Background and Aims
Circular RNAs (circRNAs) and extracellular vesicles (EVs) are involved in various malignancies. We aimed to clarify the functions and mechanisms of dysregulated circRNAs in the cells and EVs of cholangiocarcinoma (CCA).
Approach and Results
CircRNA microarray was used to identify circRNA expression profiles in CCA tissues and bile‐derived EVs (BEVs). CCA‐associated circRNA 1 (circ‐CCAC1) expression was measured by quantitative real‐time PCR. The clinical importance of circ‐CCAC1 was analyzed by receiver operating characteristic curves, Fisher’s exact test, Kaplan–Meier plots, and Cox regression model. The functions of circ‐CCAC1 and exosomal circ‐CCAC1 were explored in CCA cells and human umbilical vein endothelial cells (HUVECs), respectively. Different animal models were used to verify the in vitro results. RNA sequencing, bioinformatics, RNA immunoprecipitation, RNA pulldown, chromatin immunoprecipitation followed by sequencing, and luciferase reporter assays were used to determine the regulatory networks of circ‐CCAC1 in CCA cells and HUVECs. Circ‐CCAC1 levels were increased in cancerous bile‐resident EVs and tissues. The diagnostic and prognostic values of circ‐CCAC1 were identified in patients with CCA. For CCA cells, circ‐CCAC1 increased cell progression by sponging miR‐514a‐5p to up‐regulate Yin Yang 1 (YY1). Meanwhile, YY1 directly bound to the promoter of calcium modulating ligand to activate its transcription. Moreover, circ‐CCAC1 from CCA‐derived EVs was transferred to endothelial monolayer cells, disrupting endothelial barrier integrity and inducing angiogenesis. Mechanistically, circ‐CCAC1 increased cell leakiness by sequestering enhancer of zeste homolog 2 in the cytoplasm, thus elevating SH3 domain‐containing GRB2‐like protein 2 expression to reduce the levels of intercellular junction proteins. In vivo studies further showed that increased circ‐CCAC1 levels in circulating EVs and cells accelerated both CCA tumorigenesis and metastasis.
Conclusions
Circ‐CCAC1 plays a vital role in CCA tumorigenesis and metastasis and may be an important biomarker/therapeutic target for CCA.
Lysosomes are degradation and signaling organelles that adapt their biogenesis to meet many different cellular demands; however, it is unknown how lysosomes change their numbers for cell division. Here, we report that the cyclin-dependent kinases CDK4/6 regulate lysosome biogenesis during the cell cycle. Chemical or genetic inactivation of CDK4/6 increases lysosomal numbers by activating the lysosome and autophagy transcription factors TFEB and TFE3. CDK4/6 interact with and phosphorylate TFEB/TFE3 in the nucleus, thereby inactivating them by promoting their shuttling to the cytoplasm. During the cell cycle, lysosome numbers increase in S and G2/M phases when cyclin D turnover diminishes CDK4/6 activity. These findings not only uncover the molecular events that direct the nuclear export of TFEB/TFE3, but also suggest a mechanism that controls lysosome biogenesis in the cell cycle. CDK4/6 inhibitors promote autophagy and lysosome-dependent degradation, which has important implications for the therapy of cancer and lysosome-related disorders.
Multienzymatic
cascade reactions have garnered the attention of
many researchers as an approach for converting CO2 into
methanol. The cascade reaction used in this study includes the following
enzymes: a formate dehydrogenase (ClFDH), a formaldehyde dehydrogenase
(BmFaldDH), and an alcohol dehydrogenase (YADH) from Clostridium ljungdahlii, Burkholderia
multivorans, and Saccharomyces cerevisiae, respectively. Because this cascade reaction requires NADH as a
cofactor, phosphite dehydrogenase (PTDH) was employed to regenerate
the cofactor. The multienzymatic cascade reaction, along with PTDH,
yielded 3.28 mM methanol. The key to the success of this cascade reaction
was a novel formaldehyde dehydrogenase, BmFaldDH, the enzyme catalyzing
the reduction of formate to formaldehyde. The methanol yield was further
improved by incorporation of 1-ethyl-3-methylimidazolium acetate (EMIM-Ac),
resulting in 7.86 mM of methanol. A 500-fold increase in total turnover
number was observed for the ClFDH-BmFaldDH-YADH cascade system compared
to the Candida boidinii FDH-Pseudomonas putida FaldDH-YADH system. We provided
detailed insights into the enzymatic reduction of CO2 by
determining the thermodynamic parameters (K
d and ΔG
) using isothermal
titration calorimetry. Furthermore, we demonstrated a novel time-dependent
formaldehyde production from CO2. Our results will aid
in the understanding and development of a robust multienzyme catalyzed
cascade reaction for the reduction of CO2 to value-added
chemicals.
In recent years, IoV (Internet of Vehicles) has become one of the most active research fields in network and intelligent transportation system. As an open converged network, IoV plays an important role in solving various driving and traffic problems by advanced information and communications technology. We review the existing notions of IoV from different perspectives. Then, we provide our notion from a network point of view and propose a novel IoV architecture with four layers. Particularly, a novel layer named coordinative computing control layer is separated from the application layer. The novel layer is used for solving the coordinative computing and control problems for human-vehicle-environment. After summarizing the key technologies in IoV architecture, we construct a VV (Virtual Vehicle), which is an integrated image of driver and vehicle in networks. VVs can interact with each other in cyber space by providing traffic service and sharing sensing data coordinately, which can solve the communication bottleneck in physical space. Finally, an extended IoV architecture based on VVs is proposed.
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