Journal of Oral Biosciences
Online ISSN : 1880-3865
Print ISSN : 1349-0079
ISSN-L : 1349-0079
52 巻, 4 号
選択された号の論文の14件中1~14を表示しています
REVIEW (JAOB/Rising Members Award)
  • Kimiko Saito, Kazuharu Nakagawa, Koichi Iwata
    2010 年 52 巻 4 号 p. 297-302
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    More than half of the inferior alveolar nerve (IAN) fibers were regenerated 14 days after IAN transection. The escape threshold following mechanical stimulation of the mental skin innervated by the transected IAN was significantly reduced but that of heat nocifensive behavior was not reduced at this time period, indicating that mechano-allodynia occurred but not heat hyperalgesia after IAN regeneration. Neuronal excitability of the myelinated primary afferent and trigeminal spinal subnucleus caudalis (Vc) neurons were significantly enhanced 14 days after IAN transection. However, heat evoked responses of primary afferent and Vc nociceptive neurons were not enhanced after IAN regeneration.
    These findings suggested that changes in excitability of the primary afferent and Vc nociceptive neurons were involved in mechano-allodynia but not in heat hyperalgesia in the cutaneous region innervated by the regenerated IAN.
REVIEW (Therapeutic Drugs to Treat the Bone Loss in the Periodontal Diseases)
  • Kazuhiro Aoki
    2010 年 52 巻 4 号 p. 303-310
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    The transcription factor nuclear factor-κB (NF-κB) plays a pivotal role in the regulation of the immune system, including the inflammatory response. The NF-κB signaling pathways also play an important role in bone homeostasis, especially in regard to osteoclast differentiation. The role of NF-κB in bone formation, however, remains to be fully elucidated. In this review, the effects of NF-κB inhibitors, focusing on bone formation, are described based on our findings.
  • Akira Nifuji, Hisashi Ideno, Rieko Takanabe, Masaki Noda
    2010 年 52 巻 4 号 p. 311-321
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Bone morphogenic proteins (BMP) are multifunctional growth factors and members of the TGF-β superfamily. They were identified based on their ability to initiate ectopic bone formation in non-skeletal tissue. To date, over 20 BMP family members have been identified and characterized as locally acting signal molecules. They function in development, differentiation, and disease in various tissues and species. BMP bind to typeI and typeII serine/threonine kinase BMP receptors, which phosphorylate intracellular Smad proteins. This triggers their translocation to the nucleus, where they activate the transcription of target genes.
    There are many BMP modulators which function at multiple levels: extracellular, membranous, and intracellular. Extracellular BMP modulators contain a cysteine-rich (CR) domain characterized by a conserved structural motif known as a cystine knot. They are classified according to the number of amino acids contained in the cystine-knot ring ; the three classes include the eight-, nine-, and ten-membered ring cystine knots. The proteins bind to various BMP ligands, block ligand-receptor binding, and inhibit BMP signaling. They also function as BMP activators in certain cellular and developmental contexts. The outcome of BMP regulatory function may differ depending on the differential binding capacities, temporal and spatial localization, and complexity of differential partnerships of BMP modulators. This review focuses on the versatile functions of the extracellular BMP modulators, particularly the CR domain-containing BMP-binding proteins in skeletal tissue.
REVIEW (Emergence of Oral Functions from the Activity of Receptor and Ion Channels)
  • —Roles for the Binding Partners—
    Takashi Kanematsu, Makoto Fujii, Hiroto Tanaka, Hisanori Umebayashi, M ...
    2010 年 52 巻 4 号 p. 322-329
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    The transmission of sensory information to the central nervous system during oral functions such as mastication and swallowing is well regulated by neural networks, including γ-aminobutyric acid (GABA)-mediated inhibitory interneurons. Therefore, an understanding of the mechanism of GABAergic transmission might provide new insight into the clinical treatment of eating and swallowing disorders. Type A GABA receptors are ligand-gated Cl- channels composed pentamerically of two α (1-6), two β (1-3), and one γ (1-3) subunit. One major issue regarding the efficacy of GABAergic transmission is how to control receptor numbers on neuronal surfaces, determining synaptic strength. The number of receptors on the postsynaptic membrane is maintained by a balance between receptor insertion and endocytosis. Insulin increases the number of GABAA receptors by stimulating insertion into the surface membrane via Akt-mediated phosphorylation of the β subunits. Conversely, brain-derived neurotrophic factor decreases the number by stimulating endocytosis. Here we show that PRIP (phospholipase C-related but catalytically inactive protein), isolated in our laboratory, actively participates in these two events by regulating the phosphorylation of β subunits and controlling the functions of binding partners such as Akt and protein phosphatases.
  • Youngnam Kang, Mitsuru Saito, Hiroki Toyoda, Hajime Sato
    2010 年 52 巻 4 号 p. 330-335
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    It is well established that motor units are recruited depending on the order of the size or input resistance of motoneurons, which is known as the size principle. During the slow-closing phase of the mastication cycle, the isometric contraction of jaw-closing muscles is developed through the recruitment of jaw-closing motoneurons. Two-pore-domain acid-sensitive K+ (TASK1/3) channels were recently found to be the molecular correlates of input resistance, and were also found to be expressed in the masseter motoneurons. Here, we discuss the possibility that spindle Ia inputs can induce the orderly recruitment of masseter motoneurons, and the possible involvements of TASK channels in the orderly recruitment.
  • Noriaki Koshikawa, Katsunori Tomiyama, John L. Waddington
    2010 年 52 巻 4 号 p. 336-343
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Elucidating the involvement of individual dopamine receptor subtypes in the regulation of orofacial movements has been made difficult by anomalies at the behavioral pharmacology-molecular biology interface; specifically, the extent to which gene cloning has revealed greater diversity in dopamine receptor typology beyond the original D1/D2 classification, to include individual members of D1-like (D1 and D5) and D2-like (D2, D3, and D4) families, has not been matched by similar progress in developing selective agonists and antagonists for these receptors. Although classical pharmacological approaches have been instrumental in defining dopamine-dependent behaviors at the family level, more incisive molecular genetic techniques are required to determine the functional roles of the individual members of these families; however, it is increasingly recognized that these molecular techniques have a number of inherent limitations. Furthermore, poorly understood methodological factors contribute to inconsistent phenotypic findings among laboratories. This review seeks to provide an overview of recent findings in dopamine receptor subtype knockouts across several orofacial movements and to interpret new insights in the context of the limitations of these techniques and prior knowledge of the regulation of behavior by dopamine receptors.
  • —The Central Effect of Acetylcholine on Drinking Behavior—
    Kiyotoshi Inenaga, Kentaro Ono
    2010 年 52 巻 4 号 p. 344-351
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Saliva is secreted from the salivary glands, and its production is controlled by the autonomic nervous system. Acetylcholine released by the parasympathetic nervous system stimulates muscarinic receptors and triggers the secretion of serous saliva. We found that intraperitoneally injected pilocarpine, which is known as a cholinergic muscarinic receptor agonist and a sialogue, increases not only saliva secretion but also drinking behavior in rats. This indicates that while pilocarpine increases wetness in the oral cavity, it also evokes the sensation of thirst and elicits water intake. Therefore, the thirst sensation can be evoked independently of oral wetness. Further, we found that nicotine, which is a stimulant of cholinergic nicotinic receptor, evokes the thirst sensation. We demonstrated that thirst was induced both by nicotine acting on nicotinic receptors in the brain and by pilocarpine acting on muscarinic receptors in the brain using behavioral, electrophysiological and molecular biological experiments. In this review, we discuss the relationship between oral dryness and thirst, and the different mechanisms underlying these two phenomena. We propose that while the symptom of xerostomia includes both oral dryness and thirst, it is important to understand that oral dryness and the sensation of thirst are intrinsically different.
  • Minoru Wakamori
    2010 年 52 巻 4 号 p. 352-357
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Membrane excitability is mainly regulated by ion channels, including both voltage-gated and ligand-gated channels. In addition to these conventional types of ion channel, a new class of ionic channel is also involved in regulation of the membrane potential. Transient receptor potential (TRP) channels are expressed not only in excitable cells, such as sensory organs, neurons, and cardiac myocytes, but also in non-excitable cells such as endothelial cells, B lymphocytes, and rat basophilic leukemia mast cells. Most TRP channels are Ca2+-permeable, and some are regulated by intracellular Ca2+. The aim of this review is to provide an overview of the TRP channel superfamily, and describe the electrophysiological properties and physiological roles of the neuronal Ca2+-sensitive non-selective cation channel TRPC5.
REVIEW (Front-line Researches by Young Oral Physiologists)
  • Ryusuke Yoshida, Mayu Niki, Yoshihiro Murata, Noriatsu Shigemura, Yuzo ...
    2010 年 52 巻 4 号 p. 358-364
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Gustatory information processing begins with taste bud cells, which are activated by sapid molecules via specific taste receptors and transmit their signals to gustatory afferent fibers. Taste bud cells are morphologically classified into 4 groups (Type I — IV cells), two of which are involved in gustatory sig-naling. Type II cells express sweet, bitter, and umami taste receptors and transduction components and respond best to sweet, bitter, or umami stimuli, suggesting that sweet, bitter, and umami tastes are detected by different sets of Type II cells. Type III cells express putative sour taste receptors and respond to sour or multiple taste stimuli, indicating that sour tastes are mediated by Type III cells. These data suggest that each taste quality could be discriminated among taste bud cells. Type II cells do not possess a conventional synaptic structure but they release ATP in response to taste stimuli. Type III cells have a synaptic structure and they release serotonin and norepinephrine but not ATP. Therefore, each taste cell may use distinct mechanisms and transmitters for signal transmission to gustatory nerve fibers.
  • Takashi Toda, Haruhide Hayashi
    2010 年 52 巻 4 号 p. 365-370
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    The first somatosensory cortex (SI) of primates is located in the postcentral gyrus of the parietal lobe. The orofacial structures are represented most laterally in SI. The inspection of neuronal properties there should lead to understanding of the neural basis that underlie dexterous orofacial functions, such as speech, mastication, manipulation of objects, and oral stereognosis. In the orofacial representation of SI, a substantial number of neurons have unique receptive fields (RFs) resulting from the spatiotemporal integration of converging somesthetic inputs. The relative incidences of those unique neurons increase on moving caudally from area 3 towards area 2. A neural process that binds spatiotemporal information arising from functionally-related portions might enable the brain to monitor the movement of objects in contact with orofacial structures or the kinematic trajectory of orofacial structures themselves. On the other hand, the modular organization of the neocortex is a widely documented concept, in which neural connectivity, composed of nearby cortical neurons, is considered to be the functional unit of integration. From this viewpoint, studies are needed to compare physiological properties among neurons localized in a small region of the orofacial representation. As for the RF extension, a small but substantial proportion of the pairs of nearby neurons are associated with discrete but functionally-related oral portions of different structures. As for the temporal aspects, a study is now underway in our laboratory to reveal the temporal relation between the activities of nearby neurons during sustained natural stimuli.
  • Yoshiyuki Shibukawa, Maki Tsumura, Masaki Sato, Hideki Ichikawa, Yasun ...
    2010 年 52 巻 4 号 p. 371-377
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Odontoblasts, well-polarized columnar cells at the periphery of the dental pulp, originate from neural crest cells. They are primarily involved in dentin formation (dentinogenesis) as sites of the synthesis and secretion of collagenous and non-collagenous matrix proteins, and also participate in the directional transport of Ca2+ from the circulation to the dentin-mineralizing front. Dentinogenesis is activated by: 1) pulpal patho-physiological events, such as intra-pulpal inflammatory responses, physiological or developmental processes, and 2) events at the dentin surface, such as various (mechanical/heat/cold) stimuli applied to the tooth surface. Therefore, the aim of this communication is to give an overview of the Ca2+-signaling system, which may have a major role in dentin formation in both physiological and pathological settings. Special attention will be given to discussion of the following: 1) sequential Ca2+ signaling pathways from internal inositol 1,4,5-trisphosphate (IP3) production via the activation of phospholipase C-coupled receptors to the release of Ca2+ from IP3-sensitive Ca2+ stores, 2) subsequent Ca2+ influx via store-operated Ca2+ channels, and 3) the expression of transient receptor potential channels coupled with Na+-Ca2+ exchangers in odontoblasts.
  • Masahiro Kondo, Koichi Iwata
    2010 年 52 巻 4 号 p. 378-387
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    The establishment of precise neuronal connectivity is the functional foundation of the brain, but details of its regulatory mechanism remain to be elucidated. Drosophila melanogaster Down syndrome cell adhesion molecule (Dscam) encodes a neuronal cell surface receptor in the immunoglobulin (Ig) superfamily. The mutually exclusive splicing of four variable exon clusters in the Dscam gene potentially generates 38,016 different Ig receptors. Each neuron expresses different sets of multiple Dscam isoforms, suggesting that each one has a unique cell surface identity. Dscam isoforms show robust trans-homophilic binding through ectodomains, which are diversified by a combination of three variable Ig domains. The homophilic interaction between Dscam isoforms on sister branches elicits repulsive responses. In contrast, the variable exon cluster encoding two transmembrane segments regulates the somatodendritic versus axonal localization of Dscam receptors. Dscam loss-of-function mutants show severe connectivity defects throughout the nervous system. The expression of a single Dscam isoform in a Dscam null clone restores axonal branch segregation and dendrite self-avoidance, but not precise axon targeting. Reducing Dscam ectodomain diversity in neurons causes connectivity defects. These findings provide evidence that the extensive molecular diversity and marked binding specificity of Dscam receptors play crucial roles in neural circuit formation.
REVIEW
  • Yasusei Kudo, Takaaki Tsunematsu, Takashi Takata
    2010 年 52 巻 4 号 p. 388-401
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Abnormal regulation of the cell cycle is essential for oncogenic transformation and tumor progression. The cell cycle is driven by the activity of the Cyclin/Cyclin-dependent kinase (Cdk) complex. Recently, the protein level of various cell cycle regulators including Cyclins and Cdk inhibitors was found to be regulated by the ubiquitin-proteasome pathway. In particular, SCF (Skp1-Cullin-F-box) and the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase complex play an important role in the ubiquitin-mediated proteolysis of cell cycle regulators. It has recently been revealed that the overexpression of oncogenic cell cycle regulators and reduced expression of tumor suppressive cell cycle regulators are caused by the abnormal regulation of ubiquitin-mediated proteolysis in cancer. In this review, we introduce the deregulation of APC/C ubiquitin ligase complex-dependent proteolysis in cancer.
ORIGINAL
  • Yoshitada Miyoshi, Makoto Watanabe, Nobuhiro Takahashi
    2010 年 52 巻 4 号 p. 402-408
    発行日: 2010年
    公開日: 2010/12/24
    ジャーナル 認証あり
    Proteolytic activity is reportedly present in saliva and seems to play a role in oral diseases such as periodontitis and dental caries. The present study aimed to investigate the autoactivation of proteolytic activity in whole saliva and its influence on salivary proteins. Whole saliva obtained from 10 healthy volunteers (mean age, 27.3±1.5 yr) by chewing paraffin displayed both gelatinolytic (1.21±0.52 unit/mL) and collagenolytic (0.05±0.02 unit/mL) activities using fluorescent-labeled substrates. These activities were partly inhibited by EDTA. Gelatinolytic and collagenolytic activities were significantly increased (p<0.01) in whole saliva by incubation at 37°C, and reached 5.6- and 8.8-times the original activities at 12 h, respectively. However, gelatinolytic activities in the supernatant or sediment of whole saliva showed no or low autoactivation. Gelatin zymography suggested that proteases in whole saliva mainly consisted of high-molecular-weight complex forms (>300 and 120 kDa) and a latent form (92 kDa) of matrix metalloproteinase-9 (MMP-9), and that these species were autoactivated at 37°C and truncated to a 42-kDa protein through 100-, 67-, and 50-kDa proteins. Moreover, SDS-PAGE analysis indicated that salivary proteins in whole saliva were gradually degraded and completely disappeared over 12 h. The present study revealed that whole saliva exhibits mainly gelatinolytic activity, which can be autoactivated in whole saliva and degrade salivary proteins.
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