Molecular Mechanism of Biofilm Locator Protein Kinase Dbf2p-related kinase 1 in Regulating Innate Immune Response to Interleukin 17-induced Viral Pneumonia.

It focused on the antiviral immune regulation of biofilm-localized protein kinase Dbf2p-related kinase 1 (NDR1) in viral pneumonia. Mouse alveolar monocyte RAW264.7 was used as blank control, and viral pneumonia cell model was prepared by infecting cells with respiratory syncytial virus (RSV). NDR1 overexpression vector and siRNA interference sequences were synthesized, and overexpression/silence NDR1 cell model was fabricated. About 50 ng/mL interleukin 17 (IL-17) was given to stimulate. Enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcription PCR (RT-qRCR), and Western blot were performed to detect cytokines and chemokines, mRNA of inflammatory factors, and signal molecule protein expression. Notably, RSV infection increased RSV-F mRNA in RAW264.7 cells and reduced NDR1 mRNA and protein. Secretion levels of IL-6, interferon ß (IFN-ß), chemokine (C-X-C motif) ligand 2 (CXCL2), and chemokine (C-C motif) ligand 2 (CCL20) increased in the model group versus blank control (P< 0.05). IL-6, IFN-ß, tumor necrosis factor α (TNF-α), and toll-like receptor 3 (TLR3) mRNA were up-regulated (P < 0.05). Extracellular signal-regulated kinase (ERK1/2), p38 protein phosphorylation, human recombinant 1 (TBK1), and nuclear factor kappa-B (NF-κB) protein levels increased (P < 0.05). After overexpression of NDR1, the secretion levels of cytokines and chemokines, inflammatory factors mRNA, and signal molecule protein increased significantly. After NDR1 was silenced, cytokines and chemokines, inflammatory factors mRNA, and signal molecule protein were not significantly different versus blank control group (P > 0.05). In short, NDR1 regulated innate immune response to viral pneumonia induced by IL-17, which can be used as a new target for the treatment of IL-17-induced inflammatory response and autoimmune diseases.

Metformin restores hippocampal neurogenesis and learning and memory via regulating gut microbiota in the obese mouse model.

Numerous studies have shown that over-nutritional obesity may lead to pre-diabetes, type 2 diabetes and cognitive decline. As the degree of metabolic disorders increases, the cognitive decline is getting worse. However, the cellular events that cause this cognitive dysfunction is yet to be clarified. We used a high-fat diet (HFD) consumption-induced obesity mouse model to test the effects of metformin on the hippocampal neurogenesis and learning and memory abilities of obese mice. 5-Bromo-2'-deoxyuridine (BrdU) labelling and retrovirus labeling were applied to detect hippocampal newborn neurons. Behavioral experiments were used to detect learning and memory abilities of mice. 16S rRNA gene sequencing was performed to detect the composition of gut microbiota. The positron emission tomography (PET) was conducted to detect the energy metabolism activity of different mouse brain regions. Our results reveal that metformin restores the impairment of neurogenesis in the dentate gyrus and finally prevents the cognitive decline of the obese mice. Moreover, the therapeutic effects of metformin are achieved by regulating the composition of gut microbiota of mice, which may inhibit microglia activation and neuroinflammation in the brain of obese mice. This study suggests that metformin may be taken as a promising candidate for the intervention of cognitive decline related to imbalance of gut microbiota caused by obesity.

Neuron-Specific Apolipoprotein E4 (1-272) Fragment Induces Tau Hyperphosphorylation and Axonopathy via Triggering Endoplasmic Reticulum Stress.

Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD). It is shown that apoE4 preferentially undergoes aberrant cleavage in neurons, yielding neurotoxic C-terminal-truncated apoE4 fragment. Endoplasmic reticulum (ER) stress has also been known to be involved in the pathogenesis of AD. However, little is known about the contribution of ER stress to the neurotoxicity of apoE4 fragment. In the present study, we established the neuron-specific expression human C-terminal-truncated apoE4(1-272) fragment transgenic mice and also transfected apoE4(1-272) fragment in neuroblastoma N2a cells. We found that human apoE4(1-272) fragment could trigger ER stress as evidenced by increasing the expression of ER stress markers both in vivo and in vitro. Meanwhile, the apoE4(1-272) transgenic mice presented obviously AD-like neuropathological changes, including the impairment of spatial learning and memory, prominent axonal morphological changes, and hyperphosphorylation of tau. At the same time, we also found that glycogen synthase kinase-3 activities were significantly increased. Furthermore, these neuropathological changes, especially tau hyperphosphorylation and axonal transport impairment, were significantly rescued by the ER stress protector 4-phenylbutyric acid (4-PBA) in apoE4(1-272)-transfected N2a cells. Pretreatment with 4-PBA not only decreased the protein expression of immunoglobulin binding protein (BiP) and C/EBP-homologous protein (CHOP), but also significantly reversed these defects in axonal transport. These results suggested that the neurotoxic effects of apoE4(1-272) fragment found in AD subjects, at least in part, through triggering ER stress and inducing tau hyperphosphorylation, led to the enduring impairment of axonal transport.

Melatonin Mediates Protective Effects against Kainic Acid-Induced Neuronal Death through Safeguarding ER Stress and Mitochondrial Disturbance.

Kainic acid (KA)-induced neuronal death is linked to mitochondrial dysfunction and ER stress. Melatonin is known to protect hippocampal neurons from KA-induced apoptosis, but the exact mechanisms underlying melatonin protective effects against neuronal mitochondria disorder and ER stress remain uncertain. In this study, we investigated the sheltering roles of melatonin during KA-induced apoptosis by focusing on mitochondrial dysfunction and ER stress mediated signal pathways. KA causes mitochondrial dynamic disorder and dysfunction through calpain activation, leading to neuronal apoptosis. Ca2+ chelator BAPTA-AM and calpain inhibitor calpeptin can significantly restore mitochondrial morphology and function. ER stress can also be induced by KA treatment. ER stress inhibitor 4-phenylbutyric acid (PBA) attenuates ER stress-mediated apoptosis and mitochondrial disorder. It is worth noting that calpain activation was also inhibited under PBA administration. Thus, we concluded that melatonin effectively inhibits KA-induced calpain upregulation/activation and mitochondrial deterioration by alleviating Ca2+ overload and ER stress.