Dlx3 Regulates Lifr and Chrdl1 Expression in Mouse Embryonic Stem Cell Differentiation

Dlx3 over-expression in mouse embryonic fibroblasts changed the expression level of numerous genes involved in osteogenesis and embryonic stem cell-related pathways as revealed by microarray analysis. From the list of Dlx3 modulated genes we focused our attention on the study of two candidates, Lifr and Chrdl1. Chromatin immunoprecipitation demonstrated the recruitment of Dlx3 transcription factor to the promoters of Lifr and Chrdl1, and luciferase assays confirmed the role of Dlx3 in the regulation of Lifr expression. Over-expression of Dlx3 in mouse embryonic stem cells stimulated Lifr and Chrdl1 expression and inhibited expression of Id proteins and Bmp4. We show that Dlx3 increases the expression of both soluble and transmembrane forms of Lifr. Soluble Lifr may regulate extracellular Lif levels via solution binding, while transmembrane Lifr mediates the signal transduction pathway. The data suggests that Dlx3 may be involved in stem cell differentiation in a dosage dependent way through its interaction with Lifr and with Chrdl1, a known antagonist of Bmp4. We speculate that Dlx3 may also be involved in osteoblast differentiation through interactions involving Lifr, Bmp, and Id proteins and signaling via the JAK/STAT and MAPK pathways. In summary, our data suggests that Dlx3 proteins play a significant role in a highly tuned network in early embryogenesis. Keywords: treated vs.untreated Stable and Transient transfection of Dlx3 in MEF. Total of 4 hybridizations including biological replicates.