\u3000Many organisms, including humans, utilize D-glucose as their primary energy source for life activities. Since cancer cells also consume it in large quantities, it is widely used in PET scans for cancer detection. However, PET scans have difficulty detecting tumors until they reach approximately 5 mm in size. Therefore, extensive research is being conducted to visualize single cancer cells by utilizing the property of 2-NBDG\u2014a fluorescently labeled form of D-glucose (Yamada, K. et al., Nature Protocols<\/i> 2007)\u2014to be taken up by cancer cells. Nevertheless, because D-glucose is also taken up by benign tumors, inflammation, and normal cells (especially in the brain), the accurate and early detection of particularly small malignant tumors (= cancer) remains challenging.<\/span><\/p>\r\n \u3000In response to this challenge, in 2010, we developed 2-NBDLG as the world’s first fluorescently labeled form of L-glucose (the enantiomer of D-glucose), which had previously been overlooked as a sugar not utilized by living organisms (Rudney, H., Science<\/i> 1940). We discovered that 2-NBDLG is taken up via a selective mechanism into pancreatic tumor cells that exhibit strongly malignant characteristics, and we have since acquired over 40 patents. It is gradually becoming clear that this trait is applicable to a wide range of cancer types and is not limited to fluorescently labeled L-glucose, but rather stems from the inherent properties of L-glucose itself. Furthermore, by applying anticancer drugs that use L-glucose as a drug delivery system to cancer cells detected with L-glucose probes, we are advancing the development of cancer-cell-selective diagnostic and therapeutic technologies that minimize side effects on normal cells.<\/span><\/p>\r\n<\/div>\r\n \r\n\r\n<\/p>\r\n Profile<\/p>\r\n \r\n\r\n<\/p>\r\n Dr. Katsuya Yamada, PhD.<\/strong><\/span><\/p>\r\n\r\n\r\n\r\n \u3000After completing his PhD program in Neurophysiology from Kyoto Prefectural University School of Medicine in 1992, Katsuya Yamada was appointed to Assistant Professor at Akita University. With Dr. Nobuhiko Yamamoto (Osaka University, currently) and Prof. Keisuke Toyama, he developed a cortico-cortical, and cortico-superior collicular slice co-culture systems, which enabled intracellular recordings of in vitro changes in monosynaptic transmission from cortical cells in various layers, later proven to be reflecting developmental changes in NMDA component (Yamamoto, Yamada, Kurotani and Toyama, Neuron 9: 217-228, 1992; Yamada, Yamamoto and Toyama, Eur. J. Neurosci. 12: 3854-3862, 2000).<\/span><\/p>\r\n\r\n\r\n<\/span>\r\n \u3000In 2000, with Prof. Nobuya Inagaki (Kyoto University, currently) and Prof. Hideaki Matsuoka (Tokyo University of Agriculture and Technology), he demonstrated that a fluorescent D-glucose analogue 2-NBDG, which was invented by Matsuoka to see viability of E-coli cells, is taken up into mammalian cells through GLUTs in a quantitative manner (Yamada et al., J. Biol. Chem. 2000). Later on, 2-NBDG has been effectively used in various studies as a standard tool for visualizing glucose uptake (see such as Yamada et al., Nature Protocols 2: 753-762, 2007). To precisely evaluating possible adsorption and non-specific uptake of 2-NBDG, Dr. Yamada developed 2-NBDLG as a control substrate, the first fluorescent analogue of L-glucose available with Dr. Toshihiro Yamamoto (Patents: Yamada et al, EP2325327B1, US8986656B2, JP5682881; Yamamoto, et al., Tetrahedron Lett. 49: 6876-6878, 2008). Unexpectedly, Yamada found with Dr. Ayako Sasaki (PhD student at that time) that 2-NBDLG is taken up into three dimensionally accumulated insulinoma cells showing nuclear heterogeneity, leading to later projects supported by JST, AMED, and Hirosaki University Institutional Research for developing cancer diagnostics.<\/span><\/p>\r\n\r\n\r\n<\/span>\r\n \u3000In late 1990\u2019s, Dr. Yamada started his research with Prof. Inagaki in midbrain nucleus substantia nigra pars reticulata (SNr), the area with the highest expression of ATP-sensitive potassium (KATP) channels in the brain, soon discovering the role of KATP channel during metabolic stress, focusing on its involvement in a suppression mechanism of energy-consuming seizure propagation (Yamada et al, Science 292: 1543-1546, 2001; Yamada and Inagaki, J. Mol. Cell. Cardiol. 38: 945-949, 2005) and gasping (Miyake et al, Eur. J. Neurosci. 25: 2349-2363, 2007). With Dr. Hongjie Yuan (PhD student at that time, Assistant Prof. in Emory Univ. currently), he also discovered that SNr GABAergic neurons sense lowering of glucose (Yuan et al., Neurosci. Lett. 355: 173-176, 2004). These neurons also exhibited multi-minutes oscillation (Yuan et al., Neurosci. Lett. 355: 136-140, 2004), leading to later findings of brain area-specific dopamine receptor expressions in thin astrocytic process and glycine release from astrocytes in response to dopamine collaborating with Dr. Katsuhiro Nagatomo (postdoc initially, then Assistant Prof in Yamada Lab; Nagatomo et al, Front. Neuroanat. 11: 2017) and Dr. Koji Shibasaki (Associate Prof. in Gunma Univ. at that time, Prof. in University of Nagasaki currently. Shibasaki, et al., J. Neurochem. 140: 395-403, 2017), respectively.<\/span><\/p>\r\n\r\n\r\n<\/span>\r\n \u3000In 2005, he moved to Hirosaki city, became an Associate Professor in the Department of Physiology at Hirosaki University Graduate School of Medicine, where he has been continuing with his research since.<\/span><\/p>\r\n<\/div>\r\n<\/div>\r\n \r\n\r\n<\/p>\r\n Ongoing Project<\/p>\r\n \r\n\r\n<\/p>\r\n Imaging Glucose Uptake into Cells by Fluorescent Glucose Analogues<\/strong><\/span><\/p>\r\n Background<\/strong><\/span> Research Results<\/strong><\/span> Future Prospects<\/strong><\/span> <\/p>\r\n <\/p>\r\n Neurotransmitter-induced Gliotransmitter Release and Glial Heterogeneity<\/span><\/strong><\/p>\r\n Background<\/strong><\/span> Research Results<\/strong><\/span> Double immunolabeling of SNr cells acutely dissociated from adult wild-type mice brain further revealed marked D1R immunoreactivity in the processes of glial fibrillary acidic protein (GFAP)-positive astrocytes. Such D1R imunoreactivity was significantly stronger in the SNr astrocytes than that in those of the visual cortex.<\/span> Fu<\/strong><\/span>ture <\/strong><\/span>Prospects<\/strong><\/p>\r\n \u3000A<\/span><\/span>lthough matured astrocytes may differ from the cultured astrocytes, it is interesting to speculate that dendri<\/span><\/span>tically released neurotransmitter dopamine can regulate neuronal activity via gliotransmitter glycine release from astrocytes in the SNr. The divergent expression of D1 receptor on astrocytes in SNr, striatum, and cortex implies astrocyte heterogeneity. Further studies are required to elucidate the functional role of dopamine receptors in astrocytes. In addition, it may be interesting to speculate relationships between glycine release from astrocytes and extrasynaptic regulation of NMDA receptors.<\/span><\/p>\r\n <\/p>","protected":false},"excerpt":{"rendered":"![\"\"](\"https:\/\/home.hirosaki-u.ac.jp\/transport\/wp-content\/uploads\/sites\/130\/yamada150226E-2.jpg\")
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\u3000Most living things take up and metabolize naturally occurring D-glucose as essential fuel. By contrast, little is known about use of its mirror image isomer L-glucose. Mammalian cells take up D-glucose through glucose transporters such as GLUTs. A green fluorescence-emitting D-glucose analogue 2-NBDG can visualize this process at the single cell level. For obtaining a precise control substrate for 2-NBDG, we developed 2-NBDLG, the first fluorescent analogue of L-glucose (fLG).<\/span>![\"\"](\"http:\/\/home.hirosaki-u.ac.jp\/transport\/wp-content\/uploads\/sites\/130\/research1-1-300x77.png\")
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\u3000Most living things take up and metabolize naturally occurring D-glucose as essential fuel. By contrast, little is known about use of its mirror image isomer L-glucose. Mammalian cells take up D-glucose through glucose transporters such as GLUTs. A green fluorescence-emitting D-glucose analogue 2-NBDG can visualize this process at the single cell level. For obtaining a precise control substrate for 2-NBDG, we developed 2-NBDLG, the first fluorescent analogue of L-glucose (fLG).<\/span><\/p>\r\n![\"\"](\"http:\/\/home.hirosaki-u.ac.jp\/transport\/wp-content\/uploads\/sites\/130\/research2-300x211.png\")
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\u3000This method will facilitate accurate diagnosis and necessary and sufficient removal of lesions that have potential of developing cancer while sparing normal functions as much as possible. Use of the method as a drug delivery system is a potential as well. We would like to proceed with students and colleagues who believe that \u201cFreedom to pursuit things what \u2018you\u2019 think important\u201d may open a new door towards future.<\/span><\/span><\/p>\r\n
\u3000Substantia nigra pars reticulata (SNr), the major output nucleus of the basal ganglia, consists mostly of GABAergic projection neurons showing highest spontaneous firing activity in the brain. We have shown the role of ATP-sensitive potassium (KATP) channel during metabolic stress, focusing on its involvement in a suppression mechanism of energy-consuming seizure propagation.<\/span><\/span>
\u3000SNr receives dopamine from dendrites (dendritic release) extending from dopaminergic neurons of the adjacent nucleus pars compacta (SNc), which is known for its selective degeneration in Parkinson\u2019s disease. Whereas, the significance of dopamine released from nigrostriatal axons has been extensively studied, much less attention has been paid to dopamine dendritically released in the SNr, in particular to the cellular entity expressing dopamine receptors.<\/span>
\u3000As a recipient for the released dopamine, the dopamine D1 receptor (D1R) is a primary candidate due to its very dense immunoreactivity in the SNr (Collaboration with Prof. Yoshio Yamamoto, Iwate Univ.). However, the precise location of D1R remains unclear at the cellular level in the SNr except for that reported on axons\/axon terminals.<\/span>
\u3000Over 30 years ago, Reubi and Sandri reported in electronmicroscopic\/freeze etching studies that nigral dendrites fail to form dendro-dendritic contacts in the SNr, but are consistently separated by one or two thin glial sheaths. Interestingly, Bosson and colleagues reported that acute interruption of dopaminergic transmission increased astrocyte synchrony in the SNr. These studies suggest that astrocytes might well participate in dopamine transmission.<\/span><\/p>\r\n![\"\"](\"http:\/\/home.hirosaki-u.ac.jp\/transport\/wp-content\/uploads\/sites\/130\/research3-300x208.png\")
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\u3000Dr. Katsuhiro Nagatomo in our lab addressed this issue using D1R promotor-controlled, mVenus-expressing transgenic mice (kindly provided by Prof. Kazuto Kobayashi, Fukushima Medical Univ.). When cells were acutely dissociated from SNr of the mouse brain, prominent mVenus fluorescence was detected in fine processes of glia-like cells, whereas no such fluorescence was detected from neurons except for the synaptic bouton-like structures.<\/span><\/span><\/p>\r\n
\u3000Interestingly, GFAP-positive astrocytes dissociated from the striatum demonstrated D1R immunoreactivity, either remarkable or minimal, similarly to that shown in neurons in this nucleus. In contrast, in the SNr and visual cortex, only weak D1R immunoreactivity was detected in the neurons tested.<\/span>
\u3000These results suggest that the SNr astrocyte may be a candidate recipient for dendritically released dopamine. In addition, we speculate that astrocytes may have divergent dopamine receptor expression profiles in a brain area-specific manner.<\/span>
\u3000Astrocytes play important roles in the regulation of neuronal transmission. Previously, we found with Dr. Hongjie Yuan (PhD student at that time, Assistant Prof. in Emory Univ. currently) that spontaneous firing rate of SNr GABAergic neurons increased in response to moderately lowering of extracellular glucose concentration). These neurons also exhibited multi-minutes oscillation. When conducting the latter study, we obtained data showing that glycine may participate in the regulation of neuron activity in the SNr. However, there was no study reporting glycinergic axon terminal in the SNr.<\/span>
\u3000Collaborating with Dr. Koji Shibasaki (Associate Prof. in Gunma Univ.) and Prof. Makoto Tominaga (Okazaki Institute), we addressed this issue by conducting amino acid analyses and a patch clamp biosensor method, reporting that neurotransmitter dopamine causes glycine release from cultured cortical astrocytes by functional reversal of glycine transporter 1, an astrocytic type of glycine transporter.<\/span><\/sup>
<\/sup><\/span><\/span><\/p>\r\n![\"\"](\"http:\/\/home.hirosaki-u.ac.jp\/transport\/wp-content\/uploads\/sites\/130\/research4.png\")
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