The effects of death and post-mortem cold ischemia on human tissue transcriptomes

Post-mortem tissues samples are a key resource for investigating patterns of gene expression. However, the processes triggered by death and the post-mortem interval (PMI) can significantly alter physiologically normal RNA levels. We investigate the impact of PMI on gene expression using data from multiple tissues of post-mortem donors obtained from the GTEx project. We find that many genes change expression over relatively short PMIs in a tissue-specific manner, but this potentially confounding effect in a biological analysis can be minimized by taking into account appropriate covariates. By comparing ante- and post-mortem blood samples, we identify the cascade of transcriptional events triggered by death of the organism. These events do not appear to simply reflect stochastic variation resulting from mRNA degradation, but active and ongoing regulation of transcription. Finally, we develop a model to predict the time since death from the analysis of the transcriptome of a few readily accessible tissues. This work was supported by the following grants and contracts: 1) From the US NIH: Contract HHSN261200800001E (Leidos Prime contract with NCI); Contracts 10XS170 (NDRI), 10XS171 (Roswell Park Cancer Institute), 10 × 172 (Science Care Inc.), and 12ST1039 (IDOX); Contract 10ST1035 (Van Andel Institute); Contract HHSN268201000029C (Broad Institute); R01 DA006227-17 (U Miami Brain Bank) 2) Ipatimup and i3s are partially funded by the Portuguese Foundation for Science and Technology (FCT); FEDER funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalization (POCI), Portugal 2020, and by Portuguese funds through FCT/MCTES in the framework POCI-01-0145-FEDER-007274; 3) NORTE-01-0145-FEDER-000029, supported by NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); 4) FCT Fellowships SFRH/BPD/89764/2012 to PO, PD/BD/128007/2016 to AS; Salary support to PGF by POPH—QREN Type 4.2, European Social Fund and MCTES, program Investigador FCT, IF/01127/2014. 5) BIO2014-57291-R from the Spanish Ministry of Economy and Competitiveness and “Plataforma de Recursos Biomoleculares y Bioinformáticos” PT13/0001/0007 from the ISCIII, and EU H2020-INFRADEV-1-2015-1 ELIXIR-EXCELERATE (ref. 6,676559) Spanish Ministry of Economy and Competitiveness, ‘Centro de Excelencia Severo Ochoa 2013-2017’ and CERCA Programme/Generalitat de Catalunya, 7) Ministerio de Educación, Cultura y Deporte, under th