TABLE 2.
GENES HIGHLY EXPRESSED IN THE DISTAL LUNG EPITHELIAL PROGENITOR CELLS
| Gene | Description | Roles in Progenitor Cells | References |
|---|---|---|---|
| Foxp1, Foxp2 | Transcription factors | Partially redundant; possibly required for progenitor cell self-renewal through regulation of Nmyc. | (21) |
| Id2 | Transcription factor | No reported lung phenotype. | (7) |
| Nmyc | Transcription factor | Promotes distal epithelial cell self-renewal and inhibits differentiation. | (5) |
| Sox9 | Transcription factor | Lung epithelial specific knockouts have no phenotype. | (7, 22) |
| BMP4 | Signaling molecule | Required to promote distal epithelial cell proliferation and maintain cell morphology. | (23) |
| Elf5 | Transcription factor | Downstream of Fgf signaling. Mutants have no reported lung phenotype. | (46) |
| Etv5 | Transcription factor | Downstream of Fgf signaling. Promotes epithelial cell differentiation and inhibits proliferation. | (7, 47) |
| Spry2 | Inhibitor of Fgf signaling | Overexpression inhibits branching morphogenesis and epithelial proliferation. | (48) |
| Shh | Signaling molecule | Required for epithelial and mesenchymal proliferation, branching morphogenesis, and mesenchymal differentiation. | (25) |
| Wnt7b | Signaling molecule | Promotes mesenchymal proliferation. | (49) |
| Wnt5a | Signaling molecule | Mutants have one extra branch of conducting airways; effect on progenitors unclear. | (26) |
| Dkk1 | Inhibitor of Wnt signaling | Inhibits branching in in vitro culture. | (50) |
| Notch1 | Signaling molecule | Not investigated in vivo. | (33) |
| Thbs1 | Extracellular calcium binding protein | No embryonic lung phenotype. | (7) |