Guay-Woodford, Lisa M. Murine models of polycystic kidney disease: molecular and therapeutic insights. Am J Physiol Renal Physiol 285: F1034-F1049, 2003 10.1152/ajprenal. 00195.2003.-Numerous murine (mouse and rat) models of polycystic kidney disease (PKD) have been described in which the mutant phenotype results from a spontaneous mutation or engineering via chemical mutagenesis, transgenic technologies, or gene-specific targeting in mouse orthologs of human PKD genes. These murine phenotypes closely resemble human PKD, with common abnormalities observed in tubular epithelia, the interstitial compartment, and the extracellular matrix of cystic kidneys. In both human and murine PKD, genetic background appears to modulate the renal cystic phenotype. In murine models, these putative modifying effects have been dissected into discrete factors called quantitative trait loci and genetically mapped. Several lines of experimental evidence support the hypothesis that PKD genes and their modifiers may define pathways involved in cystogenesis and PKD progression. Among the various pathway abnormalities described in murine PKD, recent provocative data indicate that structural and/or functional defects in the primary apical cilia of tubular epithelia may play a key role in PKD pathogenesis. This review describes the most widely studied murine models; highlights the data regarding specific gene defects and genetic modifiers; summarizes the data from these models that have advanced our understanding of PKD pathogenesis; and examines the effect of various therapeutic interventions in murine PKD.autosomal dominant polycystic kidney disease; autosomal recessive polycystic kidney disease; polycystic kidney disease quantitative trait loci; polycystic kidney disease therapeutics RENAL TUBULAR CYSTS DEVELOP in several inherited human disorders. Among these, the polycystic kidney diseases (PKD) are one of the leading causes of endstage renal disease in children and adults (31). Autosomal dominant polycystic kidney disease (ADPKD) occurs in 1:1,000 individuals, primarily as the result of mutations in one of two genes, PKD1 or PKD2 (81,(150)(151)(152). In comparison, autosomal recessive polycystic kidney disease (ARPKD) is much less frequent (1: 20,000 live births) and results primarily from mutations in a single gene, PKHD1 (107, 162).The principal pathological manifestations in PKD involve 1) the formation of epithelial-lined cysts throughout the nephron in ADPKD and predominantly in the collecting duct in ARPKD; 2) alterations in cell polarity; and 3) changes in extracellular matrix composition. In addition to the renal cystic disease, ADPKD is associated with cyst formation in other epithelial organs, most notably the liver and pancreas, as well as connective tissue defects, such as intracranial aneurysms, aortic dissection, cardiac valve abnormalities, and abdominal wall hernias (116). In comparison, the ARPKD phenotype is expressed almost exclusively in the kidney and liver, with the latter lesion involving biliary dysgenesis a...