mesangial cell proliferation by targeting T-type calcium channels.
BACKGROUND
Aberrant glomerular mesangial cell (MC) proliferation is a common finding in renal diseases. T-type calcium channels (T-CaCN) play an important role in the proliferation of a number of cell types, including vascular smooth muscle cells. The hypothesis that T-CaCN may play a role in the proliferation of human MC was investigated.


METHODS
The presence of T-CaCN in primary cultures of human MC was examined using voltage clamping and by RT-PCR. The effect of calcium channel inhibitors, and of siRNA directed against the Cav3.2 T-CaCN isoform, on MC proliferation was assessed using the microculture tetrazolium assay and nuclear BrdU incorporation.


RESULTS
Human MC express only the Cav3.2 T-CaCN isoform. Co-incubation of MC with a T-CaCN inhibitor (mibefradil, TH1177 or Ni(2+)) results in a concentration-dependent attenuation of proliferation. This effect cannot be attributed to direct drug-induced cytotoxicity or apoptosis and is not seen with verapamil, an L-type channel blocker. Transfection of MC with siRNA results in knockdown of T-CaCN Cav3.2 mRNA and a clear attenuation of MC proliferation.


CONCLUSIONS
These results demonstrate for the first time an important role for T-CaCN in human MC proliferation. This could potentially lead to a novel therapy in the treatment of proliferative renal diseases.
Mulgrew
Christopher J
CJ
Department of Renal Medicine, King's College London, London, UK.
Cove-Smith
Andrea
A
McLatchie
Linda M
LM
Brooks
Gavin
G
Shattock
Michael J
MJ
Hendry
Bruce M
BM
D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000096:biosynthesis* / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D006801:Humans; D050527:Mesangial Cells / Q000187:drug effects* / Q000378:metabolism
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type