Enhanced apoptotic cell death of renal epithelial cells in mice lacking transcription factor AP-2β

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Abstract
Expression of AP-2 transcription factors has been detected previously in embryonic renal tissues. We show here thatAP-2β −/− mice complete embryonic development and die at postnatal days 1 and 2 because of polycystic kidney disease. Analyses of kidney development revealed that induction of epithelial conversion, mesenchyme condensation, and further glomerular and tubular differentiation occur normally in AP-2β-deficient mice. At the end of embryonic development expression of bcl-XL, bcl-w, and bcl-2 is down-regulated in parallel to massive apoptotic death of collecting duct and distal tubular epithelia. Addressing the molecular mechanism we show that transfection of AP-2 into cell lines in vitro strongly suppresses c-myc-induced apoptosis pointing to a function of AP-2 in programming cell survival during embryogenesis. The position of the human AP-2β gene was identified at chromosome 6p12–p21.1, within a region that has been mapped for autosomal recessive polycystic kidney disease (ARPKD). Sequence analyses of ARPKD patients and linkage analyses using intragenic polymorphic markers indicate that the AP-2β gene is located in close proximity to but distinct from the ARPKD gene.