Immunohistochemical Analysis of the Ubiquitin Proteasome System and Autophagy Lysosome System Induced After Traumatic Intracranial Injury

Abstract

This study aimed to analyze how the ubiquitin proteasome system (UPS) or autophagy lysosome system (autophagy) are induced in brain tissues at different intervals after traumatic intracranial injury in humans. Injured cerebral cortices of 36 forensic autopsy cases were analyzed by immunohistochemistry using antibodies as the UPS marker (ubiquitin and lysine 48-linked polyubiquitin chains [K48]) and autophagy marker (lysine 63-linked polyubiquitin chains [K63], p62/sequestome 1 and microtubule-associated protein 1 light chain 3 [LC3]). The number of neurons and glial cells with cytoplasmic inclusions that stained positive for ubiquitin, K48, and p62 began to increase within 1 hour after intracranial injury, particularly at contusion sites. From 3.5 hours onward, an increase in cytoplasmic inclusions that stained positive for K63 and LC3 began to be detected. LC3-positive cytoplasmic inclusions were not identified after 37 days; however, the increased immunoreactivity to ubiquitin and anti-K48 antibody was maintained for 7 months. These results suggest that the UPS is activated earlier and lasts longer than autophagy, that autophagy is activated for a relatively short term (between a few hours and approximately 1 month), and that the activation occurs especially in severely damaged brain tissues following head trauma in humans.

A model of traumatic brain injury using human iPSC-derived cortical brain organoids

“…Ingenuity Pathway Analysis (Qiagen) was used to identify the top perturbed canonical pathways ( Fig 3C). Consistent with known TBI literature, we found significant changes in several pathways related to energy production 37 (glycolysis, AMPK Signaling) and protein homeostasis [38][39][40] (protein ubiquitination, sumoylation, unfolded protein response) among the top affected pathways.…”

Chaperone-Mediated Autophagy after Traumatic Brain Injury

“…It was reported previously that free ubiquitin protein levels were significantly reduced in both ipsilateral cerebral cortex and hippocampus during the periods of 1-7 days after TBI, while ubi-proteins were not increased until 3 days after TBI. 25,26 In comparison, the present study observed no significant change in the free ubiquitin and only moderate increases in ubi-proteins during the periods of 4 h to 15 days after TBI. The discrepancy is likely because more severe TBI (about 2.5 atm) was used in the previous studies than that in the present report (about 2.0 atm).…”

The New Neurometabolic Cascade of Concussion

“…These mechanisms have been implicated in Alzheimer disease, tauopathies, synucleinopathies (Parkinson disease) and ALS, to name a few, and it is not surprising that these links are now being made in TBI. Early and prolonged proteasomal activation has been proposed based upon immunohistochemical findings after severe human TBI 98 .…”