Adamts1 and Cyst Expansion in Polycystic Kidney Disease.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is characterized by mutations in either the Pkd1 or Pkd2 genes leading to progressive cyst growth and often kidney failure. We have previously demonstrated that tubules can enlarge following loss of Pkd1 without an increase in tubular cell numbers, suggesting that tubular basement membrane remodeling is important for cystic dilation. RNA sequencing of Pkd1 null kidneys revealed increased expression of 17 metalloproteinases, of which A Disintegrin and Metalloproteinase with Thrombospondin Motif 1 (Adamts1) is the most highly expressed and upregulated.

Methods: Mice were generated with inducible tubule-specific knockout of Adamts1 alone (AtsTKO), Pkd1 alone (PkdTKO), or both (P/ATKO) following doxycycline induction from 4-6 weeks age. Uninduced mice were used as controls. AtsTKO mice had no detectable phenotype through 12 weeks age.

Results: Upregulation of Adamts1 in PkdTKO kidneys correlated with a significant increase in the 70 kDa cleavage product of the V1 isoform of versican, which localized to the tubular basement membrane and adjacent interstitial mononuclear cells. Simultaneous deletion of both Adamts1 and Pkd1 (P/ATKO) reduced Adamts1 expression levels by >90%, prevented V1 versican cleavage, and reduced interstitial macrophage accumulation and activation. P/ATKO mice demonstrated reduced cystic enlargement, improved BUN and creatinine and better survival than did PkdTKO mice.

Conclusions: Preventing Adamts1 upregulation following loss of tubular Pkd1 effectively reduced cyst growth and preserved kidney function.