RESUMEN
Podocyte injury is an early event in diabetic kidney disease and is a hallmark of glomerulopathy. MicroRNA-146a (miR-146a) is highly expressed in many cell types under homeostatic conditions, and plays an important anti-inflammatory role in myeloid cells. However, its role in podocytes is unclear. Here, we show that miR-146a expression levels decrease in the glomeruli of patients with type 2 diabetes (T2D), which correlates with increased albuminuria and glomerular damage. miR-146a levels are also significantly reduced in the glomeruli of albuminuric BTBR ob/ob mice, indicating its significant role in maintaining podocyte health. miR-146a-deficient mice (miR-146a-/-) showed accelerated development of glomerulopathy and albuminuria upon streptozotocin (STZ)-induced hyperglycemia. The miR-146a targets, Notch-1 and ErbB4, were also significantly up-regulated in the glomeruli of diabetic patients and mice, suggesting induction of the downstream TGFß signaling. Treatment with a pan-ErbB kinase inhibitor erlotinib with nanomolar activity against ErbB4 significantly suppressed diabetic glomerular injury and albuminuria in both WT and miR-146a-/- animals. Treatment of podocytes in vitro with TGF-ß1 resulted in increased expression of Notch-1, ErbB4, pErbB4, and pEGFR, the heterodimerization partner of ErbB4, suggesting increased ErbB4/EGFR signaling. TGF-ß1 also increased levels of inflammatory cytokine monocyte chemoattractant protein-1 (MCP-1) and MCP-1 induced protein-1 (MCPIP1), a suppressor of miR-146a, suggesting an autocrine loop. Inhibition of ErbB4/EGFR with erlotinib co-treatment of podocytes suppressed this signaling. Our findings suggest a novel role for miR-146a in protecting against diabetic glomerulopathy and podocyte injury. They also point to ErbB4/EGFR as a novel, druggable target for therapeutic intervention, especially because several pan-ErbB inhibitors are clinically available.
Asunto(s)
Diabetes Mellitus Experimental/metabolismo , Nefropatías Diabéticas/metabolismo , MicroARNs/metabolismo , Podocitos/metabolismo , Receptor ErbB-4/biosíntesis , Receptor Notch1/biosíntesis , Regulación hacia Arriba , Animales , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/patología , Nefropatías Diabéticas/tratamiento farmacológico , Nefropatías Diabéticas/genética , Nefropatías Diabéticas/patología , Clorhidrato de Erlotinib/farmacología , Ratones , Ratones Noqueados , MicroARNs/genética , Podocitos/patología , Receptor ErbB-4/genética , Receptor Notch1/genética , Ribonucleasas/genética , Ribonucleasas/metabolismo , Factores de Riesgo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Factor de Crecimiento Transformador beta1/genética , Factor de Crecimiento Transformador beta1/metabolismoRESUMEN
Podocytes are terminally differentiated cells of the kidney filtration barrier with a limited proliferative capacity and are the primary glomerular target for various sources of cellular stress. Accordingly, it is particularly important for podocytes to cope with stress efficiently to circumvent cell death and avoid compromising renal function. Improperly folded proteins within the endoplasmic reticulum (ER) are associated with increased cellular injury and cell death. To relieve ER stress, protein quality control mechanisms like ER-associated degradation (ERAD) are initiated. Derlin-2 is an important dislocation channel component in the ERAD pathway, having an indispensable role in clearing misfolded glycoproteins from the ER lumen. With studies linking ER stress to kidney disease, we investigated the role of derlin-2 in the susceptibility of podocytes to injury due to protein misfolding. We show that podocytes employ derlin-2 to mediate the ER quality control system to maintain cellular homeostasis in both mouse and human glomeruli. Patients with focal segmental glomerulosclerosis (FSGS) or diabetic nephropathy (DN) upregulate derlin-2 expression in response to glomerular injury, as do corresponding mouse models. In derlin-2-deficient podocytes, compensatory responses were lost under adriamycin (ADR)-induced ER dysfunction, and severe cellular injury ensued via a caspase-12-dependent pathway. Moreover, derlin-2 overexpression in vitro attenuated ADR-induced podocyte injury. Thus derlin-2 is part of a protein quality control mechanism that can rescue glomerular injury attributable to impaired protein folding pathways in the ER. Induction of derlin-2 expression in vivo may have applications in prevention and treatment of glomerular diseases.
Asunto(s)
Nefropatías Diabéticas/metabolismo , Degradación Asociada con el Retículo Endoplásmico , Retículo Endoplásmico/metabolismo , Glomeruloesclerosis Focal y Segmentaria/metabolismo , Proteínas de la Membrana/metabolismo , Podocitos/metabolismo , Animales , Apoptosis , Nefropatías Diabéticas/genética , Nefropatías Diabéticas/patología , Modelos Animales de Enfermedad , Retículo Endoplásmico/patología , Estrés del Retículo Endoplásmico , Glomeruloesclerosis Focal y Segmentaria/genética , Glomeruloesclerosis Focal y Segmentaria/patología , Humanos , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/genética , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Podocitos/patología , Pliegue de Proteína , Proteolisis , Factores de TiempoRESUMEN
Substrates of a major drug-metabolizing enzyme CYP2D6 display increased elimination during pregnancy, but the underlying mechanisms are unknown in part due to a lack of experimental models. Here, we introduce CYP2D6-humanized (Tg-CYP2D6) mice as an animal model where hepatic CYP2D6 expression is increased during pregnancy. In the mouse livers, expression of a known positive regulator of CYP2D6, hepatocyte nuclear factor 4α (HNF4α), did not change during pregnancy. However, HNF4α recruitment to CYP2D6 promoter increased at term pregnancy, accompanied by repressed expression of small heterodimer partner (SHP). In HepG2 cells, SHP repressed HNF4α transactivation of CYP2D6 promoter. In transgenic (Tg)-CYP2D6 mice, SHP knockdown led to a significant increase in CYP2D6 expression. Retinoic acid, an endogenous compound that induces SHP, exhibited decreased hepatic levels during pregnancy in Tg-CYP2D6 mice. Administration of all-trans-retinoic acid led to a significant decrease in the expression and activity of hepatic CYP2D6 in Tg-CYP2D6 mice. This study provides key insights into mechanisms underlying altered CYP2D6-mediated drug metabolism during pregnancy, laying a foundation for improved drug therapy in pregnant women.
Asunto(s)
Citocromo P-450 CYP2D6/biosíntesis , Hígado/enzimología , Embarazo/metabolismo , Receptores Citoplasmáticos y Nucleares/metabolismo , Activación Transcripcional/fisiología , Animales , Antineoplásicos/farmacocinética , Antineoplásicos/farmacología , Citocromo P-450 CYP2D6/genética , Inducción Enzimática/efectos de los fármacos , Inducción Enzimática/fisiología , Femenino , Células Hep G2 , Factor Nuclear 4 del Hepatocito/genética , Factor Nuclear 4 del Hepatocito/metabolismo , Humanos , Ratones , Ratones Transgénicos , Embarazo/genética , Regiones Promotoras Genéticas/fisiología , Receptores Citoplasmáticos y Nucleares/genética , Activación Transcripcional/efectos de los fármacos , Tretinoina/farmacocinética , Tretinoina/farmacologíaRESUMEN
Cytochrome P450 2D6 (CYP2D6), a major drug-metabolizing enzyme, is responsible for metabolism of approximately 25% of marketed drugs. Clinical evidence indicates that metabolism of CYP2D6 substrates is increased during pregnancy, but the underlying mechanisms remain unclear. To identify transcription factors potentially responsible for CYP2D6 induction during pregnancy, a panel of genes differentially expressed in the livers of pregnant versus nonpregnant CYP2D6-humanized (tg-CYP2D6) mice was compiled via microarray experiments followed by real-time quantitative reverse-transcription polymerase chain reaction(qRT-PCR) verification. As a result, seven transcription factors-activating transcription factor 5 (ATF5), early growth response 1 (EGR1), forkhead box protein A3 (FOXA3), JUNB, Krüppel-like factor 9 (KLF9), KLF10, and REV-ERBα-were found to be up-regulated in liver during pregnancy. Results from transient transfection and promoter reporter gene assays indicate that KLF9 itself is a weak transactivator of CYP2D6 promoter but significantly enhances CYP2D6 promoter transactivation by hepatocyte nuclear factor 4 (HNF4α), a known transcriptional activator of CYP2D6 expression. The results from deletion and mutation analysis of CYP2D6 promoter activity identified a KLF9 putative binding motif at -22/-14 region to be critical in the potentiation of HNF4α-induced transactivation of CYP2D6. Electrophoretic mobility shift assays revealed a direct binding of KLF9 to the putative KLF binding motif. Results from chromatin immunoprecipitation assay showed increased recruitment of KLF9 to CYP2D6 promoter in the livers of tg-CYP2D6 mice during pregnancy. Taken together, our data suggest that increased KLF9 expression is in part responsible for CYP2D6 induction during pregnancy via the potentiation of HNF4α transactivation of CYP2D6.
Asunto(s)
Citocromo P-450 CYP2D6/genética , Factores de Transcripción de Tipo Kruppel/fisiología , Hígado/enzimología , Preñez/metabolismo , Animales , Femenino , Células HEK293 , Factor Nuclear 4 del Hepatocito/química , Factor Nuclear 4 del Hepatocito/fisiología , Humanos , Factores de Transcripción de Tipo Kruppel/química , Masculino , Ratones , Embarazo , Regiones Promotoras GenéticasRESUMEN
Sulfotransferase (SULT) 2A1 catalyzes sulfonation of drugs and endogenous compounds and plays an important role in xenobiotic metabolism as well as in the maintenance of steroid and lipid homeostasis. A recent study showed that 17ß-estradiol (E2) increases the mRNA levels of SULT2A1 in human hepatocytes. Here we report the underlying molecular mechanisms. E2 enhanced SULT2A1 expression in human hepatocytes and HepG2-ER cells (HepG2 stably expressing ERα). SULT2A1 induction by E2 was abrogated by antiestrogen ICI 182,780, indicating a key role of ERα in the induction. Results from deletion and mutation assays of SULT2A1 promoter revealed three cis-elements located within -257/+140 region of SULT2A1 that are potentially responsible for the induction. Chromatin immunoprecipitation assay verified the recruitment of ERα to the promoter region. Electrophoretic mobility shift assays revealed that AP-1 proteins bind to one of the cis-elements. Interestingly, SULT2A1 promoter assays using ERα mutants revealed that the DNA-binding domain of ERα is indispensable for SULT2A1 induction by E2, suggesting that direct ERα binding to the SULT2A1 promoter is also necessary for the induction. Taken together, our results indicate that E2 enhances SULT2A1 expression by both the classical and nonclassical mechanisms of ERα action.
Asunto(s)
Estradiol/farmacología , Receptor alfa de Estrógeno/metabolismo , Hepatocitos/efectos de los fármacos , Sulfotransferasas/biosíntesis , Western Blotting , Técnicas de Cultivo de Célula , Inmunoprecipitación de Cromatina , Ensayo de Cambio de Movilidad Electroforética , Inducción Enzimática , Receptor alfa de Estrógeno/genética , Células Hep G2 , Hepatocitos/enzimología , Hepatocitos/metabolismo , Humanos , Mutación , Regiones Promotoras Genéticas , Unión Proteica , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sulfotransferasas/genética , Transfección , Regulación hacia ArribaRESUMEN
Ubiquitination plays an important role in the DNA damage response. We identified a novel interaction of the E3 ubiquitin ligase RNF8 with Nbs1, a key regulator of DNA double-strand break (DSB) repair. We found that Nbs1 is ubiquitinated both before and after DNA damage and is a direct ubiquitination substrate of RNF8. We also identified key residues on Nbs1 that are ubiquitinated by RNF8. By using laser microirradiation and live-cell imaging, we observed that RNF8 and its ubiquitination activity are important for promoting optimal binding of Nbs1 to DSB-containing chromatin. We also demonstrated that RNF8-mediated ubiquitination of Nbs1 contributes to the efficient and stable binding of Nbs1 to DSBs and is important for HR-mediated DSB repair. Taken together, these studies suggest that Nbs1 is one important target of RNF8 to regulate DNA DSB repair.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Roturas del ADN de Doble Cadena , Reparación del ADN/fisiología , Proteínas de Unión al ADN/metabolismo , Recombinación Homóloga/fisiología , Proteínas Nucleares/metabolismo , Ubiquitinación/fisiología , Proteínas de Ciclo Celular/genética , Línea Celular Tumoral , Reparación del ADN/efectos de la radiación , Proteínas de Unión al ADN/genética , Recombinación Homóloga/efectos de la radiación , Humanos , Rayos Láser/efectos adversos , Proteínas Nucleares/genética , Ubiquitina-Proteína Ligasas , Ubiquitinación/efectos de la radiaciónRESUMEN
Results from clinical studies suggest that pregnancy alters hepatic drug metabolism in a cytochrome P450 (P450) isoform-specific manner, and rising concentrations of female hormones are potentially responsible for the changes. The objective of this study was to comprehensively characterize the effects of estrogen and progesterone on the expression and activity of major drug-metabolizing P450s. To this end, primary human hepatocytes were treated with estradiol and progesterone, and mRNA expression and activity levels of 10 different P450 isoforms were determined. The results showed that estradiol enhances CYP2A6, CYP2B6, and CYP3A4 expression, whereas progesterone induces CYP2A6, CYP2B6, CYP2C8, CYP3A4, and CYP3A5 expression. The induction was mainly observed when the average hormone concentrations were at the levels reached during pregnancy, suggesting that these effects are likely pregnancy-specific. Estradiol also increased enzyme activities of CYP2C9 and CYP2E1 without affecting the mRNA expression levels by unknown mechanisms. Taken together, our results show differential effects of estrogen and progesterone on P450 expression, suggesting involvement of different regulatory mechanisms in female hormone-mediated P450 regulation. Our findings potentially provide a basis in mechanistic understanding for altered drug metabolism during pregnancy.
Asunto(s)
Sistema Enzimático del Citocromo P-450/metabolismo , Estradiol/farmacología , Hepatocitos/efectos de los fármacos , Progesterona/farmacología , Adulto , Anciano , Biotransformación , Células Cultivadas , Sistema Enzimático del Citocromo P-450/biosíntesis , Sistema Enzimático del Citocromo P-450/genética , Relación Dosis-Respuesta a Droga , Inducción Enzimática , Estradiol/metabolismo , Femenino , Hepatocitos/enzimología , Humanos , Isoenzimas , Persona de Mediana Edad , Embarazo , Cultivo Primario de Células , Progesterona/metabolismo , ARN Mensajero/biosíntesis , Especificidad por Sustrato , Factores de TiempoRESUMEN
Elevation in soluble urokinase receptor (suPAR) and proteinuria are common signs in patients with moderate to severe coronavirus disease 2019 (COVID-19). Here we characterize a new type of proteinuria originating as part of a viral response. Inoculation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes increased suPAR levels and glomerulopathy in African green monkeys. Using an engineered mouse model with high suPAR expression, inhaled variants of SARS-CoV-2 spike S1 protein elicite proteinuria that could be blocked by either suPAR antibody or SARS-CoV-2 vaccination. In a cohort of 1991 COVID-19 patients, suPAR levels exhibit a stepwise association with proteinuria in non-Omicron, but not in Omicron infections, supporting our findings of biophysical and functional differences between variants of SARS-CoV-2 spike S1 protein and their binding to podocyte integrins. These insights are not limited to SARS-CoV-2 and define viral response proteinuria (VRP) as an innate immune mechanism and co-activation of podocyte integrins.
Asunto(s)
COVID-19 , Podocitos , Animales , Ratones , Chlorocebus aethiops , Humanos , Vacunas contra la COVID-19 , Receptores del Activador de Plasminógeno Tipo Uroquinasa/genética , SARS-CoV-2 , Integrinas , ProteinuriaRESUMEN
Human pregnancy is known to influence hepatic drug metabolism in a cytochrome (P450)-specific manner. However, the underlying mechanisms remain unknown, in part due to a lack of experimental models to study altered drug metabolism during pregnancy. In this study, we examined how pregnancy influences expression of major P450 isoforms in mice. Liver tissues were isolated from female FVB/N-mice at different gestational time points: prepregnancy, 7, 14, and 21 days of pregnancy, and 7 days postpartum. mRNA expression levels of major P450 isoforms (Cyp1a2, Cyp2a5, Cyp2b10, Cyp2c37, Cyp2d22, Cyp2e1, Cyp3a11, and Cyp3a41) in the liver tissues were determined by quantitative real-time polymerase chain reaction. Whereas Cyp2a5 expression was unchanged, Cyp3a41 expression was significantly increased during pregnancy. In contrast, expression of Cyp1a2, Cyp2c37, Cyp2d22, Cyp2e1, and Cyp3a11 was decreased. Expression of Cyp2d22 and Cyp2e1 isoforms correlated with that of peroxisome proliferator-activated receptor (PPAR)α in the mouse livers, suggesting potential involvement of PPARα in down-regulation of the P450 expression during pregnancy. Effects of pregnancy on expression of other P450 mouse isoforms as well as on in vivo drug disposition remain to be characterized. These results provide a guide for future studies on P450 regulation during pregnancy.
Asunto(s)
Sistema Enzimático del Citocromo P-450/genética , Regulación Enzimológica de la Expresión Génica , Hígado/enzimología , Embarazo/metabolismo , Animales , Citocinas/genética , Femenino , Edad Gestacional , Isoenzimas , Hígado/inmunología , Ratones , Ratones Endogámicos , Embarazo/inmunología , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Transcripción/genética , Regulación hacia ArribaRESUMEN
A subset of gastric carcinomas shows histologic evidence of a multistep process, progressing from gastric adenoma to gastric carcinoma. We examined gene expression changes during the gastric adenoma-carcinoma sequence in 26 snap-frozen samples (normal mucosa, adenoma, and carcinoma samples from eight patients and two additional carcinomas) by oligonucleotide microarray. Unsupervised hierarchical clustering analysis demonstrated differential gene expression between gastric normal mucosa, adenomas and carcinomas. We identified 319 and 422 genes differentially regulated in adenoma and carcinoma, respectively, relative to normal mucosa, using a combination of Welch's t-test and fold-change analysis. Applying a combination of robust multi-category support vector machines to the data, reveal that 39 and 21 genes were gradually up- and down-regulated, respectively, in succession in normal mucosa, adenoma, and carcinoma samples. We validated gene expression levels of four genes: hydroxyprostaglandin dehydrogenase 15 (HPGD), follistatin-like 1, trefoil factor 1 (TTF1) and trefoil factor 2 (TFF2) by RT-PCR and found direct correlation with microarray results. The expressions of the TFF2 and HPGD genes were further evaluated by immunohistochemistry in 103 adenomas and 70 carcinomas; expression of both proteins was decreased in these tissues. The progressive alteration in gene expression in the transition from normal mucosa to carcinoma suggests that these changes may play critical roles in gastric carcinogenesis.
Asunto(s)
Adenoma/genética , Carcinoma/genética , Mucosa Gástrica/metabolismo , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Neoplasias Gástricas/genética , Adenoma/enzimología , Adenoma/patología , Anciano , Anciano de 80 o más Años , Carcinoma/enzimología , Carcinoma/patología , Análisis por Conglomerados , Regulación hacia Abajo/genética , Femenino , Mucosa Gástrica/enzimología , Mucosa Gástrica/patología , Genes Relacionados con las Neoplasias/genética , Humanos , Hidroxiprostaglandina Deshidrogenasas/genética , Hidroxiprostaglandina Deshidrogenasas/metabolismo , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Péptidos/genética , Péptidos/metabolismo , Reproducibilidad de los Resultados , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/genética , Neoplasias Gástricas/enzimología , Neoplasias Gástricas/patología , Factor Trefoil-2 , Regulación hacia Arriba/genéticaRESUMEN
BACKGROUND: Nephrotic syndrome (NS) is associated with kidney podocyte injury and may occur as part of thyroid autoimmunity such as Graves' disease. Therefore, the present study was designed to ascertain if and how podocytes respond to and regulate the input of biologically active thyroid hormone (TH), 3,5,3'-triiodothyronine (T3); and also to decipher the pathophysiological role of type 3 deiodinase (D3), a membrane-bound selenoenzyme that inactivates TH, in kidney disease. METHODS: To study D3 function in healthy and injured (PAN, puromycin aminonucleoside and LPS, Lipopolysaccharide-mediated) podocytes, immunofluorescence, qPCR and podocyte-specific D3 knockout mouse were used. Surface plasmon resonance (SPR), co-immunoprecipitation and Proximity Ligation Assay (PLA) were used for the interaction studies. FINDINGS: Healthy podocytes expressed D3 as the predominant deiodinase isoform. Upon podocyte injury, levels of Dio3 transcript and D3 protein were dramatically reduced both in vitro and in the LPS mouse model of podocyte damage. D3 was no longer directed to the cell membrane, it accumulated in the Golgi and nucleus instead. Further, depleting D3 from the mouse podocytes resulted in foot process effacement and proteinuria. Treatment of mouse podocytes with T3 phenocopied the absence of D3 and elicited activation of αvß3 integrin signaling, which led to podocyte injury. We also confirmed presence of an active thyroid stimulating hormone receptor (TSH-R) on mouse podocytes, engagement and activation of which resulted in podocyte injury. INTERPRETATION: The study provided a mechanistic insight into how D3-αvß3 integrin interaction can minimize T3-dependent integrin activation, illustrating how D3 could act as a renoprotective thyrostat in podocytes. Further, injury caused by binding of TSH-R with TSH-R antibody, as found in patients with Graves' disease, explained a plausible link between thyroid disorder and NS. FUNDING: This work was supported by American Thyroid Association (ATA-2018-050.R1).
Asunto(s)
Homeostasis/fisiología , Yoduro Peroxidasa/metabolismo , Podocitos/metabolismo , Animales , Células Cultivadas , Humanos , Integrina alfaVbeta3/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteinuria/metabolismo , Puromicina Aminonucleósido/metabolismo , Receptores de Tirotropina/metabolismo , Transducción de Señal/fisiología , Hormonas Tiroideas/metabolismo , Triyodotironina/metabolismoRESUMEN
Frameshift and nonsense mutations are common in tumors with microsatellite instability, and mRNAs from these mutated genes have premature termination codons (PTCs). Abnormal mRNAs containing PTCs are normally degraded by the nonsense-mediated mRNA decay (NMD) system. However, PTCs located within 50-55 nucleotides of the last exon-exon junction are not recognized by NMD (NMD-irrelevant), and some PTC-containing mRNAs can escape from the NMD system (NMD-escape). We investigated protein expression from NMD-irrelevant and NMD-escape PTC-containing mRNAs by Western blotting and transfection assays. We demonstrated that transfection of NMD-irrelevant PTC-containing genomic DNA of MARCKS generates truncated protein. In contrast, NMD-escape PTC-containing versions of hMSH3 and TGFBR2 generate normal levels of mRNA, but do not generate detectable levels of protein. Transfection of NMD-escape mutant TGFBR2 genomic DNA failed to generate expression of truncated proteins, whereas transfection of wild-type TGFBR2 genomic DNA or mutant PTC-containing TGFBR2 cDNA generated expression of wild-type protein and truncated protein, respectively. Our findings suggest a novel mechanism of gene expression regulation for PTC-containing mRNAs in which the deleterious transcripts are regulated either by NMD or translational repression.
Asunto(s)
Codón de Terminación/fisiología , Neoplasias Colorrectales/genética , Mutación del Sistema de Lectura/genética , Regulación de la Expresión Génica/genética , Inestabilidad de Microsatélites , ARN Mensajero/genética , Regiones no Traducidas 3'/fisiología , Ácido Anhídrido Hidrolasas , Línea Celular Tumoral , Enzimas Reparadoras del ADN/genética , Proteínas de Unión al ADN/genética , Humanos , Péptidos y Proteínas de Señalización Intracelular , Proteínas de la Membrana/biosíntesis , Proteína 3 Homóloga de MutS , Mutación Missense , Sustrato de la Proteína Quinasa C Rico en Alanina Miristoilada , Proteínas de Neoplasias/análisis , Proteínas Serina-Treonina Quinasas/biosíntesis , Receptor Tipo II de Factor de Crecimiento Transformador beta , Receptores de Factores de Crecimiento Transformadores beta/biosíntesis , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Soluble urokinase receptor (suPAR) is a circulatory molecule that activates αvß3 integrin on podocytes, causes foot process effacement, and contributes to proteinuric kidney disease. While active integrin can be targeted by antibodies and small molecules, endogenous inhibitors haven't been discovered yet. Here we report what we believe is a novel renoprotective role for the inducible costimulator ligand (ICOSL) in early kidney disease through its selective binding to podocyte αvß3 integrin. Contrary to ICOSL's immune-regulatory role, ICOSL in nonhematopoietic cells limited the activation of αvß3 integrin. Specifically, ICOSL contains the arginine-glycine-aspartate (RGD) motif, which allowed for a high-affinity and selective binding to αvß3 and modulation of podocyte adhesion. This binding was largely inhibited either by a synthetic RGD peptide or by a disrupted RGD sequence in ICOSL. ICOSL binding favored the active αvß3 rather than the inactive form and showed little affinity for other integrins. Consistent with the rapid induction of podocyte ICOSL by inflammatory stimuli, glomerular ICOSL expression was increased in biopsies of early-stage human proteinuric kidney diseases. Icosl deficiency in mice resulted in an increased susceptibility to proteinuria that was rescued by recombinant ICOSL. Our work identified a potentially novel role for ICOSL, which serves as an endogenous αvß3-selective antagonist to maintain glomerular filtration.
Asunto(s)
Ligando Coestimulador de Linfocitos T Inducibles , Integrina alfaVbeta3 , Fallo Renal Crónico , Podocitos , Proteinuria , Secuencias de Aminoácidos , Animales , Tasa de Filtración Glomerular/efectos de los fármacos , Tasa de Filtración Glomerular/genética , Tasa de Filtración Glomerular/inmunología , Humanos , Ligando Coestimulador de Linfocitos T Inducibles/genética , Ligando Coestimulador de Linfocitos T Inducibles/inmunología , Ligando Coestimulador de Linfocitos T Inducibles/farmacología , Integrina alfaVbeta3/antagonistas & inhibidores , Integrina alfaVbeta3/genética , Integrina alfaVbeta3/inmunología , Fallo Renal Crónico/tratamiento farmacológico , Fallo Renal Crónico/genética , Fallo Renal Crónico/inmunología , Fallo Renal Crónico/patología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Podocitos/inmunología , Podocitos/patología , Proteinuria/tratamiento farmacológico , Proteinuria/genética , Proteinuria/inmunología , Proteinuria/patologíaRESUMEN
Soluble urokinase plasminogen activator receptor (suPAR) is an immune-derived circulating signaling molecule that has been implicated in chronic kidney disease, such as focal segmental glomerulosclerosis (FSGS). Typically, native uPAR (isoform 1) translates to a 3-domain protein capable of binding and activating integrins, yet the function of additional isoforms generated by alternative splicing is unknown. Here, we characterized mouse uPAR isoform 2 (msuPAR2), encoding domain I and nearly one-half of domain II, as a dimer in solution, as revealed by 3D electron microscopy structural analysis. In vivo, msuPAR2 transgenic mice exhibited signs of severe renal disease characteristic of FSGS with proteinuria, loss of kidney function, and glomerulosclerosis. Sequencing of the glomerular RNAs from msuPAR2-Tg mice revealed a differentially expressed gene signature that includes upregulation of the suPAR receptor Itgb3, encoding ß3 integrin. Crossing msuPAR2-transgenic mice with 3 different integrin ß3 deficiency models rescued msuPAR2-mediated kidney function. Further analyses indicated a central role for ß3 integrin and c-Src in msuPAR2 signaling and in human FSGS kidney biopsies. Administration of Src inhibitors reduced proteinuria in msuPAR2-transgenic mice. In conclusion, msuPAR2 may play an important role in certain forms of scarring kidney disease.
Asunto(s)
Enfermedades Renales/genética , Receptores del Activador de Plasminógeno Tipo Uroquinasa/química , Receptores del Activador de Plasminógeno Tipo Uroquinasa/genética , Adipocitos/citología , Animales , Biopsia , Modelos Animales de Enfermedad , Células HEK293 , Humanos , Ratones , Ratones Transgénicos , Microscopía Electrónica , Podocitos/citología , Dominios Proteicos , Isoformas de Proteínas , Multimerización de Proteína , Receptor PAR-2/genética , Estudios Retrospectivos , Transducción de SeñalRESUMEN
BACKGROUND AND METHODS: Despite the overwhelming clinical significance of metastases, the cellular and molecular mechanisms involved are largely unknown. In order to define significant differences between primary colon carcinomas and their metastases, we analyzed gene expression profiles of 12 sets of triple-paired tissues using 19 K human oligonucleotide microarrays. A total of 36 microarray experiments were analyzed by unsupervised two-way hierarchical clustering and multi-dimensional scaling (MDS). RESULTS: Both methods completely distinguished normal mucosa from carcinoma, but failed to demonstrate a complete classification of primary and metastatic carcinomas. We found a separable tendency to be classified into the primary and metastatic colon carcinomas by MDS. In supervised hierarchical clustering, we identified 80 genes that were differentially expressed between paired primary and metastatic colon carcinomas. The 80 identified genes also successfully distinguished three validation sets of primary and lung-metastatic colon carcinomas. A specific set of genes was identified that distinguished the metastasis from the corresponding primary tumor in nearly half of the metastases analyzed. CONCLUSIONS: We suggest that a more accurate model of the metastatic potential is based on a global tumor expression pattern along with the appearance of distinct metastatic variants. This molecular profiling may be useful for the future study of colon cancer metastasis.
Asunto(s)
Neoplasias Colorrectales/genética , Perfilación de la Expresión Génica , Neoplasias Hepáticas/genética , Anciano , Neoplasias Colorrectales/patología , Neoplasias Colorrectales/terapia , Femenino , Humanos , Neoplasias Hepáticas/secundario , Neoplasias Hepáticas/terapia , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de OligonucleótidosRESUMEN
Soluble urokinase plasminogen activator receptor (suPAR) independently predicts chronic kidney disease (CKD) incidence and progression. Apolipoprotein L1 (APOL1) gene variants G1 and G2, but not the reference allele (G0), are associated with an increased risk of CKD in individuals of recent African ancestry. Here we show in two large, unrelated cohorts that decline in kidney function associated with APOL1 risk variants was dependent on plasma suPAR levels: APOL1-related risk was attenuated in patients with lower suPAR, and strengthened in those with higher suPAR levels. Mechanistically, surface plasmon resonance studies identified high-affinity interactions between suPAR, APOL1 and αvß3 integrin, whereby APOL1 protein variants G1 and G2 exhibited higher affinity for suPAR-activated avb3 integrin than APOL1 G0. APOL1 G1 or G2 augments αvß3 integrin activation and causes proteinuria in mice in a suPAR-dependent manner. The synergy of circulating factor suPAR and APOL1 G1 or G2 on αvß3 integrin activation is a mechanism for CKD.
Asunto(s)
Apolipoproteínas/genética , Integrina alfaVbeta3/metabolismo , Lipoproteínas HDL/genética , Podocitos/metabolismo , Proteinuria/genética , Receptores del Activador de Plasminógeno Tipo Uroquinasa/metabolismo , Insuficiencia Renal Crónica/genética , Adolescente , Adulto , Negro o Afroamericano , Anciano , Alelos , Animales , Apolipoproteína L1 , Apolipoproteínas/metabolismo , Estudios de Cohortes , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Lipoproteínas HDL/metabolismo , Masculino , Ratones , Persona de Mediana Edad , Proteinuria/metabolismo , Insuficiencia Renal Crónica/metabolismo , Resonancia por Plasmón de Superficie , Adulto JovenRESUMEN
Genetic variations in the ITGAM gene (encoding CD11b) strongly associate with risk for systemic lupus erythematosus (SLE). Here we have shown that 3 nonsynonymous ITGAM variants that produce defective CD11b associate with elevated levels of type I interferon (IFN-I) in lupus, suggesting a direct link between reduced CD11b activity and the chronically increased inflammatory status in patients. Treatment with the small-molecule CD11b agonist LA1 led to partial integrin activation, reduced IFN-I responses in WT but not CD11b-deficient mice, and protected lupus-prone MRL/Lpr mice from end-organ injury. CD11b activation reduced TLR-dependent proinflammatory signaling in leukocytes and suppressed IFN-I signaling via an AKT/FOXO3/IFN regulatory factor 3/7 pathway. TLR-stimulated macrophages from CD11B SNP carriers showed increased basal expression of IFN regulatory factor 7 (IRF7) and IFN-ß, as well as increased nuclear exclusion of FOXO3, which was suppressed by LA1-dependent activation of CD11b. This suggests that pharmacologic activation of CD11b could be a potential mechanism for developing SLE therapeutics.
Asunto(s)
Antígeno CD11b/inmunología , Lupus Eritematoso Sistémico/inmunología , Macrófagos/inmunología , Receptores Toll-Like/inmunología , Animales , Antígeno CD11b/genética , Femenino , Proteína Forkhead Box O3/genética , Proteína Forkhead Box O3/inmunología , Humanos , Factor 3 Regulador del Interferón/genética , Factor 3 Regulador del Interferón/inmunología , Factor 7 Regulador del Interferón/genética , Factor 7 Regulador del Interferón/inmunología , Interferón Tipo I/genética , Interferón Tipo I/inmunología , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/patología , Macrófagos/patología , Masculino , Ratones , Ratones Endogámicos MRL lpr , Polimorfismo de Nucleótido Simple , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/inmunología , Receptores Toll-Like/genéticaRESUMEN
Electrophoretic mobility shift assay (EMSA) is an invaluable tool to study interaction of proteins with DNA. Estrogens are major female hormones and modulate biological function through estrogen receptor (ER). ER regulates its target gene expression via the classical mechanism in which ER directly binds to its target gene promoter or the nonclassical mechanism involving tethering of ER to other transcription factors (such as AP-1 proteins). Here, we describe the EMSA to examine the nonclassical mechanism of ER action in regulation of a gene CYP2B6 by using competition and supershift assays.
Asunto(s)
Citocromo P-450 CYP2B6/metabolismo , Ensayo de Cambio de Movilidad Electroforética , Estrógenos/farmacología , Hepatocitos/efectos de los fármacos , Sitios de Unión , Unión Competitiva , Citocromo P-450 CYP2B6/genética , Receptor alfa de Estrógeno/agonistas , Receptor alfa de Estrógeno/metabolismo , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Células Hep G2 , Hepatocitos/enzimología , Humanos , Regiones Promotoras Genéticas , Unión Proteica , Factor de Transcripción AP-1/metabolismo , Flujo de TrabajoRESUMEN
We have recently reported that transactivation of cytochrome P450 (CYP) 2D6 promoter by hepatocyte nuclear factor (HNF) 4α is enhanced during pregnancy, and this is triggered in part by altered expression of small heterodimer partner (SHP) and Krüppel-like factor 9 (KLF9). The objective of this study is to determine whether this is conserved for mouse endogenous Cyp2d gene(s). Among the eight Cyp2d homologs of mouse we examined, only Cyp2d40 expression was found induced (by 6-fold) at term pregnancy as compared to pre-pregnancy level. In mice where hepatic Hnf4α was knocked-down, the pregnancy-mediated increase in Cyp2d40 expression was abrogated. Results from transient transfection, promoter reporter assays, and electrophoretic mobility shift assays indicated that HNF4α transactivates Cyp2d40 promoter via direct binding to -117/-105 of the gene. Chromatin immunoprecipitation assay showed a 2.3-fold increase in HNF4α recruitment to Cyp2d40 promoter during pregnancy. Results from mice treated with an SHP inducer (i.e., GW4064) and HepG2 cells co-transfected with KLF9 suggest that neither SHP nor KLF9 is involved in the increased HNF4α transactivation of Cyp2d40 promoter during pregnancy. Together, our results indicate that while the underlying molecular mechanism is different from that for CYP2D6, Cyp2d40 is induced during pregnancy through enhanced transactivation by HNF4α.
Asunto(s)
Sistema Enzimático del Citocromo P-450/genética , Factor Nuclear 4 del Hepatocito/genética , Regiones Promotoras Genéticas , Activación Transcripcional , Animales , Sistema Enzimático del Citocromo P-450/metabolismo , Femenino , Genes Reporteros , Células HEK293 , Células Hep G2 , Factor Nuclear 4 del Hepatocito/metabolismo , Humanos , Isoenzimas/genética , Isoenzimas/metabolismo , Isoxazoles/farmacología , Factores de Transcripción de Tipo Kruppel/genética , Factores de Transcripción de Tipo Kruppel/metabolismo , Luciferasas/genética , Luciferasas/metabolismo , Ratones , Ratones Transgénicos , Embarazo , Receptores Citoplasmáticos y Nucleares/agonistas , Receptores Citoplasmáticos y Nucleares/genética , Receptores Citoplasmáticos y Nucleares/metabolismo , Transducción de SeñalRESUMEN
Pregnancy alters the rate and extent of drug metabolism, but little is known about the underlying molecular mechanism. We have found that 17ß-estradiol (E2) upregulates expression of the major drug-metabolizing enzyme CYP2B6 in primary human hepatocytes. Results from promoter reporter assays in HepG2 cells revealed that E2 activates constitutive androstane receptor (CAR) and enhances promoter activity of CYP2B6, for which high concentrations of E2 reached during pregnancy were required. E2 triggered nuclear translocation of CAR in primary rat hepatocytes that were transiently transfected with human CAR as well as in primary human hepatocytes, further confirming transactivation of CAR by E2. E2-activated estrogen receptor (ER) also enhanced CYP2B6 promoter activity. The DNA-binding domain of ER was not required for the induction of CYP2B6 promoter activity by E2, suggesting involvement of a non-classical mechanism of ER action. Results from deletion and mutation assays as well as electrophorectic mobility shift and supershift assays revealed that two AP-1 binding sites (-1782/-1776 and -1664/-1658 of CYP2B6) are critical for ER-mediated activation of the CYP2B6 promoter by E2. Concurrent activation of both ER and CAR by E2 enhanced CYP2B6 expression in a synergistic manner. Our data demonstrate that at high concentrations reached during pregnancy, E2 activates both CAR and ER that synergistically induce CYP2B6 expression. These results illustrate pharmacological activity of E2 that would likely become prominent during pregnancy.