Gene expression in murine colon mucosa following activation of stromal Hedgehog signalling

In the intestine, Hedgehog (Hh) signalling orchestrates epithelial homeostasis in a bidirectional loop. Differentiated enterocytes secrete the ligand leading to active downstream signaling exclusively in the stroma. In turn, Hh-driven stromal factors contribute to the control of intestinal stem cell numbers and induce epithelial differentiation. To investigate the consequences of stromal Hh activation on the gene expression level, we performed microarray analysis on full-thickness colonic tissue from Col1a2CreER;Ptch1fl/fl mice (C57BL/6 background). Upon Cre-driven recombination, these mice lack the inhibiting Hh receptor Ptch1 specifically in Col1a2 expressing stroma cells, leading to stroma-specific activation of downstream Hh signaling. RNA was isolated from 1 cm of fresh-frozen whole colonic tissue from Col1a2CreER;Ptch1fl/fl mice (n = 4) and controls (n = 4) starting 1.5 cm from the anus 7 days after administration of 5mg Tamoxifen i.p. to activate Cre. RNA quality was assessed using the Agilent 2200 Tape Station system; RNA integrity numbers (RIN) >8 were considered sufficient. Affymetrix Mouse Gene ST 2.0 arrays were used. Robust multi-array average (RMA) median polish procedures were applied for normalization.