Canonical Notch signaling in the developing lung is required for determination of arterial smooth muscle cells and selection of Clara versus ciliated cell fate

Department of Developmental Biology and Division of Dermatology, Washington University School of Medicine, Box 8103, Saint Louis, MO 63110-1095, USA.
Journal of Cell Science (Impact Factor: 5.43). 01/2010; 123(Pt 2):213-24. DOI: 10.1242/jcs.058669
Source: PubMed


Lung development is the result of complex interactions between four tissues: epithelium, mesenchyme, mesothelium and endothelium. We marked the lineages experiencing Notch1 activation in these four cellular compartments during lung development and complemented this analysis by comparing the cell fate choices made in the absence of RBPjkappa, the essential DNA binding partner of all Notch receptors. In the mesenchyme, RBPjkappa was required for the recruitment and specification of arterial vascular smooth muscle cells (vSMC) and for regulating mesothelial epithelial-mesenchymal transition (EMT), but no adverse affects were observed in mice lacking mesenchymal RBPjkappa. We provide indirect evidence that this is due to vSMC rescue by endothelial-mesenchymal transition (EnMT). In the epithelium, we show that Notch1 activation was most probably induced by Foxj1-expressing cells, which suggests that Notch1-mediated lateral inhibition regulates the selection of Clara cells at the expense of ciliated cells. Unexpectedly, and in contrast to Pofut1-null epithelium, Hes1 expression was only marginally reduced in RBPjkappa-null epithelium, with a corresponding minimal effect on pulmonary neuroendocrine cell fate selection. Collectively, the primary roles for canonical Notch signaling in lung development are in selection of Clara cell fate and in vSMC recruitment. These analyses suggest that the impact of gamma-secretase inhibitors on branching in vitro reflect a non-cell autonomous contribution from endothelial or vSMC-derived signals.

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Available from: Zhenyi Liu, Jul 06, 2014
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    • "Notch signaling has an essential role in specification of CCs during lung development [9], [10], [11], [12]. Lineage analysis has shown that airway progenitors that activate Notch signaling during development adopt a CC fate [10]. "
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    ABSTRACT: Clara cells (CCs) are a morphologically and operationally heterogeneous population of Secretoglobin Scgb1a1-expressing secretory cells that are crucial for airway homeostasis and post-injury repair. Analysis of the extent and origin of CC diversity are limited by knowledge of genes expressed in these cells and their precursors. To identify novel putative markers of CCs and explore the origins of CC diversity, we characterized global changes in gene expression in embryonic lungs in which CCs do not form due to conditional disruption of Notch signaling (Rbpjk(CNULL)). Microarray profiling, Real Time PCR (qRT-PCR), and RNA in situ hybridization (ISH) identified eleven genes downregulated in the E18.5 airways of Rbpjk(cnull) compared to controls, nearly half not previously known to mark CCs. ISH revealed that several genes had overlapping but distinct domains of expression of in the normal developing lung (E18.5). Notably, Reg3g, Chad, Gabrp and Lrrc26 were enriched in proximal airways, Hp in the distal airways and Upk3a in clusters of cells surrounding Neuroepithelial Bodies (NEBs). Seven of the eleven genes, including Reg3g, Hp, and Upk3a, were expressed in the adult lung in CCs in a pattern similar to that observed in the developing airways. qRT-PCR-based analysis of gene expression of CCs isolated from different airway regions of B1-EGFP reporter mice corroborated the spatial enrichment in gene expression observed by ISH. Our study identifies candidate markers for CC-precursors and CCs and supports the idea that the diversification of the CC phenotype occurs already during embryonic development.
    PLoS ONE 02/2014; 9(2):e88848. DOI:10.1371/journal.pone.0088848 · 3.23 Impact Factor
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    • "Recently, a pathway that controls MCC development was identified in mouse airway epithelium and X. laevis epidermis. Downregulation of Notch signaling in MCC precursor cells (Tsao et al., 2009; Morimoto et al., 2010) leads to induction of multicilin (Mcin; Mcidas - Mouse Genome Informatics), which functions upstream of centriole amplification and induction of Foxj1 (Stubbs et al., 2012). Although MCIN expression is necessary and sufficient for MCC formation (Stubbs et al., 2012), how this novel nuclear protein controls centriole amplification and later steps in the multiciliogenesis program is not known. "
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    ABSTRACT: The transcriptional control of primary cilium formation and ciliary motility are beginning to be understood, but little is known about the transcriptional programs that control cilium number and other structural and functional specializations. One of the most intriguing ciliary specializations occurs in multiciliated cells (MCCs), which amplify their centrioles to nucleate hundreds of cilia per cell, instead of the usual monocilium. Here we report that the transcription factor MYB, which promotes S phase and drives cycling of a variety of progenitor cells, is expressed in postmitotic epithelial cells of the mouse airways and ependyma destined to become MCCs. MYB is expressed early in multiciliogenesis, as progenitors exit the cell cycle and amplify their centrioles, then switches off as MCCs mature. Conditional inactivation of Myb in the developing airways blocks or delays centriole amplification and expression of FOXJ1, a transcription factor that controls centriole docking and ciliary motility, and airways fail to become fully ciliated. We provide evidence that MYB acts in a conserved pathway downstream of Notch signaling and multicilin, a protein related to the S-phase regulator geminin, and upstream of FOXJ1. MYB can activate endogenous Foxj1 expression and stimulate a cotransfected Foxj1 reporter in heterologous cells, and it can drive the complete multiciliogenesis program in Xenopus embryonic epidermis. We conclude that MYB has an early, crucial and conserved role in multiciliogenesis, and propose that it promotes a novel S-like phase in which centriole amplification occurs uncoupled from DNA synthesis, and then drives later steps of multiciliogenesis through induction of Foxj1.
    Development 09/2013; 140(20). DOI:10.1242/dev.094102 · 6.46 Impact Factor
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    • "While healthy mesothelia in the adult appear uniform and innocuous, this cell type is actually highly plastic in nature performing multiple and varied functions in the embryo and adult. During organogenesis, mesothelia undergo epithelial mesenchymal transition (EMT) to provide all or nearly all vasculogenic cells in the generation of blood vessels as well as producing diverse stromal cells to internal organs [1], [2], [3], [4], [5], [6]. In the adult, mesothelia can undergo EMT generating cells critical in tissue repair while over-population of these cells in scaring and fibrosis in the heart, lung, and abdominal organs presents a major health problem [7], [8], [9], [10]. "
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    ABSTRACT: Mesothelia, which cover all coelomic organs and body cavities in vertebrates, perform diverse functions in embryonic and adult life. Yet, mesothelia are traditionally viewed as simple, uniform epithelia. Here we demonstrate distinct differences between visceral and parietal mesothelia, the most basic subdivision of this tissue type, in terms of gene expression, adhesion, migration, and invasion. Gene profiling determined that autotaxin, a secreted lysophospholipase D originally discovered as a tumor cell-motility-stimulating factor, was expressed exclusively in the more motile and invasive visceral mesothelia and at abnormally high levels in mesotheliomas. Gain and loss of function studies demonstrate that autotaxin signaling is indeed a critical factor responsible for phenotypic differences within mesothelia. Furthermore, we demonstrate that known and novel small molecule inhibitors of the autotaxin signaling pathway dramatically blunt migratory and invasive behaviors of aggressive mesotheliomas. Taken together, this study reveals distinct phenotypes within the mesothelial cell lineage, demonstrates that differential autotaxin expression is the molecular underpinning for these differences, and provides a novel target and lead compounds to intervene in invasive mesotheliomas.
    PLoS ONE 07/2013; 8(7):e69712. DOI:10.1371/journal.pone.0069712 · 3.23 Impact Factor
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