Mechanoregulation of intracellular Ca in human autosomal recessive polycystic kidney disease cyst-lining renal epithelial cells

Rohatgi R, Battini L, Kim P, Israeli S, Wilson PD, Gusella GL, Satlin LM. Mechanoregulation of intracellular Ca in human autosomal recessive polycystic kidney disease cyst-lining renal epithelial cells. Am J Physiol Renal Physiol 294: F890–F899, 2008. First published February 6, 2008; doi:10.1152/ajprenal.00341.2007.—Mutations of cilia-expressed proteins are associated with an attenuated shear-induced increase in intracellular Ca concentration ([Ca ]i) in renal epithelial cell lines derived from murine models of autosomal recessive polycystic kidney disease (ARPKD). We hypothesized that human ARPKD cyst-lining renal epithelial cells also exhibited dysregulated mechanosensation. To test this, conditionally immortalized cell lines derived from human fetal ARPKD cyst-lining (pool and clone 5E) cell lines with low levels of fibrocystin/polyductin expression and age-matched normal collecting tubule [human fetal collecting tubule (HFCT) pool and clone 2C] cell lines were grown in culture, loaded with a Ca indicator dye, and subjected to laminar shear. Clonal cell lines were derived from single cells present in pools of cells from cyst-lining and collecting tubules, microdissected from human kidney. Resting and peak [Ca ]i were similar between ARPKD 5E and pool, and HFCT 2C and pool; however, the flowinduced peak [Ca ]i was greater in ARPKD 5E (700 87 nM, n 21) than in HFCT 2C (315 58 nM, n 12; P 0.01) cells. ARPKD 5E cells treated with Gd , an inhibitor of nonselective cation channels, inhibited but did not abolish the shear-induced [Ca ]i transient. Cilia were 20% shorter in ARPKD than HFCT cells, but no difference in ciliary localization or total cellular expression of polycystin-2, a mechanosenory Gd -sensitive cation channel, was detected between ARPKD and HFCT cells. The intracellular Ca stores were similar between cells. In summary, human ARPKD cells exhibit an exaggerated Gd -sensitive mechano-induced Ca response compared with controls; whether this represents dysregulated polycystin-2 activity in ARPKD cells remains to be explored.