Effect of chemical stabilizers of hypoxia-inducible factors on early lung development

2007 ◽  
Vol 293 (3) ◽  
pp. L557-L567 ◽  
Author(s):  
Freek A. Groenman ◽  
Martin Rutter ◽  
Jinxia Wang ◽  
Isabella Caniggia ◽  
Dick Tibboel ◽  
...  
Keyword(s):  
Lung Development ◽  
Hypoxia Inducible Factor ◽  
Iron Chelator ◽  
Branching Morphogenesis ◽  
Vegf Receptor ◽  
Low Oxygen ◽  
Prolyl Hydroxylases ◽  
Protein Levels ◽  
Terminal Buds ◽  
Airway Branching

Low oxygen stimulates pulmonary vascular development and airway branching and involves hypoxia-inducible factor (HIF). HIF is stable and initiates expression of angiogenic factors under hypoxia, whereas normoxia triggers hydroxylation of the HIF-1α subunit by prolyl hydroxylases (PHDs) and subsequent degradation. Herein, we investigated whether chemical stabilization of HIF-1α under normoxic (20% O2) conditions would stimulate vascular growth and branching morphogenesis in early lung explants. Tie2-LacZ (endothelial LacZ marker) mice were used for visualization of the vasculature. Embryonic day 11.5 (E11.5) lung buds were dissected and cultured in 20% O2 in the absence or presence of cobalt chloride (CoCl2, a hypoxia mimetic), dimethyloxalylglycine (DMOG; a nonspecific inhibitor of PHDs), or desferrioxamine (DFO; an iron chelator). Vascularization was assessed by X-gal staining, and terminal buds were counted. The fine vascular network surrounding the developing lung buds seen in control explants disappeared in CoCl2- and DFO-treated explants. Also, epithelial branching was reduced in the explants treated with CoCl2 and DFO. In contrast, DMOG inhibited branching but stimulated vascularization. Both DFO and DMOG increased nuclear HIF-1α protein levels, whereas CoCl2 had no effect. Since HIF-1α induces VEGF expression, the effect of SU-5416, a potent VEGF receptor (VEGFR) blocker, on early lung development was also investigated. Inhibition of VEGFR2 signaling in explants maintained under hypoxic (2% O2) conditions completely abolished vascularization and slightly decreased epithelial branching. Taken together, the data suggest that DMOG stabilization of HIF-1α during early development leads to a hypervascular lung and that airway branching proceeds without the vasculature, albeit at a slower rate.

Abrogation of mesenchyme-specific TGF-β signaling results in lung malformation with prenatal pulmonary cysts in mice

2021 ◽  
Author(s):  
Qing Miao ◽  
Hui Chen ◽  
Yongfeng Luo ◽  
Joanne Chiu ◽  
Ling Chu ◽  
...  
Keyword(s):  
Lung Development ◽  
Muscle Growth ◽  
Branching Morphogenesis ◽  
Mouse Lung ◽  
Cystic Lesions ◽  
Alveolar Epithelial ◽  
Pulmonary Cysts ◽  
Β Receptor ◽  
Airway Branching

The TGF-β signaling pathway plays a pivotal role in controlling organogenesis during fetal development. Although the role of TGF-β signaling in promoting lung alveolar epithelial growth has been determined, mesenchymal TGF-β signaling in regulating lung development has not been studied in vivo due to a lack of genetic tools for specifically manipulating gene expression in lung mesenchymal cells. Therefore, the integral roles of TGF-β signaling in regulating lung development and congenital lung diseases are not completely understood. Using a Tbx4 lung enhancer-driven Tet-On inducible Cre transgenic mouse system, we have developed a mouse model in which lung mesenchyme-specific deletion of TGF-β receptor 2 gene (Tgfbr2) is achieved. Reduced airway branching accompanied by defective airway smooth muscle growth and later peripheral cystic lesions occurred when lung mesenchymal Tgfbr2 was deleted from embryonic day 13.5 to 15.5, resulting in postnatal death due to respiratory insufficiency. Although cell proliferation in both lung epithelium and mesenchyme was reduced, epithelial differentiation was not significantly affected. Tgfbr2 downstream Smad-independent ERK1/2 may mediate these mesenchymal effects of TGF-β signaling through the GSK3β--β-catenin--Wnt canonical pathway in fetal mouse lung. Our study suggests that Tgfbr2-mediated TGF-β signaling in prenatal lung mesenchyme is essential for lung development and maturation, and defective TGF-β signaling in lung mesenchyme may be related to abnormal airway branching morphogenesis and congenital airway cystic lesions.

scholarly journals Crosstalk in oxygen homeostasis networks: SKN-1/NRF inhibits the HIF-1 hypoxia-inducible factor in Caenorhabditis elegans

2021 ◽  
Author(s):  
Dingxia Feng ◽  
Zhiwei Zhai ◽  
Zhiyong Shao ◽  
Yi Zhang ◽  
Jo Anne Powell-Coffman
Keyword(s):  
Oxidative Stress ◽  
Hypoxia Inducible Factor ◽  
Regulatory Sequences ◽  
Low Oxygen ◽  
Transcriptional Responses ◽  
C Elegans ◽  
Protein Levels ◽  
Oxygen Homeostasis ◽  
Genome Wide ◽  
A Genome

AbstractDuring development, homeostasis, and disease, organisms must balance responses that allow adaptation to low oxygen (hypoxia) with those that protect cells from oxidative stress. The evolutionarily conserved hypoxia-inducible factors are central to these processes, as they orchestrate transcriptional responses to oxygen deprivation. Here, we employ genetic strategies in C. elegans to identify stress-responsive genes and pathways that modulate the HIF-1 hypoxia-inducible factor and facilitate oxygen homeostasis. Through a genome-wide RNAi screen, we show that RNAi-mediated mitochondrial or proteasomal dysfunction increases the expression of hypoxia-responsive reporter Pnhr-57:GFP in C. elegans. Interestingly, only a subset of these effects requires hif-1. Of particular importance, we found that skn-1 RNAi increases the expression of hypoxia-responsive reporter Pnhr-57:GFP and elevates HIF-1 protein levels. The SKN-1/NRF transcription factor has been shown to promote oxidative stress resistance. We present evidence that the crosstalk between HIF-1 and SKN-1 is mediated by EGL-9, the prolyl hydroxylase that targets HIF-1 for oxygen-dependent degradation. Treatment that induces SKN-1, such as heat, increases expression of a Pegl-9:GFP reporter, and this effect requires skn-1 function and a putative SKN-1 binding site in egl-9 regulatory sequences. Collectively, these data support a model in which SKN-1 promotes egl-9 transcription, thereby inhibiting HIF-1. We propose that this interaction enables animals to adapt quickly to changes in cellular oxygenation and to better survive accompanying oxidative stress.

Regulation of retinoic acid signaling during lung morphogenesis

Development ◽  
2000 ◽  
Vol 127 (14) ◽  
pp. 3057-3067 ◽  
Author(s):  
S. Malpel ◽  
C. Mendelsohn ◽  
W.V. Cardoso
Keyword(s):  
Retinoic Acid ◽  
Lung Development ◽  
Branching Morphogenesis ◽  
Initial Stage ◽  
Signaling Center ◽  
Distal Lung ◽  
Immature Lung ◽  
Airway Branching ◽  
Correct Expression

Little is known about how retinoic acid (RA) synthesis, utilization and metabolism are regulated in the embryonic lung and how these activities relate to lung pattern formation. Here we report that early lung bud formation and subsequent branching morphogenesis are characterized by distinct stages of RA signaling. At the onset of lung development RA signaling is ubiquitously activated in primary buds, as shown by expression of the major RA-synthesizing enzyme, RALDH-2 and activation of a RARE-lacZ transgene. Nevertheless, further airway branching appears to require downregulation of RA pathways by decreased synthesis, increased RA degradation in the epithelium via P450RAI-mediated metabolism, and inhibition of RA signaling in the mesenchyme by COUPTF-II expression. These mechanisms controlling local RA signaling may be critical for normal branching, since we show that manipulating RA levels in vitro to maintain RA signaling activated as in the initial stage, leads to an immature lung phenotype characterized by failure to form typical distal buds. We show that this phenotype likely results from RA interfering with the establishment of a distal signaling center, altering levels and distribution of Fgf10 and Bmp4, genes that are essential for distal lung formation. Furthermore, RA upregulates P450RAI expression, suggesting the presence of feedback mechanisms controlling RA availability. Our study illustrates the importance of regional mechanisms that control RA availability and utilization for correct expression of pattern regulators and normal morphogenesis during lung development.

scholarly journals The chromatin remodeler ISWI regulates the cellular response to hypoxia: role of FIH

2011 ◽  
Vol 22 (21) ◽  
pp. 4171-4181 ◽  
Author(s):  
Andrew Melvin ◽  
Sharon Mudie ◽  
Sonia Rocha
Keyword(s):  
Rna Polymerase Ii ◽  
Chromatin Remodeling ◽  
Cellular Response ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Prolyl Hydroxylases ◽  
Additional Information ◽  
Protein Levels ◽  
Survival Factor

The hypoxia-inducible factor (HIF) is a master regulator of the cellular response to hypoxia. Its levels and activity are controlled by dioxygenases called prolyl-hydroxylases and factor inhibiting HIF (FIH). To activate genes, HIF has to access sequences in DNA that are integrated in chromatin. It is known that the chromatin-remodeling complex switch/sucrose nonfermentable (SWI/SNF) is essential for HIF activity. However, no additional information exists about the role of other chromatin-remodeling enzymes in hypoxia. Here we describe the role of imitation switch (ISWI) in the cellular response to hypoxia. We find that unlike SWI/SNF, ISWI depletion enhances HIF activity without altering its levels. Furthermore, ISWI knockdown only alters a subset of HIF target genes. Mechanistically, we find that ISWI is required for full expression of FIH mRNA and protein levels by changing RNA polymerase II loading to the FIH promoter. Of interest, exogenous FIH can rescue the ISWI-mediated upregulation of CA9 but not BNIP3, suggesting that FIH-independent mechanisms are also involved. Of importance, ISWI depletion alters the cellular response to hypoxia by reducing autophagy and increasing apoptosis. These results demonstrate a novel role for ISWI as a survival factor during the cellular response to hypoxia.

scholarly journals The Lung Vasculature: A Driver or Passenger in Lung Branching Morphogenesis?

2021 ◽  
Vol 8 ◽  
Author(s):  
Yelda Pakize Kina ◽  
Ali Khadim ◽  
Werner Seeger ◽  
Elie El Agha
Keyword(s):  
Lung Development ◽  
Branching Morphogenesis ◽  
Mouse Lung ◽  
Physical Factors ◽  
Airway Epithelial ◽  
Leading Role ◽  
Rate Limiting Step ◽  
Airway Tree ◽  
Rate Limiting ◽  
Airway Branching

Multiple cellular, biochemical, and physical factors converge to coordinate organogenesis. During embryonic development, several organs such as the lung, salivary glands, mammary glands, and kidneys undergo rapid, but intricate, iterative branching. This biological process not only determines the overall architecture, size and shape of such organs but is also a pre-requisite for optimal organ function. The lung, in particular, relies on a vast surface area to carry out efficient gas exchange, and it is logical to suggest that airway branching during lung development represents a rate-limiting step in this context. Against this background, the vascular network develops in parallel to the airway tree and reciprocal interaction between these two compartments is critical for their patterning, branching, and co-alignment. In this mini review, we present an overview of the branching process in the developing mouse lung and discuss whether the vasculature plays a leading role in the process of airway epithelial branching.

The RNA-binding protein Quaking regulates multiciliated and basal cell abundance in the developing lung

2021 ◽  
Author(s):  
Dustin Ameis ◽  
Franklin Liu ◽  
Eimear Kirby ◽  
Daywin Patel ◽  
Richard Keijzer
Keyword(s):  
Basal Cell ◽  
Lung Development ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Branching Morphogenesis ◽  
Lung Cells ◽  
Mrna Levels ◽  
Basal Cells ◽  
Protein Levels ◽  
Multiciliated Cells

RNA-binding proteins (RBPs) form complexes with RNA, changing how the RNA is processed and thereby regulating gene expression. RBPs are important sources of gene regulation during organogenesis, including the development of the lungs. The RBP called Quaking (QK) is critical for embryogenesis, yet has not been studied in the developing lung. Here, we show that QK is widely expressed during rat lung development and into adulthood. The QK isoforms QK5 and QK7 co-localize to the nuclei of nearly all lung cells. QK6 is present in the nuclei and cytoplasm of mesenchymal cells and is only present in the epithelium during branching morphogenesis. QK knockdown in embryonic lung explants caused a greater number of multiciliated cells to appear in the airways, at the expense of basal cells. The mRNA of multiciliated cell genes and the abundance of FOXJ1/SOX2+ cells increased after knockdown, while P63/SOX2+ cells decreased. The cytokine IL-6, a known regulator of multiciliated cell differentiation, had increased mRNA levels after QK knockdown, although protein levels remained unchanged. Further studies are necessary to confirm whether QK acts as a blocker for the IL-6 induced differentiation of basal cell into multiciliated cells, and a conditional QK knockout would likely lead to additional discoveries on QK's role during lung development.

scholarly journals Maternal high-fat diet alters lung development and function in the offspring

2019 ◽  
Vol 317 (2) ◽  
pp. L167-L174 ◽  
Author(s):  
Kathryn M. Heyob ◽  
Saya Mieth ◽  
Sophia S. Sugar ◽  
Amanda E. Graf ◽  
Scott W. Lallier ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
High Fat Diet ◽  
Lung Development ◽  
Maternal Obesity ◽  
Control Diet ◽  
Tyrosine Phosphatase ◽  
Vegf Receptor ◽  
High Fat ◽  
Lung Weight ◽  
Protein Levels

The effects of maternal obesity on lung development have been recognized, and speculation is that these diseases are not simply because of accelerated pulmonary decline with aging but with a failure to achieve optimal lung development during early life. These studies tested the hypothesis that maternal obesity alters signaling pathways during the course of lung development that may affect life-long pulmonary health. Adult female mice were fed 60% fat [high-fat diet (HFD)] or 10% fat [control diet (CD)] for 8 wk before mating and through weaning. Pup lung tissues were collected at postnatal days ( PN) 7, 21, and 90 (after receiving HFD or CD as adults). At PN7, body weights from HFD were greater than CD but lung weight-to-body weight ratios were lower. In lung tissues, NFκB-mediated inflammation was greater in HFD pups at PN21 and phospho-/total STAT3, phospho-/total VEGF receptor 2, and total AKT protein levels were lower with maternal HFD and protein tyrosine phosphatase B1 levels were increased. Decreased platelet endothelial cell adhesion molecule levels were observed at PN21 and at PN90 in the pups exposed to maternal HFD. Morphometry indicated that the pups exposed to maternal or adult HFD had fewer alveoli, and the effect was additive. Decreases in pulmonary resistance, elastance, and compliance were observed because of adult HFD diet and decreases in airway resistance and increases in inspiratory capacity because of maternal HFD. In conclusion, maternal HFD disrupts signaling pathways in the early developing lung and may contribute to deficiencies in lung function and increased susceptibility in adults.

Role of oxygen and vascular development in epithelial branching morphogenesis of the developing mouse lung

2005 ◽  
Vol 288 (1) ◽  
pp. L167-L178 ◽  
Author(s):  
Minke van Tuyl ◽  
Jason Liu ◽  
Jinxia Wang ◽  
Maciek Kuliszewski ◽  
Dick Tibboel ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Vascular Tissue ◽  
Vascular Development ◽  
Branching Morphogenesis ◽  
Mouse Lung ◽  
Vegf Receptor ◽  
Lacz Gene ◽  
Low Oxygen ◽  
Pulmonary Vascular Development

Recent investigations have suggested an active role for endothelial cells in organ development, including the lung. Herein, we investigated some of the molecular mechanisms underlying normal pulmonary vascular development and their influence on epithelial branching morphogenesis. Because the lung in utero develops in a relative hypoxic environment, we first investigated the influence of low oxygen on epithelial and vascular branching morphogenesis. Two transgenic mouse models, the C101-LacZ (epithelial-LacZ marker) and the Tie2-LacZ (endothelial-LacZ marker), were used. At embryonic day 11.5, primitive lung buds were dissected and cultured at either 20 or 3% oxygen. At 24-h intervals, epithelial and endothelial LacZ gene expression was visualized by X-galactosidase staining. The rate of branching of both tissue elements was increased in explants cultured at 3% oxygen compared with 20% oxygen. Low oxygen increased expression of VEGF, but not that of the VEGF receptor (Flk-1). Expression of two crucial epithelial branching factors, fibroblast growth factor-10 and bone morphogenetic protein-4, were not affected by low oxygen. Epithelial differentiation was maintained at low oxygen as shown by surfactant protein C in situ hybridization. To explore epithelial-vascular interactions, we inhibited vascular development with antisense oligonucleotides targeted against either hypoxia inducible factor-1α or VEGF. Epithelial branching morphogenesis in vitro was dramatically abrogated when pulmonary vascular development was inhibited. Collectively, the in vitro data show that a low-oxygen environment enhances branching of both distal lung epithelium and vascular tissue and that pulmonary vascular development appears to be rate limiting for epithelial branching morphogenesis.

scholarly journals Differential Responsiveness in VEGF Receptor Subtypes to Hypoxic Stress in Various Tissues of Plateau Animals

2017 ◽  
pp. 357-362 ◽  
Author(s):  
H.-C. XIE ◽  
J.-G. LI ◽  
J.-P. HE
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Hypoxia Inducible Factor ◽  
Receptor Subtypes ◽  
Vegf Receptor ◽  
Hypoxic Stress ◽  
Adaptive Responses ◽  
Sprague Dawley ◽  
Low Oxygen ◽  
Hypoxic Environment

With hypoxic stress, hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) are elevated and their responses are altered in skeletal muscles of plateau animals [China Qinghai-Tibetan plateau pikas (Ochotona curzoniae)] as compared with control animals [normal lowland Sprague-Dawley (SD) rats]. The results indicate that HIF-1α and VEGF are engaged in physiological functions under hypoxic environment. The purpose of the current study was to examine the protein levels of VEGF receptor subtypes (VEGFRs: VEGFR-1, VEGFR-2 and VEGFR-3) in the end organs, namely skeletal muscle, heart and lung in response to hypoxic stress. ELISA and Western blot analysis were employed to determine HIF-1α and the protein expression of VEGFRs in control animals and plateau pikas. We further blocked HIF-1α signal to determine if HIF-1α regulates alternations in VEGFRs in those tissues. We hypothesized that responsiveness of VEGFRs in the major end organs of plateau animals is differential with insult of hypoxic stress and is modulated by low oxygen sensitive HIF-1α. Our results show that hypoxic stress induced by exposure of lower O2 for 6 h significantly increased the levels of VEGFR-2 in skeletal muscle, heart and lung and the increases were amplified in plateau pikas. Our results also demonstrate that hypoxic stress enhanced VEGFR-3 in lungs of plateau animals. Nonetheless, no significant alternations in VEGFR-1 were observed in those tissues with hypoxic stress. Moreover, we observed decreases of VEGFR-2 in skeletal muscle, heart and lung; and decreases of VEGFR-3 in lung following HIF-1α inhibition. Overall, our findings suggest that in plateau animals 1) responsiveness of VEGFRs is different under hypoxic environment; 2) amplified VEGFR-2 response appears in skeletal muscle, heart and lung, and enhanced VEGFR-3 response is mainly observed in lung; 3) HIF-1α plays a regulatory role in the levels of VEGFRs. Our results provide the underlying cellular and molecular mechanisms responsible for hypoxic environment in plateau animals, having an impact on research of physiological and ecological adaptive responses to acute or chronic hypoxic stress in humans who living at high attitude and who live at a normal sea level but suffer from hypoxic disorders.

scholarly journals Placental but Not Heart Defects Are Associated with Elevated Hypoxia-Inducible Factor α Levels in Mice Lacking Prolyl Hydroxylase Domain Protein 2

2006 ◽  
Vol 26 (22) ◽  
pp. 8336-8346 ◽  
Author(s):  
Kotaro Takeda ◽  
Vivienne C. Ho ◽  
Hiromi Takeda ◽  
Li-Juan Duan ◽  
Andras Nagy ◽  
...  
Keyword(s):  
Heart Defects ◽  
Interventricular Septum ◽  
Hypoxia Inducible Factor ◽  
Giant Cells ◽  
Branching Morphogenesis ◽  
Mouse Development ◽  
Protein Levels ◽  
The Stability ◽  
Factor Α ◽  
Trophoblast Giant Cells

ABSTRACT PHD1, PHD2, and PHD3 are prolyl hydroxylase domain proteins that regulate the stability of hypoxia-inducible factor α subunits (HIF-α). To determine the roles of individual PHDs during mouse development, we disrupted all three Phd genes and found that Phd2 − / − embryos died between embryonic days 12.5 and 14.5 whereas Phd1 −/− or Phd3 −/− mice were apparently normal. In Phd2 − / − mice, severe placental and heart defects preceded embryonic death. Placental defects included significantly reduced labyrinthine branching morphogenesis, widespread penetration of the labyrinth by spongiotrophoblasts, and abnormal distribution of trophoblast giant cells. The expression of several trophoblast markers was also altered, including an increase in the spongiotrophoblast marker Mash2 and decreases in the labyrinthine markers Tfeb and Gcm1. In the heart, trabeculae were poorly developed, the myocardium was remarkably thinner, and interventricular septum was incompletely formed. Surprisingly, while there were significant global increases in HIF-α protein levels in the placenta and the embryo proper, there was no specific HIF-α increase in the heart. Taken together, these data indicate that among all three PHD proteins, PHD2 is uniquely essential during mouse embryogenesis.

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