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Conformations of tissue plasminogen activator (tPA) orchestrate neuronal survival by a crosstalk between EGFR and NMDAR.

ABSTRACT: Tissue-type plasminogen activator (tPA) is a pleiotropic serine protease of the central nervous system (CNS) with reported neurotrophic and neurotoxic functions. Produced and released under its single chain form (sc), the sc-tPA can be cleaved by plasmin or kallikrein in a two chain form, tc-tPA. Although both sc-tPA and tc-tPA display a similar fibrinolytic activity, we postulated here that these two conformations of tPA (sc-tPA and tc-tPA) could differentially control the effects of tPA on neuronal survival. Using primary cultures of mouse cortical neurons, our present study reveals that sc-tPA is the only one capable to promote N-methyl-D-aspartate receptor (NMDAR)-induced calcium influx and subsequent excitotoxicity. In contrast, both sc-tPA and tc-tPA are capable to activate epidermal growth factor receptors (EGFRs), a mechanism mediating the antiapoptotic effects of tPA. Interestingly, we revealed a tPA dependent crosstalk between EGFR and NMDAR in which a tPA-dependent activation of EGFRs leads to downregulation of NMDAR signaling and to subsequent neurotrophic effects.

SUBMITTER: Bertrand T

PROVIDER: S-EPMC4632317 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Conformations of tissue plasminogen activator (tPA) orchestrate neuronal survival by a crosstalk between EGFR and NMDAR.

Bertrand T T Lesept F F Chevilley A A Lenoir S S Aimable M M Briens A A Hommet Y Y Bardou I I Parcq J J Vivien D D

Cell death & disease 20151015

Tissue-type plasminogen activator (tPA) is a pleiotropic serine protease of the central nervous system (CNS) with reported neurotrophic and neurotoxic functions. Produced and released under its single chain form (sc), the sc-tPA can be cleaved by plasmin or kallikrein in a two chain form, tc-tPA. Although both sc-tPA and tc-tPA display a similar fibrinolytic activity, we postulated here that these two conformations of tPA (sc-tPA and tc-tPA) could differentially control the effects of tPA on neu ...[more]

PMID: 26469972

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Project description:Background and Purpose- Thrombolytic treatment of acute ischemic stroke with tPA (tissue-type plasminogen activator) is hampered by its narrow therapeutic window and potential hemorrhagic complication. Vepoloxamer is a nonionic surfactant that exerts potent hemorheologic and antithrombotic properties in various thrombotic diseases. The current study investigated the effect of vepoloxamer on tPA treatment in a rat model of embolic stroke. Methods- Male Wistar rats subjected to embolic middle cerebral artery occlusion were treated with the combination of vepoloxamer and tPA, vepoloxamer alone, tPA alone, or saline initiated 4 hours after middle cerebral artery occlusion. Results- Monotherapy with tPA did not reduce infarct volume, and adversely potentiated microvascular thrombosis and vascular leakage compared with the saline treatment. Vepoloxamer monotherapy reduced infarct volume by 25% and improved brain perfusion. However, the combination treatment with vepoloxamer and tPA significantly reduced infarct volume by 32% and improved neurological function, without increasing the incidence of gross hemorrhage. Compared with vepoloxamer alone, the combination treatment with vepoloxamer and tPA robustly reduced secondary thrombosis and tPA-augmented microvascular leakage and further improved brain perfusion, which was associated with substantial reductions of serum active PAI-1 (plasminogen activator inhibitor-1) level and tPA-upregulated PAI-1 in the ischemic brain. Mechanistically, exosomes derived from platelets of ischemic rats treated with tPA-augmented cerebral endothelial barrier permeability and elevated protein levels of PAI-1 and TF (tissue factor) in the endothelial cells, whereas exosomes derived from platelets of rats subjected to the combination treatment with vepoloxamer and tPA diminished endothelial permeability augmented by tPA and fibrin and reduced PAI-1 and TF levels in the endothelial cells. Conclusions- The combination treatment with vepoloxamer and tPA exerts potent thrombolytic effects in rats subjected to acute ischemic stroke. Vepoloxamer reduces tPA-aggravated prothrombotic effect of platelet-derived exosomes on cerebral endothelial cells, which may contribute to the therapeutic effect of the combination treatment.

Project description:Background and Purpose- Telemedicine is increasingly utilized for intravenous tPA (tissue-type plasminogen activator) delivery. The comparative safety of leaving tPA-treated patients at a presenting (spoke) hospital (drip-and-stay) or transferring patients to a central treating (hub) hospital (drip-and-ship) is not established. We sought to compare outcomes between drip-and-ship and drip-and-stay patients treated with tPA via telemedicine. We hypothesized that there would be no differences in short-term outcomes of in-hospital mortality, length of stay, or discharge disposition or in 90-day outcomes between groups. Methods- We retrospectively identified patients treated with tPA at 17 spoke hospitals between September 2015 and December 2016. Demographic, clinical, and outcome data were obtained from a prospective telemedicine registry. We used negative binomial, multinomial, and logistic regression analyses to evaluate length of stay, discharge disposition, and inpatient mortality, respectively. We compared the proportion of patients with 90-day modified Rankin Scale score <2 by group. Results- Among 430 tPA-treated patients, 232 (53.9%) were transferred to the hub after treatment. The median arrival National Institutes of Health Stroke Scale score was higher for drip-and-ship (10; interquartile range, 5-18) compared with drip-and-stay patients (6; interquartile range, 4-10; P<0.001). Unadjusted length of stay was longer in drip-and-stay patients (incidence rate ratio, 0.82; 95% CI, 0.71-0.95). There were no significant differences in adjusted length of stay, hospital mortality, or discharge disposition. Among the 64% of patients with complete 90-day modified Rankin Scale score, the proportion with good outcomes (modified Rankin Scale score <2) did not differ between groups. Conclusions- We found no differences in measured outcomes between drip-and-ship and drip-and-stay patients treated in our network, although our study may be underpowered to detect small differences.

Project description:Background and Purpose- Stroke is a leading cause of disability worldwide, mainly affecting the elderly. However, preclinical studies in aged ischemic animals are limited. N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) is a naturally occurring tetrapeptide with vascular-protective properties. The present study investigated the effect of AcSDKP on tPA (tissue-type plasminogen activator)-induced thrombolysis in aged rats after ischemic stroke. Methods- Aged male rats (18 months) were subjected to embolic middle cerebral artery occlusion. Rats subjected to 4 hours of middle cerebral artery occlusion were randomized into the following groups: (1) AcSDKP; (2) tPA; (3) AcSDKP in combination with tPA; and (4) saline. Neurological deficits, cerebral microvascular patency and integrity, and infarction were examined at 1 day and 7 days after middle cerebral artery occlusion. In vitro experiments were performed to examine the effect of AcSDKP on aged cerebral endothelial cell permeability. Results- Compared with saline, AcSDKP, or tPA as monotherapy did not have any therapeutic effects, whereas AcSDKP in combination with tPA significantly reduced cerebral tissue infarction and improved neurological outcome without increasing cerebral hemorrhage. Concurrently, the combination treatment significantly augmented microvascular perfusion and reduced thrombosis and blood-brain barrier leakage. In vitro, compared with cerebral endothelial cells from ischemic adult rats, the endothelial cells from ischemic aged rats exhibited significantly increased leakage. AcSDKP suppressed tPA-induced aged endothelial cell leakage and reduced expression of ICAM-1 (intercellular adhesion molecule 1) and NF (nuclear factor)-κB. Conclusions- The present study provides evidence for the therapeutic efficacy of AcSDKP in combination tPA for the treatment of embolic stroke in aged rats at 4 hours after stroke onset. AcSDKP likely acts on cerebral endothelial cells to enhance the benefits of tPA by increasing tissue perfusion and augmenting the integrity of the blood-brain barrier. Visual Overview- An online visual overview is available for this article.

Dataset Information

Conformations of tissue plasminogen activator (tPA) orchestrate neuronal survival by a crosstalk between EGFR and NMDAR.

Publications

Conformations of tissue plasminogen activator (tPA) orchestrate neuronal survival by a crosstalk between EGFR and NMDAR.

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