Mitomycin C and its analog trigger cytotoxicity in MCF-7 and K562 cancer cells through the regulation of RAS and MAPK/ERK pathways

Mitomycin C (MC) is an anti-cancer drug which functions by forming interstrand crosslinks (ICLs) between opposing DNA strands. MC analog, 10-decarbamoyl mitomycin C (DMC), unlike MC, has stronger cytotoxic effects on cancer cells with TP53 mutation. We previously demonstrated that MC/DMC could activate p21WAF1/CIP1 in MCF-7 (TP53-proficient) and K562 (TP53 deficient) cells in a TP53-independent mode. We also found that MC/DMC regulate AKT activation in a TP53-dependent manner and that AKT deactivation is not associated with the activation of p21WAF1/CIP1 in response to MC/DMC treatment. RAS proteins are known players in the upstream mediated signaling of p21WAF1/CIP1 activation that leads to control of cell proliferation and cell death. Thus, this prompted us to investigate the effect of both drugs on the expression of RAS proteins and regulation of the MAPK/ERK signaling pathways in MCF-7 and K562 cancer cells. To accomplish this goal, we performed comparative label free proteomics profiling coupled to bioinformatics/complementary phosphoprotein arrays and Western blot validations of key signaling molecules. The MAPK/ERK pathway exhibited an overall downregulation upon MC/DMC treatment in MCF-7 cells but only DMC exhibited a mild downregulation of that same pathway in TP53 mutant K562 cells. Furthermore, treatment of MCF-7 and K562 cell lines with oligonucleotides containing the interstrand crosslinks (ICLs) formed by MC or DMC shows that both ICLs had a stronger effect on the downregulation of RAS protein expression in mutant TP53 K562 cells. We discuss the implication of this regulation of the MAPK/ERK pathway in relation to cellular TP53 status.

Molecular determinants of the crosstalk between endosomal microautophagy and chaperone-mediated autophagy

Chaperone-mediated autophagy (CMA) and endosomal microautophagy (eMI) are pathways for selective degradation of cytosolic proteins in lysosomes and late endosomes, respectively. These autophagic processes share as a first step the recognition of the same five-amino-acid motif in substrate proteins by the Hsc70 chaperone, raising the possibility of coordinated activity of both pathways. In this work, we show the existence of a compensatory relationship between CMA and eMI and identify a role for the chaperone protein Bag6 in triage and internalization of eMI substrates into late endosomes. Association and dynamics of Bag6 at the late endosome membrane change during starvation, a stressor that, contrary to other autophagic pathways, causes a decline in eMI activity. Collectively, these results show a coordinated function of eMI with CMA, identify the interchangeable subproteome degraded by these pathways, and start to elucidate the molecular mechanisms that facilitate the switch between them.

Senolytic treatment reduces oxidative protein stress in an aging male murine model of post-traumatic osteoarthritis

Senolytic drugs are designed to selectively clear senescent cells (SnCs) that accumulate with injury or aging. In a mouse model of osteoarthritis (OA), senolysis yields a pro-regenerative response, but the therapeutic benefit is reduced in aged mice. Increased oxidative stress is a hallmark of advanced age. Therefore, here we investigate whether senolytic treatment differentially affects joint oxidative load in young and aged animals. We find that senolysis by a p53/MDM2 interaction inhibitor, UBX0101, reduces protein oxidative modification in the aged arthritic knee joint. Mass spectrometry coupled with protein interaction network analysis and biophysical stability prediction of extracted joint proteins revealed divergent responses to senolysis between young and aged animals, broadly suggesting that knee regeneration and cellular stress programs are contrarily poised to respond as a function of age. These opposing responses include differing signatures of protein-by-protein oxidative modification and abundance change, disparate quantitative trends in modified protein network centrality, and contrasting patterns of oxidation-induced folding free energy perturbation between young and old. We develop a composite sensitivity score to identify specific key proteins in the proteomes of aged osteoarthritic joints, thereby nominating prospective therapeutic targets to complement senolytics.

PDIA3 epitope-driven immune autoreactivity contributes to hepatic damage in type 2 diabetes

A diet rich in saturated fat and carbohydrates causes low-grade chronic inflammation in several organs, including the liver, ultimately driving nonalcoholic steatohepatitis. In this setting, environment-driven lipotoxicity and glucotoxicity induce liver damage, which promotes dendritic cell activation and generates a major histocompatibility complex class II (MHC-II) immunopeptidome enriched with peptides derived from proteins involved in cellular metabolism, oxidative phosphorylation, and the stress responses. Here, we demonstrated that lipotoxicity and glucotoxicity, as driven by a high-fat and high-fructose (HFHF) diet, promoted MHC-II presentation of nested T and B cell epitopes from protein disulfide isomerase family A member 3 (PDIA3), which is involved in immunogenic cell death. Increased MHC-II presentation of PDIA3 peptides was associated with antigen-specific proliferation of hepatic CD4⁺ immune infiltrates and isotype switch of anti-PDIA3 antibodies from IgM to IgG3, indicative of cellular and humoral PDIA3 autoreactivity. Passive transfer of PDIA3-specific T cells or PDIA3-specific antibodies also exacerbated hepatocyte death, as determined by increased hepatic transaminases detected in the sera of mice subjected to an HFHF but not control diet. Increased humoral responses to PDIA3 were also observed in patients with chronic inflammatory liver conditions, including autoimmune hepatitis, primary biliary cholangitis, and type 2 diabetes. Together, our data indicated that metabolic insults caused by an HFHF diet elicited liver damage and promoted pathogenic immune autoreactivity driven by T and B cell PDIA3 epitopes.

METABOLIC INSULTS ELICIT EPITOPE-DEPENDENT IMMUNE AUTOREACTIVITY AGGRAVATING HEPATIC DAMAGE IN TYPE 2 DIABETES

A diet rich in saturated fat and carbohydrates causes low-grade chronic inflammation in several organs including the liver, ultimately driving non-alcoholic steatohepatitis. The environment-driven lipotoxicity and glucotoxicity induces liver damage, which promotes dendritic cell adjuvanticity and generates an MHC-II immunopeptidome enriched of peptides derived from proteins involved in cellular metabolism, oxidative phosphorylation, and stress responses. Here, we demonstrate that metabolic insults promote the presentation of nested T and B cell epitopes from protein disulfide isomerase family A member 3 (PDIA3, which is involved in immunogenic cell death) on MHC Class II, ultimately supporting pathogenic autoreactivity. Additionally, PDIA3-driven T cell responses infiltrating the hepatic parenchyma, favored the release of TH1 and TH17 pro-inflammatory cytokines and, PDIA3-driven B cell responses were associated with antibodies that aggravated hepatic toxicity in mice subjected to high-fat and high-sucrose diet. Increased humoral responses to PDIA3 were also observed in patients with chronic inflammatory liver conditions including autoimmune hepatitis, primary biliary cholangitis and type 2 diabetes. Altogether our data indicate that metabolic insult caused by high-sucrose diet, cause tissue damage, which, by supplying PDIA3 T cell and B cell epitopes further contributes to epitope-dependent pathogenic immune autoreactivity

Supported by NIHAI146180 and NIH AI137198

Characterization of a Novel Anti-inflammatory Biogenic Amine

Tryptophan (Trp) is an essential amino acid whose catabolism generates a cascade of over fifty molecules in a cell-specific manner. Three major Trp metabolic pathways have been described: synthesis of serotonin, synthesis of melatonin and generation of kynurenines. In mammalian cells, 90% of Trp is processed through the kynurenine pathway and kynurenine metabolites are regarded as one of the most powerful mechanism for immune regulation. We recently reported a novel biogenic amine, 3HKA, generated through a still uncharacterized lateral pathway of Trp catabolism. This novel biogenic amine is generated by both professional (Dendritic Cells) and non-professional (Lymphatic Endothelial Cells) antigen presenting cells and, differently from all others Trp metabolites, display unique “in vivo” immunosuppressive capabilities. In vitro, 3-HKA exhibited an anti-inflammatory profile by inhibiting the IFN-g-mediated STAT1/NF-kB pathway in both mouse and human dendritic cells (DCs) with a consequent decrease in the release of pro-inflammatory chemokines and cytokines; most notably, TNFa, IL-6, and IL12p70. In vivo, 3-HKA exerted protective effects in an experimental mouse model of Psoriasis by decreasing skin thickness, erythema, scaling and fissuring, reducing TNFa, IL-1b, IFN-g, and IL-17 production, and inhibiting generation of effector CD8+ T cells. Similarly, in a mouse model of nephrotoxic nephritis, besides reducing inflammatory cytokines, 3-HKA improved proteinuria and serum urea nitrogen, overall ameliorating the immune-mediated glomerulonephritis and renal dysfunction. Overall we propose that this novel biological amine is a crucial component of Trp-mediated immune tolerance.

Lung lymphatic thrombosis and dysfunction caused by cigarette smoke exposure precedes emphysema in mice

The lymphatic vasculature is critical for lung function, but defects in lymphatic function in the pathogenesis of lung disease is understudied. In mice, lymphatic dysfunction alone is sufficient to cause lung injury that resembles human emphysema. Whether lymphatic function is disrupted in cigarette smoke (CS)-induced emphysema is unknown. In this study, we investigated the effect of CS on lung lymphatic function. Analysis of human lung tissue revealed significant lung lymphatic thrombosis in patients with emphysema compared to control smokers that increased with disease severity. In a mouse model, CS exposure led to lung lymphatic thrombosis, decreased lymphatic drainage, and impaired leukocyte trafficking that all preceded the development of emphysema. Proteomic analysis demonstrated an increased abundance of coagulation factors in the lymph draining from the lungs of CS-exposed mice compared to control mice. In addition, in vitro assays demonstrated a direct effect of CS on lymphatic endothelial cell integrity. These data show that CS exposure results in lung lymphatic dysfunction and a shift in thoracic lymph towards a prothrombic state. Furthermore, our data suggest that lymphatic dysfunction is due to effects of CS on the lymphatic vasculature that precede emphysema. These studies demonstrate a novel component of CS-induced lung injury that occurs early in the pathogenesis of emphysema.

A protocol for qualitative and quantitative measurement of endosomal processing using hot spot analysis

A detailed quantification of antigen processing by endosomal compartments provides important information on the pattern of protein fragmentation. Here, we describe a protocol that combines gradient purified endosomes, incubated with antigens, followed by hot spot analysis of MS/MS-sequenced peptides. The analysis identifies differences in endosomal antigen processing by dendritic cells under diverse experimental conditions. For complete details on the use and execution of this protocol, please refer to Clement et al. (2021).

Distinguishing Signal From Noise in Immunopeptidome Studies of Limiting-Abundance Biological Samples: Peptides Presented by I-Ab in C57BL/6 Mouse Thymus

Antigen presentation by MHC-II proteins in the thymus is central to selection of CD4 T cells, but analysis of the full repertoire of presented peptides responsible for positive and negative selection is complicated by the low abundance of antigen presenting cells. A key challenge in analysis of limiting abundance immunopeptidomes by mass spectrometry is distinguishing true MHC-binding peptides from co-eluting non-specifically bound peptides present in the mixture eluted from immunoaffinity-purified MHC molecules. Herein we tested several approaches to minimize the impact of non-specific background peptides, including analyzing eluates from isotype-control antibody-conjugated beads, considering only peptides present in nested sets, and using predicted binding motif analysis to identify core epitopes. We evaluated these methods using well-understood human cell line samples, and then applied them to analysis of the I-Ab presented immunopeptidome of the thymus of C57BL/6 mice, comparing this to the more easily characterized splenic B cell and dendritic cell populations. We identified a total of 3473 unique peptides eluted from the various tissues, using a data dependent acquisition strategy with a false-discovery rate of <1%. The immunopeptidomes presented in thymus as compared to splenic B cells and DCs identified shared and tissue-specific epitopes. A broader length distribution was observed for peptides presented in the thymus as compared to splenic B cells or DCs. Detailed analysis of 61 differentially presented peptides indicated a wider distribution of I-Ab binding affinities in thymus as compared to splenic B cells. These results suggest different constraints on antigen processing and presentation pathways in central versus peripheral tissues.

Chaperone-mediated autophagy prevents collapse of the neuronal metastable proteome

Components of the proteostasis network malfunction in aging, and reduced protein quality control in neurons has been proposed to promote neurodegeneration. Here, we investigate the role of chaperone-mediated autophagy (CMA), a selective autophagy shown to degrade neurodegeneration-related proteins, in neuronal proteostasis. Using mouse models with systemic and neuronal-specific CMA blockage, we demonstrate that loss of neuronal CMA leads to altered neuronal function, selective changes in the neuronal metastable proteome, and proteotoxicity, all reminiscent of brain aging. Imposing CMA loss on a mouse model of Alzheimer's disease (AD) has synergistic negative effects on the proteome at risk of aggregation, thus increasing neuronal disease vulnerability and accelerating disease progression. Conversely, chemical enhancement of CMA ameliorates pathology in two different AD experimental mouse models. We conclude that functional CMA is essential for neuronal proteostasis through the maintenance of a subset of the proteome with a higher risk of misfolding than the general proteome.

Radiotherapy-exposed CD8+ and CD4+ neoantigens enhance tumor control

Neoantigens generated by somatic nonsynonymous mutations are key targets of tumor-specific T cells, but only a small number of mutations predicted to be immunogenic are presented by MHC molecules on cancer cells. Vaccination studies in mice and patients have shown that the majority of neoepitopes that elicit T cell responses fail to induce significant antitumor activity, for incompletely understood reasons. We report that radiotherapy upregulates the expression of genes containing immunogenic mutations in a poorly immunogenic mouse model of triple-negative breast cancer. Vaccination with neoepitopes encoded by these genes elicited CD8+ and CD4+ T cells that, whereas ineffective in preventing tumor growth, improved the therapeutic efficacy of radiotherapy. Mechanistically, neoantigen-specific CD8+ T cells preferentially killed irradiated tumor cells. Neoantigen-specific CD4+ T cells were required for the therapeutic efficacy of vaccination and acted by producing Th1 cytokines, killing irradiated tumor cells, and promoting epitope spread. Such a cytotoxic activity relied on the ability of radiation to upregulate class II MHC molecules as well as the death receptors FAS/CD95 and DR5 on the surface of tumor cells. These results provide proof-of-principle evidence that radiotherapy works in concert with neoantigen vaccination to improve tumor control.

Human Lymph: Formation Transport and Immunological role

The pre-nodal afferent lymph is the fluid which directly derives from the extracellular milieu from every parenchymal organ and, as it continues to circulate between the cells, it collects products deriving from the organ metabolism/catabolism. A comprehensive qualitative and quantitative investigation of the self-antigenic repertoire transported by the human lymph and its role in immunological recognition is still missing and is the focus of this investigation.

Using advanced proteomics and biochemical approaches; we sequenced the proteome/degradome/peptidome of the human lymph and compared it with the MHC II peptidome displayed by HLA-DR1+ dendritic cells.

Analysis of more than 3000 sequences identified self-peptides derived from both intracellular and extracellular proteins revealing the variety of catabolic products transported by human lymph. Quantitative analysis established that at least some of these peptides are present in the circulating lymph in nanomolar concentration. Processing enzymes were identified by reference to a database of experimentally determined cleavage sites. We found that self-antigens processed by tissue-specific proteases, including matrix metalloproteases, caspases, and granzymes, and carried by lymph contribute to the MHC II self-peptidome presented by conventional dendritic cells in vivo. Our work brings new attention to the role of “immunological self-recognition” as a dynamic interaction between dendritic cells and the lymph-transported metabolic/catabolic products from parenchymal organ derived from tissue growth, remodeling, and physiological apoptosis.

In vivo data: treatment with the F11R/JAM-A peptide 4D decreases mortality and reduces the generation of atherosclerotic plaques in ApoE-deficient mice

The data in this article focus on the F11 Receptor (F11R/JAM-A; Junctional Adhesion Molecule-A; JAM-A, F11R), a cell adhesion protein constitutively expressed on the membrane surface of circulating platelets and localized within the tight junctions of healthy endothelial cells (ECs). Previous reports have shown that F11R/JAM-A plays a critical role in the adhesion of platelets to an inflamed endothelium due to its' pathological expression on the luminal surface of the cytokine-inflamed endothelium. Since platelet adhesion to an inflamed endothelium is an early step in the development of atherosclerotic plaque formation, and with time, resulting in heart attacks and stroke, we conducted a long-term, study utilizing the atherosclerosis-prone ApoE ^-/- mice to attempt a blockade of the formation of atherosclerotic plaques by preventing the adhesion of platelets to the inflamed vasculature in vivo. Utilizing a nonhydrolyzable peptide derived from an amino acid sequence of F11R/JAM-A, peptide 4D, we have shown in culture that the adhesion of platelets to the inflamed endothelial cells could be blocked by peptide 4D. The present data demonstrate the positive health benefits of chronic peptide 4D administration to the atherosclerosis-prone ApoE^-/- mice, and provides new information for potential use of this F11R derived peptide in the prevention of atherosclerosis. The data presented in this article provide further experimental support for the study presented in Babinska et al., Atherosclerosis 284 (2019) 92-101.

Lymphatic remodelling in response to lymphatic injury in the hind limbs of sheep

Contractile activity in the lymphatic vasculature is essential for maintaining fluid balance within organs and tissues. However, the mechanisms by which collecting lymphatics adapt to changes in fluid load and how these adaptations influence lymphatic contractile activity are unknown. Here we report a model of lymphatic injury based on the ligation of one of two parallel lymphatic vessels in the hind limb of sheep and the evaluation of structural and functional changes in the intact, remodelling lymphatic vessel over a 42-day period. We show that the remodelled lymphatic vessel displayed increasing intrinsic contractile frequency, force generation and vessel compliance, as well as decreasing flow-mediated contractile inhibition via the enzyme endothelial nitric oxide synthase. A computational model of a chain of lymphatic contractile segments incorporating these adaptations predicted increases in the flow-generation capacity of the remodelled vessel at the expense of normal mitochondrial function and elevated oxidative stress within the lymphatic muscle. Our findings may inform interventions for mitigating lymphatic muscle fatigue in patients with dysfunctional lymphatics.

Lymphatic Cannulation for Lymph Sampling and Molecular Delivery

Unlike the blood, the interstitial fluid and the deriving lymph are directly bathing the cellular layer of each organ. As such, composition analysis of the lymphatic fluid can provide more precise biochemical and cellular information on an organ's health and be a valuable resource for biomarker discovery. In this study, we describe a protocol for cannulation of mouse and rat lymphatic collectors that is suitable for the following: the "omic" sampling of pre- and postnodal lymph, collected from different anatomical districts; the phenotyping of immune cells circulating between parenchymal organs and draining lymph nodes; injection of known amounts of molecules for quantitative immunological studies of nodal trafficking and/or clearance; and monitoring an organ's biochemical omic changes in pathological conditions. Our data indicate that probing the lymphatic fluid can provide an accurate snapshot of an organ's physiology/pathology, making it an ideal target for liquid biopsy.

Tumor-associated factors are enriched in lymphatic exudate compared to plasma in metastatic melanoma patients

Liquid biopsies allow monitoring of cancer progression and detection of relapse, but reliable biomarkers in melanoma are lacking. Because secreted factors preferentially drain to lymphatic vessels before dilution in the blood, we hypothesized that lymph should be vastly enriched in cancer biomarkers. We characterized postoperative lymphatic exudate and plasma of metastatic melanoma patients after lymphadenectomy and found a dramatic enrichment in lymphatic exudate of tumor-derived factors and especially extracellular vesicles containing melanoma-associated proteins and miRNAs, with unique protein signatures reflecting early versus advanced metastatic spread. Furthermore, lymphatic exudate was enriched in memory T cells, including tumor-reactive CD137+ and stem cell-like types. In mice, lymph vessels were the major route of extracellular vesicle transport from tumors to the systemic circulation. We suggest that lymphatic exudate provides a rich source of tumor-derived factors for enabling the discovery of novel biomarkers that may reflect disease stage and therapeutic response.

The negative effect of lipid challenge on autophagy inhibits T cell responses

Obesity is associated with changes in the immune system that significantly hinder its ability to mount efficient immune responses. Previous studies have reported a dysregulation of immune responses caused by lipid challenge; however, the mechanisms underlying that dysregulation are still not completely understood. Autophagy is an essential catabolic process through which cellular components are degraded by the lysosomal machinery. In T cells, autophagy is an actively regulated process necessary to sustain homeostasis and activation. Here, we report that CD4⁺ T cell responses are inhibited when cells are challenged with increasing concentrations of fatty acids. Furthermore, analysis of T cells from diet-induced obese mice confirms that high lipid load inhibits activation-induced responses in T cells. We have found that autophagy is inhibited in CD4⁺ T cells exposed in vitro or in vivo to lipid stress, which causes decreased autophagosome formation and degradation. Supporting that inhibition of autophagy caused by high lipid load is a key mechanism that accounts for the effects on T cell function of lipid stress, we found that ATG7 (autophagy-related 7)-deficient T cells, unable to activate autophagy, did not show additional inhibitory effects on their responses to activation when subjected to lipid challenge. Our results indicate, thus, that increased lipid load can dysregulate autophagy and cause defective T cell responses, and suggest that inhibition of autophagy may underlie some of the characteristic obesity-associated defects in the T cell compartment.Abbreviations: ACTB: actin, beta; ATG: autophagy-related; CDKN1B: cyclin-dependent kinase inhibitor 1B; HFD: high-fat diet; IFNG: interferon gamma; IL: interleukin; MAPK1/ERK2: mitogen-activated protein kinase 1; MAPK3/ERK1: mitogen-activated protein kinase 3; MAPK8/JNK: mitogen-activated protein kinase 8; LC3-I: non-conjugated form of MAP1LC3B; LC3-II: phosphatidylethanolamine-conjugated form of MAP1LC3B; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MS: mass spectrometry; MTOR: mechanistic target of rapamycin kinase; NFATC2: nuclear factor of activated T cells, cytoplasmic, calcineurin dependent 2; NLRP3: NLR family, pyrin domain containing 3; OA: oleic acid; PI: propidium iodide; ROS: reactive oxygen species; STAT5A: signal transducer and activator of transcription 5A; TCR: T cell receptor; T_H1: T helper cell type 1.

Senescence cell-associated extracellular vesicles serve as osteoarthritis disease and therapeutic markers

Senescent cells (SnCs) are increasingly recognized as central effector cells in age-related pathologies. Extracellular vesicles (EVs) are potential cellular communication tools through which SnCs exert central effector functions in the local tissue environment. To test this hypothesis in a medical indication that could be validated clinically, we evaluated EV production from SnCs enriched from chondrocytes isolated from human arthritic cartilage. EV production increased in a dose-responsive manner as the concentration of SnCs increased. The EVs were capable of transferring senescence to nonsenescent chondrocytes and inhibited cartilage formation by non-SnCs. microRNA (miR) profiles of EVs isolated from human arthritic synovial fluid did not fully overlap with the senescent chondrocyte EV profiles. The effect of SnC clearance was tested in a murine model of posttraumatic osteoarthritis. miR and protein profiles changed after senolytic treatment but varied depending on age. In young animals, senolytic treatment altered expression of miR-34a, -30c, -125a, -24, -92a, -150, and -186, and this expression correlated with cartilage production. The primary changes in EV contents in aged mice after senolytic treatment, which only reduced pain and degeneration, were immune related. In sum, EV contents found in synovial fluid may serve as a diagnostic for arthritic disease and indicator for therapeutic efficacy of senolytic treatment.

Involvement of Akt in mitomycin C and its analog triggered cytotoxicity in MCF-7 and K562 cancer cells

Mitomycin C (MC) is a well-known DNA alkylating agent. MC analog, 10-decarbamoyl mitomycin C (DMC), unlike MC, has stronger effects on cancer with p53 mutation. We previously demonstrated that MC/DMC could activate p21WAF1/CIP1 in MCF-7 (p53-proficient) and K562 (p53-deficient) cells in a p53-independent mode. This study aimed to elucidate the upstream signaling pathway of p21WAF1/CIP1 activation triggered by MC/DMC. Besides p53, Akt plays an important role on deactivating p21WAF1/CIP1 . The results showed that MC/DMC inhibited Akt in MCF-7 cells, but not in K562 cells. By knocking down p53, the Akt inhibition in MCF-7 cells was alleviated. This implied that the deactivated Akt caused by MC/DMC was p53-dependent. With Akt activator (SC79), p21WAF1/CIP1 activation triggered by MC/DMC in MCF-7 cells was not reduced. This indicated that Akt inhibition triggered by MC/DMC was not associated with MC/DMC-induced p21WAF1/CIP1 activation. Label-free quantitative proteomic profiling analysis revealed that DMC has a stronger effect on down-regulating the PI3K/Akt signaling pathway in MCF-7 cells as compared to MC. No significant effect of MC/DMC on PI3K/Akt in K562 cells was observed. In summary, MC/DMC regulate Akt activation in a p53-dependent manner. This Akt deactivation is not associated with p21WAF1/CIP1 activation in response to MC/DMC.

In vitro model reveals a role for mechanical stretch in the remodeling response of lymphatic muscle cells

OBJECTIVE

Using primary LMCs in vitro, we sought to characterize the impact of LMC remodeling on their functional and molecular response to mechanical loading and culture conditions.

METHODS

Primary "wounded leg" LMCs were derived from the hindlimb of three sheep who underwent lymphatic injury 6 weeks prior, while "control leg" LMCs were derived from the contralateral, unwounded, limb. Function of the LMCs was characterized in response to media of variable levels of serum (10% vs 0.2%) and glucose (4.5 vs 1 g/L). Functional and proteomic data were evaluated in LMCs exposed to cyclic stretch (0.1 Hz, 7.5% elongation) for 1 week.

RESULTS

LMCs were sensitive to changes in serum levels, significantly reducing overall activity and collagen synthesis under low serum conditions. LMCs from the remodeled vessel had higher baseline levels of metabolic activity but not collagen synthesis. Cyclic loading induced cellular alignment perpendicular to the axis of stretch and alterations in signaling pathways associated with metabolism. Remodeled LMCs had consistently higher levels of metabolic activity and were more resistant to strain-induced apoptosis.

CONCLUSIONS

LMCs exist on a functional spectrum, becoming more active in response to stretching and maintaining phenotypic remodeling in response to local lymphatic/tissue damage.

Quantitative Profiling of the Lymph Node Clearance Capacity

Transport of tissue-derived lymphatic fluid and clearance by draining lymph nodes are pivotal for maintenance of fluid homeostasis in the body and for immune-surveillance of the self- and non-self-proteomes. Yet a quantitative analysis of nodal filtration of the tissue-derived proteome present in lymphatic fluid has not been reported. Here we quantified the efficiency of nodal clearance of the composite proteomic load using label-free and isotope-labeling proteomic analysis of pre-nodal and post-nodal samples collected by direct cannulation. These results were extended by quantitation of the filtration efficiency of fluorophore-labeled proteins, bacteria, and beads infused at physiological flow rates into pre-nodal lymphatic collectors and collected by post-nodal cannulation. We developed a linear model of nodal filtration efficiency dependent on pre-nodal protein concentrations and molecular weight, and uncovered criteria for disposing the proteome incoming from defined anatomical districts under physiological conditions. These findings are pivotal to understanding the maximal antigenic load sustainable by a draining node, and promote understanding of pathogen spreading and nodal filtration of tumor metastasis, potentially helping to improve design of vaccination protocols, immunization strategies and drug delivery.

Sequence-Dependent Diastereospecific and Diastereodivergent Crosslinking of DNA by Decarbamoylmitomycin C

Mitomycin C (MC), a potent antitumor drug, and decarbamoylmitomycin C (DMC), a derivative lacking the carbamoyl group, form highly cytotoxic DNA interstrand crosslinks. The major interstrand crosslink formed by DMC is the C1'' epimer of the major crosslink formed by MC. The molecular basis for the stereochemical configuration exhibited by DMC was investigated using biomimetic synthesis. The formation of DNA-DNA crosslinks by DMC is diastereospecific and diastereodivergent: Only the 1''S-diastereomer of the initially formed monoadduct can form crosslinks at GpC sequences, and only the 1''R-diastereomer of the monoadduct can form crosslinks at CpG sequences. We also show that CpG and GpC sequences react with divergent diastereoselectivity in the first alkylation step: 1"S stereochemistry is favored at GpC sequences and 1''R stereochemistry is favored at CpG sequences. Therefore, the first alkylation step results, at each sequence, in the selective formation of the diastereomer able to generate an interstrand DNA-DNA crosslink after the "second arm" alkylation. Examination of the known DNA adduct pattern obtained after treatment of cancer cell cultures with DMC indicates that the GpC sequence is the major target for the formation of DNA-DNA crosslinks in vivo by this drug.

Bradykinin mediates the secretion of coagulation factor VIII by mouse dendritic cells

Recent experimental evidences proved that kinins, which are a family of octa- to decapeptides structurally related to bradykinin (BK), have modulatory effects on multiple players of the immune system, including macrophages, dendritic cells (DC), T and B lymphocytes, and induce the activation, proliferation, migration, and effector functions of these cells. To further understand the molecular mechanisms underlying bradykinin mediated activation of DCs, we have employed global proteomics and transcriptomic (mRNA) profiling of mouse DCs activated by BK peptide (RPPGFSPFR). The proteomics profiling was performed using a combination of label-free nanoLC-ESI MS/MS and 2D-DIGE analysis. C57BL/6J wild type mice were treated with: 1) BK, or 2) Captopril, an ACE inhibitor that enhances the endogenous BK, or 3) a combination of both drugs (BK+CAP). Following treatment, the DCs (CD11c+) were purified by immunomagnetic sorting. Comparative Ingenuity Pathway Analysis (IPA) identified the upregulated cellular pathways in the BK/CAP/BK+CAP treated DCs, highlighting molecules involved in the DCs migration/chemotaxis, MHC-I and MHC-II expression, antigen presentation pathways, inflammation and cytokines secretion. Moreover, both the comparative proteomics and the transcriptomic analyses demonstrated the significant upregulation of the coagulation pathway (e.g. coagulation factors V, VII, VIII and PAR2 and PAR3 receptors) in the purified DCs from treated mice. Production of coagulation factors V and VIII by BK-activated DCs was validated by RT-PCR, and by immunofluorescence. Our research highlights novel cellular pathways that regulate the cross-talk between inflammation and coagulation in the bradykinin activated DCs.

Structural and Biological Interaction of hsc-70 Protein with Phosphatidylserine in Endosomal Microautophagy

hsc-70 (HSPA8) is a cytosolic molecular chaperone, which plays a central role in cellular proteostasis, including quality control during protein refolding and regulation of protein degradation. hsc-70 is pivotal to the process of macroautophagy, chaperone-mediated autophagy, and endosomal microautophagy. The latter requires hsc-70 interaction with negatively charged phosphatidylserine (PS) at the endosomal limiting membrane. Herein, by combining plasmon resonance, NMR spectroscopy, and amino acid mutagenesis, we mapped the C terminus of the hsc-70 LID domain as the structural interface interacting with endosomal PS, and we estimated an hsc-70/PS equilibrium dissociation constant of 4.7 ± 0.1 μm. This interaction is specific and involves a total of 4-5 lysine residues. Plasmon resonance and NMR results were further experimentally validated by hsc-70 endosomal binding experiments and endosomal microautophagy assays. The discovery of this previously unknown contact surface for hsc-70 in this work elucidates the mechanism of hsc-70 PS/membrane interaction for cytosolic cargo internalization into endosomes.

Development of new antiatherosclerotic and antithrombotic drugs utilizing F11 receptor (F11R/JAM-A) peptides

Peptides with enhanced resistance to proteolysis, based on the amino acid sequence of the F11 receptor molecule (F11R, aka JAM-A/Junctional adhesion molecule-A), were designed, prepared, and examined as potential candidates for the development of anti-atherosclerotic and anti-thrombotic therapeutic drugs. A sequence at the N-terminal of F11R together with another sequence located in the first Ig-loop of this protein, were identified to form a steric active-site operating in the F11R-dependent adhesion between cells that express F11R molecules on their external surface. In silico modeling of the complex between two polypeptide chains with the sequences positioned in the active-site was used to generate peptide-candidates designed to inhibit homophilic interactions between surface-located F11R molecules. The two lead F11R peptides were modified with D-Arg and D-Lys at selective sites, for attaining higher stability to proteolysis in vivo. Using molecular docking experiments we tested different conformational states and the putative binding affinity between two selected D-Arg and D-Lys-modified F11R peptides and the proposed binding pocket. The inhibitory effects of the F11R peptide 2HN-(dK)-SVT-(dR)-EDTGTYTC-CONH2 on antibody-induced platelet aggregation and on the adhesion of platelets to cytokine-inflammed endothelial cells are reported in detail, and the results point out the significant potential utilization of F11R peptides for the prevention and treatment of atherosclerotic plaques and associated thrombotic events.

Autoimmune response to transthyretin in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatological condition. Although it has been proposed that JIA has an autoimmune component, the autoantigens are still unknown. Using biochemical and proteomic approaches, we identified the molecular chaperone transthyretin (TTR) as an antigenic target for B and T cell immune responses. TTR was eluted from IgG complexes and affinity purified from 3 JIA patients, and a statistically significant increase in TTR autoantibodies was observed in a group of 43 JIA patients. Three cryptic, HLA-DR1-restricted TTR peptides, which induced CD4⁺ T cell expansion and IFN-γ and TNF-α production in 3 out of 17 analyzed patients, were also identified. Misfolding, aggregation and oxidation of TTR, as observed in the synovial fluid of all JIA patients, enhanced its immunogenicity in HLA-DR1 transgenic mice. Our data point to TTR as an autoantigen potentially involved in the pathogenesis of JIA and to oxidation and aggregation as a mechanism facilitating TTR autoimmunity.

The Dendritic Cell Major Histocompatibility Complex II (MHC II) Peptidome Derives from a Variety of Processing Pathways and Includes Peptides with a Broad Spectrum of HLA-DM Sensitivity

The repertoire of peptides displayed in vivo by MHC II molecules derives from a wide spectrum of proteins produced by different cell types. Although intracellular endosomal processing in dendritic cells and B cells has been characterized for a few antigens, the overall range of processing pathways responsible for generating the MHC II peptidome are currently unclear. To determine the contribution of non-endosomal processing pathways, we eluted and sequenced over 3000 HLA-DR1-bound peptides presented in vivo by dendritic cells. The processing enzymes were identified by reference to a database of experimentally determined cleavage sites and experimentally validated for four epitopes derived from complement 3, collagen II, thymosin β4, and gelsolin. We determined that self-antigens processed by tissue-specific proteases, including complement, matrix metalloproteases, caspases, and granzymes, and carried by lymph, contribute significantly to the MHC II self-peptidome presented by conventional dendritic cells in vivo. Additionally, the presented peptides exhibited a wide spectrum of binding affinity and HLA-DM susceptibility. The results indicate that the HLA-DR1-restricted self-peptidome presented under physiological conditions derives from a variety of processing pathways. Non-endosomal processing enzymes add to the number of epitopes cleaved by cathepsins, altogether generating a wider peptide repertoire. Taken together with HLA-DM-dependent and-independent loading pathways, this ensures that a broad self-peptidome is presented by dendritic cells. This work brings attention to the role of "self-recognition" as a dynamic interaction between dendritic cells and the metabolic/catabolic activities ongoing in every parenchymal organ as part of tissue growth, remodeling, and physiological apoptosis.

Aging-related anatomical and biochemical changes in lymphatic collectors impair lymph transport, fluid homeostasis, and pathogen clearance

The role of lymphatic vessels is to transport fluid, soluble molecules, and immune cells to the draining lymph nodes. Here, we analyze how the aging process affects the functionality of the lymphatic collectors and the dynamics of lymph flow. Ultrastructural, biochemical, and proteomic analysis indicates a loss of matrix proteins, and smooth muscle cells in aged collectors resulting in a decrease in contraction frequency, systolic lymph flow velocity, and pumping activity, as measured in vivo in lymphatic collectors. Functionally, this impairment also translated into a reduced ability for in vivo bacterial transport as determined by time-lapse microscopy. Ultrastructural and proteomic analysis also indicates a decrease in the thickness of the endothelial cell glycocalyx and loss of gap junction proteins in aged lymph collectors. Redox proteomic analysis mapped an aging-related increase in the glycation and carboxylation of lymphatic’s endothelial cell and matrix proteins. Functionally, these modifications translate into apparent hyperpermeability of the lymphatics with pathogen escaping from the collectors into the surrounding tissue and a decreased ability to control tissue fluid homeostasis. Altogether, our data provide a mechanistic analysis of how the anatomical and biochemical changes, occurring in aged lymphatic vessels, compromise lymph flow, tissue fluid homeostasis, and pathogen transport.

Age-related carbonylation of fibrocartilage structural proteins drives tissue degenerative modification

Aging-related oxidative stress has been linked to degenerative modifications in different organs and tissues. Using redox proteomic analysis and illustrative tandem mass spectrometry mapping, we demonstrate oxidative posttranslational modifications in structural proteins of intervertebral discs (IVDs) isolated from aging mice. Increased protein carbonylation was associated with protein fragmentation and aggregation. Complementing these findings, a significant loss of elasticity and increased stiffness was measured in fibrocartilage from aging mice. Studies using circular dichroism and intrinsic tryptophan fluorescence revealed a significant loss of secondary and tertiary structures of purified collagens following oxidation. Collagen unfolding and oxidation promoted both nonenzymatic and enzymatic degradation. Importantly, induction of oxidative modification in healthy fibrocartilage recapitulated the biochemical and biophysical modifications observed in the aging IVD. Together, these results suggest that protein carbonylation, glycation, and lipoxidation could be early events in promoting IVD degenerative changes.

Heat shock protein 70 inhibitors. 1. 2,5'-thiodipyrimidine and 5-(phenylthio)pyrimidine acrylamides as irreversible binders to an allosteric site on heat shock protein 70

Heat shock protein 70 (Hsp70) is an important emerging cancer target whose inhibition may affect multiple cancer-associated signaling pathways and, moreover, result in significant cancer cell apoptosis. Despite considerable interest from both academia and pharmaceutical companies in the discovery and development of druglike Hsp70 inhibitors, little success has been reported so far. Here we describe structure–activity relationship studies in the first rationally designed Hsp70 inhibitor class that binds to a novel allosteric pocket located in the N-terminal domain of the protein. These 2,5′-thiodipyrimidine and 5-(phenylthio)pyrimidine acrylamides take advantage of an active cysteine embedded in the allosteric pocket to act as covalent protein modifiers upon binding. The study identifies derivatives 17a and 20a, which selectively bind to Hsp70 in cancer cells. Addition of high nanomolar to low micromolar concentrations of these inhibitors to cancer cells leads to a reduction in the steady-state levels of Hsp70-sheltered oncoproteins, an effect associated with inhibition of cancer cell growth and apoptosis. In summary, the described scaffolds represent a viable starting point for the development of druglike Hsp70 inhibitors as novel anticancer therapeutics.

Heat shock protein 70 inhibitors. 2. 2,5'-thiodipyrimidines, 5-(phenylthio)pyrimidines, 2-(pyridin-3-ylthio)pyrimidines, and 3-(phenylthio)pyridines as reversible binders to an allosteric site on heat shock protein 70

The discovery and development of heat shock protein 70 (Hsp70) inhibitors is currently a hot topic in cancer. In the preceding paper in this issue (10.1021/jm401551n), we have described structure–activity relationship studies in the first Hsp70 inhibitor class rationally designed to bind to a novel allosteric pocket located in the N-terminal domain of the protein. These ligands contained an acrylamide to take advantage of an active cysteine embedded in the allosteric pocket and acted as covalent protein modifiers upon binding. Here, we perform chemical modifications around the irreversible inhibitor scaffold to demonstrate that covalent modification is not a requirement for activity within this class of compounds. The study identifies derivative 27c, which mimics the biological effects of the irreversible inhibitors at comparable concentrations. Collectively, the back-to-back manuscripts describe the first pharmacophores that favorably and selectively interact with a never explored pocket in Hsp70 and provide a novel blueprint for a cancer-oriented development of Hsp70-directed ligands.

The lymph self-antigen repertoire

The lymphatic fluid originates from the interstitial fluid which bathes every parenchymal organ and reflects the “omic” composition of the tissue from which it originates in its physiological or pathological signature. Several recent proteomic analyses have mapped the proteome-degradome and peptidome of this immunologically relevant fluid pointing to the lymph as an important source of tissue-derived self-antigens. A vast array of lymph-circulating peptides have been mapped deriving from a variety of processing pathways including caspases, cathepsins, MMPs, ADAMs, kallikreins, calpains, and granzymes, among others. These self peptides can be directly loaded on circulatory dendritic cells and expand the self-antigenic repertoire available for central and peripheral tolerance.

Protein expression profiles of human lymph and plasma mapped by 2D-DIGE and 1D SDS-PAGE coupled with nanoLC-ESI-MS/MS bottom-up proteomics

In this study a proteomic approach was used to define the protein content of matched samples of afferent prenodal lymph and plasma derived from healthy volunteers. The analysis was performed using two analytical methodologies coupled with nanoliquid chromatography-tandem mass spectrometry: one-dimensional gel electrophoresis (1DEF nanoLC Orbitrap-ESI-MS/MS), and two-dimensional fluorescence difference-in-gel electrophoresis (2D-DIGE nanoLC-ESI-MS/MS). The 253 significantly identified proteins (p<0.05), obtained from the tandem mass spectrometry data, were further analyzed with pathway analysis (IPA) to define the functional signature of prenodal lymph and matched plasma. The 1DEF coupled with nanoLC-MS-MS revealed that the common proteome between the two biological fluids (144 out of 253 proteins) was dominated by complement activation and blood coagulation components, transporters and protease inhibitors. The enriched proteome of human lymph (72 proteins) consisted of products derived from the extracellular matrix, apoptosis and cellular catabolism. In contrast, the enriched proteome of human plasma (37 proteins) consisted of soluble molecules of the coagulation system and cell-cell signaling factors. The functional networks associated with both common and source-distinctive proteomes highlight the principal biological activity of these immunologically relevant body fluids.

Age-related oxidative stress compromises endosomal proteostasis

A hallmark of aging is an imbalance between production and clearance of reactive oxygen species and increased levels of oxidatively damaged biomolecules. Herein, we demonstrate that splenic and nodal antigen-presenting cells purified from aging mice accumulate oxidatively modified proteins with side-chain carbonylation, advanced glycation end products, and lipid peroxidation. Furthermore, we show that the endosomal accumulation of oxidatively modified proteins interferes with the efficient processing of exogenous antigens and degradation of macroautophagy-delivered proteins. In support of a causative role for oxidized products in the inefficient immune response, a decrease in oxidative stress improved the adaptive immune response to immunizing antigens. These findings underscore a previously unrecognized negative effect of age-dependent changes in cellular proteostasis on the immune response.

Annexin A2 binds to endosomes following organelle destabilization by particulate wear debris

Endosomal functions are contingent on the integrity of the organelle-limiting membrane, whose disruption induces inflammation and cell death. Here we show that phagocytosis of ultrahigh molecular weight polyethylene particles induces damage to the endosomal-limiting membrane and results in the leakage of cathepsins into the cytosol and NLRP3-inflammasome activation. Annexin A2 recruitment to damaged organelles is shown by two-dimensional DIGE protein profiling, endosomal fractionation, confocal analysis of endogenous and annexin A2-GFP transfected cells, and immunogold labelling. Binding experiments, using fluorescent liposomes, confirms annexin A2 recruitment to endosomes containing phagocytosed polyethylene particles. Finally, an increase in cytosolic cathepsins, NLRP3-inflammasome activation, and IL-1 production is seen in dendritic cells from annexin A2-null mice, following exposure to polyethylene particles. Together, the results indicate a functional role of annexin A2 binding to endosomal membranes following organelle destabilization.

Rational design and characterization of D-Phe-Pro-D-Arg-derived direct thrombin inhibitors

The tremendous social and economic impact of thrombotic disorders, together with the considerable risks associated to the currently available therapies, prompt for the development of more efficient and safer anticoagulants. Novel peptide-based thrombin inhibitors were identified using in silico structure-based design and further validated in vitro. The best candidate compounds contained both l- and d-amino acids, with the general sequence d-Phe(P3)-Pro(P2)-d-Arg(P1)-P1′-CONH₂. The P1′ position was scanned with l- and d-isomers of natural or unnatural amino acids, covering the major chemical classes. The most potent non-covalent and proteolysis-resistant inhibitors contain small hydrophobic or polar amino acids (Gly, Ala, Ser, Cys, Thr) at the P1′ position. The lead tetrapeptide, d-Phe-Pro-d-Arg-d-Thr-CONH₂, competitively inhibits α-thrombin's cleavage of the S2238 chromogenic substrate with a K_i of 0.92 µM. In order to understand the molecular details of their inhibitory action, the three-dimensional structure of three peptides (with P1′ l-isoleucine (fPrI), l-cysteine (fPrC) or d-threonine (fPrt)) in complex with human α-thrombin were determined by X-ray crystallography. All the inhibitors bind in a substrate-like orientation to the active site of the enzyme. The contacts established between the d-Arg residue in position P1 and thrombin are similar to those observed for the l-isomer in other substrates and inhibitors. However, fPrC and fPrt disrupt the active site His57-Ser195 hydrogen bond, while the combination of a P1 d-Arg and a bulkier P1′ residue in fPrI induce an unfavorable geometry for the nucleophilic attack of the scissile bond by the catalytic serine. The experimental models explain the observed relative potency of the inhibitors, as well as their stability to proteolysis. Moreover, the newly identified direct thrombin inhibitors provide a novel pharmacophore platform for developing antithrombotic agents by exploring the conformational constrains imposed by the d-stereochemistry of the residues at positions P1 and P1′.

Oxidative stress, inflamm-aging and immunosenescence

Immunosenescence is characterized by a decreased ability of the immune system to respond to foreign antigens, as well as a decreased ability to maintain tolerance to self-antigens. This results in an increased susceptibility to infection and cancer and reduced responses to vaccination [1-5]. The mechanisms underlying immunosenescence comprise a series of cellular and molecular events involving alteration of several biochemical pathways and different cellular populations, and for the most part our understanding of these molecular mechanisms is still fragmentary. In this review we will focus on the process of senescence associated with oxidative stress, in particular how protein oxidation alters the functionality of immune cells and how oxidative stress contributes to a chronic inflammatory process often referred as inflamm-aging.

Crystallization and preliminary crystallographic characterization of three peptidic inhibitors in complex with α-thrombin

The serine protease thrombin plays a major role in thrombosis and haemostasis. This has driven interest in thrombin inhibitors as potential antithrombotic drugs. Here, the crystallization and preliminary crystallographic analysis of human α-thrombin in complex with three noncovalent peptide inhibitors of the general sequence D-Phe-Pro-D-Arg-P1'-CONH2 are reported. The crystals belonged to the orthorhombic space group P2(1)2(1)2(1) and diffracted to beyond 1.3 Å resolution.

Design of a flexible cell-based assay for the evaluation of heat shock protein 70 expression modulators

Heat shock protein 70 (Hsp70) is a chaperone protein that helps protect against cellular stress, a function that may be co-opted to fight human diseases. In particular, the upregulation of Hsp70 can suppress the neurotoxicity of misfolded proteins, suggesting possible therapeutic strategies in neurodegenerative diseases. Alternatively, in cancer cells where high levels of Hsp70 inhibit both intrinsic and extrinsic apoptotic pathways, a reduction in Hsp70 levels may induce apoptosis. To evaluate and identify, in a single assay format, small molecules that induce or inhibit endogenous Hsp70, we have designed and optimized a microtiter assay that relies on whole-cell immunodetection of Hsp70. The assay utilizes a minimal number of neuronal or cancer cells, yet is sufficiently sensitive and reproducible to permit quantitative determinations. We further validated the assay using a panel of Hsp70 modulators. In conclusion, we have developed an assay that is fast, robust, and cost efficient. As such, it can be implemented in most research laboratories. The assay should greatly improve the speed at which novel Hsp70 inducers and inhibitors of expression can be identified and evaluated.

The lymph as a pool of self-antigens

Prenodal lymph is generated from the interstitial fluid that surrounds organs, and thus contains products of organ metabolism and catabolism. New proteomic analyses of lymph have identified proteins and peptides that are derived from capillary extravasation and tissue-specific proteins. Many of these peptides are detected at nanomolar concentrations in the lymph before passage through a regional lymph node. Before entering the node and once inside, proteins and processed peptides are filtered from the lymph by circulating immature dendritic cells (DCs) or non-activated nodal antigen-presenting cells (APCs) (macrophages, B cells and immature DCs). Here, we suggest that this process ensures organ-specific self-antigens are displayed to circulating and nodal APCs, thus contributing to the maintenance of peripheral tolerance.

Endosomal damage and TLR2 mediated inflammasome activation by alkane particles in the generation of aseptic osteolysis

Ultra-high molecular weight polyethylene is widely used as a bearing surface in prosthetic arthroplasty. Over time the generation of implant-derived wear particles can initiate an inflammatory reaction characterized by periprosthetic inflammation and ultimately bone resorption at the prosthetic bone interface. Herein we present evidence that the different sized particles as well as the different length alkane polymers generated by implant wear leads to a two component inflammatory response. Polymeric alkane structures, with side chain oxidations, directly bind and activate the TLR-1/2 signaling pathway. Whereas micron- and nanometer-sized particulate debris are extensively phagocyted and induce enlargement, fusion and disruption of endosomal compartments. The resulting lysosomal damage and subsequent enzymatic leakage induces the NALP3 inflammasome activation as determined by cathepsins S and B cytosolic release, Caspase 1 activation and processing of pro-IL-1beta, and pro-IL-18. These two processes synergistically results in the initiation of a strong inflammatory response with consequent cellular necrosis and extracellular matrix degradation.

Synthesis of an oligodeoxyribonucleotide adduct of mitomycin C by the postoligomerization method via a triamino mitosene

The cancer chemotherapeutic agent mitomycin C (MC) alkylates and cross-links DNA monofunctionally and bifunctionally in vivo and in vitro, forming six major MC-deoxyguanosine adducts of known structures. The synthesis of one of the monoadducts (8) by the postoligomerization method was accomplished both on the nucleoside and oligonucleotide levels, the latter resulting in the site-specific placement of 8 in a 12-mer oligodeoxyribonucleotide 26. This is the first application of this method to the synthesis of a DNA adduct of a complex natural product. Preparation of the requisite selectively protected triaminomitosenes 14 and 24 commenced with removal of the 10-carbamoyl group from MC, followed by reductive conversion to 10-decarbamoyl-2,7-diaminomitosene 10. This substance was transformed to 14 or 24 in several steps. Both were successfully coupled to the 2-fluoro-O(6)-(2-trimethylsilylethyl)deoxyinosine residue of the 12-mer oligonucleotide. The N(2)-phenylacetyl protecting group of 14 after its coupling to the 12-mer oligonucleotide could not be removed by penicillinamidase as expected. Nevertheless, the Teoc protecting group of 24 after coupling to the 12-mer oligonucleotide was removed by treatment with ZnBr2 to give the adducted oligonucleotide 26. However, phenylacetyl group removal was successful on the nucleoside-level synthesis of adduct 8. Proof of the structure of the synthetic nucleoside adduct included HPLC coelution and identical spectral properties with a natural sample, and (1)H NMR. Structure proof of the adducted oligonucleotide 26 was provided by enzymatic digestion to nucleosides and authentic adduct 8, as well as MS and MS/MS analysis.

Immunogenecity of modified alkane polymers is mediated through TLR1/2 activation

BACKGROUND

With the advancement of biomedical technology, artificial materials have been developed to replace diseased, damaged or nonfunctional body parts. Among such materials, ultra high molecular weight alkane or modified alkyl polymers have been extensively used in heart valves, stents, pacemakers, ear implants, as well as total joint replacement devices. Although much research has been undertaken to design the most non-reactive biologically inert polyethylene derivatives, strong inflammatory responses followed by rejection and failure of the implant have been noted.

METHODOLOGY/PRINCIPAL FINDINGS

Purification of the alkane polymers from the site of inflammation revealed extensive "in vivo" oxidation as detected by fourier transformed infra-red spectroscopy. Herein, we report the novel observation that oxidized alkane polymers induced activation of TLR1/2 pathway as determined by ligand dependent changes in intrinsic tyrosine fluorescence intensity and NF-kappaB luciferase gene assays. Oxidized polymers were very effective in activating dendritic cells and inducing secretion of pro-inflammatory cytokines. Molecular docking of the oxidized alkanes designated ligand specificity and polymeric conformations fitting into the TLR1/2 binding grooves.

CONCLUSION/SIGNIFICANCE

This is the first report of a synthetic polymer activating immune responses through TLR binding.

Design of a fluorescence polarization assay platform for the study of human Hsp70

The 70kDa heat shock proteins (Hsp70) are molecular chaperones that assist in folding of newly synthesized polypeptides, refolding or denaturation of misfolded proteins, and translocation of proteins across biological membranes. In addition, Hsp70 play regulatory roles in signal transduction, cell cycle, and apoptosis. Here, we present a novel assay platform based on fluorescence polarization that is suitable for investigating the yet elusive molecular mechanics of human Hsp70 allosteric regulation.