Sevoflurane-Induced Neurotoxicity in the Developing Hippocampus via HIPK2/AKT/mTOR Signaling.

Sevoflurane (Sev) is a widely used inhalational anesthetic for general anesthesia in children. Previous studies have confirmed that multiple exposures to inhaled anesthetic can induce long-term neurotoxicity in newborn mice. However, the underlying mechanisms remain elusive. In this study, we investigated the role of homeodomain interacting protein kinase 2 (HIPK2), a stress activating kinase involved in neural survival and synaptic plasticity, and its underlying mechanism in sevoflurane-induced neurotoxicity. Empirical study showed that neuronal apoptosis was elevated after exposure to sevoflurane. Meanwhile, up-regulation of HIPK2 and AKT/mTOR signaling was observed in primary hippocampal neurons and hippocampus in mice upon anesthetic exposure. A64, antagonist of HIPK2, could significantly reduce increased apoptosis and activation of AKT/mTOR induced by sevoflurane. AKT antagonist MK2206 partially alleviated neuronal apoptosis without affecting the expression of HIPK2. Experimental results demonstrated a crucial role of HIPK2/AKT/mTOR signaling in neurotoxicity of sevoflurane. Thus, HIPK2/AKT/mTOR signaling can serve as a potential target for the protection of inhalation anesthesia-induced cytotoxicity in the future.

A systematic review on active sites and functions of PIM-1 protein.

The Proviral Integration of Molony murine leukemia virus (PIM)-1 protein contributes to the solid cancers and hematologic malignancies, cell growth, proliferation, differentiation, migration, and other life activities. Many studies have related these functions to its molecular structure, subcellular localization and expression level. However, recognition of specific active sites and their effects on the activity of this constitutively active kinase is still a challenge. Based on the close relationship between its molecular structure and functional activity, this review covers the specific residues involved in the binding of ATP and different substrates in its catalytic domain. This review then elaborates on the relevant changes in protein conformation and cell functions after PIM-1 binds to different substrates. Therefore, this intensive study can improve the understanding of PIM-1-regulated signaling pathways by facilitating the discovery of its potential phosphorylation substrates.

Doxorubicin-induced toxicity to 3D-cultured rat ovarian follicles on a microfluidic chip.

Doxorubicin (DOX) has dose-dependent toxicity on ovarian follicles (OFs), and the inhibition of different signaling molecules along with the DOX application for enhancing its efficacy can also upsurge this toxicity. Therefore, it is strongly required to explore the mechanism of DOX-induced toxicity in 3D culture systems for protecting the OFs. A microfluidic chip was used to culture a single OF to identify the potential signaling molecules and their combined effects on OFs dynamically. The chip offers better 3D biomimetic microenvironment to the growing OF than 2D culture systems. The OFs cultured on the chip were treated with DOX and the inhibitors of Src, Ca2+, and PIM. Their mutual effects were studied on OFs growth and 17ß-estradiol secretion. Besides, the RNA levels of B4GALT2 and UNC5C genes of DOX-exposed OFs were detected by RT-qPCR, and TUNEL staining experiments were conducted to check the OF apoptosis. The results showed that DOX application reduced the OFs growth and hormone secretion and induced apoptosis in the OFs. Moreover, the DOX-induced toxic effects were enriched by Src and PIM inhibition, while reduced by the ER-Ca2+ channel inhibitor. This study specifically demonstrates the synergistic effects of some signaling molecules on DOX-mediated cellular functions of OFs and demands some meditative measures to decipher this toxicity for supporting the female endocrine and reproductive functions.

Induction of apoptosis by Bigelovii A through inhibition of NF­κB activity.

Bigelovii A is a 30­nortriterpenoid glycoside, isolated from Salicornia bigelovii Torr. Until now, the effect of Bigelovii A on breast cancer treatment was unknown. The present research indicated that Bigelovii A significantly inhibited the proliferation of human breast cancer cells (MCF­7, MDA­MB­231 and MDA­MB­468) in a concentration­dependent manner. It was particularly effective in MCF7 cells, with an IC50 value of 4.10±1.19 µM. The anti­proliferative effect of Bigelovii A was ascribed to the induction of apoptosis, which was characterized by chromatin condensation, externalization of phosphatidylserine on the plasma membrane, hypodiploid DNA, activation of caspases and poly (ADP­ribose) polymerase cleavage. Furthermore, Bigelovii A reduced B-cell lymphoma 2 (Bcl­2) and B­cell lymphoma­extra large (Bcl­xl) expression and caused disruption of mitochondrial membrane potential, which are indicative features of mitochondria­dependent apoptotic signals. It was also identified that Bigelovii A downregulated the constitutive activation of nuclear factor (NF)­κB, as indicated by the electrophoretic mobility gel shift assay and immunocytochemistry. Furthermore, Bigelovii A suppressed constitutive IκBα phosphorylation via inhibition of IκB kinase activity. In addition to the effects on Bcl­2 and Bcl­xl, Bigelovii A also downregulated the expression of the NF­κB­regulated gene products, Cyclin D1 and cyclooxygenase­2. This led to the induction of apoptosis and arrest of cells at the G1 phase of the cell cycle.

RIPK3/MLKL-Mediated Neuronal Necroptosis Modulates the M1/M2 Polarization of Microglia/Macrophages in the Ischemic Cortex.

Cell death and subsequent inflammation are 2 key pathological changes occurring in cerebral ischemia. Active microglia/macrophages play a double-edged role depending on the balance of their M1/M2 phenotypes. Necrosis is the predominant type of cell death following ischemia. However, how necrotic cells modulate the M1/M2 polarization of microglia/macrophages remains poorly investigated. Here, we reported that ischemia induces a rapid RIPK3/MLKL-mediated neuron-dominated necroptosis, a type of programmed necrosis. Ablating RIPK3 or MLKL could switch the activation of microglia/macrophages from M1 to the M2 type in the ischemic cortex. Conditioned medium of oxygen-glucose deprivation (OGD)-treated wild-type (WT) neurons induced M1 polarization, while that of RIPK3-/- neurons favored M2 polarization. OGD treatment induces proinflammatory IL-18 and TNFα in WT but not in RIPK3-/- neurons, which in turn upregulate anti-inflammatory IL-4 and IL-10. Furthermore, the expression of Myd88-a common downstream adaptor of toll-like receptors-is significantly upregulated in the microglia/macrophages of ischemic WT but not of RIPK3-/- or MLKL-/- cortices. Antagonizing the function of Myd88 could phenocopy the effects of RIPK3/MLKL-knockout on the polarization of microglia/macrophages and was neuroprotective. Our data revealed a novel role of necroptotic neurons in modulating the M1/M2 balance of microglia/macrophages in the ischemic cortex, possibly through Myd88 signaling.

Isolation, identification and cytotoxicity of a new noroleanane-type triterpene saponin from Salicornia bigelovii Torr.

Salicornia bigelovii Torr. has been consumed not only as a popular kind of vegetable, but also as a medicinal plant to treat hypertension, cephalalgia, scurvy and cancer. The present study was designed to investigate its chemical components and cytotoxic activity. A new noroleanane-type triterpene saponin, bigelovii C (1), was separated and purified from Salicornia bigelovii Torr., along with four known triterpene saponins 2-5. The structure of bigelovii C was elucidated as 3-O-(6-O-butyl ester)-ß-D-glucuropyranosyl-23-aldehyde-30-norolean-12, 20 (29)-dien-28-oic acid-28-O-ß-D-glucopyranoside, according to various spectroscopic analysis and chemical characteristics. Besides Compounds 3 and 5, bigelovii C had potent cytotoxicity against three human cancer cell lines, MCF7 (breast cancer), Lovo (colon cancer) and LN229 (glioblastoma), especially MCF7. Bigelovii C inhibited the growth of MCF7 cells in dose- and time-dependent manners. Flow cytometry analysis revealed that the percentage of apoptotic cells significantly increased upon bigelovii C treatment. Rh123 staining assay indicated that bigelovii C reduced the mitochondrial membrane potential. The mechanism of cell death by bigelovii C may be attributed to the downregulation of Bcl-2 and upregulation of Bax, cleaved caspase-9, caspase-7 and PARP. These results suggested that bigelovii C may impart health benefits when consumed and should be regarded as a potential chemopreventative agent for cancer.

Bigelovii A induces apoptosis of HL­60 human acute promyelocytic leukaemia cells.

In the present study, the antitumor effects of the nor­Oleanane type triterpene saponin, Bigelovii A, isolated from Salicornia bigelovii Torr, were examined. Bigelovii A was demonstrated to inhibit HL­60 human acute promyelocytic leukaemia cell growth with an IC50 value of 2.15 µg/ml. In addition, Bigelovii A promoted apoptosis in HL­60 cells, as shown by apoptotic morphological changes and the hypodiploid cell assay. Apoptotic induction by Bigelovii A was associated with the downregulation of Bcl­2, the upregulation of Bax and the activation of caspase­3, as demonstrated by RT­PCR and western blot analysis. In addition, a lactate dehydrogenase release test indicated that Bigelovii A may exhibit cytotoxic activity by the induction of cell membrane impairment. This study is the first to identify that Bigelovii A exhibits potential antitumor activity and induces marked apoptosis and membrane permeabilisation in HL­60 cells. Bigelovii A may be a novel candidate for future cancer therapy.