Candidate markers for stem and early progenitor cells, Musashi-1 and Hes1, are expressed in crypt base columnar cells of mouse small intestine.

Musashi-1, a neural RNA-binding protein, is important for maintaining neural stem cells. Both Musashi-1 and Hes1, a transcriptional factor regulated by Musashi-1, are expressed in the small intestine. Here we show that Musashi-1 is present in a few epithelial cells just above the Paneth cells in the small intestinal crypt, the putative position of stem cells, whereas Hes1 is expressed in lower crypt cells just above the Paneth cells, including Musashi-1-positive cells. Musashi-1 and Hes1 were not expressed in Paneth cells. Notably, Musashi-1 and Hes1 were coexpressed in the crypt base columnar cells located between the Paneth cells. These findings suggest that not only the cells just above Paneth cells but also the crypt base columnar cells between the Paneth cells have stem cell characteristics.