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Masaaki Tsuda

Publications and source records attributed to Masaaki Tsuda.

18 recordsLinked to original sources
PubMed2006

Regulation of neurotrophin-3 gene transcription by Sp3 and Sp4 in neurons.

Neurotrophin-3 (NT-3), a neurotrophin member, plays crucial roles in neuronal development, function and plasticity. Previous studies have demonstrated that NT-3 gene transcription is driven by alternative promoters A and B, located upstream of exons 1A (EIA) and 1B (EIB), respectively. However, the transcription factors and DNA elements that drive NT-3 gene transcription remain to be identified. Here, we analysed the promoter region of the NT-3 gene and found that an NT-3 transcript containing EIB is predominantly expressed in cortical neurons which preferentially utilize promoter B, and two tandemly repeated GC-boxes, located between -100 and -60 base pairs within promoter B, are required for the transcription. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that both specificity protein (Sp)3 and Sp4 were able to bind to the Sp1 binding sequences within the GC boxes. Expression of dominant-negative Sp3 and Sp4 small interfering RNA in cortical neurons reduced the activity of the NT-3 gene promoter. Over-expression of Sp1 family members, especially Sp4, resulted in an increase of the NT-3 gene promoter. These findings indicate that the NT-3 gene is a target gene for Sp4 that is abundantly expressed in the brain.

Animals↗
PubMed2006

New sesquiterpene from Vietnamese agarwood and its induction effect on brain-derived neurotrophic factor mRNA expression in vitro.

Agarwood, one of the valuable non-timber products in tropical forest, is a fragrant wood, whose ethereal fragrance has been prized in Asia for incense in ceremony, as well as sedatives in traditional medicine. We separated the 70% EtOH extract of Vietnamese agarwood, which showed significant induction effect on brain-derived neurotrophic factor (BDNF) mRNA expression in rat cultured neuronal cells, to isolate a new compound and a 2-(2-phenylethyl)chromone derivative. The new compound was determined to be a spirovetivane-type sesquiterpene, (4R,5R,7R)-1(10)-spirovetiven-11-ol-2-one, by spectroscopic data and showed induction effect of BDNF mRNA.

Animals↗
PubMed2006

Trichoblastic infundibular cyst.

We report 4 cases of an infundibular cyst that histopathologically showed small papillary projections of follicular germinative cells emanating from the basal layer of the cyst wall. Some of these projections branched and formed a reticulated pattern. This cystic lesion is histopathologically distinctive. We propose to designate it as a trichoblastic infundibular cyst because its lining resembles that of an infundibular cyst, yet it has cells that resemble those of the follicular germ in its wall.

Adult↗
PubMed2006

Developmental expression of the SRF co-activator MAL in brain: role in regulating dendritic morphology.

The dynamic changes in dendritic morphology displayed by developing and mature neurons have stimulated interest in deciphering the signaling pathways involved. Recent studies have identified megakaryocytic acute leukemia (MAL), a serum response factor (SRF) co-activator, as a key component of a signaling pathway linking changes in the actin cytoskeleton to SRF-mediated transcription. To help define the role of this pathway in regulating dendritic morphology, we have characterized the pattern of MAL expression in the developing and adult brain, and have examined its role in regulating dendritic morphology in cultured cortical neurons. In histological studies of mouse brain, we found prominent expression of MAL in neurons in adult hippocampus and cerebral cortex. MAL immunostaining revealed localization of this protein in neuronal cell bodies and apical dendrites. During development, an increase in MAL expression occurs during the second post-natal week. Expression of dominant negative MAL constructs or MAL siRNA in cortical neurons grown in primary culture reduces the number of dendritic processes and decreases the basal level of SRF-mediated transcription. Taken together, these findings indicate that the MAL-SRF signaling pathway plays a key role in regulating dendritic morphology.

Animals↗
PubMed2005

Deltamethrin, a pyrethroid insecticide, is a potent inducer for the activity-dependent gene expression of brain-derived neurotrophic factor in neurons.

The mRNA expression of brain-derived neurotrophic factor (BDNF) is controlled in an activity-dependent manner through Ca(2+) influx into neurons. Pyrethroids are widely used insecticides of low acute toxicity in mammals, but their effects on sodium channels are known to lead to hyperexcitation in neuronal cells of insects. In this study, we found that deltamethrin, a type II pyrethroid insecticide, was highly effective in inducing BDNF expression in culture and in the rat brain. Addition of deltamethrin to rat cortical cells in culture markedly increased the expression of BDNF exon III-V mRNA and protein, dependent upon the neuronal activity accompanying the influx of Ca(2+) into neurons and the Ca(2+) influx-dependent phosphorylation of extracellular signal-regulated kinases 1/2. The elevated expression was maintained for at least 48 h, even after deltamethrin was withdrawn from the culture medium. Comparison of the effects of selected pyrethroids on the expression revealed that type II but not type I pyrethroids effectively induced BDNF mRNA expression. In addition, administration of deltamethrin to rats increased the level of BDNF protein in the cerebral cortex and hippocampus. These results indicate that deltamethrin is a potent inducer of BDNF expression in neurons and that it may induce neuronal hyperexcitation if it reaches the brain.

Anesthetics, Local↗
PubMed2005

Interference with activity-dependent transcriptional activation of BDNF gene depending upon the expanded polyglutamines in neurons.

Expanded polyglutamines (polyQ) have been demonstrated to impair the CREB-dependent transcription in established cell lines. Since activity-dependent transcription in neurons, which plays an important role in forming neuronal plasticity, is largely controlled by CREB, it is important to study whether polyQ interferes with the activity-dependent transcriptional activation of genes in neurons. In cultured rat cortical neurons, over-expression of truncated dentatorubral-pallidoluysian atrophy proteins containing expanded polyQ, which form aggregation bodies in nucleus, reduced the calcium (Ca(2+)) signal-mediated transcriptional activation of brain-derived neurotrophic factor, c-fos, and pituitary adenylate cyclase-activating polypeptide gene promoters in a dose-dependent manner. The interference with the transcriptional activation was dependent upon the presence of polyQ, the strength of which was increased as the length of polyQ stretches was expanded. Thus, polyQ interferes with the activity-dependent transcription in a polyQ-length-dependent manner, which may correspond to the severity of polyglutamine diseases.

Animals↗
PubMed2005

Transcriptional regulation of neuronal genes and its effect on neural functions: cumulative mRNA expression of PACAP and BDNF genes controlled by calcium and cAMP signals in neurons.

Although it is widely accepted that an activity-dependent gene transcription is induced by the calcium (Ca(2+)) signals in neurons, it is still unclear how the particular mRNA moieties are transiently accumulated in response to synaptic transmission that evokes multiple intracellular signals including Ca(2+) and cAMP ones. Promoters of the brain-derived neurotrophic factor (BDNF) and the pituitary adenylate cyclase-ativating polypeptide (PACAP) can commonly be activated through the cAMP-responsive element (CRE), to which the CRE-binding protein (CREB) predominantly bound. The activation of BDNF gene promoter I and III (BDNF-PI and -PIII, respectively) was mediated not only by the CREB but also by the upstream stimulatory factor, whereas that of PACAP gene promoter (PACAP-P) was mediated by only one CRE located at around -200. The PACAP-P was synergistically enhanced by Ca(2+) and cAMP signals through the CRE, whereas the BDNF-PI did not show such a synergistic activation upon the stimulation with both signals. In addition, we found that the half-lives of PACAP and BDNF mRNA were prolonged by the Ca(2+) influx into neurons but not that of Arc mRNA, indicating an activity-dependent stabilization of particular mRNA species in neurons. Thus, the activity-dependent gene expression is co-ordinately controlled by Ca(2+) and cAMP signals not only at the transcriptional level but also at the post-transcriptional level for the cumulative mRNA expression in neurons.

Animals↗
PubMed2005

Additional repression of activity-dependent c-fos and BDNF mRNA expression by lipophilic compounds accompanying a decrease in Ca2+ influx into neurons.

Recently, it has been proposed that a variety of environmental disruptors (EDs) disturb the neonatal development of the brain in mammals because of their lipophilic characteristics. Therefore, the synergism of these lipophilic compounds is important when evaluating the risk from EDs. In mouse cerebellar granule cells (CGCs), the activity-dependent expression of the brain-derived neurotrophic factor (BDNF) gene is activated through an influx of calcium ions (Ca2+) into CGCs caused by membrane depolarization, which is involved in the activity-dependent development of not only the cerebellum but also other regions of the brain after birth. In our previous study, we reported that permethrin and some other pyrethroid insecticides, which are suspected of being EDs, repressed the induction of c-fos and BDNF mRNA expression, accompanying a reduction of Ca2+ influx at doses non-toxic to CGCs. In the present study, we investigated whether other lipophilic compounds influenced the Ca2+ signal-induced expression of both genes as permethrin did and, if so, whether these effects were synergistic or additional. Pretreatment with p,p'-DDT, diethylstilbestrol (DES) or bisphenol A dose-dependently repressed the induction of both genes as well as the increase in the uptake of Ca2+ by CGCs. Simultaneous exposure of CGCs with permethrin, p,p'-DDT and DES, in addition, revealed an additional repression on the induction of the genes and the Ca2+ uptake. These results suggest that toxic effects of EDs might, at least additionally, occur in the brain even if the concentration of each compound is lower than the effective dose for humans.

Animals↗
PubMed2004

Activity-dependent transcriptional activation and mRNA stabilization for cumulative expression of pituitary adenylate cyclase-activating polypeptide mRNA controlled by calcium and cAMP signals in neurons.

Although it has been established that an activity-dependent gene transcription is induced by the calcium (Ca(2+)) signals in neurons, it is unclear how the specific mRNA moieties are transiently accumulated in response to synaptic transmission which evokes multiple intracellular signals including Ca(2+) and cAMP ones. The expression of pituitary adenylate cyclase activating polypeptide (PACAP), a neuropeptide, is controlled by Ca(2+) signals evoked via membrane depolarization in neurons, and, in cultured rat cortical neuronal cells, we found that the Ca(2+) signal-mediated activation of the PACAP gene promoter was critically controlled by a single cAMP-response element (CRE) located at around -200, to which the CRE-binding protein predominantly bound. The Ca(2+) signal-induced expression of PACAP mRNA was enhanced by forskolin, which evokes cAMP signals. In support, the PACAP gene promoter was synergistically enhanced by Ca(2+) and cAMP signals through the CRE, accompanying a prolonged activation of extracellular signal-related protein kinase 1/2 and CRE-binding protein. On the other hand, sole administration of forskolin markedly reduced the cellular content of PACAP mRNA, which was restored by the addition of Ca(2+) signals. We found that the stability of PACAP mRNA was increased in response to Ca(2+) signals but not that of activity-regulated cytoskeleton-associated protein (Arc) mRNA, indicating an activity-dependent stabilization of specific mRNA species in neurons, which can antagonize the regulation mediated by cAMP signals. Thus, the transcriptional activation and mRNA stabilization are coordinately regulated by Ca(2+) and cAMP signals for the cumulative expression of PACAP mRNA in neurons.

Animals↗
PubMed2004

Calcium signal-mediated expression of the vasoactive intestinal polypeptide gene and its small contribution to activity-dependent survival of mouse cerebellar granule cells.

We have demonstrated previously in primary cultures of mouse cerebellar granule cells (CGCs) that endogenously synthesized pituitary adenylate cyclase-activating polypeptide (PACAP) contributes at least in part to the activity-dependent survival of CGCs (Tabuchi et al. [2001] Neurosci. Res. 39:85-93). In this study, we have demonstrated that expression of vasoactive intestinal polypeptide (VIP), a member of the same VIP/secretin/glucagon family as PACAP, was activated markedly by Ca(2+) influx through L-type voltage-dependent Ca(2+) channels (L-VDCCs), which could be induced under the depolarizing condition induced by high concentration of potassium (K(+)) in the medium. The activation of VIP mRNA expression, different from that of PACAP, was dependent partly on de novo protein synthesis. On the other hand, mRNA expression of secretin and PACAP/VIP receptors (PAC(1), VPAC(1), and VPAC(2)) was not activated by the Ca(2+) influx; rather, PAC(1) mRNA expression was reduced. Exogenously added VIP prevented apoptosis of CGCs under nondepolarizing conditions, the effect of which was mediated specifically through the VPAC(1) receptor. Furthermore, the survival of CGCs under depolarizing conditions could be mediated partly through VPAC(1), the contribution of which was much less than that of PAC(1). These findings indicate that PACAP and VIP genes are coordinately activated by the Ca(2+) signals in CGCs, but the contribution of VIP to the activity-dependent survival of CGCs is quite small.

Action Potentials↗
PubMed2004

Activity-dependent increase in beta-amyloid precursor protein mRNA expression in neurons.

Although beta-amyloid precursor protein (APP) has been suggested to play a role in neuronal survival and plasticity, the mRNA expression of APP has not been studied in terms of neuronal activity. In cultures of mouse cerebellar granule cells, we found that the levels of APP mRNA increased when a high concentration of potassium was present in the medium. A deprivation of membrane depolarization caused by lowering the K+ concentration decreased both mRNA expression and protein synthesis of APP. Increasing the concentration, however, restored mRNA expression, which was driven by the influx of Ca2+ through L-type voltage-dependent calcium channels and mediated by de novo protein synthesis. Thus, APP mRNA expression is controlled in an activity-dependent manner in neurons.

Amyloid beta-Protein Precursor↗
PubMed2003

Brain-derived neurotrophic factor protects cultured rat hippocampal neurons from aluminum maltolate neurotoxicity.

Aluminum is environmentally abundant but not an essential trace element. Although there is increasing evidence suggesting the implication of aluminum in the pathogenesis of Alzheimer's disease, it is still controversial. We found and report here that aluminum maltolate, a stable and hydrophilic aluminum complex, causes death of primary cultured rat hippocampal neurons in a time- and dose-dependent manner. Degenerated neurons were TUNEL-positive. Immunohistochemical detection of synapsin I and microtubule associated protein 2 revealed the synapse loss between neurons intoxicated by aluminum maltolate. To explore the mechanism underlying its neurotoxicity, we administered various pharmacological compounds prior to the application of aluminum maltolate, and found that brain-derived neurotrophic factor (BDNF) markedly attenuated the neurotoxicity. Furthermore, aluminum maltolate inhibited the elevation of intracellular calcium levels caused by BDNF. Our results suggest the involvement of BDNF in the molecular mechanism underlying neurotoxicity induced by aluminum maltolate.

Animals↗
PubMed2003

Inactivation of aconitase during the apoptosis of mouse cerebellar granule neurons induced by a deprivation of membrane depolarization.

During the excitotoxic neuronal cell death which accompanies an overflow of extracellular Ca(2+) into neurons, aconitase, an oxidative stress-sensitive enzyme of the tricarboxylic acid (TCA)-cycle in mitochondria, is inactivated due to the generation of oxidative stress (Patel et al. [1996] Neuron 16:345-355). In this study, we investigated whether aconitase could be inactivated during the apoptosis of mouse cerebellar granule cells (CGCs), which was caused by a deprivation of membrane depolarization followed by a stoppage of Ca(2+) influx into CGCs. Upon lowering the potassium (K(+)) concentration in medium from 25 to 5 mM (low K(+)), aconitase was inactivated in accordance with the decrease in methylthiazoletetrazolium (MTT)-reducing activity although its mRNA expression did not change. The blockade of Ca(2+) influx into CGCs mediated by nicardipine at 25 mM KCl also caused the inactivation of aconitase, accompanying induction of the apoptosis of CGCs. Suppression of the apoptosis of CGCs mediated by the Ca(2+) influx or neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and adenylate cyclase activating polypeptide-38 (PACAP-38) attenuated the aconitase inactivation as well as the lactate dehydrogenase (LDH)-release and the decrease in MTT reduction. On the other hand, the levels of intracellular glutathione and manganese superoxide dismutase-2 mRNA decreased under the low K(+) condition, supporting a cause for oxidative stress at low K(+) due to a loss of anti-oxidant activity. Thus, the inactivation of aconitase is also caused by a deprivation of Ca(2+) influx into neurons, suggesting that aconitase is a key mitochondrial enzyme influencing the viability of neurons in response to oxidative stress.

Aconitate Hydratase↗
PubMed2002

Involvement of an upstream stimulatory factor as well as cAMP-responsive element-binding protein in the activation of brain-derived neurotrophic factor gene promoter I.

The use of different brain-derived neurotrophic factor (BDNF) gene promoters results in the differential production of 5'-alternative transcripts, suggesting versatile functions of BDNF in neurons. Among four BDNF promoters I, II, III, and IV (BDNF-PI, -PII, -PIII, and -PIV), BDNF-PI was markedly activated, as well as BDNF-PIII, by Ca(2+) signals evoked via neuronal activity. However, little is known about the mechanisms for the transcriptional activation of BDNF-PI. Using rat cortical neurons in culture, we assigned the promoter sequences responsible for the Ca(2+) signal-mediated activation of BDNF-PI and found that the Ca(2+)-responsive elements were located in two separate (distal and proximal) regions and that the DNA sequences in the proximal region containing cAMP-responsive element (CRE), which is overlapped by the upstream stimulatory factor (USF)-binding element, were largely responsible for the activation of BDNF-PI. CRE-binding protein (CREB) family transcription factors and USF1/USF2 bind to this overlapping site, depending upon their preferred sequences which also control the magnitude of the activation. Overexpression of dominant negative CREB or USF reduced the BDNF-PI activation. These findings support that not only CREB but also USF1/USF2 contributes to Ca(2+) signal-mediated activation of BDNF-PI through the recognition of an overlapping CRE and USF-binding element.

Animals↗
PubMed2002

Neonatal exposure of newborn mice to pyrethroid (permethrin) represses activity-dependent c-fos mRNA expression in cerebellum.

In a previous report, we demonstrated that the exposure of cultured mouse cerebellar granule cells to permethrin, a type I pyrethroid insecticide, repressed the induction of activity-dependent c- fos and brain-derived neurotrophic factor (BDNF) gene expression, accompanying a decrease in Ca(2+) influx into neurons. In addition, it has been suggested that some pyrethroids, including permethrin, are endocrine-modulating chemicals and accumulate in human breast milk. In this study, therefore, we investigated whether lactational exposure of newborn mice to permethrin influenced c- fos, BDNF and beta-actin gene expression in the developing neonatal cerebellum. In the cerebella of control neonates, c- fos mRNA expression was characterized by a significant increase in postnatal weeks 2 and 3, followed by a marked decrease. In the cerebella of permethrin-treated neonates, the expression of c- fos mRNA was dose-dependently repressed by cis-permethrin more effectively than by trans-permethrin at postnatal week 3, without alterations in the body or cerebellum weights of neonates. In the fourth and fifth week, however, c- fos mRNA expression had decreased to the same level as that in the control and permethrin-treated neonates. A decrease in BDNF mRNA expression tended to be observed in the cerebella of newborn mice on exposure to permethrin. Thus, our results indicate that the activity-dependent gene expressions in cerebellar neuronal cells can be repressed by permethrin both in vitro and in vivo, and suggest that lactational exposure to pyrethroids might affect the postnatal development of the mammalian brain.

Animals↗
PubMed2002

REST4-mediated modulation of REST/NRSF-silencing function during BDNF gene promoter activation.

Neural-restrictive silencer element (NRSE)/repressor element-1 (RE1) regulates neuron-specific gene expression by binding the transcriptional factor REST/NRSF which functions as a silencer in nonneuronal cells. In neuronal cells, a truncated, neuronal-specific REST/NRSF isoform, REST4, has been found but little is known about its function. To address this, we investigated the effect of REST/NRSF and REST4 on the activity-dependent activation of BDNF gene promoter I (BDNFp-I) using cultured rat cortical neurons. REST/NRSF markedly repressed the transcriptional activation of BDNFp-I, whereas the effect of REST4 was weak, depending upon the NRSE/RE1 sequence. In addition, REST4 enhanced the basal transcriptional activity of BDNFp-I. Coexpression of REST4 with REST/NRSF competitively inhibited the silencing effect of REST/NRSF on the activation of BDNFp-I. Although REST4 itself has a weak repressive effect on activation of the BDNF gene via NRSE/RE1, it can compete the silencing effect of REST/NRSF, suggesting a primary role for REST4 in preventing the neuron-specific gene from being inactivated by REST/NRSF and allowing gene activation in response to a variety of neuronal stimuli.

Animals↗