Dataset Information

Post-ischemic ubiquitination at the postsynaptic density reversibly influences the activity of ischemia-relevant kinases.

ABSTRACT: Posttranslational modifications with ubiquitin alter protein function and stability, thereby regulating cell homeostasis and viability, particularly under stress. Ischemic stroke induces protein ubiquitination at the periphery of the ischemic territory, wherein cells remain viable. Revealing the identity of ubiquitinated proteins, their cellular location, and the functional consequences of ubiquitin modification may shed light on the role of ubiquitination in ischemic injury. Here, we employed a proteomics approach to identify proteins ubiquitinated following ischemic stroke, induced by transient middle cerebral artery occlusion (tMCAO) in mice. We detected increased ubiquitination of 198 proteins, many of which localize to the postsynaptic density (PSD) of glutamatergic neurons. Among these were proteins essential for maintaining PSD architecture, such as PSD93, PSD95 and Shank3, as well as NMDA and AMPA receptor subunits. The largest enzymatic group at the PSD with high post-ischemic ubiquitination levels were kinases, such as CaMKII, PKC, Cdk5, and Pyk2, the aberrant activity of which contributes to post-ischemic neuronal death. Concurrent phospho-proteomics revealed altered phosphorylation patterns associated with the PSD, indicative of modified PSD kinase activity following stroke. CaMKII, PKC, and Cdk5 activity was decreased while Pyk2 activity was increased at the PSD after stroke, accompanied by the hypo- and hyper-phosphorylation of downstream targets, respectively. Removal of ubiquitin restored kinases’ activity to pre-stroke levels, identifying ubiquitination as the responsible molecular mechanism for post-ischemic kinase regulation. These findings unveil a previously unrecognized role of post-ischemic ubiquitination in the regulation of essential kinases involved in ischemic injury, and presents targeting ubiquitination as a potential new avenue for the treatment of ischemic stroke.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Brain

SUBMITTER: Qin Fu

LAB HEAD: Sheng Zhang

PROVIDER: PXD042951 | Pride | 2023-09-06

REPOSITORIES: Pride

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Publications

Post-ischemic ubiquitination at the postsynaptic density reversibly influences the activity of ischemia-relevant kinases.

Dhawka Luvna L Palfini Victoria V Hambright Emma E Blanco Ismary I Poon Carrie C Kahl Anja A Resch Ulrike U Bhawal Ruchika R Benakis Corinne C Balachandran Vaishali V Zhang Sheng S Iadecola Costantino C Hochrainer Karin K

bioRxiv : the preprint server for biology 20230821

Ubiquitin modifications alter protein function and stability, thereby regulating cell homeostasis and viability, particularly under stress. Ischemic stroke induces protein ubiquitination at the ischemic periphery, wherein cells remain viable, however the identity of ubiquitinated proteins is unknown. Here, we employed a proteomics approach to identify these proteins in mice undergoing ischemic stroke. The data are available in a searchable web interface ( https://hochrainerlab.shinyapps.io/Strok ...[more]

PMID: 37662420

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Project description:Astrogliosis is a hallmark of the response to brain ischemia, comprised of changes in gene expression and morphology. Hsp72 protects from cerebral ischemia, and although several mechanisms of protection have been investigated, effects on astrocyte activation are unknown. To identify potential mechanisms of protection, gene expression was assessed in mice subjected to middle cerebral artery (MCAO) or sham surgery, of either wildtype (WT) or Hsp72-overexpressing (Hsp72Tg) mice. After stroke, both genotypes exhibited genes related to cell death, stress response, and immune response. Furthermore, genes indicative of astrocyte activation, including cytoskeletal proteins and cytokines, were upregulated. To measure astrocyte activation after stroke, detailed histological and morphological analyses were performed in the cortical penumbra after stroke using unbiased stereology. Consistent with other reports, we observed a marked and persistent increase in glial fibrillary acidic protein (GFAP ) as soon as 3 hours after MCAO. In contrast, vimentin immunoreactivity appeared 12-24 hours after stroke, peaked at 72 hours, and returned to baseline after 30 days. Surprisingly, no change in overall astrocyte number was observed based on glutamine synthetase (GS) immunoreactivity. To determine if Hsp72Tg mice exhibited altered astrocyte activation compared to WT controls, morphological evaluation by fractal analysis was used. Overexpression of Hsp72 reduced astrocyte cell area, arbor area, and to a lesser extent fractal dimension, 72 hours following stroke. In conclusion, in vivo overexpression of Hsp72 alters gene expression following stroke, including genes involved in astrocyte activation, and decreases astrocyte activation acutely following MCAO. Thus, modulation of astrogliosis may be a neuroprotective mechanism exerted by Hsp72 after ischemia. A total of 10 samples were analyzed, with 5 of each genotype, wildtype (WT) and Hsp72-overexpressing (Hsp72Tg) mice. Of the 5 in each group, 3 received middle cerebral artery occlusion (MCAO) and 2 received a sham surgery. The sham samples serve as the controls for the MCAO samples in each genotype. All samples were taken from the ischemic or control hemisphere 24 hours after surgery.

Project description:1. Rationale: Stroke is still a major cause of death and disability worldwide. A better comprehension of stroke pathophysiology is fundamental to reduce its dramatic outcome. The use of high-throughput unbiased omics approaches, such as proteomics and transcriptomics, might aid to deepen the knowledge of stroke at the molecular level. Moreover, the integration of omics data is needed to depict the existing interaction between different molecular units and interpret the results in a global biological context. 2. Objective: Our aim was to identify and verify protein and gene expression changes that occur in the human brain after ischemia through an integrative approach to join and combine the information of both omics analyses. The translational potential of our results was explored in a pilot study with blood samples from ischemic stroke patients. 3. Methods and results: Proteomics and transcriptomics discovery studies were performed in human brain samples from deceased stroke patients, unveiling 128 proteins and 2716 genes significantly dysregulated after cerebral ischemia. Afterwards, integrative bioinformatics analyses joining both datasets exposed several canonical pathways altered in the ischemic area, such as neurotransmitters release or matrisome regulation, highlighting the most influential molecules in these pathways. To conduct the verification phase, 28 genes and 9 proteins were selected to be validated in independent human brain samples by means of orthogonal techniques. Our results were confirmed for NCDN, RAB3C, ST4A1, DNM1L, A1AG1, A1AT, JAM3, VTDB, ANXA1, ANXA2 and IL8. Finally, the blood circulating levels of the validated protein candidates were explored in ischemic stroke patients over the acute phase of the disease. Protein fluctuations along the first week after onset were detected for A1AG1 and A1AT. 4. Conclusion: The results presented here expand the knowledge of stroke pathology, revealing new key molecules that can be further explored as biomarkers and/or therapeutic targets of ischemic stroke.

Dataset Information

Post-ischemic ubiquitination at the postsynaptic density reversibly influences the activity of ischemia-relevant kinases.

Publications

Post-ischemic ubiquitination at the postsynaptic density reversibly influences the activity of ischemia-relevant kinases.

Similar Datasets

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