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PubMed2005

Targets of microRNA regulation in the Drosophila oocyte proteome.

MicroRNAs (miRNAs) are a class of small RNAs that silence gene expression. In animal cells, miRNAs bind to the 3' untranslated regions of specific mRNAs and inhibit their translation. Although some targets of a handful of miRNAs are known, the number and identities of mRNA targets in the genome are uncertain, as are the developmental functions of miRNA regulation. To identify the global range of miRNA-regulated genes during oocyte maturation of Drosophila, we compared the proteome from wild-type oocytes with the proteome from oocytes lacking the dicer-1 gene, which is essential for biogenesis of miRNAs. Most identified proteins appeared to be subject to translation inhibition. Their transcripts contained putative binding sites in the 3' untranslated region for a subset of miRNAs, based on computer modeling. The fraction of genes subject to direct and indirect repression by miRNAs during oocyte maturation appears to be small (4%), and the genes tend to share a common functional relationship in protein biogenesis and turnover. The preponderance of genes that control global protein abundance suggests this process is under tight control by miRNAs at the onset of fertilization.

3' Untranslated Regions↗
PubMed2025

Oncoproteins E6/E7 of the human papillomavirus types 16 & 18 synergize in modulating oncogenes and tumor suppressor proteins in colorectal cancer.

OBJECTIVE: Our study presents a novel analysis of the oncogenes and tumor suppressor proteins directly modulated by E6/E7 of high-risk HPV types 16 and 18, in colorectal cancer (CRC). METHODS: HCT 116 (KRAS mutant) & HT-29 (TP53 mutant) cell models of CRC were transduced with E6/E7 of HPV16 and HPV18, individually and in combination. Further, we utilized a liquid chromatography mass spectrometry (LC-MS/MS) approach to analyze and compare the proteomes of both CRC cell models. RESULTS: We generated six stably transduced cell lines. Our data revealed a significantly higher, HPV-induced modulation of oncogenes and tumor suppressor proteins in the TP53 mutant model, as compared to the KRAS mutant model (p ≤ 0.01). Less than 1% of the genes were commonly modulated by HPV, between both models. We also report that HT-29 cells, expressing E6/E7 of both HPV types, significantly reduced the suppression of oncogenes as compared to cells expressing E6/E7 of either HPV types individually (p-value ≤0.00001). CONCLUSION: Our data imply that HPV coinfections leads to the sustenance of a pro-oncogenic environment in CRC. HPV modulates different oncogenes/tumor suppressor proteins in CRC of varying mutational backgrounds, thus highlighting the importance of personalized therapies for such diseases with mutational heterogeneity.

Humans↗
PubMed2026

Elucidating the In Vitro Adverse Effect of Functionalized Single-Walled Carbon Nanotubes Against Breast Cancer Cells at the Proteomics Level.

The tremendous therapeutic potential of carbon-based nanomaterials (CNMs) has been limited by inconsistent data regarding the nanotoxicity assessment. Although a bulk of studies have been performed to assess the in vitro cytotoxicity mechanism of CNMs, the exact factors responsible for the cytotoxicity of CNMs have not been fully understood. With the rapid advancement of mass spectrometry technologies, proteomics has emerged as a powerful strategy for systematically investigating the molecular and cellular mechanisms underlying toxicity induced by nanomaterials. This study examined the in vitro cytotoxicity of single-walled carbon nanotubes (SWCNTs) in human MCF-7 breast cancer cells by conducting a comparative proteome-level analysis using mass spectrometry. Initially, the characterized SWCNTs were incubated with MCF-7 cells for 3, 6, and 24 h. Proteins were subsequently extracted from each treatment group and subjected to nano-liquid chromatography-tandem mass spectrometry (nLC-MS/MS) analysis. The relative abundance of the identified proteins was determined by comparison with the control group, and differential expression patterns, including upregulated and downregulated proteins, were assessed. A total of 3482 unique protein groups were identified across all exposure periods. Among these, 3466 protein groups were detected following 3 h of exposure, 3469 following 6 h of exposure, and 3480 following 24 h of exposure. Compared with the control group, the identified differentially expressed proteins exhibited fold changes ranging from 2-fold to 20-fold across the incubation periods. In total, 70 proteins were found to be significantly regulated following SWCNT exposure. Of the differentially expressed proteins, 45 were significantly upregulated, whereas 25 were significantly downregulated. Visualization of these regulations over time was shown in a heatmap of log2-transformed fold-change values to explore time-specific proteomic alterations. Functional enrichment analysis of these proteins also showed that the regulated proteins were significantly associated with Reactome pathways, including ER-to-Golgi anterograde transport, Golgi-to-ER retrograde transport, COPI-mediated vesicle trafficking, regulation of insulin-like growth factor transport and uptake by insulin-like growth factor-binding proteins, protein metabolism, and posttranslational protein modification. Furthermore, a systematic comparison of previous studies within the present findings was provided to situate our study within the broader context of understanding CNT-induced cellular toxicity. Collectively, these findings provided an important proteomic evidence of the adverse effects of SWCNTs on MCF-7 cells. Furthermore, this study showed a comprehensive proteomic landscape of cellular responses to SWCNT exposure, contributing to a better understanding of the molecular mechanisms underlying SWCNT-induced cytotoxicity and bridging the gap between protein regulation and the resulting cellular responses. In this study, we characterized the proteomic landscape of MCF-7 cells following SWCNT exposure, revealing molecular mechanisms associated with cellular responses and cytotoxicity. The identified differentially expressed proteins established a link between altered protein regulation and SWCNT-induced cellular effects. Moreover, these proteins need to be further validated in different cell models and would potentially represent promising candidates for the identification of novel molecular targets involved in SWCNT-induced cytotoxicity.

MCF‐7 cells↗
PubMed2004

Proteome analyses of heme-dependent respiration in Lactococcus lactis: involvement of the proteolytic system.

Sugar fermentation was long considered the sole means of energy metabolism available to lactic acid bacteria. We recently showed that metabolism of Lactococcus lactis shifts progressively from fermentation to respiration during growth when oxygen and heme are available. To provide insights into this phenomenon, we compared the proteomic profiles of L. lactis under fermentative and respiratory growth conditions in rich medium. We identified 21 proteins whose levels differed significantly between these conditions. Two major groups of proteins were distinguished, one involved in carbon metabolism and the second in nitrogen metabolism. Unexpectedly, enzymes of the proteolytic system (PepO1 and PepC) which are repressed in rich medium in fermentation growth were induced under respiratory conditions despite the availability of free amino acids. A triple mutant (dtpT dtpP oppA) deficient in oligopeptide transport displayed normal respiration, showing that increased proteolytic activity is not an absolute requirement for respiratory metabolism. Transcriptional analysis confirmed that pepO1 is induced under respiration-permissive conditions. This induction was independent of CodY, the major regulator of proteolytic functions in L. lactis. We also observed that pepO1 induction is redox sensitive. In a codY mutant, pepO1 expression was increased twofold in aeration and eightfold in respiration-permissive conditions compared to static conditions. These observations suggest that new regulators activate proteolysis in L. lactis, which help to maintain the energetic needs of L. lactis during respiration.

Bacterial Proteins↗
PubMed2004

Differential protein synthesis and expression levels in normal and neoplastic human prostate cells and their regulation by type I and II interferons.

Protein expression and de novo synthesis in normal and prostate cancer cell lines derived from the same patient were compared by proteomic analysis, and the effects of INFalpha and INFgamma (INF=interferon) determined. The expressions of several INF-inducible proteins, including MxA, Nmi, PA28a and IFP53, were downregulated in the cancer cells. INFgamma induced a more than twofold increase or decrease in the synthesis rates of almost twice as many proteins in the cancer cell line. The positive regulator of INF-induced transcription ISGF3gamma was upregulated in the cancer cells and inversely regulated by INFalpha and INFgamma in the normal and cancer cells. Moreover, ISGF3gamma's induction by INFgamma in the cancer cells was more enhanced by simultaneous stimulation with EGF, than its induction in the normal cells. In all, 31 differentially regulated proteins were identified by mass spectrometry analysis, several of which are involved in chaperone-assisted protein folding in the endoplasmic reticulum (ER) or in regulated protein degradation. Our results suggest that the exclusion of proteins by the ER quality control system, crosstalk between the EGF- and INF-induced signalling pathways and the regulation of INF-inducible genes are all altered in the prostate cancer cells. The combination of upregulated activity in the growth-promoting PI3K/Akt pathway, suppression of Nmi and overexpression of hnRNP-K and c-myc proteins may explain why the prostate cancer cells were found to be more resistant to the growth inhibitory effects of INFgamma.

Carrier Proteins↗
PubMed2026

Proteomic insights into azoospermia: protein differences in testicular tissue between non-obstructive and obstructive azoospermia patients.

Non-obstructive azoospermia (NOA) and obstructive azoospermia (OA) are the main classifications of severe male infertility, but the molecular mechanism of NOA remains poorly understood. This study aimed to identify potential biomarkers and pathological mechanisms by comparing the proteomic differences in testicular tissues of NOA and OA patients. Through proteomic analysis based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) of testicular samples from 5 NOA patients and 5 OA patients, we identified 5264 proteins, among which 717 differentially expressed proteins (DEPs) were found between the two groups (242 upregulated and 475 downregulated in NOA). Bioinformatics analysis indicated that these DEPs were significantly associated with reproductive development, gametogenesis, and cell structural stability. On the basis of this, six candidate proteins, including dysferlin (DYSF), myoferlin (MYOF), mitsugumin 53 (MG53), cluster of differentiation 63 (CD63), caveolin-3 (CAV3), and calpain-3 (CAPN3), were selected from the DEPs and verified in an expanded sample set (37 NOA cases and 28 OA cases) through quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot, confirming their dysregulation in NOA. These findings provide new proteomic insights into NOA, highlighting the disruption of membrane repair and structural pathways, and offer potential biomarkers for understanding its pathogenesis.

Humans↗
PubMed2002

Identification of the phosphotyrosine proteome from thrombin activated platelets.

Signalling cascades are regulated both positively and negatively by tyrosine phosphorylation. Integrin mediated platelet adhesion triggers signal transduction cascades involving translocation of proteins and tyrosine phosphorylation events, ultimately causing large signalling complexes to be assembled. In resting platelets, a small number of phosphorylated proteins are evident with molecular mass of 50-62 kDa and 120-130 kDa. In thrombin activated human platelets, however, there is a large increase in the number of tyrosine phosphorylated signalling proteins detected. These proteins include pCas (130 kDa), FAK (125 kDa), PI(3)k (85 kDa) and src (85 kDa). However, it is unlikely that this list of proteins represents all the dynamic changes that occur after platelet activation and it is understood that more proteins remain unidentified. In this study, we propose a method for the isolation of the phosphotyrosine proteome from both resting and thrombin activated human platelets. All the dynamic phosphotyrosine events that occur in the platelet after thrombin activation were isolated by immunoprecipitation, using the monoclonal antibody 4G10, allowing us to obtain higher concentrations of relatively low abundant proteins. The resulting phosphotyrosine proteomes were separated by two-dimensional gel electrophoresis. Sixty-seven proteins were reproducibly found to be unique in the thrombin activated platelet proteome when compared to resting platelets. We have positively identified ten of these proteins by Western blotting and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry and these include FAK, Syk, ALK-4, P2X6 and MAPK kinase kinase. This proteomics approach to understanding the signalling events following platelet activation may elucidate potential drug targets for the treatment of coronary thrombosis.

Blood Platelets↗
PubMedDate not supplied

Proteome analysis of tobacco bright yellow-2 (BY-2) cell culture plastids as a model for undifferentiated heterotrophic plastids.

We analyzed the proteome of undifferentiated plastids from a tobacco BY-2 cell culture by shotgun proteomics following multidimensional protein fractionation. The fractionation strategy initiated with the serial extraction of proteins from membranes which allowed us to distinguish soluble, peripheral, and integral membrane proteins. The majority of the identified proteins have a function in the cellular metabolism and most of them are active in amino acid synthesis pathways. A significant number of the identified proteins was not identified in chloroplast proteome analyses before. This suggests BY-2 plastid specific functions that differ from the major activities of chloroplasts. We have used the BY-2 plastid proteins reported here to assess the metabolic activities of undifferentiated heterotrophic plastids and compared the functional profile with that of differentiated heterotrophic amyloplasts. Comparative shotgun proteome analyses as reported here provide information about prevalent metabolic activities of different plastid types.

Cell Differentiation↗
PubMed2006

Identification of differential proteins in nasopharyngeal carcinoma cells with p53 silence by proteome analysis.

Although mutation of p53 tumor-suppressor gene is rare in nasopharyngeal carcinoma (NPC), NPC has a high frequency of overexpression of p53 protein. There seem to be complex mechanisms of inactivation and stabilization of p53 in NPC. To detect proteins associated with the function of p53 in high throughout screening, we succeeded in establishing p53 knockdown human NPC CNE2 cell line (CNE2sip53) using stable RNA interference, and compared the proteomic changes between CNE2sip53 and control cell line CNE2/pSUPER using two-dimensional gel electrophoresis. Twenty-two differentially expressed proteins between the two cell lines were identified by both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization tandem mass spectrometry, some of which are known to be associated with the p53 function (HSP27, hnRNP K, 14-3-3sigma, etc.), and others may be novel proteins associated with p53 function (eIF4B, TPT1, hnRNP H3, SFRS1 etc.). Furthermore, several differential proteins including HSP27, HSP70, GRP75 and GRP78 were verified as p53 interacting proteins in NPC by immunoprecipitation and Western blot analysis, and the suppression of HSP27 expression by HSP27 antisense oligonucleotides could decrease the p53 protein level. Our data suggest that these differential proteins may be associated with the function of p53 in NPC, and provide new clues to elucidate the mechanisms of inactivation and stabilization of p53 in NPC.

Cell Line, Tumor↗
PubMed2006

Multidimensional capillary array liquid chromatography and matrix-assisted laser desorption/ionization tandem mass spectrometry for high-throughput proteomic analysis.

A two-dimensional capillary array liquid chromatography system coupled with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) was developed for high-throughput comprehensive proteomic analysis, in which one strong cation-exchange (SCX) capillary chromatographic column was used as the first separation dimension and 10 parallel reversed-phase liquid chromatographic (RPLC) capillary columns were used as the second separation dimension. A novel multi-channel interface was designed and fabricated for on-line coupling of the SCX to RPLC column array system. Besides the high resolution based on the combination of SCX and RPLC separation, the developed new system provided the most rapid two-dimensional liquid chromatography (2D-LC) separation. Ten three-way micro-splitter valves used as stop-and-flow switches in transferring SCX fractions onto RPLC columns. In addition, the three-way valves also acted as mixing chambers of RPLC effluent with matrix. The system enables on-line mixing of the LC array effluents with matrix solution during the elution and directly depositing the analyte/matrix mixtures on MALDI plates from the tenplexed channels in parallel through an array of capillary tips. With the novel system, thousands of peptides were well separated and deposited on MALDI plates only in 150min for a complex proteome sample. Compared with common 2D-LC system, the parallel 2D-LC system showed about 10-times faster analytical procedure. In combination with a high throughput tandem time of flight mass spectrometry, the system was proven to be very effective for proteome analysis by analyzing a complicated sample, soluble proteins extracted from a liver cancer tissue, in which over 1202 proteins were identified.

Chromatography, Liquid↗
PubMed2003

A comparative analysis of an orthologous proteomic environment in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe.

The sequential application of protein tagging, affinity purification, and mass spectrometry enables highly accurate charting of proteomic environments by the characterization of stable protein assemblies and the identification of subunits that are shared between two or more protein complexes, termed here "proteomic hyperlinks." We have charted the proteomic environments surrounding the histone methyltransferase, Set1, in both yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. Although the composition of these nonessential Set1 complexes is remarkably conserved, they differ with respect to their hyperlinks to their proteomic environments. We speculate that conservation of the core components of protein assemblies and variability of hyperlinks represents a general principle in the molecular organization of eukaryotic proteomes.

DNA-Binding Proteins↗
PubMed2026

Proteomic Analysis of Three Independent Series of Sequential Cystic Fibrosis Strains in an International Pseudomonas aeruginosa Reference Panel Indicates Positive Selection in Late Infection Strains.

Pseudomonas aeruginosa is a highly diverse, adaptable Gram-negative bacterium that thrives in many environments and is a frequent cause of chronic opportunistic infections in people with cystic fibrosis (CF). P. aeruginosa adapts over time of colonization to facilitate chronic infection, including loss of virulence factors; however, proteomic analyses of the adaptation to chronic infection have been limited. We previously assembled and characterized an international panel of P. aeruginosa strains from diverse clinical and geographical sources, including three sets of sequential CF isolates, enabling identification of conserved adaptations linked to chronic CF lung colonization. We compared the proteomes of eight strains (three early and five late infection) to assess whether common proteomic changes emerged during colonization across the sequential isolates. We identified 11 proteins showing increased abundance in late isolates in all three series, many of which are associated with virulence, regulation of virulence, or response to hypoxia. These include CF inhibitory factor repressor (CifR); WspR; 2 two-component response regulators (PA2572 and PA3702), and transcriptional regulator (PA2551). Moreover, we identified three proteins (PA2572, PA3819, and PA5028) that showed increased abundance in all five late isolates. The probability of this being random is 5.06 × 10-53 and therefore, strong evidence of positive selection. The increased abundance of PA2573 and PA3819 appears to improve the fitness of P. aeruginosa in response to antibiotics and oxidative stress. All three proteins share a tyrosine phosphorylation motif, suggesting a common regulatory mechanism. Overall, despite substantial diversity across P. aeruginosa, common adaptations occur in the CF lung.

Pseudomonas aeruginosa↗
PubMed2005

Effects of growth phase and the developmentally significant bldA-specified tRNA on the membrane-associated proteome of Streptomyces coelicolor.

Previous proteomic analyses of Streptomyces coelicolor by two-dimensional electrophoresis and protein mass fingerprinting focused on extracts from total cellular material. Here, the membrane-associated proteome of cultures grown in a liquid minimal medium was partially characterized. The products of some 120 genes were characterized from the membrane fraction, with 70 predicted to possess at least one transmembrane helix. A notably high proportion of ABC transporter systems was represented; the specific types detected provided a snapshot of the nutritional requirements of the mycelium. The membrane-associated proteins did not change very much in abundance in different phases of growth in liquid minimal medium. Identification of gene products not expected to be present in membrane protein extracts led to a reconsideration of the genome annotation in two cases, and supplemented scarce information on 11 hypothetical/conserved hypothetical proteins of unknown function. The wild-type membrane proteome was compared with that of a bldA mutant lacking the only tRNA capable of efficient translation of the rare UUA (leucine) codon. Such mutants are unaffected in vegetative growth but are defective in many aspects of secondary metabolism and morphological differentiation. There were a few clear changes in the membrane proteome of the mutant. In particular, two hypothetical proteins (SCO4244 and SCO4252) were completely absent from the bldA mutant, and this was associated with the TTA-containing regulatory gene SCO4263. Evidence for the control of a cluster of function-unknown genes by the SCO4263 regulator revealed a new aspect of the pleiotropic bldA phenotype.

Base Sequence↗
PubMed2025

Application of Proteomic Methods in Oomycete Biology.

The biochemical makeup of any organism provides insight into key factors regarding its biological functions. These factors can be explored using proteomics, which allows us to obtain a snapshot of the protein content and abundance in an organism, cell type or sub-cellular compartment. Here, we describe proteomic methodologies that can be used to dissect the biochemical mechanism of phytopathogenicity in oomycetes. These methodologies include protein extraction, purification, subsequent processing, mass spectrometry analysis, and qualitative and quantitative data processing of oomycete proteomes for comparative studies. Additionally, the use of mass spectra to assist in gene validation and modelling in unfinished oomycete genomes is also described.

Oomycetes↗
PubMed2006

Proteomic profiling identifies cyclooxygenase-2-independent global proteomic changes by celecoxib in colorectal cancer cells.

Celecoxib, a selective inhibitor of the enzyme cyclooxygenase-2 (COX-2), has been shown to be a promising chemoprevention agent. The chemopreventive efficacy of celecoxib is believed to be a consequence of its COX-2-dependent and COX-2-independent effects on a variety of cellular processes including proliferation, apoptosis, angiogenesis, and immunosurveillance. In an attempt to identify proteomic markers modulated by celecoxib that are independent of its inhibitory effect on COX-2, the colorectal cancer cell line HCT-116, a nonexpresser of COX-2, was treated with celecoxib. We used the powerful, state-of-the-art two-dimensional difference gel electrophoresis technology coupled with mass spectrometric sequencing to compare global proteomic profiles of HCT-116 cells before and after treatment with celecoxib. Among the differentially expressed proteins identified following celecoxib treatment were proteins involved in diverse cellular functions including glycolysis, protein biosynthesis, DNA synthesis, mRNA processing, protein folding, phosphorylation, redox regulation, and molecular chaperon activities. Our study presents a comprehensive analysis of large-scale celecoxib-modulated proteomic alterations, at least some of which may be mechanistically related to the COX-2-independent chemopreventive effect of celecoxib.

Blotting, Western↗
PubMed2004

Proteomic analysis of a ferric uptake regulator mutant of Helicobacter pylori: regulation of Helicobacter pylori gene expression by ferric uptake regulator and iron.

The ferric uptake regulator (Fur) protein is a Fe(2+)-dependent transcriptional repressor that binds to the Fur-box of bacterial promoters and down-regulates gene expression. In this study, to investigate global gene regulation by Fur in response to iron in Helicobacter pylori, a causative agent of human gastric diseases, we compared the proteome profiles of the H. pylori strain 26695 and its isogenic fur mutant grown under iron-rich and iron-depleted conditions. In total, 93 protein spots were found to be up- or down-regulated by more than 2-fold by either a fur mutation or iron-depletion. From these, 39 spots were identified by matrix-assisted laser desorption/ionization time of flight analysis to be 29 different proteins of diverse functions, including energy metabolism, transcription and translation, detoxification, biosynthesis of amino acids and nucleotides and production of the cell envelope. Expression of six proteins was found to be higher in the fur mutant than in the wild-type bacteria, indicating Fur-mediated repression. Eleven proteins were activated by Fur; five responded to iron and the others were not iron-responsive. The remaining 12 proteins were not under Fur-regulation but responded to iron in a positive or negative manner. Seven different types of gene regulation via Fur and iron were identified. These findings demonstrate that the H. pylori Fur protein functions as a classical transcriptional repressor but can also function as an activator, providing evidence for the presence of Fur-mediated positive regulation in H. pylori.

Bacterial Proteins↗
PubMed2003

In silico proteome analysis to facilitate proteomics experiments using mass spectrometry.

Proteomics experiments typically involve protein or peptide separation steps coupled to the identification of many hundreds to thousands of peptides by mass spectrometry. Development of methodology and instrumentation in this field is proceeding rapidly, and effective software is needed to link the different stages of proteomic analysis. We have developed an application, proteogest, written in Perl that generates descriptive and statistical analyses of the biophysical properties of multiple (e.g. thousands) protein sequences submitted by the user, for instance protein sequences inferred from the complete genome sequence of a model organism. The application also carries out in silico proteolytic digestion of the submitted proteomes, or subsets thereof, and the distribution of biophysical properties of the resulting peptides is presented. proteogest is customizable, the user being able to select many options, for instance the cleavage pattern of the digestion treatment or the presence of modifications to specific amino acid residues. We show how proteogest can be used to compare the proteomes and digested proteome products of model organisms, to examine the added complexity generated by modification of residues, and to facilitate the design of proteomics experiments for optimal representation of component proteins.

Journal Article↗
PubMed2002

Proteome analysis of cerebrospinal fluid proteins in Alzheimer patients.

By comparing the CSF proteome between Alzheimer disease (AD) patients and controls it may be possible to identify proteins that play a role in the disease process and thus to study the pathogenesis of AD. We used mini-gel technology in a two-dimensional electrophoresis procedure, sensitive SYPRO Ruby staining and mass spectrometry for clinical screening of disease-influenced CSF proteins in 15 AD patients and 12 controls. The levels of six proteins and their isoforms, including proapolipoprotein, apolipoprotein E, beta-2 microglobulin, retinol-binding protein, transthyretin, and ubiquitin, were significantly altered in CSF of AD patients. The most prominently altered proteins were the apolipoproteins, especially proapolipoprotein.

Aged↗