RAC 1 MEDIATED ACTIVATION OF PROTEIN PHOSPHAT ASE-1 (PP1) BY EXTRASYNAPTIC NMDA RECEPTORS IS CRITICAL FOR SHUTTING OFF THE ACTIVATION OF CAMP/CALCIUM RESPONSE ELEMENT-BINDING PROTEIN (CREB)
Document Type
Presentation
Start Date
22-10-2010 3:00 PM
End Date
22-10-2010 4:30 PM
Description
CREB mediated gene transcription is critical for numerous cellular processes including cell survival. Cells can respond to a variety of extra-cellular signals and activate CREB through phosphorylation at serine 133 by an array of kinases. Previous studies have established that PP1 can dephosphorylate and inactivate CREB. In neurons, activation of MAPK kinase cascades by NMDA receptors opening is responsible for CREB activation. However, bath NMDA application only led to transient activation of CREB in primary cultured neurons of an age of 14 days in vitro (DIV14), while bath NMDA application in DIV? neurons led to persistent CREB activation. The underlying mechanism for this developmental regulation of CREB activation's temporal profile is not clear.
In the current study we have established a PP1 activation assay by determining the status of phosphorylation of PP1 at threonine 320. We have found that bath NMDA application led to PP1 activation in DIV 14 neurons, but not in DIV? neurons. Moreover, we have found that pretreatment of NSC 23766, a specific Rae 1 inhibitor, can block the activation of PP1 by bath NMDA application in DIV 14 neurons. More significantly, pretreatment with Rac1 inhibitor can also block the shut off of CREB activation by bath NMDA receptor activation. Bath NMDA application is known to activate both synaptic and extra-synaptic NMDA receptors. By using protocols that only activate synaptic or extra-synaptic NMDA receptors, we found that synaptic NMDA receptor opening does not activate PP1 while extra-synaptic NMDA receptor activation led to Rac1 mediated PP1 activation. Our data thus suggests that activation of extra-synaptic NMDA receptors led to a dominant Rac1-PP1 signaling pathway, dephosphorylating and inactivating CREB. C
REB mediated gene transcription is critical for cell survival. Bath NMDA application has been shown to shut off CREB activation and induce neuronal cell death. Our future goal is to determine the role of Rac-PP1 signaling pathway in neuronal degeneration. Results from our work will provide insights in potential therapeutic intervention in diseases like stroke.Supported by NIH & NSF
Recommended Citation
Hou, Hailong; Yang, Hongtian; Gu, Hua; and Siddoway, Benjamin, "RAC 1 MEDIATED ACTIVATION OF PROTEIN PHOSPHAT ASE-1 (PP1) BY EXTRASYNAPTIC NMDA RECEPTORS IS CRITICAL FOR SHUTTING OFF THE ACTIVATION OF CAMP/CALCIUM RESPONSE ELEMENT-BINDING PROTEIN (CREB)" (2010). Dr. Joseph M. Moerschbaecher, III Graduate Research Day. 10.
https://digitalscholar.lsuhsc.edu/grad_rs/2010/poster2/10
RAC 1 MEDIATED ACTIVATION OF PROTEIN PHOSPHAT ASE-1 (PP1) BY EXTRASYNAPTIC NMDA RECEPTORS IS CRITICAL FOR SHUTTING OFF THE ACTIVATION OF CAMP/CALCIUM RESPONSE ELEMENT-BINDING PROTEIN (CREB)
CREB mediated gene transcription is critical for numerous cellular processes including cell survival. Cells can respond to a variety of extra-cellular signals and activate CREB through phosphorylation at serine 133 by an array of kinases. Previous studies have established that PP1 can dephosphorylate and inactivate CREB. In neurons, activation of MAPK kinase cascades by NMDA receptors opening is responsible for CREB activation. However, bath NMDA application only led to transient activation of CREB in primary cultured neurons of an age of 14 days in vitro (DIV14), while bath NMDA application in DIV? neurons led to persistent CREB activation. The underlying mechanism for this developmental regulation of CREB activation's temporal profile is not clear.
In the current study we have established a PP1 activation assay by determining the status of phosphorylation of PP1 at threonine 320. We have found that bath NMDA application led to PP1 activation in DIV 14 neurons, but not in DIV? neurons. Moreover, we have found that pretreatment of NSC 23766, a specific Rae 1 inhibitor, can block the activation of PP1 by bath NMDA application in DIV 14 neurons. More significantly, pretreatment with Rac1 inhibitor can also block the shut off of CREB activation by bath NMDA receptor activation. Bath NMDA application is known to activate both synaptic and extra-synaptic NMDA receptors. By using protocols that only activate synaptic or extra-synaptic NMDA receptors, we found that synaptic NMDA receptor opening does not activate PP1 while extra-synaptic NMDA receptor activation led to Rac1 mediated PP1 activation. Our data thus suggests that activation of extra-synaptic NMDA receptors led to a dominant Rac1-PP1 signaling pathway, dephosphorylating and inactivating CREB. C
REB mediated gene transcription is critical for cell survival. Bath NMDA application has been shown to shut off CREB activation and induce neuronal cell death. Our future goal is to determine the role of Rac-PP1 signaling pathway in neuronal degeneration. Results from our work will provide insights in potential therapeutic intervention in diseases like stroke.Supported by NIH & NSF
Comments
See abstract book page 54