Loss of Polycystin-1 in Human Cyst-Lining Epithelia Leads... : Journal of the American Society of Nephrology (original) (raw)

Genetics and Development

Loss of Polycystin-1 in Human Cyst-Lining Epithelia Leads to Ciliary Dysfunction

Nauli, Surya M.*; Rossetti, Sandro†; Kolb, Robert J.*; Alenghat, Francis J.‡; Consugar, Mark B.†; Harris, Peter C.†; Ingber, Donald E.‡; Loghman-Adham, Mahmoud§; Zhou, Jing*

*Renal Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts; †Division of Nephrology, Mayo Clinic College of Medicine, Rochester, Minnesota; ‡Vascular Biology Program, Departments of Pathology and Surgery, Children’s Hospital and Harvard Medical School, Boston, Massachusetts; and §Department of Pediatrics and Pediatrics Research Institute, St. Louis University School of Medicine, St. Louis, Missouri

Address correspondence to: Dr. Jing Zhou, Harvard Institutes of Medicine, Suite 520, 77 Avenue Louis Pasteur, Boston, MA 02115. Phone: 617-525-5860; Fax: 617-525-5861; E-mail: [email protected]

Accepted February 1, 2006

Received August 8, 2005

Abstract

A “two-hit” hypothesis predicts a second somatic hit, in addition to the germline mutation, as a prerequisite to cystogenesis and has been proposed to explain the focal nature for renal cyst formation in autosomal dominant polycystic kidney disease (ADPKD). It was reported previously that Pkd1null/null mouse kidney epithelial cells are unresponsive to flow stimulation. This report shows that Pkd1+/null cells are capable of responding to mechanical flow stimulation by changing their intracellular calcium concentration in a manner similar to that of wild-type cells. This paper reports that human renal epithelia require a higher level of shear stress to evoke a cytosolic calcium increase than do mouse renal epithelia. Both immortalized and primary cultured renal epithelial cells that originate from normal and nondilated ADPKD human kidney tubules display normal ciliary expression of the polycystins and respond to fluid-flow shear stress with the typical change in cytosolic calcium. In contrast, immortalized and primary cultured cyst-lining epithelial cells from ADPKD patients with mutations in PKD1 or with abnormal ciliary expression of polycystin-1 or -2 were not responsive to fluid shear stress. These data support a two-hit hypothesis as a mechanism of cystogenesis. This report proposes that calcium response to fluid-flow shear stress can be used as a readout of polycystin function and that loss of mechanosensation in the renal tubular epithelia is a feature of PKD cysts.