Detection of EGF-dependent microRNAs of the fetal mouse submandibular gland at embryonic day 13

Fetal murine submandibular salivary gland (SMG) is known as a model to study organogenesis including branching morphogenesis, which is a basic developmental process for formation of a wide variety of arborized organs. Branching morphogenesis is under the control of a complex network of regulatory proteins, such as the ErbB family of tyrosine kinase receptors, activated by members of the epidermal growth factor (EGF) family of ligands. Recent reports identify critical roles for micro RNAs (miRNAs) on many developmental processes through regulation of gene expression. We hypothesize that miRNAs regulating branching morphogenesis are expressed in fetal murine SMG and that expression of the miRNAs associated with branching morphogenesis is modulated in part by EGF. Using cloning methods, we obtained the expression profiles on miRNAs derived from fetal murine SMG under three different conditions : (1) native E13 SMGs (freshly isolated), (2) E13 SMGs cultured for 24 hours with no added EGF (controls), or (3) cultured with EGF. There were 44 known miRNAs and four novel miRNAs candidates in native SMG at E13. Comparing the three profiles revealed that several miRNAs were expressed specifically at each condition. These results suggested that these miRNAs were associated with regulating organogenesis, possibly including branching morphogenesis.