Metanephric rat-mouse chimeras to study cell lineage of the nephron

The nephron is derived from the ureteric bud and metanephric mesenchyme and develops into a complex epithelial structure with a wide variety of phenot ypes along iis length. This segmental variation in expression of molecules provides an approach to understand the lineage of unique segments. present study evaluated the expression of four relatively well-localized molecules - renin, Tamm-Horsfall protein (THP), oxytocin receptor (OTR), and the vaso pressin type 2 receptor (V2R) - in cultured mouse-rat chimeric metanephric kidneys using reverse transcription-polymerase chain reaction (RT-PCR). Chi meric kidneys were formed by 1) separating the ureteric bud (U) from the me tanephric mesenchyme (M) of mouse (m) at E11 and rat (r) at E13 days of ges tation and 2) recombining the ureteric bud of one species with the metaneph ric mesenchyme of the other species (i.e., UrMm and UmMr), followed by filt er culture until differentiated. Species-specific restriction enzymes for a ll four genes were chosen to digest the PCR product from either rat or mous e. RT-PCR was performed for each mRNA species and the products digested. Th e V2R product from the UrMm chimera was cleaved by a restriction enzyme kno wn to digest only rat product, suggesting the PCR product was produced pred ominantly by cells derived from the ureteric bud. The renin, OTR, and THP p roducts from both chimeras were cleaved equally well by species-specific re striction enzymes, suggesting the products were made by cells originating f rom both the ureteric bud and the metanephric mesenchyme. These studies dem onstrate that the cultured chimeric metanephric model is useful to study se gment lineage. The results suggest that the lineage of at least ceria in po rtions of the nephron is heterogenous. (C) 1999 Wiley-Liss, Inc.