1. Objectives Methods Results Conclusion
Nuclear Membrane Integrity upon Cistaousis thought In vitro and In vivo model of Traumatic Brain Injury Nasrin Fazli٭1,2, Dr. Koorosh Shahpasand1,2 1- Royan Institute for Stem cell Biology and Technology, Tehran, Iran 2- Faculty of Basic Science and Advanced Technologies in Biology, University of Science and Culture
Objectives
Methods
Tauopathies are a class of neurodegenerative diseases associated with tau protein hyperphosphorylation and aggregation. There are several phosphorylation sites on tau but it has been shown that phosphorylated tau at threonine 231 exists in the two distinct cis and trans conformations, and that cis is highly neurotoxic. Furthermore, our initial observation have demonstrated that cis p-tau is becoming neurotoxic upon nuclear translocation. One possibility for tau translocation is nuclear membrane destruction. Thus, we herein examined the role of nuclear membrane integrity in the death of neurons before and after the cis p-Tau nuclear localization.
To examine the membrane integrity during cistauosis, we overexpressed GFP-tau and RFP-LAP (lamin associated protein) and observed the membrane as well as pathogenic GFP-tau during the translocation process. Furthermore, we studied the effect of nuclear membrane stabilization on neurodegeneration in the in vivo and in vitro conditions.
Results
We found that the nuclear membrane in SH-SY5Y and mice primary neuron during cistauosis remains naïve. Anyhow, it is being destructed after cis p-tau231 nuclear localization. Also, nuclear membrane stabilizers, including Green Tea Extract, Curcumin and Valproate Sodium suppress cell death in vitro and in vivo. Notably, there was an improvement in cognitive function of TBI mouse models.
Figure 1: Overexpressing RFP-LAP and GFP-tau under Hypoxia Stress to show nuclear membrane structure upon Cistaousis
GFP-Tau
RFP-LAP
Merge (RFP-LAP & GFP-Tau)
28 hours/Stress +
32 hours/Stress+
Figure 2:Immunofluorescence for Tau5 Antibody to determine time frame of Cis p-tau translocation to the nucleus
DAPI
TAU 5
264 h
240 h
216 h
288 h
Figure 3: MTT Assay, In vitro treatment be nuclear membrane stabilizer to reduce apoptosis rate.
Conclusion
Given that cis pT231-tau has been evaluated as a major neurotoxic factor for tauopathy disorders, it is of crucial importance to find how cis p-tau plays its pathogenic roles. We showed the nuclear membrane mediatory role in cistauosis and noticed the nuclear membrane stabilizers can suppress cis p-tau neurotoxic effects. Our findings opened new windows toward understanding tauopathy molecular mechanisms and would help us find an efficient therapeutic strategy against the devastating disorders.
Figure 4: Elevated Plus Maze, Behavioral assay to measure the effect of nuclear membrane stabilizer on brain function in mice model of Traumatic brain injury which treated by nuclear membrane stabilizers for two months.