Gene expression profiling along the intestinal crypt axis.. Mus musculus

The identification of Lgr5 as an intestinal stem cell marker has made it possible to isolate and study primary intestinal stem cells. Transcriptional differences between intestinal stem cells can be explored by the use of the Lgr5-eGFP-ires-CreERT2 knock-in mouse. In this mouse model GFP expression is driven from the Lgr5 locus, leading to highest GFP levels in the Lgr5 positive cells. Yet, due to the stability of the GFP protein, it is distributed upon cell division to the daughter cells. Here we arbitrarily sorted crypt cells based on GFP expression into five fractions. The fraction with the lowest GFP level is named 1+, the fraction with the highest level 5+. Overall design: We used cell fractions of intestines from Lgr5-EGFP-ires-CreERT2 mice, expressing GFP under the control of the Lgr5 promoter. RNA was isolated from five FACS sorted cell populations, with fraction 5+ expressing GFP at highest levels and 1+ expressing GFP at lowest levels. Differentially labelled cRNA from fractions 1+ to 4+ were hybridized against fraction 5+ on 4X44K Agilent Whole Mouse Genome dual colour Microarrays (G4122F) in dye swap experiments, resulting in eight individual arrays.