Prolonged oral intake of green tea polyphenols attenuates delirium-like behaviors in mice induced by anesthesia/surgery.

Postoperative delirium (POD) is a severe postoperative complication characterized by delirium-like symptoms. So far, no effective preventable strategy for POD prevention has been identified. Reports show that the consumption of green tea polyphenols (GTP) is associated with better cognitive function by modulating the composition of gut microbiota. Whether GTP also play a role in alleviating POD through gut microbiota is unknown. Herein, we studied the effect of prolonged (eight weeks) GTP intake on postoperative delirium in C57BL/6 mice with laparotomies under isoflurane anesthesia (anesthesia/surgery). We subsequently investigated anesthesia/surgery caused behavioral changes and increased the expression of malondialdehyde (MAD), an oxidative stress marker, and the activities of superoxide dismutase (SOD), an antioxidant marker, in the mice at 6 h after anesthesia/surgery. However, GTP administration reversed these changes and alleviated anesthesia/surgery-induced decrease in the abundance of gut bacterial genera, Roseburia. Further, fecal microbiota transplant demonstrated that compared with mice in the control group, treatment of C57BL/6 mice with feces from GTP-treated mice had a slight effect on the behavioral changes of mice. These data suggest that daily consumption of GTP could protect against anesthesia/surgery-induced behavioral changes, which is closely associated with gut microbiota modification by GTP.

Prognostic Role of Mitochondrial Transcription Termination Factor 3 in Thyroid Carcinoma.

Background: Studies have shown that the Mitochondrial Transcription Termination Factor 3 (MTERF3) negatively regulates mitochondrial gene expression and energy metabolism, and plays a significant role in many cancer types. Nevertheless, the expression and prognostic role of MTERF3 in patients with thyroid carcinoma (THCA) is still unclear. Thus, we investigated the expression, clinicopathological significance, and prognostic value of MTERF3 in THCA. Methods: The protein and mRNA expression levels of MTERF3 were, respectively, analyzed using immunohistochemistry (IHC) from THCA tissues and RNA-Seq data downloaded from The Cancer Genome Atlas. In addition, the relationships among the expression of MTERF3, the stemness feature, the extent of immune infiltration, drug sensitivity, the expression of ferroptosis, and N6-methyladenosine (m6A) methylation regulators, were evaluated as prognostic indicators for patients with THCA using the Kaplan-Meier plotter database. Results: The IHC and RNAseq results showed that the protein and mRNA expression levels of MTERF3 in adjacent nontumor tissues were significantly higher than in THCA tissues. The survival analysis indicated that decreased expression of MTERF3 was associated with a poorer prognosis. Furthermore, the expression of MTERF3 not only negatively correlated with the enhancement of the stemness of THCA and the reduction of drug sensitivity but also was implicated in ferroptosis and m6A methylation. Conclusion: The data from this study support the hypothesis that decreased expression of MTERF3 in THCA is associated with a poor prognosis.

Characterization of circRNA-Associated-ceRNA Networks Involved in the Pathogenesis of Postoperative Cognitive Dysfunction in Aging Mice.

Postoperative cognitive dysfunction (POCD) is a clinical entity associated with declined cognitive function following surgery. It occurs more frequently in elderly patients. Recent studies have shown that circRNA-associated-ceRNA networks, constructed based on interactions between circRNA-miRNA and miRNA-mRNA, provide key insight into the molecular mechanisms underlying the pathogenesis of several neurological diseases. However, the mechanism of POCD remains undetermined. In this study, laparotomies were performed under isoflurane anesthesia on young (2-month-old) and aging (17-month-old) male C57BL/6 mice. The results showed that the aging mice were more likely than the young mice to develop POCD. Subsequently, differentially expressed circRNAs, miRNAs, and mRNAs were characterized by RNA sequencing the hippocampi of young and aging mice under control and surgery conditions. Six circRNAs, 6 miRNAs, and 203 mRNAs were identified to construct the circRNA-associated-ceRNA network for the control condition, while 13 circRNAs, 8 miRNAs, and 189 mRNAs were used for the circRNA-associated-ceRNA network for the surgery condition. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of these two networks revealed that the circRNA-associated-ceRNA networks are involved in POCD pathogenesis though modulating the Wnt and VEGF signaling pathways, as well as neural processes associated with long-term synaptic depression and synaptic transmission. In particular, the mmu-miR-298-5P regulatory pathway identified in this study's mouse model suggests that mm9_circ_009789- and mm9_circ_004229-associated-ceRNA networks as closely related to the occurrence of POCD through regulating PKC signaling pathway, neural cell apoptosis and glycolipid metabolism pathway. These findings provide possible insight into the role of the circRNA-associated-ceRNA networks, helping to unravel the complexity of the molecular pathogenesis of POCD.

Dendrobium polysaccharides attenuate cognitive impairment in senescence-accelerated mouse prone 8 mice via modulation of microglial activation.

Dendrobium is one of the most important traditional Chinese medicinal foods used to treat age-related disorders. However, it remains unclear whether Dendrobium affects the progression of Alzheimer's disease (AD). In the present study, we investigated the effects of Dendrobium officinale polysaccharides (DOP) on the BV2 microglial cell line and the senescence-accelerated mouse prone 8 (SAMP8) mouse strain. In vitro experiments showed that DOP pretreatment contributed to BV2 cells shifting from proinflammatory to anti-inflammatory phenotypes with enhanced Aß clearance in response to Aß insults. For the in vivo study, mice were chronically treated with DOP in drinking water from 4 to 7 months of age. The results showed that DOP remarkably attenuated cognitive decline in SAMP8 mice. DOP also inhibited the increased hippocampal microglial activation in SAMP8 mice with downregulation of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), while interleukin-10 (IL-10), neprilysin (NEP) and insulin-degrading enzyme (IDE) were upregulated. The accumulation of hippocampal Aß42 and phosphated Tau proteins in SAMP8 mice was also reduced. Taken together, our data suggest that Dendrobium has the potential to provide neuroprotection against AD-related cognitive impairment via modulation of microglial activation.

Regulatory factor X1 depresses ApoE-dependent Aß uptake by miRNA-124 in microglial response to oxidative stress.

Decreased proteolytic clearance of soluble amyloid ß (Aß) in microglia affects Aß accumulation on Alzheimer's disease progression. However, the potential molecular mechanism by which microglial Aß uptake is regulated remains unclear. In this study, we identified a microRNA, miR-124, that was down-regulated in aging with a function in regulating apolipoprotein E (ApoE)-dependent Aß uptake by targeting regulatory factor X1 (RFX1) transcripts on BV2 microglia cell. Decreased expression of miRNA-124 in BV2 cells exposed to mild hydrogen peroxide increased RFX1 protein level and decreased the expression of ApoE, a gene which has been suggested to enhance cellular Aß uptake in microglia. We also identified a miR-124 binding site in the 3'-UTR of RFX1 mRNA and a RFX1 binding site in the first intron of ApoE gene. Furthermore, interfering this signaling pathway by knocking down RFX1 significantly improved Aß uptake in BV2 cells. These data demonstrate the mechanism through which decreased miR-124 expression under oxidative stress slowed Aß uptake and suggest that RFX1 might be a target for improving Aß clearance during aging.

Suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, attenuates postoperative cognitive dysfunction in aging mice.

Postoperative cognitive dysfunction (POCD) is a recognized clinical entity characterized with cognitive deficits after anesthesia and surgery, especially in aged patients. Previous studies have shown that histone acetylation plays a key role in hippocampal synaptic plasticity and memory formation. However, its role in POCD remains to be determined. Here, we show that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, attenuates POCD in aging Mice. After exposed to the laparotomy, a surgical procedure involving an incision into abdominal walls to examine the abdominal organs, 16- but not 3-month old male C57BL/6 mice developed obvious cognitive impairments in the test of long-term contextual fear conditioning. Intracerebroventricular (i.c.v.) injection of SAHA at the dose of (20 µg/2 µl) 3 h before and daily after the laparotomy restored the laparotomy-induced reduction of hippocampal acetyl-H3 and acetyl-H4 levels and significantly attenuated the hippocampus-dependent long-term memory (LTM) impairments in 16-month old mice. SAHA also reduced the expression of cleaved caspase-3, inducible nitric oxide synthase (iNOS) and N-methyl-D-aspartate (NMDA) receptor-calcium/calmodulin dependent kinase II (CaMKII) pathway, and increased the expression of brain-derived neurotrophic factor (BDNF), synapsin 1, and postsynaptic density 95 (PSD95). Taken together, our data suggest that the decrease of histone acetylation contributes to POCD and may serve as a target to improve the neurological outcome of POCD.

Inhibition of a novel sperm gelatinase in prawn sperm by the male reproduction-related Kazal-type peptidase inhibitor.

Previously, we have identified and characterized a male reproduction-related kazal-type peptidase inhibitor (MRPINK) gene from the prawn, Macrobrachium rosenbergii. In the present study, MRPINK was discovered to have an inhibitory effect on the gelatinolytic activity of M. rosenbergii sperm and immunofluorescence analysis revealed it bound specifically onto the base of sperm. The proteolytic activity of sperm extracts to vitelline coat components was also detected to be interfered by MRPINK. Furthermore, a novel gelatinase on sperm was found to be specifically inhibited by MRPINK and was named M. rosenbergii sperm gelatinase (MSG). MSG was then isolated and purified by reversed-phase high performance liquid chromatography combining with gelatinolytic assay. By amino-terminal amino acid sequence analysis and molecular cloning, the primary structure of MSG was determined. The data presented in this study provided evidence that MRPINK has an inhibitory effect on the gelatinolytic activity as well as proteolytic activity of prawn sperm and specifically blocks the activity of MSG.

Identification of a novel DNA methyltransferase 2 from the brine shrimp, Artemia franciscana.

DNA methyltransferase 2 (Dnmt2) is a dual-specificity DNA methyltransferase, which contains a weak DNA methyltransferase and novel tRNA methyltransferase activity. However, its biological function is still enigmatic. To elucidate the expression profiles of Dnmt2 in Artemia franciscana, we isolated the gene encoding a Dnmt2 from A. franciscana and named it as AfDnmt2. The cDNA of AfDnmt2 contained a 1140-bp open reading frame that encoded a putative Dnmt2 protein of 379 amino acids exhibiting 32% approximately 39% identities with other known Dnmt2 homologs. This is the first report of a DNA methyltransferase gene in Crustacean. By using semi-quantitative RT-PCR, AfDnmt2 was found to be expressed through all developmental stages and its expression increased during resumption of diapause cysts development. Southern blot analysis indicated the presence of multiple copies of AfDnmt2 genes in A. franciscana.

AMPK alpha subunit gene characterization in Artemia and expression during development and in response to stress.

AMP-activated protein kinase (AMPK) plays a central role in maintaining the energy balance of organisms under physiological and environmental stresses. Here two AMPK alpha subunit gene transcripts (named Afr-AMPKalpha1 and Afr-AMPKalpha2) from Artemia franciscana were isolated and gene expression was characterized by semiquantitive reverse transcription-polymerase chain reaction (RT-PCR). Afr-AMPKalpha1 was differentially expressed during Artemia developmental stages as well as in response to stresses, such as heat-shock, starvation and a hyperosmotic environment. Afr-AMPKalpha1 mRNA expression in adult Artemia decreased under heat shock, but not in a time- and temperature-dependent manner. By contrast, the transcript sharply decreased in heat-shocked cysts in a time-dependent manner. Under hyperosmotic stress, however, the mRNA level in adults first declined and then increased with prolonged exposure. In the case of starvation, the gene expression in adults decreased and was undetectable after day 9. In addition, Afr-AMPKalpha2 mRNA expression was too low to be detected without nested PCR. Southern blot analysis, moreover, indicated AMPK alpha subunit was present in multiple copies in the Artemia genome. Furthermore, our results demonstrate that the Afr-AMPKalpha1 mRNA level sharply decreases in Artemia carrying diapause-destined embryos and this indicates the possibility that Afr-AMPKalpha1 is involved in determining the reproductive mode in Artemia.

The DNA methyltransferase-2 gene in the prawn Macrobrachium rosenbergii: characteristics and expression patterns during ovarian and embryonic development.

DNA methylation plays important roles in eukaryotic development. However, studies of DNA methylation in Crustacea are very limited. In the present study, we isolated and identified a DNA methyltransferase 2 (Mar-Dnmt2) gene from the prawn Macrobrachium rosenbergii. The cDNA of Mar-Dnmt2 contained an 1,191-bp open reading frame that encoded a putative Dnmt2 protein of 396 amino acids with the ten motifs characteristic of DNA methyltransferases and exhibiting high identities with other known Dnmt2 homologs (30%-42%). By real-time PCR, an especially high level of Mar-Dnmt2 mRNA was found in the ovary, approximately 5-16 times higher than in other tissues. Moreover, Mar-Dnmt2 mRNA obviously decreased during embryonic development. On the other hand, DNA methylation was detected in this study; about 0.05% of cytosine residues were found to be methylated in the DNA of M. rosenbergii.