Embryonic Hippocampal Cell Research Articles

Exploring the Influence of Fok1/Apa1 Polymorphic Variants on Adolescent Mental Health and Response to Vitamin D Supplementation in Embryonic Hippocampal Cell Lines.

Several single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) have been observed in association with susceptibility to various pathologies, including autism, major depression, age-related changes in cognitive functioning, and Parkinson's and Alzheimer's diseases. This study aimed to establish the association between Fok1/Apa1 polymorphic variants and anxious/depressive symptoms in nonclinical adolescents from central Italy, with the goal of identifying the risk of developing both symptoms. We found no significant difference in genotype distribution or dominant/recessive models of Fok1/Apa1 VDR polymorphic variants between subjects with anxious/depressive symptoms and controls. HN9.10e cell lines carrying the AA genotype for Fok1 and the CC genotype for Apa1 responded better to treatment with vitamin D3 than cell lines carrying the AG genotype for Fok1 and CA genotype for Apa1. Cell lines carrying the GG genotype for Fok1 and the AA genotype for Apa1 did not respond at all, suggesting avenues for future studies in both the general population and individuals with mental and/or neuropsychiatric disorders. These studies suggest that the level of response to vitamin D3 administered to prevent and/or treat mental or neurological disorders could depend on the polymorphic variants of the vitamin D receptor.

RBM45 is an m6A-binding protein that affects neuronal differentiation and the splicing of a subset of mRNAs.

SUMMARYN6-methyladenosine (m6A) is deposited co-transcriptionally on thousands of cellular mRNAs and plays important roles in mRNA processing and cellular function. m6A is particularly abundant within the brain and is critical for neurodevelopment. However, the mechanisms through which m6A contributes to brain development are incompletely understood. RBM45 acts as an m6A-binding protein that is highly expressed during neurodevelopment. We find that RBM45 binds to thousands of cellular RNAs, predominantly within intronic regions. Rbm45 depletion disrupts the constitutive splicing of a subset of target pre-mRNAs, leading to altered mRNA and protein levels through both m6A-dependent and m6A-independent mechanisms. Finally, we find that RBM45 is necessary for neuroblastoma cell differentiation and that its depletion impacts the expression of genes involved in several neurodevelopmental signaling pathways. Altogether, our findings show a role for RBM45 in controlling mRNA processing and neuronal differentiation, mediated in part by the recognition of methylated RNA.

Vitamin D3 Enriches Ceramide Content in Exosomes Released by Embryonic Hippocampal Cells.

The release of exosomes can lead to cell–cell communication. Nutrients such as vitamin D3 and sphingolipids have important roles in many cellular functions, including proliferation, differentiation, senescence, and cancer. However, the specific composition of sphingolipids in exosomes and their changes induced by vitamin D3 treatment have not been elucidated. Here, we initially observed neutral sphingomyelinase and vitamin D receptors in exosomes released from HN9.10 embryonic hippocampal cells. Using ultrafast liquid chromatography tandem mass spectrometry, we showed that exosomes are rich in sphingomyelin species compared to whole cells. To interrogate the possible functions of vitamin D3, we established the optimal conditions of cell treatment and we analyzed exosome composition. Vitamin D3 was identified as responsible for the vitamin D receptor loss, for the increase in neutral sphingomyelinase content and sphingomyelin changes. As a consequence, the generation of ceramide upon vitamin D3 treatment was evident. Incubation of the cells with neutral sphingomyelinase, or the same concentration of ceramide produced in exosomes was necessary and sufficient to stimulate embryonic hippocampal cell differentiation, as vitamin D3. This is the first time that exosome ceramide is interrogated for mediate the effect of vitamin D3 in inducing cell differentiation.

Regulation of exosome secretion by cellular retinoic acid binding protein 1 contributes to systemic anti-inflammation

BackgroundIntercellular communications are important for maintaining normal physiological processes. An important intercellular communication is mediated by the exchange of membrane-enclosed extracellular vesicles. Among various vesicles, exosomes can be detected in a wide variety of biological systems, but the regulation and biological implication of exosome secretion/uptake remains largely unclear.MethodsCellular retinoic acid (RA) binding protein 1 (Crabp1) knockout (CKO) mice were used for in vivo studies. Extracellular exosomes were monitored in CKO mice and relevant cell cultures including embryonic stem cell (CJ7), macrophage (Raw 264.7) and hippocampal cell (HT22) using Western blot and flow cytometry. Receptor Interacting Protein 140 (RIP140) was depleted by Crispr/Cas9-mediated gene editing. Anti-inflammatory maker was analyzed using qRT-PCR. Clinical relevance was accessed by mining multiple clinical datasets.ResultsThis study uncovers Crabp1 as a negative regulator of exosome secretion from neurons. Specifically, RIP140, a pro-inflammatory regulator, can be transferred from neurons, via Crabp1-regulated exosome secretion, into macrophages to promote their inflammatory polarization. Consistently, CKO mice, defected in the negative control of exosome secretion, have significantly elevated RIP140-containing exosomes in their blood and cerebrospinal fluid, and exhibit an increased vulnerability to systemic inflammation. Clinical relevance of this pathway is supported by patients’ data of multiple inflammatory diseases. Further, the action of Crabp1 in regulating exosome secretion involves its ligand and is mediated by its downstream target, the MAPK signaling pathway.ConclusionsThis study presents the first evidence for the regulation of exosome secretion, which mediates intercellular communication, by RA-Crabp1 signaling. This novel mechanism can contribute to the control of systemic inflammation by transferring an inflammatory regulator, RIP140, between cells. This represents a new mechanism of vitamin A action that can modulate the homeostasis of system-wide innate immunity without involving gene regulation.EB6KXQYbkzhu3R444VcR3RVideo

Generation Dependent Effects and Entrance to Mitochondria of Hybrid Dendrimers on Normal and Cancer Neuronal Cells In Vitro.

Dendrimers as drug carriers can be utilized for drugs and siRNA delivery in central nervous system (CNS) disorders, including various types of cancers, such as neuroblastomas and gliomas. They have also been considered as drugs per se, for example as anti-Alzheimer’s disease (AD), anti-cancer, anti-prion or anti-inflammatory agents. Since the influence of carbosilane–viologen–phosphorus dendrimers (SMT1 and SMT2) on the basic cellular processes of nerve cells had not been investigated, we examined the impact of two generations of these hybrid macromolecules on two murine cell lines—cancer cell line N2a (mouse neuroblastoma) and normal immortalized cell line mHippoE-18 (embryonic mouse hippocampal cell line). We examined alterations in cellular responses including the activity of mitochondrial dehydrogenases, the generation of reactive oxygen species (ROS), changes in mitochondrial membrane potential, and morphological modifications and fractions of apoptotic and dead cells. Our results show that both dendrimers at low concentrations affected the cancer cell line more than the normal one. Also, generation-dependent effects were found: the highest generation induced greater cytotoxic effects and morphological modifications. The most promising is that the changes in mitochondrial membrane potential and transmission electron microscopy (TEM) images indicate that dendrimer SMT1 can reach mitochondria. Thus, SMT1 and SMT2 seem to have potential as nanocarriers to mitochondria or anti-cancer drugs per se in CNS disorders.

Hexagonal boron nitrides reduce the oxidative stress on cells

The molecular stress caused by a drug administered to treat a disorder on healthy cells appears as a side effect. In this study, we aim to understand the potential of hexagonal boron nitrides (hBNs) as a therapeutic agent to relieve the cellular stress exerted by drugs. First, the cytotoxicity of hBNs and their possible degradation product, boric acid (BA), on the embryonic mouse hippocampal cell line mHippo E-14 was assessed in a wide concentration range (4.4–440 μg ml−1) of boron including hBNs and BA for 24 and 72 h exposure. Then, cell cycle, reactive oxygen species generation, cell death mechanism and apoptotic body formation in nuclei with hBN and BA exposure were evaluated at increased concentrations and incubation times. Finally, the cells, exposed to doxorubicin (DOX), an anti-cancer chemotherapy drug, to exert oxidative stress, were treated with hBNs and BA. The results indicate that hBNs decrease the oxidative stress at the concentrations that are nontoxic to cells. The study suggests that hBNs can open new venues for their investigation to reduce or eliminate the adverse effects of toxic drugs used in the treatment of several fatal diseases including neurological disorders and cancer with their slow degradation feature.

Metabolic Stress Alters Antioxidant Systems, Suppresses the Adiponectin Receptor 1 and Induces Alzheimer's Like Pathology in Mice Brain.

Oxidative stress and insulin resistance play major roles in numerous neurodegenerative diseases, including Alzheimer’s disease (AD). A high-fat diet induces obesity-associated oxidative stress, neuronal insulin resistance, microglial activation, and neuroinflammation, which are considered important risk factors for neurodegeneration. Obesity-related metabolic dysfunction is a risk factor for cognitive decline. The present study aimed to elucidate whether chronic consumption of a high-fat diet (HFD; 24 weeks) can induce insulin resistance, neuroinflammation, and amyloid beta (Aβ) deposition in mouse brains. Male C57BL/6N mice were used for a high-fat diet (HFD)-induced pre-clinical model of obesity. The protein expression levels were examined via Western blot, immunofluorescence, and the behavior analysis was performed using the Morris water maze test. To obtain metabolic parameters, insulin sensitivity and glucose tolerance tests were performed. We found that metabolic perturbations from the chronic consumption of HFD elevated neuronal oxidative stress and insulin resistance through adiponectin receptor (AdipoR1) suppression in HFD-fed mice. Similarly, our in vitro results also indicated that knockdown of AdipoR1 in the embryonic mouse hippocampal cell line mHippoE-14 leads to increased oxidative stress in neurons. In addition, HFD markedly increased neuroinflammatory markers’ glial activation in the cortex and hippocampus regions of HFD mouse brains. More importantly, we observed that AdipoR1 suppression increased the amyloidogenic pathway both in vivo and in vitro. Furthermore, deregulated synaptic proteins and behavioral deficits were observed in the HFD mouse brains. Taken together, our findings suggest that excessive consumption of an HFD has a profound impact on brain function, which involves the acceleration of cognitive impairment due to increased obesity-associated oxidative stress, insulin resistance, and neuroinflammation, which ultimately may cause early onset of Alzheimer’s pathology via the suppression of AdipoR1 signaling in the brain.

Effect of Vitamin D in HN9.10e Embryonic Hippocampal Cells and in Hippocampus from MPTP-Induced Parkinson's Disease Mouse Model.

It has long been proven that neurogenesis continues in the adult brains of mammals in the dentatus gyrus of the hippocampus due to the presence of neural stem cells. Although a large number of studies have been carried out to highlight the localization of vitamin D receptor in hippocampus, the expression of vitamin D receptor in neurogenic dentatus gyrus of hippocampus in Parkinson’s disease (PD) and the molecular mechanisms triggered by vitamin D underlying the production of differentiated neurons from embryonic cells remain unknown. Thus, we performed a preclinical in vivo study by inducing PD in mice with MPTP and showed a reduction of glial fibrillary acidic protein (GFAP) and vitamin D receptor in the dentatus gyrus of hippocampus. Then, we performed an in vitro study by inducing embryonic hippocampal cell differentiation with vitamin D. Interestingly, vitamin D stimulates the expression of its receptor. Vitamin D receptor is a transcription factor that probably is responsible for the upregulation of microtubule associated protein 2 and neurofilament heavy polypeptide genes. The latter increases heavy neurofilament protein expression, essential for neurofilament growth. Notably N-cadherin, implicated in activity for dendritic outgrowth, is upregulated by vitamin D.

Interactions of Rat Embryonic Hippocampal Neuronal Stem Cell on Au‐nanowire Arrays and Gold Nano‐Film Surface

Hippocampal neuronal stem cell culture on the nano‐substrates has introduced new era in nano‐neuroscience research. Neurons were cultured on the gold nano‐wire and nano‐film surfaces to see the viability and interactions between neurons and nanoscale surfaces. Anodization of aluminum templates created nanoporous alumina tubes arranged parallel to each other and electrodeposition using gold solution (AuHCl4) resulted in arrays of gold nanowires (GNWs) inside the pores. For investigation of Au‐nano‐neuronal interactions we have cultured embryonic day 18 rat hippocampal neurons on the surface of gold nanowires and surfaces. For preliminary understanding of the neuronal growth and connectivity we studied the images of nano‐neuronal interactions by using optical, fluorescence and scanning electron microscopy (SEM). For adhesion of neurons to nano‐arrays and nano‐surfaces we used bioconjugating protein coating Poly‐D‐Lysine (PDL). The rat hippocampus tissues were mechanically dissolved into neuronal cells and cultured on top of the gold nano‐wire (GNW) and flim (GNF) surfaces and preserved at 37° C constant temperatures in a 5% CO2 incubator. These neurons on the GNW and GNF surfaces started to grow from day 2 and survived up to 25 days or more. The extracellular protein PDL acted as an intermediate substance for neurites growth on the nano films slips. Without a PDL coating layer showed no or very little growth of neurons on the GNF substrates. We demonstrated well‐defined neuronal networks on Au‐nanowire arrays and GNF. The neurons attached with the nanowires surfaces by PDL, which is a positively charged poly‐peptide and plays a vital role in neurites growth on the nanowire arrays. The pre‐and post‐synaptic effects of neuronal interactions on the surfaces of nanowires were measured by Ca+ imaging in keck microscope. This study is the initial result for implementing the gold nano‐substrates to record the electrical signals from the neurons through gold nano‐films or nano‐wires.Support or Funding InformationNSF

Characterisation of Signalling by the Endogenous GPER1 (GPR30) Receptor in an Embryonic Mouse Hippocampal Cell Line (mHippoE-18).

Estrogen can modulate neuronal development and signalling by both genomic and non-genomic pathways. Many of its rapid, non-genomic effects on nervous tissue have been suggested to be mediated via the activation of the estrogen sensitive G-protein coupled receptor (GPER1 or GPR30). There has been much controversy over the cellular location, signalling properties and endogenous activators of GPER1. Here we describe the pharmacology and signalling properties of GPER1 in an immortalized embryonic hippocampal cell line, mHippoE-18. This cell line does not suffer from the inherent problems associated with the study of this receptor in native tissue or the problems associated with heterologously expression in clonal cell lines. In mHippoE-18 cells, 17β-Estradiol can mediate a dose-dependent rapid potentiation of forskolin-stimulated cyclic AMP levels but does not appear to activate the ERK1/2 pathway. The effect of 17β-Estradiol can be mimicked by the GPER1 agonist, G1, and also by tamoxifen and ICI 182,780 which activate GPER1 in a variety of other preparations. The response is not mimicked by the application of the classical estrogen receptor agonists, PPT, (an ERα agonist) or DPN, (an ERβ agonist), further suggesting that this effect of 17β-Estradiol is mediated through the activation of GPER1. However, after exposure of the cells to the GPER1 specific antagonists, G15 and G36, the stimulatory effects of the above agonists are replaced by dose-dependent inhibitions of forskolin-stimulated cyclic AMP levels. This inhibitory effect is mimicked by aldosterone in a dose-dependent way even in the absence of the GPER1 antagonists. The results are discussed in terms of possible “Biased Antagonism” whereby the antagonists change the conformation of the receptor resulting in changes in the agonist induced coupling of the receptor to different second messenger pathways.

Serum deprivation alters lipid profile in HN9.10e embryonic hippocampal cells

The understanding of the mechanism of apoptosis is important to improve the use of stem cells for the treatment of neurodegenerative disorders. Sphingolipids are bioactive molecules involved in the regulation of cell fate. In HN9.10e embryonic hippocampal cells, serum deprivation induces apoptosis preceded by sphingomyelinase activation and raise of ceramide levels. Increasing evidence indicates that individual ceramide species regulated by specific pathways in distinct subcellular compartments might carry out distinct cellular functions, but the ceramides species involved in embryonic hippocampal cell death induced by growth factor deprivation are unknown. In the present paper, by using the UFLC–MS/MS methodology, we have investigated the effect of serum deprivation on the lipid profile in HN9.10e cells. At 48h of serum deprivation, we detected a decrease in cholesterol and increase in sphingosine-1-phoshate 18:1, phosphatidylcholine 18:1 18:0, sphingomyelin 18:1 16:0 and in ceramides 18:1 16:0; we also found an increase in saturated/unsaturated fatty acid ratio in sphingomyelin. We hypothesize that the rearrangement of sphingo- and glycerolipids with increase of saturated fatty acids in serum-deprivated, neural cells might represent a cellular response aimed at holding cholesterol inside the cells.

Lysophosphatidic acid activates β-catenin/T cell factor signaling, which contributes to the suppression of apoptosis in H19-7 cells

Lysophosphatidic acid (LPA) is a lipid growth factor that regulates diverse cell functions, including cell proliferation, survival and apoptosis. LPA has been demonstrated to be involved in the regulation of cortical neurogenesis by increasing the survival of neural precursors. Previously, we reported that LPA stimulated the inactivation of glycogen synthase kinase 3 (GSK3) via the G protein-coupled LPA1 and LPA2 receptors, by which apoptosis is suppressed in H19-7 cells [an embryonic hippocampal progenitor cell (HPC) line]. Increasing numbers of studies have demonstrated that certain G protein-coupled receptors activate β-catenin/T cell factor (TCF) signaling independently of Wnt, which is involved in cell fate determination, cell proliferation and cell survival. To determine whether LPA activates β-catenin-mediated transcriptional activation pathways and whether β-catenin/TCF signaling is involved in neurogenesis by controlling the survival of neural precursors, β-catenin/TCF signaling cascades induced by LPA were investigated in the HPCs. Activation of β-catenin/TCF signaling was determined by the nuclear translocation of β-catenin and the transcriptional activation of a TCF reporter gene. The activation of β-catenin/TCF signaling was blocked by pertussis toxin (PTX) and a protein kinase C (PKC) inhibitor. The expression of a constitutively active mutated form of GSK3β activated β-catenin/TCF signaling to comparable levels to those induced by LPA, and protected against apoptosis in differentiating H19-7 cells. These results showed that LPA activates β-catenin/TCF signaling in a PTX- and PKC-dependent manner, which contributes to LPA-induced cell survival in the HPCs. Activation of β-catenin/TCF signaling by LPA may be involved in neurogenesis by controlling the survival of neural precursors.

C-terminal processing of the teneurin proteins: Independent actions of a teneurin C-terminal associated peptide in hippocampal cells

Many neuropsychiatric conditions have a common set of neurological substrates associated with the integration of sensorimotor processing. The teneurins are a recently described family of proteins that play a significant role in visual and auditory development. Encoded on the terminal exon of the teneurin genes is a family of bioactive peptides, termed teneurin C-terminal associated peptides (TCAP), which regulate mood-disorder associated behaviors. Thus, the teneurin-TCAP system could represent a novel neurological system underlying the origins of a number of complex neuropsychiatric conditions. However, it is not known if TCAP-1 exerts its effects as part of a direct teneurin function, whereby TCAP represents a functional region of the larger teneurin protein, or if it has an independent role, either as a splice variant or post-translational proteolytic cleavage product of teneurin. In this study, we show that TCAP-1 can be transcribed as a smaller mRNA transcript. After translation, further processing yields a smaller 15 kDa protein containing the TCAP-1 region. In the mouse hippocampus, immunoreactive (ir) TCAP-1 is exclusively localized to the pyramidal layers of the CA1, CA2 and CA3 regions. Although the localization of TCAP and teneurin in hippocampal regions is similar, they are distinct within the cell as most ir-teneurin is found at the plasma membrane, whereas ir-TCAP-1 is predominantly found in the cytosol. Moreover, in mouse embryonic hippocampal cell culture, FITC-labeled TCAP-1 binds to the plasma membrane and is taken up into the cytosol via dynamin-dependent caveolae-mediated endocytosis. Our data provides novel evidence that TCAP-1 is structurally and functionally distinct from the larger teneurins.

Interactions of Rat Embryonic Hippocampal Neuronal Stem Cell on Gold Nano‐Film Surface

Hippocampal neuronal stem cell culture on the nano‐substrates has introduced new era in nano‐neuroscience research. Neurons were cultured on the gold nano‐film surfaces to see the viability and interactions between neurons and nanoscale surfaces. Embryonic day 18 rat hippocampus tissues were mechanically dissolved into neuronal cells and cultured on top of the gold nano‐flim (GNF) surfaces and preserved at 370 C constant temperatures in a 5% CO2 incubator. These neurons on the GNF surfaces started to grow from day 2 and survived up to 25 days or more. For adhesion and growth of neurons we used an external coating protein, Poly‐D‐Lysine (PDL) layer on the top of the GNF. The extracellular protein PDL acted as an intermediate substance for neurites growth on the gold nano films slips. Without a PDL coating layer showed no or very little growth of neurons on the GNF surfaces. This study is the initial result for implementing the gold nano‐substrates to record the electrical signals from the neurons through gold nano‐films or nano‐wires.

Nuclear lipid microdomains regulate nuclear vitamin D3uptake and influence embryonic hippocampal cell differentiation

Despite recent advances in the understanding of the role of 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) in the CNS, the mechanism of action remains obscure. We demonstrate that some 1,25-(OH)(2)D(3) receptor (VDR) is localized in the cell nucleus in specialized microdomains enriched in sphingomyelin and cholesterol; the integrity of these microdomains is necessary for embryonic hippocampal cell differentiation. Sphingomyelinase (SMase) treatment reduces both VDR and labeled 1,25-(OH)(2)D(3) content in nuclear microdomains. We have previously shown that HN9.10e embryonic hippocampal cells differentiate when incubated with 100 nM 1,25-(OH)(2)D(3) in the presence of 10% fetal calf serum, while serum deprivation induces cell death. In this study, we have investigated whether conditions that alter lipid content of nuclear microdomains modify 1,25-(OH)(2)D(3)-induced differentiation. Serum deprivation activates SMase and modifies the composition of nuclear microdomains, which lose the 1,25-(OH)(2) vitamin D(3) receptor. The incubation of serum-deprived cells with 100 nM 1,25-(OH)(2)D(3) prevents differentiation. However, treatment with 400 nM 1,25-(OH)(2)D(3) during serum withdrawal increases the lipid content of the nuclear microdomains, allows the interaction of 1,25-(OH)(2)D(3) with its receptor, and results in differentiation. These results suggest the presence of VDR in nuclear microdomains is necessary for 1,25-(OH)(2)D(3)-induced differentiation in embryonic hippocampal cells.

Estrogen receptor alpha and G-protein coupled receptor 30 mediate the neuroprotective effects of 17β-estradiol in novel murine hippocampal cell models

The hippocampus is a multifaceted, complex brain structure considered to be the learning center. The use of primary hippocampal cell cultures has uncovered important cellular mechanisms involved in overall physiological function. Yet, the use of primary culture is inherently difficult, and the lack of immortalized cell lines from the murine hippocampus for mechanistic studies at the molecular level is evident. We have immortalized cell lines from embryonic (E18) and adult-derived hippocampal primary cell culture using retroviral infection of SV40 T-antigen. Four clonal embryonic lines, mHippoE-2, mHippoE-5, mHippoE-14, mHippoE-18, and one mixed adult line, mHippoA-mix, exhibited neuronal morphologies with neurite extensions and expression of neuronal markers, with unique gene expression profiles. We used these cell models to study the neuroprotective effects of 17β-estradiol (E2) on glutamate-induced neurotoxicity. The cell lines express a relevant array of genes and receptors suggested to play a role in neuroprotection, including estrogen receptors ERα, ERβ, and GPR30. We find that pretreatment with E2 (10 or 100 nM) for 24 h significantly reduced cell death induced by glutamate mHippoE-14 and mHippoE-18 cells, but not the mHippoA-mix. Using 24 h pretreatment with the specific estrogen receptor (ER) agonists, 4,4′,4′′-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) and diarylpropionitrile, 2,3-bis(4-Hydroxyphenyl)-propionitrile (DPN), we linked the E2-mediated neuroprotection to ERα, but only in the mHippoE-18 cells. Since E2 activated both PI3K/Akt and STAT3 signaling pathways, we also tested whether the membrane-bound E2 receptor GPR30 was involved in its neuroprotective action. Pretreatment with the GPR30 agonist G-1 (10 and 100 nM) for 1 h, but not 24 h, significantly attenuated cell death in both mHippoE-14 and mHippoE-18 cells. The use of specific ER antagonist ICI 182780 and GPR30 antagonist G-15 linked these effects to both ER and GPR30 receptors. This is the first evidence that GPR30 may play a role in the protective effects of estrogen in hippocampal neurons.

MicroRNA-101 Regulates Amyloid Precursor Protein Expression in Hippocampal Neurons

The amyloid precursor protein (APP) and its proteolytic product amyloid beta (Abeta) are associated with both familial and sporadic forms of Alzheimer disease (AD). Aberrant expression and function of microRNAs has been observed in AD. Here, we show that in rat hippocampal neurons cultured in vitro, the down-regulation of Argonaute-2, a key component of the RNA-induced silencing complex, produced an increase in APP levels. Using site-directed mutagenesis, a microRNA responsive element (RE) for miR-101 was identified in the 3'-untranslated region (UTR) of APP. The inhibition of endogenous miR-101 increased APP levels, whereas lentiviral-mediated miR-101 overexpression significantly reduced APP and Abeta load in hippocampal neurons. In addition, miR-101 contributed to the regulation of APP in response to the proinflammatory cytokine interleukin-1beta (IL-lbeta). Thus, miR-101 is a negative regulator of APP expression and affects the accumulation of Abeta, suggesting a possible role for miR-101 in neuropathological conditions.

Effect of 1α,25‐dihydroxyvitamin D3 in embryonic hippocampal cells

Although the role of 1alpha,25-dihydroxyvitamin D3 in calcium homeostasis of bone tissue is clear, evidence of the involvement of vitamin D3 in the central nervous system functions is increasing. In fact, vitamin D3 regulates vitamin D receptor and nerve growth factor expression, modulates brain development, and reverses experimental autoimmune encephalomyelitis. Only few studies, however, address vitamin D3 effect on embryonic hippocampal cell differentiation. In this investigation, the HN9.10e cell line was used as experimental model; these cells, that are a somatic fusion product of hippocampal cells from embryonic day-18 C57BL/6 mice and N18TG2 neuroblastoma cells, show morphological and cytoskeletal features similar to their neuronal precursors. By this model, we have studied the time course of vitamin D3 localization in the nucleus and its effect on proteins involved in proliferation and/or differentiation. We found that the translocation of vitamin D3 from cytoplasm to the nucleus is transient, as the maximal nuclear concentration is reached after 10 h of incubation with (3)H-vitamin D3 and decreases to control values by 12 h. The appearance of differentiation markers such as Bcl2, NGF, STAT3, and the decrease of proliferation markers such as cyclin-1 and PCNA are late events. Moreover, physiological concentrations of vitamin D3 delay cell proliferation and induce cell differentiation of embryonic cells characterized by modification of soma lengthening and formation of axons and dendrites.

Thematic Review Series: Sphingolipids. Nuclear sphingolipids: metabolism and signaling

Sphingolipids are most prominently expressed in the plasma membrane, but recent studies have pointed to important signaling and regulatory roles in the nucleus. The most abundant nuclear sphingolipid is sphingomyelin (SM), which occurs in the nuclear envelope (NE) as well as intranuclear sites. The major metabolic product of SM is ceramide, which is generated by nuclear sphingomyelinase and triggers apoptosis and other metabolic changes. Ceramide is further hydrolyzed to free fatty acid and sphingosine, the latter undergoing conversion to sphingosine phosphate by action of a specific nuclear kinase. Gangliosides are another type of sphingolipid found in the nucleus, members of the a-series of gangliotetraose gangliosides (GM1, GD1a) occurring in the NE and endonuclear compartments. GM1 in the inner membrane of the NE is tightly associated with a Na(+)/Ca(2+) exchanger whose activity it potentiates, thereby contributing to regulation of Ca(2+) homeostasis in the nucleus. This was shown to exert a cytoprotective role as absence or inactivation of this nuclear complex rendered cells vulnerable to apoptosis. This was demonstrated in the greatly enhanced kainite-induced seizure activity in knockout mice lacking gangliotetraose gangliosides. The pathology included apoptotic destruction of neurons in the CA3 region of the hippocampus. Ca(2+) homeostasis was restored in these animals with LIGA-20, a membrane-permeant derivative of GM1 that entered the NE and activated the nuclear Na(+)/Ca(2+) exchanger. Some evidence suggests the presence of uncharged glycosphingolipids in the nucleus.

Curcumin의 전처리는 excitotoxin에 의한 세포사멸로부터 해마신경세포를 보호

Curcumin은 자연에 존재하는 황색의 페놀성분의 커리 향신료이며 항산화 및 항염증의 성질을 가지고 있어서 산화 스트레스와 면역염증과 관련한 여러 질병의 치료로 사용되어져 왔다. 이러한 curcumin의 항산화 및 항염증 효과는 여러 퇴행성 신경질환으로부터 뇌를 보호하는데 유용하게 적용될 수 있다. 본 연구에서는 glutamate에 의한 excitotoxicity로부터 해마신경세포를 보호하는 curcumin의 신경보호효과에 대하여 보고한다. 태아 생쥐의 해마로부터 얻어진 신경세포를 저농도의 curcumin으로 전처리한 경우, 신경세포는 glutamate에 의한 세포사멸로부터 보호되었다. 그러나 이러한 신경보호효과는 산화스트레스의 조절과는 무관하였다. 흥미롭게도 고농도의 curcumin전처리는 오히려 초대배양 신경세포의 세포사멸을 유도하였다. 해마신경세포에서 스트레스 반응 단백질인 HSP70이 저농도의 curcumin을 처리하였을 때 현저하게 증가하였으며 반면 세포사멸의 마커인 절단된 PARP의 양은 고농도의 curcumin을 처리하였을 때 급증함이 immunoblot분석을 통하여 관찰되었다. 이러한 발견은 curcumin이 excitotoxin인 glutamate에 대한 신경세포의 반응을 조절할 수 있음을 보여주고 curcumin과 관련 화합물들의 퇴행성 신경질환에서의 예방 및 치료법으로의 가능성을 제시하고 있다. Curcumin is a natural phenolic yellow curry spice, derived from the tumeric, which has been used for the treatment of diseases associated with oxidative stress and inflammation. Curcumin is known to have both anti-oxidative and anti-inflammatory properties. These properties can be beneficial to protect the brain from the neurodegenerative diseases. We now report the neuroprotective effects of curcumin pretreatment in primary hippocampal neurons to glutamate-induced excitotoxicity. Pretreatment of embryonic mouse hippocampal cell cultures with low does of curcumin protected neurons against glutamate-induced death, however, this neuroprotection was not correlated with the modulation of oxidative stress. Interestingly, high dose of curcumin showed the cytotoxicity in primary cultured hippocampal neurons. Immunoblot analyses showed that levels of stress response. protein HSP70 were significantly elevated in neurons exposed to low dose of curcumin, whereas levels of cleaved PARP were increased in neurons exposed to high dose of curcumin. These findings show that curcumin can modulate neuronal responses to glutamate, and suggest possible use of curcumin and related compounds in the prevention and/or treatment of neurodegenerative disorders.