Cerebellar gene expression following human traumatic brain injury.

Gene expression of specific brain biomarkers offers the possibility of shedding light on the difficult molecular pathways of traumatic brain injury (TBI) and may be useful to estimate the age of trauma. Gene expression rates of cerebellar injuries are not yet sufficiently established. In 12 cases (mean age 42 years) of TBI including a pathological change in cerebellum (with known survival times ranging from immediate death to 96 h), brain tissue samples from different brain regions were analyzed with real-time polymerase chain reaction (PCR) for expression of caspase-3, tyrosine kinase receptor B (TrkB), S100B, and glial fibrillary acidic protein (GFAP) mRNA. The pH was measured to gain information about a possible correlation to RNA degradation. For comparison, corresponding brain regions were arranged from control samples of subjects that died from sudden death. We found a correlation between pH and the degradation of RNA in samples from the contralateral site, where the samples with degraded RNA have a lower pH (p<0.05). For short survival times, the expression changes of caspase-3 (p<0.05) and the expression changes of TrkB (p<0.1) in the cerebellum show a significant increase compared to the controls. The cerebellar gene expression changes seem to occur much faster and stronger compared to the other investigated regions, in particular the cerebral trauma site. These findings could make the cerebellum an important target area to study the expression changes after TBI.

Proteomic analyses of Caenorhabditis elegans dauer larvae and long-lived daf-2 mutants implicates a shared detoxification system in longevity assurance.

The insulin/insulin-like growth factor-1 (IGF-1) signaling system is a public regulator of aging in the model animals Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus. For the first time, proteomic analyses of the environmentally resistant and 'nonaging' C. elegans dauer stage and long-lived daf-2 mutants has provided a unique insight into the protein changes which mediate survival against endogenously produced toxins. These changes support a diversion of energy consumption away from anabolic processes toward enhanced cellular maintenance and detoxification processes as previously described by the 'Green Theory of Aging'. Important components of this enhanced longevity system identified in this proteomics study include the alpha-crystallin family of small heat shock proteins, anti-ROS defense systems and cellular phase II detoxification (in daf-2 only). Among those proteins involved in phase II cellular detoxification that were significantly upregulated was a Pi-class glutathione transferase (GST) CE00302. Targeting this GST with RNAi revealed compensatory regulation within the Pi-class GSTs. Furthermore, a recombinant form of the GST protein was found to detoxify and/or bind short-chain aldehydic natural toxic products of lipid peroxidation and long-chained fatty-acids at physiologically relevant concentrations, which may indicate a role in longevity.

Developmental expression and subcellular localization of glutaminyl cyclase in mouse brain.

Glutaminyl cyclase (QC) converts N-terminal glutaminyl residues into pyroglutamate (pE), thereby stabilizing these peptides/proteins. Recently, we demonstrated that QC also plays a pathogenic role in Alzheimer's disease by generating the disease-associated pE-Abeta from N-terminally truncated Abeta peptides in vivo. This newly identified function makes QC an interesting pharmacological target for Alzheimer's disease therapy. However, the expression of QC in brain and peripheral organs, its cell type-specific and subcellular localization as well as developmental profiles in brain are not known. The present study was performed to address these issues in mice. In brain, QC mRNA expression was highest in hypothalamus, followed by hippocampus and cortex. In liver, QC mRNA concentration was almost as high as in brain while lower QC mRNA levels were detected in lung and heart and very low expression levels were found in kidney and spleen. In the developmental course, stable QC mRNA levels were detected in hypothalamus from postnatal day 5 to 370. On the contrary, in cortex and hippocampus QC mRNA levels were highest after birth and declined during ontogenesis by 20-25%. These results were corroborated by immunocytochemical analysis in mouse brain demonstrating a robust QC expression in a subpopulation of lateral and paraventricular hypothalamic neurons and the labeling of a significant number of small neurons in the hippocampal molecular layer, in the hilus of the dentate gyrus and in all layers of the neocortex. Hippocampal QC-immunoreactive neurons include subsets of parvalbumin-, calbindin-, calretinin-, cholecystokinin- and somatostatin-positive GABAergic interneurons. The density of QC labeled hippocampal neurons declined during postnatal development matching the decrease in QC mRNA expression levels. Subcellular double immunofluorescent analysis localized QC within the endoplasmatic reticulum, Golgi apparatus and secretory granules, consistent with a function of QC in protein maturation and/or modification. Our results are in compliance with a role of QC in hypothalamic hormone maturation and suggest additional, yet unidentified QC functions in brain regions relevant for learning and memory which are affected in Alzheimer's disease.