- Email: [email protected]
Axon growth inhibition meadiated by p75-PIR-B receptor complex
Abstracts
S83
and integrity of PF synapses were lost. Although induction of motor memory of EBC requires intact PF synapses, retention and extinction of memories do not. These results support the view that the trace of motor memory is initially acquired in cerebellar cortex, and later transferred to different brain regions for consolidation.
P1-b31 Roles of Rabaptin-5 in AMPA receptor trafficking Kazuyuki Kiyosue, Kimihiko Kameyama
doi:10.1016/j.neures.2009.09.318
Recent studies reveal that AMPA receptors at postsynaptic membrane are constitutively cycled but kept in the number to mediate a constant synaptic response. Although AMPA receptor trafficking to endosome and from recycling endosome has reported to be critical steps for the expression of LTD and LTP, receptivity, there is no information about AMPA receptor trafficking from early endosome to recycling endosome. We focused on Rabaptin-5, because that molecule is a putative mediator molecule for receptor trafficking at the pathway. Analysis of Rabaptin-5 molecules by immunostainings revealed that Rabaptin-5 puncta were closely localized to postsynaptic densities. Over-expression of Rabaptin-5 promoted biased AMPA receptor trafficking. These results suggest that Rabaptin-5 has a role for selective receptor trafficking at postsynaptic sites.
P1-b28 Characterization of novel C1q family proteins in adult brain Eriko Miura 1,2 , Takatoshi Iijima 1 , Tetsuro Kondo 1,3 , Masahiko Watanabe 2 , Michisuke Yuzaki 1 1
Dept. Physiol., Keio Univ. Sch. of Med., Tokyo, Japan; 2 Dept. Anat., Hokkaido Univ. Sch. of Med., Hokkaido, Japan; 3 Mol. Neurophysiol, AIST, Tsukuba, Japan The C1q family proteins are involved in various intercellular processes, such as inflammation and cell differentiation. Although some C1q family members are expressed in the CNS, their functions have not been characterized well. Cbln1, a member of the Cbln subfamily of the C1q family, was recently shown to be released from granule cells and play crucial roles for synaptic integrity and plasticity in the cerebellum. Here we characterized the C1ql subfamily, composed of C1ql1-C1ql4. By in situ hybridization, each C1ql member had distinct spatial expression pattern outside the cerebellum. In addition, C1ql2 and C1ql3 mRNAs were coexpressed in the dentate gyrus of the hippocampus. Indeed, we found that all C1ql members were secreted and formed both homomer and heteromer each other. These results indicate that like Cbln, C1ql subfamily members may also serve as transneuronal regulators of synaptic functions in various brain regions. doi:10.1016/j.neures.2009.09.319
P1-b29 Acute administration of the neurosteroid DHEAS primes LTP induction in rat hippocampal slices via mGluR5 and cannabinoid 1 receptor Yuxia Xu 1 , Ling Chen 2 , Masahiro Sokabe 1,3 1
Dept. Physiol., Nogoya Univ., Grad. Sch. Med., Nagoya, Japan; 2 Dept. Physiol., Nanjing Med. Univ., Nanjing, China; 3 ICORP/SORST Cell Mechanosening, JST, Nagoya, Japan We have reported previously that chronic administration of DHEAS to adult rats facilitates LTP induction in the hippocampus (Chen et al., 2006), however, its process and mechanisms are unknown. To address these questions, the present study investigated the acute effects of DHEAS on rat hippocampal slices. A low dose of DHEAS (100 nM for 10 min) instantly caused a short term potentiation (STPDHEAS ) lasting for 30 min. Interestingly, after the termination of STPDHEAS , robust LTP could be induced by a sub-threshold tetanus of 20 pulses at 100 Hz, whereas 100 pulses at 100 Hz did not, which roughly resembles the chronic DHEAS effect. The facilitated LTP induction was inhibited by the antagonists of mGluR5 receptor and cannabinoid 1 receptor (CB1R), suggesting that DHEAS induces STPDHEAS , during which an mGluR5 and CB1R dependent priming mechanism for a following LTP induction has been established. doi:10.1016/j.neures.2009.09.320
P1-b30 Spine formation pattern of new neurons is modulated by induction of long-term potentiation (LTP) in adult dentate gyrus Noriaki Ohkawa 1,2 , Yoshito Saitoh 1,2 , Eri Tokunaga 1,2 , Toshio Kitamura 3 , Kaoru Inokuchi 1,2 1
Mitsubishi Kagaku Inst. Life Sci., Tokyo, Japan; Med. Sci., Univ. Tokyo, Tokyo, Japan
2
JST, CREST, Japan;
3
Inst.
In dentate gyrus of adult hippocampus, newborn neurons are functionally integrated into the existing circuits. It remains unclear whether the integration of new neurons into preexisting circuits is modulated by the acquisition of new information. We constructed a compatible system of retrovirus-mediated spine labeling of new neurons and in vivo LTP induction in dentate gyrus. LTP was induced at 12, 16 or 21 days postinfection (dpi) at which new neurons have no, few, or many spines, respectively, and spine expression pattern was observed at 28 dpi when sharp increment of the spine density is terminated. LTP induction at different dpi differentially regulated the density and size of spines on new neurons, suggesting that the acquisition of new information differentially regulates the integration of newly born neurons dependent on their developmental stages. Thus, new neurons at different stages may play different roles in processing the acquired information. doi:10.1016/j.neures.2009.09.321
National Institute of Advanced Industrial Science and Technology (AIST), Japan
doi:10.1016/j.neures.2009.09.322
P1-b32 Properties of quantal excitatory events in the central amygdala in neuropathic rats Yukari Takahashi 1 , Ayano Nakao-Iwase 1 , Ryo Ikeda 2 , Fusao Kato 1 1
Lab. Neurophysiol., Jikei Univ. Sch. Med., Tokyo, Japan; Jikei Univ. Sch. Med., Tokyo, Japan
2
Dept. Orthoped.,
The spino-parabrachio (PB)-amygdaloid pathway terminating in the laterocapsular part (CeLC) of the central amygdala plays an important role in the expression of pain-related negative emotion. The PB-CeLC synaptic transmission contralateral to the neuropathic side becomes potentiated without affecting paired-pulse ratio, leading to a hypothesis that postsynaptic mechanisms underlie this plasticity (Ikeda et al., 2007). To examine this, quantal events were recorded in the presence of Sr2+ . The asynchronous EPSCs from the potentiated side showed slightly but significantly larger amplitude, while the decay time constant was not significantly different. The average ratios of synchronous EPSC amplitude to asynchronous one were 55.5 and 23.0 in the potentiated and contralateral, respectively, CeLC. These data suggest increased number of synchronously released vesicles and a slight increase in postsynaptic AMPA receptor density underlie the synaptic potentiation by neuropathic pain. doi:10.1016/j.neures.2009.09.323
P1-b33 Proteolytic processing of protein-tyrosine phosphatase receptor type Z Akihiro Fujikawa 1 , Jeremy P.H. Chow 1,2 , Hidetada Shimizu 1 , Ryoko Suzuki 1 , Masaharu Noda 1,2 1
Div. Mol. Neurobio., NIBB, Okazaki, Japan; Stud., Okazaki, Japan
2
Sch. Life Sci., Grad. Univ. Adv.
Protein-tyrosine phosphatase receptor type Z (Ptprz) is preferentially expressed in the brain as a major chondroitin sulfate proteoglycan. Here, we show that the extracellular region of the receptor isoforms of Ptprz are cleaved by plasmin and metalloproteinases, and subsequently the membrane-tethered fragment is cleaved by gamma-secretase, releasing its intracellular region into the cytoplasm; of note, the intracellular fragment of Ptprz shows nuclear localization. The proteolytic processing of Ptprz by plasmin was markedly enhanced after kainic acid induced seizures in the mouse brain. Administration of GM6001, a metalloproteinase inhibitor, to mice demonstrated the metalloproteinase-mediated cleavage of Ptprz under physiological conditions. Furthermore, we mapped plasmin cleavage sites of Ptprz, and identified the cleavage sites by tumor necrosis factor-alpha converting enzyme (TACE) and matrix metalloproteinase 9. These findings indicate that Ptprz is a novel target for activity-dependent proteolytic processing in the central nervous system. doi:10.1016/j.neures.2009.09.324
P1-b34 Axon growth inhibition meadiated by p75-PIR-B receptor complex Yuki Fujita, Toshihide Yamashita Dept. Mol. Neurosci., Grad. Sch. Med., Osaka Univ., Osaka, Japan Myelin inhibitors, MAG, Nogo, OMgp inhibit axon regeneration. They bind to the same receptor, NgR. Recent study shows PIR-B is a second receptor for myelin inhibitors but its mechanism remains unclear. Our aim is to understand the molecular mechanism of axon growth inhibition mediated by PIR-B. Because p75 receptor is involved in the regulation of axon regeneration by myelin inhibitors, we investigate the interaction of p75 with PIR-B by co-immunoprecipitation. We also analyzed
S84
Abstracts
whether this interaction depends on the ligand binding to the receptor. In consequence, p75 interacts with PIR-B regardless of with or without MAG-Fc treatment in cerebellar glanule neurons. Downstream of this receptor complex, SHP is associated with the effector of MAG-Fc. Our results suggest that p75 associates with PIR-B to mediate the action of myelin-associated neurite growth inhibition. doi:10.1016/j.neures.2009.09.325
P1-b35 Diacylglycerol kinase  promotes dendritic outgrowth and spine maturation in developing hippocampal neurons Yasukazu Hozumi, Kaoru Goto Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan Diacylglycerol kinase (DGK) is involved in the intracellular signal transduction as a regulator of two second messengers, diacylglycerol and phosphatidic acid. Recently, we have reported that DGK is expressed in medium spiny neurons of the striatum and is highly concentrated at the perisynapse of dendritic spines. Furthermore, one of the transcripts derived from the human DGK locus is annotated in GenBank as being differentially expressed in bipolar disorder patients. However, it remains elusive how DGK is implicated in pathophysiological role in neurons at the cellular level. In the present study, we investigated a potential involvement of DGK in spine morphogenesis in transfected hippocampal neurons. We suggest that DGK is involved in the molecular machinery of dendrite outgrowth and spinogenesis through its kinase activity. doi:10.1016/j.neures.2009.09.326
P1-b36 Dendritic shape and EPSP conduction of cortical nonpyramidal cells Yoshiyuki Kubota 1 , Fuyuki Karube 1 , Masaki Nomura 2 , Toshio Aoyagi 2 , Yasuo Kawaguchi 1 1
Div. Cerebral Circuitry, NIPS, Okazaki, Japan; Informatics, Kyoto, Japan
2
Kyoto University Grad. Sch.
Dendritic morphology greatly influences neuronal synaptic signal integration. Dendritic arborization patterns and local dimensions were analyzed in four subtypes of neocortical GABAergic cells. The dendritic local size parameters were obtained by 3-dimensional reconstruction of serial ultrathin sections. The cross-sectional areas of dendrites were well correlated with the summated dendritic length between the measured point and end tips. At branch points, the cross-sectional area of the mother dendrite was almost equal to the sum of those of the two daughter branches. Following these morphological rules, we constructed computational model neurons and analyzed the passive conduction property of EPSP along the dendrite. The simulation studies revealed that the most synaptic excitatory inputs on various dendrite locations generate similar somatic depolarizations. These results suggest the 3-dimensional dendritic shape is formed to increase the equality among various excitatory inputs distributed along the dendrites. doi:10.1016/j.neures.2009.09.327
P1-c01 The effects of a novel anti-Parkisonian drug on dopamine syshesis and vesicular dopamine uptake in dopaminergic cells Taisuke Yamagiwa, Shintaro Yasui, Hiroko Inoue Graduate School of Advanced Science and Engineering, Waseda Univeersity, Tokyo, Japan An antiepileptic drug has recently been shown to exert beneficial effects in Parkinson’s disease. However, the mechanism of the anti-Parkinsonian effects of the drug remains unclear. In this study, we attempted to elucidate the effects of the antiepileptic drug on dopamine synthesis and vesicular dopamine storage in dopaminergic cells. We examined the effects of the drug on tyrosine hydroxylase (TH), the rate limiting enzyme in dopamine synthesis, in PC12 cells. The enzyme activity was increased by the treatment of the drug, although the expression level of TH was not altered. We also examined the effects of the drug on cytosolic dopamine uptake into secretory vesicles via vesicular monoamine transporter 2 in PC12 and SH-SY5Y cells. doi:10.1016/j.neures.2009.09.328
P1-c02 Regulation of alpha CaMKII-activation in living cells Kenichi Kato, Satoshi Kida Dep. of Bioscience, Tokyo Univ. of Agriculture, Tokyo, Japan
Increase in intracellular Ca2+ concentration has been shown to lead to the activation of ␣CaMKII thorough the interaction with Ca2+ /CaM (CaM-interaction) followed by the conformational change of this kinase. To understand the regulation of ␣CaMKII activity in vivo, we have investigated CaM-interaction and conformational change of ␣CaMKII in living cells using FRET. In this study, we compared dynamics of ␣CaMKII activation in several types of cells. In HeLa cells and SH-SY5Y cells, long-term increase in Ca2+ induced continuous CaM-interaction and conformational change of ␣CaMKII, while short-term increase induced only transient CaM-interaction but maintained the conformational change of ␣CaMKII even after the dissociation of CaM. Interestingly, we observed similar changes of CaM-interaction and conformational changes of ␣CaMKII in cortical neurons in response to long or short-term application, respectively, of NMDA. These findings suggest that differences of intracellular Ca2+ dynamics lead to distinct patterns of ␣CaMKII activation. doi:10.1016/j.neures.2009.09.329
P1-c03 Estimation of intracellular calcium ion concentration and Ca influx by nonlinear state space modeling Takamasa Tsunoda 1 , Toshiaki Omori 2,3 , Hiroyoshi Miyakawa 4 , Masato Okada 2,3 , Toru Aonishi 1,3 1
Tokyo Tech., Japan; 2 Univ. of Tokyo, Japan; Univ. of Pharm, Japan
3
RIKEN BSI, Japan;
4
Tokyo
Calcium imaging method has superior ability in recording of spatial-temporal variations of ion concentrations. However, it has two major problems. First, the imaging signals are too noisy. Second, the observation data are the fluorescent intensities of Ca2+ indicator dyes that are only indirect information about the Ca2+ concentration. We devised an algorithm based on a nonlinear state-space approach for estimating the Ca2+ concentration and the Ca influx from the noisy fluorescent signals. First, we made a state-space model for the fluorescent signal series including Ca kinetics and a noisy fluorescent intensity pickup process. Then, we derived recursive update equations for one-step-ahead prediction, filtering and smoothing, and devised an EM (Expectation Maximization) algorithm for determining the model parameters. By using our algorithm, it is possible to estimate the temporal variations in cytoplasmic Ca2+ concentration and total Ca influx through cellular and endoplasmic reticulum (ER) membranes. doi:10.1016/j.neures.2009.09.330
P1-c04 Characterization of CREB phosphorylation induced by serotonin (5-HT) in cultured cortical neurons of mice Jiro Kasahara, Kohji Ohmura, Kohji Fukunaga Dept. Pharmacol., Grad. Sch. Pharmaceu. Sci., Tohoku Univ., Sendai, Japan Most of the antidepressants (ADs) have an inhibitory effect on monoamine transporters such as serotonin (5-HT) and/or noradrenaline transporters. In addition to this effect, long-term plastic changes of gene expressions are thought to be involved in the mechanisms of action of ADs. Combined together, monoaminetriggered signals may be transduced into nuclei of neurons, although its molecular and pharmacological properties are not well characterized yet. In this study, we characterized 5-HT-induced CREB phosphorylation in cultured cortical neurons derived from C57BL/6 mice. Compared to the strong and transient increase of glutamateinduced CREB phosphorylation, 5-HT induced weaker and prolonged increase of CREB phosphorylation. We further examined the protein kinases involved in its mechanism, and it was suggested that CaMKIV and MAPK were possible candidates. doi:10.1016/j.neures.2009.09.331
P1-c05 Modulation of feed-forward inhibition on CA1 pyramidal cells by patterned synaptic input probed with voltage-sensitive dye imaging in rat hippocampal slices Takashi Tominaga 1,2 , Yoko Tominaga 1 1
Dept. Neurophysiol., Tokushima Bunri Univ., Kagawa, Japan; Wako, Japan
2
RIKEN BSI,
Patterned input of inhibitory synapses on a cell plays an important role in neuronal function. However, inhibitory action is difficult to evaluate because of its multiple ways of regulation. Here we report an evaluation method of inhibitory action on membrane potential dynamics with voltage-sensitive dye (VSD) optical recording methods. Using this method we compared difference of laminar specific response upon stimulation to strata radiatum (SR), oriens (SO), and lacunosum-moleculare (SLM). The SR stimulation and SLM stimulation showed significant feed-forward components in perisomatic and distal apical dendritic regions. This was consistent with the IPSC components under whole cell clamp condition. We further evaluated modulation of the feed-forward inhibition by combination of temporal and combina-
S83
and integrity of PF synapses were lost. Although induction of motor memory of EBC requires intact PF synapses, retention and extinction of memories do not. These results support the view that the trace of motor memory is initially acquired in cerebellar cortex, and later transferred to different brain regions for consolidation.
P1-b31 Roles of Rabaptin-5 in AMPA receptor trafficking Kazuyuki Kiyosue, Kimihiko Kameyama
doi:10.1016/j.neures.2009.09.318
Recent studies reveal that AMPA receptors at postsynaptic membrane are constitutively cycled but kept in the number to mediate a constant synaptic response. Although AMPA receptor trafficking to endosome and from recycling endosome has reported to be critical steps for the expression of LTD and LTP, receptivity, there is no information about AMPA receptor trafficking from early endosome to recycling endosome. We focused on Rabaptin-5, because that molecule is a putative mediator molecule for receptor trafficking at the pathway. Analysis of Rabaptin-5 molecules by immunostainings revealed that Rabaptin-5 puncta were closely localized to postsynaptic densities. Over-expression of Rabaptin-5 promoted biased AMPA receptor trafficking. These results suggest that Rabaptin-5 has a role for selective receptor trafficking at postsynaptic sites.
P1-b28 Characterization of novel C1q family proteins in adult brain Eriko Miura 1,2 , Takatoshi Iijima 1 , Tetsuro Kondo 1,3 , Masahiko Watanabe 2 , Michisuke Yuzaki 1 1
Dept. Physiol., Keio Univ. Sch. of Med., Tokyo, Japan; 2 Dept. Anat., Hokkaido Univ. Sch. of Med., Hokkaido, Japan; 3 Mol. Neurophysiol, AIST, Tsukuba, Japan The C1q family proteins are involved in various intercellular processes, such as inflammation and cell differentiation. Although some C1q family members are expressed in the CNS, their functions have not been characterized well. Cbln1, a member of the Cbln subfamily of the C1q family, was recently shown to be released from granule cells and play crucial roles for synaptic integrity and plasticity in the cerebellum. Here we characterized the C1ql subfamily, composed of C1ql1-C1ql4. By in situ hybridization, each C1ql member had distinct spatial expression pattern outside the cerebellum. In addition, C1ql2 and C1ql3 mRNAs were coexpressed in the dentate gyrus of the hippocampus. Indeed, we found that all C1ql members were secreted and formed both homomer and heteromer each other. These results indicate that like Cbln, C1ql subfamily members may also serve as transneuronal regulators of synaptic functions in various brain regions. doi:10.1016/j.neures.2009.09.319
P1-b29 Acute administration of the neurosteroid DHEAS primes LTP induction in rat hippocampal slices via mGluR5 and cannabinoid 1 receptor Yuxia Xu 1 , Ling Chen 2 , Masahiro Sokabe 1,3 1
Dept. Physiol., Nogoya Univ., Grad. Sch. Med., Nagoya, Japan; 2 Dept. Physiol., Nanjing Med. Univ., Nanjing, China; 3 ICORP/SORST Cell Mechanosening, JST, Nagoya, Japan We have reported previously that chronic administration of DHEAS to adult rats facilitates LTP induction in the hippocampus (Chen et al., 2006), however, its process and mechanisms are unknown. To address these questions, the present study investigated the acute effects of DHEAS on rat hippocampal slices. A low dose of DHEAS (100 nM for 10 min) instantly caused a short term potentiation (STPDHEAS ) lasting for 30 min. Interestingly, after the termination of STPDHEAS , robust LTP could be induced by a sub-threshold tetanus of 20 pulses at 100 Hz, whereas 100 pulses at 100 Hz did not, which roughly resembles the chronic DHEAS effect. The facilitated LTP induction was inhibited by the antagonists of mGluR5 receptor and cannabinoid 1 receptor (CB1R), suggesting that DHEAS induces STPDHEAS , during which an mGluR5 and CB1R dependent priming mechanism for a following LTP induction has been established. doi:10.1016/j.neures.2009.09.320
P1-b30 Spine formation pattern of new neurons is modulated by induction of long-term potentiation (LTP) in adult dentate gyrus Noriaki Ohkawa 1,2 , Yoshito Saitoh 1,2 , Eri Tokunaga 1,2 , Toshio Kitamura 3 , Kaoru Inokuchi 1,2 1
Mitsubishi Kagaku Inst. Life Sci., Tokyo, Japan; Med. Sci., Univ. Tokyo, Tokyo, Japan
2
JST, CREST, Japan;
3
Inst.
In dentate gyrus of adult hippocampus, newborn neurons are functionally integrated into the existing circuits. It remains unclear whether the integration of new neurons into preexisting circuits is modulated by the acquisition of new information. We constructed a compatible system of retrovirus-mediated spine labeling of new neurons and in vivo LTP induction in dentate gyrus. LTP was induced at 12, 16 or 21 days postinfection (dpi) at which new neurons have no, few, or many spines, respectively, and spine expression pattern was observed at 28 dpi when sharp increment of the spine density is terminated. LTP induction at different dpi differentially regulated the density and size of spines on new neurons, suggesting that the acquisition of new information differentially regulates the integration of newly born neurons dependent on their developmental stages. Thus, new neurons at different stages may play different roles in processing the acquired information. doi:10.1016/j.neures.2009.09.321
National Institute of Advanced Industrial Science and Technology (AIST), Japan
doi:10.1016/j.neures.2009.09.322
P1-b32 Properties of quantal excitatory events in the central amygdala in neuropathic rats Yukari Takahashi 1 , Ayano Nakao-Iwase 1 , Ryo Ikeda 2 , Fusao Kato 1 1
Lab. Neurophysiol., Jikei Univ. Sch. Med., Tokyo, Japan; Jikei Univ. Sch. Med., Tokyo, Japan
2
Dept. Orthoped.,
The spino-parabrachio (PB)-amygdaloid pathway terminating in the laterocapsular part (CeLC) of the central amygdala plays an important role in the expression of pain-related negative emotion. The PB-CeLC synaptic transmission contralateral to the neuropathic side becomes potentiated without affecting paired-pulse ratio, leading to a hypothesis that postsynaptic mechanisms underlie this plasticity (Ikeda et al., 2007). To examine this, quantal events were recorded in the presence of Sr2+ . The asynchronous EPSCs from the potentiated side showed slightly but significantly larger amplitude, while the decay time constant was not significantly different. The average ratios of synchronous EPSC amplitude to asynchronous one were 55.5 and 23.0 in the potentiated and contralateral, respectively, CeLC. These data suggest increased number of synchronously released vesicles and a slight increase in postsynaptic AMPA receptor density underlie the synaptic potentiation by neuropathic pain. doi:10.1016/j.neures.2009.09.323
P1-b33 Proteolytic processing of protein-tyrosine phosphatase receptor type Z Akihiro Fujikawa 1 , Jeremy P.H. Chow 1,2 , Hidetada Shimizu 1 , Ryoko Suzuki 1 , Masaharu Noda 1,2 1
Div. Mol. Neurobio., NIBB, Okazaki, Japan; Stud., Okazaki, Japan
2
Sch. Life Sci., Grad. Univ. Adv.
Protein-tyrosine phosphatase receptor type Z (Ptprz) is preferentially expressed in the brain as a major chondroitin sulfate proteoglycan. Here, we show that the extracellular region of the receptor isoforms of Ptprz are cleaved by plasmin and metalloproteinases, and subsequently the membrane-tethered fragment is cleaved by gamma-secretase, releasing its intracellular region into the cytoplasm; of note, the intracellular fragment of Ptprz shows nuclear localization. The proteolytic processing of Ptprz by plasmin was markedly enhanced after kainic acid induced seizures in the mouse brain. Administration of GM6001, a metalloproteinase inhibitor, to mice demonstrated the metalloproteinase-mediated cleavage of Ptprz under physiological conditions. Furthermore, we mapped plasmin cleavage sites of Ptprz, and identified the cleavage sites by tumor necrosis factor-alpha converting enzyme (TACE) and matrix metalloproteinase 9. These findings indicate that Ptprz is a novel target for activity-dependent proteolytic processing in the central nervous system. doi:10.1016/j.neures.2009.09.324
P1-b34 Axon growth inhibition meadiated by p75-PIR-B receptor complex Yuki Fujita, Toshihide Yamashita Dept. Mol. Neurosci., Grad. Sch. Med., Osaka Univ., Osaka, Japan Myelin inhibitors, MAG, Nogo, OMgp inhibit axon regeneration. They bind to the same receptor, NgR. Recent study shows PIR-B is a second receptor for myelin inhibitors but its mechanism remains unclear. Our aim is to understand the molecular mechanism of axon growth inhibition mediated by PIR-B. Because p75 receptor is involved in the regulation of axon regeneration by myelin inhibitors, we investigate the interaction of p75 with PIR-B by co-immunoprecipitation. We also analyzed
S84
Abstracts
whether this interaction depends on the ligand binding to the receptor. In consequence, p75 interacts with PIR-B regardless of with or without MAG-Fc treatment in cerebellar glanule neurons. Downstream of this receptor complex, SHP is associated with the effector of MAG-Fc. Our results suggest that p75 associates with PIR-B to mediate the action of myelin-associated neurite growth inhibition. doi:10.1016/j.neures.2009.09.325
P1-b35 Diacylglycerol kinase  promotes dendritic outgrowth and spine maturation in developing hippocampal neurons Yasukazu Hozumi, Kaoru Goto Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan Diacylglycerol kinase (DGK) is involved in the intracellular signal transduction as a regulator of two second messengers, diacylglycerol and phosphatidic acid. Recently, we have reported that DGK is expressed in medium spiny neurons of the striatum and is highly concentrated at the perisynapse of dendritic spines. Furthermore, one of the transcripts derived from the human DGK locus is annotated in GenBank as being differentially expressed in bipolar disorder patients. However, it remains elusive how DGK is implicated in pathophysiological role in neurons at the cellular level. In the present study, we investigated a potential involvement of DGK in spine morphogenesis in transfected hippocampal neurons. We suggest that DGK is involved in the molecular machinery of dendrite outgrowth and spinogenesis through its kinase activity. doi:10.1016/j.neures.2009.09.326
P1-b36 Dendritic shape and EPSP conduction of cortical nonpyramidal cells Yoshiyuki Kubota 1 , Fuyuki Karube 1 , Masaki Nomura 2 , Toshio Aoyagi 2 , Yasuo Kawaguchi 1 1
Div. Cerebral Circuitry, NIPS, Okazaki, Japan; Informatics, Kyoto, Japan
2
Kyoto University Grad. Sch.
Dendritic morphology greatly influences neuronal synaptic signal integration. Dendritic arborization patterns and local dimensions were analyzed in four subtypes of neocortical GABAergic cells. The dendritic local size parameters were obtained by 3-dimensional reconstruction of serial ultrathin sections. The cross-sectional areas of dendrites were well correlated with the summated dendritic length between the measured point and end tips. At branch points, the cross-sectional area of the mother dendrite was almost equal to the sum of those of the two daughter branches. Following these morphological rules, we constructed computational model neurons and analyzed the passive conduction property of EPSP along the dendrite. The simulation studies revealed that the most synaptic excitatory inputs on various dendrite locations generate similar somatic depolarizations. These results suggest the 3-dimensional dendritic shape is formed to increase the equality among various excitatory inputs distributed along the dendrites. doi:10.1016/j.neures.2009.09.327
P1-c01 The effects of a novel anti-Parkisonian drug on dopamine syshesis and vesicular dopamine uptake in dopaminergic cells Taisuke Yamagiwa, Shintaro Yasui, Hiroko Inoue Graduate School of Advanced Science and Engineering, Waseda Univeersity, Tokyo, Japan An antiepileptic drug has recently been shown to exert beneficial effects in Parkinson’s disease. However, the mechanism of the anti-Parkinsonian effects of the drug remains unclear. In this study, we attempted to elucidate the effects of the antiepileptic drug on dopamine synthesis and vesicular dopamine storage in dopaminergic cells. We examined the effects of the drug on tyrosine hydroxylase (TH), the rate limiting enzyme in dopamine synthesis, in PC12 cells. The enzyme activity was increased by the treatment of the drug, although the expression level of TH was not altered. We also examined the effects of the drug on cytosolic dopamine uptake into secretory vesicles via vesicular monoamine transporter 2 in PC12 and SH-SY5Y cells. doi:10.1016/j.neures.2009.09.328
P1-c02 Regulation of alpha CaMKII-activation in living cells Kenichi Kato, Satoshi Kida Dep. of Bioscience, Tokyo Univ. of Agriculture, Tokyo, Japan
Increase in intracellular Ca2+ concentration has been shown to lead to the activation of ␣CaMKII thorough the interaction with Ca2+ /CaM (CaM-interaction) followed by the conformational change of this kinase. To understand the regulation of ␣CaMKII activity in vivo, we have investigated CaM-interaction and conformational change of ␣CaMKII in living cells using FRET. In this study, we compared dynamics of ␣CaMKII activation in several types of cells. In HeLa cells and SH-SY5Y cells, long-term increase in Ca2+ induced continuous CaM-interaction and conformational change of ␣CaMKII, while short-term increase induced only transient CaM-interaction but maintained the conformational change of ␣CaMKII even after the dissociation of CaM. Interestingly, we observed similar changes of CaM-interaction and conformational changes of ␣CaMKII in cortical neurons in response to long or short-term application, respectively, of NMDA. These findings suggest that differences of intracellular Ca2+ dynamics lead to distinct patterns of ␣CaMKII activation. doi:10.1016/j.neures.2009.09.329
P1-c03 Estimation of intracellular calcium ion concentration and Ca influx by nonlinear state space modeling Takamasa Tsunoda 1 , Toshiaki Omori 2,3 , Hiroyoshi Miyakawa 4 , Masato Okada 2,3 , Toru Aonishi 1,3 1
Tokyo Tech., Japan; 2 Univ. of Tokyo, Japan; Univ. of Pharm, Japan
3
RIKEN BSI, Japan;
4
Tokyo
Calcium imaging method has superior ability in recording of spatial-temporal variations of ion concentrations. However, it has two major problems. First, the imaging signals are too noisy. Second, the observation data are the fluorescent intensities of Ca2+ indicator dyes that are only indirect information about the Ca2+ concentration. We devised an algorithm based on a nonlinear state-space approach for estimating the Ca2+ concentration and the Ca influx from the noisy fluorescent signals. First, we made a state-space model for the fluorescent signal series including Ca kinetics and a noisy fluorescent intensity pickup process. Then, we derived recursive update equations for one-step-ahead prediction, filtering and smoothing, and devised an EM (Expectation Maximization) algorithm for determining the model parameters. By using our algorithm, it is possible to estimate the temporal variations in cytoplasmic Ca2+ concentration and total Ca influx through cellular and endoplasmic reticulum (ER) membranes. doi:10.1016/j.neures.2009.09.330
P1-c04 Characterization of CREB phosphorylation induced by serotonin (5-HT) in cultured cortical neurons of mice Jiro Kasahara, Kohji Ohmura, Kohji Fukunaga Dept. Pharmacol., Grad. Sch. Pharmaceu. Sci., Tohoku Univ., Sendai, Japan Most of the antidepressants (ADs) have an inhibitory effect on monoamine transporters such as serotonin (5-HT) and/or noradrenaline transporters. In addition to this effect, long-term plastic changes of gene expressions are thought to be involved in the mechanisms of action of ADs. Combined together, monoaminetriggered signals may be transduced into nuclei of neurons, although its molecular and pharmacological properties are not well characterized yet. In this study, we characterized 5-HT-induced CREB phosphorylation in cultured cortical neurons derived from C57BL/6 mice. Compared to the strong and transient increase of glutamateinduced CREB phosphorylation, 5-HT induced weaker and prolonged increase of CREB phosphorylation. We further examined the protein kinases involved in its mechanism, and it was suggested that CaMKIV and MAPK were possible candidates. doi:10.1016/j.neures.2009.09.331
P1-c05 Modulation of feed-forward inhibition on CA1 pyramidal cells by patterned synaptic input probed with voltage-sensitive dye imaging in rat hippocampal slices Takashi Tominaga 1,2 , Yoko Tominaga 1 1
Dept. Neurophysiol., Tokushima Bunri Univ., Kagawa, Japan; Wako, Japan
2
RIKEN BSI,
Patterned input of inhibitory synapses on a cell plays an important role in neuronal function. However, inhibitory action is difficult to evaluate because of its multiple ways of regulation. Here we report an evaluation method of inhibitory action on membrane potential dynamics with voltage-sensitive dye (VSD) optical recording methods. Using this method we compared difference of laminar specific response upon stimulation to strata radiatum (SR), oriens (SO), and lacunosum-moleculare (SLM). The SR stimulation and SLM stimulation showed significant feed-forward components in perisomatic and distal apical dendritic regions. This was consistent with the IPSC components under whole cell clamp condition. We further evaluated modulation of the feed-forward inhibition by combination of temporal and combina-