PhD Scientific Days 2021

PO_I_L: Pathology and Oncology I. Lectures

Proteomic Characterization of the Post-mortem Interval-dependent Human Tissue Degradation

Text of the abstract

Introduction
Protein degradation is one of the major processes in tissue decomposition after death. Comprehensive analyses of changes in the composition of proteins using high resolution mass spectrometry-based (MS) proteomics might provide insight into decomposition processes according to the post-mortem time interval (PTI). Here we describe the complex mechanism of protein degradation in human autopsy samples of the liver, kidney and lung.

Aims
Our aim is to find the diagnostically relevant PTI-dependent dynamics of protein decomposition in the most frequently stored tissues at routine autopsy procedures.

Methods
Patients were selected with predefined PTI (6-12-18-24-48-72-96 hours) and lack of specific diseases affecting the investigated organs. Tissue samples were immediately snap-frozen and processed for liquid chromatography-tandem MS with label-free quantification. Dynamic changes of the mass-composition were quantified in 1 µg proteome of each sample. Stable and unstable proteins were analyzed with the Gene Ontology (GO) and Reactome databases.

Results
While PTI has only minor impact on the proteome coverage, pairwise-comparisons to the reference 6h-PTI revealed significant changes in the mass-composition after 24h PTI in liver and kidney samples and after 48h PTI in lung samples.
Dynamic changes in representation of proteins in the mass-composition were different in the investigated organs. The cytoskeletal proteins in kidney tissue remained stable at the increasing time intervals whereas certain RNA-related regulators and plasma membrane associated proteins became underrepresented. In the liver, proteins of the RNA and DNA binding proteins became underrepresented while oxidoreductases and electron transfer-related proteins accumulated with the time. Contrary to the liver and kidney, proportion of the adenyl-nucleotide-related proteins (adenylyltransferases and ATPases) decreased while extracellular matrix proteins increased with the time in the mass-composition.

Conclusion
Understanding the biology behind the PTI-dependent changes of the proteome offers breathtaking opportunities for diagnostic and therapeutic improvements and paves the way for reliable protein-based diagnostics on human autopsy tissue samples.

Funding
New National Excellence Program (ÚNKP-20-3-II-SE-36); Semmelweis 250+ (EFOP-3.6.3-VEKOP-16-2017-00009)

University and Doctoral School

Semmelweis University, Doctoral School of Pathological Sciences