- Pediatric Pulmonary
Residency: UCSF Pediatric Residency (2007) CA
Medical Education: St Louis University School of Medicine (2004) MO
Board Certification: American Board of Pediatrics, Pediatric Pulmonary (2010)
Board Certification: American Board of Pediatrics, Pediatrics (2007)
Fellowship: Lucile Packard Children's Hospital (2011) CA
Independent Studies (3)
- Out-of-Department Advanced Research Laboratory in Experimental Biology
BIO 199X (Aut)
- Undergraduate Directed Reading/Research
PEDS 199 (Spr, Sum)
- Undergraduate Research
MED 199 (Aut, Win, Spr, Sum)
- Out-of-Department Advanced Research Laboratory in Experimental Biology
Axon-like protrusions promote small cell lung cancer migration and metastasis.
Metastasis is the main cause of death in cancer patients but remains a poorly understood process. Small cell lung cancer (SCLC) is one of the most lethal and most metastatic cancer types. SCLC cells normally express neuroendocrine and neuronal gene programs but accumulating evidence indicates that these cancer cells become relatively more neuronal and less neuroendocrine as they gain the ability to metastasize. Here we show that mouse and human SCLC cells in culture and in vivo can grow cellular protrusions that resemble axons. The formation of these protrusions is controlled by multiple neuronal factors implicated in axonogenesis, axon guidance, and neuroblast migration. Disruption of these axon-like protrusions impairs cell migration in culture and inhibits metastatic ability in vivo. The co-option of developmental neuronal programs is a novel molecular and cellular mechanism that contributes to the high metastatic ability of SCLC.
View details for DOI 10.7554/eLife.50616
View details for PubMedID 31833833
Rare Pulmonary Neuroendocrine Cells Are Stem Cells Regulated by Rb, p53, and Notch.
2019; 179 (2): 403–16.e23
Pulmonary neuroendocrine (NE) cells are neurosensory cells sparsely distributed throughout the bronchial epithelium, many in innervated clusters of 20-30 cells. Following lung injury, NE cells proliferate and generate other cell types to promote epithelial repair. Here, we show that only rare NE cells, typically 2-4 per cluster, function as stem cells. These fully differentiated cells display features of classical stem cells. Most proliferate (self-renew) following injury, and some migrate into the injured area. A week later, individual cells, often just one per cluster, lose NE identity (deprogram), transit amplify, and reprogram to other fates, creating large clonal repair patches. Small cell lung cancer (SCLC) tumor suppressors regulate the stem cells: Rb and p53 suppress self-renewal, whereas Notch marks the stem cells and initiates deprogramming and transit amplification. We propose that NE stem cells give rise to SCLC, and transformation results from constitutive activation of stem cell renewal and inhibition of deprogramming.
View details for DOI 10.1016/j.cell.2019.09.010
View details for PubMedID 31585080
- A national registry for childhood interstitial and diffuse lung diseases in the United States. EUROPEAN RESPIRATORY SOC JOURNALS LTD. 2018
Single-cell transcriptomics of 20 mouse organs creates a Tabula Muris.
2018; 562 (7727): 367–72
Here we present a compendium of single-cell transcriptomic data from the model organism Mus musculus that comprises more than 100,000 cells from 20 organs and tissues. These data represent a new resource for cell biology, reveal gene expression in poorly characterized cell populations and enable the direct and controlled comparison of gene expression in cell types that are shared between tissues, such as T lymphocytes and endothelial cells from different anatomical locations. Two distinct technical approaches were used for most organs: one approach, microfluidic droplet-based 3'-end counting, enabled the survey of thousands of cells at relatively low coverage, whereas the other, full-length transcript analysis based on fluorescence-activated cell sorting, enabled the characterization of cell types with high sensitivity and coverage. The cumulative data provide the foundation for an atlas of transcriptomic cell biology.
View details for DOI 10.1038/s41586-018-0590-4
View details for PubMedID 30283141
- Pulmonary arteriovenous malformations: an uncharacterised phenotype of dyskeratosis congenita and related telomere biology disorders EUROPEAN RESPIRATORY JOURNAL 2017; 49 (1)
Respiratory System Involvement in Costello Syndrome
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
2016; 170 (7): 1849-1857
Costello syndrome (CS) is a multisystem disorder caused by heterozygous germline mutations in the HRAS proto-oncogene. Respiratory system complications have been reported in individuals with CS, but a comprehensive description of the full spectrum and incidence of respiratory symptoms in these patients is not available. Here, we report the clinical course of four CS patients with respiratory complications as a major cause of morbidity. Review of the literature identified 56 CS patients with descriptions of their neonatal course and 17 patients in childhood/adulthood. We found that in the neonatal period, respiratory complications are seen in approximately 78% of patients with transient respiratory distress reported in 45% of neonates. Other more specific respiratory diagnoses were reported in 62% of patients, the majority of which comprised disorders of the upper and lower respiratory tract. Symptoms of upper airway obstruction were reported in CS neonates but were more commonly diagnosed in childhood/adulthood (71%). Analysis of HRAS mutations and their respiratory phenotype revealed that the common p.Gly12Ser mutation is more often associated with transient respiratory distress and other respiratory diagnoses. Respiratory failure and dependence on mechanical ventilation occurs almost exclusively with rare mutations. In cases of prenatally diagnosed CS, the high incidence of respiratory complications in the neonatal period should prompt anticipatory guidance and development of a postnatal management plan. This may be important in cases involving rarer mutations. Furthermore, the high frequency of airway obstruction in CS patients suggests that otorhinolaryngological evaluation and sleep studies should be considered. © 2016 Wiley Periodicals, Inc.
View details for DOI 10.1002/ajmg.a.37655
View details for PubMedID 27102959
Formation of a Neurosensory Organ by Epithelial Cell Slithering
2015; 163 (2): 394-405
Epithelial cells are normally stably anchored, maintaining their relative positions and association with the basement membrane. Developmental rearrangements occur through cell intercalation, and cells can delaminate during epithelial-mesenchymal transitions and metastasis. We mapped the formation of lung neuroepithelial bodies (NEBs), innervated clusters of neuroendocrine/neurosensory cells within the bronchial epithelium, revealing a targeted mode of cell migration that we named "slithering," in which cells transiently lose epithelial character but remain associated with the membrane while traversing neighboring epithelial cells to reach cluster sites. Immunostaining, lineage tracing, clonal analysis, and live imaging showed that NEB progenitors, initially distributed randomly, downregulate adhesion and polarity proteins, crawling over and between neighboring cells to converge at diametrically opposed positions at bronchial branchpoints, where they reestablish epithelial structure and express neuroendocrine genes. There is little accompanying progenitor proliferation or apoptosis. Activation of the slithering program may explain why lung cancers arising from neuroendocrine cells are highly metastatic.
View details for DOI 10.1016/j.cell.2015.09.021
View details for Web of Science ID 000362952700016
View details for PubMedID 26435104
View details for PubMedCentralID PMC4597318
Cellular mechanisms of alveolar pathology in childhood interstitial lung diseases: current insights from mouse genetics
CURRENT OPINION IN PEDIATRICS
2015; 27 (3): 341-347
Childhood interstitial lung diseases (ILDs) are a diverse class of disorders affecting the alveolar gas exchange region that lack specific treatments and are usually fatal. Here, we integrate recent insights into alveolar cell biology with histopathology from well characterized mutations of surfactant-associated genes. We take a reductionist approach by parsing discrete histological features and correlating each to perturbation of a particular function of the alveolar epithelial type II (AT2) cell, the central driver of disease, to generate a working model for the cellular mechanisms of disease pathogenesis.The application of genetically modified mice and single cell genomics has yielded new insights into lung biology, including the identification of a bipotent alveolar progenitor in development, mapping of adult AT2 stem cells in vivo, and demonstration that latent cooperative interactions with fibroblasts can be pathologically activated by targeted injury of the AT2 cell.As we learn more about individual and cooperative roles for alveolar cells in health, we can dissect how perturbations of specific cellular functions contribute to disease in childhood ILDs. We hope our updated model centered around the AT2 cell as the initiator of disease provides a cellular framework that researchers can build upon and revise as they identify the specific molecular signals within and between alveolar cells that mediate the diverse pathologic features, so that targeted pharmacologic and cell-based treatments for patients can ultimately be engineered.
View details for DOI 10.1097/MOP.0000000000000227
View details for Web of Science ID 000354214800013
View details for PubMedID 25888154
View details for PubMedCentralID PMC4466102
Interstitial lung disease in children.
Current opinion in pediatrics
2014; 26 (3): 320-327
There has been tremendous progress in the approach to childhood interstitial lung diseases (chILD), with particular recognition that interstitial lung disease (ILD) in infants is often distinct from the forms that occur in older children and adults. Diagnosis is challenging because of the rarity of ILD and the fact that the presenting symptoms of ILD often overlap those of common respiratory disorders. This review summarizes the newly published recommendations for diagnosis and management, and highlights the recent scientific advances in several specific forms of chILD.Clinical practice guidelines emphasize the role for chest computed tomography, genetic testing, and lung biopsy in the diagnostic evaluation of children with suspected ILD. Recent studies have better defined the characteristics and molecular understanding of several different forms of ILD, including neuroendocrine cell hyperplasia of infancy and ILD, due to mutations in genes affecting surfactant production and metabolism. Despite significant progress, definitive therapies are often lacking.chILD encompasses a collection of rare, diffuse lung diseases. Timely recognition of children with suspected ILD and initiation of appropriate diagnostic evaluations will facilitate medical management. Systematic approaches to clinical care and further studies are needed to improve the outcomes of children with these rare disorders.
View details for DOI 10.1097/MOP.0000000000000094
View details for PubMedID 24752172
PML-dependent apoptosis after DNA damage is regulated by the checkpoint kinase hCds1/Chk2
NATURE CELL BIOLOGY
2002; 4 (11): 865-870
The promyelocytic leukaemia (PML) gene is translocated in most acute promyelocytic leukaemias and encodes a tumour suppressor protein. PML is involved in multiple apoptotic pathways and is thought to be pivotal in gamma irradiation-induced apoptosis. The DNA damage checkpoint kinase hCds1/Chk2 is necessary for p53-dependent apoptosis after gamma irradiation. In addition, gamma irradiation-induced apoptosis also occurs through p53-independent mechanisms, although the molecular mechanism remains largely unknown. Here, we report that hCds1/Chk2 mediates gamma irradiation-induced apoptosis in a p53-independent manner through an ataxia telangiectasia-mutated (ATM)-hCds1/Chk2-PML pathway. Our results provide the first evidence of a functional relationship between PML and a checkpoint kinase in gamma irradiation-induced apoptosis.
View details for DOI 10.1038/ncb869
View details for Web of Science ID 000179137700015
View details for PubMedID 12402044
Localization, dynamics, and protein interactions reveal distinct roles for ER and Golgi SNAREs
JOURNAL OF CELL BIOLOGY
1998; 141 (7): 1489-1502
ER-to-Golgi transport, and perhaps intraGolgi transport involves a set of interacting soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins including syntaxin 5, GOS-28, membrin, rsec22b, and rbet1. By immunoelectron microscopy we find that rsec22b and rbet1 are enriched in COPII-coated vesicles that bud from the ER and presumably fuse with nearby vesicular tubular clusters (VTCs). However, all of the SNAREs were found on both COPII- and COPI-coated membranes, indicating that similar SNARE machinery directs both vesicle pathways. rsec22b and rbet1 do not appear beyond the first Golgi cisterna, whereas syntaxin 5 and membrin penetrate deeply into the Golgi stacks. Temperature shifts reveal that membrin, rsec22b, rbet1, and syntaxin 5 are present together on membranes that rapidly recycle between peripheral and Golgi-centric locations. GOS-28, on the other hand, maintains a fixed localization in the Golgi. By immunoprecipitation analysis, syntaxin 5 exists in at least two major subcomplexes: one containing syntaxin 5 (34-kD isoform) and GOS-28, and another containing syntaxin 5 (41- and 34-kD isoforms), membrin, rsec22b, and rbet1. Both subcomplexes appear to involve direct interactions of each SNARE with syntaxin 5. Our results indicate a central role for complexes among rbet1, rsec22b, membrin, and syntaxin 5 (34 and 41 kD) at two membrane fusion interfaces: the fusion of ER-derived vesicles with VTCs, and the assembly of VTCs to form cis-Golgi elements. The 34-kD syntaxin 5 isoform, membrin, and GOS-28 may function in intraGolgi transport.
View details for Web of Science ID 000074605300002
View details for PubMedID 9647643
Protein interactions regulating vesicle transport between the endoplasmic reticulum and Golgi apparatus in mammalian cells
1997; 89 (1): 149-158
The proposed cis-Golgi vesicle receptor syntaxin 5 was found in a complex with Golgi-associated SNARE of 28 kDa (GOS-28), rbet1, rsly1, and two novel proteins characterized herein: rat sec22b and membrin, both cytoplasmically oriented integral membrane proteins. The complex appears to recapitulate vesicle docking interactions of proteins originating from distinct compartments, since syntaxin 5, rbet1, and GOS-28 localize to Golgi membranes, whereas mouse sec22b and membrin accumulate in the endoplasmic reticulum. Protein interactions in the complex are dramatically rearranged by N-ethylmaleimide-sensitive factor. The complex consists of two or more subcomplexes with some members (rat sec22b and syntaxin 5) in common and others (rbet1 and GOS-28) mutually exclusively associated. We propose that these protein interactions determine vesicle docking/fusion fidelity between the endoplasmic reticulum and Golgi.
View details for Web of Science ID A1997WR68500018
View details for PubMedID 9094723