Encoding Plasminogen Activator Research Articles

TGF-β1 -Induced Expression of the Anti-Apoptotic PAI-1 Protein Requires EGFR Signaling

TGF-β1 and its target gene encoding plasminogen activator inhibitor-1 (PAI-1) are major regulators of capillary outgrowth, vessel maturation and angiogenic network stability. The increasing realization of the complexity of PAI-1 action in the vascular system requires analysis of specific signaling events that impact its expression in a physiologically-relevant cell system. PAI-1 was required for tubular differentiation and maintenance of cellular survival in complex gels since targeted disruption of PAI-1 synthesis or activity with antisense constructs or function-blocking antibodies resulted in network regression. Indeed, serum-deprivation-induced apoptosis of tubulogenic T2 cells was concentration-dependently inhibited by addition of a stable PAI-1 mutant protein consistent with the established pro-survival role of PAI-1 in vascular endothelial cells. PAI-1 induction and ERK pathway activation in response to TGF-β1 was attenuated by EGFR signaling blockade (with AG1478) or preincubation with the MMP/ADAM inhibitor GM6001. The combination of AG1478 + GM6001 completely ablated both responses suggesting that EGFR transactivation is important in PAI-1 gene control and may, at least partially, involve ligand shedding. TGF-β1-stimulated PAI-1 induction was preceded, in fact, by EGFR phosphorylation on Y845 (a src kinase target residue). EGFR1 knockdown with lentiviral shRNA constructs, moreover, effectively decreased (by >75%) TGF-β1-stimulated PAI-1 expression whereas infection with control (i.e. GFP) viruses had no effect. TGF-β1 failed to induce PAI-1 synthesis in EGFR-deficient fibroblasts while introduction of a wild-type EGFR1 construct in EGFR(-/-) cells rescued the PAI-1 response to TGF-β1 confirming, at a genetic level, the targeted knockdown data. The continued clarification of novel cooperative signaling cascades that impact expression of important angiogenic genes (e.g. PAI-1) may provide therapeutically useful targets to manage the pathophysiology of human neoplastic and vascular diseases.

Plasminogen activator inhibitor variants PAI-1 A15T and PAI-2 S413C influence lung cancer prognosis

The plasminogen pathway plays an important role in the behavior of many tumors including lung cancer. Hence genetic variants encoding plasminogen activator (PLAU), plasminogen receptor (PLAUR), plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2) may contribute to lung cancer prognosis. To investigate this proposition we genotyped PAI-1 A15T, PLAU L141P, PLAUR L317P and PAI-2 S413C variants in 698 patients with lung cancer, 522 with non-small cell (NSCLC) and 176 with small cell lung cancer (SCLC). PAI-1 A15T was significantly associated with overall survival (OS), with carriers of variant alleles having a worse prognosis (hazard ratio (HR) = 1.14; 95% confidence interval [CI]: 1.03–1.26). An association was also detected between OS in NSCLC and carrier status for PAI-2 413C (HR = 1.13; 95% CI: 1.01–1.24). These common genetic variants identified warrant further evaluation as promising prognostic markers of patient outcome.

Transforming Growth Factor-β Requires Its Target Plasminogen Activator Inhibitor-1 for Cytostatic Activity

The cytokine transforming growth factor beta (TGFbeta) has strong antiproliferative activity in most normal cells but contributes to tumor progression in the later stages of oncogenesis. It is not fully understood which TGFbeta target genes are causally involved in mediating its cytostatic activity. We report here that suppression of the TGFbeta target gene encoding plasminogen activator inhibitor-1 (PAI-1) by RNA interference leads to escape from the cytostatic activity of TGFbeta both in human keratinocytes (HaCaTs) and primary mouse embryo fibroblasts. Consistent with this, PAI-1 knock-out mouse embryo fibroblasts are also resistant to TGFbeta growth arrest. Conversely, we show that ectopic expression of PAI-1 in proliferating HaCaT cells induces a growth arrest. PAI-1 knockdown does not interfere with canonical TGFbeta signaling as judged by SMAD phosphorylation and induction of bona fide TGFbeta target genes. Instead, knockdown of PAI-1 results in sustained activation of protein kinase B. Significantly, we find that constitutive protein kinase B activity leads to evasion of the growth-inhibitory action of TGFbeta. Our data are consistent with a model in which induction of PAI-1 by TGFbeta is critical for the induction of proliferation arrest.

Differential Regulation of Matrix Metalloproteinase-9 and Tissue Plasminogen Activator Activity by the Cyclic-AMP System in Lipopolysaccharide-stimulated Rat Primary Astrocytes

We investigated the effect of the cAMP system on lipopolysaccharide (LPS)-induced changes in the activity of matrix metalloproteinases (MMPs) and tissue plasminogen activator (tPA) in rat primary astrocytes. LPS stimulation increased MMP-9 and decreased tPA activity in rat primary astrocytes. Co-treatment with a cAMP analog, dibutyryl-cAMP (db-cAMP), or the cAMP elevating beta-adrenergic agonist, isoproterenol, concentration-dependently inhibited LPS-induced MMP-9 activity. In contrast, db-cAMP concentration-dependently increased tPA activity in both basal and LPS-stimulated rat primary astrocytes. To confirm the effect of cAMP on MMP-9 and tPA activity, we treated LPS-stimulated astrocytes with cAMP phosphodiesterase inhibitors, IBMX or rolipram, and they exhibited similar effects to db-cAMP, namely decreasing MMP-9 activity and increasing tPA activity. RT-PCR analysis of MMP-9 mRNA expression and MMP-9 promoter luciferase reporter assays revealed transcriptional upregulation by LPS stimulation and downregulation by db-cAMP. In contrast, the level of tPA mRNA expression was increased both by LPS and by cAMP treatment. Consistent with RT-PCR analysis, tPA promoter reporter assays showed increased activity by both LPS and cAMP stimulation. Interestingly, the level of mRNA encoding plasminogen activator inhibitor-1 (PAI-1) was increased by LPS stimulation and decreased back to control level after co-treatment with db-cAMP, suggesting that PAI-1 expression plays a major role in the regulation of tPA activity. To examine PKA involvement in the effects of db-cAMP on MMP-9 and tPA activity, we added the PKA inhibitors, H89 or rp-cAMP, along with db-cAMP, and they inhibited db-cAMP-mediated changes in tPA activity without affecting MMP-9 activity. These data suggest that cAMP differentially modulates MMP-9 and tPA activity through a mechanism related to PKA activation. The differential regulation of MMP-9 and tPA by the cAMP system may confer more sophisticated regulation of physiological processes, such as extracellular matrix remodeling and cell migration, by activated astrocytes.

SERPINE1 (PAI-1) is deposited into keratinocyte migration “trails” and required for optimal monolayer wound repair

Cutaneous tissue injury, both in vivo and in vitro, initiates activation of a "wound repair" transcriptional program. One such highly induced gene encodes plasminogen activator inhibitor type-1 (PAI-1, SERPINE1). PAI-1-GFP, expressed as a fusion protein under inducible control of +800 bp of the wound-activated PAI-1 promoter, prominently "marked" keratinocyte migration trails during the real-time of monolayer scrape-injury repair. Addition of active recombinant PAI-1 to wounded wild-type keratinocyte monolayers as well as to PAI-1(-/-) MEFs and PAI-1(-/-) keratinocytes significantly stimulated directional motility above basal levels in all cell types. PAI-1 expression knockdown or antibody-mediated functional inhibition, in contrast, effectively attenuated injury repair. The defect in wound-associated migratory activity as a consequence of antisense-mediated PAI-1 down-regulation was effectively reversed by addition of recombinant PAI-1 immediately after scrape injury. One possible mechanism underlying the PAI-1-dependent motile response may involve fine control of the keratinocyte substrate detachment/re-attachment process. Exogenous PAI-1 significantly enhanced keratinocyte spread cell "footprint" area while PAI-1 neutralizing antibodies, but not control non-immune IgG, effectively inhibited spreading with apoptotic hallmarks evident within 24 h. Importantly, PAI-1 not only stimulated keratinocyte adhesion and wound-initiated planar migration but also rescued keratinocytes from plasminogen-induced substrate detachment/anoikis. The early transcriptional response of the PAI-1 gene to monolayer trauma and its prominence in the injury repair genetic signature are consistent with its function as both a survival factor and regulator of the time course of epithelial migration as part of the cutaneous injury response program.

TGF-β1-induced plasminogen activator inhibitor-1 expression in vascular smooth muscle cells requires pp60c-src/EGFRY845 and Rho/ROCK signaling

TGF-β1 and its target gene encoding plasminogen activator inhibitor-1 (PAI-1) are major causative factors in the pathology of tissue fibrosis and vascular disease. The increasing complexity of TGF-β1 action in the cardiovascular system requires analysis of specific TGF-β1-initiated signaling events that impact PAI-1 transcriptional regulation in a physiologically-relevant cell system. TGF-β1-induced PAI-1 expression in both primary cultures and in an established line (R22) of vascular smooth muscle cells (VSMC) was completely blocked by inhibition of epidermal growth factor receptor (EGFR) activity or adenoviral delivery of a kinase-dead EGFRK721A construct. TGF-β1-stimulated PAI-1 expression, moreover, was preceded by EGFR phosphorylation on Y845 (a src kinase target residue) and required pp60c-src activity. Infection of VSMC with an adenovirus encoding the EGFRY845F mutant or transfection with a dominant-negative pp60c-src (DN-Src) expression vector effectively decreased TGF-β1-stimulated, but not PDGF-induced, PAI-1 expression implicating the pp60c-src phosphorylation site EGFRY845 in the inductive response. Consistent with these findings, TGF-β1 failed to induce PAI-1 synthesis in src kinase-deficient (SYF−/−/−) fibroblasts and reexpression of a wild-type pp60c-src construct in SYF−/−/− cells rescued the PAI-1 response to TGF-β1. TGF-β1-induced EGFR activation, but not SMAD2 activation, moreover, was virtually undetectable in SYK−/−/− fibroblasts in comparison to wild type (SYK+/+/+) counterparts, confirming an upstream signaling role of src family kinases in EGFRY845 phosphorylation. Genetic EGFR deficiency or infection of VSMCs with EGFRK721A virtually ablated TGF-β1-stimulated ERK1/2 activation as well as PAI-1 expression but not SMAD2 phosphorylation. Transient transfection of a dominant-negative RhoA (DN-RhoA) expression construct or pretreatment of VSMC with C3 transferase (a Rho inhibitor) or Y-27632 (an inhibitor of p160ROCK, a downstream effector of Rho) also dramatically attenuated the TGF-β1-initiated PAI-1 inductive response. In contrast to EGFR pathway blockade, interference with Rho/ROCK signaling effectively inhibited TGF-βR-mediated SMAD2 phosphorylation and nuclear accumulation. TGF-β1-stimulated SMAD2 activation, moreover, was not sufficient to induce PAI-1 expression in the absence of EGFR signaling both in VSMC and mouse embryonic fibroblasts. Thus, two distinct pathways involving the EGFR/pp60c-src/MEK-ERK pathway and Rho/ROCK-dependent SMAD2 activation are required for TGF-β1-induced PAI-1 expression in VSMC. The identification of such novel interactions between two TGF-β1-activated signaling networks that specifically impact PAI-1 transcription in VSMC may provide therapeutically-relevant targets to manage the pathophysiology of PAI-1-associated cardiovascular/fibrotic diseases.

Plasminogen activator inhibitor-1 is a critical downstream target of p53 in the induction of replicative senescence

p53 limits the proliferation of primary diploid fibroblasts by inducing a state of growth arrest named replicative senescence - a process which protects against oncogenic transformation and requires integrity of the p53 tumour suppressor pathway. However, little is known about the downstream target genes of p53 in this growth-limiting response. Here, we report that suppression of the p53 target gene encoding plasminogen activator inhibitor-1 (PAI-1) by RNA interference (RNAi) leads to escape from replicative senescence both in primary mouse embryo fibroblasts and primary human BJ fibroblasts. PAI-1 knockdown results in sustained activation of the PI(3)K-PKB-GSK3beta pathway and nuclear retention of cyclin D1, consistent with a role for PAI-1 in regulating growth factor signalling. In agreement with this, we find that the PI(3)K-PKB-GSK3beta-cyclin D1 pathway is also causally involved in cellular senescence. Conversely, ectopic expression of PAI-1 in proliferating p53-deficient murine or human fibroblasts induces a phenotype displaying all the hallmarks of replicative senescence. Our data indicate that PAI-1 is not merely a marker of senescence, but is both necessary and sufficient for the induction of replicative senescence downstream of p53.

Myofibroblast progenitor cells are increased in number in patients with type 1 diabetes and express less bone morphogenetic protein 6: a novel clue to adverse tissue remodelling?

Growth factor imbalance and endothelial progenitor cell dysfunction are well-known elements of the inappropriate response to injury in human and experimental diabetes. We hypothesised that in diabetes the outgrowth of myofibroblast progenitor cells (MFPCs) is also altered and that this relates to aberrant gene expression of growth factors involving members of the TGF-beta/bone morphogenetic protein (BMP) superfamily. MFPCs were cultured from peripheral blood mononuclear cells of patients with type 1 diabetes and control subjects. Microarray analysis, quantitative PCR and ELISA were used to identify differentially regulated TGF-beta/BMP superfamily genes in diabetes- and control-derived MFPC. Possible effects of BMP6 on TGF-beta-induced gene expression were examined in cultured renal fibroblasts (TK173 cells). Blood from diabetic patients yielded higher numbers of MFPCs than blood from control subjects (1.6-fold increase, p<0.05), involving increased proliferation and decreased apoptosis. BMP6 mRNA and protein were downregulated in MFPCs derived from patients with diabetes (3.9- and 1.8-fold decrease, respectively, p<0.05). Furthermore, an inverse correlation was observed between BMP6 mRNA level and the number of MFPCs in patients with diabetes (r=-0.85, p<0.05). In TK173 cells, BMP6 antagonised the TGF-beta-induced expression of the genes encoding plasminogen activator inhibitor-1 and connective tissue growth factor (70 and 50% reduction, respectively). Considering the importance of BMP6 in processes such as angiogenesis and its novel anti-TGF-beta effects, we propose that the excess numbers of BMP6-deficient MFPCs may favour adverse tissue remodelling in patients with diabetes, both numerically and by inappropriate orchestration of their microenvironment.

Transcriptional Profiling After Bile Duct Ligation Identifies PAI-1 as a Contributor to Cholestatic Injury in Mice *

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.

Nucleotide variations in genes encoding plasminogen activator inhibitor-2 and serine proteinase inhibitor B10 associated with prostate cancer

Genes encoding the serine proteinase inhibitor B family (SERPINBs) are mainly clustered on human chromosome 18 (18q21). Several serpins are known to affect malignant phenotypes of tumor cells, so aberrant genetic variants in this molecular family are candidates for conferring susceptibility for risk of cancer. We investigated whether eight selected non-synonymous variations within SERPINB loci at 18q21 might be associated with risk of prostate cancer in Japanese men. A case-control study involving 292 prostate-cancer patients and 384 controls revealed significant differences in regard to distribution of four missense variations in genes encoding plasminogen activator inhibitor 2 (PAI2) and SERPINB10. The most significant association was detected for the N120D polymorphism in the PAI2 gene (P = 5.0 x 10(-5)); men carrying the 120-N allele (120-N/N and 120-N/D genotypes) carried a 2.4-fold increased risk of prostate cancer (95% confidence interval 1.45-4.07). Associations were also detected for three other missense polymorphisms in those two genes. Strong linkage disequilibrium in the region encompassing PAI2 and SERPINB10 extended to about 50 kbp. The results suggested that missense variations in one or both of these genes confer important risks for prostate cancer, and may be themselves tumorigenic. Although confirmative replication studies on larger cohorts are awaited, clinical examination of these variations may become useful for identifying individuals at high risk for prostate cancer.

Testosterone Suppresses Protective Responses of the Liver to Blood-Stage Malaria

Testosterone induces a lethal outcome in otherwise self-healing blood-stage malaria caused by Plasmodium chabaudi. Here, we examine possible testosterone effects on the antimalaria effectors spleen and liver in female C57BL/6 mice. Self-healing malaria activates gating mechanisms in the spleen and liver that lead to a dramatic reduction in trapping activity, as measured by quantifying the uptake of 3-mum-diameter fluorescent polystyrol particles. However, testosterone delays malaria-induced closing of the liver, but not the spleen. Coincidently, testosterone causes an approximately 3- to 28-fold depression of the mRNA levels of nine malaria-responsive genes, out of 299 genes tested, only in the liver and not in the spleen, as shown by cDNA arrays and Northern blotting. Among these are the genes encoding plasminogen activator inhibitor (PAI1) and hydroxysteroid sulfotransferase (STA2). STA2, which detoxifies bile acids, is suppressed 10-fold by malaria and an additional 28-fold by testosterone, suggesting a severe perturbation of bile acid metabolism. PAI1 is protective against malaria, since disruption of the PAI1 gene results in partial loss of the ability to control the course of P. chabaudi infections. Collectively, our data indicate that the liver rather than the spleen is a major target organ for testosterone-mediated suppression of resistance against blood-stage malaria.

Plasminogen Activator Inhibitor-1 Polymorphism in Women with Pre-eclampsia

We determined whether or not genetic variability in the promoter region of the gene encoding plasminogen activator inhibitor-1 (PAI1) contributes to individual differences in susceptibility to the development of preeclampsia. The study involved 133 preeclamptic and 115 healthy control pregnant women who were genotyped for a single-nucleotide insertion/deletion polymorphism (4G/5G) at position -675 in the PAI1 gene promoter. Furthermore, the frequencies of the alleles in the general middle-aged population are presented for comparison. Chi-square analysis was used to assess genotype and allele frequency differences between preeclamptic women and controls. A similar allelic distribution of PAI1 4G/5G polymorphism was observed in the two groups, with the frequency of the variant 4G allele being 50.4% in the preeclampsia group and 54.3% in the control group (p = 0.377; OR = 0.85, 95% CI = 0.60-1.22). Accordingly, the genotype distribution of the PAI1 4G/5G polymorphism in the preeclamptic and control groups was found to be similar (p = 0.68). Overall, this genotype data on fertile women is almost identical to that in the general middle-aged Finnish population. The 4G/5G polymorphism of the PAI1 gene promoter is unlikely to be a major genetic predisposing factor as regards preeclampsia in subjects from eastern Finland. These results are not suggestive of an important contribution of the PAI1 genotype on preeclampsia across populations.

Genetic Disruption of Cortical Interneuron Development Causes Region- and GABA Cell Type-Specific Deficits, Epilepsy, and Behavioral Dysfunction

The generation of properly functioning circuits during brain development requires precise timing of cell migration and differentiation. Disruptions in the developmental plan may lead to neurological and psychiatric disorders. Neocortical circuits rely on inhibitory GABAergic interneurons, the majority of which migrate from subcortical sources. We have shown that the pleiotropic molecule hepatocyte growth factor/scatter factor (HGF/SF) mediates interneuron migration. Mice with a targeted mutation of the gene encoding urokinase plasminogen activator receptor (uPAR), a key component in HGF/SF activation and function, have decreased levels of HGF/SF and a 50% reduction in neocortical GABAergic interneurons at embryonic and perinatal ages. Disruption of interneuron development leads to early lethality in most models. Thus, the long-term consequences of such perturbations are unknown. Mice of the uPAR-/- strain survive until adulthood, and behavior testing demonstrates that they have an increased anxiety state. The uPAR-/- strain also exhibits spontaneous seizure activity and higher susceptibility to pharmacologically induced convulsions. The neocortex of the adult uPAR-/- mouse exhibits a dramatic region- and subtype-specific decrease in GABA-immunoreactive interneurons. Anterior cingulate and parietal cortical areas contain 50% fewer GABAergic interneurons compared with wild-type littermates. However, interneuron numbers in piriform and visual cortical areas do not differ from those of normal mice. Characterization of interneuron subpopulations reveals a near complete loss of the parvalbumin subtype, with other subclasses remaining intact. These data demonstrate that a single gene mutation can selectively alter the development of cortical interneurons in a region- and cell subtype-specific manner, with deficits leading to long-lasting changes in circuit organization and behavior.

Epithelial monolayer wounding stimulates binding of USF-1 to an E-box motif in the plasminogen activator inhibitor type 1 gene.

Several proteases and their co-expressed inhibitors modulate the interdependent processes of cell migration and matrix proteolysis during wound repair. Transcription of the gene encoding plasminogen activator inhibitor type 1 (PAI-1), a serine protease inhibitor important in the control of barrier proteolysis and cell-to-matrix adhesion, is spatially-temporally regulated following epithelial denudation injury in vitro as well as in vivo. Using a well-defined culture model of acute epidermal wounding and reepithelialization, PAI-1 mRNA/protein synthesis was induced early after monolayer scraping and restricted to cells comprising the motile cohort. PAI-1 levels in locomoting cells remained elevated (relative to the distal, contact-inhibited monolayer regions) throughout the time course of trauma repair. Targeted PAI-1 downregulation by transfection of antisense PAI-1 expression constructs significantly impaired keratinocyte migration and monolayer scrape wound closure. Injury-induced PAI-1 transcription closely paralleled growth state-dependent controls on the PAI-1 gene. An E-box motif (CACGTG) in the PAI-1 proximal promoter (located at nucleotides -160 to -165), previously shown to be necessary for serum-induced PAI-1 expression, was bound by nuclear factors from wound-stimulated but not quiescent, contact-inhibited, keratinocytes. UV crosslinking approaches to identify E-box-binding factors coupled with deoxyoligonucleotide affinity chromatography and gel retardation assays confirmed at least one major E-box-binding protein in both serum- and wound-activated cells to be USF-1, a member of the helix-loop-helix family of transcription factors. An intact hexanucleotide E-box motif was necessary and sufficient for USF-1 binding using nuclear extracts from both serum- and wound-simulated cells. Two species of immunoreactive USF-1 were identified by western blotting of total cellular lysates that corresponded to the previously characterized phosphorylated and non-phosphorylated forms of the protein. USF-1 isolated by PAI-1 promoter-DNA affinity chromatography was almost exclusively phosphorylated. Only a fraction of the total cellular USF-1 in proliferating cultures, by comparison, was phosphorylated at any given time. PAI-1 E-box binding activity, assessed by probe mobility shift criteria, increased within 2 hours of monolayer scrape injury, a time frame consistent with wound-stimulated increases in PAI-1 transcription. Relative to intact cultures, scrape site-juxtaposed cells had significantly greater cytoplasmic and nuclear USF-1 immunoreactivity correlating with the specific in situ-restricted expression of PAI-1 transcripts/protein in the wound-edge cohort. USF-1 immunocytochemical staining declined significantly with increasing distance from the denudation site. These data are the first to indicate that binding of USF-1 to its target motif can be induced by 'tissue' injury in vitro and implicate USF-1 as a transcriptional regulator of genes (e.g. PAI-1) involved in wound repair.

Paradoxical rescue from ischemic lung injury by inhaled carbon monoxide driven by derepression of fibrinolysis.

Carbon monoxide (CO) can arrest cellular respiration, but paradoxically, it is synthesized endogenously by heme oxygenase type 1 (Ho-1) in response to ischemic stress. Ho-1-deficient (Hmox1-/-) mice exhibited lethal ischemic lung injury, but were rescued from death by inhaled CO. CO drove ischemic protection by activating soluble guanylate cyclase and thereby suppressed hypoxic induction of the gene encoding plasminogen activator inhibitor-1 (PAI-1) in mononuclear phagocytes, which reduced accrual of microvascular fibrin. CO-mediated ischemic protection observed in wild-type mice was lost in mice null for the gene encoding PAI-1 (Serpine1). These data establish a fundamental link between CO and prevention of ischemic injury based on the ability of CO to derepress the fibrinolytic axis. These data also point to a potential therapeutic use for inhaled CO.

Comprehensive gene expression profile of LPS-stimulated human monocytes by SAGE

Monocytes play a pivotal role in various human infectious and inflammatory diseases. To reveal a whole picture of pathophysiologic function of activated human monocytes, this study used the serial analysis of gene expression (SAGE) procedure in lipopolysaccharide (LPS)-stimulated human monocytes. A total of 35 874 tags corresponding to more than 12 000 different transcripts were sequenced. Comparison of gene expression profile with that of resting monocytes revealed the LPS-inducible gene expression profile. Many cytokines and chemokines, including interleukin (IL)-6, IL-1α, IL-1β, tumor necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-1β, MIP-2β, MIP-2α, liver and activation-regulated chemokine (LARC), MIP-1α, thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), regulated on activation, normal T cell expressed and secreted (RANTES), growth-regulated oncogene (GRO) α, and IL-8, were observed in the highest inducible transcripts. Other genes encoding plasminogen activator inhibitor type 2 (PAI-2), Hc-gp39, apolipoproteins, malate dehydrogenase, matrix metalloproteinase-9 (MMP-9), and cyclooxygenase (COX2) were also highly elevated in LPS-stimulated monocytes. Moreover, up-regulation of Naf1β, IL-7 receptor, adenosine receptor A2a, and many novel genes was newly identified. These results suggest that the LPS-inducible gene products may be involved in cell activation and migration, angiogenesis, tissue remodeling, and metabolism, and thus may orchestrate the inflammatory reactions. On the other hand, the expression of numerous sets of novel genes was discovered to be down-regulated on LPS stimulation. This study represents the first comprehensive analysis of LPS-inducible gene expression in human monocytes and provides tremendous novel information for the function of LPS-activated monocytes and targets for diagnosing, monitoring, and treating sepsis and various human infectious and inflammatory diseases.

Comprehensive gene expression profile of LPS-stimulated human monocytes by SAGE

AbstractMonocytes play a pivotal role in various human infectious and inflammatory diseases. To reveal a whole picture of pathophysiologic function of activated human monocytes, this study used the serial analysis of gene expression (SAGE) procedure in lipopolysaccharide (LPS)-stimulated human monocytes. A total of 35 874 tags corresponding to more than 12 000 different transcripts were sequenced. Comparison of gene expression profile with that of resting monocytes revealed the LPS-inducible gene expression profile. Many cytokines and chemokines, including interleukin (IL)-6, IL-1α, IL-1β, tumor necrosis factor (TNF)-α, macrophage inflammatory protein (MIP)-1β, MIP-2β, MIP-2α, liver and activation-regulated chemokine (LARC), MIP-1α, thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), regulated on activation, normal T cell expressed and secreted (RANTES), growth-regulated oncogene (GRO) α, and IL-8, were observed in the highest inducible transcripts. Other genes encoding plasminogen activator inhibitor type 2 (PAI-2), Hc-gp39, apolipoproteins, malate dehydrogenase, matrix metalloproteinase-9 (MMP-9), and cyclooxygenase (COX2) were also highly elevated in LPS-stimulated monocytes. Moreover, up-regulation of Naf1β, IL-7 receptor, adenosine receptor A2a, and many novel genes was newly identified. These results suggest that the LPS-inducible gene products may be involved in cell activation and migration, angiogenesis, tissue remodeling, and metabolism, and thus may orchestrate the inflammatory reactions. On the other hand, the expression of numerous sets of novel genes was discovered to be down-regulated on LPS stimulation. This study represents the first comprehensive analysis of LPS-inducible gene expression in human monocytes and provides tremendous novel information for the function of LPS-activated monocytes and targets for diagnosing, monitoring, and treating sepsis and various human infectious and inflammatory diseases.

Expression of the plague plasminogen activator in Yersinia pseudotuberculosis and Escherichia coli.

Enteropathogenic yersiniae (Yersinia pseudotuberculosis and Yersinia enterocolitica) typically cause chronic disease as opposed to the closely related Yersinia pestis, the causative agent of bubonic plague. It is established that this difference reflects, in part, carriage by Y. pestis of a unique 9.6-kb pesticin or Pst plasmid (pPCP) encoding plasminogen activator (Pla) rather than distinctions between shared approximately 70-kb low-calcium-response, or Lcr, plasmids (pCD in Y. pestis and pYV in enteropathogenic yersiniae) encoding cytotoxic Yops and anti-inflammatory V antigen. Pla is known to exist as a combination of 32.6-kDa (alpha-Pla) and slightly smaller (beta-Pla) outer membrane proteins, of which at least one promotes bacterial dissemination in vivo and degradation of Yops in vitro. We show here that only alpha-Pla accumulates in Escherichia coli LE392/pPCP1 cultivated in enriched medium and that either autolysis or extraction of this isolate with 1.0 M NaCl results in release of soluble alpha and beta forms possessing biological activity. This process also converted cell-bound alpha-Pla to beta-Pla and smaller forms in Y. pestis KIM/pPCP1 and Y. pseudotuberculosis PB1/+/pPCP1 but did not promote solubilization. Pla-mediated posttranslational hydrolysis of pulse-labeled Yops in Y. pseudotuberculosis PB1/+/pPCP1 occurred more slowly than that in Y. pestis but was otherwise similar except for accumulation of stable degradation products of YadA, a pYV-mediated fibrillar adhesin not encoded in frame by pCD. Carriage of pPCP by Y. pseudotuberculosis did not significantly influence virulence in mice.

Calcium oxalate monohydrate crystals stimulate gene expression in renal epithelial cells

Primary or secondary hyperoxaluria is associated with calcium oxalate nephrolithiasis, interstitial fibrosis and progressive renal insufficiency. Monolayer cultures of nontransformed monkey kidney epithelial cells (BSC-1 line) and calcium oxalate monohydrate (COM) crystals were used as a model system to study cell responses to crystal interactions that might occur in the nephrons of patients during periods of hyperoxaluria. To determine if COM crystals signal a change in gene expression, Northern blots were prepared from total renal cellular RNA after the cells were exposed to crystals. The immediate early genes c-myc, EGR-1, and Nur-77 were induced at one hour. At two to six hours stimulated expression of the genes encoding plasminogen activator inhibitor (PAI-1) and platelet-derived growth factor (PDGF)-A chain was detected, but constitutive expression of urokinase-type plasminogen activator (u-PA) was not altered. Expression of connective tissue growth factor (CTGF) was induced at one hour and persisted up to 24 hours. The stimulation of gene expression by COM crystals was relatively crystal- and renal cell-type specific. Thus the interaction of kidney epithelial cells with COM crystals alters expression of genes that encode three classes of proteins: transcriptional activators, a regulator of extracellular matrix (ECM), and growth factors. Activation of PAI-1 gene expression without a change in u-PA favors accumulation of ECM proteins, as does increased expression of PDGF and CTGF which can also stimulate fibroblast proliferation in a paracrine manner. These results suggest that COM crystal-mediated stimulation of specific genes in renal tubular cells may contribute to the development of interstitial fibrosis in hyperoxaluric states.

Southwestern blot mapping of potential regulatory proteins binding to the DNA encoding plasminogen activator inhibitor type 2

In order to investigate the molecular basis for the regulated expression of plasminogen activator inhibitor type 2 (PAI-2), we sought to identify monocyte-derived nuclear factors which interact with the PAI-2 gene. We have explored the application of Southwestern blot mapping as an approach for identifying specific DNA-protein interactions and targeting potential regulatory DNA elements. The procedure involves an initial global screening of a crude preparation of nuclear proteins with radiolabelled DNA fragments (200–300 bp) derived from a large region (8.8 kb) of PAI-2. The bound DNA fragments are eluted and their location within PAI-2 mapped by Southern blot hybridization analysis. We have used this procedure to examine the differential binding of nuclear factors from the U937 monocytic cell in the absence and in the presence of the differentiating agent, 12-phorbol 13-myristate acetate (PMA), in order to identify proteins that bind specifically to the 5' flanking promoter region and first intron of PAI-2. Eleven DNA-binding proteins ranging in molecular mass from 27 to 92 kDa were identified, and the results define three regions of the gene which contain DNA-binding sites which may be involved in the transcriptional regulation of PAI-2. Deletion analysis using a series of 5' deletion mutants spanning PAI-2 fused to a chloramphenicol acetyltransferase-encoding reporter gene ( cat) demonstrates that two of the regions identified by Southwestern blot mapping contain elements which can function to modulate PAI-2 expression in transient transfections of U937 cells.