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Background: Hypoxia is a hallmark of the physical microenvironment of solid tumors. As a key factor that regulates tumor development and progression, hypoxia can reprogram the expression of multiple genes, whose biological function and molecular mechanism in cancer remain largely unclear. The mitochondrial ribosome protein family consists of nuclear-encoded mitochondrial proteins that are responsible for protein synthesis in the mitochondria. Methods: A high-throughput RNA sequencing assay was carried out to identify differentially expressed mRNAs between breast cancer tissues and adjacent normal tissues as well as breast tumors with metastasis and those without metastasis. Our clinical samples and TCGA database were analyzed to observe the clinical value of mitochondrial ribosome protein L52 (MRPL52) in human breast cancer. Potent hypoxia response elements in the promoter region of MRPL52 were identified and validated by chromatin immunoprecipitation and luciferase reporter assays. Functional experiments were performed using breast cancer cell lines with MRPL52 ectopic expression and knockdown cultured in a 20% or 1% O2 environment. Results: MRPL52 expression was upregulated in human breast cancer and was significantly associated with aggressive clinicopathological characteristics and a higher metastatic risk of breast cancer patients. We found that the overexpression of MRPL52 in breast cancer is induced by hypoxia-inducible factor-1 in response to hypoxic exposure. The role of MRPL52 in suppressing apoptosis and promoting migration and invasion of hypoxic breast cancer cells was demonstrated by our experimental evidence. Mechanistically, MRPL52 promoted PTEN-induced putative kinase 1 /Parkin-dependent mitophagy to remove oxidatively damaged mitochondria and prevent uncontrolled reactive oxygen species (ROS) generation, thus repressing activation of the mitochondrial apoptotic cascade. Additionally, MRPL52 augmented epithelial-mesenchymal transition, migration and invasion of hypoxic breast cancer cells by activating the ROS-Notch1-Snail signaling pathway. Benefited from this bidirectional regulatory mechanism, MRPL52 is responsible for maintaining ROS levels in a window that can induce tumorigenic signal transduction without causing cytotoxicity in hypoxic breast cancer cells. Conclusions: This work elucidates the molecular mechanism by which MRPL52 mediates hypoxia-induced apoptotic resistance and metastatic initiation of breast cancer, and provides new insights into the interplay between cancer and the tumor microenvironment.

Rationale Myocardial infarction (MI) is a leading cause of cardiovascular mortality globally. The improvement of microvascular function is critical for cardiac repair after MI. Evidence now points to long non-coding RNAs (lncRNAs) as key regulators of cardiac remodelling processes. The lncRNA Malat1 is involved in the development and progression of multiple cardiac diseases. Studies have shown that Malat1 is closely related to the regulation of endothelial cell regeneration. However, the potential molecular mechanisms of Malat1 in repairing cardiac microvascular dysfunction after MI remain unreported. Methods and results The present study found that Malat1 is upregulated in the border zone of infarction in mouse hearts, as well as in isolated cardiac microvascular endothelial cells (CMECs). Targeted knockdown of Malat1 in endothelial cells exacerbated oxidative stress, attenuated angiogenesis and microvascular perfusion, and as a result decreased cardiac function in MI mice. Further studies showed that silencing Malat1 obviously inhibited CMEC proliferation, migration and tube formation, which was at least in part attributed to disturbed mitochondrial dynamics and activation of the mitochondrial apoptosis pathway. Moreover, bioinformatic analyses, luciferase assays and pull-down assays indicated that Malat1 acted as a competing endogenous RNA (ceRNA) for miR-26b-5p and formed a signalling axis with Mfn1 to regulate mitochondrial dynamics and endothelial functions. Overexpression of Mfn1 markedly reversed the microvascular dysfunction and CMEC injuries that were aggravated by silencing Malat1 via inhibition of excessive mitochondrial fragments and mitochondria-dependent apoptosis. Conclusions The present study elucidated the functions and mechanisms of Malat1 in cardiac microcirculation repair after MI. The underlying mechanisms of the effects of Malat1 could be attributed to its blocking effects on miR-26b-5p/Mfn1 pathway-mediated mitochondrial dynamics and apoptosis.

MicroRNA-27a (miR-27a) has been implicated in myocardial ischemia-reperfusion injury (MIRI), but the underlying mechanism is not well understood. This study is aimed at determining the role of miR-27a in MIRI and at investigating upstream molecules that regulate miR-27a expression and its downstream target genes. miR-27a expression was significantly upregulated in myocardia exposed to ischemia/reperfusion (I/R) and cardiomyocytes exposed to hypoxia/reoxygenation (H/R). c-Fos could regulate miR-27a expression by binding to its promoter region. Moreover, overexpression of miR-27a led to a decrease in cell viability, an increase in LDH and CK-MB secretion, and an increase in apoptosis rates. In contrast, suppression of miR-27a expression resulted in the opposite effects. ATPase family AAA-domain-containing protein 3A (ATAD3a) was identified as a target of miR-27a. miR-27a regulated the translocation of apoptosis-inducing factor (AIF) from the mitochondria to the nucleus and H/R-induced apoptosis via the regulation of ATAD3a. It was found that inhibiting miR-27a in vivo by injecting a miR-27a sponge could ameliorate MIRI in an isolated rat heart model. In conclusion, our study demonstrated that c-Fos functions as an upstream regulator of miR-27a and that miR-27a regulates the translocation of AIF from the mitochondria to the nucleus by targeting ATAD3a, thereby contributing to MIRI. These findings provide new insight into the role of the c-Fos/miR-27a/ATAD3a axis in MIRI.

Oxidative stress aggravates mitochondrial injuries and accelerates the proliferation of vascular smooth muscle cells (VSMCs), which are important mechanisms contributing to vascular remodeling in hypertension. We put forward the hypothesis that Astaxanthin (ATX), known to possess strong features of antioxidant, could attenuate vascular remodeling by inhibiting VSMC proliferation and improving mitochondrial function. The potential effects of ATX were tested on spontaneously hypertensive rats (SHRs) and cultured VSMCs that injured by angiotensin II (Ang II). The results showed that ATX lowered blood pressure, reduced aortic wall thickness and fibrosis, and decreased the level of reactive oxygen species (ROS) and H2O2 in tunica media. Moreover, ATX decreased the expression of proliferating cell nuclear antigen (PCNA) and ki67 in aortic VSMCs. In vitro, ATX mitigated VSMC proliferation and migration, decreased the level of cellular ROS, and balanced the activities of ROS-related enzymes including NADPH oxidase, xanthine oxidase, and superoxide dismutase (SOD). Besides, ATX mitigated Ca2+ overload, the overproduction of mitochondrial ROS (mtROS), mitochondrial dysfunction, mitochondrial fission, and Drp1 phosphorylation at Ser616. In addition, ATX enhanced mitophagy and mitochondrial biosynthesis by increasing the expression of PINK, parkin, mtDNA, mitochondrial transcription factor A (Tfam), and PGC-1α. The present study indicated that ATX could efficiently treat vascular remodeling through restraining VSMC proliferation and restoring mitochondrial function. Inhibiting mitochondrial fission by decreasing the phosphorylation of Drp1 and stimulating mitochondrial autophagy and biosynthesis via increasing the expression of PINK, parkin, Tfam, and PGC-1α may be part of its underlying mechanisms.

The influence mechanism of different withering methods (CK, indoor natural spreading; LTD, low-temperature plus dark; LTY, low-temperature plus yellow-light; LTCD, low-temperature plus CO2) on non-volatile compounds in postharvest tea leaves was investigated by UHPLC-Q-TOF/MS-based non-targeted metabolomic and transcriptomic analyses. Compared with CK, low-temperature withering could slow down polyphenol oxidation by inhibiting polyphenol oxidase activity and keeping the expression of genes for flavanol synthesis. After withering, the proteinaceous amino acid content increased significantly, especially for LTCD and LTY, mainly due to increased peptidase activity and up-regulation of genes involved in the biosynthesis of valine, leucine, aspartic acid, glutamic acid, phenylalanine, and proline. Moreover, LTCD and LTY enhanced the synthesis of γ-aminobutyric acid and metabolism of phenylalanine-methyl salicylate and tryptophan-indole, respectively. Meanwhile, the transformation of theobromine to caffeine was accelerated under low-temperature withering. This research provides ageneticmetabolicbasis for the application of low-temperature withering to actual green tea processing.

The aim of the present study was to determine whether curculigoside protects against myocardial ischemia-reperfusion injury (MIRI) and to investigate the underlying mechanisms. An in vitro model of hypoxia/reoxygenation (H/R) was established by culturing H9c2 cells under hypoxic conditions for 12 h, followed by reoxygenation for 1 h. Cell Counting kit-8 and lactate dehydrogenase (LDH) assays were subsequently used to examine cell viability and the degree of cell injury. In addition, isolated rat hearts were subjected to 30 min of ischemia followed by 1 h of reperfusion to establish a MIRI model. Triphenyltetrazolium chloride (TTC) staining was performed to measure the infarct size. Furthermore, TUNEL staining and flow cytometry were employed to evaluate cell apoptosis. The opening of the mitochondrial permeability transition pore (MPTP) and changes in the mitochondrial membrane potential (ΔΨm) were assessed. Reverse transcription-quantitative PCR and western blot analysis were performed to investigate the expression levels of mitochondrial apoptosis-related proteins. Curculigoside pre-treatment significantly improved cell viability, decreased cell apoptosis and LDH activity, and reduced the infarct size and myocardial apoptosis in vitro and ex vivo, respectively. Moreover, curculigoside markedly inhibited MPTP opening and preserved the ΔΨm. In addition, curculigoside significantly decreased the expression of cytochrome c, apoptotic protease activating factor-1, cleaved caspase-9 and cleaved caspase-3. Notably, atractyloside, a known MPTP opener, abrogated the protective effects of curculigoside. On the whole, the present study demonstrated that curculigoside protected against MIRI, potentially by decreasing the levels of mitochondria-mediated apoptosis via the inhibition of MPTP opening. Therefore, the results obtained in the present study may provide the theoretical basis for the future clinical application of curculigoside.

This study focused on non-targeted metabolomics analysis of the relationship of the chemical composition, quality traits, bioactivity of black tea (Camellia sinensis L.) with five withering degrees (WD65, WD60, WD55, WD50, and WD45, corresponding to 65, 60, 55, 50, and 45% water content in withered leaves, respectively) and their effects on sensory quality traits. WD60 was shown as the optimal withering degree (WD) with the highest total quality score (89.7), followed by WD55 (88.7). With increasing WD, the content of most volatile components increased significantly, but with no significant difference between some substances below WD55. The total amount of free amino acids increased with increasing WD, in contrast to a decrease in the total amount of catechins, flavonoids/flavonoid glycosides, theaflavins and glycosidically bound volatiles (GBVs). Black tea with a WD between WD65 and WD60 was shown to have higher antioxidant activity and stronger inhibitory effect on α-amylase and α-glucosidase activity or intestinal glucose uptake. The overall data indicate that WD60 treatment not only benefits the formation of sensory quality traits, but also shows better bioactivity.

Aim Oxidative stress plays an important role in myocardial ischemia-reperfusion injury. Pleckstrin homology-like domain, family A, member 1 (PHLDA1) was first identified in apoptosis induced by T cell receptor activation, and was shown to play a different role in different cell types and under different stimuli. The role and mechanism of PHLDA1 in oxidative stress-induced cardiomyocyte injury and cardiac ischemia-reperfusion were therefore determined. Main methods Cell viability and apoptotic rate were measured by Cell Counting Kit-8 and flow cytometry, respectively. Mitochondrial membrane potential was measured using JC-1 test kit. Reactive oxygen species (ROS) production was detected using ROS kit. HE staining was used to detect histological morphology, 2,3,5-triphenyltetrazolium chloride staining to detect infarct size, terminal deoxynucleotidyl transferase dUTP nick end labeling staining to detect the apoptotic rate, and immunohistochemistry and western blot analysis to detect protein expression. The binding of PHLDA1 to Bcl-2 associated X (Bax) was detected by immunoprecipitation. Key findings The results indicated that PHLDA1 is highly expressed in oxidative stress-induced cardiomyocyte and myocardial ischemia-reperfusion injuries. PHLDA1 overexpression in cardiomyocytes promoted oxidative stress-induced cardiomyocyte injury. At the same time, PHLDA1 knockdown improved oxidative stress-induced cardiomyocyte and myocardial ischemia-reperfusion injuries. In addition, PHLDA1 binds to Bax and the interaction is enhanced under H2O2 stimulation. Significance The present results indicated that PHLDA1 interacts with Bax to participate in oxidative stress-induced cardiomyocyte injury and myocardial ischemia reperfusion injury.

This study aimed to figure out the optimum fermentation temperature by analyzing the major chemical constituents of black tea and its antioxidant activities, inhibitory activities against α-amylase, α-glucosidase and glucose uptake. Sensory evaluation revealed 28°C-fermented black tea showed best sensory quality with highest scores for aroma (6.5) and taste (29.8). With increasing fermentation temperature, polyphenols, polysaccharides, (−)-epigallocatechin, (+)-catechin, theaflavins and thearubigins decreased significantly, while amino acids, soluble sugars and volatiles increased when temperature increased up to 31 °C. Furthermore, black tea fermented at 28 °C showed strongest DPPH radical scavenging ability, anti-lipid peroxidation and inhibitory effect on α-glucosidase activity with IC50 value of 17.72 μg/mL, 1.49 mg/mL and 21.69 μg/mL respectively. While 25°C-fermented black tea showed highest inhibition rate of glucose uptake in Caco-2 cells. The results demonstrate that appropriately lowering fermentation temperature could improve both sensory quality and bioactivity of black tea.

SCOPE Na+ /K+ -ATPase is an important membrane-bound enzyme and high levels of Na+ /K+ -ATPase activity in intestine result in increased monosaccharide absorption and aggravated undesirable postprandial hyperglycemia in diabetic. The aim is to characterize the effects of green and black tea extracts on the intestinal Na+ /K+ -ATPase. METHODS AND RESULTS The STZ-induced type 1 diabetic mice model and high-fat diet combined with low-dose STZ-induced type 2 diabetic mice model are used in this study and the data indicate that both green and black tea extracts show significant hypoglycemic effect. The Na+ /K+ -ATPase activities in intestine associated with glucose absorption are increased in type 1 diabetic mice, while those are even normal in type 2 diabetic mice. Green and black tea extracts can attenuate type 1 diabetes-induced intestinal Na+ /K+ -ATPase disturbance to control postprandial hyperglycemia. Black tea is more effective than green tea in reducing of Na+ /K+ -ATPase activity and protein expression. Theaflavins are the major functional components of black tea and theaflavine-3,3'-digallate presents the strongest inhibitory effect exhibiting anticompetition with ATP and mixed inhibition with Na+ and K+ . CONCLUSION Tea, especially black tea, can be considered a potential therapeutic agent against type 1 diabetes-induced intestinal Na+ /K+ -ATPase disturbance to control postprandial hyperglycemia.

Six Green tea powders (GTPs) were prepared from green tea with superfine grinding process. Their main quality components were determined by chemical methods and the scavenging effects of GTPs on ·OH and O2.− in vitro were evaluated by using deoxyribose assay and xanthine oxidase method, respectively. The results indicated that tea polyphenols and catechins contents decreased, while the contents of water-soluble carbohydrates in GTPs increased markedly, and no significant difference in amino acids and caffein with the decrease in particle size during superfine grinding, which benefited to reduce bitterness and preserve briskness of GTPs. Meanwhile, superfine grinding increased extraction of TPS markedly, which could lead to more potent scavenging capacity of GTPEs on ·OH. Based on the above analysis, it suggested that superfine grinding time should be controlled within 30–50 min, with ideal parameters of GTP: X: 4.93–4.75%, d50: 20.3–13.5 μm, ρbulk: 0.323–0.297 kg/m3, ρtapped: 0.666–0.614 kg/m3. Under this condition, we could prepare GTP with green and bright color, narrower and more uniform particle size distribution, as well as possessing more food processing property.

In the present work, Qingzhuan tea, a unique dark tea produced by post-fermentation technology, was selected to investigate its antioxidant and pancreatic α-amylase inhibiting activities. Water extract of Qingzhuan tea was successively isolated by solvent partitioning procedures to obtain chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions. Of different fractions, the ethyl acetate fraction (QEF) had the highest total polyphenols and catechins contents, demonstrated the strongest DPPH radical scavenging activity and exhibited the greatest inhibitory effect on porcine pancreatic α-amylase activity in vitro. Further separation of QEF by a Sephadex LH-20 column generated eight subfractions (QEF1–QEF8), with QEF8 being the most active subfraction based on the assays above mentioned. The major active components in QEF8 were identified as catechins EGCG and ECG by LC-MS analysis, with contents of 22.29 % and 11.11 % respectively. Inhibitory effects of catechin standards EGCG and ECG on porcine pancreatic α-amylase activity were also observed. In conclusion, Qingzhuan tea or its water extract could be potentially used as complementary therapy ingredients for diabetes treatment through lowering postprandial blood glucose, and catechins EGCG and ECG may be the most efficient components in the water extract.

The present study investigated effects of solvents, temperature, and duration on extracting efficiency of catechins from green tea by an orthogonal test. The results suggested that extraction of epigallocatechin gallate (EGCG) was highly dependent on these factors, whereas that of epigallocatechin (EGC) was significantly affected by duration and solvent (P0.05). Effects of these factors on epicatechin (EC), catechin (C), and epicatechin gallate (ECG) were not significant. A two-step preparation was adopted to produce green tea extract enriched in EGC (GTE-EGC) and green tea extract enriched in EGCG (GTE-EGCG). The optimum conditions for GTE-EGC were that green tea was brewed in 75% ethanol at 30 degrees C for 10 min, whereas for GTE-EGCG the same tea was brewed in 35% ethanol at 90 degrees C for 60 min. Compared with GTE-EGC, GTE-EGCG had EGCG increased by 110.42%, whereas EGC decreased by 40.38% with EC and ECG being unchanged. Most importantly, GTE-EGCG possessed greater antioxidant activity (in vitro) than GTE-EGC.