Cardiac defects and renal failure in mice with targeted mutations in Pkd2

Abstract

PKD2, mutations in which cause autosomal dominant polycystic kidney disease (ADPKD), encodes an integral membrane glycoprotein with similarity to calcium channel subunits. We induced two mutations in the mouse homologue Pkd2 (ref.4): an unstable allele (WS25; hereafter denoted Pkd2WS25) that can undergo homologous-recombination-based somatic rearrangement to form a null allele; and a true null mutation (WS183; hereafter denoted Pkd2-). We examined these mutations to understand the function of polycystin-2, the protein product of Pkd2, and to provide evidence that kidney and liver cyst formation associated with Pkd2 deficiency occurs by a two-hit mechanism. Pkd2-/- mice die in utero between embryonic day (E) 13.5 and parturition. They have structural defects in cardiac septation and cyst formation in maturing nephrons and pancreatic ducts. Pancreatic ductal cysts also occur in adult Pkd2WS25/- mice, suggesting that this clinical manifestation of ADPKD also occurs by a two-hit mechanism. As in human ADPKD, formation of kidney cysts in adult Pkd2WS25/- mice is associated with renal failure and early death (median survival, 65 weeks versus 94 weeks for controls). Adult Pkd2+/- mice have intermediate survival in the absence of cystic disease or renal failure, providing the first indication of a deleterious effect of haploinsufficiency at Pkd2on long-term survival. Our studies advance our understanding of the function of polycystin-2 in development and our mouse models recapitulate the complex human ADPKD phenotype.

Mutations in INVS encoding inversin cause nephronophthisis type 2, linking renal cystic disease to the function of primary cilia and left-right axis determination

“…40). In addition to the malformations described previously 41,42 , homozygous mutant embryos showed right pulmonary isomerism, randomization of embryonic turning, heart looping and abdominal situs inversus. In Pkd2 -/-mice, Leftb and Nodal were not expressed in the left lateral plate mesoderm, and Ebaf was absent from the floor-plate 40 .…”

Fibrocystin/Polyductin Modulates Renal Tubular Formation by Regulating Polycystin-2 Expression and Function

“…This result is consistent with studies in which transient small interference RNA-mediated inhibition of Pkhd1 in cholangiocytes resulted in shortening and decreased formation of cilia, 29 but spatial and environmental differences between in vivo tissues and in vitro cell culture may lead to different results. Mouse models with a deletion of Pkhd1 exon 40 44 and genetargeted mutations in Pkd2 that cause distinct liver and/or kidney cysts 33,45,46 do not exhibit defects in ciliary structure in the affected epithelial cells, suggesting that the failure of renal epithelia to assemble primary cilia may not be the only factor leading to cyst formation in the kidneys. For example, a recent study showed that disruption of the extracellular matrix protein laminin ␣5, which is a major component of the tubular and glomerular basement membranes, also produces cystic kidneys in Lama5 mutant mice.…”

“…32,33 To produce mutant mice for Pkhd1, we designed a targeting construct disrupting its 15th coding exon (Figure 1). We found 620 embryonic stem cell colonies resistant to G418, with one (W4A5) identified by PCR screening using a pair of outside-construct and cassette-based primers.…”

“…We discovered that lack of FPC was associated with the downregulation of PC2 expression in vivo. Renal cyst formation is more severe in mice BASIC RESEARCH www.jasn.org that are transmutant in Pkhd1 and Pkd2 (Pkd2 tm2Som ) 32,33 than in mice that are heterozygous for the Pkd2 mutation alone. In addition, we found that Pkd2-channel activities were dysregulated in primary cultures of renal epithelial cells derived from Pkhd1 mutant mice.…”

TRPP2-dependent Ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment inXenopus

“…Human PKD2 mutations are responsible for a large number of cases of autosomal dominant polycystic kidney disease (ADPKD) (Mochizuki et al, 1996) and null mutation of the murine ortholog Pkd2 is embryonic lethal. Pkd2 mutants exhibit severe cardio-vascular defects, and form cysts in developing nephrons and pancreatic duct (Wu et al, 2000). Morpholino-based loss of function of pkd2 also results in the formation of pronephric cysts during zebrafish development (Obara et al, 2006;Sun et al, 2004) and in the formation of severe edema and of dilated pronephric tubules in Xenopus (Tran et al, 2010).…”