RESUMEN
The Drosophila defense against pathogens largely relies on the activation of two signaling pathways: immune deficiency (IMD) and Toll. The IMD pathway is triggered mainly by Gram-negative bacteria, whereas the Toll pathway responds predominantly to Gram-positive bacteria and fungi. The activation of these pathways leads to the rapid induction of numerous NF-κB-induced immune response genes, including antimicrobial peptide genes. The IMD pathway shows significant similarities with the TNF receptor pathway. Recent evidence indicates that the IMD pathway is also activated in response to various noninfectious stimuli (i.e., inflammatory-like reactions). To gain a better understanding of the molecular machinery underlying the pleiotropic functions of this pathway, we first performed a comprehensive proteomics analysis to identify the proteins interacting with the 11 canonical members of the pathway initially identified by genetic studies. We identified 369 interacting proteins (corresponding to 291 genes) in heat-killed Escherichia coli-stimulated Drosophila S2 cells, 92% of which have human orthologs. A comparative analysis of gene ontology from fly or human gene annotation databases points to four significant common categories: (i) the NuA4, nucleosome acetyltransferase of H4, histone acetyltransferase complex, (ii) the switching defective/sucrose nonfermenting-type chromatin remodeling complex, (iii) transcription coactivator activity, and (iv) translation factor activity. Here we demonstrate that sumoylation of the IκB kinase homolog immune response-deficient 5 plays an important role in the induction of antimicrobial peptide genes through a highly conserved sumoylation consensus site during bacterial challenge. Taken together, the proteomics data presented here provide a unique avenue for a comparative functional analysis of proteins involved in innate immune reactions in flies and mammals.
Asunto(s)
Proteínas de Drosophila/inmunología , Drosophila/inmunología , Drosophila/microbiología , Transducción de Señal/inmunología , Secuencia de Aminoácidos , Animales , Animales Modificados Genéticamente , Ensamble y Desensamble de Cromatina/genética , Ensamble y Desensamble de Cromatina/inmunología , Drosophila/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Escherichia coli/inmunología , Genes de Insecto , Histona Acetiltransferasas/genética , Histona Acetiltransferasas/inmunología , Histona Acetiltransferasas/metabolismo , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Mapas de Interacción de Proteínas , Homología de Secuencia de AminoácidoRESUMEN
Background Marinobufagenin, NKA (Na/K-ATPase) inhibitor, causes vasoconstriction and induces fibrosis via inhibition of Fli1 (Friend leukemia integration-1), a negative regulator of collagen synthesis. In vascular smooth muscle cells (VSMC), ANP (atrial natriuretic peptide), via a cGMP/PKG1 (protein kinase G1)-dependent mechanism, reduces NKA sensitivity to marinobufagenin. We hypothesized that VSMC from old rats, due to downregulation of ANP/cGMP/PKG-dependent signaling, would exhibit heightened sensitivity to the profibrotic effect of marinobufagenin. Methods and Results Cultured VSMC from the young (3-month-old) and old (24-month-old) male Sprague-Dawley rats and young VSMC with silenced PKG1 gene were treated with 1 nmol/L ANP, or with 1 nmol/L marinobufagenin, or with a combination of ANP and marinobufagenin. Collagen-1, Fli1, and PKG1 levels were assessed by Western blotting analyses. Vascular PKG1 and Fli1 levels in the old rats were reduced compared with their young counterparts. ANP prevented inhibition of vascular NKA by marinobufagenin in young VSMC but not in old VSMC. In VSMC from the young rats, marinobufagenin induced downregulation of Fli1 and an increase in collagen-1 level, whereas ANP blocked this effect. Silencing of the PKG1 gene in young VSMC resulted in a reduction in levels of PKG1 and Fli1; marinobufagenin additionally reduced Fli1 and increased collagen-1 level, and ANP failed to oppose these marinobufagenin effects, similar to VSMC from the old rats with the age-associated reduction in PKG1. Conclusions Age-associated reduction in vascular PKG1 and the resultant decline in cGMP signaling lead to the loss of the ability of ANP to oppose marinobufagenin-induced inhibition of NKA and fibrosis development. Silencing of the PKG1 gene mimicked these effects of aging.
Asunto(s)
Glicósidos Cardíacos , Hipertensión , Músculo Liso Vascular , Animales , Masculino , Ratas , Envejecimiento/genética , Factor Natriurético Atrial , Células Cultivadas , Colágeno Tipo I , GMP Cíclico , Fibrosis , Ratas Sprague-Dawley , Cloruro de Sodio DietéticoRESUMEN
The gasotransmitter hydrogen sulfide (H2S) is an important biological mediator, playing an essential role in many physiological and pathological processes. It is produced by transsulfuration - an evolutionarily highly conserved pathway for the metabolism of sulfur-containing amino acids methionine and cysteine. Cystathionine-ß-synthase (CBS) and cystathionine-γ-lyase (CSE) enzymes play a central role in cysteine metabolism and H2S production. Here we investigated the fitness components (longevity, stress resistance, viability of preimaginal stages, and reproductive function parameters) in D. melanogaster lines containing deletions of the CBS and CSE genes. Surprisingly, in most tests, CSE deletion improved, and CBS worsened the fitness. Lines with deletion of both CBS and CSE demonstrated better stress resistance and longevity than lines with single CBS deletion. At the same time, deletion of both CBS and CSE genes causes more serious disturbances of reproductive function parameters than single CBS deletion. Thus, a complex interaction of H2S-producing pathways and cellular stress response in determining the lifespan and fitness components of the whole organism was revealed.
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Cistationina gamma-Liasa , Sulfuro de Hidrógeno , Animales , Cistationina , Cistationina betasintasa/genética , Cistationina betasintasa/metabolismo , Cistationina gamma-Liasa/genética , Cistationina gamma-Liasa/metabolismo , Cisteína , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Sulfuro de Hidrógeno/metabolismo , LongevidadRESUMEN
Background Elevated levels of an endogenous Na/K-ATPase inhibitor marinobufagenin accompany salt-sensitive hypertension and are implicated in cardiac fibrosis. Immunoneutralization of marinobufagenin reduces blood pressure in Dahl salt-sensitive (Dahl-S) rats. The effect of the anti-marinobufagenin monoclonal antibody on blood pressure, left ventricular (LV) and renal remodeling, and gene expression were investigated in hypertensive Dahl-S rats. Methods and Results Dahl-S rats were fed high NaCl (8%, HS; n=14) or low NaCl (0.1%, LS; n=14) diets for 8 weeks. Animals were administered control antibody (LS control antibody, LSC; HS control antibody, HSC; n=7 per group) or anti-marinobufagenin antibody once on week 7 of diet intervention (n=7 per group). Levels of marinobufagenin, LV, and kidney mRNAs and proteins implicated in profibrotic signaling were assessed. Systolic blood pressure was elevated (211±8 versus 133±3 mm Hg, P<0.01), marinobufagenin increased 2-fold in plasma (P<0.05) and 5-fold in urine (P<0.01), LV and kidney weights increased, and levels of LV collagen-1 rose 3.5-fold in HSC versus LSC. Anti-marinobufagenin antibody treatment decreased systolic blood pressure by 24 mm Hg (P<0.01) and reduced organ weights and level of LV collagen-1 (P<0.01) in hypertensive Dahl salt-sensitive rats with anti-marinobufagenin antibody versus HSC. The expression of genes related to transforming growth factor-ß-dependent signaling was upregulated in the left ventricles and kidneys in HSC versus LSC groups and became downregulated following administration of anti-marinobufagenin antibody to hypertensive Dahl-S rats. Marinobufagenin also activated transforming growth factor-ß signaling in cultured ventricular myocytes from Dahl-S rats. Conclusions Immunoneutralization of heightened marinobufagenin levels in hypertensive Dahl-S rats resulted in a downregulation of genes implicated in transforming growth factor-ß pathway, which indicates that marinobufagenin is an activator of profibrotic transforming growth factor-ß-dependent signaling in salt-sensitive hypertension.
Asunto(s)
Bufanólidos/farmacología , Regulación de la Expresión Génica , Ventrículos Cardíacos/metabolismo , Hipertensión/genética , Factor de Crecimiento Transformador beta/genética , Remodelación Ventricular/fisiología , Animales , Presión Sanguínea/efectos de los fármacos , Western Blotting , Modelos Animales de Enfermedad , Ecocardiografía , Inhibidores Enzimáticos/farmacología , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/fisiopatología , Hipertensión/tratamiento farmacológico , Hipertensión/fisiopatología , Masculino , ARN/genética , Ratas , Ratas Endogámicas Dahl , Factor de Crecimiento Transformador beta/biosíntesisRESUMEN
Heat-shock genes have numerous features that ought to predispose them to insertional mutagenesis via transposition. To elucidate the evolvability of heat-shock genes via transposition, we have exploited a local transposition technique and Drosophila melanogaster strains with EPgy2 insertions near the Hsp70 gene cluster at 87A7 to produce numerous novel EPgy2 insertions into these Hsp70 genes. More than 50% of 45 independent insertions were made into two adjacent nucleotides in the proximal promoter at positions -96 and -97, and no insertions were into a coding or 3'-flanking sequence. All inserted transposons were in inverse orientation to the starting transposon. The frequent insertion into nucleotides -96 and -97 is consistent with the DNase hypersensitivity, absence of nucleosomes, flanking GAGA-factor-binding sites, and nucleotide sequence of this region. These experimental insertions recapitulated many of the phenotypes of natural transposition into Hsp70: reduced mRNA expression, less Hsp70 protein, and decreased inducible thermotolerance. The results suggest that the distinctive features of heat-shock promoters, which underlie the massive and rapid expression of heat-shock genes upon heat shock, also are a source of evolutionary variation on which natural selection can act.
Asunto(s)
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Genes de Insecto , Proteínas HSP70 de Choque Térmico/genética , Regiones Promotoras Genéticas , Animales , Secuencia de Bases , Cartilla de ADN/genética , Elementos Transponibles de ADN/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Femenino , Expresión Génica , Proteínas HSP70 de Choque Térmico/metabolismo , Masculino , Datos de Secuencia Molecular , Mutagénesis Insercional , Fenotipo , ARN Mensajero/genética , ARN Mensajero/metabolismoRESUMEN
BACKGROUND: Experimental uremic cardiomyopathy causes cardiac fibrosis and is causally related to the increased circulating levels of the cardiotonic steroid, marinobufagenin (MBG), which signals through Na/K-ATPase. Rapamycin is an inhibitor of the serine/threonine kinase mammalian target of rapamycin (mTOR) implicated in the progression of many different forms of renal disease. Given that Na/K-ATPase signaling is known to stimulate the mTOR system, we speculated that the ameliorative effects of rapamycin might influence this pathway. METHODS AND RESULTS: Biosynthesis of MBG by cultured human JEG-3 cells is initiated by CYP27A1, which is also a target for rapamycin. It was demonstrated that 1 µmol/L of rapamycin inhibited production of MBG in human JEG-2 cells. Male Sprague-Dawley rats were subjected to either partial nephrectomy (PNx), infusion of MBG, and/or infusion of rapamycin through osmotic minipumps. PNx animals showed marked increase in plasma MBG levels (1025±60 vs 377±53 pmol/L; P<0.01), systolic blood pressure (169±1 vs 111±1 mm Hg; P<0.01), and cardiac fibrosis compared to controls. Plasma MBG levels were significantly decreased in PNx-rapamycin animals compared to PNx (373±46 vs 1025±60 pmol/L; P<0.01), and cardiac fibrosis was substantially attenuated by rapamycin treatment. CONCLUSIONS: Rapamycin treatment in combination with MBG infusion significantly attenuated cardiac fibrosis. Our results suggest that rapamycin may have a dual effect on cardiac fibrosis through (1) mTOR inhibition and (2) inhibiting MBG-mediated profibrotic signaling and provide support for beneficial effect of a novel therapy for uremic cardiomyopathy.
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Presión Sanguínea/efectos de los fármacos , Bufanólidos/farmacología , Cardiomiopatías/patología , Inhibidores Enzimáticos/farmacología , Fibroblastos/efectos de los fármacos , Corazón/efectos de los fármacos , Inmunosupresores/farmacología , Miocardio/patología , Sirolimus/farmacología , Uremia/patología , Animales , Bufanólidos/metabolismo , Cardiomiopatías/metabolismo , Células Cultivadas , Fibroblastos/metabolismo , Fibroblastos/patología , Fibrosis , Humanos , Masculino , Nefrectomía , Ratas , Ratas Sprague-Dawley , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Uremia/metabolismoRESUMEN
The 70-kDa heat shock protein (Hsp) family in all Drosophila species includes 2 environmentally inducible family members, Hsp70 and Hsp68. Two-dimensional gel electrophoresis revealed an unusual pattern of heat shock-inducible proteins in the species of the virilis group. Trypsin fingerprinting and microsequencing of tryptic peptides using ProteinChip Array technology identified the major isoelectric variants of Hsp70 family, including Hsp68 isoforms that differ in both molecular mass and isoelectric point from those in Drosophila melanogaster. The peculiar electrophoretic mobility is consistent with the deduced amino acid sequence of corresponding hsp genes from the species of the virilis group.
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Drosophila/clasificación , Drosophila/genética , Proteínas HSP70 de Choque Térmico/genética , Proteínas HSP70 de Choque Térmico/metabolismo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Animales , Anticuerpos Monoclonales/metabolismo , Electroforesis en Gel Bidimensional , Electroforesis en Gel de Poliacrilamida , Variación Genética , Respuesta al Choque Térmico/genética , Calor , Immunoblotting , Peso Molecular , Mapeo Peptídico , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Análisis de Secuencia de ADN , Especificidad de la Especie , Tripsina/farmacologíaRESUMEN
BACKGROUND: The bioactive steroid, marinobufagenin, is an endogenous Na/K-ATPase bufadienolide inhibitor that is synthesized by adrenocortical and placental cells. Marinobufagenin binding to Na/K-ATPase initiates profibrotic cell signaling, and heightened marinobufagenin levels are implicated in the pathogenesis of hypertension, preeclampsia, and chronic kidney disease. Steroids are derived from cholesterol through the traditional steroidogenesis pathway initiated by enzyme CYP11A1, and via the acidic bile acid pathway, which is controlled by enzyme CYP27A1. The mechanism of marinobufagenin biosynthesis in mammals, however, remains unknown. METHODS AND RESULTS: Here, we show that post-transcriptional silencing of the CYP27A1 gene in human trophoblast and rat adrenocortical cells reduced the expression of CYP27A1 mRNA by 70%, reduced total bile acids 2-fold, and marinobufagenin levels by 67% when compared with nontreated cells or cells transfected with nontargeting siRNA. In contrast, silencing of the CYP11A1 gene did not affect marinobufagenin production in either cell culture, but suppressed production of progesterone 2-fold in human trophoblast cells and of corticosterone by 90% in rat adrenocortical cells when compared with cells transfected with nontargeting siRNA. In vivo, in a high-salt administration experiment, male and female Dahl salt-sensitive rats became hypertensive after 4 weeks on a high-NaCl diet, their plasma marinobufagenin levels doubled, and adrenocortical CYP27A1 mRNA and protein increased 1.6-fold and 2.0-fold. CONCLUSIONS: Therefore, the endogenous steroidal Na/K-ATPase inhibitor, marinobufagenin, is synthesized in mammalian placenta and adrenal cortex from cholesterol through the novel acidic bile acid pathway. These findings will help to understand the role of marinobufagenin in highly prevalent human cardiovascular diseases.
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Ácidos y Sales Biliares/metabolismo , Bufanólidos/metabolismo , Enfermedades Cardiovasculares/metabolismo , Colestanotriol 26-Monooxigenasa/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/antagonistas & inhibidores , Corteza Suprarrenal/metabolismo , Animales , Línea Celular Tumoral , Células Cultivadas , Colestanotriol 26-Monooxigenasa/genética , Enzima de Desdoblamiento de la Cadena Lateral del Colesterol/genética , Femenino , Humanos , Masculino , Embarazo , Interferencia de ARN , Ratas , Ratas Endogámicas Dahl , Trofoblastos/metabolismoRESUMEN
BACKGROUND: Marinobufagenin (MBG), a bufadienolide cardiotonic steroid, induces cardiovascular fibrosis. Because levels of MBG in preeclampsia are increased, and anti-MBG monoclonal antibody reduces blood pressure (BP) in a rat model of preeclampsia, we hypothesized that in preeclampsia, elevated MBG levels would be associated with the development of fibrosis in feto-placental circulation and with impairment of vascular relaxation. METHOD: We studied 16 patients with preeclampsia (systolic BP=150±4 mmHg; 28±2 years, 37±1 weeks gestational age) and 14 gestational age-matched normal pregnant women (systolic BP=112±2 mmHg). RESULTS: Preeclampsia was associated with a rise in plasma and placental levels of MBG. In preeclamptic umbilical arteries, the expression of Fli-1, a transcription factor and a negative regulator of fibrosis, was significantly reduced (P<0.001), whereas procollagen-1 expression was increased (P<0.01). As compared to control vessels, isolated rings of umbilical arteries from patients with preeclampsia demonstrated unaltered responsiveness to endothelin-1 (EC50=2.2 and 3.2 nmol/l, respectively), but exhibited an impaired response to the relaxant effect of sodium nitroprusside (EC50=1.5 vs. 32.4 nmol/l, P<.001) following endothelin-1-induced constriction. Ex-vivo treatment of normal umbilical arteries explants with 1 and 10 nmol/l MBG for 24 h mimicked the effects of preeclampsia, specifically suppressed Fli-1 and increased collagen-1 expression while impairing vasorelaxation. CONCLUSION: Our results indicate that in preeclampsia, elevated levels of MBG induce vascular fibrosis via a Fli-1-dependent mechanism which leads to an impairment of vasorelaxation, and suggest that MBG represents a potential target for therapy of this syndrome.
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Preeclampsia/metabolismo , Esteroides/metabolismo , Arterias Umbilicales/patología , Adulto , Western Blotting , Femenino , Humanos , Inmunoensayo , Embarazo , Arterias Umbilicales/metabolismo , Arterias Umbilicales/fisiopatologíaRESUMEN
We compared a series of Drosophila strains with P element insertions from -28 to -144 nucleotides 5' to the transcription start site of the Hsp70A genes-corresponding to the range of naturally occurring P element insertion sites-to elucidate the consequences of insertion site for Hsp70A gene expression. Although all insertions reduced Hsp70A expression below that of a control strain, the magnitude of the reduction was inversely related to the number of nucleotides between the transcription start site and the insertion site. A pre-existing hypothesis is that naturally occurring transposable element insertions in Hsp promoters may be beneficial in some circumstances, which may account for their retention in natural populations. In the present study, in a control line heat shock reduced fecundity, whereas in lines with P element insertions heat shock typically increased fecundity. Finally, according to cluster-specific quantitative RT-PCR, expression of the Hsp70A cluster genes was typically greater than that of the Hsp70B gene cluster genes, although the latter are more numerous and, in this case, free of P element insertions.