Sonic hedgehog signaling regulates Gli3 processing, mesenchymal proliferation, and differentiation during mouse lung organogenesis.
Lack of Sonic hedgehog (Shh) signaling, mediated by the Gli proteins, leads to severe pulmonary hypoplasia. However, the precise role of Gli genes in lung development is not well established. We show Shh signaling prevents Gli3 proteolysis to generate its repressor forms (Gli3R) in the developing murine lung. In Shh(-/-) or cyclopamine-treated wild-type (WT) lung, we found that Gli3R level is elevated, and this upregulation appears to contribute to defects in proliferation and differentiation observed in the Shh(-/-) mesenchyme, where Gli3 is normally expressed. In agreement, we found Shh(-/-);Gli3(-/-) lungs exhibit enhanced growth potential. Vasculogenesis is also enhanced; in contrast, bronchial myogenesis remains absent in Shh(-/-);Gli3(-/-) compared with Shh(-/-) lungs. Genes upregulated in Shh(-/-);Gli3(-/-) relative to Shh(-/-) lung include Wnt2 and, surprisingly, Foxf1 whose expression has been reported to be Shh-dependent. Cyclins D1, D2, and D3 antibody labelings also reveal distinct expression patterns in the normal and mutant lungs. We found significant repression of Tbx2 and Tbx3, both linked to inhibition of cellular senescence, in Shh(-/-) and partial derepression in Shh(-/-); Gli3(-/-) lungs, while Tbx4 and Tbx5 expressions are less affected in the mutants. Our findings shed light on the role of Shh signaling on Gli3 processing in lung growth and differentiation by regulating several critical genes.
Li
Yina
Y
Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232-8240, USA.
Zhang
Huimin
H
Choi
Seung Cheol
SC
Litingtung
Ying
Y
Chiang
Chin
C
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D046508:Culture Techniques; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D051858:Forkhead Transcription Factors; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D053823:Hedgehog Proteins; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D008168:Lung / Q000033:anatomy & histology / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014704:Veratrum Alkaloids / Q000494:pharmacology; D051153:Wnt Proteins; D051154:Wnt2 Protein; D029961:Zebrafish Proteins; D000074290:Zinc Finger Protein Gli3
D016213:Cyclins; D004268:DNA-Binding Proteins; C098521:FOXF1 protein, human; D051858:Forkhead Transcription Factors; C486293:Foxf1 protein, mouse; C465571:Gli3 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; C465570:Shh protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D014704:Veratrum Alkaloids; C495244:WNT2 protein, human; D051153:Wnt Proteins; D051154:Wnt2 Protein; D029961:Zebrafish Proteins; D000074290:Zinc Finger Protein Gli3; C000541:cyclopamine