Vaccinia‐related kinase 2 (VRK2) is a serine/threonine kinase initially identified in highly prol... more Vaccinia‐related kinase 2 (VRK2) is a serine/threonine kinase initially identified in highly proliferative cells such as thymocytes and fetal liver cells, and it is involved in cell proliferation and survival. VRK2 is also expressed in the brain; however, its molecular function in the central nervous system is mostly unknown. Many genome‐wide association studies (GWASs) have reported that VRK2 is a potential candidate molecule for neuropsychiatric diseases such as schizophrenia in humans. However, the pathophysiological relationship between VRK2 and neuropsychiatric disorders has not been fully investigated. In this study, we evaluated vrk2‐deficient (vrk2−/−) zebrafish and found that vrk2−/− female zebrafish showed aggressive behavior and different social preference compared with control (vrk2+/+) zebrafish, with low gamma‐aminobutyric acid (GABA) content in the brain and high density of neuronal dendrites when compared to vrk2+/+ zebrafish. These findings suggest that female vrk2−...
and revealed a frequency-dependent auditory map in the primary auditory center. Here, we systemat... more and revealed a frequency-dependent auditory map in the primary auditory center. Here, we systematically characterized secondary auditory neurons, the AMMC-A1 and AMMC-B1 neurons, which feed into the highand lowfrequency zones in the primary auditory center, respectively. Histological analysis showed that the AMMC-A1 and AMMC-B1 neurons, both likely to transmit excitatory signals, send their contralateral projections to distinct regions in the ventral protocerebrum of the brain. The output synapses of the AMMC-A1 and the AMMC-B1 neurons, which were visualized by expressing a reporter protein, were distributed in each of these distinct regions, respectively. Together, these results indicate that the high-frequency AMMC-A1 pathway and the low-frequency AMMC-B1 pathway would remain segregated, by transmitting signals to distinct higher centers in the brain. The secondary auditory center in the fly would thus be comprised of at least two regions in the brain. Interestingly, the presynaptic sites of the AMMC-B1 neurons were also distributed in the primary auditory center. This result predicts that auditory system of the fruit fly would have feed-forward and feedback pathways, a characteristic shared with mammals. Research fund: The Grant-in-Aid for Young Scientists (B) from the JSPS, the Grant-in-Aid for Scientific Research on Innovative Areas “Systems Molecular Ethology” from the MEXT, PRESTO “Decoding and controlling brain information” from the JST, and the Mitsubisi Foundation.
Obesity is now a public health concern. The leading cause of obesity is an energy imbalance betwe... more Obesity is now a public health concern. The leading cause of obesity is an energy imbalance between ingested and expended calories. The mechanisms of feeding behavior and energy metabolism are regulated by a complex of various kinds of molecules, including anorexigenic and orexigenic neuropeptides. One of these neuropeptides, neuromedin U (NMU), was isolated in the 1980s, and its specific receptors, NMUR1 and NMUR2, were defined in 2000. A series of subsequent studies has revealed many of the physiological roles of the NMU system, including in feeding behavior, energy expenditure, stress responses, circadian rhythmicity, and inflammation. Particularly over the past decades, many reports have indicated that the NMU system plays an essential and direct role in regulating body weight, feeding behavior, energy metabolism, and insulin secretion, which are tightly linked to obesity pathophysiology. Furthermore, another ligand of NMU receptors, NMS (neuromedin S), was identified in 2005. N...
The TNF family molecule RANKL and its receptor RANK are key regulators of bone remodeling, lymph ... more The TNF family molecule RANKL and its receptor RANK are key regulators of bone remodeling, lymph node formation, and mammary gland development during pregnancy. RANKL and RANK are also expressed in the central nervous systems (CNS). However, the functional relevance of RANKL/RANK in the brain was entirely unknown. Recently, our group reported that the RANKL/RANK signaling pathway has an essential role in the central regulation of body temperature via the prostaglandin axis. This review discusses novel aspects of the RANKL/RANK system as key regulators of fever and female basal body temperature in the CNS.
The suprachiasmatic nucleus (SCN) is the master circadian clock in mammals and is properly entrai... more The suprachiasmatic nucleus (SCN) is the master circadian clock in mammals and is properly entrained by environmental light cycle. However, the molecular mechanism(s) determining the magnitude of phase shift by light is still not fully understood. The orphan G-protein-coupled receptor Gpr176 is enriched in the SCN, controls the pace (period) of the circadian rhythm in behavior but is not apparently involved in the light entrainment; Gpr176 / animals display a shortened circadian period in constant darkness but their phase-resetting responses to light are normal. Here, we performed microarray analysis and identified enhanced mRNA expression of neuromedin U (Nmu) and neuromedin S (Nms) in the SCN of Gpr176 / mice. By generating C57BL/6J-backcrossed Nmu/Nms/Gpr176 triple knockout mice, we noted that the mutant mice had a greater magnitude of phase shift in response to early subjective night light than wildtype mice, while Nmu/Nms double knockout mice as well as Gpr176 knockout mice are normal in the phase shifts induced by light. At the molecular level, Nmu / Nms / Gpr176 / mice had a reduced induction of Per1 and cFos mRNA expression in the SCN by light and mildly upregulated circadian expression of Per2, Prok2, Rgs16, and Rasl11b. These expressional changes may underlie the phenotype of the Nmu/Nms/Gpr176 knockout mice. Our data argue that there is a mechanism requiring Nmu, Nms, and Gpr176 for the proper modulation of lightinduced phase shift in mice. Simultaneous modulation of Nmu/Nms/Gpr176 may provide a potential target option for modulating the circadian clock.
Biochemical and Biophysical Research Communications, 2021
Cleavage factor polyribonucleotide kinase subunit 1 (CLP1), an RNA kinase, plays essential roles ... more Cleavage factor polyribonucleotide kinase subunit 1 (CLP1), an RNA kinase, plays essential roles in protein complexes involved in the 3'-end formation and polyadenylation of mRNA and the tRNA splicing endonuclease complex, which is involved in precursor tRNA splicing. The mutation R140H in human CLP1 causes pontocerebellar hypoplasia type 10 (PCH10), which is characterized by microcephaly and axonal peripheral neuropathy. Previously, we reported that RNA fragments derived from isoleucine pre-tRNA introns (Ile-introns) accumulate in fibroblasts of patients with PCH10. Therefore, it has been suggested that this intronic RNA fragment accumulation may trigger PCH10 onset. However, the molecular mechanism underlying PCH10 pathogenesis remains elusive. Thus, we generated knock-in mutant mice that harbored a CLP1 mutation consistent with R140H. As expected, these mice showed progressive loss of the upper motor neurons, resulting in impaired locomotor activity, although the phenotype was milder than that of the human variant. Mechanistically, we found that the R140H mutation causes intracellular accumulation of Ile-introns derived from isoleucine pre-tRNAs and 5' tRNA fragments derived from tyrosine pre-tRNAs, suggesting that these two types of RNA fragments were cooperatively or independently involved in the onset and progression of the disease. Taken together, the CLP1-R140H mouse model provided new insights into the pathogenesis of neurodegenerative diseases, such as PCH10, caused by genetic mutations in tRNA metabolism-related molecules.
Leucyl-tRNA synthetase (LARS) is an enzyme that catalyses the ligation of leucine with leucine tR... more Leucyl-tRNA synthetase (LARS) is an enzyme that catalyses the ligation of leucine with leucine tRNA. LARS is also essential to sensitize the intracellular leucine concentration to the mammalian target of rapamycin complex 1 (mTORC1) activation. Biallelic mutation in the LARS gene causes infantile liver failure syndrome type 1 (ILFS1), which is characterized by acute liver failure, anaemia, and neurological disorders, including microcephaly and seizures. However, the molecular mechanism underlying ILFS1 under LARS deficiency has been elusive. Here, we generated Lars deficient (larsb−/−) zebrafish that showed progressive liver failure and anaemia, resulting in early lethality within 12 days post fertilization. The atg5-morpholino knockdown and bafilomycin treatment partially improved the size of the liver and survival rate in larsb−/− zebrafish. These findings indicate the involvement of autophagy in the pathogenesis of larsb−/− zebrafish. Indeed, excessive autophagy activation was ob...
Vaccinia‐related kinase 2 (VRK2) is a serine/threonine kinase initially identified in highly prol... more Vaccinia‐related kinase 2 (VRK2) is a serine/threonine kinase initially identified in highly proliferative cells such as thymocytes and fetal liver cells, and it is involved in cell proliferation and survival. VRK2 is also expressed in the brain; however, its molecular function in the central nervous system is mostly unknown. Many genome‐wide association studies (GWASs) have reported that VRK2 is a potential candidate molecule for neuropsychiatric diseases such as schizophrenia in humans. However, the pathophysiological relationship between VRK2 and neuropsychiatric disorders has not been fully investigated. In this study, we evaluated vrk2‐deficient (vrk2−/−) zebrafish and found that vrk2−/− female zebrafish showed aggressive behavior and different social preference compared with control (vrk2+/+) zebrafish, with low gamma‐aminobutyric acid (GABA) content in the brain and high density of neuronal dendrites when compared to vrk2+/+ zebrafish. These findings suggest that female vrk2−...
and revealed a frequency-dependent auditory map in the primary auditory center. Here, we systemat... more and revealed a frequency-dependent auditory map in the primary auditory center. Here, we systematically characterized secondary auditory neurons, the AMMC-A1 and AMMC-B1 neurons, which feed into the highand lowfrequency zones in the primary auditory center, respectively. Histological analysis showed that the AMMC-A1 and AMMC-B1 neurons, both likely to transmit excitatory signals, send their contralateral projections to distinct regions in the ventral protocerebrum of the brain. The output synapses of the AMMC-A1 and the AMMC-B1 neurons, which were visualized by expressing a reporter protein, were distributed in each of these distinct regions, respectively. Together, these results indicate that the high-frequency AMMC-A1 pathway and the low-frequency AMMC-B1 pathway would remain segregated, by transmitting signals to distinct higher centers in the brain. The secondary auditory center in the fly would thus be comprised of at least two regions in the brain. Interestingly, the presynaptic sites of the AMMC-B1 neurons were also distributed in the primary auditory center. This result predicts that auditory system of the fruit fly would have feed-forward and feedback pathways, a characteristic shared with mammals. Research fund: The Grant-in-Aid for Young Scientists (B) from the JSPS, the Grant-in-Aid for Scientific Research on Innovative Areas “Systems Molecular Ethology” from the MEXT, PRESTO “Decoding and controlling brain information” from the JST, and the Mitsubisi Foundation.
Obesity is now a public health concern. The leading cause of obesity is an energy imbalance betwe... more Obesity is now a public health concern. The leading cause of obesity is an energy imbalance between ingested and expended calories. The mechanisms of feeding behavior and energy metabolism are regulated by a complex of various kinds of molecules, including anorexigenic and orexigenic neuropeptides. One of these neuropeptides, neuromedin U (NMU), was isolated in the 1980s, and its specific receptors, NMUR1 and NMUR2, were defined in 2000. A series of subsequent studies has revealed many of the physiological roles of the NMU system, including in feeding behavior, energy expenditure, stress responses, circadian rhythmicity, and inflammation. Particularly over the past decades, many reports have indicated that the NMU system plays an essential and direct role in regulating body weight, feeding behavior, energy metabolism, and insulin secretion, which are tightly linked to obesity pathophysiology. Furthermore, another ligand of NMU receptors, NMS (neuromedin S), was identified in 2005. N...
The TNF family molecule RANKL and its receptor RANK are key regulators of bone remodeling, lymph ... more The TNF family molecule RANKL and its receptor RANK are key regulators of bone remodeling, lymph node formation, and mammary gland development during pregnancy. RANKL and RANK are also expressed in the central nervous systems (CNS). However, the functional relevance of RANKL/RANK in the brain was entirely unknown. Recently, our group reported that the RANKL/RANK signaling pathway has an essential role in the central regulation of body temperature via the prostaglandin axis. This review discusses novel aspects of the RANKL/RANK system as key regulators of fever and female basal body temperature in the CNS.
The suprachiasmatic nucleus (SCN) is the master circadian clock in mammals and is properly entrai... more The suprachiasmatic nucleus (SCN) is the master circadian clock in mammals and is properly entrained by environmental light cycle. However, the molecular mechanism(s) determining the magnitude of phase shift by light is still not fully understood. The orphan G-protein-coupled receptor Gpr176 is enriched in the SCN, controls the pace (period) of the circadian rhythm in behavior but is not apparently involved in the light entrainment; Gpr176 / animals display a shortened circadian period in constant darkness but their phase-resetting responses to light are normal. Here, we performed microarray analysis and identified enhanced mRNA expression of neuromedin U (Nmu) and neuromedin S (Nms) in the SCN of Gpr176 / mice. By generating C57BL/6J-backcrossed Nmu/Nms/Gpr176 triple knockout mice, we noted that the mutant mice had a greater magnitude of phase shift in response to early subjective night light than wildtype mice, while Nmu/Nms double knockout mice as well as Gpr176 knockout mice are normal in the phase shifts induced by light. At the molecular level, Nmu / Nms / Gpr176 / mice had a reduced induction of Per1 and cFos mRNA expression in the SCN by light and mildly upregulated circadian expression of Per2, Prok2, Rgs16, and Rasl11b. These expressional changes may underlie the phenotype of the Nmu/Nms/Gpr176 knockout mice. Our data argue that there is a mechanism requiring Nmu, Nms, and Gpr176 for the proper modulation of lightinduced phase shift in mice. Simultaneous modulation of Nmu/Nms/Gpr176 may provide a potential target option for modulating the circadian clock.
Biochemical and Biophysical Research Communications, 2021
Cleavage factor polyribonucleotide kinase subunit 1 (CLP1), an RNA kinase, plays essential roles ... more Cleavage factor polyribonucleotide kinase subunit 1 (CLP1), an RNA kinase, plays essential roles in protein complexes involved in the 3'-end formation and polyadenylation of mRNA and the tRNA splicing endonuclease complex, which is involved in precursor tRNA splicing. The mutation R140H in human CLP1 causes pontocerebellar hypoplasia type 10 (PCH10), which is characterized by microcephaly and axonal peripheral neuropathy. Previously, we reported that RNA fragments derived from isoleucine pre-tRNA introns (Ile-introns) accumulate in fibroblasts of patients with PCH10. Therefore, it has been suggested that this intronic RNA fragment accumulation may trigger PCH10 onset. However, the molecular mechanism underlying PCH10 pathogenesis remains elusive. Thus, we generated knock-in mutant mice that harbored a CLP1 mutation consistent with R140H. As expected, these mice showed progressive loss of the upper motor neurons, resulting in impaired locomotor activity, although the phenotype was milder than that of the human variant. Mechanistically, we found that the R140H mutation causes intracellular accumulation of Ile-introns derived from isoleucine pre-tRNAs and 5' tRNA fragments derived from tyrosine pre-tRNAs, suggesting that these two types of RNA fragments were cooperatively or independently involved in the onset and progression of the disease. Taken together, the CLP1-R140H mouse model provided new insights into the pathogenesis of neurodegenerative diseases, such as PCH10, caused by genetic mutations in tRNA metabolism-related molecules.
Leucyl-tRNA synthetase (LARS) is an enzyme that catalyses the ligation of leucine with leucine tR... more Leucyl-tRNA synthetase (LARS) is an enzyme that catalyses the ligation of leucine with leucine tRNA. LARS is also essential to sensitize the intracellular leucine concentration to the mammalian target of rapamycin complex 1 (mTORC1) activation. Biallelic mutation in the LARS gene causes infantile liver failure syndrome type 1 (ILFS1), which is characterized by acute liver failure, anaemia, and neurological disorders, including microcephaly and seizures. However, the molecular mechanism underlying ILFS1 under LARS deficiency has been elusive. Here, we generated Lars deficient (larsb−/−) zebrafish that showed progressive liver failure and anaemia, resulting in early lethality within 12 days post fertilization. The atg5-morpholino knockdown and bafilomycin treatment partially improved the size of the liver and survival rate in larsb−/− zebrafish. These findings indicate the involvement of autophagy in the pathogenesis of larsb−/− zebrafish. Indeed, excessive autophagy activation was ob...
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Papers by Reiko Hanada