Deep Succinylproteomics of Brain Tissues of Intracerebral Hemorrhage with Inhibition of Toll-like Receptor 4 Signaling

It is unclear how Toll-like receptor (TLR) 4 signaling affects protein succinylation in the brain after intracerebral hemorrhage (ICH). Here, we constructed a mouse ICH model to investigate the changes in ICH-associated brain protein succinylation, following a treatment with a TLR4 antagonist, TAK242, using a high-resolution mass spectrometry-based, quantitative succinyllysine proteomics approach. We characterized the prevalence of approximately 6700 succinylation events and quantified approximately 3500 sites, highlighting 139 succinyllysine site changes in 40 pathways. Further analysis showed that TAK242 treatment induced an increase of 29 succinyllysine sites on 28 succinylated proteins and a reduction of 24 succinyllysine sites on 23 succinylated proteins in the ICH brains. TAK242 treatment induced both protein hypersuccinylations and hyposuccinylations, which were mainly located in the mitochondria and cytoplasm. GO analysis showed that TAK242 treatment-induced changes in the ICH-associated succinylated proteins were mostly located in synapses, membranes and vesicles, and enriched in many cellular functions/compartments, such as metabolism, synapse, and myelin. KEGG analysis showed that TAK242-induced hyposuccinylation was mainly linked to fatty acid metabolism, including elongation and degradation. Moreover, a combined analysis of the succinylproteomic data with previously published transcriptome data revealed that most of the differentially succinylated proteins induced by TAK242 treatment were mainly distributed throughout neurons, astrocytes, and endothelial cells, and the mRNAs of seven and three succinylated proteins were highly expressed in neurons and astrocytes, respectively. In conclusion, we revealed that several TLR4 signaling pathways affect the succinylation processes and pathways in mouse ICH brains, providing new insights on the ICH pathophysiological processes. Data are available via ProteomeXchange with identifier PXD025622.