Publikationsserver der RWTH Aachen University
Identifizierung und Charakterisierung von Pkhd1, dem Maus-Ortholog des humanen ARPKD-Gens, sowie Erstellung und Analyse einer Pkhdl mutierten Maus
Abstract
dc:descriptionAutosomal recessive polycystic kidney disease (ARPKD) is an inherited disorder causing renal-related and liver-related morbidity and mortality in childhood, characterized by renal cysts, biliary dysgenesis and congenital hepatic fibrosis due to ductal plate malformation. With an estimated incidence of 1 in 20,000 up to 50% of the affected neonates die shortly after birth. ARPKD is caused by mutations in a single gene (Pkhd1, polycystic kidney and hepatic disease 1) that is assembled in a complex pattern of alternative splice variants and has recently been identified. The murine Pkhd1 and its translation products have very similar properties to its human orthologue. Mouse Pkhd1 extends over approximately 500 kb of genomic DNA and includes a minimum of 68 exons. The longest ORF encodes the 4059-amino acid protein polyductin, predicted to have multiple IPTs and PbH1 repeats and a single membrane spanning domain. Northern blot analysis of the Pkhd1 expression pattern in murine tissues using two different cDNA probes reveal a prominent band of about 13 kb that is strongly expressed in kidney tissue. An alternative, smaller transcript is recognized only in testis and only by a probe derived from Pkhd1 exon 40. In situ hybridization in developing and adult mouse tissues show high levels of expression in renal and biliary tubular structures as well as strong signals in some other tissues. To investigate the role of polyductin during mouse embryonic development, knockout mice were constructed harbouring a targeted germline mutation in exon 40 of the PKHD1 gene. Due to exon skipping, PKHD1ex40 mice express a modified transcript generated from the mutated Pkhd1 by an in frame deletion of exon 40. Mice of all genotypes are viable and fertile. PKHD1ex40 (-/-) mice develop severe malformations of intrahepatic bile ducts. Cholangiocytes maintain a proliferative phenotype and continuously immunoreact with TGF-ß1. Subsequently, mesenchymal cells within the hepatic portal tracts continue to synthesize collagen resulting in progressive portal fibrosis. The pathogenetic changes leading to congenital hepatic fibrosis in mice are absolutely equivalent to the liver disease in human ARPKD patients. These findings indicate that subsequent to formation of the embryonic ductal plate, polyductin is required for terminal differentiation of intrahepatic bile ducts, possibly acting as a signal receptor. In contrast to human ARPKD individuals, PKHD1ex40 mice develop morphologically and functionally normal kidneys. Hence, the role of polyductin in liver and kidney seems to be functionally divergent.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2003
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
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- Matthiesen, Sonja
- Contributors dc:contributor
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- Büttner, Reinhard
Subjects
dc:subject × 5Rights
dc:rights- Statement dc:rights
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- info:eu-repo/semantics/openAccess
- Language dc:language
- ger