Mouse mpkCCD cells, Rat Kidney Proximal Tubule, and Rat Kidney Medullary Thick Ascending Limb

A series contains a set of transcript intensity values measured by Affymetrix microarray. This SuperSeries is composed of the SubSeries listed below. We used a systems biology-based approach to investigate the basis of cell-specific expression of the water channel aquaporin-2 (AQP2) in the renal collecting duct. Computational analysis of the 5’-flanking region of the AQP2 gene (GenomatixTM) revealed two conserved clusters of putative transcriptional regulator (TR) binding elements (BEs) at -513 bp (corresponding to SF1, NFAT and FKHD TR families) and -224 bp(correspnding to AP2, SRF, CREB, GATA, and HOX TR families). Three other conserved motifs corresponded to ETS, EBOX, and RXR TR families. To identify TRs that potentially bind to these BEs, we carried out mRNA profiling (Affymetrix) in mouse mpkCCDc14 collecting duct cells, revealing expression of 25 TRs that are also expressed in native inner medullary collecting duct (“IMCD Transcriptome Database”). One showed a significant positive correlation with AQP2 mRNA abundance among mpkCCD subclones (Ets1) and two showed a significant negative correlation (Elf1 and an orphan nuclear receptor Nr1h2). Transcriptomic profiling in native proximal tubules (PT), medullary thick ascending limbs (MTAL) and IMCDs from kidney identified 14 TRs (including Ets1 and HoxD3) expressed in the IMCD but not PT or TAL (candidate AQP2 enhancers), and 5 TRs (including HoxA5, HoxA9 and HoxA10) expressed in PT and TAL but not in IMCD (candidate AQP2 repressors). In luciferase reporter assays, overexpression of three ETS family TRs transactivated the mouse proximal AQP2 promoter. The results implicate ETS family TRs in cell-specific expression of AQP2 and point to HOX, RXR, CREB and GATA family TRs as playing likely additional roles.