Unknown,Transcriptomics,Genomics,Proteomics

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Protein Microarrays Discover Angiotensinogen and PRKRIP1 as Novel Targets for Autoantibodies in Chronic Renal Disease

ABSTRACT: Biomarkers for early detection of chronic kidney disease are needed, as millions of patients suffer from chronic diseases predisposing them to kidney failure. Protein microarrays may hold utility in the discovery of auto-antibodies in other conditions not commonly considered auto-immune diseases. We hypothesized that proteins are released as a consequence of damage at a cellular level during end-organ damage from renal injury, not otherwise recognized as self-antigens, and an adaptive humoral immune response to these proteins might be detected in the blood, as a non-invasive tracker of this injury. The resultant antibodies (Ab) detected in the blood would serve as effective biomarkers for occult renal injury, enabling earlier clinical detection of chronic kidney disease than currently possible, due to the redundancy of the serum creatinine as a biomarker for early kidney injury. To screen for novel autoantibodies in chronic kidney disease, 24 protein microarrays were used to compare serum Ab from patients with chronic kidney disease against matched controls. From a panel of 38 antigens with increased Ab binding, 4 were validated in 71 individuals, with (n=50) and without (n=21) renal insufficiency. Significant elevations in the titer of novel auto-Ab were noted against Angiotensinogen (AGT) and PRKRIP1 in renal insufficiency. Current validation is underway to evaluate if these auto-Ab can provide means to follow the evolution of chronic kidney disease in patients with early stages of renal insufficiency, and if these rising titers of these auto-Ab correlate with the rate of progression of chronic kidney disease. Serum antibodies were profiled for 7 healthy individuals and 17 patients with chronic kidney disease, using the Invitrogen ProtoArray® Human Protein Microarray v3.0 platform (Invitrogen, Carlsbad, CA). This platform contains 5,056 non-redundant human proteins expressed in a baculovirus system, purified from insect cells and printed in duplicate onto a nitrocellulose-coated glass slide. Each protein is spotted twice on each array, to measure the quality of the signal intensity. Details for experiment processing and analysis follow the previous publication from our group (Li et al Proc Natl Acad Sci U S A. 2009 Mar 17;106(11):4148-53). Prospector software was used to retrieve the expression based on immune response profiling of the .gal files.

ORGANISM(S): Homo sapiens

SUBMITTER: Persis Wadia

PROVIDER: E-GEOD-23609 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Studies recently support that non-HLA antigens could be additional targets of injury in organ transplant recipients, and MICA was associated with an increased risk of graft loss. Methods: A ProtoArray platform was used to study 37 serum samples from 22 unique patients (15 renal recipients and 7 healthy controls). Thirty paired pre- and post-transplant serum samples were analyzed for detection of de novo post-transplant antibody responses in the 15 patients (10 acute rejection (AR), 5 Stable). Probes on ProtoArray and cDNA platforms (GSE: 3931) were re-annotated and compartment specific gene lists were analyzed using the integrated genomics method. Normal and transplant kidney IHC were performed for MICA antigen localization. Results: Mean MICA-Ab (antibody) signal intensity was significantly higher in transplant patients compared with healthy controls and de novo MICA-Ab were detected in 73% transplant patients. The mean post-transplant signal intensity of MICA-Ab was the highest in C4d+AR. Detection of MICA-Ab responses did not correlate with time post-transplantation, but significantly correlated with decline in graft function over the subsequent year. Integrative genomics predicted localization of the MICA antigen to the glomerulus. IHC confirmed cytoplasmic MICA staining solely in glomerular podocytes in normal kidney. In the transplant kidney, infiltrating mononuclear lymphocytes (T, B and NK) in AR had additional MICA staining. Conclusions: MICA can be highly detected regardless of graft dysfunction or AR. The intensity signal of the MICA antibody correlates with subsequent decline in graft function. The MICA antigen localizes to the glomerulus and infiltrating mononuclear cells in AR. Pre- and post-transplant serum antibodies were profiled for each patient, using the Invitrogen ProtoArrayÂ® Human Protein Microarray v3.0 platform (Invitrogen, Carlsbad, CA). This platform contains 5,056 non-redundant human proteins expressed in a baculovirus system, purified from insect cells and printed in duplicate onto a nitrocellulose-coated glass slide. Each protein is spotted twice on each array, to measure the quality of the signal intensity. Details for experiment processing and analysis follow the previous publication from our group (13). Prospector software was used to retrieve the expression based on immune response profiling of the .gal files.

Project description:Microarray technology has evolved as a powerful tool over the last decade, to identify biomarkers and study the mechanisms of diseases. We propose a novel application of integrated genomics by combining transcriptional levels with serological antibody profiling after kidney transplantation, with the aim of uncovering the relative immunogenicity of seven different renal compartments after allo-transplantation. Thirty-six paired pre- and post-transplant serum samples were examined from eighteen transplant recipients, across 5,056 protein targets on the ProtoArray V3.0 platform. Normal renal compartment-specific gene expression data from a cDNA platform were re-analyzed and both the cDNA and the ProtoArray platforms were re-annotated to most up-to-date NCBI gene identifiers; 3,835 genes/proteins are measured on both platforms. Antibody levels were ranked for individual patients and the hypergeometric enrichment statistic was applied on mapped compartment-specific expression data. We discovered that after transplantation, in addition to HLA and MICA responses, temporal alloimmune responses are seen against non-HLA antigens specific to different compartments of the kidney, with highest level responses noted against renal pelvis and cortex specific antigens. The renal medulla is of low immunogenicity as none of the outer or inner medulla specific targets generated significant post-transplant antibody responses. Immunohistochemistry confirmed pelvis and cortex specific localizations of selected targeted antigens, supporting the robust nature of this discovery. This study provides a road map of renal compartment-specific non-HLA antigenic targets responsible for generating alloimmune responses, opening the door for clinical correlations with post-transplant dysfunctional states to be determined. Keywords: alloimmune response after kidney transplantation Plasma profiling using Protein Microarray: Serum antibodies were profiled using Invitrogen ProtoArrayÂ® Human Protein Microarray v3.0 technology (Invitrogen, Carlsbad, CA). This platform contains 5,056 non-redundant human proteins expressed in a baculovirus system, purified from insect cells and printed in duplicate onto a nitrocellulose-coated glass slide. Five mL serum diluted in PBST buffer at 1:150 was applied for 90 minutes onto the Protoarray, after blocking with blocking buffer for 1 hour. The slides were then washed with 5ml fresh PBST buffer, 4 times for 10 minutes each, and probed with secondary antibody (goat anti-human Alexa 647, Molecular Probes, Eugene, OR) for 90 minutes. Finally, after a second washing with PBST buffer, the slides were dried and scanned using a fluorescent microarray scanner (GSI Luminoics Perkin-Elmer scanner). All steps were carried out on a rotating platform at 4 ÂºC. ProtoArray data acquisition and measurement: The slides were scanned at a PMT gain of 60% with a laser power of 90% and a focus point of 0 Î¼m. Fluorescence intensity data were acquired using GenePix Pro 6.0 software (Molecular devices, Sunnyvale, CA) with the appropriate â.galâ file downloaded from the ProtoArray central portal on the Invitrogen website (http://www.invitrogen.com/protoarray) by submitting the barcode of each ProtoArray slide.

Project description:Identifying the targets of immune response after allogeneic hematopoietic cell transplantation (HCT) promises to provide relevant immune therapy candidate proteins. We used protein microarrays to serologically identify Nucleolar and Spindle Associated Protein 1 (NuSAP1) and Chromatin Assembly Factor 1, subunit B (p60) [CHAF1b] as targets of new antibody responses that developed after allogeneic HCT. Western blots and ELISA validated their post-HCT recognition and enabled ELISA testing of 120 other allo-HCT patients. CHAF1b specific antibodies were predominantly detected in AML patients whereas NuSAP1 specific antibodies were exclusively detected in AML patients one year post-transplant (p<0.0001). Complete genomic exon sequencing failed to identify a nonsynonymous SNP for NuSAP1 and CHAF1b between the donor and recipient cells. Expression profiles and RT-PCR showed NuSAP1 was predominately expressed in the bone marrow CD34+CD90+ hematopoietic stem cells (HSC), leukemic cell lines and B lymphoblasts as compared to other tissues or cells. Thus, NuSAP1 is recognized as an immunogenic antigen in 65% AML patients and suggests a tumor antigen role. In conclusion, clinically important tumor antigens can be identified as new antibody targets after allogeneic HCT using high density protein microarrays Plasma Profiling using ProtoArrays: Protein microarrays were obtained (ProtoArraysâ¢ V3, Invitrogen Corporation, Carlsbad, CA) displaying 5,056 full-length human proteins, derived from the Ultimate ORF collection (Invitrogen Corp., Carlsbad, CA) printed in duplicate with N-terminal GST epitopes expressed in Baculovirus and affinity purified under native conditions maintaining their cellular enzymatic activities/native conformations. The arrays also contained control spots consisting of buffer, empty spots, and human IgG printed in four different concentrations (IgG[1] to IgG[4]). The arrays were incubated with blocking buffer for one hr followed by application of the plasma sample diluted 1:150 for 90 min. After washing the array four times for 10 min each with PBST buffer, secondary antibody was added (goat anti-human Alexa 647, Molecular Probes, Eugene, OR) for 90 min. After washing the slides with PBST buffer, the arrays were dried and fluorescent intensity was detected using a microarray scanner (GenePix 4000B, Molecular Devices, CA). All incubations were carried out on a rotating platform at 4 ÂºC. ProtoArray data acquisition and measurement: The slides were scanned at a PMT gain of 60% with a laser power of 90% and a focus point of 0 Î¼m. Fluorescence intensity data were acquired using GenePix Pro 6.0 software (Molecular devices, Sunnyvale, CA) with the appropriate â.galâ file downloaded from the ProtoArray central portal on the Invitrogen website (http://www.invitrogen.com/protoarray) by submitting the barcode of each ProtoArray slide

Project description:Signal transduction by the NF-kappaB pathway is a key regulator of a host of cellular responses to extracellular and intracellular messages. The NEMO adaptor protein lies at the top of this pathway and serves as a molecular conduit, connecting signals transmitted from upstream sensors to the downstream NF-kappaB transcription factor and subsequent gene activation. The position of NEMO within this pathway makes it an attractive target from which to search for new proteins that link NF-kappaB signaling to additional pathways and upstream effectors. In this work, we have used protein microarrays to identify novel NEMO interactors. A total of 112 protein interactors were identified, with the most statistically significant hit being the canonical NEMO interactor IKKbeta, with IKKalpha also being identified. Of the novel interactors, more than 30% were kinases, while at least 25% were involved in signal transduction. Binding of NEMO to several interactors, including CALB1, CDK2, SAG, SENP2 and SYT1, was confirmed using GST pulldown assays and coimmunoprecipitation, validating the initial screening approach. Overexpression of CALB1, CDK2 and SAG was found to stimulate transcriptional activation by NF-kappaB, while SYT1 overexpression repressed TNFalpha-dependent NF-kappaB transcriptional activation in human embryonic kidney cells. Corresponding with this finding, RNA silencing of CDK2, SAG and SENP2 reduced NF-kappaB transcriptional activation, supporting a positive role for these proteins in the NF-kappaB pathway. The identification of a host of new NEMO interactors opens up new research opportunities to improve understanding of this essential cell signaling pathway. For microarray screening, Invitrogen Protoarray v4.0 protein microarrays were used. Human NEMO expressed as a C-terminal GST fusion was purified from E. coli lysates and labelled with biotin. NEMO or biotinylated GST were applied to the microarrays and binding partners detected using streptavidin-Alexa Fluor 647. Significant interactors on both arrays were detected using Invitrogen Protoarray Prospector software and a Z-score cutoff of 3.0. Following subtraction of interactors present on the GST control array, a final set of significant NEMO interactors was derived. Full experimental details are supplied in Fenner, B. J., Scannell, M. & Prehn, J. H. M. (2010). Expanding the substantial interactome of NEMO using protein microarrays. PLoS ONE (in press).

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Protein Microarrays Discover Angiotensinogen and PRKRIP1 as Novel Targets for Autoantibodies in Chronic Renal Disease

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