Expression of Heat Shock Proteins in Thermally Challenged Pacific Abalone Haliotis discus hannai.

Summer mortality, caused by thermal conditions, is the biggest threat to abalone aquaculture production industries. Various measures have been taken to mitigate this issue by adjusting the environment; however, the cellular processes of Pacific abalone (Haliotis discus hannai) have been overlooked due to the paucity of genetic information. The draft genome of H. discus hannai has recently been reported, prompting exploration of the genes responsible for thermal regulation in Pacific abalone. In this study, 413 proteins were systematically annotated as members of the heat shock protein (HSP) super families, and among them 26 HSP genes from four Pacific abalone tissues (hemocytes, gill, mantle, and muscle) were differentially expressed under cold and heat stress conditions. The co-expression network revealed that HSP expression patterns were tissue-specific and similar to those of other shellfish inhabiting intertidal zones. Finally, representative HSPs were selected at random and their expression patterns were identified by RNA sequencing and validated by qRT-PCR to assess expression significance. The HSPs expressed in hemocytes were highly similar in both analyses, suggesting that hemocytes could be more reliable samples for validating thermal condition markers compared to other tissues.

Observation of Restored Topological Surface States in Magnetically Doped Topological Insulator.

The introduction of ferromagnetic order in topological insulators in general breaks the time-reversal symmetry and a gap is opened in topological surface bands. Various studies have focused on gap-opened magnetic topological insulators, because such modified band structures provide a promising platform for observing exotic quantum physics. However, the role of antiferromagnetic order in topological insulators is still controversial. In this report, we demonstrate that it is possible to restore the topological surface states by effectively reducing the antiferromagnetic ordering in Gd-substituted Bi2Te3. We successfully control the magnetic impurities via thermal treatments in ultra-high vacuum condition and observe apparent restoration of topological surface band dispersions. The microscopic mechanism of atomic rearrangements and the restoration process of topological surface states are unraveled by the combination of scanning tunneling microscopy measurements and density functional theory calculations. This work provides an effective way to control the magnetic impurities which is strongly correlated with topological surface states.

Development of novel antimicrobial peptides derived from anti-lipopolysaccharide factor of the swimming crab, Portunus trituberculatus.

Anti-lipopolysaccharide factors (ALFs) are a representative host defense protein in crustaceans. In this study, we successfully developed two novel antimicrobial peptides (AMPs), named crab-ALF2A and crab-ALF6A, which contain changes to the amino acid sequences of the lipopolysaccharide binding domain and signal peptide, respectively, of the ALF of the swimming crab Portunus trituberculatus. The crab-ALF2A peptide showed potent antimicrobial activity against the Gram-positive bacteria Bacillus cereus, Staphylococcus aureus, and Streptococcus iniae (minimal effective concentration [MEC] 1.51-1.93 µg/mL) and the Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli (MEC 1.87-1.98 µg/mL), with maximal bactericidal activity at a peptide concentration of 5 µg/mL. The crab-ALF6A peptide also showed potent antimicrobial activity against B. cereus, S. aureus, and S. iniae (MEC 1.49-2.3 µg/mL) and P. aeruginosa and E. coli (MEC 1.72-1.19 µg/mL) at a peptide concentration of 5 µg/mL. Notably, the crab-ALF2A and crab-ALF6A peptides exhibited strong activity against Candida albicans (MECs of 2.11 and 1.95 µg/mL, respectively). These activities were stable following heat treatment. Moreover, the effect of crab-ALF2A and crab-ALF6A peptide treatment on microbe cell morphology was confirmed by scanning electron microscopy. Membrane disruption and damage, and the leakage of cytoplasmic content were clearly observed. A downsizing peptide approach illustrated that the hexapeptide ALF6A8 (RVLLRL) was the shortest peptide showing significant antimicrobial activity. Our approach allows for the generation of novel antimicrobial peptides in a cost effective manner as potential next-generation antibiotics.

Expression of Msgn1 in the presomitic mesoderm is controlled by synergism of WNT signalling and Tbx6.

The vertebral column and skeletal muscles of vertebrates are derived from the paraxial mesoderm, which is laid down initially as two stripes of mesenchymal cells alongside the neural tube and subsequently segmented. Previous work has shown that the wingless-type MMTV integration site family (WNT), fibroblast growth factor- and Delta-Notch signalling pathways control presomitic mesoderm (psm) formation and segmentation. Here, we show that the expression of mesogenin 1, a basic helix-loop-helix transcription factor, which is essential for psm maturation, is regulated by synergism between WNT signalling and the T-box 6 transcription factor, involving a feed-forward control mechanism. These findings emphasize the crucial role of WNT signalling in the control of psm formation, maturation and segmentation.

F2L, a peptide derived from heme-binding protein, inhibits formyl peptide receptor-mediated signaling.

F2L is an acetylated amino-terminal peptide derived from the cleavage of the human heme-binding protein. Very recently, F2L was identified as an endogenous chemoattractant peptide acting specifically through formyl peptide receptor-like (FPRL)2. In the present study, we report that F2L stimulates chemotactic migration in human neutrophils. However, F2L inhibits formyl peptide receptor (FPR) and FPRL1 activities, resulting in the complete inhibition of intracellular calcium increases, and superoxide generation induced by N-formyl-Met-Leu-Phe, MMK-1, or Trp-Lys-Tyr-Met-Val-d-Met (WKYMVm) in human neutrophils. In terms of the inhibitory role of F2L on FPR- and FPRL-mediated signaling, we found that F2L competitively inhibits the binding of (125)I-WKYMVm to its specific receptors, FPR and FPRL1. F2L is the first endogenous molecule that inhibits FPR- and FPRL1-mediated signaling, and is expected to be useful in the study of FPR and FPRL1 signaling and in the development of drugs to treat diseases involving the FPR family of receptors.

Sphingosylphosphorylcholine stimulates human monocyte-derived dendritic cell chemotaxis.

AIM: To investigate the effects of sphingosylphosphorylcholine (SPC) on human monocyte-derived dendritic cell (DC) chemotaxis. METHODS: Human DC were generated from peripheral blood monocytes by culturing them with granulocyte macrophage-colony stimulating factor and interleukin-4. The effect of SPC on the DC chemotactic migration was measured by chemotaxis assay. Intracellular signaling event involved in the SPC-induced DC chemotaxis was investigated with several inhibitors for specific kinase. The expression of the SPC receptors was examined by reverse transcription polymerase chain reaction. RESULTS: We found that SPC induced chemotactic migration in immature DC (iDC) and mature DC (mDC). In terms of SPC-induced signaling events, mitogen activated protein kinase activation and Akt activation in iDC and mDC were stimulated. SPC-induced chemotaxis was mediated by extracellular signal-regulated protein kinase and phosphoino-sitide-3-kinase, but not by calcium in both iDC and mDC. Although mDC express ovarian cancer G protein-coupled receptor 1, but not G protein-coupled receptor 4, iDC do not express any of these receptors. To examine the involvement of sphingosine-1-phosphate (S1P) receptors, we checked the effect of an S1P receptor antagonist (VPC23019) on SPC-induced DC chemotaxis. VPC23019 did not affect SPC-induced DC chemotaxis. CONCLUSION: The results suggest that SPC may play a role in regulating DC trafficking during phagocytosis and the T cell-stimulating phase, and the unique SPC receptor, which is different from S1P receptors, is involved in SPC-induced chemotaxis.

Leukotriene B4 stimulates human monocyte-derived dendritic cell chemotaxis.

Although leukotriene B4 (LTB4) has been reported to stimulate monocytes and neutrophils, its role on dendritic cell (DC) activity has not been examined. Here, we investigated the expression of LTB4 receptor and the effect of LTB4 on human DC chemotaxis. We analyzed LTB4 receptors, BLT1 and BLT2, by using RT-PCR. DCs express BLT2 but not BLT1 mRNA. DCs were chemotactically migrated to LTB4. LTB4-induced DC chemotaxis was completely inhibited by pertussis toxin, indicating the role of Gi proteins. LTB4 induced mitogen activated protein kinase activation and Akt activation. LTB4-induced DC chemotaxis was mediated by extracellular signal-regulated protein kinase and phosphoinositide 3-kinase but not by p38 kinase. BLT2-selevite antagonist, LY255283, almost completely inhibited DC chemotaxis induced by LTB4 but not by Trp-Lys-Tyr-Met-Val-D-Met. Thus human myeloid DCs express functional BLT2 but not BLT1, suggesting a physiological role of LTB4 and BLT2 in regulating DC trafficking during induction of immune responses.

Serum amyloid A induces contrary immune responses via formyl peptide receptor-like 1 in human monocytes.

Although the level of serum amyloid A has been reported to be up-regulated during inflammatory response, the role of serum amyloid A on the regulation of inflammation and immune response has not been elucidated. We found that serum amyloid A stimulated the production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10, which are proinflammatory and anti-inflammatory cytokines, respectively, in human monocytes. Low concentrations of serum amyloid A stimulated TNF-alpha production with maximal activity at 6 h after stimulation, whereas high concentrations of serum amyloid A stimulated IL-10 production with maximal activity at 12 h. The activations of the two cytokines by serum amyloid A occurred at both the transcription and translational levels. Signaling events induced by serum amyloid A included the activation of two mitogen-activated protein kinases (extracellular signal-regulated kinase and p38 kinase), which were found to be required for TNF-alpha and IL-10 production, respectively. The stimulation of formyl peptide receptor-like-1-expressing RBL-2H3 cells, but not of vector-expressing RBL-2H3 cells with serum amyloid A, induced mitogen-activated protein kinases activation and the accumulation of the RNAs of these two cytokines. Together, our findings suggest that serum amyloid A modulates contrary immune responses via formyl peptide receptor-like 1, by inducing TNF-alpha or IL-10, and demonstrate that extracellular signal-regulated kinase and p38 kinase play counteracting roles in this process.

Trp-Arg-Trp-Trp-Trp-Trp antagonizes formyl peptide receptor like 2-mediated signaling.

Although formyl peptide receptor like 2 (FPRL2) has been regarded as an important classical chemoattractant receptor, its functional role and signaling pathway have not been fully investigated, because of the lack of its specific ligand. Recently F2L, a heme-binding protein fragment peptide, has been reported as an FPRL2-selective endogenous agonist. In the present study, we examined the effect of Trp-Arg-Trp-Trp-Trp-Trp-CONH2 (WRWWWW, WRW4), on F2L-induced cell signaling. WRW4 inhibited the activation of FPRL2 by F2L, resulting in the complete inhibition of intracellular calcium increase and chemotactic migration induced by F2L. WRW4 also completely inhibited F2L-induced NF-kappaB activation in FPRL2-transfected HEK293 cells. WRW4 specifically inhibited F2L-induced intracellular calcium increase and chemotactic migration in mature monocyte-derived dendritic cells, which express FPRL2 but not the other FPR family. Taken together, WRW4 is the first FPRL2 antagonist and is expected to be useful in the study of FPRL2 signaling and in development of drugs against FPRL2-related cellular responses.

Lysophosphatidylserine stimulates L2071 mouse fibroblast chemotactic migration via a process involving pertussis toxin-sensitive trimeric G-proteins.

Lysophosphatidylserine (LPS) may be generated after phosphatidylserine-specific phospholipase A2 activation. However, the effects of LPS on cellular activities and the identities of its target molecules have not been fully elucidated. In this study, we observed that LPS stimulates an intracellular calcium increase in L2071 mouse fibroblast cells, and that this increase was inhibited by 1-[6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]-1H-pyrrole-2,5-dione (U-73122) but not by pertussis toxin, suggesting that LPS stimulates calcium signaling via G-protein coupled receptor-mediated phospholipase C activation. Moreover, LPS-induced calcium mobilization was not inhibited by the lysophosphatidic acid receptor antagonist, (S)-phosphoric acid mono-{2-octadec-9-enoylamino-3-[4-(pyridine-2-ylmethoxy)-phenyl]-propyl} ester (VPC 32183), thus indicating that LPS binds to a receptor other than lysophosphatidic acid receptors. It was also found that LPS stimulates two types of mitogen-activated protein kinase [i.e., extracellular signal-regulated protein kinase (ERK) and p38 kinase] in L2071 cells. Furthermore, these LPS-induced ERK and p38 kinase activations were inhibited by pertussis toxin, which suggests the role of pertussis toxin-sensitive G-proteins in the process. In terms of functional issues, LPS stimulated L2071 cell chemotactic migration, which was completely inhibited by pertussis toxin, indicating the involvement of pertussis toxin-sensitive G(i) protein(s). This chemotaxis of L2071 cells induced by LPS was also dramatically inhibited by 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) and by 2'-amino-3'-methoxyflavone (PD98059). This study demonstrates that LPS stimulates at least two different signaling cascades, one of which involves a pertussis toxin-insensitive but phospholipase C-dependent intracellular calcium increase, and the other involves a pertussis toxin-sensitive chemotactic migration mediated by phosphoinositide 3-kinase and ERK.

Regulation of phosphorylation of NMDA receptor NR1 subunits in the rat neostriatum by group I metabotropic glutamate receptors in vivo.

Group I metabotropic glutamate receptors (mGluRs) are Galphaq-protein-coupled receptors and are densely expressed in medium-sized spiny projection neurons of the neostriatum. Among different subtypes of glutamate receptors, group I mGluRs have been demonstrated to actively interact with the ionotropic glutamate receptor N-methyl-d-aspartate (NMDA) subtypes for regulating various forms of cellular activities and synaptic plasticity. In this study, the possible role of group I mGluRs in regulating serine phosphorylation of NMDA receptor NR1 subunits in the neostriatum was investigated in vivo. We found in chronically cannulated rats that injection of the group I mGluR agonist 3,5-dihydroxyphenylglycine (DHPG) into the dorsal striatum (caudate putamen) significantly increased phosphorylation of the two serine residues (serine 896 and serine 897) on the intracellular C-terminus of the NR1. The increase in NR1 phosphorylation was dose-dependent and DHPG had no effect on basal levels of NR1 proteins. Intrastriatal infusion of the group I mGluR antagonist N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC) significantly attenuated the DHPG-stimulated NR1 phosphorylation. Pretreatment with the mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) also produced the same effect. These data suggest that group I mGluRs, likely mGluR5 subtypes, possess the ability to upregulate protein phosphorylation of NMDA receptor NR1 subunits in striatal neurons in vivo.

Lysophosphatidic acid stimulates cell proliferation in rat chondrocytes.

Rat primary chondrocytes express the lysophosphatidic acid (LPA) receptor, LPA1, LPA3, but not LPA2. When chondrocytes were stimulated with LPA, phospholipase C-mediated cytosolic calcium increase was dramatically induced. LPA also stimulated two kinds of mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK) and p38 kinase in chondrocytes. In terms of the LPA-mediated functional modulation of chondrocytes, LPA stimulated cellular proliferation. We examined the signaling pathways involved in LPA-mediated cellular proliferation. LPA-induced chondrocyte proliferation was almost completely blocked by 2'-amino-3'-methoxyflavone (PD98059) but not by 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580), suggesting that ERK activity is essentially required for the process. Pertussis toxin almost completely inhibited the LPA-induced cellular proliferation and ERK activation, indicating the role of G(i/o) protein(s) in the processes. This study demonstrates the physiological role of LPA on the modulation of rat primary chondrocyte proliferation, and the crucial role played by ERK in the process.

Group IB secretory phospholipase A2 stimulates leukotriene B4 production by a unique mechanism in human neutrophils.

We found that group IB secretory phospholipase A(2) (sPLA(2)-IB) stimulates leukotriene B4 (LTB4) production in the absence of cytochalasin B in human neutrophils. Although LTB4 production has been reported to be associated with arachidonic acid release, the exogenous addition of sPLA(2)-IB did not induce this release from human neutrophils, suggesting that sPLA(2)-IB stimulates LTB4 production without affecting arachidonic acid. Moreover, the intracellular signaling events induced by sPLA(2)-IB included an increase in intracellular Ca(2+), which is required for LTB4 production. sPLA(2)-IB also stimulated mitogen-activated protein kinase ERK, but its activity was not required for LTB4 production. In terms of functional aspects, the supernatant of sPLA(2)-IB-stimulated human neutrophils caused chemotactic migration, which was almost completely inhibited by preincubating these cells with three different 5-lipoxygenase inhibitors (MK-886, AA-861, or NDGA). Taken together, we suggest that sPLA(2)-IB plays a role in the modulation of inflammatory and immune responses by inducing LTB4 production in human neutrophils.

Lysophosphatidylserine stimulates leukemic cells but not normal leukocytes.

In this study, we observed that lysophosphatidylserine (LPS) stimulated intracellular calcium ([Ca(2+)](i)) increase in leukemic cells but not in normal human peripheral blood mononuclear cells. LPS also stimulated [Ca(2+)](i) increase in human leukemic THP-1 cells. LPS-stimulated [Ca(2+)](i) increase was inhibited by U-73122 but not by U-73343. LPS also stimulated inositol phosphates formation in THP-1 cells, suggesting that LPS stimulates calcium signaling via phospholipase C activation. Moreover, pertussis toxin (PTX) completely inhibited [Ca(2+)](i) increase by LPS, indicating the activation of PTX-sensitive G-proteins. We also found that LPS-induced [Ca(2+)](i) increase was completely inhibited by suramin, suggesting G-protein coupled receptor activation. Since LPS specifically stimulates PTX-sensitive G-proteins, phospholipase C-dependent [Ca(2+)](i) increase in leukemic cells but not normal peripheral blood leukocytes, LPS receptor may be associated with leukemia.

Inhibition of protein phosphatase 2B upregulates serine phosphorylation of N-methyl-D-aspartate receptor NR1 subunits in striatal neurons in vivo.

This study investigated the role of protein phosphatase 2B (calcineurin) in regulating phosphorylation of N-methyl-D-aspartate receptor (NMDAR) NR1 subunits and other phosphoproteins in the rat striatum in vivo. In chronically cannulated rats, microinjection of the calcineurin selective inhibitor cyclosporin A increased phosphorylation of NMDAR NR1 subunits at serine 896 and serine 897 in the injected dorsal striatum. The increase in NMDAR NR1 phosphorylation was dose-dependent in a dose range surveyed (0.005, 0.05, and 0.5 nmol). Parallel with increased serine phosphorylation of NR1 subunits, cyclosporin A dose-dependently increased phosphorylation of a Ca2+-sensitive protein kinase, extracellular signal-regulated protein kinase 1/2 (ERK1/2), and a Ca2+/cAMP-sensitive transcription factor, cAMP response element-binding protein (CREB), in the dorsal striatum. Using an immediate early gene product Fos as a reporter of inducible gene expression, cyclosporin A was found to upregulate Fos expression in the dorsal striatum. These results indicate that calcineurin plays an important role in the tonic dephosphorylation of NMDAR NR1 subunits and other two key cytoplasmic and nuclear signaling proteins (ERK1/2 and CREB) in striatal neurons.