Signal Transduction and Gene Regulation During Hypoxia Stress: A potential Role in Neurodegenerative Disease

摘要

Soldiers deployed to high altitude terrain or exposed to chemical toxins that induce ischemia or impaired oxidative metabolism in the central nervous system (CNS) encounter sustained cellular hypoxia. This can compromise CNS function and lead to permanent neuronal injury, which is a precursor for neurodegenerative disorders such as Alzheimer's disease. The proposed research is designed to determine the role of stress-activated signal transduction systems in regulating a cellular phenotype that is tolerant to hypoxic stress. We hypothesize that the novo gene expression is a major component of the adaptative/protective response to hypoxia, and that the p38 kinase stress-activated pathway plays a major role in this response. We present novel preliminary findings, which show that genes involved in cell proliferation and differentiation are regulated by hypoxia and p38. We hypothesize that these genes and the genes that encode immediate early transcription factors, and the hypoxia-sensitive potassium channels are regulated by p38 during hypoxia and play a major role in protecting neurons form hypoxia injury and neurodegenerative disease. Studies are performed in PC 12 cells, which are extremely tolerant to reduced oxygen and a widely used model for elucidating the molecular mechanisms of neural function. The objectives of the proposed research are: (1) Identify the p38 isoforms that are activated by hypoxia. Determine the effects of hypoxia on the protein kinases and small 0-proteins that lie upstream of p38. (2) Determine the role of the p38 kinase pathway on the unique hypoxia- induced regulation of cyclin A, and immediate early genes in the fos and jun families. (3) Determine the role of the p38 kinase pathway in regulating the hypoxia-induced expression of the oxygen-sensitive Kv1 .2 potassium channel.