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Bruce R. Pitt - Research
Molecular pharmacology of pulmonary circulation.
Nitric oxide in lung.
Metal ion homeostasis in vascular endothelium
Regulation of antioxidants in lung.
Gene therapy of acute and chronic lung disease.
My laboratory efforts are directed towards original studies on the molecular and cellular biology of lung. To date, this work has focused primarily on the role of oxidants and nitric oxide in affecting pulmonary endothelial and vascular smooth muscle cell function. Isolated primary cell cultures, genetically modified murine models and somatic gene transfer to lung have been used as model systems to identify the role of partially reduced oxygen and nitrogen species in the response of the lung to stress and injury.
Recent efforts have been directed towards understanding the role of S-nitrosylation of the metal binding intracellular protein, metallothoinein, on zinc homeostasis and endothelial cell function. These studies are aided by a number of microspectrofluorometric approaches including a green fluorescent protein modified chimera of metallothionein, suitable for fluorescence resonance energy transfer, as outlined in the schema below. This chimera contains an enhanced cyan fluorescent protein (ECYP) that serves as a donor for an enhanced yellow flourescence protein (EYFP) that are fused to the N- and C-termini respectively of human metallothionein Iia (hMTIIa). The result of these live cell fluorescence image studies has identified a unique role for metallothionein in NO mediated zinc release. NO mediated changes in labile zinc appear to be inhibitory in proapoptotic conditions in pulmonary endothelial cells contributing to the notion that S-nitrosylation of zinc sulfur clusters is an important component of NO signaling.
In collaboration with Song Li, M.D., in School of Pharmacy, non viral vectors capable of being targeted to pulmonary endothelium for somatic gene transfer of plasmid DNA or oligonucleotides are being developed. An example of transgene expression of the reporter molecule, beta galactosidase, in murine lung is shown in the figure below. Enhanced efficiency and greatly improved targeting to pulmonary endothelium has been accomplished by including an anti-PECAM antibody to the quaternary complex. This also results in minimizing toxicity and provides rational approach to pharmacogenetic therapy for pulmonary vascular disease such as pulmonary hypertension or acute lung injury.