Hyperexcitability of neuronal networks can lead to excessive release of the excitatory neurotransmitter glutamate, which in turn can cause neuronal damage by overactivating NMDA-type glutamate receptors and related signaling pathways. This process (excitotoxicity) has been implicated in the pathogenesis of many neurological conditions, ranging from childhood epilepsies to stroke and neurodegenerative disorders such as Alzheimer’s disease (AD). Reducing neuronal levels of the microtubule-associated protein tau counteracts network hyperexcitability of diverse causes, but whether this strategy can also diminish downstream excitotoxicity is less clear.
Methods
We established a cell-based assay to quantify excitotoxicity in primary cultures of mouse hippocampal neurons and investigated the role of tau in exicitotoxicity by modulating neuronal tau expression through genetic ablation or transduction with lentiviral vectors expressing anti-tau shRNA or constructs encoding wildtype versus mutant mouse tau.
Results
We demonstrate that shRNA-mediated knockdown of tau reduces glutamate-induced, NMDA receptor-dependent Ca2+ influx and neurotoxicity in neurons from wildtype mice. Conversely, expression of wildtype mouse tau enhances Ca2+ influx and excitotoxicity in tau-deficient (Mapt−/−) neurons. Reconstituting tau expression in Mapt−/− neurons with mutant forms of tau reveals that the tau-related enhancement of Ca2+ influx and excitotoxicity depend on the phosphorylation of tau at tyrosine 18 (pY18), which is mediated by the tyrosine kinase Fyn. These effects are most evident at pathologically elevated concentrations of glutamate, do not involve GluN2B–containing NMDA receptors, and do not require binding of Fyn to tau’s major interacting PxxP motif or of tau to microtubules.
Conclusions
Although tau has been implicated in diverse neurological diseases, its most pathogenic forms remain to be defined. Our study suggests that reducing the formation or level of pY18-tau can counteract excitotoxicity by diminishing NMDA receptor-dependent Ca2+ influx.
We constructed a recombinant oral GLP-1 analogue in Lactococcus lactis (L. lactis) and evaluated its physiological functions.
Results
In silico docking suggested the alanine at position 8 substituted with serine (A8SGLP-1) reduced binding of DPP4, which translated to reduced cleavage by DPP4 with minimal changes in stability. This was further confirmed by an in vitro enzymatic assay which showed that A8SGLP-1 significantly increased half-life upon DPP4 treatment. In addition, recombinant L. lactis (LL-A8SGLP-1) demonstrated reduced fat mass with no changes in body weight, significant improvement of random glycemic control and reduced systemic inflammation compared with WT GLP-1 in db/db mice.
Conclusion
LL-A8SGLP-1 adopted in live biotherapeutic products reduce blood glucose in db/db mice without affecting its function.
Biological responses due to nutrient deprivation in the nematode Caenorhabditis elegans, including L1 diapause and autophagy during dauer formation, can be mediated through the linked DAF-2/insulin/IGF receptor and target-of-rapamycin (TOR) kinase pathways. Here we discuss how altered insulin/TOR signaling may underlie the previously reported phenotypes of worms with a null mutation in the pcm-1 gene that results in reduced autophagy during dauer formation and decreased L1 arrest survival. PCM-1 encodes a protein repair methyltransferase and mutants of the encoding pcm-1 gene are incapable of converting spontaneously damaged l-isoaspartyl residues in cellular proteins to normal forms by this pathway. We speculate that PCM-1 may function either directly or indirectly as an inhibitor of insulin/TOR signaling, perhaps in a role to balance autophagy with alternative protein degradation pathways that may be more specific for recognizing age-damaged proteins.Addendum to:The L-Isoaspartyl-O-Methyltransferase in Caenorhabditis elegans Larval Longevity and AutophagyT.A. Gomez, K.L. Banfield, D.M. Trogler and S.G. ClarkeDevelopmental Biol 2007; 303:493-500 相似文献
Interleukin-1 beta (IL-1β) is a crucial cytokine that has been implicated in cancer and metastasis development. However, its possible mechanistic role in cervical cancer remains unclear. This study aimed to investigate the functions of exogenous IL-1β in cervical cancer cell proliferation and migration.
Methods
HeLa cell proliferation and migration were measured using MTT and Transwell assays. A lentivirus-mediated packaging system was used to construct an IL-1β overexpressing cell line. MEK/ERK signal transduction was inhibited by pretreatment with the MEK inhibitor PD98059. qRT–PCR and Western blotting were used to test the expression of relevant genes.
Results
Exogenous IL-1β promoted the proliferation and migration of HeLa cells. In addition, overexpression of IL-1β in HeLa cells promoted cell proliferation. Mechanistically, exogenous IL-1β increased the phosphorylated MEK and ERK levels in HeLa cells and the expression of JUN, RELB, and NF-κB2. Alternatively, blockade of MEK inhibited the promoting proliferation effects of IL-1β and the expression of JUN, RELB, and NF-κB2.
Conclusions
Our data suggest that exogenous IL-1β regulates HeLa cell functions by regulating the MEK/ERK signaling pathway and by targeting JUN, RELB, and NF-κB2. Our study uncovered a potential association across IL-1β, cervical tumor development, and cancer progression.
Curcumin has a potent anticancer effect and is a promising new therapeutic strategy. We previously demonstrated that curcumin induced non-apoptotic autophagic cell death in malignant glioma cells in vitro and in vivo. This compound inhibited the Akt/mammalian target of rapamycin/p70 ribosomal protein S6 kinase pathway and activated the extracellular signal-regulated kinases 1/2 thereby inducing autophagy. Interestingly, activation of the first pathway inhibited curcumin-induced autophagy and cytotoxicity, whereas inhibition of the latter pathway inhibited curcumin-induced autophagy and induced apoptosis, thus augmenting the cytotoxicity of curcumin. These results imply that these two autophagic pathways have opposite effects on curcumin’s cytotoxicity. However, inhibition of nuclear factor κB, which is the main target of curcumin for its anticancer effect, was not observed in malignant glioma cells. These results suggest that autophagy but not nuclear factor κB plays a central role in curcumin anticancer therapy and warrant further investigation toward application in patients with malignant gliomas. Here, we discuss the therapeutic role of two autophagic pathways influenced by curcumin.Addendum to:Evidence That Curcumin Suppresses the Growth of Malignant Gliomas in Vitro and in Vivo through Induction of Autophagy: Role of Akt and Extracellular Signal-Regulated Kinase Signaling PathwaysH. Aoki, Y. Takada, S. Kondo, R. Sawaya, B. B. Aggarwal and Y. KondoMol Pharmacol 2007; 72:29-39 相似文献
This is an erratum to:An S/MAR-based L1 retrotransposition cassette mediates sustained levels of insertional mutagenesis without suffering from epigenetic silencing of DNA methylation DOI: 10.4161/epi.5.7.12647Danny RangasamyVolume 5, Issue 7Pages 601 - 611 相似文献
Context: Angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) play divergent roles in myocardial ischemia and reperfusion injury.Objective: To investigate serum Ang-1 and Ang-2 levels in ST-segment elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PCI).Methods: Serum Ang-1 and Ang-2 were measured in 85 STEMI patients in the first week after PCI.Results: Ang-1, Ang-2 and Ang-2/Ang-1 ratio (Ang-2/1) were all increased at admission, and had dynamic changes after PCI. Ang-2 and Ang-2/1 at admission and 2 h after PCI were positively correlated with peak cardiac troponin T levels.Conclusion: The extent of myocardial damage may be linked to circulating Ang-2 and Ang-2/1. 相似文献
Although improvement has been made in therapeutic strategies against pancreatic carcinoma, overall survival has not significantly enhanced over the past decade. Thus, the establishment of better therapeutic regimens remains a high priority.
Methods
Pancreatic cancer cell lines were incubated with romidepsin, an inhibitor of histone deacetylase, and tamoxifen, and their effects on cell growth, signaling and gene expression were analyzed. Xenografts of human pancreatic cancer CFPAC1 cells were medicated with romidepsin and tamoxifen to evaluate their effects on tumor growth.
Results
The inhibition of the growth of pancreatic cancer cells induced by romidepsin and tamoxifen was effectively reduced by N-acetyl cysteine and α-tocopherol, respectively. The combined treatment greatly induced reactive oxygen species production and mitochondrial lipid peroxidation, and these effects were prevented by N-acetyl cysteine and α-tocopherol. Tamoxifen enhanced romidepsin-induced cell senescence. FOXM1 expression was markedly downregulated in pancreatic cancer cells treated with romidepsin, and tamoxifen further reduced FOXM1 expression in cells treated with romidepsin. Siomycin A, an inhibitor of FOXM1, induced senescence in pancreatic cancer cells. Similar results were obtained in knockdown of FOXM1 expression by siRNA.
Conclusion
Since FOXM1 is used as a prognostic marker and therapeutic target for pancreatic cancer, a combination of the clinically available drugs romidepsin and tamoxifen might be considered for the treatment of patients with pancreatic cancer.
It has been widely reported that long non-coding RNAs (lncRNAs) could affect the varieties of tumor response to radiotherapy. LncRNA HNF1A-AS1 is transcribed from HNF1A gene cluster’s antisense strand. This work focused on the mechanism of how HNF1A-AS1 participated in the radiosensitivity of non-small cell lung cancer (NSCLC).
Methods
The mRNA or protein expression of HNF1A-AS1, miR-92a-3p MAP2K4, and JNK in NSCLC cells and tissues was detected by qRT-PCR or western blotting. RNA immunoprecipitation (RIP) detection and luciferase reporting system were used to evaluate the relationship between HNFA-AS1 and miR-92a-3p or between miR-92a-3p and MAP2K4. Flow cytometry assays, colony formation, and MTT were performed to analyze the function changes in A549 and Calu-1 cells. The rescue experiment was also conducted to explore the underlying mechanisms.
Results
HNF1A-AS1 was investigated in NSCLC cells and tissues and highly related to the advanced pathological stage. HNF1A-AS1 bound with miR-92a-3p, which was downregulated in NSCLC. It showed that miR-92a-3p was negatively related to HNF1A-AS1. Knockdown of HNF1A-AS1 impacted most cell biological behaviors in NSCLC cells, including restricting the proliferation and aggravating apoptosis. Furthermore, knockdown of HNF1A-AS1 dramatically enhanced radiotherapy sensitivity of NSCLC. Moreover, miR-92a-3p was found to target MAP2K4 and could reduce MAP2K4 expression. Inhibition of HNF1A-AS1 elevated radiotherapy sensitivity and retarded the progression of NSCLC cells, followed by decreasing expression levels of MAP2K4. Besides, MAP2K4 mimic rescued the si-HNF1A-AS1 effects on the biological behavior of NSCLC cells.
Conclusion
HNF1A-AS1 is highly expressed in NSCLC. MiR-92a-3p is the target gene of HNF1A-AS1 and involved in tumor progression by regulating the MAP2K4/JNK pathway. HNF1AS1/miR-92a-3p/MAP2K4 axis plays important roles in radiotherapy resistance of NSCLC.
ABSTRACTAims: The analysis of the online databases revealed that CCND1 expression is correlated with poor prognosis in LSCC. We aimed to explore the function of CCND1 in tumor progression in LSCC.Main methods: The expression of mRNA was measured using qRT-PCR. Protein expression was assessed by Western blot. Cell migration and invasion were assessed by transwell assay.Key findings: CCND1 was co-overexpressed with FGFR1 in lung cancer patients. Overexpression of CCND1 promoted LSCC cell proliferation and metastasis. FGFR1 promoted the processes of EMT through AKT/MAPK signaling by targeting CCND1 in FGFR1-amplification cell lines.Significance: IIn conclusion, our study demonstrated the regulatory mechanism between CCND1 and FGFR1 in FGFR1 amplified LSCC. Co-targeting CCND1 and FGFR1 could provide greater clinical benefits. 相似文献
Loss of autophagy causes liver injury, cardiomyopathy, and neurodegeneration, associated with the formation of ubiquitin-positive inclusion bodies. However, the pathogenic mechanism and molecular machinery involved in inclusion formation are not fully understood. We recently identified a ubiquitin-binding protein, p62/A170/SQSTM1, as a molecule involved in inclusion formation. p62 interacts with LC3 which regulates autophagosome formation, through an 11 amino acid sequence rich in acidic and hydrophobic residues, named the LC3-recognition sequence (LRS), and the LC3-p62 complex is degraded by autophagy. Furthermore, structural analysis reveals an interaction of Trp-340 and Leu-343 of p62 with different hydrophobic pockets in the ubiquitin-fold of LC3. p62 mutants, defective in binding the LRS, escape efficient turnover by autophagy, forming ubiquitin- and p62-positive inclusions. Importantly, such ubiquitin- and p62-positive inclusions are identified in various human diseases, implying the involvement of autophagy in their pathogenic mechanisms. Our reports identify an important role for autophagy in the selective turnover of p62, and demonstrate that in addition to the essential role of LC3 in autophagosome formation, LC3 is also involved in sorting autophagy-specific substrate(s).Addendum to: Komatsu M, Waguri S, Koike M, Sou YS, Ueno T, Hara T, Mizushima N, Iwata JI, Ezaki J, Murata S, Hamazaki J, Nishito Y, Iemura SI, Natsume T, Yanagawa T, Uwayama J, Warabi E, Yoshida H, Ishii T, Kobayashi A, Yamamoto M, Yue Z, Uchiyama Y, Kominami E, Tanaka K. Homeostatic levels of p62 control cytoplasmic inclusion body formation in autophagy-deficient mice. Cell 2007; 131:1149-63.andIchimura Y, Kumanomidou T, Sou YS, Mizushima T, Ezaki J, Ueno T, Kominami E, Yamane T, Tanaka K, Komatsu M. Structural basis for sorting mechanism of p62 in selective autophagy. J Biol Chem 2008; 283:22847-57. 相似文献
Anti-PD-1/PD-L1-based therapy has emerged recently, and we aimed to figure out the latent value of different clinical and molecular factors to predict the efficacy of immune checkpoint inhibitors (ICIs) therapy compared with non-immunotherapy in the first-line setting. 相似文献
Objective: This study investigated whether the extracellular signal-regulated kinase 1/2 (ERK1/2) signal pathway affects cardiomyocyte apoptosis and the expression of tumor necrosis factor (TNF-α) at different glucose-lowering rates.Methods: Cardiomyocytes of Wistar neonate rats were maintained in a medium supplemented with 25?mmol/L glucosamine for 72?h. Then the medium was changed to different concentrations of glucosamine, and all cells were divided into five groups. The survival rate of cardiomyocyte was measured using the Cell Counting Kit-8; cardiomyocyte apoptosis was measured using the flow cytometry instrument and laser confocal microscope; TNF-α was measured using the enzyme-linked immunosorbent assay; and ERK1/2 protein and phosphorylation were measured using the Western blot. Cardiomyocyte apoptosis and TNF-α were measured again after adding U0126.Results: As the glucose-lowering rate increased, the survival rate of cardiomyocytes increased in group B and decreased in groups C, D, and E. The TNF-α concentration increased in groups B, C, and D and decreased in group E. After 24?h, the apoptosis rate decreased in group B and increased in groups C, D, and E. The expression of p-ERK1/2 increased in groups B, D, and E, and was the lowest in group C. After adding U0126, the survival rate of cardiomyocyte in all groups increased and TNF-α concentration decreased.Conclusions: The influence of glucose-lowering rate on cardiomyocyte apoptosis and TNF-α was caused by the p-ERK1/2 pathway. During the glucose-lowering course, the p-ERK1/2 pathway promoted cardiomyocyte apoptosis, and TNF-α secretion was related to not only osmotic pressure but also ERK1/2 signal pathway activation. 相似文献
