PEDF Protects Endothelial Barrier Integrity during Acute Myocardial Infarction via 67LR.

Maintaining the integrity and protecting the stability of tight junctions in endothelial cells is a potential therapeutic strategy against myocardial ischaemia. Laminin receptors (67LR) are highly expressed on endothelial cell membranes and are associated with endothelial barrier function. Herein, we sought to demonstrate the direct effects of pigment epithelial-derived factor (PEDF) on tight junctions between endothelial cells via 67LR during acute myocardial infarction (AMI) and elucidate its underlying mechanisms. We detected that PEDF directly increased the level of the tight junction protein zonula occludens protein 1 (ZO-1) after overexpression in vitro and in vivo using Western blotting. Evans Blue/TTC staining showed that PEDF significantly reduced the size of the infarcted myocardium. Immunofluorescence and the transwell cellular experiments suggested that PEDF significantly upregulated PI3K-AKT permeability and the distribution of ZO-1 between endothelial cells under OGD conditions. Interestingly, PEDF significantly upregulated the phosphorylation levels of PI3K-AKT-mTOR under oxygen and glucose deprivation conditions but had no significant effects on the total protein expression. The protective effect of PEDF on ZO-1 was significantly inhibited following the inhibition of PI3K-AKT-mTOR. The activation of phosphorylation of PI3K-AKT-mTOR by PEDF was blocked after silencing 67LR, as were the protective effects of PEDF on ZO-1. Therefore, we have reason to believe that PEDF increased ZO-1 expression through the 67LR-dependent PI3K-AKT-mTOR signaling pathway, thus maintaining tight junction stability and protecting cardiac function.

67-kDa Laminin Receptor-Mediated Cellular Sensing System of Green Tea Polyphenol EGCG and Functional Food Pairing.

The body is equipped with a "food factor-sensing system" that senses food factors, such as polyphenols, sulfur-containing compounds, and vitamins, taken into the body, and plays an essential role in manifesting their physiological effects. For example, (-)-epigallocatechin-3-O-gallate (EGCG), the representative catechin in green tea (Camellia sinensi L.), exerts various effects, including anti-cancer, anti-inflammatory, and anti-allergic effects, when sensed by the cell surficial protein 67-kDa laminin receptor (67LR). Here, we focus on three representative effects of EGCG and provide their specific signaling mechanisms, the 67LR-mediated EGCG-sensing systems. Various components present in foods, such as eriodictyol, hesperetin, sulfide, vitamin A, and fatty acids, have been found to act on the food factor-sensing system and affect the functionality of other foods/food factors, such as green tea extract, EGCG, or its O-methylated derivative at different experimental levels, i.e., in vitro, animal models, and/or clinical trials. These phenomena are observed by increasing or decreasing the activity or expression of EGCG-sensing-related molecules. Such functional interaction between food factors is called "functional food pairing". In this review, we introduce examples of functional food pairings using EGCG.

Exploration of novel anti-angiogenic PEDF-derived peptides with improved activitives by inhibiting proliferation, suppressing migration, and inducing 67LR internalization.

Diabetic retinopathy (DR) remains high incidence and accounts for severe impact on vision in diabetics, but its mechanism is still poorly understood. Abnormal migration and proliferation of endothelial cells (ECs) drive neovascular retinopathies, which has an important role in promoting the occurrence and development of DR. In this study, we designed and synthesized a series of PEDF-derived peptides as angiogenesis inhibitors. Especially, compound G24 significantly inhibited the cell proliferation in VEGF-activated human umbilical vein endothelial cells (HUVECs) with IC50 values of 2.88 ± 0.19 µM. Further biological evaluation demonstrated that compound G24 exhibited strong inducing-effects on cell apoptosis and internalization of 67LR, and advanced inhibitory potency in cell migration and angiogenesis formed by HUVECs in vitro. In summary, the optimal compound G24 as a novel angiogenesis inhibitor showed the potentiality in the further research for the treatment for DR.

Cancer cell selective probe by mimicking EGCG.

Targeting proteins that are overexpressed in cancer cells is the major strategy of molecular imaging and drug delivery systems. The 67-kDa laminin receptor (67LR), also known as oncofetal antigen, is overexpressed in several types of cancer, including melanoma, multiple myeloma, cervical cancer and bile duct carcinoma. 67LR is involved in tumour growth, tumour metastasis and drug resistance. Green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) directly binds to cell-surface 67LR and induces apoptosis through the protein kinase B (Akt)/endothelial nitric oxide synthase/nitric oxide/cyclic GMP (cGMP) axis. Here we report the optimum hydroxyl group for the utilization of EGCG as a novel fluorescent EGCG-mimic imaging probe based on 67LR agonist characters, including Akt activation and inhibitory effect on viable cell number in cancer cells. 67LR specific targeting is unambiguously confirmed with the use of a non-labelled EGCG competitive assay and 67LR knockdown. Importantly, this probe strongly binds to multiple myeloma cells compared with its binding to normal cells.

Engineering Boron Hot Spots for the Site-Selective Installation of Iminoboronates on Peptide Chains.

Boronic acids (BAs) are a promising bioconjugation function to design dynamic materials as they can establish reversible covalent bonds with oxygen/nitrogen nucleophiles that respond to different pH, ROS, carbohydrates and glutathione levels. However, the dynamic nature of these bonds also limits the control over the stability and site-selectivity of the bioconjugation, which ultimately leads to heterogeneous conjugates with poor stability under physiological conditions. Here we disclose a new strategy to install BAs on peptide chains. In this study, a "boron hot spot" based on the 3-hydroxyquinolin-2(1H)-one scaffold was developed and upon installation on a peptide N-terminal cysteine, enables the site-selective formation of iminoboronates with 2-formyl-phenyl boronic acids (Ka of 58128±2 m-1 ). The reaction is selective in the presence of competing lysine ϵ-amino groups, and the resulting iminoboronates, displayed improved stability in buffers solutions and a cleavable profile in the presence of glutathione. Once developed, the methodology was used to prepare cleavable fluorescent conjugates with a laminin fragment, which enabled the validation of the 67LR receptor as a target to deliver cargo to cancer HT29 cells.

Inhibition of retinal neovascularization by a PEDF-derived nonapeptide in newborn mice subjected to oxygen-induced ischemic retinopathy.

Retinopathy of prematurity (ROP) is a growing cause of lifelong blindness and visual defects as improved neonatal care worldwide increases survival in very-low-birthweight preterm newborns. Advancing ROP is managed by laser surgery or a single intravitreal injection of anti-VEGF, typically at 33-36 weeks gestational age. While newer methods of scanning and telemedicine improve monitoring ROP, the above interventions are more difficult to deliver in developing countries. There is also concern as to laser-induced detachment and adverse developmental effects in newborns of anti-VEGF treatment, spurring a search for alternative means of mitigating ROP. Pigment epithelium-derived factor (PEDF), a potent angiogenesis inhibitor appears late in gestation, is undetected in 25-28 week vitreous, but present at full term. Its absence may contribute to ROP upon transition from high-to-ambient oxygen environment or with intermittent hypoxia. We recently described antiangiogenic PEDF-derived small peptides which inhibit choroidal neovascularization, and suggested that their target may be laminin receptor, 67LR. The latter has been implicated in oxygen-induced ischemic retinopathy (OIR). Here we examined the effect of a nonapeptide, PEDF 336, in a newborn mouse OIR model. Neovascularization was significantly decreased in a dose-responsive manner by single intravitreal (IVT) injections of 1.25-7.5 µg/eye (1.0-6.0 nmol/eye). By contrast, anti-mouse VEGFA164 was only effective at 25 ng/eye, with limited dose-response. Combination of anti-VEGFA164 with PEDF 336 gave only the poorer anti-VEGF response while abrogating the robust inhibition seen with peptide-alone, suggesting a need for VEGF in sensitizing the endothelium to the peptide. VEGF stimulated 67LR presentation on endothelial cells, which was decreased in the presence of PEDF 336. Mouse and rabbit eyes showed no histopathology or inflammation after IVT peptide injection. Thus, PEDF 336 is a potential ROP therapeutic, but is not expected to be beneficial in combination with anti-VEGF.

Src Mediates Epigallocatechin-3-O-Gallate-Elicited Acid Sphingomyelinase Activation.

Epigallocatechin-3-O-gallate (EGCG) is one of the major bioactive compounds known to be present in green tea. We previously reported that EGCG shows selective toxicity through activation of the protein kinase B (Akt)/cyclic guanosine monophosphate (cGMP)/acid sphingomyelinase (ASM) axis via targeting its receptor 67-kDa laminin receptor (67LR), which is overexpressed in cancer. However, little is known about upstream mechanisms of EGCG-elicited ASM activation. In this study we show that the proto-oncogene tyrosine-protein kinase Src, also known as c-src, plays a crucial role in the anticancer effect of EGCG. We showed that EGCG elicits phosphorylation of Src at Tyr 416, a crucial phosphorylation site for its activity, and that the pharmacological inhibition of Src impedes the upstream events in EGCG-induced cell death signaling including upregulation of Akt activity, increase in cGMP levels, and activation of ASM. Moreover, focal adhesion kinase (FAK), which is involved in the phosphorylation of Src, is colocalized with 67LR. EGCG treatment enhanced interaction of FAK and 67LR. Consistent with these findings, pharmacological inhibition of FAK significantly neutralized EGCG-induced upregulation of Akt activity and activation of ASM. Taken together, FAK/Src play crucial roles in the upstream signaling of EGCG.

The Synthesis of trans-Flavan-3-ol Gallates by Regioselective Oxidative Etherification and Their Cytotoxicity Mediated by 67 LR.

We report on a chiral pool approach for the synthesis of trans-flavan-3-ol gallates from epichlorohydrin. The trans-flavan-3-ol gallates were prepared by the cycloetherification of the phenol at the C2 benzylic position of 2-acylozyl-1,3-diarylpropane during regioselective C-H oxidation. The 1,3-diarylpropanes were prepared starting from epichlorohydrin by epoxide opening with A and B ring precursors, followed by acylation of the resultant alcohol with galloyl chloride. The availability of both the enantiomers of epichlorohydrin allowed the preparation of the corresponding enantiomer using the same procedure. The cytotoxicity of the compounds against U266 cells was tested, in which 5-deoxy-7,3'-O-dimethyl gallocatechin gallate exhibited cytotoxicity that was more than ten times stronger than natural (-)-EGCG. In addition, the absolute configuration of the derivatives did not critically affect the biological activity.

Epigallocatechin-3-Gallate Attenuates Leukocyte Infiltration in 67-kDa Laminin Receptor-Dependent and -Independent Pathways in the Rat Frontoparietal Cortex following Status Epilepticus.

Status epilepticus (SE) evokes leukocyte infiltration in the frontoparietal cortex (FPC) without the blood-brain barrier disruption. Monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) regulate leukocyte recruitments into the brain parenchyma. Epigallocatechin-3-gallate (EGCG) is an antioxidant and a ligand for non-integrin 67-kDa laminin receptor (67LR). However, it is unknown whether EGCG and/or 67LR affect SE-induced leukocyte infiltrations in the FPC. In the present study, SE infiltrated myeloperoxidase (MPO)-positive neutrophils, as well as cluster of differentiation 68 (CD68)-positive monocytes in the FPC are investigated. Following SE, MCP-1 was upregulated in microglia, which was abrogated by EGCG treatment. The C-C motif chemokine receptor 2 (CCR2, MCP-1 receptor) and MIP-2 expressions were increased in astrocytes, which were attenuated by MCP-1 neutralization and EGCG treatment. SE reduced 67LR expression in astrocytes, but not endothelial cells. Under physiological conditions, 67LR neutralization did not lead to MCP-1 induction in microglia. However, it induced MIP-2 expression and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in astrocytes and leukocyte infiltration in the FPC. Co-treatment of EGCG or U0126 (an ERK1/2 inhibitor) attenuated these events induced by 67LR neutralization. These findings indicate that the EGCG may ameliorate leukocyte infiltration in the FPC by inhibiting microglial MCP-1 induction independent of 67LR, as well as 67LR-ERK1/2-MIP-2 signaling pathway in astrocytes.

Laminin Receptor-Mediated Nanoparticle Uptake by Tumor Cells: Interplay of Epigallocatechin Gallate and Magnetic Force at Nano-Bio Interface.

Epigallocatechin gallate (EGCG), a major tea catechin, enhances cellular uptake of magnetic nanoparticles (MNPs), but the mechanism remains unclear. Since EGCG may interact with the 67-kDa laminin receptor (67LR) and epidermal growth factor receptor (EGFR), we investigate whether a receptor and its downstream signaling may mediate EGCG's enhancement effects on nanoparticle uptake. As measured using a colorimetric iron assay, EGCG induced a concentration-dependent enhancement effect of MNP internalization by LN-229 glioma cells, which was synergistically enhanced by the application of a magnetic field. Transmission electron microscopy demonstrated that EGCG increased the number, but not the size, of internalized vesicles, whereas EGCG and the magnet synergistically increased the size of vesicles. EGCG appears to enhance particle-particle interaction and thus aggregation following a 5-min magnet application. An antibody against 67LR, knockdown of 67LR, and a 67LR peptide (amino acid 161-170 of 67LR) attenuated EGCG-induced MNP uptake by 35%, 100%, and 45%, respectively, suggesting a crucial role of 67LR in the effects of EGCG. Heparin, the 67LR-binding glycosaminoglycan, attenuated EGCG-induced MNP uptake in the absence, but not presence, of the magnet. Such enhancement effects of EGCG were attenuated by LY294002 (a phosphoinositide 3-kinase inhibitor) and Akt inhibitor, but not by agents affecting cGMP levels, suggesting potential involvement of signaling downstream of 67LR. In contrast, the antibody against EGFR exerted no effect on EGCG-enhanced internalization. These results suggest that 67LR may be potentially amenable to tumor-targeted therapeutics.

Epigallocatechine-3-gallate Inhibits the Adipogenesis of Human Mesenchymal Stem Cells via the Regulation of Protein Phosphatase-2A and Myosin Phosphatase.

Epigallocatechin-3-gallate (EGCG) has widespread effects on adipocyte development. However, the molecular mechanisms of EGCG are not fully understood. We investigate the adipogenic differentiation of human-derived mesenchymal stem cells, including lipid deposition and changes in the expression and phosphorylation of key transcription factors, myosin, protein phosphatase-2A (PP2A), and myosin phosphatase (MP). On day 6 of adipogenic differentiation, EGCG (1-20 µM) suppressed lipid droplet formation, which was counteracted by an EGCG-binding peptide for the 67 kDa laminin receptor (67LR), suggesting that EGCG acts via 67LR. EGCG decreased the phosphorylation of CCAAT-enhancer-binding protein beta via the activation of PP2A in a protein kinase A (PKA)-dependent manner, leading to the partial suppression of peroxisome proliferator-activated receptor gamma (PPARγ) and adiponectin expression. Differentiated cells exhibited a rounded shape, cortical actin filaments, and lipid accumulation. The EGCG treatment induced cell elongation, stress fiber formation, and less lipid accumulation. These effects were accompanied by the degradation of the MP target subunit-1 and increased the phosphorylation of the 20 kDa myosin light chain. Our results suggest that EGCG acts as an agonist of 67LR to inhibit adipogenesis via the activation of PP2A and suppression of MP. These events are coupled with the decreased phosphorylation and expression levels of adipogenic transcription factors and changes in cell shape, culminating in curtailed adipogenesis.

EGCG down-regulates MuRF1 expression through 67-kDa laminin receptor and the receptor signaling is amplified by eriodictyol.

(-)-epigallocatechin-3-O-gallate (EGCG) is a bioactive polyphenol in green tea. Previous studies have demonstrated the beneficial effects of EGCG on muscle mass and muscle atrophy. In the current study, we investigated the mechanisms underlying effect of EGCG on muscle atrophy. It was demonstrated that EGCG suppressed muscle-specific ubiquitin ligase, muscle RING Finger 1 (MuRF1) expression through 67-kDa laminin receptor (67LR). Previous studies have shown that eriodictyol potentiates the anti-tumor activities of EGCG by amplifying 67LR signaling. Therefore, we investigated the effects of EGCG and eriodictyol on the MuRF1 expression in C2C12 myotubes. The combined treatment of EGCG and eriodictyol significantly suppressed MuRF1 expression in dexamethasone-treated C2C12 myotubes. Tail suspension was maintained for 10 consecutive days using C57BL6/J mice, and during this time EGCG and eriodictyol were orally administered. In the gastrocnemius muscle, the muscle mass loss was inhibited by the combination of EGCG and eriodictyol. Therefore, EGCG may prevent muscle atrophy by inducing 67LR signaling and eriodictyol amplifies this pathway.

Lysines residing in putative Small Ubiquitin-like MOdifier (SUMO) motifs regulate fate and function of 37 KDa laminin receptor.

There is a putative precursor to mature receptor relationship between 37 Laminin Receptor (LR) and 67 LR. As such, the pair are frequently referred to as a single entity, the 37/67 kDa Laminin Receptor (37/67 LR) and 67 LR was identified as a laminin binding entity. 37/67 LR has been of clinical interest for many years, as 37/67 LR is a prognostic indicator for many cancers including breast, lung, colon, and prostate. However, the genesis of 67 LR is controversial, and confounded by its stability under SDS-PAGE conditions, a lack of splice variants, and the existence of post-translational modifications that cannot account for the mass discrepancy between 37 and 67 LR. In the present work, we mutated potential SUMO motif sites (Lysine residues) in 37 LR and generated a series of 37 LR-expressing plasmids with a C-terminal histidine tag. We report an inability to detect 67 LR formation, suggesting that SUMOylation does not appear to directly occur at the lysine residues proposed. However, the work revealed that these lysine mutations still appear to be important and can impact the fate and function of 37 LR, by impairing half-life and steady state pre-mRNA levels. These results suggest that the Lys residues within putative SUMO motifs of 37 LR are important for 37 LR function.

Coptisine Induces Apoptosis in Human Hepatoma Cells Through Activating 67-kDa Laminin Receptor/cGMP Signaling.

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver. Hence, new anti-liver cancer treatment strategies need to be urgently developed. Coptisine is a natural alkaloid extracted from rhizoma coptidis which exhibits anticancer activity in various preclinical models, including liver cancer. However, the molecular mechanisms underlying the anti-liver cancer effects of coptisine remains unclear. We used flow cytometry to assess the binding of coptisine to 67LR expressed on the surface of SMMC7721, HepG2, LO2 and H9 cells. Then SMMC7721, HepG2 and BEL7402 cells, belonging to the HCC cell lines, were treated with coptisine. The cell viability was detected using a cell counting kit-8 assay. Apoptosis was evaluated using flow cytometry and transferase-mediated dUTP nick-end labeling (TUNEL) assay. Apoptotic-related proteins and tumor death receptor 67-kDa laminin receptor (67LR) were detected using Western blot analysis. The cyclic guanosine 3',5'-monophosphate (cGMP) concentration was determined using enzyme-linked immunosorbent assay. sh67LR lentivirus, anti67LR antibody, and cGMP inhibitor NS2028 were used to determine how a 67LR/cGMP signaling pathway regulated coptisine-induced apoptosis. Tumor growth inhibited by coptisine was confirmed in a SMMC7721 cell xenograft mouse model. Coptisine selectively exhibited cell viability in human hepatoma cells but not in normal human hepatocyte cell line LO2 cells. Coptisine promoted SMMC7721 and HepG2 cell apoptosis by increasing 67LR activity. Both 67LR antibody and sh67LR treatment blocked coptisine-induced apoptosis and inhibition of cell viability. Coptisine upregulated the expression of cGMP. Moreover, cGMP inhibitor NS2028 significantly decreased coptisine-induced apoptosis and inhibition of cell viability. In vivo experiments confirmed that coptisine could significantly suppress the tumor growth and induce apoptosis in SMMC7721 xenografts through a 67LR/cGMP pathway. Coptisine-mediated 67LR activation may be a new therapeutic strategy for treating hepatic malignancy.

Molecular Targets of Epigallocatechin-Gallate (EGCG): A Special Focus on Signal Transduction and Cancer.

Green tea is a beverage that is widely consumed worldwide and is believed to exert effects on different diseases, including cancer. The major components of green tea are catechins, a family of polyphenols. Among them, epigallocatechin-gallate (EGCG) is the most abundant and biologically active. EGCG is widely studied for its anti-cancer properties. However, the cellular and molecular mechanisms explaining its action have not been completely understood, yet. EGCG is effective in vivo at micromolar concentrations, suggesting that its action is mediated by interaction with specific targets that are involved in the regulation of crucial steps of cell proliferation, survival, and metastatic spread. Recently, several proteins have been identified as EGCG direct interactors. Among them, the trans-membrane receptor 67LR has been identified as a high affinity EGCG receptor. 67LR is a master regulator of many pathways affecting cell proliferation or apoptosis, also regulating cancer stem cells (CSCs) activity. EGCG was also found to be interacting directly with Pin1, TGFR-II, and metalloproteinases (MMPs) (mainly MMP2 and MMP9), which respectively regulate EGCG-dependent inhibition of NF-kB, epithelial-mesenchimal transaction (EMT) and cellular invasion. EGCG interacts with DNA methyltransferases (DNMTs) and histone deacetylases (HDACs), which modulates epigenetic changes. The bulk of this novel knowledge provides information about the mechanisms of action of EGCG and may explain its onco-suppressive function. The identification of crucial signalling pathways that are related to cancer onset and progression whose master regulators interacts with EGCG may disclose intriguing pharmacological targets, and eventually lead to novel combined treatments in which EGCG acts synergistically with known drugs.

Improving the Anticancer Efficacy of Laminin Receptor-Specific Therapeutic Ruthenium Nanoparticles (RuBB-Loaded EGCG-RuNPs) via ROS-Dependent Apoptosis in SMMC-7721 Cells.

Functionalization can promote the uptake of nanoparticles into cancer cells via receptor-mediated endocytosis, enabling them to exert their therapeutic effects. In this paper, epigallocatechin gallate (EGCG), which has a high binding affinity to 67 kDa laminin receptor (67LR) overexpressed in HCC cells, was employed in the present study to functionalized ruthenium nanoparticles (RuNPs) loaded with luminescent ruthenium complexes to achieve antiliver cancer efficacy. [Ru(bpy)2(4-B)] (ClO4)2·2H2O (RuBB)-loaded EGCG-RuNPs (bpy = 2,2'-bipyridine) showed small particle size with narrow distribution, better stability, and high selectivity between liver cancer and normal cells. The internalization of RuBB-loaded EGCG-RuNPs was inhibited by 67LR-blocking antibody or laminin, suggesting that 67LR-mediated endocytosis played an important role in the uptake into HCC cells. Moreover, transmission electron microscopy and confocal microscopic images showed that RuBB-loaded EGCG-RuNPs accumulated in the cytoplasm of SMMC-7721 cells. Furthermore, our results indicated that the EGCG-functionalized nanoparticles displayed enhanced anticancer effects in a target-specific manner. Concentrations of RuBB-loaded EGCG-RuNPs, nontoxic in normal L-02 cells, showed direct reactive oxygen species-dependent cytotoxic, pro-apoptotic, and anti-invasive effects in SMMC-7721 cells. Furthermore, in vivo animal study demonstrated that RuBB-loaded EGCG-RuNPs possessed high antitumor efficacy on tumor-bearing nude mice. It is encouraging to conclude that the multifunctional RuNPs may form the basis of new strategies on the treatment of liver cancer and other malignancies.

Looking into laminin receptor: critical discussion regarding the non-integrin 37/67-kDa laminin receptor/RPSA protein.

The 37/67-kDa laminin receptor (LAMR/RPSA) was originally identified as a 67-kDa binding protein for laminin, an extracellular matrix glycoprotein that provides cellular adhesion to the basement membrane. LAMR has evolutionary origins, however, as a 37-kDa RPS2 family ribosomal component. Expressed in all domains of life, RPS2 proteins have been shown to have remarkably diverse physiological roles that vary across species. Contributing to laminin binding, ribosome biogenesis, cytoskeletal organization, and nuclear functions, this protein governs critical cellular processes including growth, survival, migration, protein synthesis, development, and differentiation. Unsurprisingly given its purview, LAMR has been associated with metastatic cancer, neurodegenerative disease and developmental abnormalities. Functioning in a receptor capacity, this protein also confers susceptibility to bacterial and viral infection. LAMR is clearly a molecule of consequence in human disease, directly mediating pathological events that make it a prime target for therapeutic interventions. Despite decades of research, there are still a large number of open questions regarding the cellular biology of LAMR, the nature of its ability to bind laminin, the function of its intrinsically disordered C-terminal region and its conversion from 37 to 67 kDa. This review attempts to convey an in-depth description of the complexity surrounding this multifaceted protein across functional, structural and pathological aspects.

Deciphering the complex three-way interaction between the non-integrin laminin receptor, galectin-3 and Neisseria meningitidis.

The non-integrin laminin receptor (LAMR1/RPSA) and galectin-3 (Gal-3) are multi-functional host molecules with roles in diverse pathological processes, particularly of infectious or oncogenic origins. Using bimolecular fluorescence complementation and confocal imaging, we demonstrate that the two proteins homo- and heterodimerize, and that each isotype forms a distinct cell surface population. We present evidence that the 37 kDa form of LAMR1 (37LRP) is the precursor of the previously described 67 kDa laminin receptor (67LR), whereas the heterodimer represents an entity that is distinct from this molecule. Site-directed mutagenesis confirmed that the single cysteine (C(173)) of Gal-3 or lysine (K(166)) of LAMR1 are critical for heterodimerization. Recombinant Gal-3, expressed in normally Gal-3-deficient N2a cells, dimerized with endogenous LAMR1 and led to a significantly increased number of internalized bacteria (Neisseria meningitidis), confirming the role of Gal-3 in bacterial invasion. Contact-dependent cross-linking determined that, in common with LAMR1, Gal-3 binds the meningococcal secretin PilQ, in addition to the major pilin PilE. This study adds significant new mechanistic insights into the bacterial-host cell interaction by clarifying the nature, role and bacterial ligands of LAMR1 and Gal-3 isotypes during colonization.

Phosphodiesterase 5 inhibitor acts as a potent agent sensitizing acute myeloid leukemia cells to 67-kDa laminin receptor-dependent apoptosis.

(-)-Epigallocatechin-3-O-gallate (EGCG), a polyphenol in green tea, induces apoptosis in acute myeloid leukemia (AML) cells without affecting normal cells. In this study, we observed that cGMP acts as a cell death mediator of the EGCG-induced anti-AML effect through acid sphingomyelinase activation. EGCG activated the Akt/eNOS axis, a well-known mechanism in vascular cGMP upregulation. We also observed that a major cGMP negative regulator, phosphodiesterase 5, was overexpressed in AML cells, and PDE5 inhibitor, an anti-erectile dysfunction drug, synergistically enhanced the anti-AML effect of EGCG. This combination regimen killed AML cells via overexpressed 67-kDa laminin receptors.

Retinoic acid incubation effect on proliferation of U251 cell line and effect on MAPK signal pathway / 中国生化药物杂志

Objective To investigate the retinoic acid incubation effect on proliferation of U251 cell line and effect on MAPK signal pathway. Methods ATRA solution of different concentration on the U25 1 glioma cells were incubated,the influence of ATRA on the proliferation of U25 1 cells were detected,and the proteins of MKPs and MAPK signaling pathways were detected by qRT-PCR and Western blot.Using Graph Prism 5 software for quantitative analysis of experimental results.Results Compared with control group,ATRA could effectively inhibit the proliferation of U25 1 glioma cells, in a concentration dependent manner.QRT-PCR results showed that,different concentrations of ATRA after incubation for 48 hours,the expression of MKPs mRNA changed,but the changes of MKP-5 and expression of 67LR was different,explained the main differences between the two methods of the MAPK signaling pathway was the regulation of MKP-5.Western blot results showed that the ATRA,after 48 hours of incubation,the protein MAPK pathway had changed in phosphorylation, which showed that ATRA protein in the MAPK signaling pathway through control of the degree of phosphorylation on U25 1 cell line regulation.Conclusion Retinoic acid and retinoic acid receptor play its physiological effects and regulate human glioma cell line U25 1 proliferation through different combination.Retinoic acid could not only reduce the expression of phosphorylated ERK1/2 to inhibit tumor proliferation,but also regulate three kinds of protein phosphorylation,therefore its mechanism will be more complex,at the same time that the MAPK signaling pathway plays a crucial role in tumor proliferation process.