Brain trauma induces X-box protein 1 processing indicative of activation of the endoplasmic reticulum unfolded protein response.
Brain trauma was induced in mice using a closed head injury (CHI) model. At 1, 6 or 24 h after trauma, brains were dissected into the cortex, striatum and hippocampus. Changes in levels of processed X-box protein 1 (xbp1), glucose-regulated protein 78 (grp78), growth arrest and DNA damage-inducible gene 153 (gadd153) and heat-shock protein 70 (hsp70) mRNA, indicating impaired endoplasmic reticulum (ER) and cytoplasmic functioning, were evaluated by quantitative PCR. In the cortex, processed xbp1 mRNA levels rose to 2000% of control 1 h after CHI, and stayed high throughout the experiments. In the hippocampus and striatum, processed xbp1 mRNA levels rose in a delayed fashion, peaking at 6 h (1000% of control) and 24 h after CHI (1500% of control) respectively. Levels of grp78 mRNA were only slightly increased in the cortex 24 h after CHI (150% of control), and were unchanged or transiently decreased in the hippocampus and striatum. Levels of gadd153 mRNA did not change significantly after trauma. A transient rise in hsp70 mRNA levels was observed only in the cortex, peaking at 1 h after CHI (600% of control). Processing of xbp1 mRNA is a sign of activation of the unfolded protein response indicative of ER dysfunction. The results suggest that brain trauma induces ER dysfunction, which spreads from the ipsilateral cortex to the hippocampus and striatum. These observations may have clinical implications and should therefore be considered for future investigations on therapeutic intervention of brain injury caused by contusion-induced neurotrauma.
Paschen
Wulf
W
Laboratory of Molecular Nurology, Max-Planck-Institute for Neurological Research, Koeln, Germany. paschen@mpin-koeln.mpg.de
Yatsiv
Ido
I
Shoham
Shai
S
Shohami
Esther
E
D000818:Animals; D001522:Behavior, Animal; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001923:Brain Chemistry; D001930:Brain Injuries / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D007839:Functional Laterality; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins; D008297:Male; D051379:Mice; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D011489:Protein Denaturation; D011597:Psychomotor Performance; D012333:RNA, Messenger / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016622:Silver Staining; D013997:Time Factors; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000071717:X-Box Binding Protein 1
D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C497250:Ddit3 protein, mouse; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D018832:Molecular Chaperones; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D051742:Transcription Factor CHOP