Evaluation of nitric oxide synthesis in cell lines with respiratory chain defects

• Grant number: 06/00619-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2006
• End date: June 30, 2008
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Célia Harumi Tengan
• Grantee: Luana Tesser Gamba
• Host Institution: Departamento de Neurologia e Neurocirurgia. Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

It is believed that mitochondrial DNA (mtDNA) age-related deletions are caused by oxidative damage and that respiratory chain defects would lead to increased predisposition to these lesion due to increased free radical generation. Recent studies have shown mitochondrial production of nitric oxide (NO), a free radical that also participates in several physiological processes. In mitochondria NO inhibits cytochrome c oxidase (COX), complex IV of respiratory chain. Our preliminary results suggest alterations in NO synthesis in mitochondrial diseases depending on genotype. We observed decreased activity of nitric oxide synthase in muscle fibers with COX deficiency and increased production of nitrites, suggesting increased NO, in homoplasmic cybrids cell lines with mtDNA mutation. The objective of this study is to evaluate the production of NO using a fluorescent indicator in cell lines with different defects in respiratory chain. We will study cybrids cell lines with homoplasmy for mtDNA mutations and fibroblasts from patients. Our results will be correlated with previous results on the same cell lines but using a different approach for NO detection (Griess method) and with the expression of specific mitochondrial proteins for each respiratory chain.