Department of Pharmacology, Oita University, Faculty of Medicine

1-1 Idaigaoka, Hasamamachi, Oita, 879-5593, Japan

Phone; +81-97-586-5720

Fax; +81-97-586-5729

yakuri<at>oita-u.ac.jp

Staffs

Research Projects

Publication in English



Staffs
Professor :
  Toshimasa Ishizaki
Associate Professor :
  Toshihide Kimura
Assistant Professor :
  Takeshi Terabayashi
Visiting Researcher :
  Mami Yamaoka
Assistant :
  Kikumi Shimamura



Research Projects

Roles of the GDP-dependent Rab27a effector in membrane recycling in the pancreatic beta-cell

Small GTPases participate in a wide variety of cellular functions including proliferation, differentiation, adhesion, and intracellular transport. Conventionally, only the GTP-bound small GTPase interacts with effector proteins, and the resulting downstream signals control specific cellular functions. Therefore, the GTP-bound form is regarded as active, and the focus has been on searching for proteins that bind the GTP form to look for their effectors. The Rab family small GTPase Rab27a is highly expressed in pancreatic beta-cells and is involved in the control of membrane traffic. In the basal state, GTP-bound Rab27a controls insulin secretion at pre-exocytic stages via its GTP-dependent effectors. We previously identified novel GDP-bound Rab27-interacting proteins (coronin 3 and IQGAP1). Interestingly, GDP-bound Rab27a controls endocytosis of the secretory membrane via its interaction with these proteins. We also demonstrated that the insulin secretagogue glucose converts Rab27a from its GTP- to GDP-bound forms. Thus, GTP- and GDP-bound Rab27a regulate pre-exocytic and endocytic stages in membrane traffic, respectively. Since the physiological importance of GDP-bound GTPases has been largely overlooked, we consider that the investigation of GDP-dependent effectors for other GTPases is necessary for further understanding of cellular function.

  • Yamaoka M, Ando T, Terabayashi T, Okamoto M, Takei M, Nishioka T, Kaibuchi K, Matsunaga K, Ishizaki R, Izumi T, Niki I, Ishizaki T, Kimura T. PI3K regulates endocytosis after insulin secretion by mediating signaling crosstalk between Arf6 and Rab27a. J. Cell Sci. 129, 637-49, 2016
  • Yamaoka M, Ishizaki T, Kimura T. Interplay between Rab27a effectors in pancreatic beta-cells. World Journal of Diabetes, 6, 508-516, 2015
  • Yamaoka M, Ishizaki T, Kimura T. GTP- and GDP-dependent Rab27a effectors in pancreatic beta-cells. Biological and Pharmaceutical Bulletin, 38, 663-8, 2015
  • Kimura T, Yamaoka M, Taniguchi T, Okamoto M, Takei M, Ando T, Iwamatsu A, Watanabe T, Kaibuchi K, Ishizaki T, Niki I. Activated Cdc42-bound-IQGAP1 determines the cellular endocytic site. Molecular and Cellular Biology, 33, 4834-4843, 2013
  • Kimura T, Niki I. Rab27a in pancreatic beta-cells, a busy protein in membrane trafficking. Progress in Biophysics and Molecular Biology, 107, 219-223, 2011
  • Kimura T, Niki I. Rab27a, actin and beta-cell endocytosis. Endocr. J., 58, 1-6, 2011
  • Kimura T, Niki I. Rab GTPases control membrane recycling in pancreatic β-cell Beta Cells: Functions, Pathology and Research, Gallagher SE (ed.), Nova Biomedical, NY, 123-130, 2011
  • Kimura T, Taniguchi S, Toya K, Niki I. Glucose-induced translocation of coronin 3 regulates the retrograde transport of the secretory membrane in the pancreatic β-cells. Biochem. Biophys. Res. Commun., 395, 318-323, 2010
  • Kimura T, Taniguchi S, Niki I. Actin assembly controlled by GDP-Rab27a is essential for endocytosis of the insulin secretory membrane. Arch. Biochem. Biophys., 496, 33-37, 2010
  • Kimura T, Kaneko Y, Yamada S, Ishihara H, Senda T, Iwamatsu A, Niki I. The GDP-dependent Rab27a effector coronin 3 controls endocytosis of secretory membrane in insulin-secreting cell lines. J. Cell Sci., 121, 3092-3098, 2008

 


Studies on the effects of hydrogen sulfide on the beta cell functions.

Hydrogen sulfide (H2S) has been recognized to be a toxic gas produced in hot springs, mines, chemical plants and sewage treatment facilities. Recently, H2S was demonstrated to be generated intracellularly, and now expected to be the third gasotransmitter which mediates intra/intercellular signaling, such as NO or CO. We found that L-cysteine inhibited insulin secretion possibly via metabolic production of the gas. It is well known that diabetes mellitus and atherosclerosis are associated with a disorder in the metabolism of sulfur-containing amino acids including L-cysteine, and we therefore investigate the roles of H2S in the pathogeneses of these diseases.
  • Okamoto M, Ishizaki T, Kimura T (2015) Protective effect of hydrogen sulfide on pancreatic beta-cells. Nitric Oxide, 46, 32-36
  • Okamoto M, Yamaoka M, Takei M, Ando T, Taniguchi S, Ishii I, Tohya K, Ishizaki T, Niki I, Kimura T (2013) Endogenous hydrogen sulfide protects pancreatic beta-cells from a high-fat diet-induced glucotoxicity and prevents the development of type 2 diabetes. Biochem. Biophys. Res. Commun., 442, 227-233
  • Yamamoto J, Sato W, Kosugi T, Yamamoto T, Kimura T, Taniguchi S, Kojima H, Maruyama S, Imai E, Matsuo S, Yuzawa Y, Niki I (2013) Distribution of hydrogen sulfide (H2S)-producing enzymes and the roles of the H)S donor sodium hydrosulfide in diabetic nephropathy. Clin Exp Nephrol, 17, 32-40
  • Taniguchi S, Kimura T, Umeki T, Kimura Y, Kimura H, Ishii I, Itoh N, Naito Y, Yamamoto H, Niki I (2012) Protein phosphorylation involved in the gene expression of the hydrogen sulphide producing enzyme cystathionine γ-lyase in the pancreatic β-cell. Molecular and Cellular Endocrinology, 350, 31-38
  • Taniguchi S, Niki I (2011) Significance of hydrogen sulfide production in the pancreatic beta cell. J. Pharmacol. Sci., 116, 1-5
  • Taniguchi S, Kang L, Kimura T, Niki I (2011) Hydrogen sulphide protects mouse pancreatic β-cells from cell death induced by oxidative stress, but not by endoplasmic reticulum stress. Brit. J. Pharmacol., 162, 1171-1178
  • Kaneko Y, Kimura T, Taniguchi S, Souma M, Kojima Y, Kimura Y, Kimura H, Niki I (2009) Glucose-induced production of hydrogen sulfide may protect the pancreatic beta-cells from apoptotic cell death by high glucose. FEBS Letters, 583, 377-382.
  • Kaneko Y, Kimura Y, Kimura H, Niki I (2006) L-cysteine inhibits insulin release from the pancreatic β-cell; possible involvement of metabolic production of hydrogen sulfide, a novel gasotransmitter. Diabetes 55, 1391-1397.

 

 

 


Prevention of beta cell exhaustion in diabetic model animals and its application to the diabetic treatment.

Calmodulin, the most ubiquitous Ca2+-binding protein in the eukaryotes, used to be considered mainly to function in the pancreatic beta cell as a regulator of insulin secretion. However, beta cell-specific overexpression of calmodulin unexpectedly caused abrupt and massive disappearance of the beta cells and sudden-onset diabetes mellitus. We demonstrated that the decrease in the beta cell mass was due to Ca2+-influx into the beta cell and resultant production of NO. We proposed the transgenic mice is a model for the beta cell exhaustion. Moreover, we found that pituitary adenylate cyclase-activating polypeptides (PACAP), which increase the beta cell cAMP content, prevented the beta cell loss in this model. We expect this could be beneficial for the development of the treatment for type 2 diabetes mellitus. We have been also involved in the development of diabetic animal models which showed an impaired response to neural or hormonal regulation of insulin secretion. Using these models, we now study the pathogenesis and treatment of diabetes mellitus, as well as on the pathogenesis of the diabetic complications.
  • Yuzawa Y, Niki I, Kosugi T, Maruyama S, Yoshida F, Takeda M, Tagawa Y, Kaneko Y, Kimura T, Kato N, Yamamoto J, Sato W, Nakagawa T, Matsuo S (2008) Diabetic nephropathy in transgenic mice overexpressing beta cell calmodulin. J. Am. Soc. Nephrol., 19, 1701-1711
  • Tsunekawa S, Yamamoto Y, Tsukamoto K, Itoh Y, Kaneko Y, Kimura T, Ariyoshi Y, Miura Y, Oiso Y, Niki I (2007) Protection of pancreatic beta cells by exendin-4 may involve the reduction of endoplasmic reticulum stress; in vivo and in vitro studies. J. Endocrinol. 193, 65-74.
  • Tsunekawa S, Miura Y, Yamamoto N, Itoh Y, Ariyoshi Y, Senda T, Oiso Y, Niki I (2005) Systemic administration of pituitary adenylate cyclase-activating polypeptide maintains beta-cell mass and retards onset of hyperglycemia in beta cell-specific calmodulin-overexpressing transgenic mice. Eur. J. Endocrinol. 152, 805-811.
  • Horio F, Teradaira S, Imamura T, Anunciado RVP, Kobayashi M, Namikawa T, Niki I (2005) HND mouse, a non-obese model of type 2 diabetes with impaired insulin secretion, Eur J Endocrinnol 15, 971-979.
  • Yu W, Niwa T, Miura Y, Horio F, Teradaira S, Ribar TJ, Means AR, Hasegawa Y, Senda T, Niki I (2002) Calmodulin overexpression causes Ca2+-dependent apoptosis of pancreatic beta cells which can be prevented by inhibition of nitric oxide synthase. Lab Invest 82, 1229-1239.
  • oNiwa T, Nimura Y, Niki I (2001) Lack of effects of incretin hormones on insulin release from pancreatic islets in the bile duct-ligated rats. Am J Physiol 280, E59-E64.


Regulation of insulin secretion at pre-exocytotic stages.

After the synthesis of the insulin granules, multiple sequential steps are situated for these granules to be released to the extracellular space. We observed the behavior of the movement of the insulin granules in the cytoplasmic space of the living beta cell, and found that they are moving both directions possibly along the cytoskeleton. The movement was activated by intracellular Ca2+ mobilization or cAMP, but not by Ca2+ influx. Protein phosphorylation has been supposed to be an important mechanism by which a few second messengers control insulin secretion. We found that different protein kinases act on different steps in the secretory cascade, namely, protein kinase A and myosin light chain kinase on the granule movement and novel type protein kinase C on their docking to the plasma membrane.
  • Niki I, Niwa T, Yu W, Budzko D, Miki T, Senda T (2003) Ca2+-influx does not trigger glucose-induced traffic of the insulin granules and alteration of their distribution. Exp Biol Med 228, 1218-1226.
  • Niki I, Senda T (2002) Regulation of insulin release at pre-exocytotic stages of the secretory machinery. Current Medicinal Chemistry 2, 219-231
  • Niwa T, Fukasawa T, Yu W, Nimura Y, Senda T, Ohgawara H, Niki I (2001) Characterization of secretory and morphological properties of primary cultured endocrine cells from porcine pancreata. Pancreas 22, 135-40.
  • Yu W, Niwa T, Fukasawa T, Hidaka H, Senda T, Sasaki Y, Niki I (2000) Synergism of protein kinases A, C and myosin light chain kinase in the secretory cascade of the pancreatic beta-cell. Diabetes 49, 945-952.
  • Niki I (1999) Ca2+ signalling and secretory cascade in the pancreatic beta-cell. Jpn J Pharmacol 80, 191-197.
  • Niki I, Hisatomi M (1997) Analysis of the secretory granule movement in the pancreatic beta-cell : regulation by intracellular messengers. Jpn J Physiol 47, Suppl 1, S25-26.
  • Hisatomi M, Hayakawa T, Hidaka H, Niki I (1997) Modulation of Tyrosine kinase activity has multiple actions on insulin release from the pancreatic β-cell : Studies with lavendustin A. Jpn. J. Pharmacol., 74, 203-208.
  • Iida Y, Senda T, Matsukawa Y, Onoda K, Miyazaki J-I, Sakaguchi H, Nimura Y, Hidaka H, Niki I (1997) Myosin light chain phosphorylation controls insulin secretion at a proximal step in the secretory cascade. Am J Physiol 273, (Endocrinol. Metab. 36), E782-E789
  • Hisatomi M, Hidaka H, Niki I (1996) Ca2+/calmodulin and cAMP control movement of secretory granules through protein phosphorylation/dephosphorylation in the pancreatic β-cell. Endocrinology 137, 4644-4649.

Roles of Ca2+-binding proteins in insulin secretion.
Like most secreting cells or tissues, Ca2+ is the central intracellular messenger for insulin release. Nevertheless, not much is known about the processes which occur after a rise in intracellular Ca2+. We demonstrated that the S-100 protein calcyclin and annexin XI, a member of the annexin family were involved in the secretory machinery of the pancreatic beta cell. Furthermore, we suggested CaM kinase II and MLCK, both of which are activated in a Ca2+/calmodulin-dependent manner, play crucial roles in insulin release.
  • Iino S, Sudo T, Niwa T, Fukasawa T, Hidaka H, Niki I (2000) Annexin XI may be involved in Ca2+- or GTP-gS-induced insulin secretion in the pancreatic beta-cell. FEBS Lett 479, 46-50.
  • Niki I, Hidaka H (1999) Roles of Intracellular Ca2+ receptors in the pancreatic β-cell. Molec Cell Biochem 190, 119-124.
  • Niki I, Yokokura H, Sudo T, Kato M, Hidaka H (1996) Ca2+ signaling and intracellular Ca2+ binding proteins. (review) J. Biochem. (Tokyo), 120, 685-698.
  • Okazaki K, Niki I, Iino S, Kobayashi S, Hidaka H (1994) A role of calcyclin, a Ca2+-binding protein, on Ca2+-dependent insulin release in the pancreatic β cell. J Biol Chem 269, 6149-6152.
  • Niki I, Okazaki K, Saitoh M, Niki A, Niki H, Tamagawa T, Iguchi A, Hidaka H (1993) Presence and possible involvement of Ca/calmodulin-dependent protein kinases in insulin release from the rat pancreatic β cell. Biochem Biophys Res Commun 191 : 255-261.


Molecular imaging of a malignant tumor.

Recent progress in diagnostic imaging enables us to detect certain diseases in an early stage, which used to be difficult. We attempt scintigraphic imaging of malignant cancer in vivo using radioisotopically-labelled and tumor-specific monoclonal antibody as a tracer.

  • Matsumura K, Niki I, Tian H, Takuma M, Hongo N, Matsumoto S,Mori M (2008) Radioimmunoscintigraphy of pancreatic cancer in tumor-bearing athymic nude mice using 99mtechnetium-labeled anti-KL-6/MUC1 antibody. Radiation Medicine, 26, 133-139

 




Publication in English
  • Okamoto M, Yamaoka M, Takei M, Ando T, Taniguchi S, Ishii I, Tohya K, Ishizaki T, Niki I, Kimura T (2013) Endogenous hydrogen sulfide protects pancreatic beta-cells from a high-fat diet-induced glucotoxicity and prevents the development of type 2 diabetes. Biochem. Biophys. Res. Commun., 442, 227-233
  • Kimura T, Yamaoka M, Taniguchi T, Okamoto M, Takei M, Ando T, Iwamatsu A, Watanabe T, Kaibuchi K, Ishizaki T, Niki I (2013) Activated Cdc42-bound-IQGAP1 determines the cellular endocytic site. Molecular and Cellular Biology, 33, 4834-4843
  • Yamamoto J, Sato W, Kosugi T, Yamamoto T, Kimura T, Taniguchi S, Kojima H, Maruyama S, Imai E, Matsuo S, Yuzawa Y, Niki I (2013) Distribution of hydrogen sulfide (H2S)-producing enzymes and the roles of the H2S donor sodium hydrosulfide in diabetic nephropathy. Clin Exp Nephrol. 17, 32-40
  • Taniguchi S, Kimura T, Umeki T, Kimura Y, Kimura H, Ishii I, Itoh N, Naito Y, Yamamoto H, Niki I (2012) Protein phosphorylation involved in the gene expression of the hydrogen sulphide producing enzyme cystathionine γ-lyase in the pancreatic β-cell. Molecular and Cellular Endocrinology, 350, 31-38
  • Kimura T, Niki I (2011) Rab27a in pancreatic beta-cells, a busy protein in membrane trafficking. Progress in Biophysics and Molecular Biology, 107, 219-223
  • Taniguchi S, Niki I (2011) Significance of hydrogen sulfide production in the pancreatic beta cell. J. Pharmacol. Sci., 116, 1-5
  • Kimura T, Niki I (2011) Rab27a, actin and beta-cell endocytosis. Endocr. J., 58, 1-6
  • Taniguchi S, Kang L, Kimura T, Niki I (2011) Hydrogen sulphide protects mouse pancreatic β-cells from cell death induced by oxidative stress, but not by endoplasmic reticulum stress. Brit. J. Pharmacol., 162, 1171-1178
  • Kimura T, Niki I. (2011) Rab GTPases control membrane recycling in pancreatic β-cells. Beta Cells: Functions, Pathology and Research, Gallagher SE (ed.), Nova Biomedical, NY, 123-130
  • Kimura T, Taniguchi S, Toya K, Niki I (2010) Glucose-induced translocation of coronin 3 regulates the retrograde transport of the secretory membrane in the pancreatic β-cells. Biochem. Biophys. Res. Commun., 395, 318-323
  • Kimura T, Taniguchi S, Niki I (2010) Actin assembly controlled by GDP-Rab27a is essential for endocytosis of the insulin secretory membrane. Arch. Biochem. Biophys., 496, 33-37
  • Okamoto T, Kanemoto N, Ban T, Sudo T, Nagano K, Niki I (2009) Establishment and characterization of a novel method for evaluating gluconeogenesis using hepatic cell lines, H4IIE and HepG2. Arch. Biochem. Biophys., 491, 46-52
  • Arimura N, Hattori A, Kimura T, Nakamuta S, Funahashi Y, HirotsuneS, Furuta K, UranoT, Toyoshima Y, Kaibuchi K (2009) CRMP-2 directly binds to cytoplasmic dynein and interferes with its activity. J Neurochem., in press
  • Arimura N, Kimura T, Nakamuta S, Taya S, Funahashi Y, Hattori A, Shimada A., Menager C., Kawabata S, Fujii K, Iwamatsu A, Segal RA, Fukuda M, Kaibuchi K (2009) Direct interaction of Slp1 and Rab27 with TrkB receptor regulates its anterograde transport in axons. Dev. Cell, 16, 675-686
  • Kaneko Y, Kimura T, Taniguchi S, Souma M, Kojima Y, Kimura Y, Kimura H, Niki I (2009) Glucose-induced production of hydrogen sulfide may protect the pancreatic beta-cells from apoptotic cell death by high glucose. FEBS Letters, 583, 377-382
  • Kimura T, Kaneko Y, Yamada S, Ishihara H, Senda T, Iwamatsu A, Niki I (2008) The GDP-dependent Rab27a effector coronin 3 controls endocytosis of secretory membrane in insulin-secreting cell lines. J. Cell Sci., 121, 3092-3098
  • Yuzawa Y, Niki I, Kosugi T, Maruyama S, Yoshida F, Takeda M, Tagawa Y, Kaneko Y, Kimura T, Kato N, Yamamoto J, Sato W, Nakagawa T, Matsuo S (2008) Diabetic nephropathy in transgenic mice overexpressing beta cell calmodulin. J. Am. Soc. Nephrol., 19, 1701-1711
  • Matsumura K, Niki I, Tian H, Takuma M, Hongo N, Matsumoto S,Mori M (2008) Radioimmunoscintigraphy of pancreatic cancer in tumor-bearing athymic nude mice using 99mtechnetium-labeled anti-KL-6/MUC1 antibody. Radiation Medicine, 26, 133-139
  • Tsunekawa S, Yamamoto Y, Tsukamoto K, Itoh Y, Kaneko Y, Kimura T, Ariyoshi Y, Miura Y, Oiso Y, Niki I (2007) Protection of pancreatic beta cells by exendin-4 may involve the reduction of endoplasmic reticulum stress; in vivo and in vitro studies. J. Endocrinol. 193, 65-74.
  • Kaneko Y, Kimura Y, Kimura H, Niki I (2006) L-cysteine inhibits insulin release from the pancreatic β-cell; possible involvement of metabolic production of hydrogen sulfide, a novel gasotransmitter. Diabetes 55, 1391-1397.
  • Takii M, Ishikawa T, Tsuda H, Kanatani K, Sunouchi T, Kaneko Y,Nakayama K (2006) Involvement of stretch-activated cation channels in hypotonically induced insulin secretion in rat pancreatic β-cells. Am J Physiol Cell Physiol, in press
  • Tsunekawa S, Miura Y, Yamamoto N, Itoh Y, Ariyoshi Y, Senda T, Oiso Y, Niki I (2005) Systemic administration of pituitary adenylate cyclase-activating polypeptide maintains beta-cell mass and retards onset of hyperglycemia in beta cell-specific calmodulin-overexpressing transgenic mice. Eur. J. Endocrinol. 152, 805-811.
  • Kimura T, Arimura N, Fukata Y, Watanabe H, Iwamatsu A, Kaibuchi K (2005). Tubulin and CRMP-2 complex is transported via Kinesin-1 J Neurochem. 93, 1371-82
  • Ishikawa T, Iwasaki E, Kanatani K, Sugino F, Kaneko Y, Obara K, Nakayama K (2005) Involvement of novel protein kinase C isoforms in carbachol-stimulated insulin secretion from rat pancreatic islets. Life Sciences 77, 462-469.
  • Horio F, Teradaira S, Imamura T, Anunciado RVP, Kobayashi M, Namikawa T, Niki I (2005) HND mouse, a non-obese model of type 2 diabetes with impaired insulin secretion, Eur J Endocrinol 153, 971-979.
  • Niki I, Niwa T, Yu W, Budzko D, Miki T, Senda T (2003) Ca2+-influx does not trigger glucose-induced traffic of the insulin granules and alteration of their distribution. Exp Biol Med 228, 1218-1226.
  • Kaneko Y, Ishikawa T, Amano S, Nakayama K (2003) Dual effect of nitric oxide on cytosolic Ca2+ concentration and insulin secretion in rat pancreatic β-cells. Am J Physiol Cell Physiol 284: C1215-C1222
  • Ishikawa T, Kaneko Y, Sugino F, Nakayama K (2003) Two distinct effects of cGMP on cytosolic Ca2+ concentration of rat pancreatic β-cells. J Pharmacol Sci 91: 41-46
  • Nakada S, Ishikawa T, Yamamoto Y, Kaneko Y, Nakayama K (2003) Constitutive nitric oxide synthases in rat pancreatic islets: direct imaging of glucose-induced nitric oxide production in β-cells. Pflugers Arch-Eur J Physiol 447: 305-311
  • Niki I, Senda T (2002) Regulation of insulin release at pre-exocytotic stages of the secretory machinery. Current Medicinal Chemistry 2, 219-231
  • Yu W, Niwa T, Miura Y, Horio F, Teradaira S, Ribar TJ, Means AR, Hasegawa Y, Senda T, Niki, I (2002) Calmodulin overexpression causes Ca2+-dependent apoptosis of pancreatic beta cells which can be prevented by inhibition of nitric oxide synthase. Lab Invest 82, 1229-1239.
  • Sugino F, Ishikawa T, Nakada S, Kaneko Y, Yamamoto Y, Nakayama K (2002) Inhibition by nitric oxide of Ca2+ responses in rat pancreatic α-cells. Life Sciences 71: 81-89
  • Fukata Y, Kimura T, Kaibuchi K. Axon Specification in Hippocampal (2002) Neurons Neuroscience Research 43, 305-15
  • Fukata Y, Itoh TJ, Kimura T, Menager C, Nishimura T, Shiromizu T, Watanabe H, Inagaki N, Iwamatsu A, Hotani H, Kaibuchi K (2002) CRMP-2 binds to tubulin heterodimers to promote microtubule assembly ; a possible mechanism for CRMP-2 mediated axonal growth. Nature Cell Biology 4, 583-91


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