Abstract:How the hosts recognize and clear invading viruses is one of the key issues in molecular immunology. Previous studies uncovered that many early antiviral proteins, such as Type Ⅰ interferons and PKR, are strongly induced upon virus infection. These proteins not only limit virus replication and spread or cause infected cells to undergo apoptosis, but also induce consequently expression of cytokines and chemokines to initiate acquired immunity. However, the immediate-early signaling events among host and virus interaction were largely unknown. In the past few years, there are great breakthroughs in this rapidly evolving field. TLR3 and RIG-I/MDA5 signaling pathways were shown to play a crucial regulatory role in antiviral processes. These pathways are essential for the vertebrate immune system to recognize and clear RNA virus with different strategies, which are integral parts of innate immune response and directly affect later-stage acquired immunity. The recent know-how on TLR3 and RIG-I/MDA5 signal transduction pathways and their roles in antiviral immunity were summarized.

Abstract:Gadd45a, a p53 and BRCA1-regulated growth arrest and DNA damage gene, plays important roles in suppressing cell transformation and tumor malignancy. Gadd45a maintains the genomic stability through inhibiting the cell growth and promoting the DNA repair etc, by which it suppresses the tumor development. Additionally, Gadd45a is involved in some important signaling pathway, contributing to its function in tumor suppressing.

Abstract:Notch signaling pathway plays a vital role in cell fate decisions. Notch signals are transferred among adjacent cells through Notch receptors and their ligands, which can regulate differentiation, proliferation and apoptosis of many cell types including stem cells. They can also influence organ formation and morphopoiesis. Genetic mutations in the Notch signaling pathway are related to the emergence and development of many diseases. Notch signaling pathway is increasingly becoming important drug targets for cancer, hereditary disease such as CADASIL and other related diseases. It is also used to develop stem cell therapeutics to treat age or trauma related degenerative diseases such as Alzheimer's disease, Parkinson disease and diabetes.

Abstract:In order to investigate the effects of β-amyloid (Aβ) deposits on migration of peripheral blood T cells across blood-brain barrier, Aβ_1～42 was stereotaxicly injected into rat hippocampus with reverse peptide Aβ_42～1 as control. After 7 days post-injection, the expression of macrophage inflammatory protein-1α (MIP-1α) and its receptor (CCR5) in peripheral blood T cells was detected by real-time quantitative polymerase chain reaction (RT-qPCR). Brain sections were analyzed with immunofluorescence of CD3, VWF and CCR5. The results showed that Aβ_1～42 deposits in rat brains led to significantly higher expression of MIP-1α in circulating T cells than Aβ_42～1 did, while no increase of CCR5 expression was observed in circulating T cells of Aβ_1～42-injected rats compared to Aβ_42～1-injected rats. Furthermore, the expression of CCR5 was up-regulated by Aβ_1～42 on rat brain microvascular endothelial cells (RBMEC). In addition, T cells were increased in abundance in Aβ_1～42-injected brains compared with Aβ_42～1-injected brains, scattered mainly in cortex and hippocampus. Treatment of Aβ_1～42-injected rats with neutralizing antibody specific for MIP-1α dramatically blocked the enhanced T cells entry into rat brain. The results implied that the interaction between MIP-1α over-expressed in T cells and CCR5 on RBMECs may contribute to the Aβ_1～42-induced circulating T cells migrating across blood-brain barrier.

Abstract:In hippocampus, numerous studies have shown that N-methyl-D-aspartate (NMDA) receptors are essential for the initiation of long-term potentiation (LTP), whereas the expression of LTP is primarily mediated by the phosphorylation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and the increased insertion of postsynaptic AMPA receptors. However, in recent years there is also evidence that NMDA receptor channels contribute to the expression of LTP under physiological conditions. It was examined whether NMDA receptor channels contributed to the expression of LTP of C-fiber evoked field potentials in rat spinal dorsal horn by intravenous or spinal application of NMDA receptor antagonists after the establishment of LTP. It was found that MK 801 (a non-competitive NMDA receptor antagonist) at dose of 0.1 mg/kg (iv) had no effect on the spinal LTP and at the dose of 0.5 mg/kg depressed the LTP significantly. However, the inhibitory effect of MK 801 at higher dose (1.0 mg/kg) was not different from that produced by the dose of 0.5 mg/kg. The similar inhibitory effect on spinal LTP was also observed, when MK 801 was applied locally at the recording segments of spinal cord. To confirm the above results, a competitive NMDA receptor antagonist APⅤ was tested. Spinal application of APⅤ at a concentration of 100 μmol/L produced a stronger depression than at 50 μmol/L. When the concentration of APⅤ increased to 200 μmol/L, no further depression was observed. These results indicate that NMDA receptor channels are involved in the expression of LTP of C-fiber evoked field potentials in the rat spinal dorsal horn.

Abstract:Betacellulin (BTC) is one of “islets regeneration factors” which received more and more attention these years. BTCe is the C-terminal 50-residue region of mature BTC protein and can bind with erbB-1、erbB-4 receptor. It has the same mitogenic activity on cells as the whole section. BTC and BTCe can improve the level of glucose-stimulated insulin secretion (GSIS) during islets culture in vitro though they had no effect on the acute insulin secretion. BTCe also effectively ameliorated the hyperglycemia of STZ-induced diabetic rats by a single plasmid injection into muscle of rats. It is supposed that BTCe promote the proliferation of PDX-1 positive cells or repair some signal transduction pathway. Perhaps the latter is more important.

Abstract:Numerous peptides that bind to a given target have been selected by phage display technology. However, some peptides isolated to date do not bind with high affinity to tumor or organ sites, even peptides were selected in vivo. Therefore, the biodistribution of ^99mTc-labeled filamentous phage peptide library via MAG3 (mercaptoacetyltriglycine) were investigated to gain a better understanding of phage circulation in vivo. The experimental results showed that the liver and spleen were the organs of the greatest accumulation, while heart, muscle, pancreas and brain retained less radioactivity. In opposite to other tissues and organs, the radioactivity in stomach, intestine and bone gradually went up with time. The clearance of ^99mTc-labeled phage in blood was very fast from 5 min to 30 min and then slowed down. When phage in vivo circulated at enough long period of time, some phage particles could extravasate in some organs or tissues and internalized there. In conclusion, the circulation time of phage in vivo should be experimentally determined beforehand according to the targeted organs and the specific location of target peptides in order to panning a peptide with high specificity and affinity to that target.

Abstract:The metagenomic DNA was extracted from the deep sea sediment with the depth of 900m of Prydz Bay, Antarctic. A lipase gene (lip3) with the size of 948bp was cloned from the metagenomic DNA by PCR with the primers designed. The deduced Lip3 protein was composed of 315 amino acids (AA) with a molecular mass of 34.577 ku. The motifs GFGNS(GXGXS)and G-N-S-M-G(GXSXG)in the AA sequences of Lip3 were found to be conserved in other lipase. They were most conserved sequence among the serine hydrolase and were necessary for the activity. A 35 ku of Lip3 was purified by Ni-NTA chelating sepharose column from the extract of recombinant E.coli Top 10F′ cell harboring a pLLP-OmpA plasmid inserted with lip3. The purified Lip3 was most active at 25℃ and kept 22% of activity at 0℃. Only 10% of activity was retained after it was incubated at 35℃ for 60 min. The optimal pH value for the Lip3 activity was 8.0. The K_m value of the enzyme towards p-nitrophenyl palmitate increased with the increasing of assayed temperature. These results indicated that Lip3 was a typical alkaline cold active enzyme.

Abstract:Alignment-free comparison is a recently developed method for sequence alignment, which has high computational efficiency and suitable to the low identical sequences. Alignment-free comparison was successfully applied in the DNA analysis. However, the accuracy of analysis is not high when it was applied in protein analysis because the complexity of protein is larger than DNA by consisting of 20 types of residues. Thus, residues are clustered into a few groups based on their similarity of physicochemical features. Using such simplified alphabets, the complexity of protein sequences is reduced and at the same time the key information encoded in the sequences remains. Therefore, the accuracy of alignment-free comparison is improved.

Abstract:Glutathione S-transferase (GST) gene, PcgstA was cloned from the penicillin producing strain Penicillium chrysogenum, which is important for understanding the industrial fermentation process. PcgstA gene has an open-reading-frame of 840 bp in length, which is interrupted by two introns. The deduced amino acid sequence shows about 50% identity to several characterized filamentous fungi GSTs. The recombinant PcGSTA in Escherichia coli were overexpressed and purified. Enzymatic assays showed that the recombinant PcGSTA had a specific activity with 1-chloro-2, 4-dinitrobenzene of (0.159±0.031) μmol/(min·mg). It was found that the expression level of PcgstA in the penicillin producing medium supplemented with phenylacetic acid, the side chain precursor of penicillin G, was significant down regulated than that in medium without phenylacetic acid. This result suggested that PcGST may be related to phenylacetic acid metabolism in the penicillin producing strain.