Format

Send to

Choose Destination
Gastroenterology. 2010 Jul;139(1):304-14.e2. doi: 10.1053/j.gastro.2010.04.010. Epub 2010 Apr 14.

Activation of Trpv4 reduces the hyperproliferative phenotype of cystic cholangiocytes from an animal model of ARPKD.

Author information

1
Miles and Shirley Fiterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.

Abstract

BACKGROUND & AIMS:

In polycystic liver diseases, cyst formation involves cholangiocyte hyperproliferation. In polycystic kidney (PCK) rats, an animal model of autosomal-recessive polycystic kidney disease (ARPKD), decreased intracellular calcium [Ca(2+)](i) in cholangiocytes is associated with hyperproliferation. We recently showed transient receptor potential vanilloid 4 (Trpv4), a calcium-entry channel, is expressed in normal cholangiocytes and its activation leads to [Ca(2+)](i) increase. Thus, we hypothesized that pharmacologic activation of Trpv4 might reverse the hyperproliferative phenotype of PCK cholangiocytes.

METHODS:

Trpv4 expression was examined in liver of normal and PCK rats, normal human beings, and patients with autosomal-dominant polycystic kidney disease or ARPKD. Trpv4 activation effect on cell proliferation and cyst formation was assessed in cholangiocytes derived from normal and PCK rats. The in vivo effects of Trpv4 activation on kidney and liver cysts was analyzed in PCK rats.

RESULTS:

Trpv4 was overexpressed both at messenger RNA (8-fold) and protein (3-fold) levels in PCK cholangiocytes. Confocal and immunogold electron microscopy supported Trpv4 overexpression in the livers of PCK rats and ARPKD or autosomal-dominant polycystic kidney disease patients. Trpv4 activation in PCK cholangiocytes increased [Ca(2+)](i) by 30%, inhibiting cell proliferation by approximately 25%-50% and cyst growth in 3-dimensional culture (3-fold). Trpv4-small interfering RNA silencing blocked effects of Trpv4 activators by 70%. Trpv4 activation was associated with Akt phosphorylation and beta-Raf and Erk1/2 inhibition. In vivo, Trpv4 activation induced a significant decrease in renal cystic area and a nonsignificant decrease in liver cysts.

CONCLUSIONS:

Taken together, our in vitro and in vivo data suggest that increasing intracellular calcium by Trpv4 activation may represent a potential therapeutic approach in PKD.

PMID:
20399209
PMCID:
PMC2902576
DOI:
10.1053/j.gastro.2010.04.010
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center