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Novel probes for protein chip applications.

Protein microarrays (protein chips), due to their high throughput, have great potential to reduce the cycle time of drug discovery and to improve the efficiency of medical diagnostics. A great deal of effort has been made to facilitate the development of protein chips, such as the antibody microarrays. High-throughput fabrication of purified high-affinity probes is now one of the bottlenecks for protein microarrays. We discuss here three novel strategies to fabricate probes, namely, single chain antibodies displayed by phage, protein-oligonucleotide conjugates, and aptamers, which are promising in the protein chip technology.

Antibodies↗

The application of proteomics to diabetes.

Poteomics is the investigation of all the proteins and their various modifications making up a system, be that a cell, tissue or organism. The techniques involved in proteomics allow the global screening of complex samples of proteins and provide qualitative and quantitative evidence of altered protein expression. This lends itself to the investigation of the molecular mechanisms underpinning disease processes and the effects of treatment. This review describes the main techniques of proteomics and how they have begun to be applied to diabetes research.

Adipose Tissue↗

Profiling of acyl-CoA oxidase-deficient and peroxisome proliferator Wy14,643-treated mouse liver protein by surface-enhanced laser desorption/ionization ProteinChip Biology System.

Peroxisome proliferators induce hepatic peroxisome proliferation and hepatocellular carcinomas in rodents. These chemicals increase the expression of the peroxisomal beta-oxidation pathway and the cytochrome P-450 4A family, which metabolizes lipids, including fatty acids. Mice lacking fatty acyl-CoA oxidase (AOX-/-), the first enzyme of the peroxisomal beta-oxidation system, exhibit extensive microvesicular steatohepatitis, leading to hepatocellular regeneration and massive peroxisome proliferation. To investigate proteins involved in peroxisome proliferation, we adopted a novel surface-enhanced laser desorption/ionization (SELDI) ProteinChip technology to compare the protein profiles of control (wild-type), AOX-/-, and wild-type mice treated with peroxisome proliferator, Wy-14,643. The results indicated that the protein profiles of AOX-/- mice were similar to the wild-type mice treated with Wy14,643, but significantly different from the nontreated wild-type mice. Using four different ProteinChip Arrays, a total of 40 protein peaks showed more than twofold changes. Among these differentially expressed peaks, a downregulated peak was identified as the major urinary protein in both AOX-/- and Wyl4,643-treated mice by SELDI. The identification of MUP was further confirmed by two-dimensional electrophoresis and liquid chromatography coupled tandem mass spectrometry (LC-MS-MS). This SELDI method offers several technical advantages for detection of differentially expressed proteins, including ease and speed of screening, no need for chromatographic processing, and small sample size.

Acyl-CoA Oxidase↗

Transglutaminase type II is a key element in the regulation of the anti-inflammatory response elicited by apoptotic cell engulfment.

A key feature of the macrophage-dependent clearance of apoptotic cells is the down-regulation of proinflammatory cytokines. Deficiency in the phagocytosis of apoptotic cells is often associated with the development of inflammatory reactions, resulting in chronic inflammatory and autoimmune diseases. The molecular mechanisms that regulate the engulfment process and particularly the immunomodulatory factors involved are still largely unknown in mammals. We have previously reported that the ablation of transglutaminase type II (TG2) in mice results in the defective clearance of apoptotic cells associated with the development of splenomegaly, autoantibodies, and glomerulonephritis. In this study we have investigated the mechanisms at the basis of the development of inflammation/autoimmunity associated with the defective clearance of apoptotic cells characterizing TG2 knockout mice. To this aim we compared the macrophage response to apoptotic cell exposure in wild-type vs TG2-null mice. We demonstrated that the lack of TG2 results in an impaired capacity of macrophages to engulf, but not to bind, apoptotic cells, which is paralleled by an abnormal inflammatory response both in vivo and in vitro. We have identified a differential response in the release of several cytokines in TG2(-/-) vs wild-type mice. Particularly relevant is the finding that both TGF-beta and IL-12 regulations were significantly altered in the absence of TG2. These results help explain the autoimmune phenotype developed by these mice and suggest that TG2 is a key regulatory element of the anti-inflammatory features of apoptosis.

Animals↗

Translational regulation of autoimmune inflammation and lymphoma genesis by programmed cell death 4.

Both inflammatory diseases and cancer are associated with heightened protein translation. However, the mechanisms of translational regulation and the roles of translation factors in these diseases are not clear. Programmed cell death 4 (PDCD4) is a newly described inhibitor of protein translation. To determine the roles of PDCD4 in vivo, we generated PDCD4-deficient mice by gene targeting. We report here that mice deficient in PDCD4 develop spontaneous lymphomas and have a significantly reduced life span. Most tumors are of the B lymphoid origin with frequent metastasis to liver and kidney. However, PDCD4-deficient mice are resistant to inflammatory diseases such as autoimmune encephalomyelitis and diabetes. Mechanistic studies reveal that upon activation, PDCD4-deficient lymphocytes preferentially produce cytokines that promote oncogenesis but inhibit inflammation. These results establish that PDCD4 controls lymphoma genesis and autoimmune inflammation by selectively inhibiting protein translation in the immune system.

Animals↗

14-3-3 interacts with the tumor suppressor tuberin at Akt phosphorylation site(s).

Tuberin, the product of the tuberous sclerosis complex 2 tumor suppressor gene, is a phosphoprotein that negatively regulates phosphatidylinositol 3'-kinase signaling downstream of Akt. Several high stringency 14-3-3 binding sites that overlapped with Akt phosphorylation sites were identified in tuberin in silico. Recognition of tuberin by an alpha-14-3-3 binding site-specific antibody correlated with mitogen-induced phosphorylation of tuberin and recognition of tuberin by an alpha-Akt phosphorylation substrate antibody. Recognition of tuberin by both antibodies was blocked by inhibiting phosphatidylinositol 3'-kinase activity. Using a protein domain microarray, a tuberin peptide containing Ser(939) demonstrated phospho-specific binding to 14-3-3. Glutathione S-transferase pull-down assays with 14-3-3 fusion proteins revealed that all seven 14-3-3 isoforms (beta, gamma, zeta, epsilon, tau, eta, and sigma) could bind tuberin, and this interaction was abrogated by competition with phosphorylated but not unphosphorylated Ser(939) tuberin peptide. Tuberin also coimmunoprecipitated with 14-3-3, confirming the interaction between endogenous 14-3-3 and tuberin. These data establish the presence of functional and overlapping 14-3-3 and Akt recognition site(s) in tuberin.

14-3-3 Proteins↗

Cell microarrays: an emerging technology for the characterization of antibodies.

The possibility to miniaturize and parallelize biological assays has a great impact on the development of biomedical technologies. Here, we describe a simple, miniaturized, and parallelized method employing entire cells from different cell lines displaying a protein of interest on their surface, which were immobilized on a microarray slide. Antibodies were added to these cellular microarrays, and their specific binding to the cell surface proteins was monitored using appropriate fluorescently labeled detection molecules. This new method is applicable for rapidly screening cell surface-specific antibodies with respect to selectivity and cross-reactivity.

Animals↗

Investigation of selective protein immobilization on charged protein array by wavelength interrogation-based SPR sensor.

We have investigated the use of multilayer films of polyelectrolytes as selective surfaces to analyze protein interactions with a self-assembled SPR wavelength-shift sensor. Charged arrays were prepared by alternating adsorption of the charged polyelectrolytes, poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS). Multilayer formation was monitored with the SPR wavelength-shift sensor and a Spreeta SPR sensor. Protein immobilization on the charged surfaces, which was also analyzed by the SPR sensors, was dependent on the pI of the proteins. Tissue transglutaminase (tTGase) and beta-galactosidase (pIs, 5.1 and 5.3, respectively) were preferentially bound to the positively charged PDDA surface, whereas lysozyme (pI, 11.0) was selectively bound to the negatively charged PSS surface. Immobilization of tTGase on the PDDA surface was also dependent on the buffer pH. The interaction of tTGase with RhoA(V14), a constitutively active form of Rho, could be detected on the charged arrays with the wavelength-shift sensor. The arrays could be reutilized at least 5 times. Thus, it is likely that charged surfaces, assembled by the layer-by-layer method using polyelectrolytes, will prove useful for preparing selective protein arrays.

Adsorption↗

[Structuring of recognizing elements of biosensors. Genetic constructs for the directed immobilization and combination of recognizing and signal generating structures].

Data about the genetic-engineering approaches for providing of directed immobilisation of biological molecules on the transducer surface and for indirect revealing the formed specific complexes are analysed in this review. Creation of nanostructures on the transducer surface and a possibility to do directed transfer of biological molecules from one surface on the other one are considered as well.

Biosensing Techniques↗

Profiling of normal human leg lymph proteins using the 2-D electrophoresis and SELDI-TOF mass spectrophotometry approach.

The parenchymatous cells are supplied by nutrients transported in fluid from blood across the capillary wall. This fluid, called tissue fluid (TF), contains proteins originating from plasma as well as those synthesized and secreted by tissue cells. The protein composition of TF remains largely unknown. The TF which has entered lymphatics is called lymph (L). Harvesting L and measuring its proteins concentrations and identifying them provide an insight into biochemical processes in the TF. Here we describe our initial evaluation of the normal human prenodal L protein profile of m.w. 2.5 to 12.5 kDa using the ProteinChip SELDI MS system and compare it with that of plasma (P) protein. This is the first study in the literature providing evidence for the presence of the so far non-identified proteins in L as well as proteins identified in L but absent from P and conversely present in P but not in L. Evident differences between paired L and P samples have been found, along with similarities. Thirteen proteins were detected in P and seven in L in the region of 2.5 to 12.5 kDa. Five identical proteins, although of different relative intensity, were found in L and P. The proteins specific for L but not P had 7070 and 8619 ion values. P proteins absent from L were of 3890, 3969, 4078, 6863, 7676, 7778, 7847 and 7937 ion values. In addition to detecting some so far unknown proteins in L, these preliminary findings throw a new light on our understanding of the mechanism of transcapillary transport of low m.w. proteins. They challenge the commonly accepted notion of unlimited free diffusion of peptides across the capillary membrane.

Adult↗

[Protein chip].

Explore the source record for details and available documents.

Genomics↗

[Proteomics technology for screening biomarkers of oligospermic candidates].

OBJECTIVE: To screening specific biomarkers of oligospermic candidates from seminal plasma by proteomics technology. METHODS: The protein spectra of 20 seminal plasma from oligospermic patients and healthy male individuals were analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to compare different protein expressions. RESULTS: Compared with normal control group, a specific protein peak of molecular weight 11 022.9 in the protein spectra of oligospermic patients'semen on H4 protein-chip reduced significantly, but the protein peak of molecular weight 11 507.4 elevated apparently. For SAX-2 protein-chip, a specific protein peak of molecular weight 16 751.6 in the protein spectra of oligospermic patients' semen elevated significantly. CONCLUSION: Screening specific proteins in seminal plasma of oligospermic patients is important for understanding the mechanism of oligospermia and screening suspected oligospermic individuals.

Adult↗

Functional protein arrays to facilitate drug discovery and development.

Protein microarrays are miniaturized formats for studying proteins. This technology is empowering investigators with the ability to profile numerous types of interactions to progress basic science research and to advance drug discovery and development. Protein microarrays are poised to make significant contributions to our understanding of biology and disease because: (i) both covalent and non-covalent interactions can be reconstituted on solid-state supports; and (ii) a wealth of knowledge can be generated rapidly from such simple experiments. This feature focuses on applications of protein microarrays that have tremendous potential for addressing bottlenecks in disease-focused discovery efforts.

Animals↗

Morphoproteomic and molecular concomitants of an overexpressed and activated mTOR pathway in renal cell carcinomas.

CCI-779 (temsirolimus), an ester of rapamycin and an inhibitor of the mammalian target of rapamycin (mTOR), is currently in phase II trials for treatment of patients with solid cancers. The mTOR functions as a checkpoint for cell proliferation, with upstream Akt and downstream p70S6K serving as its most important mediators. The aim of this study was to evaluate the expression and activation of the Akt-mTOR-p70S6K pathway in renal cell carcinoma (RCC), seeking to strengthen the rationale for targeted therapy of RCC using rapamycin or a rapamycin analogue. Tissue microarray sections containing 128 primary RCCs, 22 metastatic RCCs, and 24 non-neoplastic (normal) kidneys (NK) were immunostained with monoclonal antibodies to phosphorylated (p)-Akt (Ser473), p-mTOR (Ser2448), and p-p70S6K (Thr389). Western blotting was performed on 3 cases of clear cell RCC (CRCC) and the corresponding non-neoplastic (normal) renal tissues using the same antibodies. The immunostain scoring system included: (a) location; (b) distribution; and (c) intensity. The normal kidneys provided baseline scores for comparison. Expression of p-Akt, p-mTOR, and p-p70S6K was seen in 100% (n = 24) of NKs and nearly 100% (n = 150) of both primary and metastatic RCCs. The p-p70S6K was located in the nucleus in both NKs and RCCs. The p-Akt was observed in the nucleus and cytoplasm of NKs and in the nucleus and cytoplasm/ membrane (plasmalemma) of RCCs. The p-mTOR was identified in the membrane of NKs and the membrane/nucleus of RCCs. The levels of expression of p-p70S6K, p-mTOR, and p-Akt were significantly higher in RCC than in NK in the overall pattern (intensity and distribution, p <0.05). Western blotting also showed higher expression of p-p70S6K, p-mTOR, and p-Akt in RCCs compared to the corresponding normal kidney tissues (p <0.05). These findings indicate that correlative over-expression and activation of p-Akt, p-mTOR, and p-p70S6K are commonly observed in RCCs. After considering these findings in the context of other established protein circuitries and pathways in RCC, we propose therapeutic approaches that incorporate rapamycin-like agents and other small molecule inhibitors in a combinatorial fashion in future clinical trials for RCC.

Antineoplastic Agents↗

[Establishment of protein expression profile of human normal colonic epithelia].

OBJECTIVE: To establish a protein expression profile of human normal colonic epithelia. METHODS: Two-dimensional gel electrophoresis (2-DE) was applied to separate the total proteins of 20 human normal colonic epithelial tissues. The expression proteins in the human normal colonic epithelia were identified by both matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization tandem mass spectrometry (ESI-Q-TOF), and the biological function and subcellular locations of the identified proteins were analyzed by bioinformatics. RESULTS: A 2-DE reference map of human normal colonic epithelium was established. On the 2-DE map, 1020+/-50 protein spots were detected, 204 protein spots representing 162 non-redundant proteins were identified, and 37 proteins had posttranslational modification. The identified proteins were categorized into several protein groups according to their functions or subcellular locations, whose data were available at our website (http://www.xyproteomics.org). CONCLUSION: A protein expression profile of human normal colonic epithelia is established for the first time, which provides useful information for investigating the physiological functions and pathologic process of colonic epithelia.

Adult↗

Region-specific alterations of global protein expression in the remodelled rat myocardium.

We applied the novel ProteinChip technology (SELDI-MS) to investigate and identify differentially regulated proteins upon myocardial remodelling in different heart regions. Tissue samples were isolated from the atria, the interventricular septum, and the right and left ventricles three months after surgically-induced myocardial infarction (MI) in rats. Corresponding protein extracts from control versus MI hearts were analysed on two different ProteinChip surfaces. In each of the functionally distinct cardiac regions, we obtained specific protein profile alterations upon myocardial remodelling. Most alterations were observed in the non-infarcted right ventricle, where down-regulation occurred more frequently than up-regulation of protein expression. Three of the differentially regulated proteins were identified: the metabolic enzyme triosephosphate isomerase (TIM), the cell signalling protein Raf-1 kinase inhibitory protein (RKIP), also known as phosphatidylethanolamine binding protein (PEBP), and the small heat shock protein alphaB-crystallin. These proteins showed a pronounced tissue-dependent regulation. TIM was down-regulated only in the atrium and in the left ventricle, RKIP/PEBP was down-regulated only in the right ventricle and in the interventricular septum, and alphaB-crystallin was up-regulated only in the right and in the left ventricle. A simple correlation of peak intensity changes using two of the identified peaks demonstrated the diagnostic potential of SELDI-MS. We conclude that this novel proteomic method is a powerful high-throughput tool for the fast detection of region-specific cardiac protein profiles in small biopsy samples, and that SELDI-MS may become a useful complementary technique for the diagnosis and prognosis of cardiac diseases.

Animals↗