Project description:The hepatic endoplasmic reticulum contains a series of enzymes that oxidize and conjugate lipid and steroids. Together, these enzymes form a molecular machine that plays key roles in the metabolism of both endogenous and xenobiotic compounds. To characterize this molecular machine, we used quantitative proteomics to assess the frequency of occurrence of detected peptides within each primary sequence, leading to the assessment of the relative abundances of 137 of these proteins. These 137 proteins include over 38 different cytochrome P450s, 11 glucuronosyltransferases, and 9 carboxylesterases. Our sensitive approach was able to detect P450 allelic isoforms which differ by only a single amino acid and clearly resolved 4 splice variants of the glucuronosyltransferases. We identified a cytosolically-exposed DID motif for 3 cytochrome P450s that were located with high abundance in the Golgi apparatus as well the lack of a C-terminal HXEL motif for the sole carboxylesterase highly abundant in the Golgi. Using gene expression microarrays, we also characterized the hepatic transcriptome, and a comparison of proteomics and transcriptomics indicated a requirement for both technologies in order to provide insight into protein families of drug detoxification. In this way, a major hurdle of hepatotoxicity related to drug development may be overcome. Experiment Overall Design: Four replicate Sprague-Dawley rats were assessed, each on an individual microarray.
Project description:<p>The NeuroLINCS Center is part of the NIH Common Fund's Library of Integrated Network-based Cellular Signatures (LINCS) program, which aims to characterize how a variety of human cells, tissues and the entire organism respond to perturbations by drugs and other molecular factors.</p> <p>As Part of the LINCS program, the NeuroLINCS study concentrates on human brain cells, which are far less understood than other cells in the body. Our initial focus is to produce diseased motor neurons from patients by utilizing high-quality induced pluripotent stem cell (iPSC) lines from Amyotrophic Lateral Sclerosis (ALS) and Spinal Muscular Atrophy (SMA) patients in addition to unaffected normal healthy controls. Using state-of-the-art OMICS methods (genomics, epigenomics, transcriptomics, and proteomics), we intend to create a wealth of cellular data that is patient-specific in the context of their baseline genetic perturbations and in the presence of other genetic and environmental perturbagens (e.g. endoplasmic reticulum stress). The primary data will be used to build cell signatures that convey the key features that distinguish the state of a cell and determine its behavior. Ultimately, the analysis of these datasets will lead to the identification of a network of unique signatures relevant to each of these motor neuron diseases. The datasets represented in this study are generated from assays interrogating RNA expression (RNA-seq), chromatin accessibility (ATAC-seq) and whole genome sequencing. </p>
Project description:The hepatic endoplasmic reticulum contains a series of enzymes that oxidize and conjugate lipid and steroids. Together, these enzymes form a molecular machine that plays key roles in the metabolism of both endogenous and xenobiotic compounds. To characterize this molecular machine, we used quantitative proteomics to assess the frequency of occurrence of detected peptides within each primary sequence, leading to the assessment of the relative abundances of 137 of these proteins. These 137 proteins include over 38 different cytochrome P450s, 11 glucuronosyltransferases, and 9 carboxylesterases. Our sensitive approach was able to detect P450 allelic isoforms which differ by only a single amino acid and clearly resolved 4 splice variants of the glucuronosyltransferases. We identified a cytosolically-exposed DID motif for 3 cytochrome P450s that were located with high abundance in the Golgi apparatus as well the lack of a C-terminal HXEL motif for the sole carboxylesterase highly abundant in the Golgi. Using gene expression microarrays, we also characterized the hepatic transcriptome, and a comparison of proteomics and transcriptomics indicated a requirement for both technologies in order to provide insight into protein families of drug detoxification. In this way, a major hurdle of hepatotoxicity related to drug development may be overcome. Keywords: steady-state mRNA levels
Project description:In eukaryotes, up to one-third of cellular proteins are targeted to the endoplasmic reticulum, where they undergo folding, processing, sorting and trafficking to subsequent endomembrane compartments. Targeting to the endoplasmic reticulum has been shown to occur co-translationally by the signal recognition particle (SRP) pathway or post-translationally by the mammalian transmembrane recognition complex of 40 kDa (TRC40) and homologous yeast guided entry of tail-anchored proteins (GET) pathways. Despite the range of proteins that can be catered for by these two pathways, many proteins are still known to be independent of both SRP and GET, so there seems to be a critical need for an additional dedicated pathway for endoplasmic reticulum relay. We set out to uncover additional targeting proteins using unbiased high-content screening approaches. To this end, we performed a systematic visual screen using the yeast Saccharomyces cerevisiae, and uncovered three uncharacterized proteins whose loss affected targeting. We suggest that these proteins work together and demonstrate that they function in parallel with SRP and GET to target a broad range of substrates to the endoplasmic reticulum. The three proteins, which we name Snd1, Snd2 and Snd3 (for SRP-independent targeting), can synthetically compensate for the loss of both the SRP and GET pathways, and act as a backup targeting system. This explains why it has previously been difficult to demonstrate complete loss of targeting for some substrates. Our discovery thus puts in place an essential piece of the endoplasmic reticulum targeting puzzle, highlighting how the targeting apparatus of the eukaryotic cell is robust, interlinked and flexible.
Project description:Modern omics technologies allow us obtaining global information on different types of biological networks. However, integrating these different types of analyzes into a coherent framework for a comprehensive biological interpretation remains challenging. Here, we present a conceptual framework that integrates protein interaction, phosphoproteomics and transcriptomics data. Applying this method to analyze HRAS signaling from different subcellular compartments shows that spatially-defined networks contribute specific functions to HRAS signaling. Changes in HRAS protein interactions at different sites lead to different kinase activation patterns that differentially regulate gene transcription. HRAS mediated signaling is the strongest from the plasma membrane, but it regulates the largest number of genes from the endoplasmic reticulum. The integrated networks provide a topologically and functionally resolved view of HRAS signaling. They reveal new HRAS functions including the control of cell migration from the endoplasmic reticulum and p53 dependent cell survival when signaling from the Golgi apparatus.
Project description:The unfolded protein response (UPR) maintains endoplasmic reticulum (ER) proteostasis through the activation of transcription factors such as XBP1s and ATF6. The functional consequences of these transcription factors for ER proteostasis remain poorly defined. Here, we describe methodology that enables orthogonal, small molecule-mediated activation of the UPR-associated transcription factors XBP1s and/or ATF6 in the same cell independent of stress. We employ transcriptomics and quantitative proteomics to evaluate ER proteostasis network remodeling owing to the XBP1s and/or ATF6 transcriptional programs. Furthermore, we demonstrate that the three ER proteostasis environments accessible by activating XBP1s and/or ATF6 differentially influence the folding, trafficking, and degradation of destabilized ER client proteins without globally affecting the endogenous proteome. Our data reveal how the ER proteostasis network is remodeled by the XBP1s and/or ATF6 transcriptional programs at the molecular level and demonstrate the potential for selectively restoring aberrant ER proteostasis of pathologic, destabilized proteins through arm-selective UPR-activation. The unfolded protein response adapts endoplasmic reticulum (ER) proteostasis via stress-responsive transcription factors including XBP1s and ATF6. Here, R. Luke Wiseman and colleagues implement technology for the orthogonal, ligand-dependent activation of XBP1s and/or ATF6 in a single cell. They characterize how XBP1s and/or ATF6 activation impacts ER proteostasis pathway composition and function. Adapted ER environments influence the proteostasis of destabilized protein variants without affecting the endogenous proteome. The work informs the development of proteostasis environment-adapting therapeutics for protein misfolding-related diseases. In order to activate both XBP1s and ATF6 in the same cell, we incorporated DHFR.ATF6 and tet-inducible XBP1s into a HEK293T-REx cell line stably expressing the tet-repressor. The HEK293DYG control cell line expresses tet-inducible eGFP and DHFR.YFP and is used as a control to demonstrate that the addition of doxycycline (dox) and trimethoprim (TMP) do not induce UPR genes. HEK293DYG cells were treated for 12 h with vehicle or 1 μg/mL dox and 10 μM TMP in biological triplicate. Cells were harvested and RNA was extracted using the RNeasy Mini Kit (Qiagen). Genomic DNA was removed by on-column digestion using the RNase-free DNase Set (Qiagen). Data from HEK293DYG cells showed no significant overlap in the ligand-treated transcriptomes obtained from HEK293DAX cells.
Project description:Background: Metabolic dysregulation has been implicated in bronchopulmonary dysplasia development. Taurine is an essential amino acid for neonates and is critically involved in glucose and fatty acid metabolism. Neonatal tissue obtains taurine mainly through the taurine transporter. The biological role of taurine in neonatal lung development has never been explored. As glucose metabolism mechanistically modulates angiogenesis and angiogenesis is the central player for neonatal lung development, we hypothesize that taurine depletion contributes to bronchopulmonary dysplasia development. Results: Although most genes and proteins for oxidative phosphorylation were enriched in hyperoxia pup lungs, the complex-1 activity decreased. The decrease in taurine-dependent complex-1 core subunits, ND5 and ND6, in hyperoxia lungs reasonably explained the discrepancy. Metabolomics analysis demonstrated decreased lung taurine with increased blood taurine of hyperoxia pups, compatible with the decreased taurine transporter expression. Decreased glycosylation and increased degradation explained the decreased taurine transporter expression. The results of the complementary study using tunicamycin and tauroursodeoxycholic acid studies supported that endoplasmic reticulum stress contributes to decreased taurine transporter expression in hyperoxia lungs. The effect of taurine treatment on reducing endoplasmic reticulum stress, increasing ND5 and ND6 expression, angiogenesis, and, most importantly, the alveolar formation is beneficial to hyperoxia rat pups. Conclusion: Hyperoxia exposure causes endoplasmic reticulum stress, increases taurine transporter degradation, and leads to taurine depletion in the neonatal lungs with subsequent metabolic dysregulation, resulting in poor alveolar formation of the neonatal lungs. We provide evidence of the never-being-reported protective role of taurine in neonatal lung development. The fact that taurine attenuates the severity of bronchopulmonary dysplasia by reducing hyperoxia-induced endoplasmic reticulum stress and mitochondrial dysfunction indicates its therapeutic potential for treating bronchopulmonary dysplasia.
Project description:Mollusk secretes a periostracum layer prior to the underlying calcified shell. This organic membrane serves as the first line of protection and primary template for shell orchestration. However, the chemical composition and formation mechanism of the periostracum layer is largely unknown. In this study, we applied transcriptomic, proteomics, physical and chemical analysis to unravel the mysteries of the periostracum formation in the green mussel Perna viridis (Linnaeus). Scanning electron microscopy examination and FTIR analysis showed that the periostracum layer was a multilayered organic membrane composed of polysaccharides, lipids and proteins. Interestingly, proteomic study identified components enriched in tyrosine and some enzymes evolved in tyrosine oxidation, indicating that tyrosine oxidation might play an important role in the periostracum formation. Moreover, comparative transcriptomics suggested that tyrosine-rich proteins were intensively synthesize in the periostracum groove. After being secreted, the periostracum proteins were gradually tanned by oxidation in the sea water, and the level of crosslink increased significantly as revealed by the ATR-FTIR. Our present study sheds light on the chemical composition and putative tanning mechanism of the periostracum layer in bivalve mollusk.