Glutamine increases stability of TPH1 mRNA via p38 mitogen-activated kinase in mouse mastocytoma cells.

Expression changes for tryptophan hydroxylase 1 (TPH1), the rate-limiting enzyme in serotonin synthesis, by environmental glutamine (GLN) were examined in mouse mastocytoma-derived P815-HTR cells. GLN-treated cells exhibited a robust increase in TPH1 mRNA after a 6 h exposure to GLN. 6-Diazo-5-oxo-L-norleucine (DON), a glutamine-utilizing glutaminase inhibitor, significantly inhibited the GLN-induction of TPH1 mRNA. Nuclear run-on assays and mRNA decay experiments demonstrated that the primary mechanism leading to increased TPH1 mRNA levels was not due to transcriptional changes, but rather due to increased TPH1 RNA stability induced by GLN. Treatment with GLN also led to activation of p38 MAP kinase, but not p42/44 MAPK. In addition, SB203580, a p38 MAP kinase specific inhibitor, completely abolished the GLN-mediated increase of TPH1 mRNA levels, suggesting the pathway stabilizing TPH1 mRNA might be mediated by the activated p38 MAP kinase pathway. Additionally, SB203580 significantly reduced the stability of TPH1 mRNA, and this reduction of the stability was not affected by GLN in the culture medium, implying a sequential signaling from GLN being mediated by p38 MAP kinase, resulting in alteration of TPH1 mRNA stability. TPH1 mRNA stability loss was also dependent on de novo protein synthesis as shown by treatment of cells with a transcriptional/translational blocker. We provide evidence that TPH1 mRNA levels are increased in response to increased exogenous GLN in mouse mastocytoma cells via a stabilization of TPH1 mRNA due to the activity of the p38 MAP kinase.

Src-mediated phosphorylation of ßPix-b regulates dendritic spine morphogenesis.

PAK-interacting guanine nucleotide exchange factor (ßPix; also known as Arhgef7) has been implicated in many actin-based cellular processes, including spine morphogenesis in neurons. However, the molecular mechanisms by which ßPix controls spine morphology remain elusive. Previously, we have reported the expression of several alternative spliced ßPix isoforms in the brain. Here, we report a novel finding that the b isoform of ßPix (ßPix-b) mediates the regulation of spine and synapse formation. We found that ßPix-b, which is mainly expressed in neurons, enhances spine and synapse formation through preferential localization at spines. In neurons, glutamate treatment efficiently stimulates Rac1 GEF activity of ßPix-b. The glutamate stimulation also promotes Src-mediated phosphorylation of ßPix-b in both an AMPA receptor- and NMDA receptor-dependent manner. Tyrosine 598 (Y598) of ßPix-b is identified as the major Src-mediated phosphorylation site. Finally, Y598 phosphorylation of ßPix-b enhances its Rac1 GEF activity that is critical for spine and synapse formation. In conclusion, we provide a novel mechanism by which ßPix-b regulates activity-dependent spinogenesis and synaptogenesis via Src-mediated phosphorylation.

Azoxystrobin Impairs Neuronal Migration and Induces ROS Dependent Apoptosis in Cortical Neurons.

Fungicides often cause genotoxic stress and neurodevelopmental disorders such as autism (ASD). Fungicide-azoxystrobin (AZOX) showed acute and chronic toxicity to various organisms, and remained a concern for ill effects in developing neurons. We evaluated the neurotoxicity of AZOX in developing mouse brains, and observed prenatal exposure to AZOX reduced neuronal viability, neurite outgrowth, and cortical migration process in developing brains. The 50% inhibitory concentration (IC50) of AZOX for acute (24 h) and chronic (7 days) exposures were 30 and 10 µM, respectively. Loss in viability was due to the accumulation of reactive oxygen species (ROS), and inhibited neurite outgrowth was due to the deactivation of mTORC1 kinase activity. Pretreatment with ROS scavenger- N-acetylcysteine (NAC) reserved the viability loss and forced activation of mTORC1 kinase revived the neurite outgrowth in AZOX treated neurons. Intra-amniotic injection of AZOX coupled with in utero electroporation of GFP-labelled plasmid in E15.5 mouse was performed and 20 mg/kg AZOX inhibited radial neuronal migration. Moreover, the accumulation of mitochondria was significantly reduced in AZOX treated primary neurons, indicative of mitochondrial deactivation and induction of apoptosis, which was quantified by Bcl2/Bax ratio and caspase 3 cleavage assay. This study elucidated the neurotoxicity of AZOX and explained the possible cure from it.

Targeting the Difficult-to-Drug CD71 and MYCN with Gambogic Acid and Vorinostat in a Class of Neuroblastomas.

BACKGROUND/AIMS: Although neuroblastoma is a heterogeneous cancer, a substantial portion overexpresses CD71 (transferrin receptor 1) and MYCN. This study provides a mechanistically driven rationale for a combination therapy targeting neuroblastomas that doubly overexpress or have amplified CD71 and MYCN. For this subset, CD71 was targeted by its natural ligand, gambogic acid (GA), and MYCN was targeted with an HDAC inhibitor, vorinostat. A combination of GA and vorinostat was then tested for efficacy in cancer and non-cancer cells. METHODS: Microarray analysis of cohorts of neuroblastoma patients indicated a subset of neuroblastomas overexpressing both CD71 and MYCN. The viability with proliferation changes were measured by MTT and colony formation assays in neuroblastoma cells. Transfection with CD71 or MYCN along with quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were used to detect expression changes. For pathway analysis, gene ontology (GO) and Protein-protein interaction analyses were performed to evaluate the potential mechanisms of GA and vorinostat in treated cells. RESULTS: For both GA and vorinostat, their pathways were explored for specificity and dependence on their targets for efficacy. For GA-treated cells, the viability/proliferation loss due to GA was dependent on the expression of CD71 and involved activation of caspase-3 and degradation of EGFR. It relied on the JNK-IRE1-mTORC1 pathway. The drug vorinostat also reduced cell viability/proliferation in the treated cells and this was dependent on the presence of MYCN as MYCN siRNA transfection led to a blunting of vorinostat efficacy and conversely, MYCN overexpression improved the vorinostat potency in those cells. Vorinostat inhibition of MYCN led to an increase of the pro-apoptotic miR183 levels and this, in turn, reduced the viability/proliferation of these cells. The combination treatment with GA and vorinostat synergistically reduced cell survival in the MYCN and CD71 overexpressing tumor cells. The same treatment had no effect or minimal effect on HEK293 and HEF cells used as models of non-cancer cells. CONCLUSION: A combination therapy with GA and vorinostat may be suitable for MYCN and CD71 overexpressing neuroblastomas.

Oxyresveratrol activates parallel apoptotic and autophagic cell death pathways in neuroblastoma cells.

BACKGROUND: Drug resistance from apoptosis is a challenging issue with different cancer types, and there is an interest in identifying other means of inducing cytotoxicity. Here, treatment of neuroblastoma cells with oxyresveratrol (OXYRES), a natural antioxidant, led to dose-dependent cell death and increased autophagic flux along with activation of caspase-dependent apoptosis. METHODS: For cell viability, we performed the CCK-8 assay. Protein expression changes were with Western blot and immunocytochemistry. Silencing of proteins was with siRNA. The readouts for cell cycle, mitochondria membrane potential, caspase-3, autophagy and apoptosis were performed with flow cytometry. RESULTS: Phosphorylation of p38 MAPK increased with OXYRES treatment and inhibition of p38 reduced autophagy and cell death from OXYRES. In contrast, PI3K/AKT/mTOR signaling decreased in the target cells with OXYRES and inhibition of PI3K or mTOR enhanced OXYRES-mediated cytotoxicity with increased levels of autophagy. Modulation of either of the apoptosis and autophagy flux pathways affected the extent of cell death by OXYRES, but did not affect the indicators of these pathways with respect to each other. Both pathways were independent of ROS generation or p53 activation. CONCLUSION: OXYRES led to cell death from autophagy, which was independent of apoptosis induction. The OXYRES effects were due to changes in the activity levels of p38 MAPK and PI3K/AKT/mTOR. GENERAL SIGNIFICANCE: With two independent and parallel pathways for cytotoxicity induction in target cells, this study puts forward a potential utility for OXYRES or the pathways it represents as novel means of inducing cell death in neuroblastoma cells.

Lys1110 of TRPM2 is critical for channel activation.

TRPM2 (transient receptor potential melastatin 2) is a non-selective Ca2+-permeable cation channel activated by ADPR (adenosine diphosphoribose) and H2O2. It is widely expressed in mammalian cells and plays an important role in the regulation of various cell functions. However, the mechanisms of TRPM2 channel activation are not fully understood. Previously, we reported that TRPM2 channel activation is induced by high intracellular Cl- concentration. In the present study, we investigated the functional role of Lys1110 in the membrane-proximal C-terminal region by site-directed mutagenesis. Replacement of the positively charged amino acid lysine (Lys1110) with the neutrally charged amino acid asparagine (K1110N) or the negatively charged amino acid glutamic acid (K1110E) generated mutants that failed to induce an increase in free cytosolic calcium concentration ([Ca2+]i) not only by intracellular injection of Cl-, but also by H2O2 or ADPR. However, a mutant generated by replacing the lysine residue with a positively charged amino acid arginine (K1110R) displayed channel activity similar to wild-type TRPM2. Interestingly, in the K1107N/K1110N double-point mutant, the impaired function of the K1110N mutant in response to ADPR and H2O2, but not to Cl-, was recovered. There were no changes in protein expression, membrane trafficking and oligomerization of the mutant channels. The extent of [Ca2+]i increase by H2O2 in HEK (human embryonic kidney)-293 cells expressing TRPM2 mutants was well correlated with the degree of susceptibility to H2O2-induced cell death. These results display the crucial role of a positively charged amino acid residue at position 1110 for TRPM2 channel activity.

Cytotoxic effect of gambogic acid on SH-SY5Y neuroblastoma cells is mediated by intrinsic caspase-dependent signaling pathway.

Gambogic acid (GA) is the dry resin of Garcinia hanburyi (Guttiferae) with potent anti-tumor activity, various bioactivities, including detoxification, homeostasis, anti-inflammatory, and parasiticide, whereas the effect of this natural compound on cancer cells has not been clearly clarified. Here, we examined cellular cytotoxicity by cell viability assay and DNA fragmentation by DNA-ladder assay. Activation of different protein expressions were detected by western blot analyses. We first demonstrated that GA reduces the human SH-SY5Y neuroblastoma cell viability with IC50 of 1.28 µM at 6 h which has less toxicity in fibroblast cells. However, lower concentration GA significantly downregulated the expression of anti-apoptotic protein including Bcl-2, Bcl-xL, and Mcl-1, which also dramatically activated cleaved caspase-9 and -3 in a dose- and time-dependent manner. Consequently, GA-induced cytotoxicity was not mediated by the Fas/FasL and PI3 K/AKT/GSK-3ß signaling pathway. In addition, GA-induced cells showed damage morphology which had become cell rounding, neurite retraction, membrane blebbing and shrunken in a dose- and time-dependent manner that clearly indicates this morphological change might be due to the process of apoptosis which shows fragmented DNA. Therefore, the findings presented in this study demonstrate that apoptotic effects of GA on SH-SY5Y cells are mediated by intrinsic mitochondrion-dependent caspase pathway which suggests this natural compound might be effective as an anti-cancer agent for neuroblastoma malignancies.

Impact of the circadian nuclear receptor REV-ERBα in dorsal raphe 5-HT neurons on social interaction behavior, especially social preference.

Social interaction among conspecifics is essential for maintaining adaptive, cooperative, and social behaviors, along with survival among mammals. The 5-hydroxytryptamine (5-HT) neuronal system is an important neurotransmitter system for regulating social behaviors; however, the circadian role of 5-HT in social interaction behaviors is unclear. To investigate whether the circadian nuclear receptor REV-ERBα, a transcriptional repressor of the rate-limiting enzyme tryptophan hydroxylase 2 (Tph2) gene in 5-HT biosynthesis, may affect social interaction behaviors, we generated a conditional knockout (cKO) mouse by targeting Rev-Erbα in dorsal raphe (DR) 5-HT neurons (5-HTDR-specific REV-ERBα cKO) using the CRISPR/Cas9 gene editing system and assayed social behaviors, including social preference and social recognition, with a three-chamber social interaction test at two circadian time (CT) points, i.e., at dawn (CT00) and dusk (CT12). The genetic ablation of Rev-Erbα in DR 5-HTergic neurons caused impaired social interaction behaviors, particularly social preference but not social recognition, with no difference between the two CT points. This deficit of social preference induced by Rev-Erbα in 5-HTDR-specific mice is functionally associated with real-time elevated neuron activity and 5-HT levels at dusk, as determined by fiber-photometry imaging sensors. Moreover, optogenetic inhibition of DR to nucleus accumbens (NAc) 5-HTergic circuit restored the impairment of social preference in 5-HTDR-specific REV-ERBα cKO mice. These results suggest the significance of the circadian regulation of 5-HT levels by REV-ERBα in regulating social interaction behaviors.

Angelicin induces apoptosis through intrinsic caspase-dependent pathway in human SH-SY5Y neuroblastoma cells.

Angelicin is structurally related to psoralens, a well-known chemical class of photosensitizers used for its antiproliferative activity in treatment of different skin diseases. To verify the activity of angelicin, we employed human SH-SY5Y neuroblastoma cells to investigate its cytotoxicity, although its mechanism of action has not yet been fully elucidated. Here, we examined the cellular cytotoxicity of angelicin by cell viability assay, DNA fragmentation by DNA ladder assay, and activation of caspases and Bcl-2 family proteins by western blot analyses. The results of our investigation suggest that angelicin increased cellular cytotoxicity in a dose- and time-dependent manner with IC(50) of 49.56 µM at 48 h of incubation. In addition, angelicin dose-dependently downregulated the expression of anti-apoptotic proteins including Bcl-2, Bcl-xL, and Mcl-1 suggesting the involvement of the intrinsic mitochondria-mediated apoptotic pathway which did not participate in Fas/FasL-induced caspase-8-mediated extrinsic, MAP kinases, and PI3K/AKT/GSK-3ß pathway. Furthermore, we clarified the dose-dependent upregulation of caspase-9 and caspase-3 which indicated that angelicin-induced apoptosis is mediated primarily through the intrinsic caspase-mediated pathway. In particular, the caspase-3 inhibitor, DEVD-fmk, induced a reduction in angelicin-induced cytotoxicity which confirmed that the intrinsic caspase-dependent pathway during this apoptosis which did not prevent cytotoxicity using MAP kinases and GSK-3 inhibitor. Taken together, our data shows that angelicin is an effective apoptosis-inducing natural compound of human SH-SY5Y neuroblastoma cells which suggests that this compound may have a role in future therapies for human neuroblastoma cancer.

RNA Binding Protein Rbms1 Enables Neuronal Differentiation and Radial Migration during Neocortical Development by Binding and Stabilizing the RNA Message for Efr3a.

Various RNA-binding proteins (RBPs) are key components in RNA metabolism and contribute to several neurodevelop-mental disorders. To date, only a few of such RBPs have been characterized for their roles in neocortex development. Here, we show that the RBP, Rbms1, is required for radial migration, polarization and differentiation of neuronal progenitors to neurons in the neocortex development. Rbms1 expression is highest in the early development in the developing cortex, with its expression gradually diminishing from embryonic day 13.5 (E13.5) to postnatal day 0 (P0). From in utero electroporation (IUE) experiments when Rbms1 levels are knocked down in neuronal progenitors, their transition from multipolar to bipolar state is delayed and this is accompanied by a delay in radial migration of these cells. Reduced Rbms1 levels in vivo also reduces differentiation as evidenced by a decrease in levels of several differentiation markers, meanwhile having no significant effects on proliferation and cell cycle rates of these cells. As an RNA binding protein, we profiled the RNA binders of Rbms1 by a cross-linked-RIP sequencing assay, followed by quantitative real-time polymerase chain reaction verification and showed that Rbms1 binds and stabilizes the mRNA for Efr3a, a signaling adapter protein. We also demonstrate that ectopic Efr3a can recover the cells from the migration defects due to loss of Rbms1, both in vivo and in vitro migration assays with cultured cells. These imply that one of the functions of Rbms1 involves the stabilization of Efr3a RNA message, required for migration and maturation of neuronal progenitors in radial migration in the developing neocortex.

mTORC1-Inhibition Potentiating Metabolic Block by Tyrosine Kinase Inhibitor Ponatinib in Multiple Myeloma.

Studies in targeting metabolism in cancer cells have shown the flexibility of cells in reprogramming their pathways away from a given metabolic block. Such behavior prompts a combination drug approach in targeting cancer metabolism, as a single compound may not address the tumor intractability. Overall, mammalian target of rapamycin complex 1 (mTORC1) signaling has been implicated as enabling metabolic escape in the case of a glycolysis block. From a library of compounds, the tyrosine kinase inhibitor ponatinib was screened to provide optimal reduction in metabolic activity in the production of adenosine triphosphate (ATP), pyruvate, and lactate for multiple myeloma cells; however, these cells displayed increasing levels of oxidative phosphorylation (OXPHOS), enabling them to continue generating ATP, although at a slower pace. The combination of ponatinib with the mTORC1 inhibitor, sirolimus, blocked OXPHOS; an effect also manifested in activity reductions for hexokinase 2 (HK2) and glucose-6-phosphate isomerase (GPI) glycolysis enzymes. There were also remarkably higher levels of reactive oxygen species (ROS) produced in mouse xenografts, on par with increased glycolytic block. The combination of ponatinib and sirolimus resulted in synergistic inhibition of tumor xenografts with no overt toxicity in treated mice for kidney and liver function or maintaining weight.

Reversing the HDAC-inhibitor mediated metabolic escape in MYCN-amplified neuroblastoma.

In MYCN-amplified neuroblastoma (NB), we noticed that the single compound treatment with the HDAC inhibitor vorinostat led to a reprogramming of the glycolytic pathway in these cells. This reprogramming was upregulation of fatty acid oxidation (FAO) and oxidative phosphorylation (OXPHOS), allowing the cells to generate ATP, albeit at a reduced rate. This behavior was dependent on reduced levels of MYCN and a corresponding increase in the levels of PPARD transcription factors. By integrating metabolic and functional studies in NB cells and mouse xenografts, we demonstrate a compensatory upregulation of FAO/OXPHOS metabolism that promotes resistance to HDAC inhibitors. From the additional compounds that could reverse this metabolic reprogramming, the mTORC1 inhibitor sirolimus was selected. Besides both a block of glycolysis and OXPHOS, the HDAC/mTORC1 inhibitor combination produced significantly higher levels of reactive oxygen species (ROS) in the treated cells and in xenograft tumor samples, also a consequence of increased glycolytic block. The lead compounds were also tested for changes in the message levels of the glycolytic enzymes and their pathway activity, and HK2 and GPI glycolytic enzymes were most affected at their RNA message level. This combination was seen with no overall toxicity in treated mice in terms of weight loss or liver/kidney function.

RNA binding protein HuD promotes autophagy and tumor stress survival by suppressing mTORC1 activity and augmenting ARL6IP1 levels.

BACKGROUND: Neuronal-origin HuD (ELAVL4) is an RNA binding protein overexpressed in neuroblastoma (NB) and certain other cancers. The RNA targets of this RNA binding protein in neuroblastoma cells and their role in promoting cancer survival have been unexplored. In the study of modulators of mTORC1 activity under the conditions of optimal cell growth and starvation, the role of HuD and its two substrates were studied. METHODS: RNA immunoprecipitation/sequencing (RIP-SEQ) coupled with quantitative real-time PCR were used to identify substrates of HuD in NB cells. Validation of the two RNA targets of HuD was via reverse capture of HuD by synthetic RNA oligoes from cell lysates and binding of RNA to recombinant forms of HuD in the cell and outside of the cell. Further analysis was via RNA transcriptome analysis of HuD silencing in the test cells. RESULTS: In response to stress, HuD was found to dampen mTORC1 activity and allow the cell to upregulate its autophagy levels by suppressing mTORC1 activity. Among mRNA substrates regulated cell-wide by HuD, GRB-10 and ARL6IP1 were found to carry out critical functions for survival of the cells under stress. GRB-10 was involved in blocking mTORC1 activity by disrupting Raptor-mTOR kinase interaction. Reduced mTORC1 activity allowed lifting of autophagy levels in the cells required for increased survival. In addition, ARL6IP1, an apoptotic regulator in the ER membrane, was found to promote cell survival by negative regulation of apoptosis. As a therapeutic target, knockdown of HuD in two xenograft models of NB led to a block in tumor growth, confirming its importance for viability of the tumor cells. Cell-wide RNA messages of these two HuD substrates and HuD and mTORC1 marker of activity significantly correlated in NB patient populations and in mouse xenografts. CONCLUSIONS: HuD is seen as a novel means of promoting stress survival in this cancer type by downregulating mTORC1 activity and negatively regulating apoptosis.

The Role of Zinc in Axon Formation via the mTORC1 Pathway.

Zinc is an essential micronutrient required for proper function during neuronal development because it can modulate neuronal function and structure. A fully functional description of zinc in axonal processing in the central nervous system remains elusive. Here, we define the role of intracellular zinc in axon formation and elongation, involving the mammalian target of rapamycin complex 1 (mTORC1). To investigate the involvement of zinc in axon growth, we performed an ex vivo culture of mouse hippocampal neurons and administrated ZnCl2 as a media supplement. At 2 days in vitro, the administration of zinc induced the formation of multiple and elongated axons in the ex vivo culture system. A similar outcome was witnessed in callosal projection neurons in a developing mouse brain. Treatment with extracellular zinc activated the mTORC1 signaling pathway in mouse hippocampal neuronal cultures. The zinc-dependent enhancement of neuronal processing was inhibited either by the deactivation of mTORC1 with RAPTOR shRNA or by mTOR-insensitive 4EBP1 mutants. Additionally, zinc-dependent mTORC1 activation enhanced the axonal translation of TC10 and Par3 may be responsible for axonal growth. We identified a promising role of zinc in controlling axonogenesis in the developing brain, which, in turn, may indicate a novel structural role of zinc in the cytoskeleton and developing neurons.

Therapeutic effects of lysophosphatidylcholine in experimental sepsis.

Sepsis represents a major cause of death in intensive care units. Here we show that administration of lysophosphatidylcholine (LPC), an endogenous lysophospholipid, protected mice against lethality after cecal ligation and puncture (CLP) or intraperitoneal injection of Escherichia coli. In vivo treatment with LPC markedly enhanced clearance of intraperitoneal bacteria and blocked CLP-induced deactivation of neutrophils. In vitro, LPC increased bactericidal activity of neutrophils, but not macrophages, by enhancing H(2)O(2) production in neutrophils that ingested E. coli. Incubation with an antibody to the LPC receptor, G2A, inhibited LPC-induced protection from CLP lethality and inhibited the effects of LPC in neutrophils. G2A-specific antibody also blocked the inhibitory effects of LPC on certain actions of lipopolysaccharides (LPS), including lethality and the release of tumor necrosis factor-alpha (TNF-alpha) from neutrophils. These results suggest that LPC can effectively prevent and treat sepsis and microbial infections.

General Anesthesia During Neurodevelopment Reduces Autistic Behavior in Adult BTBR Mice, a Murine Model of Autism.

Preclinical studies suggest that repeated exposure to anesthetics during a critical period of neurodevelopment induces long-term changes in synaptic transmission, plasticity, and behavior. Such changes are of great concern, as similar changes have also been identified in animal models of neurodevelopmental disorders (NDDs) such as autism. Because of overlapping synaptic changes, it is also possible that anesthetic exposures have a more significant effect in individuals diagnosed with NDDs. Thus, we evaluated the effects of early, multiple anesthetic exposures in BTBR mice, an inbred strain that displays autistic behavior. We discovered that three cycles of sevoflurane anesthesia (2.5%, 1 h) with 2-h intervals between each exposure in late postnatal BTBR mice did not aggravate, but instead improved pathophysiological mechanisms involved with autistic behavior. Sevoflurane exposures restored E/I balance (by increasing inhibitory synaptic transmission), and increased mitochondrial respiration and BDNF signaling in BTBR mice. Most importantly, such changes were associated with reduced autistic behavior in BTBR mice, as sociability was increased in the three-chamber test and repetitive behavior was reduced in the self-grooming test. Our results suggest that anesthetic exposures during neurodevelopment may affect individuals diagnosed with NDDs differently.

Lysophosphatidylcholine-induced apoptosis in H19-7 hippocampal progenitor cells is enhanced by the upregulation of Fas Ligand.

Lysophospholipids regulate a wide array of biological processes including apoptosis and neutrophil migration. Fas/Apo-1 and its ligand (FasL) participate in neuronal cell apoptosis causing various neurological diseases. Here, we use hippocampal neuroprogenitor cells to investigate how lysophosphatidylcholine (LPC) induces apoptosis in H19-7 hippocampal progenitor cells via Fas/Fas ligand-mediated apoptotic signaling pathway. Exposed cells with LPC presented on apoptotic morphology, positive TUNEL staining, and DNA fragmentation. We found that the expression of FasL was increased after LPC treatment. Furthermore, LPC-induced H19-7 cell apoptosis was decreased by agonistic anti-FasL antibody. In addition to promotion of caspase cascade activity by LPC, the administration of the caspase inhibitor, DEVD-fmk, prevented H19-7 cell apoptosis. LPC also increased the activation of nuclear factor-kappaB (NF-kappaB), which in turn, significantly increased FasL mRNA level. The increase in FasL mRNA level by NF-kappaB transfection was significantly decreased in the presence of IkappaB-SR, a super-repressor of IkappaB. Taken together, these results demonstrate that LPC has the ability to induce apoptosis in H19-7 cells through the upregulation of FasL expression via NF-kappaB activation.

Age-dependent changes in calretinin immunoreactivity and its protein level in the gerbil hippocampus.

Calretinin (CR)-immunoreactive interneurons are well known as the interneuron specific interneurons in the hippocampus. CR-immunoreactive neurons form cellular network and regulate the activity of other GABAergic inhibitory interneurons in the hippocampus. In the present study, we investigated age-related changes in CR-immunoreactive neurons and protein levels in the gerbil hippocampus during normal aging. In all subregions of the gerbil hippocampus, the number of CR-immunoreactive neurons was significantly decreased in the postnatal month 6 (PM 6) group compared to that in the PM 1 group. Thereafter, CR-immunoreactive neurons were decreased with age. In addition, the number of CR-immunoreactive cells in the subgranular zone were significantly decreased in the PM 6 group. We also observed that CR protein levels were decreased gradually with age. These results indicate that both CR immunoreactivity and its protein level were decreased with age in the gerbil hippocampus during normal aging.

Identification and prevention of heterotopias in mouse neocortical neural cell migration incurred by surgical damages during utero electroporation procedures.

In utero electroporation (IUE) is a useful technique for gene delivery in embryonic mouse brain. IUE technique is used to investigate the mammalian brain development in vivo. However, according to recent studies, IUE methodology has some limitations like the formation of artificial ectopias and heterotopias at the micro-injection site. Thus far, the artificial heterotopias generated by physical trauma during IUE are rarely reported. Here, we reported the artificial heterotopias and ectopias generated from surgical damages of micropipette in detail, and moreover, we described the protocol to avoid these phenotypes. For the experimental purpose, we transferred empty plasmids (pCAGIG-GFP) with green fluorescent-labelled protein into the cortical cortex by IUE and then compared the structure of the cortex region between the injected and un-injected cerebral hemispheres. The coronary section showed that ectopias and heterotopias were appeared on imperfect-injected brains, and layer maker staining, which including Ctip2 and TBR1 and laminin, can differentiate the physical damage, revealing the neurons in artificial ectopic and heterotopic area were not properly arranged. Moreover, premature differentiation of neurons in ectopias and heterotopias were observed. To avoid heterotopias and ectopias, we carefully manipulated the method of IUE application. Thus, this study might be helpful for the in utero electroporator to distinguish the artificial ectopias and heterotopias that caused by the physical injury by microneedle and the ways to avoid those undesirable circumstances.

Phosphorylation of CREB, a cyclic AMP responsive element binding protein, contributes partially to lysophosphatidic acid-induced fibroblast cell proliferation.

Lysophospholipids regulate a wide array of biological processes including cell survival and proliferation. In our previous studies, we found that in addition to SRE, CRE is required for maximal c-fos promoter activation triggered by lysophosphatidic acid (LPA). c-fos is an early indicator of various cells into the cell cycle after mitogenic stimulation. However, role of CREB activation in LPA-stimulated proliferation has not been elucidated yet. Here, we investigate how LPA induces proliferation in Rat-2 fibroblast cell via CREB activation. We found that total cell number and BrdU-positive cells were increased by LPA. Moreover, levels of c-fos mRNA and cyclin D1 protein were increased via LPA-induced CREB phosphorylation. Furthermore, LPA-induced Rat-2 cell proliferation was decreased markedly by ERK inhibitor (U0126) and partially by MSK inhibitor (H89). Taken together, these results suggest that CREB activation could partially up-regulate accumulation of cyclin D1 protein level and proliferation of LPA-stimulated Rat-2 fibroblast cells.