ABSTRACT
Autophagy is a lysosomal-dependent catabolic pathway that is widely present in eukaryote andinvolved in multiple biological functions, such as cytodifferentiation, starvation tolerance and immunedefense. Specially, the autophagy process that recognizes and eliminates intracellular pathogens is definedas xenophagy, which is a vital way for immune cells to execute host defense. However, pathogens haveevolved several strategies to cope with xenophagy via distinct types of virulence factors (effectors, surfaceproteins, etc.). Studies have shown that the autophagy regulatory signals are sophisticated, which areprecisely directed by a variety of autophagy related proteins (ATG proteins). It has been proved that thekey steps of autophagy undergo extensive protein post-translational modifications (PTMs), such asphosphorylation/ dephosphorylation, and ubiquitination/ deubiquitination, etc. These modifications endowthe autophagy regulation with a high degree of dynamics and reversibility via affecting the structure, stability, activity and location of the proteins. Recently, some virulence factors were found to hijackPTMs of the ATG proteins and then affect host autophagy related pathways, thereby resisting xenophagyand promoting pathogens’ survival in the host cell. This review summarizes the current knowledge ofPTMs in xenophagy, especially the mechanisms that pathogens manipulate host xenophagy through PTMs, providing a guidance for exploring xenophagy intervention strategies and controlling infectious diseases.
ABSTRACT
BACKGROUND: Bone morphogenetic protein 2 (BMP-2) has a strong ability to induce and promote the osteogenic differentiation of mesenchymal stem cells. OBJECTIVE: To evaluate the BMP-2 effect on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) on an injectable nano-hydroxyapatite/chitosan (nHA/CS) composite scaffold. METHODS: (1) Experiment 1: Passage 3 BMSCs were divided into two groups and cultured with the nHA/CS scaffold or cultured alone. Cell counting kit-8 was used to detect cell proliferation at 1, 3, 5, 7, 14 days of culture. (2) Experiment 2: Passage 3 BMSCs were seeded onto the nHA/CS scaffold and cultured in culture medium containing BMP-2 or not. Alkaline phosphatase activity in cells was detected at 3, 6, 9, 12, 15 days of culture. Cell counting kit-8 was used to detect cell proliferation at 1, 3, 5, 7, 14 days of culture. Alizarin red staining was used to observe the osteogenic differentiation of cells at 1 and 2 weeks of culture. RESULTS AND CONCLUSION: (1) Experiment 1: With the prolongation of culture time, the absorbance values in the two groups were gradually increased, but there was no significant difference between the two groups. At 7 days of culture, the BMSCs adhered tightly to the scaffold surface. (2) Experiment 2: With the prolongation of culture time, the alkaline phosphatase activities in the two groups were gradually increased, and moreover, the alkaline phosphatase activity in the experimental group was higher than that in the control group at different culture time (P < 0.05). The absorbance values in the two groups were also gradually increased, and the value in the experimental group was higher than that in the control group at different culture time (P < 0.05). At 1 and 2 weeks of culture, the number of calcified nodules was higher in the experimental group than the control group. To conclude, BMP-2 has a promotion role in the proliferation and differentiation of BMSCs cultured on the injectable nHA/CS scaffold.
ABSTRACT
Radix Adenophorae, a traditional Chinese medicine, has been reported to have a variety of biological functions. In the present study, a polysaccharide component, Radix Adenophorae Polysaccharide (RAPS), was purified from Radix Adenophorae by decoloring with ADS-7 macroporous adsorption resin, DEAE-52 cellulose ion-exchange chromatography, and Sephacryl S-300HR gel chromatography, with the purity of 98.3% and a molecular weight of 1.8 × 10(4) Da. The cell viability assay and microscopic examination revealed that RAPS promoted the proliferation and activation of macrophages. At 400 μg·mL(-1), RAPS stimulated RAW264.7 cell proliferation by 1.91-fold compared with the control. Meanwhile, RAPS significantly increased the secretion of pro-inflammatory cytokines (TNF-α and IL-6) in a dose-dependent manner in the supernatant of RAW264.7 cell culture as determined by ELISA. At 400 μg·mL(-1), the production of TNF-iα was 20.8-fold higher than that of the control. Simultaneously, the production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) were increased in RAW264.7 cells incubated with RAPS, as measured by Griess assay and Western blot analysis. The NO production of cells treated with RAPS (400 μg·mL(-1)) reached 15.8 μmol·L(-1), which was 30.4-fold higher than that of the control (0.53 μmol·L(-1)). These data suggested that RAPS may enhance the immune function and protect against exogenous pathogens by activating macrophages.
Subject(s)
Animals , Mice , Campanulaceae , Chemistry , Cytokines , Genetics , Allergy and Immunology , Immunologic Factors , Pharmacology , Interleukin-6 , Genetics , Allergy and Immunology , Macrophage Activation , Macrophages , Allergy and Immunology , Nitric Oxide , Allergy and Immunology , Plant Extracts , Pharmacology , Polysaccharides , Pharmacology , Tumor Necrosis Factor-alpha , Genetics , Allergy and ImmunologyABSTRACT
The nitrite-reducing activity of aerobic denitrifying bacterial strain N6-1 was studied. It showed that the nitrite-reducing activity reached the highest at 30℃, 120 r/min, pH 8.5 and C/N ratio 12, using CH3COONa and NaNO2 as the sole carbon source and nitrogen source, respectively. When the initial NaNO2 concentration was 2 g/L, NO2--N was reduced completely after 20 hours cultivation with the reducing rate of 20.3 mg/L?h. There would be no effect on its nitrite-reducing activity in the present of 1.5% NaCl or 1% peptone. The cell concentration could reach 1.2?1011 CFU/mL after 24 hours cultivation in 10 L fermentor.
ABSTRACT
As to a nitrite-oxidizing bacterium screened in our laborator y, the effect of pH, nitrogen sources, carbon sources and sodium chloride on its g rowth was studied in order to obtain high cell density. It showed that the cult ure conditions of nitrite- oxidizing bacterium were 4500mg/L sodium nitrite, 1 .5g/L sodium carbonate, 0~0.5% sodium chloride and 0~0.1% glucose at 28℃~30 ℃, 110 r/min and pH 8.0~8.5. After cultivation for 9 days, the bacteria conc entration reached 4.6?109 MPN/mL and all NO-_2-N in the medium w as converted to NO-_3-N. But the transformation of nitrogen sources was inhibited while the sodium chloride concentration exceeded 0.5% or glucose con centration exceeded 0.1%. According to the test of NO-_2-N conversion with nitrite-oxidizing bacteria in a freshwater aquaculture pond, NO-_2 -N began to decrease on the third day of the moculation of this bacterium and t he concentration dropped from 1.47mol/L to 0.49mol/L after 18 days at 25℃ and pH 8.6.