Methyl- and acetyltransferases are stable epigenetic markers postmortem

Postmortem brain tissue has been reported to be suitable to delineate regional pattern of possible disturbances underlying epigenetic functionality. However, from many parameters that have been detected in postmortem brain regions it is noteworthy that an effect of postmortem interval (PMI), storage time and premortem parameters should not be underestimated. Our previous investigation revealed that tryptophan (TRP) levels in postmortem brain tissue is affected by PMI and storage time. Since, alteration in TRP levels are assumed to be due to protein degradation, we further investigated whether TRP correlates to variables such as RNA, proteins and DNA modulators. In addition, we aimed to elucidate whether established postmortem variables may influence epigenetic parameters. These were investigated in well characterized postmortem human brain tissue originating from the European Brain Bank consortium II (BNEII). We could confirm previous findings, in which some protein levels alter because of prolonged PMI. Similarly, we demonstrated an influence of increased storage period on TRP levels, which might indicate degradation of proteins. Still not all proteins degrade in a similar manner, therefore a specific analysis for the protein of interest would be recommended. We found that methyltransferase- and acetyltransferase-activities were relatively preserved with PMI and storage duration. In conclusion, preservation of acetyltransferase- and methyltransferase-activities provides possible evidence of stability for epigenetic studies using postmortem tissue.