Influence of GENE-X1 promotor methylation on the susceptibility to develop PTSD
AbstractTraumatic events are a prevalent and high risk factor to develop psychiatric disorder like post traumatic stress disorder (PTSD). However, people differ strictly in the susceptibility or resilience to develop such disorders. The exact underlying mechanisms are unknown, but epigenetic mechanisms, such as DNA methylation might play a major role. This was demonstrated by a recent study from our group, who showed significant hypomethylation of GENE-X in the blood of subjects with PTSD. To study brain methylation patterns, the protein expression in PTSD related brain areas of social defeat (SD) mice was compared to control mice (CTR). Expression was visualized by immunohistochemistry (biotin, ABC-kit, DAB), on human tissue immunofluorescence (biotin, streptavidin) was conducted too. The GENE-X antibody was demonstrated to be specific, since the signal was reduced when performing a pre-incubation with the blocking peptide. Double labelled fluorescence showed GENE-X expression in human temporal neocortex in the cytoplasm and nucleus of neurons, and to a lower extend in astrocytic cytoplasm The staining on SD and CTR mice tissue gave no results about expression sites. This problem was expected to be caused by incorrect fixation of the brain tissue. To conclude, indirect immunohistochemistry allowed visualization of specific GENE-X expression in the human brain. However, the research on the human tissue is not related to stress. Therefore, further research on SD versus CTR material is needed, to prove a causal link between GENE-X hypomethylation in the brain and increased susceptibility to develop PTSD.
Zannas AS, Provençal N, Binder EB. Epigenetics of Posttraumatic Stress Disorder: Current Evidence, Challenges, and Future Directions. Biological Psychiatry.
Cahill CM, McClellan KA, Morinville A, Hoffert C, Hubatsch D, O’Donnell D, et al. Immunohistochemical distribution of delta opioid receptors in the rat central nervous system: Evidence for somatodendritic labeling and antigen-specific cellular compartmentalization. The Journal of Comparative Neurology. 2001;440(1):65-84.
Schnell SA, Staines WA, Wessendorf MW. Reduction of lipofuscin-like autofluorescence in fluorescently labeled tissue. Journal of Histochemistry & Cytochemistry. 1999;47(6):719-30.
Herculano-Houzel S. The glia/neuron ratio: how it varies uniformly across brain structures and species and what that means for brain physiology and evolution. Glia. 2014;62(9):1377-91.
Werner M, Chott A, Fabiano A, Battifora H. Effect of formalin tissue fixation and processing on immunohistochemistry. Am J Surg Pathol. 2000;24(7):1016-9.