Neuroprotection against Traumatic Brain Injury by a Peptide Derived from the Collapsin Response Mediator Protein 2 (CRMP2)

Abstract

Background: CRMP2 is an axonal guidance protein that has been linked to NMDA receptor-mediated excitotoxicity. Results: A CRMP2 peptide protects against NMDA receptor-mediated excitotoxicity in vitro and in vivo following a traumatic brain injury. Conclusion: CRMP2 is a novel target for neuroprotection. Significance: Targeting CRMP2 could lead to development of neurotherapeutics against traumatic brain injury as well as other neuronal insults.

Collapsin Response Mediator Protein 2 (CRMP2) Interacts with N-Methyl-d-aspartate (NMDA) Receptor and Na+/Ca2+ Exchanger and Regulates Their Functional Activity

“…In our previous study, we had also reported that TAT-CBD3, in an activity-dependent manner, down-regulated surface expression of NR2B-containing NMDAR in dendritic spines (16). Consistent with this, in our present study, we found that TAT-CBD3 disrupts the CRMP2-NMDAR interaction (Fig.…”

“…The immunocaptured complexes were then washed three times with lysis buffer before being heated at 70°C in equal volumes of SDS loading dye (Invitrogen). Samples were then processed by immunoblotting as described previously (5,16). Blots were probed with anti-NCX1 (NCX1 mAb R3F1), anti-NCX3 (NCX3 polyclonal antibody 95209), anti-NR2B (BD Biosciences), or anti-CRMP-2 (Sigma-Aldrich) (all 1:1000).…”

“…2, A, C, and D): from a peak of 1.03 Ϯ 0.05 M to 0.17 Ϯ 0.05 M cytosolic Ca 2ϩ with TAT-CBD3 (p Ͻ 0.01, n ϭ 5 individual experiments with a total of 107 analyzed neurons) and from a peak of 1.15 Ϯ 0.05 M to 1.10 Ϯ 0.07 M cytosolic Ca 2ϩ with CBD3 without TAT (p Ͼ 0.05, n ϭ 5 individual experiments with a total of 98 analyzed neurons). Previously, we established an IC 50 for the neuroprotective action of TAT-CBD3 to be about 2 M and found that 10 M TAT-CBD3 provided maximal protection against glutamate excitotoxicity (16). Therefore, in the present study, we used 10 M TAT-CBD3.…”

“…It has been shown that TAT-CBD3 disrupts interaction of CRMP2 with CaV2.2, leading to its internalization and a decrease in ion currents mediated by this channel (35). In our previous paper, using a pH-sensitive fluorescent NR2B sensor, we showed that TAT-CBD3 decreases surface expression of NMDAR in dendritic spines (16), but it remained unclear whether TAT-CBD3 disrupts a CRMP2-NMDAR interaction. It was also unknown whether CRMP2 interacts with NCX and whether TAT-CBD3 affects NCX rev activity.…”

“…The regulation of Ca 2ϩ homeostasis in neurons exposed to glutamate is complex, and all factors involved in this regulation are not yet fully understood. Recently, we found that collapsin response mediator protein 2 (CRMP2), a phosphoprotein traditionally regarded as a regulator of axon guidance and neurite outgrowth (13)(14)(15), is also involved in regulation of cytosolic Ca 2ϩ in neurons exposed to glutamate (16). In this study, we demonstrated that CBD3 peptide, a 15-amino acid fragment of CRMP2, fused to the TAT cell-penetrating motif of the HIV-1 protein (TAT-CBD3), decreased surface expression of NMDAR in dendritic spines, antagonized glutamate-induced Ca 2ϩ dysregulation, and protected brain tissue against ischemic damage (16).…”