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Mechanisms Promoting ERK-Dependent Neuronal Oxidative Toxicity

Levinthal, David Justin (2004) Mechanisms Promoting ERK-Dependent Neuronal Oxidative Toxicity. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Glutamate-induced oxidative toxicity in HT22 cells and primary immature cortical cultures provides an excellent model system for studying oxidative stress-dependent neurodegeneration. Glutamate treatment leads to cysteine and subsequent glutathione depletion, followed by the steady accumulation of reactive oxygen species (ROS). This form of cell death depends upon the persistent activation, via phosphorylation, of extracellular signal regulated kinase (ERK) kinase-1/2 (ERK-1/2) that occurs during oxidative stress. However the mechanisms responsible for this chronic activation of ERK during oxidative stress have not been well characterized. In this thesis, I demonstrate that ERK activation is dependent upon the tonic activity of the phosphatidylinositol-3-kinase (PI3K)-Akt pathway and the subsequent activation of MEK. Furthermore, the persistent ERK activation that leads to cellular toxicity can be driven by the oxidative-dependent inactivation of ERK-phosphatases. Thus the balance of activating kinase activity and inactivating phosphatase activity dynamically regulates ERK-dependent signaling and is a major determinant of neuronal cell responses to oxidative stress. The overexpression of a negative regulator of the ERK MAPK pathway, the ERK-specific phosphatase MKP3, led to protection of both HT22 cells and primary immature cortical cultures from oxidative toxicity. Furthermore, a catalytically inactive form of MKP3 (MKP3 C293S) was shown to physically restrict activate ERK to the cytoplasm. Because overexpression of MKP3 C293S was also shown to be neuroprotective, translocation of active ERK to the nucleus, but not ERK activation alone, must be required for glutamate-induced oxidative toxicity. Collectively, these results clearly place ERK activation as a necessary event that leads to neuronal cell death during oxidative stress and have revealed some unique mechanisms by which ROS accumulation drives ERK activation.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Levinthal, David
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairDeFranco, Donalddod1@pitt.eduDOD1
Committee MemberThiels,
Committee MemberAizenman, Eliasredox@pitt.eduREDOX
Committee MemberReynolds, Ianiannmda@pitt.eduIANNMDA
Committee MemberHastings, Teresahastings@bns.pitt.eduTHASTING
Committee MemberRatan,
Date: 24 September 2004
Date Type: Completion
Defense Date: 14 June 2004
Approval Date: 24 September 2004
Submission Date: 11 July 2004
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Neuroscience
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: cell death; ERK; HT22; MAPK; MKP3; neuron; neuronal cell line; oxidative stress; phosphatase; PP2A; primary cortical cultures
Other ID:, etd-07112004-190700
Date Deposited: 10 Nov 2011 19:50
Last Modified: 15 Nov 2016 13:45


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