Vitiello Lab
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The Vitiello lab is interested in redox-sensitive pathways that regulate lung growth by transcribing changes in respiratory oxygen concentration into developmental signals that affect postnatal proliferation, differentiation, and viability of alveolar epithelial cells. Molecular Pathways Regulating Alveolar Growth during Development and Neonatal Injury
Prematurely born babies of very low birth weight suffer from respiratory problems because their lungs are underdeveloped. Without proper lung function, preemies have inadequate tissue oxygen levels and develop tissue hypoxia. Therapeutic intervention to improve pulmonary function is frequently required to maintain normal tissue oxygen levels. Preemies are administered excess oxygen (hyperoxia) in order to increase oxygen delivery into the lungs, bloodstream, and tissues. While hyperoxia has tremendous therapeutic impact in preventing newborn mortality, there are long term deficits in lung function in children treated with oxygen at birth. We are most interested in how growth and development of alveoli (functional respiratory units of the lung) are effected by atmospheric oxygen levels. Alveolar growth is inhibited by hyperoxia; therefore, children treated with oxygen at birth may have impaired lung function. Preemies exposed to excessive hyperoxia over a period of time that are at risk for reduced lung growth are clinically diagnosed with a newborn lung disease called bronchopulmonary dysplasia (BPD). In addition to reduced lung function, BPD patients also have higher rates of wheezing and respiratory illnesses, enhanced sensitivity to second hand cigarette smoke, and more out-of-school sick days. Some children diagnosed with BPD do not overcome these pathologies and deleterious respiratory effects can persist into adolescence and adulthood. Since hyperoxia at birth is associated with BPD, our lab studies how changes in the environmental oxygen concentration are translated into developmental signaling pathways required for proper lung growth in the newborn. Thiol oxidoreductases are unique enzymatic regulators of redox homeostasis since they may serve to directly transcribe changes in respiratory oxygen tension (such as during birth or newborn oxidative injury) into developmental pathways by modifying redox-sensitive signaling pathways. We primarily focus on thioredoxin and peroxiredoxin signaling in alveolar epithelium. To investigate thiol signaling during lung development and injury, we apply biochemical, molecular, and cellular approaches across tissue culture and rodent models. Our studies will provide insight into the molecular basis for BPD and may allow for development of novel therapeutic approaches. Project 1 – Redox Signaling via Thioredoxin-1 during Oxidative Injury Thioredoxin-1 (Trx1) is a redox-sensitive protein containing a dithiol-disulfide active site capable of reducing disulfide protein targets, thereby affecting their redox status and function. Therefore, Trx1 is a unique regulator of redox homeostasis since it can directly transcribe changes in oxygen tension (such as during birth or newborn oxidative injury) into developmental pathways by modifying redox-sensitive signaling pathways. Preliminary data shows that Trx1 accumulates in the nucleus during hyperoxia and that nuclear Trx1 is preferentially oxidized by hyperoxic treatment. Therefore, this project investigates the hypothesis that newborn oxygen alters nuclear redox status and alveolar development via Trx1. This project specifically investigates:
Project 2 – Maintenance of Mitochondrial Redox Status during Hyperoxic Stress Mitochondrial redox status is tightly regulated to resist oxidative changes associated with aerobic respiration. Perturbations in mitochondrial redox can activate Bcl-2 pro-apoptotic pathways and mitochondrial-dependent cell death. Therefore, this project investigates how thiol regulatory systems such as thioredoxin-2 (Trx2) and peroxiredoxin-3 (Prx3) prevent mitochondrial oxidation during hyperoxia. This project specifically investigates:
Project 3 – Identification of Txnip-Interacting Proteins in Alveolar Epithelium Thioredoxin-interacting protein (Txnip) is known to inhibit the redox activities of thioredoxins resulting in growth arrest and cell death. At birth, there is a dramatic reduction in Txnip expression which does not occur in animals born into hyperoxia, suggesting that Txnip expression is redox-sensitive and negatively correlates with pulmonary epithelial proliferation. While Txnip is thought to regulate vascular development through VEGF expression, the pathways regulating alveolar developmental processes are unknown. Therefore, goals of this project are to:
Project 4 – Determining Changes to the Thiol Proteome during Hyperoxia
Macromolecular damage requires accumulation of free radicals which are easily scavenged by anti-oxidant systems in low quantities. More sensitive changes in cellular redox status during oxidative stress are manifested through non-radical molecular modifications which can alter redox-sensitive signaling pathways. Cysteine and methionine are the only amino acids in proteins which contain molecular elements capable of undergoing reversible oxidation under biological conditions due to thiol modifications. Oxidation of adjacent thiol moieties results in disulfide formation which can change protein confirmation, enzyme activity, transporter activity, protein interactions, DNA interactions, trafficking, and degradation. This project identifies proteins with modified thiol status in response to hyperoxic injury through proteomic screening. Contact Information for Vitiello Lab: Associate Scientist |
