The amphipathic helices of Arfrp1 and Arl14 are sufficient to determine subcellular localizations

The subcellular localization of Arf family proteins is generally thought to be determined by their corresponding guanine nucleotide exchange factors. By promoting GTP binding, guanine nucleotide exchange factors induce conformational changes of Arf proteins exposing their N-terminal amphipathic helices, which then insert into the membranes to stabilize the membrane association process. Here, we found that the N-terminal amphipathic motifs of the Golgi-localized Arf family protein, Arfrp1, and the endosome- and plasma membrane–localized Arf family protein, Arl14, play critical roles in spatial determination. Exchanging the amphipathic helix motifs between these two Arf proteins causes the switch of their localizations. Moreover, the amphipathic helices of Arfrp1 and Arl14 are sufficient for cytosolic proteins to be localized into a specific cellular compartment. The spatial determination mediated by the Arfrp1 helix requires its binding partner Sys1. In addition, the residues that are required for the acetylation of the Arfrp1 helix and the myristoylation of the Arl14 helix are important for the specific subcellular localization. Interestingly, Arfrp1 and Arl14 are recruited to their specific cellular compartments independent of GTP binding. Our results demonstrate that the amphipathic motifs of Arfrp1 and Arl14 are sufficient for determining specific subcellular localizations in a GTP-independent manner, suggesting that the membrane association and activation of some Arf proteins are uncoupled.     

MiR-20a-containing exosomes from umbilical cord mesenchymal stem cells alleviates liver ischemia/reperfusion injury

Mesenchymal stem cells (MSCs) have been proved to exert considerable therapeutic effects on ischemia-reperfusion (I/R)-induced injury, but the underlying mechanism remains unknown. In this study, we aimed to explore the potential molecular mechanism underlying the therapeutic effect of MSCs-derived exosome reinforced with miR-20a in reversing liver I/R injury. Quantitative real-time polymerase chain reaction, Western blot, and IHC were carried out to compare the differential expressions of miR-20a, Beclin-I, FAS, Caspase-3, mTOR and P62 in IR rats and normal rats. TUNEL was performed to assess IR-induced apoptosis in IR rats, and luciferase assay was used to confirm the inhibitory effect of miR-20a on Beclin-I and FAS expression. Among the 12 candidate microRNAs (miRNAs), miR-486, miR-25, miR-24, miR-20a,miR-466 and miR-433-3p were significantly downregulated in I/R. In particular, miR-20a, a miRNA highly expressed in umbilical cord-derived mesenchymal stem cells, was proved to bind to the 3ʹ UTR of Beclin-I and FAS to exert an inhibitory effect on their expressions. Since Beclin-I and FAS were aberrantly upregulated in IR, exosomes separated from UC-MSCs showed therapeutic efficacy in reversing I/R induced apoptosis. In addition, exosomes reinforced with miR-20a and separated from UC-MSCs almost fully alleviated I/R injury. Furthermore, our results showed that miR-20a could alleviate the abnormal expression of genes related to apoptosis and autophagy, such as active Caspase-3, mTOR, P62, and LC3II. This study presented detailed evidence to clarify the mechanism underlying the therapeutic efficacy of UC-MSCs in the treatment of I/R injury.     

Long noncoding RNA LINC00319 regulates ROMO1 expression and promotes bladder cancer progression via miR-4492/ROMO1 axis

Growing reports indicate that long noncoding RNA (lncRNA) are involved in the regulation of various biological processes of cancer cells. LINC00319 is an ill investigated lncRNA and has been shown to regulate lung cancer, nasopharyngeal carcinoma and ovarian cancer. Nevertheless, its roles in bladder cancer (BCa) remain unclear. In our research, LINC00319 was shown to be an upregulated lncRNA in BCa tissues. LINC00319 expression is negatively correlated with the patient's prognosis. Silencing of LINC00319 suppressed BCa proliferation and invasiveness. In addition, the data indicated LINC00319 was a sponge for miR-4492 and miR-4492 suppressed ROMO1 expression in BCa. Furthermore, our results illustrated miR-4492/ROMO1 axis regulates proliferation, migration, and invasion and LINC00319 exerts oncogenic roles through modulating miR-4492/ROMO1 axis. In sum, this study suggested that LINC00319 acts as oncogenic roles in BCa progression.     

Expression and characterization of chimeric spidroins from flagelliform-aciniform repetitive modules

Spiders can produce up to seven different types of silks or glues with different mechanical properties. Of these, flagelliform (Flag) silk is the most elastic, and aciniform (AcSp1) silk is the toughest. To produce a chimeric spider silk (spidroin) Flag_R-AcSp1_R, we fused one repetitive module of flagelliform silk from Araneus ventricosus and one repetitive module of aciniform silk from Argiope trifasciata. The recombinant protein expressed in E. coli formed silk-like fibers by manual-drawing. CD analysis showed that the secondary structure of Flag_R-AcSp1_R spidroin remained stable during the gradual reduction of pH from 7.0 to 5.5. The spectrum of FTIR indicated that the secondary structure of Flag_R-AcSp1_R changed from α-helix to β-sheet. The conformation change of Flag_R-AcSp1_R was similar to other spidroins in the fiber formation process. SEM analysis revealed that the mean diameter of the fibers was around 1 ~ 2 μm, and the surface was smooth and uniform. The chimeric fibers exhibited superior toughness (~33.1 MJ/m³) and tensile strength (~261.4 MPa). This study provides new insight into design of chimeric spider silks with high mechanical properties.     

Highly efficient production of diverse rare ginsenosides using combinatorial biotechnology

The rare ginsenosides are recognized as the functionalized molecules after the oral administration of Panax ginseng and its products. The sources of rare ginsenosides are extremely limited because of low ginsenoside contents in wild plants, hindering their application in functional foods and drugs. We developed an effective combinatorial biotechnology approach including tissue culture, immobilization, and hydrolyzation methods. Rh2 and nine other rare ginsenosides were produced by methyl jasmonate-induced culture of adventitious roots in a 10 L bioreactor associated with enzymatic hydrolysis using six β-glycosidases and their combination with yields ranging from 5.54 to 32.66 mg L⁻¹. The yield of Rh2 was furthermore increased by 7% by using immobilized BglPm and Bgp1 in optimized pH and temperature conditions, with the highest yield reaching 51.17 mg L⁻¹ (17.06% of protopanaxadiol-type ginsenosides mixture). Our combinatorial biotechnology method provides a highly efficient approach to acquiring diverse rare ginsenosides, replacing direct extraction from Panax plants, and can also be used to supplement yeast cell factories.     

A mass spectrometry-based high-throughput screening method for engineering fatty acid synthases with improved production of medium-chain fatty acids

Microbial cell factories have been extensively engineered to produce free fatty acids (FFAs) as key components of crucial nutrients, soaps, industrial chemicals, and fuels. However, our ability to control the composition of microbially synthesized FFAs is still limited, particularly, for producing medium-chain fatty acids (MCFAs). This is mainly due to the lack of high-throughput approaches for FFA analysis to engineer enzymes with desirable product specificity. Here we report a mass spectrometry (MS)-based method for rapid profiling of MCFAs in Saccharomyces cerevisiae by using membrane lipids as a proxy. In particular, matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) MS was used to detect shorter acyl chain phosphatidylcholines from membrane lipids and a higher m/z peak ratio at 730 and 758 was used as an indication for improved MCFA production. This colony-based method can be performed at a rate of ~2 s per sample, representing a substantial improvement over gas chromatography-MS (typically >30 min per sample) as the gold standard method for FFA detection. To demonstrate the power of this method, we performed site-saturation mutagenesis of the yeast fatty acid synthase and identified nine missense mutations that resulted in improved MCFA production relative to the wild-type strain. Colony-based MALDI-ToF MS screening provides an effective approach for engineering microbial fatty acid compositions in a high-throughput manner.     

Profiling and integrated analysis of differentially expressed circRNAs as novel biomarkers for breast cancer

Breast cancer (BC) is a globally common cancer with the highest and increasing morbidity and mortality among females. Novel biomarkers are warranted to be discovered for the early detection, treatment, and prognosis of BC. In this study, we investigated the profiles of differentially expressed (DE) circular RNAs (circRNAs) by competing endogenous RNAs (ceRNA) microarray to construct a genome-wide circRNA profile. Then, we performed Gene Ontology (GO) analysis and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway analysis of the host genes (HGs) of circRNAs. A total of 4,370 DE circRNAs were detected and GO and KEGG analysis showed that they were significantly associated with cell cycle, DNA replication, BC, and familial BC. We validated the differential circRNAs and relevant HGs through quantitative real-time polymerase chain reaction and constructed a putative circRNA–microRNA–messenger RNA regulatory network. Eight circRNAs, including hsa_circ_0069094, hsa_circ_0062558, hsa_circ_0074026, hsa_circ_0079876, hsa_circ_0017536, hsa_circ_0023302, hsa_circ_0017650, and hsa_circ_0017545, were validated significantly DE in BC tissue and associated with TNM staging, lymph node infiltration, and Ki67. Hsa_circ_0069094, hsa_circ_0079876, hsa_circ_0017650, and hsa_circ_0017526 were upregulated in plasma. This study revealed the general expression characteristics of specific DE circRNAs in BC and hsa_circ_0069094, hsa_circ_0079876, hsa_circ_0017650, and hsa_circ_0017526 might be promising candidate targets.     

Astragalus polysaccharides alleviates LPS-induced inflammation via the NF-κB/MAPK signaling pathway

Early weaning usually causes intestinal disorders, enteritis, and diarrhea in young animals and human infants. Astragalus polysaccharides (APS) possesses anti-inflammatory activity. To study the anti-inflammatory mechanisms of APS and its potential effects on intestinal health, we performed an RNA sequencing (RNA-seq) study in lipopolysaccharide (LPS)-stimulated porcine intestinal epithelial cells (IPEC-J2) in vitro. In addition, LPS-stimulated BALB/c mice were used to study the effects of APS on intestinal inflammation in vivo. The results from the RNA-seq analysis show that there were 107, 756, and 5 differentially expressed genes in the control versus LPS, LPS versus LPS+APS, and control versus LPS+APS comparison groups, respectively. The results of Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways play significant roles in the regulation of inflammatory factors and chemokine expression by APS. Further verification of the above two pathways by using western blot and immunofluorescence analysis revealed that the gene expression levels of the phosphorylated p38 MAPK, ERK1/2, and NF-κB p65 were inhibited by APS, while the expression of IκB-α protein was significantly increased (p < .05), indicating that APS inhibits the production of inflammatory factors and chemokines by the inhibition of activation of the MAPK and NF-κB inflammatory pathways induced by LPS stimulation. Animal experiments further demonstrated that prefeeding APS in BALB/c mice can alleviate the expression of the jejunal inflammatory factors interleukin 6 (IL-6), IL-Iβ, and tumor necrosis factor-α induced by LPS stimulation and improve jejunal villus morphology.     

SOX2-induced upregulation of lncRNA LINC01561 promotes non-small-cell lung carcinoma progression by sponging miR-760 to modulate SHCBP1 expression

Long noncoding RNAs (lncRNAs) have been shown to have critical regulatory roles in tumorigenesis. lncRNA LINC01561 (LINC01561) is a newly identified tumor-related lncRNA and its dysregulation has been demonstrated in several tumors. However, whether LINC01561 is involved in the progression of non-small-cell lung carcinoma (NSCLC) and its underlying mechanisms remain unknown. In this study, we first provided evidence that LINC01561 expressions were distinctly upregulated in NSCLC tissues and cell lines. Combining with bioinformatics assays and mechanism experiments, our group demonstrated that LINC01561 was activated by SOX2 in NSCLC. Clinical research revealed that upregulation of LINC01561 was related to poorer clinicopathologic features and shorter survival time. Functionally, suppression of LINC01561 exhibited tumor-suppressive functions through impairing cell proliferation, migration, and invasion as well as inducing apoptosis. Moreover, we verified that LINC01561 could directly bind to miR-760, isolating miR-760 from its target gene SHC SH2 domain-binding protein 1 (SHCBP1). We also found that SHCBP1 was lowly expressed in NSCLC and served as a tumor promoter. A functional study indicated that LINC01561 regulated SHCBP1 expression by competitively binding to miR-760. In summary, our findings indicated that SOX2-induced overexpression of LINC01561 promoted the proliferation and metastasis by acting as a competing endogenous RNA to modulate SHCBP1 by sponging miR-760.