RTP801 Is Induced in Parkinson's Disease and Mediates Neuron Death by Inhibiting Akt Phosphorylation/Activation

• Published in: The Journal of neuroscience Vol. 28; no. 53; pp. 14363 - 14371
• Main Authors: Malagelada, Cristina, Jin, Zong Hao, Greene, Lloyd A
• Format: Journal Article
• Language: English
• Published: United States Soc Neuroscience 31.12.2008; Society for Neuroscience
• Subjects: Analysis of Variance; Animals; Animals, Newborn; Cell Death - drug effects; Cell Death - physiology; Cells, Cultured; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; Green Fluorescent Proteins - genetics; Humans; Melanins - metabolism; Neurons - drug effects; Neurons - metabolism; Neurons - physiology; Oncogene Protein v-akt - metabolism; Oxidopamine - pharmacology; Parkinson Disease - metabolism; Parkinson Disease - pathology; Phosphorylation - drug effects; Rats; Serine - metabolism; Substantia Nigra - pathology; Superior Cervical Ganglion - cytology; Sympatholytics - pharmacology; Threonine - metabolism; Time Factors; Transcription Factors - metabolism; Transfection - methods
• ISSN: 0270-6474; 1529-2401; 1529-2401
• DOI: 10.1523/JNEUROSCI.3928-08.2008

Previously, we reported that RTP801, a stress regulated protein, is induced in multiple cellular models of Parkinson's disease (PD), in an animal model of PD and in dopaminergic neurons of PD patients. In cellular PD models, RTP801 is both sufficient and necessary for death. We further showed that RTP801 and PD mimetics such as 6-OHDA trigger neuron death by suppressing activation of the key kinase mammalian target of rapamycin (mTOR). Here, we report that as a consequence of mTOR signaling blockade, 6-OHDA suppresses the phosphorylation and activation of Akt, a major supporter of neuron survival. This effect is mediated by RTP801 and appears to underlie neuron death induced by 6-OHDA. Examination of postmortem dopaminergic neurons reveals a consistent depletion of phospho-Akt, but not of total Akt in PD patients. These observations support a sequential mechanism in which PD-associated stresses induce RTP801, suppress mTOR signaling, deplete phosphorylated/activated Akt and permit neuron degeneration and death.