TY - JOUR
T1 - Mechanical force-activated phospholipase D is mediated by Gα12/13-Rho and calmodulin-dependent kinase in renal epithelial cells
AU - Ziembicki, Jenny
AU - Tandon, Rajnish
AU - Schelling, Jeffrey R.
AU - Sedor, John R.
AU - Miller, R. Tyler
AU - Huang, Chunfa
PY - 2005/10
Y1 - 2005/10
N2 - The renal glomerulus, the site of plasma ultrafiltration, is exposed to mechanical force in vivo arising from capillary blood pressure and fluid flow. Studies of cultured podocytes demonstrate that they respond to stretch by altering the structure of the actin cytoskeleton, but the mechanisms by which physical force triggers this architectural change and the signaling pathways that lead to generation of second messengers are not defined. In the present study, we found that in renal epithelial cells [podocytes and Madin-Darby canine kidney (MDCK) cells], application of mechanical force to the cell surface through fibronectin-coated ferric beads and exposure of the cells to magnetic force lead to Rho translocation and actin cytoskeleton reorganization. This application of force recruited Rho and filamentous actin (F-actin) to bead loci and subsequently stimulated phospholipase D (PLD), a downstream effector of Rho. Using MDCK cells that stably express regulators of G protein-signaling (RGS) proteins [RGS4 attenuates Gαi and Gαq, and the p115RhoGEF-RGS domain (p115-RGS) attenuates Gα12/13] to define the signaling pathway, we found that mechanical force induced Gα12/13-Rho activation and increased F-actin to stimulate PLD activity. The activation can be partially prevented by the C3 exoenzyme. Pretreatment of the cells with chemical inhibitors of several kinases showed that calmodulin-dependent kinase is also involved in stretch-induced PLD activation by a separate pathway. Taken together, our data demonstrate that in cultured podocytes and MDCK cells, mechanical force leads to actin cytoskeleton reorganization and PLD activation. The signaling pathways for PLD activation involve Gα12/13/Rho/F-actin and calmodulin-dependent kinase.
AB - The renal glomerulus, the site of plasma ultrafiltration, is exposed to mechanical force in vivo arising from capillary blood pressure and fluid flow. Studies of cultured podocytes demonstrate that they respond to stretch by altering the structure of the actin cytoskeleton, but the mechanisms by which physical force triggers this architectural change and the signaling pathways that lead to generation of second messengers are not defined. In the present study, we found that in renal epithelial cells [podocytes and Madin-Darby canine kidney (MDCK) cells], application of mechanical force to the cell surface through fibronectin-coated ferric beads and exposure of the cells to magnetic force lead to Rho translocation and actin cytoskeleton reorganization. This application of force recruited Rho and filamentous actin (F-actin) to bead loci and subsequently stimulated phospholipase D (PLD), a downstream effector of Rho. Using MDCK cells that stably express regulators of G protein-signaling (RGS) proteins [RGS4 attenuates Gαi and Gαq, and the p115RhoGEF-RGS domain (p115-RGS) attenuates Gα12/13] to define the signaling pathway, we found that mechanical force induced Gα12/13-Rho activation and increased F-actin to stimulate PLD activity. The activation can be partially prevented by the C3 exoenzyme. Pretreatment of the cells with chemical inhibitors of several kinases showed that calmodulin-dependent kinase is also involved in stretch-induced PLD activation by a separate pathway. Taken together, our data demonstrate that in cultured podocytes and MDCK cells, mechanical force leads to actin cytoskeleton reorganization and PLD activation. The signaling pathways for PLD activation involve Gα12/13/Rho/F-actin and calmodulin-dependent kinase.
KW - Podocytes
KW - Signaling
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U2 - 10.1152/ajprenal.00412.2004
DO - 10.1152/ajprenal.00412.2004
M3 - Article
C2 - 15914773
AN - SCOPUS:24944536654
SN - 0363-6127
VL - 289
SP - F826-F834
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 4 58-4
ER -