Compression alters kinase and phosphatase activity and tau and MAP2 phosphorylation transiently while inducing the fast adaptive dendritic remodeling of underlying cortical neurons.
In traumatic brain injury (TBI) there is often compression of the cerebral cortex. Using a rat epidural bead implantation model we found that mechanical compression distorted the dendrites of underlying cortical pyramidal neurons, and that the deformed dendrites regained straight morphology in 3 days. This was accompanied by a transient increase in the phosphorylation of microtubule-associated proteins (MAPs) at sites known to destabilize microtubules, including MAP2 from 30 min to 1 h, and tau from 10 min to 12 h following compression. Immunostaining confirmed that phosphorylated MAPs were concentrated at the somata and dendrites of compressed cortical pyramidal neurons. Enzymes regulating MAP phosphorylation were found to be simultaneously altered, including downregulation of protein phosphatase 2A, but not 2B, activity from 10 min to 1 day, and transient excitatory phosphorylation of extracellular signal-regulated protein kinase 1/2 and p38/mitogen-activated protein kinase. The temporal coincidence of these events suggests that alterations of phosphatase and kinase activity underlie MAP2 and tau phosphorylation, thus causing the compressed cortical neurons to remodel their dendrites, including the proximal segments. The rapid onset of these molecular changes demonstrates that compression causes cortical neurons to undergo active changes much early than expected. The large-scale structural changes that result can alter cortical function for an extended period of time.
Chen
Li-Jin
LJ
Institute of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Wang
Yueh-Jan
YJ
Tseng
Guo-Fang
GF
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D002540:Cerebral Cortex / Q000201:enzymology / Q000293:injuries / Q000378:metabolism*; D019245:Compressive Strength; D003712:Dendrites / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D011494:Protein Kinases / Q000378:metabolism*; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D015854:Up-Regulation / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism*
C489787:MAP2 protein, rat; C489131:Mapt protein, rat; D008869:Microtubule-Associated Proteins; D016875:tau Proteins; D011494:Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D019703:Calcineurin; D054648:Protein Phosphatase 2