Project description:Recombinant tissue-type plasminogen activator (tPA) is the fibrinolytic drug of choice to treat stroke patients. However, a growing body of evidence indicates that besides its beneficial thrombolytic role, tPA can also have a deleterious effect on the ischaemic brain. Although ageing influences stroke incidence, complications and outcome, age-dependent relationships between endogenous tPA and stroke injuries have not been investigated yet. Here, we report that ageing is associated with a selective lowering of brain tPA expression in the murine brain. Moreover, our results show that albumin D site-binding protein (DBP) as a key age-associated regulator of the neuronal transcription of tPA. Additionally, inhibition of DBP-mediated tPA expression confers in vitro neuroprotection. Accordingly, reduced levels of tPA in old mice are associated with smaller excitotoxic/ischaemic injuries and protection of the permeability of the neurovascular unit during cerebral ischaemia. Likewise, we provide neuroradiological evidence indicating the existence of an inverse relationship between age and the volume of the ischaemic lesion in patients with acute ischaemic stroke. Together, these results indicate that the relationship among DBP, tPA and ageing play an important role in the outcome of cerebral ischaemia.
Project description:Runx1 is a transcription factor that plays a key role in determining the proliferative and differential state of multiple cell types, during both development and adulthood. Here, we report how runx1 is specifically upregulated at the injury site during zebrafish heart regeneration, but unexpectedly, absence of runx1 results in enhanced regeneration. Using single cell sequencing, we found that the wild-type injury site consists of Runx1-positive endocardial cells and thrombocytes that express smooth muscle and collagen genes without differentiating into myofibroblasts. Both these populations are absent in runx1 mutants, resulting in a less collagenous and fibrinous scar. The reduction in fibrin in the mutant is further explained by reduced myofibroblast formation and by upregulation of components of the fibrin degradation pathway, including plasminogen receptor Annexin 2A as well as downregulation of plasminogen activator inhibitor serpine1 in myocardium and endocardium, resulting in increased levels of Plasminogen. In addition, this we also find enhanced myocardial proliferation as well as increased myocardial survival in the mutant. Our findings suggest that Runx1 controls the regenerative response of multiple cardiac cell-types and that targeting Runx1 is a novel therapeutic strategy to induce endogenous heart repair.
Project description:Reducing sugars can covalently react with proteins to generate a heterogeneous and complex group of compounds called advanced glycation end products (AGEs). AGEs are generally considered as pathogenic molecules, mediating a pro-inflammatory response and contributing to the development of a number of human diseases. However, the intrinsic function of AGEs remains to be elucidated. We now provide multiple lines of evidence showing that AGEs can specifically bind a cell-surface protein and regulate its functions. To identify cellular binding partners for AGEs, we used dehydroascorbic acid (DHA)-modified serum albumins as one of the AGEs to screen for binding proteins in the lipid raft fraction prepared from mouse splenocytes and identified histone localized on the cell-surface as an AGE-binding protein. Histone ubiquitously recognized AGEs, including proteins modified with glucose and its metabolites. AGEs inhibited the binding of plasminogen to the histone component H2B which functions as a cell-surface plasminogen receptor on monocytes/macrophages. Moreover, AGEs regulated the recruitment of monocytes/macrophage to the site of inflammation. Our discovery of histone as a cell-surface receptor for AGEs suggests that, beside our common concept of AGEs as danger-associated molecular patterns mediating a pro-inflammatory response, they may also be involved in the homeostatic response via binding to histone.
Project description:Plasminogen, the zymogen of plasmin, is a glycoprotein involved in fibrinolysis and a wide variety of other physiological processes. Plasminogen dysregulation has been implicated in a range of diseases. Classically, human plasminogen is categorized into two types based on the presence (type I) or absence (type II) of a single N-linked glycan, supposedly having different functional features. Using high-resolution native mass spectrometry (native MS), we uncover that the proteoform profiles of plasminogen (and plasmin) are substantially more extensive than this simple binary classification. In samples derived from human plasma, we identified up to 14 distinct proteoforms of human plasminogen, including a novel, highly abundant phosphorylation site at Ser339. To elucidate potential functional effects of these post-translational modifications, we performed proteoform-resolved kinetic analyses of the plasminogen-to-plasmin conversion using a canonical activator. This conversion is thought to involve at least two independent cleavage events: one to remove the N-terminal peptide, and another to form the active catalytic site. Our analyses reveal that these processes are not independent but are instead tightly regulated and occur in a step-wise order. Notably, N-terminal cleavage at the canonical site (Lys77) does not occur directly from intact plasminogen. Instead, an activation intermediate corresponding to cleavage at Arg68 is initially produced, which only then is further processed to the canonical Lys77 product. Based on our results, we propose a new categorization system for human plasminogen isoforms. This work highlights the capacity of high-resolution native MS to reveal new aspects of structure, even in frequently-studied serum glycoproteins.
Project description:Extrahepatic cholestasis leads to complex injury and repair processes that result in bile infarct formation, neutrophil infiltration, cholangiocyte and hepatocyte proliferation, extracellular matrix remodeling, and fibrosis. To identify early molecular mechanisms of injury and repair after bile duct obstruction, microarray analysis was performed on liver tissue 24 hours after bile duct ligation (BDL) or sham surgery. The most upregulated gene identified encodes plasminogen activator inhibitor 1 (PAI-1, Serpine 1), a protease inhibitor that blocks urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activity. Because PAI-1, uPA, and tPA influence growth factor and cytokine processing as well as extracellular matrix remodeling, we evaluated the role of PAI-1 in cholestatic liver injury by comparing the injury and repair processes in wild-type (WT) and PAI-1-deficient (PAI-1-/-) mice after BDL. PAI-1-/- mice had fewer and smaller bile infarcts, less neutrophil infiltration, and higher levels of cholangiocyte and hepatocyte proliferation than WT animals after BDL. Furthermore, PAI-1-/- mice had higher levels of tPA activation and mature hepatocyte growth factor (HGF) after BDL than WT mice, suggesting that PAI-1 effects on HGF activation critically influence cholestatic liver injury. This was further supported by elevated levels of c-Met and Akt phosphorylation in PAI-1-/- mice after BDL. In conclusion, PAI-1 deficiency reduces liver injury after BDL in mice. These data suggest that inhibiting PAI-1 might attenuate liver injury in cholestatic liver diseases. Total RNA isolated using TRI Reagent (Sigma, St. Louis, MO) was purified with an RNeasy mini kit (Qiagen, Valencia, CA). Twenty micrograms cRNA was hybridized to a mouse GeneChip (U74Av2, Affymetrix, Santa Clara, CA) at the Siteman Cancer Center GeneChip facility as described by the manufacturer. Analyses used one mouse per chip. Gene expression changes were analyzed using Affymetrix MicroArray Suite 4.0 and GeneChip 3.1 Expression Analysis and Statistical Algorithms (Affymetrix). The complete methodology and full data sets for all 6 analyzed chips are available at http://bioinformatics.wustl.edu.beckerproxy.wustl.edu This study compares the injury and repair processed in wild-type mice after BDL.
Project description:Extrahepatic cholestasis leads to complex injury and repair processes that result in bile infarct formation, neutrophil infiltration, cholangiocyte and hepatocyte proliferation, extracellular matrix remodeling, and fibrosis. To identify early molecular mechanisms of injury and repair after bile duct obstruction, microarray analysis was performed on liver tissue 24 hours after bile duct ligation (BDL) or sham surgery. The most upregulated gene identified encodes plasminogen activator inhibitor 1 (PAI-1, Serpine 1), a protease inhibitor that blocks urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activity. Because PAI-1, uPA, and tPA influence growth factor and cytokine processing as well as extracellular matrix remodeling, we evaluated the role of PAI-1 in cholestatic liver injury by comparing the injury and repair processes in wild-type (WT) and PAI-1-deficient (PAI-1-/-) mice after BDL. PAI-1-/- mice had fewer and smaller bile infarcts, less neutrophil infiltration, and higher levels of cholangiocyte and hepatocyte proliferation than WT animals after BDL. Furthermore, PAI-1-/- mice had higher levels of tPA activation and mature hepatocyte growth factor (HGF) after BDL than WT mice, suggesting that PAI-1 effects on HGF activation critically influence cholestatic liver injury. This was further supported by elevated levels of c-Met and Akt phosphorylation in PAI-1-/- mice after BDL. In conclusion, PAI-1 deficiency reduces liver injury after BDL in mice. These data suggest that inhibiting PAI-1 might attenuate liver injury in cholestatic liver diseases.
Project description:Cancer patients often develop hemostasis disorders whose pathogenesis is poorly understood. Previous work in mouse models has shown that these disorders can be sustained by the MET oncogene by transcriptional upregulation of hemostasis genes. Here we investigated the correlation between the procoagulant state of colorectal cancer patients, and overexpression of MET and hemostasis genes in the tumor. We found that, in a patient subset, blood levels of D-dimer and coagulation factor XII (F12) were frequently elevated, and reverted towards normality after surgery. Global expression profiling of tumor tissues and adjacent mucosae revealed a significant correlation between high D-dimer levels in the blood, and overexpression of MET in the tumor. An “hemostasis gene signature”, including F12, cyclo-oxygenase 2, thromboxane synthase-1, plasminogen activator inhibitor-1, urokinase-type plasminogen activator and protein C receptor was associated with MET overexpression. This association was confirmed in an independent 173-sample CRC dataset. The mechanistic link between MET signaling and F12 expression was established experimentally in cell lines. These data indicate that MET contributes to the pathogenesis of coagulation disorders in CRC by upregulation of hemostasis genes including F12, and provide a candidate biomarker for the CRC-associated procoagulant state.
Project description:Recombinant tissue-type plasminogen activator (tPA) is the fibrinolytic drug of choice to treat stroke patients. However, a growing body of evidence indicates that besides its beneficial thrombolytic role, tPA can also have a deleterious effect on the ischaemic brain. Although ageing influences stroke incidence, complications and outcome, age-dependent relationships between endogenous tPA and stroke injuries have not been investigated yet. Here, we report that ageing is associated with a selective lowering of brain tPA expression in the murine brain. Moreover, our results show that albumin D site-binding protein (DBP) as a key age-associated regulator of the neuronal transcription of tPA. Additionally, inhibition of DBP-mediated tPA expression confers in vitro neuroprotection. Accordingly, reduced levels of tPA in old mice are associated with smaller excitotoxic/ischaemic injuries and protection of the permeability of the neurovascular unit during cerebral ischaemia. Likewise, we provide neuroradiological evidence indicating the existence of an inverse relationship between age and the volume of the ischaemic lesion in patients with acute ischaemic stroke. Together, these results indicate that the relationship among DBP, tPA and ageing play an important role in the outcome of cerebral ischaemia. For each stage (4 months and 21 months), samples were prepared by pooling an equal amount of the 3 individual RNA. Five M-BM-5g of total RNA from each pool were reverse-transcribed in the presence of 7.5M-BM-5M random hexamers (GE Healthcare), 75M-BM-5M aminoallyl-dUTP (Sigma-Aldrich) and 100U Rtases Reverse-iT Blend (Thermo scientific) overnight at 37M-BM-0C. Aminoallyl cDNAs were then labelled with Cy5 or Cy3 mono-Reactive Dye (GE Healthcare) according to the manusfacturerM-bM-^@M-^Ys instructions. Labelled cDNAs were then purified on Qiaquick PCR prurification kit (Qiagen) and hybridized to the RNG-MRC_MM25k_EVRY microarrays (Le brigand et al., NAR, 2006) according to the RNG procedures (http://www.microarray.fr:8080/merge/index). Each pool was hybridized in duplicate dye-swap independent experiments. After hybridization, median signal and median background intensities were extracted using Genepix 4.1 software (Axon Instruments). We have first evaluated the level of expression of each gene by calculating the mean ratio M-bM-^@M-^\signal/backgroundM-bM-^@M-^] for each corresponding spot from the 2 dye-swap experiments. Genes were considered to be expressed if their mean ratio was higher or equal to 1.2. Genes with mean ratio < 1.2 in the 2 conditions were not used for further analysis. These filtered data were then submitted to VARAN (http//:www. bionet. espci.fr) for normalization by lowess fit and differential expression analysis (Golfier et al., 2004). Normalized log2ratio 21 months/4 months were then used for further statistical analysis by SAM software (Tusher et al., 2001) and t-test with a p-value equal to 5% using TIGR Multiexperiment Viewer (TM4:MeV, http://www.tm4.org/mev.html). The final list of differentially expressed genes was established by comparing the results obtained with the 3 methods.