Nitric oxide (NO) transfer reactions between protein and peptide cysteines are thought to represent a regulated signaling process. In the pulmonary endothelium, endothelial nitric oxide synthase is required for the formation of S-nitrosothiols whereas, S-
Pulmonary hypertension (PH), high blood pressure in the lungs, is a disease with no known cure. Left untreated, this disease results in right heart failure and death. The studies performed during the past four years have focused on defining the role of S-
Pulmonary arterial hypertension (PAH), high blood pressure within the lung, is a progressive disease which is characterized by an increase in pulmonary arterial pressure and the formation of muscle around normally non- muscular small pulmonary arteries. Without treatment, PAH progresses rapidly to right heart failure and death. The mechanism(s) sensing the initiating event and transducing this signal into changes in protein expression to alter pulmonary physiology are unclear. The role S-nitrosothiols (SNO) play in the development of PAH is examined in this research project. In the pulmonary circulation, erythrocytes deliver SNOs to recipient target proteins on the surface of the endothelium as a function of oxygen saturation. In this context, erythrocytes can act as a molecular switch, monitoring changes in oxygen saturation to deliver SNOs to the vascular endothelium. We have developed a model in which Nacetyl cysteine (NAC) is used as a tracer to 1) monitor SNO formation, transfer and metabolism in vivo, 2) address the physiological and pathological consequences of SNO signaling in the pulmonary vasculature, and 3) identify SNO target proteins in this signaling pathway. Differences in SNO formation, transfer and metabolism and the role this pathway plays in gender specific differences associated with the development of PAH are examined. Studies for this grant period have focused on 1) defining the physiological pulmonary responses of S-nitrosothiols in female mice using our NAC model; 2) analyzing the physiological responses to S-nitrosothiols using mice deficient and null for proteins known to be involved in the formation and metabolism of Snitrosothiols and 3) identifying proteins and protein/protein interactions in the endothelium that are involved in this pathway. / NOTE: Annual rept. 15 Jan 2008-14 Jan 2009. / Supplementary Notes: The original document contains color images. / Availability Note: Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax
Nitric oxide (NO) transfer reactions between protein and peptide cystines are thought to represent a regulated signaling process. In the current studies, N-acetyl cysteine (NAC) was used as a bait reactant to measure NO transfer reactions in the blood and the vascular effects of these reactions in the pulmonary vasculature. In blood, NAC was converted to S-nitroso-N acetyl cysteine (SNOAC) both in vivo and ex vivo. Ex vivo, SNOAC formation was found to be dependent on oxyhemoglobin desaturation. The formation of SNOAC was found to be a relatively slow (K approximately 5.3 x 10-10M/s) pseudo-first order reaction. Physiologically, chronic administration of NAC resulted in the development of pulmonary hypertension that was indistinguishable from that caused by chronic hypoxia. Male endothelial nitric oxide synthase (eNOS) mice were protected from the effects of NAC but not SNOAC, demonstrating the importance of eNOS in this process. NAC was also found to increase the DNA binding activity of the transcription factor hypoxia inducible factor-1 (HIF-1). This appears to be due, in part, by altering the interaction between HIF-1 and protein von Hippel Lindau via S-nitrosylation of cysteine 162. Together the data suggest that erythrocytic oxygen desaturation signals hypoxia through NO transfer reactions in vivo. / NOTE: Annual rept. 15 Jan 2007-14 Jan 2008. / Supplementary Notes: The original document contains color images. / Availability Note: Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at firstname.lastname@example.org. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA.