The Effects of Omega-3 Fatty Acids & Cyclic Adenosine Monophosphate on Transcription of Genes Involved in Arginine Metabolism
Date of Award
Master of Science (MS)
Farzaneh Daghigh, PhD
Brian J Balin, PhD
Marcus Bell, PhD
Cigarette smoke (CS) contributes to airway remodeling (AR) in asthma partly by dysregulating expression of genes involved in arginine metabolism (AM). Cyclic adenosine monophosphate (cAMP) modulates expression of enzymes involved in AM, but whether cAMP can counteract the effects of CS on AR in asthma is uncertain. Additionally, omega-3 polyunsaturated fatty acids (ω-3 PUFAs) have broad anti-inflammatory effects, but their role in AM in the context of CS and AR is unclear. The goal of this study was to elucidate the effects of the ω-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the cAMP analogue 8-bromo-cAMP (8-Br-cAMP), and nicotine on transcription of genes involved in AM. Since cAMP and ω-3 PUFAs have therapeutic roles in asthma, it was hypothesized that 8-Br-cAMP and ω-3 PUFAs would downregulate transcription of genes involved in AM irrespective of nicotine. The effects of 8-Br-cAMP, EPA, DHA, and nicotine on transcription of arginase-2 (ARG2), ornithine decarboxylase (ODC), and ornithine aminotransferase (OAT) were tested in normal human lung fibroblasts (NHLF) and asthmatic diseased human lung fibroblasts (DHLF) using reverse transcriptase quantitative real time polymerase chain reaction (RT-qPCR). 8-Br-cAMP treatment for 24 hours downregulated ARG2 transcription in NHLF and DHLF while upregulating ODC and OAT transcription in DHLF alone. EPA and EPA+DHA downregulated transcription of ARG2 in NHLF and DHLF. EPA+DHA downregulated ODC transcription in NHLF alone. DHA did not affect transcription of any of the genes studied, while nicotine upregulated ARG2 inconsistently. The results demonstrate that cAMP and ω-3 PUFAs modulate transcription of genes involved in AM, whereas nicotine does not. The downregulatory effect of EPA and EPA+DHA on ARG2 transcription may play a role in the anti-AR effects of ω-3 PUPAs.
Duggirala, Vamsee K., "The Effects of Omega-3 Fatty Acids & Cyclic Adenosine Monophosphate on Transcription of Genes Involved in Arginine Metabolism" (2015). PCOM Biomedical Studies Student Scholarship. 101.