The emerging role of progesterone receptor membrane component 1 (PGRMC1) in cancer biology.

Progesterone receptor membrane component 1 (PGRMC1) is a multi-functional protein with a heme-binding moiety related to that of cytochrome b5, which is a putative progesterone receptor. The recently solved PGRMC1 structure revealed that heme-binding involves coordination by a tyrosinate ion at Y113, and induces dimerization which is stabilized by hydrophobic stacking of heme on adjacent monomers. Dimerization is required for association with cytochrome P450 (cyP450) enzymes, which mediates chemoresistance to doxorubicin and may be responsible for PGRMC1's anti-apoptotic activity. Here we review the multiple attested involvement of PGRMC1 in diverse functions, including regulation of cytochrome P450, steroidogenesis, vesicle trafficking, progesterone signaling and mitotic spindle and cell cycle regulation. Its wide range of biological functions is attested to particularly by its emerging association with cancer and progesterone-responsive female reproductive tissues. PGRMC1 exhibits all the hallmarks of a higher order nexus signal integration hub protein. It appears capable of acting as a detector that integrates information from kinase/phosphatase pathways with heme and CO levels and probably redox status.

Plant Phenols as Antibiotic Boosters: In Vitro Interaction of Olive Leaf Phenols with Ampicillin.

The antimicrobial properties of olive leaf extract (OLE) have been well recognized in the Mediterranean traditional medicine. Few studies have investigated the antimicrobial properties of OLE. In this preliminary study, commercial OLE and its major phenolic secondary metabolites were evaluated in vitro for their antimicrobial activities against Escherichia coli and Staphylococcus aureus, both individually and in combination with ampicillin. Besides luteolin 7-O-glucoside, OLE and its major phenolic secondary metabolites were effective against both bacteria, with more activity on S. aureus. In combination with ampicillin, OLE, caffeic acid, verbascoside and oleuropein showed additive effects. Synergistic interaction was observed between ampicillin and hydroxytyrosol. The phenolic composition of OLE and the stability of olive phenols in assay medium were also investigated. While OLE and its phenolic secondary metabolites may not be potent enough as stand-alone antimicrobials, their abilities to boost the activity of co-administered antibiotics constitute an imperative future research area.

An anti-inflammatory role for leukemia inhibitory factor receptor signaling in regenerating skeletal muscle.

Skeletal muscle regeneration in pathology and following injury requires the coordinated actions of inflammatory cells and myogenic cells to remove damaged tissue and rebuild syncytial muscle cells, respectively. Following contusion injury to muscle, the cytokine leukemia inhibitor factor (LIF) is up-regulated and knockout of Lif negatively impacts on morphometric parameters of muscle regeneration. Although it was speculated that LIF regulates muscle regeneration through direct effects on myogenic cells, the inflammatory effects of LIF have not been examined in regenerating skeletal muscle. Therefore, the expression and function of LIF was examined using the antagonist MH35-BD during specific inflammatory and myogenic stages of notexin-induced muscle regeneration in mice. LIF protein and mRNA were up-regulated in two distinct phases following intramuscular injection of notexin into tibialis anterior muscles. The first phase of LIF up-regulation coincided with the increased expression of pro-inflammatory cytokines; the second phase coincided with myogenic differentiation and formation of new myotubes. Administration of the LIF receptor antagonist MH35-BD during the second phase of LIF up-regulation had no significant effects on transcript expression of genes required for myogenic differentiation or associated with inflammation; there were no significant differences in morphometric parameters of the regenerating muscle. Conversely, when MH35-BD was administered during the acute inflammatory phase, increased gene transcripts for the pro-inflammatory cytokines Tnf (Tumor necrosis factor), Il1b (Interleukin-1ß) and Il6 (Interleukin-6) alongside an increase in the number of Ly6G positive neutrophils infiltrating the muscle were observed. This was followed by a reduction in Myog (Myogenin) mRNA, which is required for myogenic differentiation, and the subsequent number of myotubes formed was significantly decreased in MH35-BD-treated groups compared to sham. Thus, antagonism of the LIF receptor during the inflammatory phase of skeletal muscle regeneration appeared to induce an inflammatory response that inhibited subsequent myotube formation. We propose that the predominant role of LIF in skeletal muscle regeneration appears to be in regulating the inflammatory response rather than directly effecting myogenic cells.

Patient experiences of codesigned rehabilitation interventions in hospitals: a rapid review.

BACKGROUND: Codesign strengthens partnerships between healthcare workers and patients. It also facilitates collaborations supporting the development, design and delivery of healthcare services. Prior rehabilitation reviews have focused mainly on the clinical and organisational outcomes of codesign with less focus on the lived experience of rehabilitation patients. OBJECTIVE: To explore patient experiences of codesigned hospital rehabilitation interventions. DESIGN: Rapid review and evidence synthesis of the literature. DATA SOURCES: CINAHL, MEDLINE, Embase and Cochrane were searched from 1 January 2000 to 25 April 2022. STUDY SELECTION: Studies reporting patient experiences of codesigned rehabilitation interventions in hospitals. RESULTS: 4156 studies were screened, and 38 full-text studies were assessed for eligibility. Seven studies were included in the final rapid review. Five out of the seven studies involved neurological rehabilitation. All eligible studies used qualitative research methods. The main barriers to codesign were related to staffing and dedicated time allocated to face-to-face patient-therapist interactions. High-quality relationships between patients and their therapists were a facilitator of codesign. Thematic synthesis revealed that codesigned rehabilitation interventions can enable a meaningful experience for patients and facilitate tailoring of treatments to align with individual needs. Personalised rehabilitation increases patient involvement in rehabilitation planning, delivery and decision-making. It also promotes positive feelings of empowerment and hope. CONCLUSION: This rapid review supports the implementation of codesigned rehabilitation interventions to improve patient experiences in hospitals. PROSPERO REGISTRATION NUMBER: CRD42021264547.

In-silico Molecular Interaction of Short Synthetic Lipopeptide/Importin-alpha and In-vitro Evaluation of Transgene Expression Mediated by Liposome- Based Gene Carrier.

BACKGROUND: Lipopeptide-based gene carriers have shown low cytotoxicity, are capable of cell membrane penetration, are easy to manufacture and therefore are great potential candidates for gene delivery applications. OBJECTIVES: This study aims to explore a range of short synthetic lipopeptides, (Lau: Lauryl; Pal: Palmitoyl) consisting of an alkyl chain, one cysteine (C), 1 to 2 histidine (H), and lysine (K) residues by performing in-silico molecular interaction and in-vitro evaluation. METHODS: The molecular interactions between the lipopeptides and Importin-α receptor were performed using AutoDock Vina and Amber14. The lipopeptide/DNA complexes were evaluated in- -vitro for their interactions, particle size, zeta potential and transgene expression. Transfection efficiency of the lipopeptides and Pal-CKKHH-derived liposome was carried out based on luciferase transgene expression. RESULTS: The in-silico interaction showed that Lau-CKKH and Pal-CKKHH hypothetically expedited nuclear uptake. Both lipopeptides had lower binding energy (-6.3 kcal/mol and -6.2 kcal/mol, respectively), compared to the native ligand, viz, nuclear localization sequence (-5.4 kcal/mol). The short lipopeptides were able to condense DNA molecules and efficiently form compacted nanoparticles. Based on the in-vitro evaluation on COS-7, Pal-CKKHH was found to be the best transfection agent amongst the lipopeptides. Its transfection efficiency (ng Luc/mg total protein) increased up to ~3-fold higher (1163 + 55) as it was formulated with helper lipid DOPE (1:2). The lipopeptide- based liposome (Pal-CKKHH: DOPE=1:2) also facilitated luciferase transgene expression on human embryonic kidney cells (293T) and human cervical adenocarcinoma cells (HeLa) with transfection efficiency 1779 +52 and 260 + 22, respectively. CONCLUSION: Our study for the first time has shown that the fully synthesized short lipopeptide Pal- CKKHH is able to interact firmly with the Importin-α. The lipopeptide is able to condense DNA molecules efficiently, facilitate transgene expression, expedite the nuclear uptake process, and hence has the characteristics of a potential transfection agent.

PGRMC1 effects on metabolism, genomic mutation and CpG methylation imply crucial roles in animal biology and disease.

BACKGROUND: Progesterone receptor membrane component 1 (PGRMC1) is often elevated in cancers, and exists in alternative states of phosphorylation. A motif centered on PGRMC1 Y180 was evolutionarily acquired concurrently with the embryological gastrulation organizer that orchestrates vertebrate tissue differentiation. RESULTS: Here, we show that mutagenic manipulation of PGRMC1 phosphorylation alters cell metabolism, genomic stability, and CpG methylation. Each of several mutants elicited distinct patterns of genomic CpG methylation. Mutation of S57A/Y180/S181A led to increased net hypermethylation, reminiscent of embryonic stem cells. Pathways enrichment analysis suggested modulation of processes related to animal cell differentiation status and tissue identity, as well as cell cycle control and ATM/ATR DNA damage repair regulation. We detected different genomic mutation rates in culture. CONCLUSIONS: A companion manuscript shows that these cell states dramatically affect protein abundances, cell and mitochondrial morphology, and glycolytic metabolism. We propose that PGRMC1 phosphorylation status modulates cellular plasticity mechanisms relevant to early embryological tissue differentiation.

PGRMC1 phosphorylation affects cell shape, motility, glycolysis, mitochondrial form and function, and tumor growth.

BACKGROUND: Progesterone Receptor Membrane Component 1 (PGRMC1) is expressed in many cancer cells, where it is associated with detrimental patient outcomes. It contains phosphorylated tyrosines which evolutionarily preceded deuterostome gastrulation and tissue differentiation mechanisms. RESULTS: We demonstrate that manipulating PGRMC1 phosphorylation status in MIA PaCa-2 (MP) cells imposes broad pleiotropic effects. Relative to parental cells over-expressing hemagglutinin-tagged wild-type (WT) PGRMC1-HA, cells expressing a PGRMC1-HA-S57A/S181A double mutant (DM) exhibited reduced levels of proteins involved in energy metabolism and mitochondrial function, and altered glucose metabolism suggesting modulation of the Warburg effect. This was associated with increased PI3K/AKT activity, altered cell shape, actin cytoskeleton, motility, and mitochondrial properties. An S57A/Y180F/S181A triple mutant (TM) indicated the involvement of Y180 in PI3K/AKT activation. Mutation of Y180F strongly attenuated subcutaneous xenograft tumor growth in NOD-SCID gamma mice. Elsewhere we demonstrate altered metabolism, mutation incidence, and epigenetic status in these cells. CONCLUSIONS: Altogether, these results indicate that mutational manipulation of PGRMC1 phosphorylation status exerts broad pleiotropic effects relevant to cancer and other cell biology.

Role of a LIF antagonist in LIF and OSM induced MMP-1, MMP-3, and TIMP-1 expression by primary articular chondrocytes.

Cartilage degradation is mediated by matrix metalloproteinases (MMPs) and their inhibitors, tissue metalloproteinases (TIMPs), which are transcriptionally regulated by a variety of growth factors and cytokines. The levels of various MMPs as well as TIMPs have been shown to increase in response to certain cytokines. These include leukaemia inhibitory factor (LIF) and Oncostatin M (OSM), both of which have been detected in the synovial fluids of patients with rheumatoid arthritis (RA). However, the role of LIF and OSM in the regulation of various MMPs and TIMPs is still incompletely understood. The aims of this study were to examine the effects of LIF and OSM on MMP-1, MMP-3, and TIMP-1 production. In addition, the capacity of the LIF antagonist, MH35-BD, to block LIF and OSM induced MMP expression was examined. Primary chondrocytes, isolated from porcine metacarpophalangeal cartilage, were cultured in the presence and absence of LIF and OSM, with and without a predetermined concentration of the LIF antagonist. We analysed the levels of MMP-1, MMP-3 and TIMP-1 expression using qRT-PCR, Northern blot, and ELISA assays. The results indicate that LIF and OSM increase the expression of MMP-1, MMP-3, and TIMP-1 several fold. Furthermore their expression is reduced to basal levels in the presence of the LIF antagonist MH35-BD.

Preparation and in vitro evaluation of novel lipopeptide transfection agents for efficient gene delivery.

Gene therapy by delivery of nonviral expression vectors is highly desirable, due to their safety, stability, and suitability for production as bulk pharmaceuticals. However, low transfection efficiency remains a limiting factor in application on nonviral gene delivery. Despite recent advances in the field, there are still major obstacles to overcome. In an attempt to construct more efficient nonviral gene delivery vectors, we have designed a series of novel lipopeptide transfection agents, consisting of an alkyl chain, one cysteine, 1 to 4 histidine and 1 to 3 lysine residues. The lipopeptides were designed to facilitate dimerization (by way of the cysteine residues), DNA binding at neutral pH (making use of charged lysine residues), and endosomal escape (by way of weakly basic histidine residues). DNA/lipopeptide complexes were evaluated for their biophysical properties and transfection efficiencies. The number and identity of amino acids incorporated in the lipopeptide construct affected their DNA/lipopeptide complex forming capacity. As the number of lysine residues in the lipopeptide increased, the DNA complexes formed became more stable, had higher zeta potential (particle surface charge), and produced smaller mean particle sizes (typically 110 nm at a charge ratio of 5.0 and 240 nm at a charge ratio of 1.0). The effect of inclusion of histidines in the lipopeptide moiety had the opposite effect on complex formation to lysine, but was necessary for high transfection efficiency. In vitro transfection studies in COS-7 cells revealed that the efficiency of gene delivery of the luciferase encoding plasmid, pCMV-Luc, mediated by all the lipopeptides, was much higher than poly(L-lysine) (PLL), which has no endosomal escape system, and in two cases was slightly higher than that of branched polyethylenimine (PEI). Lipopeptides with at least two lysine residues and at least one histidine residue produced spontaneous transfection complexes with plasmid DNA, indicating that endosomal escape was achieved by incorporation of histidine residues. These low molecular weight peptides can be readily synthesized and purified and offer new insights into the mechanism of action of transfection complexes.

Fc-based cytokines : prospects for engineering superior therapeutics.

The application of Fc (fragment crystallizable)-based cytokines (the fusion of the constant region of IgG to a cytokine of interest) as biotherapeutic agents to modulate inflammatory and immune responses has become increasingly popular in recent years. This is because in their monomeric form, cytokines are relatively small molecules with short serum half-lives, which necessitates frequent administration and thus limits their clinical utility. To rectify the problem, attempts have been made to improve the stability of these agents in vivo. This has been achieved through diverse strategies such as modification with polyethylene glycol (PEGylation) or by ligating the cytokine to protein moieties such as the constant heavy chain of IgG, known as the Fc fragment. The construction of Fc chimeric proteins has been shown to improve pharmacokinetics. However, since there is an inverse relationship between the size of molecules and the rate at which they diffuse through mucus, Fc fusion constructs potentially have a lower rate of diffusion. Consequently, a compromise is reached whereby Fc constructs are engineered to incorporate ligated cytokines in a monomeric form (one molecule of cytokine fused to a single Fc dimer) rather than in a dimeric form (two molecules of cytokine fused to a single Fc dimer). A recent and novel approach to improve stability in serum is a procedure that involves sheathing cytokines in protective protein covers called latency peptides. The enclosed cytokine is protected from degradation and allowed to act where needed when the outer peptide cover is removed. For some applications, a reduced serum half-life is desirable; for example, where there is a need to reduce IgG levels in antibody-mediated diseases. To achieve this goal, a strategy called AbDeg, which involves enhanced Ig degradation, has been devised. This article provides an overview of the design and construction of Fc-based cytokines, in both dimeric and monomeric forms. Several examples of recent applications of such constructs, which include cytokine antagonism, cytokine traps, gene therapy and drug delivery, are also discussed. Other antibody-engineered constructs such as Fab (fragment, antigen binding) and single chain Fv (fragment, variable) fusions are also briefly covered.

In vitro evaluation of leukemia inhibitory factor receptor antagonists as candidate therapeutics for inflammatory arthritis.

Leukemia inhibitory factor (LIF) and oncostatin M (OSM) are found in appreciable concentrations in synovial fluid from patients with rheumatoid arthritis (RA) but not osteoarthritis. Accordingly, both are potential therapeutic targets in inflammatory diseases of the joints. Several LIF antagonists have been developed. They have the capacity to inhibit the biologic activities of not only LIF but also other interleukin-6 (IL-6) subfamily cytokines, including OSM. Both LIF and OSM share the same receptor, which is part of a cytokine receptor super family in which the glycoprotein 130 (gp130) subunit is a common constituent. The aim of this study was to evaluate the antagonistic potentials of two LIF mutants, LIF05 and MH35-BD. Both are mutant forms of human LIF with reduced affinity for gp130 and greater LIF receptor (LIFR) binding affinity. The results, using Ba/F3 cell proliferation assay, acute-phase protein (haptoglobin) induction analysis in HepG2 human hepatoma cells, a porcine cartilage glycosaminoglycan release assessment for proteoglycan degradation, and a collagen release assay, show that these antagonists inhibit relevant LIF, OSM, and other IL-6 subfamily cytokines in vitro albeit with differential potencies and have, therefore, therapeutic potential for treatment of RA and perhaps other diseases.

Generation of mutant leukaemia inhibitory factor (LIF)-IgG heavy chain fusion proteins as bivalent antagonists of LIF.

Two leukaemia inhibitory factor (LIF) mutants, designated MH35-BD and LIF05, have been shown to have a capacity to inhibit the biological activities of not only human LIF (hLIF) but also other interleukin-6 (IL-6) subfamily cytokines such as human oncostatin M (hOSM). These cytokines share the same receptor complex in which the glycoprotein 130 (gp130) subunit is a common constituent. However, at low concentrations and in their monomeric forms, such molecules have a relatively short plasma half-life due to rapid clearance from the kidneys. Here, to prolong their serum half-lives, we have used a multi-step polymerase chain reaction (PCR) to fuse each of the LIF05 and MH35-BD cDNA fragments to a sequence encoding the Fc portion, and the hinge region, of the human immunoglobulin G (hIgG) heavy chain. The linking was achieved through an oligomer encoding a thrombin-sensitive peptide linker thus generating MH35-BD:Fc and LIF05:Fc, respectively. Both Fc fusion constructs were expressed in insect cell Sf21 and the proteins were purified by two successive affinity chromatography steps using nickel-nitrilotriacetic acid (Ni-NTA) agarose and protein A beads. The Ba/F3 cell-based proliferation assay was used to confirm that the proteins were biologically active. In addition, preliminary pharmacokinetics indicates that the Fc fusion constructs have a longer serum half-life compared to their non-fusion counterparts.

A suicidal strain of Listeria monocytogenes is effective as a DNA vaccine delivery system for oral administration.

In this study we determined the in vivo activity of model ovalbumin vaccines delivered by direct intramuscular delivery of plasmid DNA or oral delivery using a recombinant suicidal Listeria monocytogenes strain (rsΔ2). In a previous report we described how rsΔ2 is capable of delivering luciferase, as protein or DNA, in vitro, into non-dividing intestinal epithelial cells (Kuo et al., 2009). This is achieved by engineering a dual expression shuttle vector, pDuLX-Luc, that replicates in E. coli and rsΔ2 and drives gene expression from the Listeria promoter (Phly) as well as the eukaryotic cytomegalovirus promoter (CMV), thereby delivering both protein and plasmid DNA to the cell cytoplasm. For the current in vivo study rsΔ2 containing pDuLX-OVA was used to deliver both ovalbumin protein and the mammalian expression plasmid by the oral route. Controls were used to investigate the activity of this system versus positive and negative controls, as well as quantifying activity against direct intramuscular injection of expression plasmids. Oral administration of rsΔ2(pDuLX-OVA) produced significant titres of antibody and was effective at inducing targeted T-cell lysis (approximately 30% lysis relative to an experimental positive control, intravenous OVA-coated splenocytes+lipopolysaccharide). Intramuscular injection of plasmids pDuLX-OVA or p3L-OVA (which lacks the prokaryotic promoter) also produced significant CTL-mediated cell lysis. The delivery of the negative control rsΔ2 (pDuLX-Luc) confirmed that the observed activity was induced specifically by the ovalbumin vaccination. The data suggest that the oral activity of rsΔ2(pDuLX-OVA) is explained by delivery of OVA protein, expressed in rsΔ2 from the prokaryotic promoter present in pDuLX-OVA, but transfection of mammalian cells in vivo may also play a role. Antibody titres were also produced by oral delivery (in rsΔ2) of the p3L-OVA plasmid in which does not include a prokaryotic promoter.

PGRMC1 regulation by phosphorylation: potential new insights in controlling biological activity

Progesterone receptor membrane component 1 (PGRMC1) is a multifunctional protein implicated in multiple pathologies, including cancer and Alzheimer's disease. The recently published structure of PGRMC1 revealed heme-mediated dimerization that directed the PGRMC1-dependent cytochrome P450-mediated detoxification of doxorubicin. We describe here how the PGRMC1 structure also enables important new insights into the possible regulation of PGRMC1 function by phosphorylation. Predicted regulatory interaction sites for SH2- and SH3-domain proteins are in non-structured regions that could be available to cytoplasmic enzymes. Further to the published interpretation, we suggest that phosphorylation of PGRMC1 at position Y113 may promote the attested membrane trafficking function of PGRMC1. To stimulate further experimentation, we also discuss that heme-mediated dimerization of PGRMC1 and membrane trafficking may be mutually exclusive functions. These roles could potentially be reciprocally regulated by phosphorylation/dephosphorylation at Y113. It follows that the phosphorylation status of PGRMC1 should be further explored in order to better understand many of its proposed biological functions.

Quantitative non-invasive cell characterisation and discrimination based on multispectral autofluorescence features.

Automated and unbiased methods of non-invasive cell monitoring able to deal with complex biological heterogeneity are fundamentally important for biology and medicine. Label-free cell imaging provides information about endogenous autofluorescent metabolites, enzymes and cofactors in cells. However extracting high content information from autofluorescence imaging has been hitherto impossible. Here, we quantitatively characterise cell populations in different tissue types, live or fixed, by using novel image processing and a simple multispectral upgrade of a wide-field fluorescence microscope. Our optimal discrimination approach enables statistical hypothesis testing and intuitive visualisations where previously undetectable differences become clearly apparent. Label-free classifications are validated by the analysis of Classification Determinant (CD) antigen expression. The versatility of our method is illustrated by detecting genetic mutations in cancer, non-invasive monitoring of CD90 expression, label-free tracking of stem cell differentiation, identifying stem cell subpopulations with varying functional characteristics, tissue diagnostics in diabetes, and assessing the condition of preimplantation embryos.

Caspase-3, myogenic transcription factors and cell cycle inhibitors are regulated by leukemia inhibitory factor to mediate inhibition of myogenic differentiation.

BACKGROUND: Leukemia inhibitory factor (LIF) is known to inhibit myogenic differentiation as well as to inhibit apoptosis and caspase-3 activation in non-differentiating myoblasts. In addition caspase-3 activity is required for myogenic differentiation. Therefore the aim of this study was to further investigate mechanisms of the differentiation suppressing effect of LIF in particular the possibility of a caspase-3 mediated inhibition of differentiation. RESULTS: LIF dependent inhibition of differentiation appeared to involve several mechanisms. Differentiating myoblasts that were exposed to LIF displayed increased transcripts for c-fos. Transcripts for the cell cycle inhibitor p21 as well as muscle regulatory factors myoD and myogenin were decreased with LIF exposure. However, LIF did not directly induce a proliferative effect under differentiation conditions, but did prevent the proportion of myoblasts that were proliferating from decreasing as differentiation proceeded. LIF stimulation decreased the percentage of cells positive for active caspase-3 occurring during differentiation. Both the effect of LIF inhibiting caspase-3 activation and differentiation appeared dependent on mitogen activated protein kinase and extracellular signal regulated kinase kinase (MEK) signalling. The role of LIF in myogenic differentiation was further refined to demonstrate that myoblasts are unlikely to secrete LIF endogenously. CONCLUSIONS: Altogether this study provides a more comprehensive view of the role of LIF in myogenic differentiation including LIF and receptor regulation in myoblasts and myotubes, mechanisms of inhibition of differentiation and the link between caspase-3 activation, apoptosis and myogenic differentiation.

Interleukin-6 subfamily cytokines and rheumatoid arthritis: role of antagonists.

Many cytokines have been implicated in the inflammatory pathways that characterize rheumatoid arthritis (RA) and related inflammatory diseases of the joints. These include members of the interleukin-6 (IL-6) family of cytokines, several of which have been detected in excess in the synovial fluid from RA patients. What makes the IL-6 group of cytokines a family is their common use of the glycoprotein 130 (gp130) receptor subunit, to which they bind with different affinities. Several strategies have been developed to block the pro-inflammatory activities of IL-6 subfamily cytokines. These include the application of monoclonal antibodies, the creation of mutant form(s) of the cytokine with enhanced binding affinity to gp130 receptor and the generation of antagonists by selective mutagenesis of the specific cytokine/gp130 receptor-binding site(s). The rationale for the use of anti-cytokine therapy in inflammatory joint diseases is based on evidence from studies in vitro and in vivo, which implicate major cytokines such as interleukin-1 (IL-1), tumour necrosis factor (TNF)-alpha and IL-6 in RA pathogenesis. In particular, IL-6 subfamily antagonists have a wide range of potential therapeutic and research applications. This review focuses on the role of some of the IL-6 subfamily cytokines in the pathogenesis of the inflammatory diseases of the joints (IJDs), such as RA. In addition, an overview of the recently developed antagonists will be discussed.

Targeting the glycoprotein 130 receptor subunit to control pain and inflammation.

The glycoprotein 130 (gp130) is a shared signal-transducing-membrane-associated receptor for several hematopoietic cytokines. Its activation is implicated in pain and in a variety of diseases via signaling of proinflammatory cytokines. These include interleukin-6 (IL-6) subfamily cytokines, many of which play important roles in the pathogenesis of diseases such as rheumatoid arthritis, Castleman's disease, and Kaposi's sarcoma. Several strategies have been developed to block gp130-receptor-mediated signaling. These include the application of monoclonal antibodies, the creation of mutant form(s) of the gp130 with increased binding affinity for such ligands as IL-6/sIL-6R complex, and the generation of antagonists by selective mutagenesis of the specific cytokine/gp130 receptor binding site(s). Other strategies include targeting gp130-mediated signaling pathways such as that involving signal transducer and activator of transcription-3. This review provides a summary of the latest research pertaining to the role of gp130 in the pathogenesis of inflammatory and other diseases in which the gp130 receptor is implicated. An overview of antagonists targeting the gp130 receptor is included with particular emphasis on their mechanism of action and their limitations and potential for therapeutic application.

A stably engineered, suicidal strain of listeria monocytogenes delivers protein and/or DNA to fully differentiated intestinal epithelial monolayers.

We have generated a recombinant stable, suicidal Listeria monocytogenes strain (rsDelta2) capable of delivering antigens as protein or DNA into nondividing intestinal epithelial cells. The rsDelta2 strain was generated by inserting a cell wall hydrolysin gene, "ply118" together with its associated holin gene from a Listeria-specific phage, into the attenuated L. monocytonegenes genome of strain Delta2. The hol118/ply118 gene was placed under the control of the Listeria promoter PactA, inducing bacteria to undergo autolysis in eukaryotic cells. The rsDelta2 strain had normal growth rate in rich bacterial growth medium, but its replication in eukaryotic cells was limited, and its autolysis was used to deliver its contents to the cytoplasm of eukaryotic cells. The delivery potential of rsDelta2 was explored using engineered shuttle vectors designed to facilitate expression of a transgene, either in rsDelta2 (driven by Phly) or in the mammalian cell (driven by P(CMV)), or both (using our engineered dual Listeria and mammalian expression vector, pDuLX). The luciferase reporter was used to demonstrate that pDuLX vector allowed delivery of both protein and DNA to dividing Caco-2 human epithelial cells. As expected, nondividing fully differentiated Caco-2 monolayers were resistant to transfection with Lipofectamine, which can be explained by lack of access to the cell nucleus. We demonstrated that when Caco-2 monolayers were treated with rsDelta2, the bacteria were able to deliver a significant quantity of luciferase protein. By implication the bacteria were also able to deliver DNA, but expression driven by the eukaryotic promoter in host Caco-2 cells was not observed. When the rsDelta2 strain was taken up by Caco-2 cells, there was little or no bacterial growth, whereas the control Delta2 strain was viable and grew by approximately three log cycles within the Caco-2 cells. A small mass of protein or DNA was delivered by the Delta2 strain perhaps because some bacteria died, but despite the level of growth the mass of protein delivered to dividing Caco-2 cells by the Delta2 strain was considerably less than that delivered by the rsDelta2 strain. We concluded that the Listeria delivery system has prospects for oral vaccination using antigens synthesized by the bacterium itself.

The 3'-untranslated region of p21WAF1 mRNA is a composite cis-acting sequence bound by RNA-binding proteins from breast cancer cells, including HuR and poly(C)-binding protein.

Despite promoting growth in many cell types, epidermal growth factor (EGF) induces growth inhibition in a variety of cancer cells that overexpress its receptor. The cyclin-dependent kinase inhibitor p21(WAF1) is a central component of this pathway. We found in human MDA-468 breast cancer cells that EGF up-regulates p21(WAF1) mRNA and protein, through a combination of increased mRNA stability and transcription. The decay rate of a hybrid luciferase reporter full-length p21(WAF1) 3'-untranslated region (UTR) mRNA was significantly faster than that of a control mRNA. Transfections with a variety of p21(WAF1) 3'-UTR constructs identified multiple cis-acting elements capable of reducing basal reporter activity. Short wavelength ultraviolet light induced reporter activity in constructs containing the 5' region of the p21(WAF1) 3'-UTR, whereas EGF induced reporter activity in constructs containing sequences 3' of the UVC-responsive region. These cis-elements bound multiple proteins from MDA-468 cells, including HuR and poly(C)-binding protein 1 (CP1). Immunoprecipitation studies confirmed that HuR and CP1 associate with p21(WAF1) mRNA in MDA-468 cells. Over- and underexpression of HuR in MDA-468 cells did not affect EGF-induced p21(WAF1) protein expression or growth inhibition. However, binding of HuR to its target 3'-UTR cis-element was regulated by UVC but not by EGF, suggesting that these stimuli modulate the stability of p21(WAF1) mRNA via different mechanisms. We conclude that EGF-induced p21(WAF1) protein expression is mediated largely by stabilization of p21(WAF1) mRNA elicited via multiple 3'-UTR cis-elements. Although HuR binds at least one of these elements, it does not appear to be a major modulator of p21(WAF1) expression or growth inhibition in this system. CP1 is a novel p21(WAF1) mRNA-binding protein that may function cooperatively with other mRNA-binding proteins to regulate p21(WAF1) mRNA stability.