The Journal of Neuroscience, January 1, 2001, 21(1):45-52
Blockade of NGF-Induced Neurite Outgrowth by a Dominant-Negative
Inhibitor of the Egr Family of Transcription Regulatory Factors
Yechiel
Levkovitz,
Kevin J.
O'Donovan, and
Jay M.
Baraban
Departments of Neuroscience, Psychiatry, and Behavioral Sciences,
Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
Although it is well established that members of the Egr family of
transcription regulatory factors are induced in many neuronal plasticity paradigms, it is still unclear what role, if any, they play
in this process. Because NGF stimulation of pheochromocytoma 12 cells
elicits a robust induction of Egr family members, we have investigated
their role in mediating long-term effects elicited by NGF in these
cells by using the Egr zinc finger DNA-binding domain as a selective
antagonist of Egr family-mediated transcription. We report that
expression of this Egr inhibitor construct suppresses neurite outgrowth
elicited by NGF but not by dibutyryl cAMP. To check that this
Egr inhibitor construct does not act by blocking the MEK/ERK
pathway, which is known to mediate NGF-induced neurite outgrowth, we
confirmed that the Egr inhibitor construct does not block NGF
activation of Elk1-mediated transcription, a response that is dependent
on this pathway. Conversely, inhibition of MEK does not impair Egr
family-mediated transcription. Thus, we conclude (1) that induction of
Egr family members and activation of the MEK/ERK pathway by NGF are
mediated by separate signaling pathways and (2) that both are required
to trigger neurite outgrowth induced by NGF.
Key words:
NGF; PC12 cells; Egr1; zif268; MEK; ERK
Copyright © 2001 Society for Neuroscience 0270-6474/01/21145-08$05.00/0