Stressed neurons protect themselves by a tissue-type plasminogen activator-mediated EGFR-dependent mechanism.
Ontology highlight
ABSTRACT:
SUBMITTER: Lemarchand E
PROVIDER: S-EPMC4815983 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Ischemia of the heart, brain, and limbs is a leading cause of morbidity and mortality worldwide. Treatment with tissue type plasminogen activator (tPA) can dissolve blood clots and can ameliorate the clinical outcome in ischemic diseases. But the underlying mechanism by which tPA improves ischemic tissue regeneration is not well understood. Bone marrow (BM)-derived myeloid cells facilitate angiogenesis during tissue regeneration. Here, we report that a serpin-resistant form of tPA by activating the extracellular proteases matrix metalloproteinase-9 and plasmin expands the myeloid cell pool and mobilizes CD45(+)CD11b(+) proangiogenic, myeloid cells, a process dependent on vascular endothelial growth factor-A (VEGF-A) and Kit ligand signaling. tPA improves the incorporation of CD11b(+) cells into ischemic tissues and increases expression of neoangiogenesis-related genes, including VEGF-A. Remarkably, transplantation of BM-derived tPA-mobilized CD11b(+) cells and VEGFR-1(+) cells, but not carrier-mobilized cells or CD11b(-) cells, accelerates neovascularization and ischemic tissue regeneration. Inhibition of VEGF signaling suppresses tPA-induced neovascularization in a model of hind limb ischemia. Thus, tPA mobilizes CD11b(+) cells from the BM and increases systemic and local (cellular) VEGF-A, which can locally promote angiogenesis during ischemic recovery. tPA might be useful to induce therapeutic revascularization in the growing field of regenerative medicine.
| S-EPMC2879105 | biostudies-literature
Project description:The structural events taking place during the reaction between PAI-1 (plasminogen-activator inhibitor 1) and the plasminogen activators sc-tPA (single-chain tissue plasminogen activator) and tc-tPA (two-chain tissue plasminogen activator) were studied. Complexes were formed by mixing sc-tPA or tc-tPA with PAI-1 in slight excess (on an activity basis). The complexes were purified from excess PAI-1 by affinity chromatography on fibrin-Sepharose. Examination of the purified complexes by SDS/polyacrylamide-gel electrophoresis (SDS/PAGE) and N-terminal amino acid sequence analysis demonstrated that a stoichiometric 1:1 complex is formed between PAI-1 and both forms of tPA. Data obtained from both complexes revealed the amino acid sequences of the parent molecules and, in addition, a new sequence: Met-Ala-Pro-Glu-Glu-. This sequence is found in the C-terminal portion of the intact PAI-1 molecule and thus locates the reactive centre of PAI-1 to Arg346-Met347. The proteolytic activity of sc-tPA is demonstrated by its capacity to cleave the 'bait' peptide bond in PAI-1. The complexes were inactive and dissociated slowly at physiological pH and ionic strength, but rapidly in aq. NH3 (0.1 mol/l). Amidolytic tPA activity was generated on dissociation of the complexes, corresponding to 0.4 mol of tPA/mol of complex. SDS/PAGE of the dissociated complexes indicated a small decrease in the molecular mass of PAI-1, in agreement with proteolytic cleavage of the 'bait' peptide bond during complex-formation.
| S-EPMC1136620 | biostudies-other
Project description:Patients with coronavirus disease-19 (COVID-19) are at high risk for thrombotic arterial and venous occlusions. However, bleeding complications have also been observed in some patients. Understanding the balance between coagulation and fibrinolysis will help inform optimal approaches to thrombosis prophylaxis and potential utility of fibrinolytic-targeted therapies. 118 hospitalized COVID-19 patients and 30 healthy controls were included in the study. We measured plasma antigen levels of tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) and performed spontaneous clot-lysis assays. We found markedly elevated tPA and PAI-1 levels in patients hospitalized with COVID-19. Both factors demonstrated strong correlations with neutrophil counts and markers of neutrophil activation. High levels of tPA and PAI-1 were associated with worse respiratory status. High levels of tPA, in particular, were strongly correlated with mortality and a significant enhancement in spontaneous ex vivo clot-lysis. While both tPA and PAI-1 are elevated among COVID-19 patients, extremely high levels of tPA enhance spontaneous fibrinolysis and are significantly associated with mortality in some patients. These data indicate that fibrinolytic homeostasis in COVID-19 is complex with a subset of patients expressing a balance of factors that may favor fibrinolysis. Further study of tPA as a biomarker is warranted.
| S-EPMC7810990 | biostudies-literature
Project description: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.
| S-EPMC4632317 | biostudies-literature
Project description:Tissue-type plasminogen activator (t-PA), initially characterized for its critical role in fibrinolysis, also has key functions in both physiologic and pathologic processes in the CNS. Neuroserpin (NSP) is a t-PA specific serine protease inhibitor (serpin) found almost exclusively in the CNS that regulates t-PA's proteolytic activity and protects against t-PA mediated seizure propagation and blood-brain barrier disruption. This report demonstrates that NSP inhibition of t-PA varies profoundly as a function of pH within the biologically relevant pH range for the CNS, and reflects the stability, rather than the formation of NSP: t-PA acyl-enzyme complexes. Moreover, NSP differentiates between the zymogen-like single chain form (single chain t-PA, sct-PA) and the mature protease form (two chain t-PA, tct-PA) of t-PA, demonstrating different pH profiles for protease inhibition, different pH ranges over which catalytic deacylation occurs, and different pH dependent profiles of deacylation rates for each form of t-PA. NSP's pH dependent inhibition of t-PA is not accounted for by differential acylation, and is specific for the NSP-t-PA serpin-protease pair. These results demonstrate a novel mechanism for the differential regulation of the two forms of t-PA in the CNS, and suggest a potential specific regulatory role for CNS pH in controlling t-PA proteolytic activity.
| S-EPMC4908126 | biostudies-literature
Project description:NMDA receptors (NMDARs) play a critical role in neurotransmission, acting as essential mediators of many forms of synaptic plasticity, and also modulating aspects of development, synaptic transmission and cell death. NMDAR-induced responses are dependent on a range of factors including subunit composition and receptor location. Tissue-type plasminogen activator (tPA) is a serine protease that has been reported to interact with NMDARs and modulate NMDAR activity. In this study we report that tPA inhibits NMDAR-mediated changes in intracellular calcium levels in cultures of primary hippocampal neurons stimulated by low (5 μM) but not high (50 μM) concentrations of NMDA. tPA also inhibited changes in calcium levels stimulated by presynaptic release of glutamate following treatment with bicucculine/4-aminopyridine (4-AP). Inhibition was dependent on the proteolytic activity of tPA but was unaffected by α2-antiplasmin, an inhibitor of the tPA substrate plasmin, and receptor-associated protein (RAP), a pan-ligand blocker of the low-density lipoprotein receptor, two proteins previously reported to modulate NMDAR activity. These findings suggest that tPA can modulate changes in intracellular calcium levels in a subset of NMDARs expressed in cultured embryonic hippocampal neurons through a mechanism that involves the proteolytic activity of tPA and synaptic NMDARs.
| S-EPMC4598481 | biostudies-literature
Project description:Tissue plasminogen activator (tPA) is a serine protease involved in the degradation of blood clots through the activation of plasminogen to plasmin. Here we report on the identification of tPA as a specific protease able to activate platelet-derived growth factor C (PDGF-C). The newly identified PDGF-C is secreted as a latent dimeric factor (PDGF-CC) that upon proteolytic removal of the N-terminal CUB domains becomes a PDGF receptor alpha agonist. The CUB domains in PDGF-CC directly interact with tPA, and fibroblasts from tPA-deficient mice fail to activate latent PDGF-CC. We further demonstrate that growth of primary fibroblasts in culture is dependent on a tPA-mediated cleavage of latent PDGF-CC, generating a growth stimulatory loop. Immunohistochemical analysis showed similar expression patterns of PDGF-C and tPA in developing mouse embryos and in tumors, indicating both autocrine and paracrine modes of activation of PDGF receptor-mediated signaling pathways. The identification of tPA as an activator of PDGF signaling establishes a novel role for the protease in normal and pathological tissue growth and maintenance, distinct from its well-known role in plasminogen activation and fibrinolysis.
| S-EPMC522796 | biostudies-literature
Project description:BACKGROUND:The necessity for rapid evaluation and treatment of acute ischemic stroke with intravenous tPA (tissue-type plasminogen activator) may increase the risk of administrating tPA to patients presenting with noncerebrovascular conditions that closely resemble stroke (stroke mimics). However, there are limited data on thrombolysis safety in stroke mimics. METHODS AND RESULTS:Using data from the Get With The Guidelines-Stroke Registry, we identified 72?582 patients with suspected ischemic stroke treated with tPA from 485 US hospitals between January 2010 and December 2017. We documented the use of tPA in stroke mimics, defined as patients who present with stroke-like symptoms, but after workup are determined not to have suffered from a stroke or transient ischemic attack, and compared characteristics and outcomes in stroke mimics versus those with ischemic stroke. Overall, 3.5% of tPA treatments were given to stroke mimics. Among them, 38.2% had a final nonstroke diagnoses of migraine, functional disorder, seizure, and electrolyte or metabolic imbalance. Compared with tPA-treated true ischemic strokes, tPA-treated mimics were younger (median 54 versus 71 years), had a less severe National Institute of Health Stroke Scale (median 6 versus 8), and a lower prevalence of cardiovascular risk factors, except for a higher prevalence of prior stroke/transient ischemic attack (31.3% versus 26.1%, all P<0.001). The rate of symptomatic intracranial hemorrhage was lower in stroke mimics (0.4%) as compared with 3.5% in ischemic strokes (adjusted odds ratio, 0.29; 95% CI, 0.17-0.50). In-hospital mortality rate was significantly lower in stroke mimics (0.8% versus 6.2%, adjusted odds ratio, 0.31; 95% CI, 0.20-0.49). Patients with stroke mimics were more likely to be discharged to home (83.8% versus 49.3%, adjusted odds ratio, 2.97; 95% CI, 2.59-3.42) and to ambulate independently at discharge (78.6% versus 50.6%, adjusted odds ratio, 1.86; 95% CI, 1.61-2.14). CONCLUSIONS:In this large cohort of patients treated with tPA, relatively few patients who received tPA for presumed stroke were ultimately not diagnosed with a stroke or transient ischemic attack. The complication rates associated with tPA in stroke mimics were low. Despite the potential risk of administering tPA to stroke mimics, opportunity remains for continued improvement in the rapid and accurate diagnosis and treatment of ischemic stroke.
| S-EPMC6699639 | biostudies-literature
Project description:The molecular mechanisms underlying cerebral angiogenesis have not been fully investigated. Using primary mouse brain endothelial cells (MBECs) and a capillary-like tube formation assay, we investigated whether the sonic hedgehog (Shh) signaling pathway is coupled with the plasminogen/plasmin system in mediating cerebral angiogenesis. We found that incubation of MBECs with recombinant human Shh (rhShh) substantially increased the tube formation in naïve MBECs. This was associated with increases in tissue plasminogen activator (tPA) activation and reduction of plasminogen activator inhibitor 1 (PAI-1). Blockage of the Shh pathway with cyclopamine abolished the induction of tube formation and the effect of rhShh on tPA and PAI-1. Addition of PAI-1 reduced rhShh-augmented tube formation. Genetic ablation of tPA in MBECs impaired tube formation and downregulated of vascular endothelial growth factor (VEGF) and angiopoietin 1 (Ang1). Addition of rhShh to tPA-/- MBECs only partially restored the tube formation and upregulated Ang1, but not VEGF, although rhShh increased VEGF and Ang1 expression on wild-type MBECs. Complete restoration of tube formation in tPA-/- MBECs was observed only when both exogenous Shh and tPA were added. The present study provides evidence that tPA and PAI-1 contribute to Shh-induced in vitro cerebral angiogenesis.
| S-EPMC3303815 | biostudies-literature
Project description:INTRODUCTION:Thrombolysis with intravenous tissue plasminogen activator (tPA) is the only FDA approved treatment for patients with acute ischemic stroke, but its use is limited by narrow therapeutic window, selective efficacy, and hemorrhagic complication. In the past two decades, extensive efforts have been undertaken to extend its therapeutic time window and explore alternative thrombolytic agents, but both show little progress. Nanotechnology has emerged as a promising strategy to improve the efficacy and safety of tPA. AREAS COVERED:We reviewed the biology, thrombolytic mechanism, and pleiotropic functions of tPA in the brain and discussed current applications of various nanocarriers intended for the delivery of tPA for treatment of ischemic stroke. Current challenges and potential further directions of t-PA-based nanothrombolysis in stroke therapy are also discussed. EXPERT OPINION:Using nanocarriers to deliver tPA offers many advantages to enhance the efficacy and safety of tPA therapy. Further research is needed to characterize the physicochemical characteristics and in vivo behavior of tPA-loaded nanocarriers. Combination of tPA based nanothrombolysis and neuroprotection represents a promising treatment strategy for acute ischemic stroke. Theranostic nanocarriers co-delivered with tPA and imaging agents are also promising for future stroke management.
| S-EPMC5780255 | biostudies-literature