1
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Su Y, Barr J, Jaquish A, Xu J, Verheyden JM, Sun X. Identification of lung innervating sensory neurons and their target specificity. Am J Physiol Lung Cell Mol Physiol 2022; 322:L50-L63. [PMID: 34755535 PMCID: PMC8721910 DOI: 10.1152/ajplung.00376.2021] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Known as the gas exchange organ, the lung is also critical for responding to the aerosol environment in part through interaction with the nervous system. The diversity and specificity of lung innervating neurons remain poorly understood. Here, we interrogated the cell body location and molecular signature and projection pattern of lung innervating sensory neurons. Retrograde tracing from the lung coupled with whole tissue clearing highlighted neurons primarily in the vagal ganglia. Centrally, they project specifically to the nucleus of the solitary tract in the brainstem. Peripherally, they enter the lung alongside branching airways. Labeling of nociceptor Trpv1+ versus peptidergic Tac1+ vagal neurons showed shared and distinct terminal morphology and targeting to airway smooth muscles, vasculature including lymphatics, and alveoli. Notably, a small population of vagal neurons that are Calb1+ preferentially innervate pulmonary neuroendocrine cells, a demonstrated airway sensor population. This atlas of lung innervating neurons serves as a foundation for understanding their function in lung.
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Affiliation(s)
- Yujuan Su
- 1Department of Pediatrics, University of California, San Diego, California
| | - Justinn Barr
- 1Department of Pediatrics, University of California, San Diego, California
| | - Abigail Jaquish
- 1Department of Pediatrics, University of California, San Diego, California
| | - Jinhao Xu
- 1Department of Pediatrics, University of California, San Diego, California
| | - Jamie M. Verheyden
- 1Department of Pediatrics, University of California, San Diego, California
| | - Xin Sun
- 1Department of Pediatrics, University of California, San Diego, California,2Division of Biological Sciences, University of California, San Diego, California
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2
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Wang A, Chiou J, Poirion OB, Buchanan J, Valdez MJ, Verheyden JM, Hou X, Kudtarkar P, Narendra S, Newsome JM, Guo M, Faddah DA, Zhang K, Young RE, Barr J, Sajti E, Misra R, Huyck H, Rogers L, Poole C, Whitsett JA, Pryhuber G, Xu Y, Gaulton KJ, Preissl S, Sun X. Single-cell multiomic profiling of human lungs reveals cell-type-specific and age-dynamic control of SARS-CoV2 host genes. eLife 2020; 9:e62522. [PMID: 33164753 PMCID: PMC7688309 DOI: 10.7554/elife.62522] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 11/08/2020] [Indexed: 12/12/2022] Open
Abstract
Respiratory failure associated with COVID-19 has placed focus on the lungs. Here, we present single-nucleus accessible chromatin profiles of 90,980 nuclei and matched single-nucleus transcriptomes of 46,500 nuclei in non-diseased lungs from donors of ~30 weeks gestation,~3 years and ~30 years. We mapped candidate cis-regulatory elements (cCREs) and linked them to putative target genes. We identified distal cCREs with age-increased activity linked to SARS-CoV-2 host entry gene TMPRSS2 in alveolar type 2 cells, which had immune regulatory signatures and harbored variants associated with respiratory traits. At the 3p21.31 COVID-19 risk locus, a candidate variant overlapped a distal cCRE linked to SLC6A20, a gene expressed in alveolar cells and with known functional association with the SARS-CoV-2 receptor ACE2. Our findings provide insight into regulatory logic underlying genes implicated in COVID-19 in individual lung cell types across age. More broadly, these datasets will facilitate interpretation of risk loci for lung diseases.
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Affiliation(s)
- Allen Wang
- Center for Epigenomics & Department of Cellular & Molecular Medicine, University of California, San DiegoSan DiegoUnited States
| | - Joshua Chiou
- Biomedical Sciences Graduate Program, University of California San DiegoLa JollaUnited States
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Olivier B Poirion
- Center for Epigenomics & Department of Cellular & Molecular Medicine, University of California, San DiegoSan DiegoUnited States
| | - Justin Buchanan
- Center for Epigenomics & Department of Cellular & Molecular Medicine, University of California, San DiegoSan DiegoUnited States
| | - Michael J Valdez
- Biomedical Sciences Graduate Program, University of California San DiegoLa JollaUnited States
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Jamie M Verheyden
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Xiaomeng Hou
- Center for Epigenomics & Department of Cellular & Molecular Medicine, University of California, San DiegoSan DiegoUnited States
| | - Parul Kudtarkar
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Sharvari Narendra
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Jacklyn M Newsome
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Minzhe Guo
- Division of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children's Hospital Medical CenterCincinnatiUnited States
- Divisions of Pulmonary Biology and Biomedical Informatics, University of Cincinnati College of MedicineCincinnatiUnited States
| | | | - Kai Zhang
- Ludwig Institute for Cancer ResearchLa JollaUnited States
| | - Randee E Young
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-MadisonMadisonUnited States
| | - Justinn Barr
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Eniko Sajti
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Ravi Misra
- Department of Pediatrics and Clinical & Translational Science Institute, University of Rochester Medical CenterRochesterUnited States
| | - Heidie Huyck
- Department of Pediatrics and Clinical & Translational Science Institute, University of Rochester Medical CenterRochesterUnited States
| | - Lisa Rogers
- Department of Pediatrics and Clinical & Translational Science Institute, University of Rochester Medical CenterRochesterUnited States
| | - Cory Poole
- Department of Pediatrics and Clinical & Translational Science Institute, University of Rochester Medical CenterRochesterUnited States
| | - Jeffery A Whitsett
- Division of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children's Hospital Medical CenterCincinnatiUnited States
- Divisions of Pulmonary Biology and Biomedical Informatics, University of Cincinnati College of MedicineCincinnatiUnited States
| | - Gloria Pryhuber
- Department of Pediatrics and Clinical & Translational Science Institute, University of Rochester Medical CenterRochesterUnited States
| | - Yan Xu
- Division of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children's Hospital Medical CenterCincinnatiUnited States
- Divisions of Pulmonary Biology and Biomedical Informatics, University of Cincinnati College of MedicineCincinnatiUnited States
| | - Kyle J Gaulton
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
| | - Sebastian Preissl
- Center for Epigenomics & Department of Cellular & Molecular Medicine, University of California, San DiegoSan DiegoUnited States
| | - Xin Sun
- Department of Pediatrics, University of California-San DiegoLa JollaUnited States
- Department of Biological Sciences, University of California-San DiegoLa JollaUnited States
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3
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Affiliation(s)
- Jamie M Verheyden
- Department of Pediatrics, University of California, San Diego, San Diego, CA, USA
| | - Xin Sun
- Department of Pediatrics, University of California, San Diego, San Diego, CA, USA. .,Department of Biological Sciences, University of California, San Diego, San Diego, CA, USA.
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4
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Young RE, Jones MK, Hines EA, Li R, Luo Y, Shi W, Verheyden JM, Sun X. Smooth Muscle Differentiation Is Essential for Airway Size, Tracheal Cartilage Segmentation, but Dispensable for Epithelial Branching. Dev Cell 2020; 53:73-85.e5. [PMID: 32142630 PMCID: PMC7540204 DOI: 10.1016/j.devcel.2020.02.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 12/10/2019] [Accepted: 01/31/2020] [Indexed: 01/11/2023]
Abstract
Airway smooth muscle is best known for its role as an airway constrictor in diseases such as asthma. However, its function in lung development is debated. A prevalent model, supported by in vitro data, posits that airway smooth muscle promotes lung branching through peristalsis and pushing intraluminal fluid to branching tips. Here, we test this model in vivo by inactivating Myocardin, which prevented airway smooth muscle differentiation. We found that Myocardin mutants show normal branching, despite the absence of peristalsis. In contrast, tracheal cartilage, vasculature, and neural innervation patterns were all disrupted. Furthermore, airway diameter is reduced in the mutant, counter to the expectation that the absence of smooth muscle constriction would lead to a more relaxed and thereby wider airway. These findings together demonstrate that during development, while airway smooth muscle is dispensable for epithelial branching, it is integral for building the tracheal architecture and promoting airway growth.
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Affiliation(s)
- Randee E Young
- Department of Pediatrics, University of California-San Diego, La Jolla, CA 92093, USA; Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Mary-Kayt Jones
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Elizabeth A Hines
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Rongbo Li
- Department of Pediatrics, University of California-San Diego, La Jolla, CA 92093, USA
| | - Yongfeng Luo
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Wei Shi
- Developmental Biology and Regenerative Medicine Program, Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Jamie M Verheyden
- Department of Pediatrics, University of California-San Diego, La Jolla, CA 92093, USA.
| | - Xin Sun
- Department of Pediatrics, University of California-San Diego, La Jolla, CA 92093, USA; Department of Biological Sciences, University of California-San Diego, La Jolla, CA 92093, USA.
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5
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Sui P, Li R, Zhang Y, Tan C, Garg A, Verheyden JM, Sun X. E3 ubiquitin ligase MDM2 acts through p53 to control respiratory progenitor cell number and lung size. Development 2019; 146:dev.179820. [PMID: 31767619 DOI: 10.1242/dev.179820] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 11/18/2019] [Indexed: 12/21/2022]
Abstract
The respiratory lineage initiates from the specification of NKX2-1+ progenitor cells that ultimately give rise to a vast gas-exchange surface area. How the size of the progenitor pool is determined and whether this directly impacts final lung size remains poorly understood. Here, we show that epithelium-specific inactivation of Mdm2, which encodes an E3 ubiquitin ligase, led to lethality at birth with a striking reduction of lung size to a single vestigial lobe. Intriguingly, this lobe was patterned and contained all the appropriate epithelial cell types. The reduction of size can be traced to the progenitor stage, when p53, a principal MDM2 protein degradation target, was transiently upregulated. This was followed by a brief increase of apoptosis. Inactivation of the p53 gene in the Mdm2 mutant background effectively reversed the lung size phenotype, allowing survival at birth. Together, these findings demonstrate that p53 protein turnover by MDM2 is essential for the survival of respiratory progenitors. Unlike in the liver, in which genetic reduction of progenitors triggered compensation, in the lung, respiratory progenitor number is a key determinant factor for final lung size.
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Affiliation(s)
- Pengfei Sui
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA.,Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA.,Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200231, China
| | - Rongbo Li
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA.,Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
| | - Yan Zhang
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA.,Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
| | - Chunting Tan
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA
| | - Ankur Garg
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA
| | - Jamie M Verheyden
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA .,Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
| | - Xin Sun
- Department of Pediatrics, Department of Biological Sciences, University of California, San Diego, CA 92130, USA .,Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
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6
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Hines EA, Jones MKN, Harvey JF, Perlyn C, Ornitz DM, Sun X, Verheyden JM. Crouzon syndrome mouse model exhibits cartilage hyperproliferation and defective segmentation in the developing trachea. Sci China Life Sci 2019; 62:1375-1380. [PMID: 31463736 DOI: 10.1007/s11427-019-9568-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 05/16/2019] [Indexed: 12/30/2022]
Abstract
Crouzon syndrome is the result of a gain-of-function point mutation in FGFR2. Mimicking the human mutation, a mouse model of Crouzon syndrome (Fgfr2342Y) recapitulates patient deformities, including failed tracheal cartilage segmentation, resulting in a cartilaginous sleeve in the homozygous mutants. We found that the Fgfr2C342Y/C342Y mutants exhibited an increase in chondrocytes prior to segmentation. This increase is due at least in part to over proliferation. Genetic ablation of chondrocytes in the mutant led to restoration of segmentation in the lateral but not central portion of the trachea. These results suggest that in the Fgfr2C342Y/C342Y mutants, increased cartilage cell proliferation precedes and contributes to the disruption of cartilage segmentation in the developing trachea.
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Affiliation(s)
- Elizabeth A Hines
- Laboratory of Genetics, University of Wisconsin, Madison, WI, 53706, USA
| | - Mary-Kayt N Jones
- Laboratory of Genetics, University of Wisconsin, Madison, WI, 53706, USA
| | - Julie F Harvey
- Laboratory of Genetics, University of Wisconsin, Madison, WI, 53706, USA
| | - Chad Perlyn
- Department of Surgery, Florida International University College of Medicine, Miami, FL, 33199, USA
| | - David M Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin, Madison, WI, 53706, USA. .,Department of Pediatrics, University of California-San Diego, La Jolla, CA, 92093, USA.
| | - Jamie M Verheyden
- Laboratory of Genetics, University of Wisconsin, Madison, WI, 53706, USA. .,Department of Pediatrics, University of California-San Diego, La Jolla, CA, 92093, USA.
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7
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Abstract
While the lung is commonly known for its gas exchange function, it is exposed to signals in the inhaled air and responds to them by collaborating with other systems including immune cells and the neural circuit. This important aspect of lung physiology led us to consider the lung as a sensory organ. Among different cell types within the lung that mediate this role, several recent studies have renewed attention on pulmonary neuroendocrine cells (PNECs). PNECs are a rare, innervated airway epithelial cell type that accounts for <1% of the lung epithelium population. They are enriched at airway branch points. Classical in vitro studies have shown that PNECs can respond to an array of aerosol stimuli such as hypoxia, hypercapnia and nicotine. Recent in vivo evidence suggests an essential role of PNECs at neuroimmunomodulatory sites of action, releasing neuropeptides, neurotransmitters and facilitating asthmatic responses to allergen. In addition, evidence supports that PNECs can function both as progenitor cells and progenitor niches following airway epithelial injury. Increases in PNECs have been documented in a large array of chronic lung diseases. They are also the cells-of-origin for small cell lung cancer. A better understanding of the specificity of their responses to distinct insults, their impact on normal lung function and their roles in the pathogenesis of pulmonary ailments will be the next challenge toward designing therapeutics targeting the neuroendocrine system in lung.
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Affiliation(s)
- Ankur Garg
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States
| | - Pengfei Sui
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States
| | - Jamie M Verheyden
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States
| | - Lisa R Young
- Division of Pulmonary Medicine, Center for Childhood Lung Research, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Xin Sun
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States; Department of Biological Sciences, University of California, San Diego, La Jolla, CA, United States.
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8
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Nantie LB, Young RE, Paltzer WG, Zhang Y, Johnson RL, Verheyden JM, Sun X. Lats1/2 inactivation reveals Hippo function in alveolar type I cell differentiation during lung transition to air breathing. Development 2018; 145:dev.163105. [PMID: 30305289 DOI: 10.1242/dev.163105] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 10/03/2018] [Indexed: 12/21/2022]
Abstract
Lung growth to its optimal size at birth is driven by reiterative airway branching followed by differentiation and expansion of alveolar cell types. How this elaborate growth is coordinated with the constraint of the chest is poorly understood. Here, we investigate the role of Hippo signaling, a cardinal pathway in organ size control, in mouse lung development. Unexpectedly, we found that epithelial loss of the Hippo kinase genes Lats1 and Lats2 (Lats1/2) leads to a striking reduction of lung size owing to an early arrest of branching morphogenesis. This growth defect is accompanied by abnormalities in epithelial cell polarity, cell division plane and extracellular matrix deposition, as well as precocious and increased expression of markers for type 1 alveolar epithelial cells (AEC1s), an indicator of terminal differentiation. Increased AEC1s were also observed in transgenic mice with overexpression of a constitutive nuclear form of downstream transcriptional effector YAP. Conversely, loss of Yap and Taz led to decreased AEC1s, demonstrating that the canonical Hippo signaling pathway is both sufficient and necessary to drive AEC1 fate. These findings together reveal unique roles of Hippo-LATS-YAP signaling in the developing mouse lung.
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Affiliation(s)
- Leah B Nantie
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Randee E Young
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.,Department of Pediatrics, Department of Biological Sciences, University of California-San Diego, La Jolla, CA 92093, USA
| | - Wyatt G Paltzer
- Department of Pediatrics, Department of Biological Sciences, University of California-San Diego, La Jolla, CA 92093, USA
| | - Yan Zhang
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.,Department of Pediatrics, Department of Biological Sciences, University of California-San Diego, La Jolla, CA 92093, USA
| | - Randy L Johnson
- Department of Cancer Biology, University of Texas, MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jamie M Verheyden
- Department of Pediatrics, Department of Biological Sciences, University of California-San Diego, La Jolla, CA 92093, USA
| | - Xin Sun
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA .,Department of Pediatrics, Department of Biological Sciences, University of California-San Diego, La Jolla, CA 92093, USA
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9
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Lungova V, Verheyden JM, Sun X, Thibeault SL. β-Catenin signaling is essential for mammalian larynx recanalization and the establishment of vocal fold progenitor cells. Development 2018; 145:dev.157677. [PMID: 29386246 DOI: 10.1242/dev.157677] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 01/18/2018] [Indexed: 02/01/2023]
Abstract
Congenital laryngeal webs result from failure of vocal fold separation during development in utero Infants present with life-threatening respiratory problems at birth, and extensive lifelong difficulties in breathing and voicing. The molecular mechanisms that instruct vocal fold formation are rarely studied. Here, we show, for the first time, that conditional inactivation of the gene encoding β-catenin in the primitive laryngopharyngeal epithelium leads to failure in separation of the vocal folds, which approximates the gross phenotype of laryngeal webbing. These defects can be traced to a series of morphogenesis defects, including delayed fusion of the epithelial lamina and formation of the laryngeal cecum, failed separation of the larynx and esophagus with reduced and disorganized cartilages and muscles. Parallel to these morphogenesis defects, inactivation of β-catenin disrupts stratification of epithelial cells and establishment of p63+ basal progenitors. These findings provide the first line of evidence that links β-catenin function to the cell proliferation and progenitor establishment during larynx and vocal fold development.
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Affiliation(s)
- Vlasta Lungova
- Department of Surgery, University of Wisconsin-Madison, 5107 WIMR, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Jamie M Verheyden
- Laboratory of Genetics, Biotechnology Center, University of Wisconsin-Madison, 425G Henry Mall, Madison, WI 53706, USA
| | - Xin Sun
- Laboratory of Genetics, Biotechnology Center, University of Wisconsin-Madison, 425G Henry Mall, Madison, WI 53706, USA
| | - Susan L Thibeault
- Department of Surgery, University of Wisconsin-Madison, 5107 WIMR, 1111 Highland Avenue, Madison, WI 53705, USA
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10
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Verheyden JM, Sun X. Embryology meets molecular biology: Deciphering the apical ectodermal ridge. Dev Biol 2017; 429:387-390. [PMID: 28131856 DOI: 10.1016/j.ydbio.2017.01.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/04/2017] [Accepted: 01/24/2017] [Indexed: 01/28/2023]
Abstract
More than sixty years ago, while studying feather tracks on the shoulder of the chick embryo, Dr. John Saunders used Nile Blue dye to stain the tissue. There, he noticed a darkly stained line of cells that neatly rims the tip of the growing limb bud. Rather than ignoring this observation, he followed it up by removing this tissue and found that it led to a striking truncation of the limb skeletons. This landmark experiment marks the serendipitous discovery of the apical ectodermal ridge (AER), the quintessential embryonic structure that drives the outgrowth of the limb. Dr. Saunders continued to lead the limb field for the next fifty years, not just through his own work, but also by inspiring the next generation of researchers through his infectious love of science. Together, he and those who followed ushered in the discovery of fibroblast growth factor (FGF) as the AER molecule. The seamless marriage of embryology and molecular biology that led to the decoding of the AER serves as a shining example of how discoveries are made for the rest of the developmental biology field.
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Affiliation(s)
- Jamie M Verheyden
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, United States
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, United States.
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11
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Hines EA, Verheyden JM, Lashua AJ, Larson SC, Branchfield K, Domyan ET, Gao J, Harvey JF, Herriges JC, Hu L, Mcculley DJ, Throckmorton K, Yokoyama S, Ikeda A, Xu G, Sun X. Syndactyly in a novel Fras1(rdf) mutant results from interruption of signals for interdigital apoptosis. Dev Dyn 2016; 245:497-507. [PMID: 26813283 DOI: 10.1002/dvdy.24389] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 01/05/2016] [Accepted: 01/17/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Fras1 encodes an extracellular matrix protein that is critical for the establishment of the epidermal basement membrane during gestation. In humans, mutations in FRAS1 cause Fraser Syndrome (FS), a pleiotropic condition with many clinical presentations such as limb, eye, kidney, and craniofacial deformations. Many of these defects are mimicked by loss of Fras1 in mice, and are preceded by the formation of epidermal blisters in utero. RESULTS In this study, we identified a novel ENU-derived rounded foot (rdf) mouse mutant with highly penetrant hindlimb soft-tissue syndactyly, among other structural defects. Mapping and sequencing revealed that rdf is a novel loss-of-function nonsense allele of Fras1 (Fras1(rdf)). Focusing on the limb, we found that the Fras1(rdf) syndactyly phenotype originates from loss of interdigital cell death (ICD). Despite normal expression of bone morphogenetic protein (BMP) ligands and their receptors, the BMP downstream target gene Msx2, which is also necessary and sufficient to promote ICD, was down-regulated in the interdigital regions of Fras1(rdf) hindlimb buds. CONCLUSIONS The close correlation between limb bud epidermal blistering, decreased Msx2 expression, and reduced ICD in the Fras1(rdf) hindlimb buds suggests that epithelium detachment from the mesenchyme may create a physical gap that interrupts the transmission of BMP, among other signals, resulting in soft tissue syndactyly.
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Affiliation(s)
| | | | - Amber J Lashua
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | - Sarah C Larson
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | | | - Eric T Domyan
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | - Juan Gao
- Institute of Biochemistry and Cell Biology Shanghai Institute for Biological Sciences Chinese Academy of Sciences Shanghai, China, 200031
| | - Julie F Harvey
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | - John C Herriges
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | - Linghan Hu
- Zhiyuan College Shanghai Jiao Tong University Shanghai, China, 200240
| | - David J Mcculley
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | | | | | - Akihiro Ikeda
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
| | - Guoliang Xu
- Institute of Biochemistry and Cell Biology Shanghai Institute for Biological Sciences Chinese Academy of Sciences Shanghai, China, 200031
| | - Xin Sun
- Laboratory of Genetics University of Wisconsin Madison, WI, 53706
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12
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Herriges JC, Verheyden JM, Zhang Z, Sui P, Zhang Y, Anderson MJ, Swing DA, Zhang Y, Lewandoski M, Sun X. FGF-Regulated ETV Transcription Factors Control FGF-SHH Feedback Loop in Lung Branching. Dev Cell 2016; 35:322-32. [PMID: 26555052 DOI: 10.1016/j.devcel.2015.10.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 09/17/2015] [Accepted: 10/09/2015] [Indexed: 01/13/2023]
Abstract
The mammalian lung forms its elaborate tree-like structure following a largely stereotypical branching sequence. While a number of genes have been identified to play essential roles in lung branching, what coordinates the choice between branch growth and new branch formation has not been elucidated. Here we show that loss of FGF-activated transcription factor genes, Etv4 and Etv5 (collectively Etv), led to prolonged branch tip growth and delayed new branch formation. Unexpectedly, this phenotype is more similar to mutants with increased rather than decreased FGF activity. Indeed, an increased Fgf10 expression is observed, and reducing Fgf10 dosage can attenuate the Etv mutant phenotype. Further evidence indicates that ETV inhibits Fgf10 via directly promoting Shh expression. SHH in turn inhibits local Fgf10 expression and redirects growth, thereby initiating new branches. Together, our findings establish ETV as a key node in the FGF-ETV-SHH inhibitory feedback loop that dictates branching periodicity.
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Affiliation(s)
- John C Herriges
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jamie M Verheyden
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Zhen Zhang
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Physiological Chemistry, Genentech, Inc., South San Francisco, CA 94080, USA
| | - Pengfei Sui
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ying Zhang
- Cancer and Developmental Biology Lab, National Cancer Institute, Frederick, MD 21702, USA
| | - Matthew J Anderson
- Cancer and Developmental Biology Lab, National Cancer Institute, Frederick, MD 21702, USA
| | - Deborah A Swing
- Mouse Cancer Genetics Program, National Cancer Institute, Frederick, MD 21702, USA
| | - Yan Zhang
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Mark Lewandoski
- Cancer and Developmental Biology Lab, National Cancer Institute, Frederick, MD 21702, USA
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.
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13
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Branchfield K, Nantie L, Verheyden JM, Sui P, Wienhold MD, Sun X. Pulmonary neuroendocrine cells function as airway sensors to control lung immune response. Science 2016; 351:707-10. [PMID: 26743624 PMCID: PMC4860346 DOI: 10.1126/science.aad7969] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/16/2015] [Indexed: 12/16/2022]
Abstract
The lung is constantly exposed to environmental atmospheric cues. How it senses and responds to these cues is poorly defined. Here, we show that Roundabout receptor (Robo) genes are expressed in pulmonary neuroendocrine cells (PNECs), a rare, innervated epithelial population. Robo inactivation in mouse lung results in an inability of PNECs to cluster into sensory organoids and triggers increased neuropeptide production upon exposure to air. Excess neuropeptides lead to an increase in immune infiltrates, which in turn remodel the matrix and irreversibly simplify the alveoli. We demonstrate in vivo that PNECs act as precise airway sensors that elicit immune responses via neuropeptides. These findings suggest that the PNEC and neuropeptide abnormalities documented in a wide array of pulmonary diseases may profoundly affect symptoms and progression.
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Affiliation(s)
- Kelsey Branchfield
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Leah Nantie
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jamie M Verheyden
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Pengfei Sui
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Mark D Wienhold
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Xin Sun
- Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.
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14
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Noble DC, Aoki ST, Ortiz MA, Kim KW, Verheyden JM, Kimble J. Genomic Analyses of Sperm Fate Regulator Targets Reveal a Common Set of Oogenic mRNAs in Caenorhabditis elegans. Genetics 2016; 202:221-34. [PMID: 26564160 PMCID: PMC4701086 DOI: 10.1534/genetics.115.182592] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/03/2015] [Indexed: 12/18/2022] Open
Abstract
Germ cell specification as sperm or oocyte is an ancient cell fate decision, but its molecular regulation is poorly understood. In Caenorhabditis elegans, the FOG-1 and FOG-3 proteins behave genetically as terminal regulators of sperm fate specification. Both are homologous to well-established RNA regulators, suggesting that FOG-1 and FOG-3 specify the sperm fate post-transcriptionally. We predicted that FOG-1 and FOG-3, as terminal regulators of the sperm fate, might regulate a battery of gamete-specific differentiation genes. Here we test that prediction by exploring on a genomic scale the messenger RNAs (mRNAs) associated with FOG-1 and FOG-3. Immunoprecipitation of the proteins and their associated mRNAs from spermatogenic germlines identifies 81 FOG-1 and 722 FOG-3 putative targets. Importantly, almost all FOG-1 targets are also FOG-3 targets, and these common targets are strongly biased for oogenic mRNAs. The discovery of common target mRNAs suggested that FOG-1 and FOG-3 work together. Consistent with that idea, we find that FOG-1 and FOG-3 proteins co-immunoprecipitate from both intact nematodes and mammalian tissue culture cells and that they colocalize in germ cells. Taking our results together, we propose a model in which FOG-1 and FOG-3 work in a complex to repress oogenic transcripts and thereby promote the sperm fate.
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Affiliation(s)
- Daniel C Noble
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Scott T Aoki
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Marco A Ortiz
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Kyung Won Kim
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Jamie M Verheyden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Judith Kimble
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706 Howard Hughes Medical Institute, University of Wisconsin, Madison, Wisconsin 53706
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15
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Branchfield K, Li R, Lungova V, Verheyden JM, McCulley D, Sun X. A three-dimensional study of alveologenesis in mouse lung. Dev Biol 2015; 409:429-41. [PMID: 26632490 DOI: 10.1016/j.ydbio.2015.11.017] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 11/23/2015] [Accepted: 11/23/2015] [Indexed: 01/08/2023]
Abstract
Alveologenesis is the final step of lung maturation, which subdivides the alveolar region of the lung into smaller units called alveoli. Each of the nascent dividers serves as a new gas-exchange surface, and collectively they drastically increase the surface area for breathing. Disruption of alveologenesis results in simplification of alveoli, as is seen in premature infants diagnosed with bronchopulmonary dysplasia (BPD), a prevalent lung disease that is often associated with lifelong breathing deficiencies. To date, a majority of studies of alveologenesis rely on two-dimensional (2D) analysis of tissue sections. Given that an overarching theme of alveologenesis is thinning and extension of the epithelium and mesenchyme to facilitate gas exchange, often only a small portion of a cell or a cellular structure is represented in a single 2D plane. Here, we use a three-dimensional (3D) approach to examine the structural architecture and cellular composition of myofibroblasts, alveolar type 2 cells, elastin and lipid droplets in normal as well as BPD-like mouse lung. We found that 2D finger-like septal crests, commonly used to depict growing alveolar septae, are often artifacts of sectioning through fully established alveolar walls. Instead, a more accurate representation of growing septae are 3D ridges that are lined by platelet-derived growth factor receptor alpha (PDGFRA) and alpha smooth muscle actin (α-SMA)-expressing myofibroblasts, as well as the elastin fibers that they produce. Accordingly in 3D, both α-SMA and elastin were each found in connected networks underlying the 3D septal ridges rather than as isolated dots at the tip of 2D septal crests. Analysis through representative stages of alveologenesis revealed unappreciated dynamic changes in these patterns. PDGFRA-expressing cells are only α-SMA-positive during the first phase of alveologenesis, but not in the second phase, suggesting that the two phases of septae formation may be driven by distinct mechanisms. Thin elastin fibers are already present in the alveolar region prior to alveologenesis, suggesting that during alveologenesis, there is not only new elastin deposition, but also extensive remodeling to transform thin and uniformly distributed fibers into thick cables that rim the nascent septae. Analysis of several genetic as well as hyperoxia-induced models of BPD revealed that the myofibroblast organization is perturbed in all, regardless of whether the origin of defect is epithelial, mesenchymal, endothelial or environmental. Finally, analysis of relative position of PDGFRA-positive cells and alveolar type 2 cells reveal that during alveologenesis, these two cell types are not always adjacent to one another. This result suggests that the niche and progenitor relationship afforded by their close juxtaposition in the adult lung may be a later acquired property. These insights revealed by 3D reconstruction of the septae set the foundation for future investigations of the mechanisms driving normal alveologenesis, as well as causes of alveolar simplification in BPD.
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Affiliation(s)
- Kelsey Branchfield
- Laboratory of Genetics, University of Wisconsin-Madison Madison, WI 52706, United States
| | - Rongbo Li
- Laboratory of Genetics, University of Wisconsin-Madison Madison, WI 52706, United States
| | - Vlasta Lungova
- Department of Surgery, University of Wisconsin-Madison Madison, WI 53706, United States
| | - Jamie M Verheyden
- Laboratory of Genetics, University of Wisconsin-Madison Madison, WI 52706, United States
| | - David McCulley
- Department of Pediatrics University of Wisconsin-Madison Madison, WI 53706, United States
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin-Madison Madison, WI 52706, United States.
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16
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Lungova V, Verheyden JM, Herriges J, Sun X, Thibeault SL. Ontogeny of the mouse vocal fold epithelium. Dev Biol 2015; 399:263-82. [PMID: 25601450 PMCID: PMC4352410 DOI: 10.1016/j.ydbio.2014.12.037] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 11/09/2014] [Accepted: 12/23/2014] [Indexed: 01/12/2023]
Abstract
This investigation provides the first systematic determination of the cellular and molecular progression of vocal fold (VF) epithelium development in a murine model. We define five principal developmental events that constitute the progression from VF initiation in the embryonic anterior foregut tube to fully differentiated and functional adult tissue. These developmental events include (1) the initiation of the larynx and vocal folds with apposition of the lateral walls of the primitive laryngopharynx (embryonic (E) day 10.5); (2) the establishment of the epithelial lamina with fusion of the lateral walls of the primitive laryngopharynx (E11.5); (3) the epithelial lamina recanalization and separation of VFs (E13.5-18.5); (4) the stratification of the vocal folds (E13.5-18.5); and (5) the maturation of vocal fold epithelium (postnatal stages). The illustration of these morphogenetic events is substantiated by dynamic changes in cell proliferation and apoptosis, as well as the expression pattern of key transcription factors, FOXA2, SOX2 and NKX2-1 that specify and pattern the foregut endoderm. Furthermore, we documented the gradual conversion of VF epithelial cells from simple precursors expressing cytokeratins 8 and 18 in the embryo into mature stratified epithelial cells also expressing cytokeratins 5 and 14 in the adult. Interestingly, in the adult, cytokeratins 5 and 14 appear to be expressed in all cell layers in the VF, in contrast to their preferential localization to the basal cell layer in surrounding epithelium. To begin investigating the role of signaling molecules in vocal fold development, we characterized the expression pattern of SHH pathway genes, and how loss of Shh affects vocal fold development in the mutant. This study defines the cellular and molecular context and serves as the necessary foundation for future functional investigations of VF formation.
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Affiliation(s)
- Vlasta Lungova
- Department of Surgery, UW Madison, 5107 WIMR, 1111 Highland Ave, Madison, WI 53705, USA
| | - Jamie M Verheyden
- Laboratory of Genetics, Biotechnology Center, UW Madison, 425-g Henry Mall, Madison, WI 53706, USA
| | - John Herriges
- Laboratory of Genetics, Biotechnology Center, UW Madison, 425-g Henry Mall, Madison, WI 53706, USA
| | - Xin Sun
- Laboratory of Genetics, Biotechnology Center, UW Madison, 425-g Henry Mall, Madison, WI 53706, USA.
| | - Susan L Thibeault
- Department of Surgery, UW Madison, 5107 WIMR, 1111 Highland Ave, Madison, WI 53705, USA.
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17
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Hines EA, Szakaly RJ, Leng N, Webster AT, Verheyden JM, Lashua AJ, Kendziorski C, Rosenthal LA, Gern JE, Sorkness RL, Sun X, Lemanske RF. Comparison of temporal transcriptomic profiles from immature lungs of two rat strains reveals a viral response signature associated with chronic lung dysfunction. PLoS One 2014; 9:e112997. [PMID: 25437859 PMCID: PMC4249857 DOI: 10.1371/journal.pone.0112997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Accepted: 10/17/2014] [Indexed: 11/25/2022] Open
Abstract
Early life respiratory viral infections and atopic characteristics are significant risk factors for the development of childhood asthma. It is hypothesized that repeated respiratory viral infections might induce structural remodeling by interfering with the normal process of lung maturation; however, the specific molecular processes that underlie these pathological changes are not understood. To investigate the molecular basis for these changes, we used an established Sendai virus infection model in weanling rats to compare the post-infection transcriptomes of an atopic asthma susceptible strain, Brown Norway, and a non-atopic asthma resistant strain, Fischer 344. Specific to this weanling infection model and not described in adult infection models, Sendai virus in the susceptible, but not the resistant strain, results in morphological abnormalities in distal airways that persist into adulthood. Gene expression data from infected and control lungs across five time points indicated that specific features of the immune response following viral infection were heightened and prolonged in lungs from Brown Norway rats compared with Fischer 344 rats. These features included an increase in macrophage cell number and related gene expression, which then transitioned to an increase in mast cell number and related gene expression. In contrast, infected Fischer F344 lungs exhibited more efficient restoration of the airway epithelial morphology, with transient appearance of basal cell pods near distal airways. Together, these findings indicate that the pronounced macrophage and mast cell responses and abnormal re-epithelialization precede the structural defects that developed and persisted in Brown Norway, but not Fischer 344 lungs.
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Affiliation(s)
- Elizabeth A. Hines
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Renee J. Szakaly
- School of Pharmacy, University of Wisconsin, Madison, Wisconsin, United States of America
- Department of Medicine, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Ning Leng
- Department of Statistics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Anais T. Webster
- School of Pharmacy, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Jamie M. Verheyden
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Amber J. Lashua
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Christina Kendziorski
- Department of Statistics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Louis A. Rosenthal
- Department of Medicine, University of Wisconsin, Madison, Wisconsin, United States of America
| | - James E. Gern
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Ronald L. Sorkness
- School of Pharmacy, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail: (XS); (RFL)
| | - Robert F. Lemanske
- Department of Medicine, University of Wisconsin, Madison, Wisconsin, United States of America
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail: (XS); (RFL)
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18
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Verheyden JM, Byrd DT, Kimble J. Chemical control of protein stability in C. elegans. Dev Biol 2011. [DOI: 10.1016/j.ydbio.2011.05.244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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19
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Jeong J, Verheyden JM, Kimble J. Cyclin E and Cdk2 control GLD-1, the mitosis/meiosis decision, and germline stem cells in Caenorhabditis elegans. PLoS Genet 2011; 7:e1001348. [PMID: 21455289 PMCID: PMC3063749 DOI: 10.1371/journal.pgen.1001348] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 02/18/2011] [Indexed: 11/29/2022] Open
Abstract
Coordination of the cell cycle with developmental events is crucial for generation of tissues during development and their maintenance in adults. Defects in that coordination can shift the balance of cell fates with devastating clinical effects. Yet our understanding of the molecular mechanisms integrating core cell cycle regulators with developmental regulators remains in its infancy. This work focuses on the interplay between cell cycle and developmental regulators in the Caenorhabditis elegans germline. Key developmental regulators control germline stem cells (GSCs) to self-renew or begin differentiation: FBF RNA–binding proteins promote self-renewal, while GLD RNA regulatory proteins promote meiotic entry. We first discovered that many but not all germ cells switch from the mitotic into the meiotic cell cycle after RNAi depletion of CYE-1 (C. elegans cyclin E) or CDK-2 (C. elegans Cdk2) in wild-type adults. Therefore, CYE-1/CDK-2 influences the mitosis/meiosis balance. We next found that GLD-1 is expressed ectopically in GSCs after CYE-1 or CDK-2 depletion and that GLD-1 removal can rescue cye-1/cdk-2 defects. Therefore, GLD-1 is crucial for the CYE-1/CDK-2 mitosis/meiosis control. Indeed, GLD-1 appears to be a direct substrate of CYE-1/CDK-2: GLD-1 is a phosphoprotein; CYE-1/CDK-2 regulates its phosphorylation in vivo; and human cyclin E/Cdk2 phosphorylates GLD-1 in vitro. Transgenic GLD-1(AAA) harbors alanine substitutions at three consensus CDK phosphorylation sites. GLD-1(AAA) is expressed ectopically in GSCs, and GLD-1(AAA) transgenic germlines have a smaller than normal mitotic zone. Together these findings forge a regulatory link between CYE-1/CDK-2 and GLD-1. Finally, we find that CYE-1/CDK-2 works with FBF-1 to maintain GSCs and prevent their meiotic entry, at least in part, by lowering GLD-1 abundance. Therefore, CYE-1/CDK-2 emerges as a critical regulator of stem cell maintenance. We suggest that cyclin E and Cdk-2 may be used broadly to control developmental regulators. How are cell cycle regulators coordinated with cell fate and patterning regulators during development? Several studies suggest that core cell cycle regulators can influence development, but molecular mechanisms remain unknown for the most part. We have tackled this question in the nematode Caenorhabditis elegans. Specifically, we have investigated how cell cycle regulators affect germline stem cells. Previous work had identified conserved developmental regulators that control the choice between self-renewal and differentiation in this tissue. In this work, we focus on cyclin E/Cdk-2, which is a core cell cycle kinase, and GLD-1, a key regulator of stem cell differentiation. Our work shows that cyclin E/Cdk-2 phosphorylates GLD-1 and lowers its abundance in stem cells via a post-translational mechanism. We also find that a post-transcriptional GLD-1 regulator, called FBF-1, works synergistically with cyclin E/Cdk-2 to ensure that GLD-1 is off in germline stem cells. When both FBF-1 and cyclin E/Cdk-2 are removed, the stem cells are no longer maintained and instead differentiate. Our findings reveal that cyclin E/Cdk-2 kinase is a critical stem cell regulator and provide a paradigm for how cell cycle regulators interface with developmental regulators.
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Affiliation(s)
- Johan Jeong
- Program in Cellular and Molecular Biology, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
| | - Jamie M. Verheyden
- Howard Hughes Medical Institute, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
| | - Judith Kimble
- Program in Cellular and Molecular Biology, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
- Howard Hughes Medical Institute, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
- * E-mail:
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20
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Zhang Z, Verheyden JM, Hassell JA, Sun X. FGF-regulated Etv genes are essential for repressing Shh expression in mouse limb buds. Dev Cell 2009; 16:607-13. [PMID: 19386269 DOI: 10.1016/j.devcel.2009.02.008] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 01/30/2009] [Accepted: 02/06/2009] [Indexed: 12/21/2022]
Abstract
Anterior-posterior (A-P) patterning of the vertebrate limb is controlled by sonic hedgehog (SHH) signaling, and the precise restriction of Shh expression to the posterior limb bud is essential for its polarizing effect. Fibroblast growth factor (FGF) signaling, a key control of proximal-distal (P-D) limb outgrowth, is known to promote Shh expression in the posterior limb bud. Here, we show that conditional knockout of the FGF-activated transcription factor genes Etv4 and Etv5 in mouse led to ectopic Shh expression in the anterior limb bud and a preaxial polydactyly (PPD) skeletal phenotype. These unexpected results suggest that ETV4 and ETV5 act downstream of FGF signaling to inhibit Shh expression in the anterior limb bud. This finding elucidates a novel aspect of the mechanism coordinating limb development along the A-P and P-D axes.
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Affiliation(s)
- Zhen Zhang
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
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21
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Sun X, Verheyden JM. An Fgf/Gremlin Inhibitory Feedback Loop Triggers Termination of Limb Bud Outgrowth. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.176.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xin Sun
- GeneticsUniversity of Wisconsin‐MadisonMadisonWI
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22
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Verheyden JM, Sun X. Genetic Interactions Between FGF and SHH Signaling in the Vertebrate Limb. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a199-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jamie M Verheyden
- Laboratory of Genetics, University of Wisconsin‐Madison425 Henry MallMadisonWI53706
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin‐Madison425 Henry MallMadisonWI53706
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23
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Verheyden JM, Lewandoski M, Deng C, Harfe BD, Sun X. Conditional inactivation of Fgfr1 in mouse defines its role in limb bud establishment, outgrowth and digit patterning. Development 2005; 132:4235-45. [PMID: 16120640 PMCID: PMC6986394 DOI: 10.1242/dev.02001] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies have implicated fibroblast growth factor receptor 1 (FGFR1) in limb development. However, the precise nature and complexity of its role have not been defined. Here, we dissect Fgfr1 function in mouse limb by conditional inactivation of Fgfr1 using two different Cre recombinase-expressing lines. Use of the T (brachyury)-cre line led to Fgfr1 inactivation in all limb bud mesenchyme (LBM) cells during limb initiation. This mutant reveals FGFR1 function in two phases of limb development. In a nascent limb bud, FGFR1 promotes the length of the proximodistal (PD) axis while restricting the dimensions of the other two axes. It also serves an unexpected role in limiting LBM cell number in this early phase. Later on during limb outgrowth, FGFR1 is essential for the expansion of skeletal precursor population by maintaining cell survival. Use of mice carrying the sonic hedgehog(cre) (Shh(cre)) allele led to Fgfr1 inactivation in posterior LBM cells. This mutant allows us to test the role of Fgfr1 in gene expression regulation without disturbing limb bud growth. Our data show that during autopod patterning, FGFR1 influences digit number and identity, probably through cell-autonomous regulation of Shh expression. Our study of these two Fgfr1 conditional mutants has elucidated the multiple roles of FGFR1 in limb bud establishment, growth and patterning.
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Affiliation(s)
- Jamie M. Verheyden
- Laboratory of Genetics, University of Wisconsin-Madison, 425G Henry Mall, Madison, WI 53706, USA
| | - Mark Lewandoski
- Cancer and Developmental Biology Laboratory, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, MD 21702, USA
| | - Chuxia Deng
- Genetics of Development and Disease Branch, NIDDK, NIH, 10/9N105, 10 Center Drive, Bethesda, MD 20892, USA
| | - Brian D. Harfe
- University of Florida College of Medicine, Department of Molecular Genetics and Microbiology, Gainesville, FL 32610-0266, USA
| | - Xin Sun
- Laboratory of Genetics, University of Wisconsin-Madison, 425G Henry Mall, Madison, WI 53706, USA
- Author for correspondence: ()
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