Abstract
In kidney, transcellular transport of Ca2+ is mediated by transient receptor potential vanilloid 5 and Na+-Ca2+ exchanger 1 proteins in distal convoluted and connecting tubules (DCT and CNT, respectively). It is not yet understood how DCT/CNT cells can adapt to differences in tubular flow rate and, consequently, Ca2+ load. This study aims to elucidate the molecular mechanisms by which DCT/CNT cells sense fluid dynamics to control transepithelial Ca2+ reabsorption and whether their primary cilia play an active role in this process. Mouse primary DCT/CNT cultures were subjected to a physiologic fluid shear stress (FSS) of 0.12 dyn/cm2 Transient receptor potential vanilloid 5 and Na+-Ca2+ exchanger 1 mRNA levels were significantly increased upon FSS exposure compared with static controls. Functional studies with 45Ca2+ demonstrated a significant stimulation of transepithelial Ca2+ transport under FSS compared with static conditions. Primary cilia removal decreased Ca2+ transport in both static and FSS conditions, a finding that correlated with decreased expression of genes involved in transepithelial Ca2+ transport; however, FSS-induced stimulation of Ca2+ transport was still observed. These results indicate that nephron DCT and CNT segments translate FSS into a physiologic response that implicates an increased Ca2+ reabsorption. Moreover, primary cilia influence transepithelial Ca2+ transport in DCT/CNT, yet this process is not distinctly coupled to FSS sensing by these organelles.-Mohammed, S. G., Arjona, F. J., Latta, F., Bindels, R. J. M., Roepman, R., Hoenderop, J. G. J. Fluid shear stress increases transepithelial transport of Ca2+ in ciliated distal convoluted and connecting tubule cells.
