The function and mechanism of lactate and lactylation in tumor metabolism and microenvironment.

Lactate is an end product of glycolysis. Owing to the lactate shuttle concept introduced in the early 1980s, increasing researchers indicate lactate as a critical energy source for mitochondrial respiration and as a precursor of gluconeogenesis. Lactate also acts as a multifunctional signaling molecule through receptors expressed in various cells, resulting in diverse biological consequences including decreased lipolysis, immune regulation, and anti-inflammation wound healing, and enhanced exercise performance in association with the gut microbiome. Furthermore, increasing evidence reveals that lactate contributes to epigenetic gene regulation by lactylating lysine residues of histones, which accounts for its key role in immune modulation and maintenance of homeostasis. Here, we summarize the function and mechanism of lactate and lactylation in tumor metabolism and microenvironment.

Magnetoresistance of Ni/WSe2/Ni junctions: robustness against the thickness of WSe2.

Magnetoresistive materials are vital for the development of storage devices. Using the first-principles transport simulations with nonequilibrium Green's function calculation, we investigate the magnetoresistive properties of Ni/WSe2/Ni junctions withm-layers of WSe2(m= 1, 2, ⋯ ,6). Form≤ 2, the junctions are metallic inspite of the semiconducting nature of few-layer WSe2. However, the junctions exhibit transport gaps form> 2. Interestingly, magnetoresistance of the junctions stays around 6% when there are more than one layer of WSe2in the center, which is closely related to the robust spacial variation of interfacial properties and can be attributed to no spin flipping in tunneling regions. Our results suggest that Ni/WSe2/Ni junctions have a robust magnetoresistance which is insensitive to the thickness of WSe2.

High Concentration of Glial Cell Line-Derived Neurotrophic Factor Protects Primary Astrocytes from Apoptosis.

BACKGROUND: Studies have shown that astrocytes play an important role in a variety of biological processes, so damage to astrocytes can cause a series of related diseases. Glial cell line-derived neurotrophic factor (GDNF) has always been considered a protective factor for dopamine neurons. However, it remains unclear whether GDNF has a protective effect on glial cells, especially astrocytes. In this study, we put forward the hypothesis that a high concentration of GDNF in the microenvironment of astrocytes exerts an inhibitory effect on the apoptosis of astrocytes by DNA-damaging reagents. METHODS: We isolated, purified, and identified primary astrocytes from neonate rats. Astrocytes were exposed to mitoxantrone (MTN, a DNA-damaging compound) for 24 h. The effects of MTN on astrocytes were tested by Hoechst 33342 staining, CCK-8 assay, and flow cytometry assay. One of the concentrations of MTN was applied to construct an apoptotic model of astrocytes. The astrocytes were then treated with GDNF together with a selected concentration of MTN for 24 h. The cell viability, cell nucleus morphology, and apoptosis ratio of the cells was assessed by Hoechst 33342 staining, CCK-8 assay, and flow cytometry assay, respectively. RNA sequencing (RNA-Seq), quantitative PCR analysis, and KEGG pathway mapping were performed to examine the genes involved in the procedure. Finally, Western blot analysis was applied to confirm the expression levels of the proteins of interest. RESULTS: Hoechst 33342 staining revealed a one-tenth change in the percentage of Hoechst-positive cells after the addition of 500 ng/mL GDNF combined with 1,000 nM MTN for 24 h. The viability of the cells treated the same as described above was 1.4-fold that of the control group. Flow cytometry assays indicated that the apoptotic rates were 17.67, 8.67, and 4.34% for 0, 200, and 500 ng/mL GDNF, respectively. Birc2, Birc3, and Gadd45b were linked to the antiapoptotic process induced by GDNF in astrocytes. Western blot analysis confirmed the elevated expression of Birc2 and Gadd45b. CONCLUSIONS: Our studies revealed that GDNF has a noticeable antiapoptotic effect on gene-injured astrocytes. This may provide critical clues for the treatment of a series of diseases in which damaged astrocytes are involved.

Precursor N-cadherin mediates glial cell line-derived neurotrophic factor-promoted human malignant glioma.

As the most prevalent primary brain tumor, gliomas are highly metastatic, invasive and are characteristic of high levels of glial cell-line derived neurotrophic factor (GDNF). GDNF is an important factor for invasive glioma cell growth; however, the underlying mechanism involved is unclear. In this study, we affirm a significantly higher expression of the precursor of N-cadherin (proN-cadherin) in most gliomas compared with normal brain tissues. Our findings reveal that GDNF interacts with the extracellular domain of proN-cadherin, which suggests that proN-cadherin mediates GDNF-induced glioma cell migration and invasion. We hypothesize that proN-cadherin might cause homotypic adhesion loss within neighboring cells and at the same time promote heterotypic adhesion within the extracellular matrix (ECM) through a certain mechanism. This study also demonstrates that the interaction between GDNF and proN-cadherin activates specific intracellular signaling pathways; furthermore, GDNF promoted the secretion of matrix metalloproteinase-9 (MMP-9), which degrades the ECM via proN-cadherin. To reach the future goal of developing novel therapies of glioma, this study, reveals a unique mechanism of glioma cell migration and invasion.

The complete mitochondrial genome of the Placidochromis longimanus.

The Placidochromis longimanus (P. longimanus), one species of Cichlidae, resides in the Lake Malawi in East Africa. In present study, for the first time, we reported the complete mitochondrial genome of P. longimanus, which has 16 581 bp in length, including 13 protein-coding genes, 2 ribosomal RNA, 22 transfer RNA genes, and 1 control zone. Moreover, its GC content is 45.99% (27.44% A, 26.58% T, 30.11% C, and 15.87% G), similar to that of Astatotilapia calliptera (the GC content of 45.90%). We further made the phylogenetic tree on the complete mitochondrial genomes of the above two species and other 11 closely related species to show their phylogenic relationship. The above results would facilitate our understanding of the evolution of Cichlidae mitochondrial genome.

High-level expression and purification of soluble recombinant FGF21 protein by SUMO fusion in Escherichia coli.

BACKGROUND: Fibroblast growth factor 21 (FGF21) is a promising drug candidate to combat metabolic diseases. However, high-level expression and purification of recombinant FGF21 (rFGF21) in Escherichia coli (E. coli) is difficult because rFGF21 forms inclusion bodies in the bacteria making it difficult to purify and obtain high concentrations of bioactive rFGF21. To overcome this problem, we fused the FGF21 with SUMO (Small ubiquitin-related modifier) by polymerase chain reaction (PCR), and expressed the fused gene in E. coli BL21(DE3). RESULTS: By inducing with IPTG, SUMO-FGF21 was expressed at a high level. Its concentration reached 30% of total protein, and exceeded 95% of all soluble proteins. The fused protein was purified by DEAE sepharose FF and Ni-NTA affinity chromatography. Once cleaved by the SUMO protease, the purity of rFGF21 by high performance liquid chromatography (HPLC) was shown to be higher than 96% with low endotoxin level (<1.0 EU/ml). The results of in vivo animal experiments showed that rFGF21 produced by using this method, could decrease the concentration of plasma glucose in diabetic rats by streptozotocin (STZ) injection. CONCLUSIONS: This study demonstrated that SUMO, when fused with FGF21, was able to promote its soluble expression of the latter in E. coli, making it more convenient to purify rFGF21 than previously. This may be a better method to produce rFGF21 for pharmaceutical research and development.

A general and efficient approach to aryl thiols: CuI-catalyzed coupling of aryl iodides with sulfur and subsequent reduction.

A CuI-catalyzed coupling reaction of aryl iodides and sulfur powder takes place in the presence of K(2)CO(3) at 90 degrees C. The coupling mixture is directly treated with NaBH(4) or triphenylphosphine to afford aryl thiols in good to excellent yields. A wide range of substituted aryl thiols that bear methoxy, hydroxyl, carboxylate, amido, keto, bromo, and fluoro groups can be assembled through this procedure.

Biotransformation of ginsenoside Rf to Rh1 by recombinant beta-glucosidase.

An Aspergillus niger strain was isolated from the soil around ginseng fruit. In vitro enzyme assays showed that this strain had the ability to transform total ginsenosides (TGS) into several new products. In a further biochemical study, a beta-glucosidase gene isolated from this strain, bgl1, was expressed in Saccharomyces cerevisiae. His-tagged BGL1 protein (approximately 170 kD) showed the ability to transform ginsenoside Rf into Rh(1).

Preparation of the diphenylcarbazone-functionalized silica gel and its application to on-line selective solid-phase extraction and determination of mercury by flow-injection spectrophotometry.

A new solid-phase extractor, diphenylcarbazone-functionalized silica gel has been synthesized and confirmed by IR and Raman spectrometry. The new solid-phase extractor is found to be stable in 1-6 mol L(-1) HCl or H(2)SO(4), and also in common organic solvents. It can be used to separate and enrich Hg(II) selectively from eight metal ions with similar characteristics such as Cd(II), Ni(II), Co(II), Mn(II), Pb(II), Zn(II), Cu(II) and Fe(III). The pre-concentration factor is as high as 500. The results show that this new solid extractor has a good stability and can be reused for many times without decreasing its extraction percentage. The micro-column packed with diphenylcarbazone-functionalized silica gel was used for on-line solid-phase extraction and determination of mercury in real samples by flow-injection spectrophotometry. At the optimal conditions, the linear range and the detection limit for the determination of Hg(II) is found to be 1-1500 and 0.90 ng mL(-1), respectively. The relative standard deviation of 11 replicate measurements is less than 3%. The proposed method was demonstrated to be simple, fast, selective, low cost and less pollution.