Induction of integrin β3 in PGE2-stimulated adhesion of mastocytoma P-815 cells to the Arg-Gly-Asp-enriched fragment of fibronectin

An integrin alpha 4 (ChIntα 4) from oyster Crassostrea hongkongensis mediates the hemocytes phagocytosis towards Vibrio alginolyticus

Integrins, a family of cell adhesion transmembrane receptors, mediate cell adhesion, migration, proliferation, apoptosis, and phagocytosis. In the present study, an integrin ChIntα 4 from Crassostrea hongkongensis was characterized to investigate its role in defensing against pathogenic bacterium Vibrio alginolyticus. The full-length cDNA sequence of ChIntα 4 was 3572 bp with an open reading frame (ORF) of 3168 bp, which encoded a polypeptide with 1055 amino acids. The mRNA expression of ChIntα 4 in the hemocytes was significantly up-regulated at 6 h and 24 h post V. alginolyticus stimulation (p < 0.01). The recombinant ChIntα 4 protein could agglutinate the rabbit red blood cells and Gram-negative bacteria V. alginolyticus and Escherichia coli. Moreover, the phagocytic activity of the hemocytes was significantly down-regulated from 46.9% to 32.7% when blocked with anti-ChIntα 4 antibody, and it was significantly up-regulated from 42.7% to 59.5% post transfection with pCI-neo-ChIntα 4 plasmid (p < 0.05). In conclusion, these findings demonstrated that ChIntα 4 might be involved in resisting V. alginolyticus infection and regulating phagocytosis as a cell adhesion receptor in C. hongkongensis.

Endothelin-1 induces cellular senescence and fibrosis in cultured myoblasts. A potential mechanism of aging-related sarcopenia

Endothelial dysfunction, with increased endothelin-1 (ET-1) synthesis, and sarcopenia, characterized by the loss of muscular mass and strength, are two aging–related conditions. However, a relationship between them has not been already established. The aim of this study was to determine whether ET-1 induces senescence and fibrosis in cultured murine myoblasts, which could be involved in the development of sarcopenia related to aging. For this purpose, myoblasts were incubated with ET-1 to assess cellular senescence, analyzed by senescence associated β-galactosidase activity and p16 expression; and fibrosis, assessed by fibronectin expression. ET-1 induced myoblast senescence and fibrosis through ET_A receptor. The use of antioxidants and several antagonists revealed that ET-1 effect on senescence and fibrosis depended on ROS production and activation of PI₃K-AKT-GSK pathway. To stress the in vivo relevance of these results, circulating ET-1, muscular strength, muscular fibrosis and p16 expression were measured in male C57Bl6 mice from 5-18-24-months-old. Old mice shown high levels of ET-1 correlated with muscular fibrosis, muscular p16 expression and loss of muscle strength. In conclusion, ET-1 promotes fibrosis and senescence in cultured myoblasts, similar results were found in old mice, suggesting a potential role for ET-1 in the development of sarcopenia related to aging.

A novel integrin function in innate immunity from Chinese mitten crab (Eriocheir sinensis)

Integrins belong to a superfamily of conserved α β heterodimeric cell surface receptors that have critical function in cell migration, differentiation, and survival. In this study, an integrin called EsIntegrin was identified from Chinese mitten crab Eriocheir sinensis. EsIntegrin cDNA is 4415 bp long with a 2457 bp open reading frame that encodes an 818 amino acid protein. EsIntegrin contains a signal peptide, an integrin beta subunit (N-terminal portion of extracellular region) INB domain, an epidermal growth factor (hEGF) domain, an integrin B tail domain, a transmembrane region, and an integrin b cyt domain. EsIntegrin was mainly expressed in hemocytes and the heart, with a relatively lower expression level in gills, nerves, intestine, hepatopancreas, muscles, and eyestalk. When healthy crabs were challenged with LPS, PGN, Staphyloccocus aureus, or Vibrio parahaemolyticus, EsIntegrin expression level was upregulated significantly. Recombinant EsIntegrin has agglutination activity to Gram-positive (e.g., S. aureus and Bacillus subtilis) and Gram-negative bacteria (e.g., V. parahaemolyticus and Aeromonas hydrophila) in the presence of calcium. Furthermore, rEsIntegrin could not only bind to various bacteria such as S. aureus, Micrococcus luteus, B. subtilis, Bacillus megaterium, Bacillus thuringiensis, V. parahaemolyticus, Vibrio anguillarum, A. hydrophila, Vibrio natriegens, and Escherichia coli, but this compound also helped crabs in clearing virulent Gram-negative bacterium, V. parahaemolyticus, in vivo. These data suggested that EsIntegrin might function as cellular receptor that is involved in anti-bacterial immunity from E. sinensis.

Role of lipid raft components and actin cytoskeleton in fibronectin-binding, surface expression, and de novo synthesis of integrin subunits in PGE2- or 8-Br-cAMP-stimulated mastocytoma P-815 cells

Integrins are heterodimeric adhesion receptors essential for adhesion of non-adherent cells to extracellular ligands such as extracellular matrix components. The affinity of integrins for ligands is regulated through a process termed integrin activation and de novo synthesis. Integrin activation is regulated by lipid raft components and the actin structure. However, there is little information on the relationship between integrin activation and its de novo synthesis. Cancerous mouse mast cells, mastocytoma P-815 cells (P-815 cells) are known to bind to fibronectin through de novo synthesis of integrin subtypes by prostaglandin (PG) E2 stimulation. The purpose of this study was to clarify the relationship between lipid raft components and the actin cytoskeleton, and PGE2-induced P-815 cells adhesion to fibronectin and the increase in surface expression and mRNA and protein levels of αvβ3 and αIIbβ3 integrins. Cholesterol inhibitor 6-O-α-maltosyl-β cyclodextrin, glycosylphosphatidylinositol-anchored proteins inhibitor phosphatidylinositol-specific phospholipase C and actin inhibitor cytochalasin D inhibited PGE2-induced cell adhesion to fibronectin, but did not regulate the surface expression and mRNA and protein levels of αv and αIIb, and β3 integrin subunits. In addition, inhibitor of integrin modulate protein CD47 had no effect on PGE2- and 8-Br-cAMP-induced cell adhesion. These results suggest that lipid raft components and the actin cytoskeleton are directly involved in increasing of adhesion activity of integrin αIIb, αv and β3 subunits to fibronectin but not in stimulating of de novo synthesis of them in PGE2-stimulated P-815 cells. The modulation of lipid rafts and the actin structure is essential for P-815 cells adhesion to fibronectin.

An integrin from shrimp Litopenaeus vannamei mediated microbial agglutination and cell proliferation

BACKGROUND

Integrins are a family of adhesion receptors which regulate cell proliferation, differentiation, leukocyte migration, and complement receptor-dependent phagocytosis. In invertebrates, as a cell adhesion receptor, β integrins play an important role for the balanced activation of immune defense responses especially during the encounter of infections. The present study attempts to characterize the immune functions of shrimp integrin (LvIntegrin) to have better understanding on the immune system and its regulation mechanisms in shrimps.

METHODOLOGY

A shrimp integrin was identified from the Pacific white shrimp Litopenaeus vannamei (designated as LvIntegrin). Its full-length cDNA was of 2621 bp with an open reading frame (ORF) of 2439 bp encoding a polypeptide of 812 amino acids. The mRNA expression of LvIntegrin was significantly up-regulated at 3, 6 and 12 h after Listonella anguillarum challenge. The cDNA fragment encoding β integrin domains (βA and hybrid domain) of LvIntegrin was recombined and expressed in Escherichia coli BL21(DE3)-pLysS. The recombinant protein (rLvIntegrin) could significantly agglutinate the tested microbe including E. coli JM109, L. anguillarum, Micrococcus luteus and Candida dattiladattila in the presence of divalent cations. Moreover, when NIH3T3 cells were cultured with rLvIntegrin, the proliferation rate increased significantly in a dose-dependent manner.

CONCLUSIONS

LvIntegrin, a shrimp β integrin was identified from L. vannamei, shared several highly conserved features. LvIntegrin exhibited broad-spectrum agglutination activity towards both bacteria and fungi and could improve the proliferation of NIH3T3 cells, indicating that LvIntegrin is involved in the immune response against microbe challenge and regulation of cell proliferation as a cell adhesion receptor in shrimp.

Biogenic monoamines in preimplantation development

BACKGROUND

The involvement of biogenic monoamines in early ('preneural') embryogenesis has been well documented in lower vertebrates, but much less information is available about the role of these molecules in the earliest stages of development in mammals, including humans.

METHODS

Databases (PubMed, ISI Web of Knowledge and Scopus) were searched for studies relating to biogenic monoamines functioning in early embryos. The available data on the expression of histamine, serotonin and adrenergic receptors during mammalian preimplantation development were summarized, and the potential roles of biogenic monoamines in very early pregnancy were discussed.

RESULTS

The roles of biogenic monoamines in mammalian preimplantation embryo development can be diverse, depending on the embryo developmental stage, and the physiological status of the maternal organism. Several receptors for biogenic monoamines are expressed and biologically functional in cells of preimplantation embryos. Activation of histamine receptors can play a role in embryo implantation and trophoblast invasion. Activation of adrenergic and serotonin receptors can influence proliferation and survival of early embryonic cells.

CONCLUSIONS

Biogenic monoamines can play an important role in physiological conditions, contributing to embryo-maternal interactions, or can influence the early embryo under unfavorable or pathological conditions (e.g. in maternal stress, or in women taking certain antidepressants, anti-migraine or anti-ulcer drugs).