Laminin Receptor 1 Research Articles

LAMR1 restricts Zika virus infection by attenuating the envelope protein ubiquitination

ABSTRACT Zika virus (ZIKV) infection can cause severe neurological disorders, including Guillain–Barre syndrome and meningoencephalitis in adults and microcephaly in fetuses. Here, we reveal that laminin receptor 1 (LAMR1) is a novel host resistance factor against ZIKV infection. Mechanistically, we found that LAMR1 binds to ZIKV envelope (E) protein via its intracellular region and attenuates E protein ubiquitination through recruiting the deubiquitinase eukaryotic translation initiation factor 3 subunit 5 (EIF3S5). We further found that the conserved G282 residue of E protein is essential for its interaction with LAMR1. Moreover, a G282A substitution abolished the binding of E protein to LAMR1 and inhibited LAMR1-mediated E protein deubiquitination. Together, our results indicated that LAMR1 represses ZIKV infection through binding to E protein and attenuating its ubiquitination.

Effect of Novel Molecules Against Inflammation in Lipopolysaccharide (LPS)‐Stimulated Fibroblast‐Like Synoviocytes (FLS)

Arthritis refers to a joint disorder which features inflammation of one or more joints within the body, often resulting in pain, stiffness, swelling and decreased range of motion of joints. There are two main forms of arthritis—osteoarthritis (OA) and rheumatoid arthritis (RA)—and they both cause damage to the joints in different ways. OA, the most common form of arthritis, entails the wearing away of the cartilage that protects the bones in joint spaces and RA involves the immune system attacking the synovial lining of the joints. The disease process of all forms of arthritis can cause permanent joint damage and there are limited treatments to reverse its physical changes, making it essential to gain an understanding of the general pathology of arthritis. The pathogenesis of arthritis is complex, and includes many cell types, but an inflammatory reaction is a common characteristic and has been studied extensively with various forms of arthritis. A specialized cell type, fibroblast‐like synoviocytes (FLS) in the synovial intimal lining of the joint, have been shown to play a crucial role in the pathogenesis of chronic inflammatory diseases, such as arthritis, as they produce pro‐inflammatory cytokines and cartilage‐degrading mediators. In our recent research, the inflammation activity of FLS have been characterized in vitro via the stimulation of lipopolysaccharide (LPS) for a fixed quantity of time, in this case 6 hours, and then analyzing the effect of LPS on the expression of genes representing acute inflammation in FLS, such as interleukin (IL)‐1β, IL‐6, tumor necrosis factor α (TNF‐α), and matrix metalloproteinases (MMPs). It has been shown that the gene expression of IL‐6 is an ideal marker of pro‐inflammatory activity of FLS. Beyond understanding the pro‐inflammatory responses of FLS, novel compounds have been utilized in our laboratory to counteract the stimuli of LPS, which results in FLS expressing an anti‐inflammatory response. One configuration of the novel compounds were synthesized to mimic the interaction region between Pigment Epithelium Derived Factor (PEDF) and its receptor Laminin Receptor 1 (LAMR1) and the other consists of the activity of IL‐27, which both have promising anti‐inflammatory effects on FLS at low dosages. The overall aim of this study is to investigate the effect of the novel molecules against inflammation in lipopolysaccharide (LPS)–stimulated fibroblast‐like synoviocytes (FLS) by analyzing the expression of various pro‐inflammatory cytokines and cartilage degrading mediators. In future directions of the study, second generation molecules are to be developed to enhance drug affinity and to lower the effective dosage amount, making the molecules better‐suited for clinical translation, which would be later used as a therapeutic method that would control the inflammation activity of FLS and repair the cartilage in the joint undergoing a form of arthritis.Support or Funding InformationWe acknowledge support from NIH‐1R01AR069079 (MLF).

Effect of Human Umbilical Cord Mesenchymal Stem Cell Transplantation in a Rat Model of Preeclampsia.

To test the effects of human umbilical cord mesenchymal stem cell (HU-MSC) transplantation on reversing preeclampsia (PE) symptoms in a lipopolysaccharide (LPS)-induced rat PE model. Human umbilical cord MSCs were detected, isolated, and cultured. Human umbilical cord MSC transplantation was conducted. Expressions of inflammatory cytokines in serum and placental tissue were measured by enzyme-linked immunosorbent assay. Changes in inflammatory cytokines, peroxisome proliferator-activated receptor γ (PPARγ), laminin receptor 1 (LR1), matrix metalloproteinase (MMP) 2, and MMP-9 messenger RNA (mRNA) levels in placental tissue were recorded by quantitative real-time polymerase chain reaction. Immunohistochemistry and Western blotting were performed for PPARγ detection. The LPS group exhibited increased blood pressure and proteinuria and decreased fetal weight compared to the normal pregnancy (NP) group (all P < .05). The LPS + MSC group presented lowered blood pressure and higher fetal weight than the LPS group (P < .05). The levels of interferon γ, tumor necrosis factor α (TNF-α), interleukin (IL) 1β, IL-6, IL-8, IL-12, and intercellular adhesion molecule 1 (ICAM-1) increased and the levels of IL-4 and IL-10 levels decreased in the LPS group compared to the NP group (all P < .05). Tumor necrosis factor α, IL-6, IL-12, and ICAM-1 levels decreased and IL-10 level increased in the LPS + MSC group compared to the LPS group (all P < .05). The LPS-MSC group showed lower mRNA expressions of TNF-α, IL-6, MMP-2, MMP-9, and ICAM-1 and higher mRNA expressions of IL-10, PPARγ, and LR1 than the LPS group (all P < .05). In summary, HU-MSC transplantation may be extremely beneficial for PE therapy.

High-glucose levels and elastin degradation products accelerate osteogenesis in vascular smooth muscle cells

Diabetes mellitus (DM) is a chronic disease in which the body either does not use or produce the glucose metabolising hormone insulin efficiently. Calcification of elastin in the arteries of diabetics is a major predictor of cardiovascular diseases. It has been previously shown that elastin degradation products work synergistically with transforming growth factor-beta 1 (TGF-β1) to induce osteogenesis in vascular smooth muscle cells. In this study, we tested the hypothesis that high concentration of glucose coupled with elastin degradation products and TGF-β1 (a cytokine commonly associated with diabetes) will cause a greater degree of osteogenesis compared to normal vascular cells. Thus, the goal of this study was to analyse the effects of high concentration of glucose, elastin peptides and TGF-β1 on bone-specific markers like alkaline phosphatase (ALP), osteocalcin (OCN) and runt-related transcription factor 2 (RUNX2). We demonstrated using relative gene expression and specific protein assays that elastin degradation products in the presence of high glucose cause the increase in expression of the specific elastin-laminin receptor-1 (ELR-1) and activin receptor-like kinase-5 (ALK-5) present on the surface of the vascular cells, in turn leading to overexpression of typical osteogenic markers like ALP, OCN and RUNX2. Conversely, blocking of ELR-1 and ALK-5 strongly suppressed the expression of the osteogenic proteins. In conclusion, our results indicate that glucose plays an important role in amplifying the osteogenesis induced by elastin peptides and TGF-β1, possibly by activating the ELR-1 and ALK-5 signalling pathways.

RNA interference-mediated silencing of laminin receptor 1 (LR1) suppresses migration and invasion and down-regulates matrix metalloproteinase (MMP)-2 and MMP-9 in trophoblast cells: implication in the pathogenesis of preeclampsia

Shallow trophoblast invasion is a common pathological feature of preeclampsia. The 67 kDa laminin receptor 1 (LR1) is a laminin-binding protein that has been reported to be down-regulated in preeclamptic placentas. The aim of the present study was to determine the functional role of LR1 in the migration and invasion of the trophoblast cell line, JEG3 cells. RNA interference mediated by plasmid expressing LR1 short hairpin RNA (shRNA) was utilized to knockdown LR1 expression in JEG3 cells. We found that the mRNA and protein expression levels of LR1 were significantly reduced in LR1-specific shRNA transfected cells compared with the untransfected and control shRNA transfected cells. The wound healing and Transwell invasion assays demonstrated that LR1 knockdown remarkably suppressed the migration and invasion potential of JEG3 cells. The gelatin zymography assay showed that LR1 knockdown greatly reduced matrix metalloproteinase (MMP)-2 and MMP-9 activities in the culture supernatants. Western blot analysis showed that LR1 shRNA significantly decreased expression levels of MMP-2, MMP-9 and phospho-extracellular signal-regulated kinase, but increased expression levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in comparison to the control vector-transfected cells. In conclusion, our data support an important role for LR1 in regulating trophoblast invasion and migration, and suggest a possible pathological mechanism of preeclampsia.

Laminin-111 Stimulates Proliferation of Mouse Embryonic Stem Cells Through a Reduction of Gap Junctional Intercellular Communication via RhoA-Mediated Cx43 Phosphorylation and Dissociation of Cx43/ZO-1/Drebrin Complex

Gap junctions within extracellular matrix (ECM)-defined boundaries ensure synchronous activity between cells destined to become functional mediators that regulate cell behavior. However, the role of ECM in connexin (Cx) function in mouse embryonic stem cells (mESCs) has not been elucidated. Therefore, we examined the role of laminin-111 in the control of Cx43 functions and related signal pathways in mESCs. ECM components (laminin-111, fibronectin, and collagen I) increased Cx43 phosphorylation and decreased Lucifer yellow (Ly) diffusion. In addition, laminin-111 increased the proliferation index through reduction of gap junctional intercellular communication (GJIC), which was confirmed by 18α-glycyrrhetinic acid (18α-GA). Laminin-111 increased phosphorylation of focal adhesion kinase (FAK)/Src and protein kinase C (PKC), which were inhibited by integrin β1 antibody (Ab) and laminin receptor-1 (LR-1) Ab, respectively. In addition, inhibition of both FAK/Src and PKC blocked Cx43 phosphorylation. Laminin-111 increased the Ras homolog gene family, member A (RhoA) activation, which was blocked by FAK/Src and PKC inhibitors, suggesting the existence of parallel pathways that merge at RhoA. Inhibition of RhoA reversed the laminin-111-induced increase of Cx43 phosphorylation and reduction of GJIC. Laminin-111 also stimulated the dissociation of Cx43/ZO-1 complex followed by disruption of Cx43/drebrin and Cx43/F-actin complexes, which were reversed by C3 (RhoA inhibitor). ZO-1 small interfering (si) RNA significantly decreased Ly diffusion. Moreover, laminin-111 decreased Cx43 labeling at the intercellular junction, whereas pretreatment with degradation inhibitors (lysosomal protease inhibitor, chloroquine; proteasome inhibitor, lactacystin) increased Cx43 expression, reversely. In conclusion, laminin-111 stimulated mESC proliferation through a reduction of GJIC via RhoA-mediated Cx43 phosphorylation and Cx43/ZO-1/drebrin complex instability-mediated Cx43 degradation.

Expression of laminin receptor 1 in human placentas from normal and preeclamptic pregnancies and its relationship with the severity of preeclampsia

To investigate the expression of laminin receptor 1 (LR1), a non-integrin-type laminin receptor, in preeclamptic and normal third-trimester placentas, as well as to investigate whether its expression differs with disease severity. Third trimester placental samples obtained from deliveries of preeclamptic (n=34) and normotensive healthy pregnant women (n=35) were immunohistochemically studied for the expression of LR1. The placentas from both mild (n=14) and severe (n=20) preeclamptic pregnancies were further assessed for strength of LR1 expression according to disease severity. When compared with normal placentas, the staining with LR1 protein in cytotrophoblasts and syncytiotrophoblasts was lower in preeclamptic placentas (P<0.05 and P<0.01, respectively). The intensity of staining with LR1 in decidual cells, cytotrophoblasts, syncytiotrophoblasts, and extracellular matrix cells of preeclamptic placentas did not vary with disease severity (P>0.05). Decreased LR1 expression in cytotrophoblasts and syncytiotrophoblasts of preeclamptic placentas, which may be independent of disease severity, might have a role in shallow trophoblastic invasion in preeclampsia.

Approaching Biomarkers of Membranous Nephropathy from a Murine Model to Human Disease

Background. Membranous glomerulonephropathy (MN) is the most prevalent cause of nephrotic syndrome in adult humans. However, the specific biomarkers of MN have not been fully elucidated. We examined the alterations in gene expression associated with the development of MN. Methods. Murine MN was induced by cationic bovine serum albumin (cBSA). After full-blown MN, cDNA microarray analysis was performed to identify gene expression changes, and highly expressed genes were evaluated as markers both in mice and human kidney samples. Results. MN mice revealed clinical proteinuria and the characteristic diffuse thickening of the glomerular basement membrane. There were 175 genes with significantly different expressions in the MN kidneys compared with the normal kidneys. Four genes, metallothionein-1 (Mt1), cathepsin D (CtsD), lymphocyte 6 antigen complex (Ly6), and laminin receptor-1 (Lamr1), were chosen and quantified. Mt1 was detected mainly in tubules, Lamr1 was highly expressed in glomeruli, and CtsD was detected both in tubules and glomeruli. The high expressions of Lamr1 and CtsD were also confirmed in human kidney biopsies. Conclusion. The murine MN model resembled the clinical and pathological features of human MN and may provide a tool for investigating MN. Applying cDNA microarray analysis may help to identify biomarkers for human MN.

Laminin regulates mouse embryonic stem cell migration: involvement of Epac1/Rap1 and Rac1/cdc42

Laminin is the first extracellular matrix (ECM) component to be expressed in the developing mammalian embryo. However, the roles of laminin or the related signal pathways are not well known in mouse embryonic stem cells (mESCs). Presently, we examined the effect of laminin on mESC migration. Laminin (10 microg/ml) decreased cell aggregation, whereas migration was increased. Laminin bound alpha6beta1 integrin and laminin receptor 1 (LR1), decreasing their mRNA levels. Laminin increased focal adhesion kinase (FAK) and paxillin phosphorylation, cAMP intracellular concentration, and the protein levels of exchange factor directly activated by cAMP (Epac1) and Rap1. These increases were completely blocked by alpha6beta1 integrin and LR1 neutralizing antibody, indicating that laminin-bound LR1 assists laminin-induced alpha6beta1 integrin activity and initiates signal. As a downstream signal molecule, laminin activated small G protein such as Rac1/cdc42 and its effector protein p21-activated kinase (PAK). Subsequently, laminin stimulated E-cadherin complex disruption. Inhibition of each pathway such as those for alpha6beta1 integrin and LR1, FAK, Rap1, and PAK1 blocked laminin-induced migration. We conclude that laminin binds both alpha6beta1 integrin and LR1 and induces signaling FAK/paxillin and cAMP/Epac1/Rap1. These signaling merge at Rac1/cdc42 subsequently activate PAK1. Activated PAK1 enhances E-cadherin complex disruption and finally increases mESCs migration.

Conformationally Constrained Mimetics of Laminin Peptide YIGSR as Precursors for Antimetastatic Disintegrins

Conformationally constrained mimetics of the laminin cell-adhesion site, YIGSR, are described. The site is the natural antagonist of the integrin-associated laminin receptor 1 (LAMR1) known to mediate metastatic tumor adhesion. The attachment of selected metastatic cell lines toward the constrained antagonists has been assessed. Observed differential responses prompted by folding preferences of the mimetics revealed stronger attachment activities for turnlike structures. The results permit the conformational design of antimetastatic disintegrins.

The mechanism of inhibition of metastasis by cartilage polysaccharide in breast‐cancer cells

As large amounts of porcine cartilage are discarded as waste in daily life, it is necessary to find new uses for them. We extracted polysaccharide from cartilage and performed in vitro and in vivo experiments in cancer cells. A mouse breast-cancer pulmonary metastasis model was set up, and we tried to determine the mechanism of the inhibition of metastasis by cartilage PS (polysaccharide). Effects on tumour size and the progression of metastasis indicated that cartilage PS can obviously inhibit metastasis in breast-cancer cells. The levels of LNR1 (laminin receptor 1), alphavbeta3 integrin and MMP-9 (matrix metalloproteinase-9) in mice treated or not with cartilage PS showed significant differences. Cartilage PS inhibited the growth of MCF-7 human breast adenocarcinoma cells, but had little effect on normal cells. Cartilage PS can inhibit the activity of the MMP-2 and the MMP-9 by decreasing the levels of LNR1 and alphavbeta3 integrin to inhibit metastasis further. In summary, we conclude that cartilage PS can act as a specific anti-metastatic agent in breast-cancer cells.

Expression of laminin receptor 1 in gestational trophoblastic diseases and normal placenta and its relationship with the development of postmolar tumors

Objectives To investigate the expression of laminin receptor 1 (LR1), a non-integrin-type laminin receptor, in gestational trophoblastic diseases and normal first-trimester placenta, since it may play a role in controlling trophoblast invasion in normal and molar pregnancies. Methods Paraffin sections from 24 gestational age controlled normal first-trimester placentas, 47 partial moles, 56 complete moles, 3 invasive moles, 4 gestational choriocarcinomas, and 1 placental-site trophoblastic tumor were studied immunohistochemically for expression of LR1. Results In complete and partial moles, decidual cells showed significantly stronger LR1 protein staining compared to the normal placenta ( p < 0.01). When compared to the partial moles, weak staining in less than 33% of decidual cells was also more prominent in the normal placenta ( p < 0.05). Complete and partial moles, invasive moles, choriocarcinomas, and placental-site tumors did not differ from each other with respect to staining intensity. Strong immunostaining for LR1 in decidual cells, cytotrophoblasts, syncytiotrophoblasts, and extracellular matrix cells of partial and complete moles was not significantly correlated with the development of persistent postmolar gestational trophoblastic tumors. Conclusions LR1 may be important in the pathogenesis of gestational trophoblastic diseases. The increased expression of LR1 in decidual cells of partial and complete moles may not influence the development of persistent gestational trophoblastic tumor. Since they are seen rarely, multicentric studies should be planned to study LR1 expression in invasive moles and gestational trophoblastic neoplasms.

Overexpression of laminin receptor 1 on decidual cells in partial and complete mole

Objectives. Laminin receptor 1 (LR1), a non-integrin-type laminin receptor, has been described in several tumors and may play a role in tumor invasion. It is well known that LR1 can modify the conformation and degradation of laminin thus enhancing tumor cell invasion. LR1 may play a role in controlling trophoblast invasion in normal and molar pregnancies. Materials and methods. Real-time polymerase chain reaction (RT-PCR) was performed on total cDNA from 17 gestational age-controlled normal placentas, 10 complete moles (CM), and 4 partial moles (PM). Immunolocalization of LR1 was performed on paraffin sections prepared from 17 age-controlled placentas, 17 PM, and 19 CM. Results. RT-PCR demonstrated a 13-fold increase in LR1 mRNA expression in molar tissues (PM and CM combined) versus normal placentas ( p = 0.012). Immunohistochemical analysis revealed LR1 localized to the decidual cells. In normal placenta LR1 localized to the decidual cell membrane. However, in PM and CM, LR1 was additionally noted in the cytoplasm of decidual cells. Interestingly, with immunohistochemistry method, we found that PM demonstrated higher protein expression of LR1 than either normal placenta or CM ( p = 0.001 and p = 0.024, respectively). Conclusion. LR1 is expressed in both the decidual cells of normal placenta and mole (CM and PM). Decidual cells in CM and PM express LR1 significantly greater than the decidual cells in placenta. The underlying mechanism of how molar tissue may be associated with enhanced expression of LR1 in the maternal endometrium is unclear.

Specific killing of multiple myeloma cells by (-)-epigallocatechin-3-gallate extracted from green tea: biologic activity and therapeutic implications

AbstractEpigallocatechin-3-gallate (EGCG), a polyphenol extracted from green tea, is an antioxidant with chemopreventive and chemotherapeutic actions. Based on its ability to modulate growth factor-mediated cell proliferation, we evaluated its efficacy in multiple myeloma (MM). EGCG induced both dose- and time-dependent growth arrest and subsequent apoptotic cell death in MM cell lines including IL-6-dependent cells and primary patient cells, without significant effect on the growth of peripheral blood mononuclear cells (PBMCs) and normal fibroblasts. Treatment with EGCG also led to significant apoptosis in human myeloma cells grown as tumors in SCID mice. EGCG interacts with the 67-kDa laminin receptor 1 (LR1), which is significantly elevated in myeloma cell lines and patient samples relative to normal PBMCs. RNAi-mediated inhibition of LR1 resulted in abrogation of EGCG-induced apoptosis in myeloma cells, indicating that LR1 plays an important role in mediating EGCG activity in MM while sparing PBMCs. Evaluation of changes in gene expression profile indicates that EGCG treatment activates distinct pathways of growth arrest and apoptosis in MM cells by inducing the expression of death-associated protein kinase 2, the initiators and mediators of death receptor-dependent apoptosis (Fas ligand, Fas, and caspase 4), p53-like proteins (p73, p63), positive regulators of apoptosis and NF-κB activation (CARD10, CARD14), and cyclin-dependent kinase inhibitors (p16 and p18). Expression of related genes at the protein level were also confirmed by Western blot analysis. These data demonstrate potent and specific antimyeloma activity of EGCG and provide the rationale for its clinical evaluation.

Distinct gene expression profiles characterize the histopathological stages of disease in Helicobacter-induced mucosa-associated lymphoid tissue lymphoma.

Long-term colonization of humans with Helicobacter pylori can cause the development of gastric B cell mucosa-associated lymphoid tissue lymphoma, yet little is known about the sequence of molecular steps that accompany disease progression. We used microarray analysis and laser microdissection to identify gene expression profiles characteristic and predictive of the various histopathological stages in a mouse model of the disease. The initial step in lymphoma development is marked by infiltration of reactive lymphocytes into the stomach and the launching of a mucosal immune response. Our analysis uncovered molecular markers of both of these processes, including genes coding for the immunoglobulins and the small proline-rich protein Sprr 2A. The subsequent step is characterized histologically by the antigen-driven proliferation and aggregation of B cells and the gradual appearance of lymphoepithelial lesions. In tissues of this stage, we observed increased expression of genes previously associated with malignancy, including the laminin receptor-1 and the multidrug-resistance channel MDR-1. Finally, we found that the transition to destructive lymphoepithelial lesions and malignant lymphoma is marked by an increase in transcription of a single gene encoding calgranulin AMrp-8.