Expression Profiling of the Developing Mouse Lung

Mammalian lung development is a complex morphogenetic process, which initiates near mid-gestation and continues through early postnatal life. The lung arises as two lateral buds that emerge from the ventral foregut endoderm at ~ 9 days after fertilization (in mouse) and undergo numerous rounds of dichotomous branching to form the bronchial tree. This stage of development is referred to as the pseudoglandular phase, histologically characterized by loose mesenchyme surrounding undifferentiated epithelial tubes. We have undertaken a comprehensive gene expression profiling of the entire process of murine lung development using oligonucleotide-based microarrays. Our data reveals the expression pattern of ~ 11,000 genes throughout the morphologic stages of lung development. Examination of the data confirms previously known patterns of expression for extracellular matrix genes and provides new information regarding relationships in temporal expression among groups of these genes. Large-scale cluster analysis reveals associations in the expression profile of specific genes with defined developmental processes. Keywords: time course RNA was isolated from individual (E18, P1, P4, P7, P10, P14, P21, and adult) or pooled (E12, E14, E16) whole lungs using a modified guanidinium:phenol extraction method.Ten micrograms of total RNA was used to generate target cRNA for hybridization to Affymetrix Mu11K chipset subA and subB oligonucleotide microarrays. A single chip set was used for each time-point. Before target generation, individual RNA samples were pooled so that each target was derived from a minimum of three individual lungs.