論文 - 吉村　昭彦

CDK inhibitors suppress Th17 and promote iTreg differentiation, and ameliorate experimental autoimmune encephalomyelitis in mice

Yoshida Hideyuki, Kotani Hitoshi, Kondo Taisuke, Tani Ito, Wei Xuetao, Tsuruta Sanae, Kimura Akihiro, Asakawa Mayako, Ito Minako, Nagai Shigenori, Yoshimura Akihiko

Biochemical and Biophysical Research Communications 435 （ 3 ） 378 - 384 2013年06月

ISSN  0006-291X

　概要を見る

<p>Th17 cells, which have been implicated in autoimmune diseases, require IL-6 and TGF-β for early differentiation. Several Smad-independent pathways including the JNK and the RhoA-ROCK pathways have been implicated in the induction of RORγt, the master regulator of Th17, however, molecular mechanisms underlying Smad-independent pathway remain largely unknown. To identify novel pathways involved in Th17 differentiation, we screened 285 chemical inhibitors for known signaling pathways. Among them, we found that Kenpaullone, a GSK3-β and CDK inhibitor, efficiently suppressed TGF-β-mediated RORγt induction and enhanced Foxp3 induction in primary T cells. Another CDK inhibitor, Roscovitine, but not other GSK3-β inhibitors, suppressed Th17 differentiation and enhanced iTreg development. Kenpaullone and Roscovitine suppressed experimental autoimmune encephalomyelitis (EAE), a typical Th17-mediated autoimmune disease model. These two compounds enhanced STAT5 phosphorylation and restored IL-2 production in the presence of TGF-β. These data suggest that CDK inhibitors modulate TGF-β-signaling pathways, which restore TGF-β-mediated suppression of IL-2 production, thereby modifying the Th17/iTreg balance. © 2013 Elsevier Inc.</p>

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CDK inhibitors suppress Th17 and promote iTreg differentiation, and ameliorate experimental autoimmune encephalomyelitis in mice

Yoshida Hideyuki, Kotani Hitoshi, Kondo Taisuke, Tani Ito, Wei Xuetao, Tsuruta Sanae, Kimura Akihiro, Asakawa Mayako, Ito Minako, Nagai Shigenori, Yoshimura Akihiko

Biochemical and Biophysical Research Communications 435 （ 3 ） 378 - 384 2013年06月

ISSN  0006-291X

　概要を見る

<p>Th17 cells, which have been implicated in autoimmune diseases, require IL-6 and TGF-β for early differentiation. Several Smad-independent pathways including the JNK and the RhoA-ROCK pathways have been implicated in the induction of RORγt, the master regulator of Th17, however, molecular mechanisms underlying Smad-independent pathway remain largely unknown. To identify novel pathways involved in Th17 differentiation, we screened 285 chemical inhibitors for known signaling pathways. Among them, we found that Kenpaullone, a GSK3-β and CDK inhibitor, efficiently suppressed TGF-β-mediated RORγt induction and enhanced Foxp3 induction in primary T cells. Another CDK inhibitor, Roscovitine, but not other GSK3-β inhibitors, suppressed Th17 differentiation and enhanced iTreg development. Kenpaullone and Roscovitine suppressed experimental autoimmune encephalomyelitis (EAE), a typical Th17-mediated autoimmune disease model. These two compounds enhanced STAT5 phosphorylation and restored IL-2 production in the presence of TGF-β. These data suggest that CDK inhibitors modulate TGF-β-signaling pathways, which restore TGF-β-mediated suppression of IL-2 production, thereby modifying the Th17/iTreg balance. © 2013 Elsevier Inc.</p>

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CLP1 links tRNA metabolism to progressive motor-neuron loss

Hanada Toshikatsu, Weitzer Stefan, Mair Barbara, Bernreuther Christian, Wainger Brian J., Ichida Justin, Hanada Reiko, Orthofer Michael, Cronin Shane J., Komnenovic Vukoslav, Minis Adi, Sato Fuminori, Mimata Hiromitsu, Yoshimura Akihiko, Tamir Ido, Rainer Johannes, Kofler Reinhard, Yaron Avraham, Eggan Kevin C., Woolf Clifford J., Glatzel Markus, Herbst Ruth, Martinez Javier, Penninger Josef M.

Nature 495 （ 7442 ） 474 - 480 2013年03月

ISSN  0028-0836

　概要を見る

<p>CLP1 was the first mammalian RNA kinase to be identified. However, determining its in vivo function has been elusive. Here we generated kinase-dead Clp1 (Clp1^K/K) mice that show a progressive loss of spinal motor neurons associated with axonal degeneration in the peripheral nerves and denervation of neuromuscular junctions, resulting in impaired motor function, muscle weakness, paralysis and fatal respiratory failure. Transgenic rescue experiments show that CLP1 functions in motor neurons. Mechanistically, loss of CLP1 activity results in accumulation of a novel set of small RNA fragments, derived from aberrant processing of tyrosine pre-transfer RNA. These tRNA fragments sensitize cells to oxidative-stress-induced p53 (also known as TRP53) activation and p53-dependent cell death. Genetic inactivation of p53 rescues Clp1^K/K mice from the motor neuron loss, muscle denervation and respiratory failure. Our experiments uncover a mechanistic link between tRNA processing, formation of a new RNA species and progressive loss of lower motor neurons regulated by p53. © 2013 Macmillan Publishers Limited. All rights reserved.</p>

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CLP1 links tRNA metabolism to progressive motor-neuron loss

Hanada Toshikatsu, Weitzer Stefan, Mair Barbara, Bernreuther Christian, Wainger Brian J., Ichida Justin, Hanada Reiko, Orthofer Michael, Cronin Shane J., Komnenovic Vukoslav, Minis Adi, Sato Fuminori, Mimata Hiromitsu, Yoshimura Akihiko, Tamir Ido, Rainer Johannes, Kofler Reinhard, Yaron Avraham, Eggan Kevin C., Woolf Clifford J., Glatzel Markus, Herbst Ruth, Martinez Javier, Penninger Josef M.

Nature 495 （ 7442 ） 474 - 480 2013年03月

ISSN  0028-0836

　概要を見る

<p>CLP1 was the first mammalian RNA kinase to be identified. However, determining its in vivo function has been elusive. Here we generated kinase-dead Clp1 (Clp1^K/K) mice that show a progressive loss of spinal motor neurons associated with axonal degeneration in the peripheral nerves and denervation of neuromuscular junctions, resulting in impaired motor function, muscle weakness, paralysis and fatal respiratory failure. Transgenic rescue experiments show that CLP1 functions in motor neurons. Mechanistically, loss of CLP1 activity results in accumulation of a novel set of small RNA fragments, derived from aberrant processing of tyrosine pre-transfer RNA. These tRNA fragments sensitize cells to oxidative-stress-induced p53 (also known as TRP53) activation and p53-dependent cell death. Genetic inactivation of p53 rescues Clp1^K/K mice from the motor neuron loss, muscle denervation and respiratory failure. Our experiments uncover a mechanistic link between tRNA processing, formation of a new RNA species and progressive loss of lower motor neurons regulated by p53. © 2013 Macmillan Publishers Limited. All rights reserved.</p>

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IL-6 trans-signaling promotes pancreatitis-associated lung injury and lethality

Zhang Hong, Neuhöfer Patrick, Song Liang, Rabe Björn, Lesina Marina, Kurkowski Magdalena U., Treiber Matthias, Wartmann Thomas, Regnér Sara, Thorlacius Henrik, Saur Dieter, Weirich Gregor, Yoshimura Akihiko, Halangk Walter, Mizgerd Joseph P., Schmid Roland M., Rose-John Stefan, Algül Hana

Journal of Clinical Investigation 123 （ 3 ） 1019 - 1031 2013年03月

ISSN  0021-9738

　概要を見る

<p>Acute lung injury (ALI) is an inflammatory disease with a high mortality rate. Although typically seen in individuals with sepsis, ALI is also a major complication in severe acute pancreatitis (SAP). The pathophysiology of SAP-associated ALI is poorly understood, but elevated serum levels of IL-6 is a reliable marker for disease severity. Here, we used a mouse model of acute pancreatitis-associated (AP-associated) ALI to determine the role of IL-6 in ALI lethality. Il6-deficient mice had a lower death rate compared with wild-type mice with AP, while mice injected with IL-6 were more likely to develop lethal ALI. We found that inflammation-associated NF-κB induced myeloid cell secretion of IL-6, and the effects of secreted IL-6 were mediated by complexation with soluble IL-6 receptor, a process known as trans-signaling. IL-6 trans-signaling stimulated phosphorylation of STAT3 and production of the neutrophil attractant CXCL1 in pancreatic acinar cells. Examination of human samples revealed expression of IL-6 in combination with soluble IL-6 receptor was a reliable predictor of ALI in SAP. These results demonstrate that IL-6 trans-signaling is an essential mediator of ALI in SAP across species and suggest that therapeutic inhibition of IL-6 may prevent SAP-associated ALI.</p>

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IL-6 trans-signaling promotes pancreatitis-associated lung injury and lethality

Zhang Hong, Neuhöfer Patrick, Song Liang, Rabe Björn, Lesina Marina, Kurkowski Magdalena U., Treiber Matthias, Wartmann Thomas, Regnér Sara, Thorlacius Henrik, Saur Dieter, Weirich Gregor, Yoshimura Akihiko, Halangk Walter, Mizgerd Joseph P., Schmid Roland M., Rose-John Stefan, Algül Hana

Journal of Clinical Investigation 123 （ 3 ） 1019 - 1031 2013年03月

ISSN  0021-9738

　概要を見る

<p>Acute lung injury (ALI) is an inflammatory disease with a high mortality rate. Although typically seen in individuals with sepsis, ALI is also a major complication in severe acute pancreatitis (SAP). The pathophysiology of SAP-associated ALI is poorly understood, but elevated serum levels of IL-6 is a reliable marker for disease severity. Here, we used a mouse model of acute pancreatitis-associated (AP-associated) ALI to determine the role of IL-6 in ALI lethality. Il6-deficient mice had a lower death rate compared with wild-type mice with AP, while mice injected with IL-6 were more likely to develop lethal ALI. We found that inflammation-associated NF-κB induced myeloid cell secretion of IL-6, and the effects of secreted IL-6 were mediated by complexation with soluble IL-6 receptor, a process known as trans-signaling. IL-6 trans-signaling stimulated phosphorylation of STAT3 and production of the neutrophil attractant CXCL1 in pancreatic acinar cells. Examination of human samples revealed expression of IL-6 in combination with soluble IL-6 receptor was a reliable predictor of ALI in SAP. These results demonstrate that IL-6 trans-signaling is an essential mediator of ALI in SAP across species and suggest that therapeutic inhibition of IL-6 may prevent SAP-associated ALI.</p>

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Overexpression of SOCS3 in T lymphocytes leads to impaired interleukin-17 production and severe aortic aneurysm formation in mice-brief report

Romain Mélissa, Taleb Soraya, Dalloz Marion, Ponnuswamy Padmapriya, Esposito Bruno, Pérez Nicolas, Wang Yu, Yoshimura Akihiko, Tedgui Alain, Mallat Ziad

Arteriosclerosis, Thrombosis, and Vascular Biology 33 （ 3 ） 581 - 584 2013年03月

ISSN  1079-5642

　概要を見る

<p>Objective-Mutations of signal transducer and activator of transcription 3 (STAT3) are responsible for autosomal dominant hyperimmunoglobulin E syndrome. Recently, we reported frequent vascular abnormalities, including aneurysms in these patients, and demonstrated that STAT3 inhibition promoted aneurysm in mice. The purpose of this study was to investigate the role of cell-specific STAT3 signaling in the susceptibility to aneurysm. Methods and Results-C57BL/6 wild-type mice were irradiated and repopulated with bone marrow cells isolated from either wild-type mice or from mice with defective STAT3 signaling as a result of overexpression of suppressor of cytokine signaling 3 (SOCS3-Tg mice). Mice were then subjected to a validated model of abdominal aortic aneurysm induced by angiotensin II infusion for 28 days, along with repetitive injections of a neutralizing antitransforming growth factor-β antibody. We found that overexpression of SOCS3 in bone marrow-derived cells significantly increased aneurysm severity (P=0.04). In contrast, overexpression of SOCS3 in the vessel wall had no effect on the disease process. Surprisingly, deletion of STAT3 signaling in macrophages did not affect aneurysm development. Interestingly, however, defective STAT3 signaling in SOCS3-Tg T cells markedly increased aneurysm severity (P=0.01) and mortality from aneurysm rupture (P=0.008). Overexpression of SOCS3 in T cells significantly decreased interleukin-17 production (P&lt;0.0001) and was associated with a reduction of its plasma levels (P=0.02). Conclusion-These findings clearly identify a central role for T cell-specific STAT3 signaling in the promotion of vascular aneurysm and support previous work on interleukin-17 protective role in this process. © 2013 American Heart Association, Inc.</p>

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[Peroxiredoxin triggers post-ischemic inflammation].

Yoshimura Akihiko, Ito Minako, Kondo Taisuke, Shichita Takashi

Seikagaku. The Journal of Japanese Biochemical Society 85 （ 3 ） 179 - 186 2013年03月

ISSN  0037-1017

Nr4a receptors are essential for thymic regulatory T cell development and immune homeostasis

Sekiya Takashi, Kashiwagi Ikkou, Yoshida Rei, Fukaya Tomohiro, Morita Rimpei, Kimura Akihiro, Ichinose Hiroshi, Metzger Daniel, Chambon Pierre, Yoshimura Akihiko

Nature Immunology 14 （ 3 ） 230 - 237 2013年03月

ISSN  1529-2908

　概要を見る

<p>Regulatory T cells (T reg cells) develop from progenitor thymocytes after the engagement of T cell antigen receptors (TCRs) with high-affinity ligands, but the underlying molecular mechanisms are still unclear. Here we show that the Nr4a nuclear receptors, which are encoded by immediate-early genes upregulated by TCR stimulation in thymocytes, have essential roles in T reg cell development. Mice that lacked all Nr4a factors could not produce T reg cells and died early owing to systemic autoimmunity. Nr4a receptors directly activated the promoter of the gene encoding the transcription factor Foxp3, and forced activation of Nr4a receptors bypassed low-strength TCR signaling to drive the T reg cell developmental program. Our results suggest that Nr4a receptors have key roles in determining CD4 + T cell fates in the thymus and thus contribute to immune homeostasis. © 2013 Nature America, Inc. All rights reserved.</p>

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Overexpression of SOCS3 in T lymphocytes leads to impaired interleukin-17 production and severe aortic aneurysm formation in mice-brief report

Romain Mélissa, Taleb Soraya, Dalloz Marion, Ponnuswamy Padmapriya, Esposito Bruno, Pérez Nicolas, Wang Yu, Yoshimura Akihiko, Tedgui Alain, Mallat Ziad

Arteriosclerosis, Thrombosis, and Vascular Biology 33 （ 3 ） 581 - 584 2013年03月

ISSN  1079-5642

　概要を見る

<p>Objective-Mutations of signal transducer and activator of transcription 3 (STAT3) are responsible for autosomal dominant hyperimmunoglobulin E syndrome. Recently, we reported frequent vascular abnormalities, including aneurysms in these patients, and demonstrated that STAT3 inhibition promoted aneurysm in mice. The purpose of this study was to investigate the role of cell-specific STAT3 signaling in the susceptibility to aneurysm. Methods and Results-C57BL/6 wild-type mice were irradiated and repopulated with bone marrow cells isolated from either wild-type mice or from mice with defective STAT3 signaling as a result of overexpression of suppressor of cytokine signaling 3 (SOCS3-Tg mice). Mice were then subjected to a validated model of abdominal aortic aneurysm induced by angiotensin II infusion for 28 days, along with repetitive injections of a neutralizing antitransforming growth factor-β antibody. We found that overexpression of SOCS3 in bone marrow-derived cells significantly increased aneurysm severity (P=0.04). In contrast, overexpression of SOCS3 in the vessel wall had no effect on the disease process. Surprisingly, deletion of STAT3 signaling in macrophages did not affect aneurysm development. Interestingly, however, defective STAT3 signaling in SOCS3-Tg T cells markedly increased aneurysm severity (P=0.01) and mortality from aneurysm rupture (P=0.008). Overexpression of SOCS3 in T cells significantly decreased interleukin-17 production (P&lt;0.0001) and was associated with a reduction of its plasma levels (P=0.02). Conclusion-These findings clearly identify a central role for T cell-specific STAT3 signaling in the promotion of vascular aneurysm and support previous work on interleukin-17 protective role in this process. © 2013 American Heart Association, Inc.</p>

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[Peroxiredoxin triggers post-ischemic inflammation].

Yoshimura Akihiko, Ito Minako, Kondo Taisuke, Shichita Takashi

Seikagaku. The Journal of Japanese Biochemical Society 85 （ 3 ） 179 - 186 2013年03月

ISSN  0037-1017

Nr4a receptors are essential for thymic regulatory T cell development and immune homeostasis

Sekiya Takashi, Kashiwagi Ikkou, Yoshida Rei, Fukaya Tomohiro, Morita Rimpei, Kimura Akihiro, Ichinose Hiroshi, Metzger Daniel, Chambon Pierre, Yoshimura Akihiko

Nature Immunology 14 （ 3 ） 230 - 237 2013年03月

ISSN  1529-2908

　概要を見る

<p>Regulatory T cells (T reg cells) develop from progenitor thymocytes after the engagement of T cell antigen receptors (TCRs) with high-affinity ligands, but the underlying molecular mechanisms are still unclear. Here we show that the Nr4a nuclear receptors, which are encoded by immediate-early genes upregulated by TCR stimulation in thymocytes, have essential roles in T reg cell development. Mice that lacked all Nr4a factors could not produce T reg cells and died early owing to systemic autoimmunity. Nr4a receptors directly activated the promoter of the gene encoding the transcription factor Foxp3, and forced activation of Nr4a receptors bypassed low-strength TCR signaling to drive the T reg cell developmental program. Our results suggest that Nr4a receptors have key roles in determining CD4 + T cell fates in the thymus and thus contribute to immune homeostasis. © 2013 Nature America, Inc. All rights reserved.</p>

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IL-23-independent induction of IL-17 from γδT cells and innate lymphoid cells promotes experimental intraocular neovascularization

Hasegawa Eiichi, Sonoda Koh Hei, Shichita Takashi, Morita Rimpei, Sekiya Takashi, Kimura Akihiro, Oshima Yuji, Takeda Atsunobu, Yoshimura Takeru, Yoshida Shigeo, Ishibashi Tatsuro, Yoshimura Akihiko

Journal of Immunology 190 （ 4 ） 1778 - 1787 2013年02月

ISSN  0022-1767

　概要を見る

<p>Choroidal neovascularization (CNV) is a characteristic of age-related macular degeneration. Genome-wide association studies have provided evidence that the immune system is involved in the pathogenesis of age-related macular degeneration; however, the role of inflammatory cytokines in CNV has not been established. In this study, we demonstrated that IL-17 had a strong potential for promoting neovascularization in a vascular endothelial growth factor-independent manner in laser-induced experimental CNV in mice. Infiltrated γδT cells and Thy-1⁺ innate lymphoid cells, but not Th17 cells, were the main sources of IL-17 in injured eyes. IL-23 was dispensable for IL-17 induction in the eye. Instead, we found that IL-1β and high-mobility group box 1 strongly promoted IL-17 expression by γδT cells. Suppression of IL-1β and high-mobility group box 1, as well as depletion of γδT cells, reduced IL-17 levels and ameliorated experimental CNV. Our findings suggest the existence of a novel inflammatory cytokine network that promotes neovascularization in the eye. Copyright © 2013 by The American Association of Immunologists, Inc.</p>

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IL-23-independent induction of IL-17 from γδT cells and innate lymphoid cells promotes experimental intraocular neovascularization

Hasegawa Eiichi, Sonoda Koh Hei, Shichita Takashi, Morita Rimpei, Sekiya Takashi, Kimura Akihiro, Oshima Yuji, Takeda Atsunobu, Yoshimura Takeru, Yoshida Shigeo, Ishibashi Tatsuro, Yoshimura Akihiko

Journal of Immunology 190 （ 4 ） 1778 - 1787 2013年02月

ISSN  0022-1767

　概要を見る

<p>Choroidal neovascularization (CNV) is a characteristic of age-related macular degeneration. Genome-wide association studies have provided evidence that the immune system is involved in the pathogenesis of age-related macular degeneration; however, the role of inflammatory cytokines in CNV has not been established. In this study, we demonstrated that IL-17 had a strong potential for promoting neovascularization in a vascular endothelial growth factor-independent manner in laser-induced experimental CNV in mice. Infiltrated γδT cells and Thy-1⁺ innate lymphoid cells, but not Th17 cells, were the main sources of IL-17 in injured eyes. IL-23 was dispensable for IL-17 induction in the eye. Instead, we found that IL-1β and high-mobility group box 1 strongly promoted IL-17 expression by γδT cells. Suppression of IL-1β and high-mobility group box 1, as well as depletion of γδT cells, reduced IL-17 levels and ameliorated experimental CNV. Our findings suggest the existence of a novel inflammatory cytokine network that promotes neovascularization in the eye. Copyright © 2013 by The American Association of Immunologists, Inc.</p>

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Nr4a receptors are essential for thymic regulatory T cell development and immune homeostasis

Sekiya Takashi, Kashiwagi Ikkou, Yoshida Rei, Fukaya Tomohiro, Morita Rimpei, Kimura Akihiro, Ichinose Hiroshi, Metzger Daniel, Chambon Pierre, Yoshimura Akihiko

Nature Immunology 2013年01月

ISSN  1529-2908

　概要を見る

<p>Regulatory T cells (T_reg cells) develop from progenitor thymocytes after the engagement of T cell antigen receptors (TCRs) with high-affinity ligands, but the underlying molecular mechanisms are still unclear. Here we show that the Nr4a nuclear receptors, which are encoded by immediate-early genes upregulated by TCR stimulation in thymocytes, have essential roles in T_reg cell development. Mice that lacked all Nr4a factors could not produce T_reg cells and died early owing to systemic autoimmunity. Nr4a receptors directly activated the promoter of the gene encoding the transcription factor Foxp3, and forced activation of Nr4a receptors bypassed low-strength TCR signaling to drive the T_reg cell developmental program. Our results suggest that Nr4a receptors have key roles in determining CD4⁺ T cell fates in the thymus and thus contribute to immune homeostasis.</p>

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Nr4a receptors are essential for thymic regulatory T cell development and immune homeostasis

Sekiya Takashi, Kashiwagi Ikkou, Yoshida Rei, Fukaya Tomohiro, Morita Rimpei, Kimura Akihiro, Ichinose Hiroshi, Metzger Daniel, Chambon Pierre, Yoshimura Akihiko

Nature Immunology 2013年01月

ISSN  1529-2908

　概要を見る

<p>Regulatory T cells (T_reg cells) develop from progenitor thymocytes after the engagement of T cell antigen receptors (TCRs) with high-affinity ligands, but the underlying molecular mechanisms are still unclear. Here we show that the Nr4a nuclear receptors, which are encoded by immediate-early genes upregulated by TCR stimulation in thymocytes, have essential roles in T_reg cell development. Mice that lacked all Nr4a factors could not produce T_reg cells and died early owing to systemic autoimmunity. Nr4a receptors directly activated the promoter of the gene encoding the transcription factor Foxp3, and forced activation of Nr4a receptors bypassed low-strength TCR signaling to drive the T_reg cell developmental program. Our results suggest that Nr4a receptors have key roles in determining CD4⁺ T cell fates in the thymus and thus contribute to immune homeostasis.</p>

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Biocompatible fluorescent silicon nanocrystals for single-molecule tracking and fluorescence imaging

Nishimura Hirohito, Ritchie Ken, Kasai Rinshi S., Goto Miki, Morone Nobuhiro, Sugimura Hiroyuki, Tanaka Koichiro, Sase Ichiro, Yoshimura Akihiko, Nakano Yoshitaro, Fujiwara Takahiro K., Kusumi Akihiro

Journal of Cell Biology 202 （ 6 ） 967 - 983 2013年

ISSN  0021-9525

　概要を見る

<p>Fluorescence microscopy is used extensively in cellbiological and biomedical research, but it is often plagued by three major problems with the presently available fluorescent probes: photobleaching, blinking, and large size. We have addressed these problems, with special attention to single-molecule imaging, by developing biocompatible, red-emitting silicon nanocrystals (SiNCs) with a 4.1-nm hydrodynamic diameter. Methods for producing SiNCs by simple chemical etching, for hydrophilically coating them, and for conjugating them to biomolecules precisely at a 1:1 ratio have been developed. Single SiNCs neither blinked nor photobleached during a 300-min overall period observed at video rate. Single receptor molecules in the plasma membrane of living cells (using transferrin receptor) were imaged for =10 times longer than with other probes, making it possible for the first time to observe the internalization process of receptor molecules at the single-molecule level. Spatial variations of molecular diffusivity in the scale of 1-2 μm, i.e., a higher level of domain mosaicism in the plasma membrane, were revealed. ©2013 Nishimura et al.</p>

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Biocompatible fluorescent silicon nanocrystals for single-molecule tracking and fluorescence imaging

Nishimura Hirohito, Ritchie Ken, Kasai Rinshi S., Goto Miki, Morone Nobuhiro, Sugimura Hiroyuki, Tanaka Koichiro, Sase Ichiro, Yoshimura Akihiko, Nakano Yoshitaro, Fujiwara Takahiro K., Kusumi Akihiro

Journal of Cell Biology 202 （ 6 ） 967 - 983 2013年

ISSN  0021-9525

　概要を見る

<p>Fluorescence microscopy is used extensively in cellbiological and biomedical research, but it is often plagued by three major problems with the presently available fluorescent probes: photobleaching, blinking, and large size. We have addressed these problems, with special attention to single-molecule imaging, by developing biocompatible, red-emitting silicon nanocrystals (SiNCs) with a 4.1-nm hydrodynamic diameter. Methods for producing SiNCs by simple chemical etching, for hydrophilically coating them, and for conjugating them to biomolecules precisely at a 1:1 ratio have been developed. Single SiNCs neither blinked nor photobleached during a 300-min overall period observed at video rate. Single receptor molecules in the plasma membrane of living cells (using transferrin receptor) were imaged for =10 times longer than with other probes, making it possible for the first time to observe the internalization process of receptor molecules at the single-molecule level. Spatial variations of molecular diffusivity in the scale of 1-2 μm, i.e., a higher level of domain mosaicism in the plasma membrane, were revealed. ©2013 Nishimura et al.</p>

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TAK1 (MAP3K7) Signaling Regulates Hematopoietic Stem Cells through TNF-Dependent and -Independent Mechanisms

Takaesu Giichi, Inagaki Maiko, Takubo Keiyo, Mishina Yuji, Hess Paul R., Dean Gregg A., Yoshimura Akihiko, Matsumoto Kunihiro, Suda Toshio, Ninomiya-Tsuji Jun

PLoS ONE 7 （ 11 ）  2012年11月

　概要を見る

<p>A cytokine/stress signaling kinase Tak1 (Map3k7) deficiency is known to impair hematopoietic progenitor cells. However, the role of TAK1 signaling in the stem cell function of the hematopoietic system is not yet well defined. Here we characterized hematopoietic stem cells (HSCs) harboring deletion of Tak1 and its activators, Tak1 binding proteins 1 and 2 (Tab1 and Tab2) using a competitive transplantation assay in a mouse model. Tak1 single or Tab1/Tab2 double deletions completely eliminated the reconstitution activity of HSCs, whereas Tab1 or Tab2 single deletion did not cause any abnormality. Tak1 single or Tab1/Tab2 double deficient lineage-negative, Sca-1⁺, c-Kit⁺ (LSK) cells did not proliferate and underwent cell death. We found that Tnfr1 deficiency restored the reconstitution activity of Tak1 deficient bone marrow cells for 6-18 weeks. However, the reconstitution activity of Tak1- and Tnfr1-double deficient bone marrow cells declined over the long term, and the number of phenotypically identified long-term hematopoietic stem cells were diminished. Our results indicate that TAB1- or TAB2-dependent activation of TAK1 is required for maintenance of the hematopoietic system through two mechanisms: one is prevention of TNF-dependent cell death and the other is TNF-independent maintenance of long-term HSC. © 2012 Takaesu et al.</p>

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TAK1 (MAP3K7) Signaling Regulates Hematopoietic Stem Cells through TNF-Dependent and -Independent Mechanisms

Takaesu Giichi, Inagaki Maiko, Takubo Keiyo, Mishina Yuji, Hess Paul R., Dean Gregg A., Yoshimura Akihiko, Matsumoto Kunihiro, Suda Toshio, Ninomiya-Tsuji Jun

PLoS ONE 7 （ 11 ）  2012年11月

　概要を見る

<p>A cytokine/stress signaling kinase Tak1 (Map3k7) deficiency is known to impair hematopoietic progenitor cells. However, the role of TAK1 signaling in the stem cell function of the hematopoietic system is not yet well defined. Here we characterized hematopoietic stem cells (HSCs) harboring deletion of Tak1 and its activators, Tak1 binding proteins 1 and 2 (Tab1 and Tab2) using a competitive transplantation assay in a mouse model. Tak1 single or Tab1/Tab2 double deletions completely eliminated the reconstitution activity of HSCs, whereas Tab1 or Tab2 single deletion did not cause any abnormality. Tak1 single or Tab1/Tab2 double deficient lineage-negative, Sca-1⁺, c-Kit⁺ (LSK) cells did not proliferate and underwent cell death. We found that Tnfr1 deficiency restored the reconstitution activity of Tak1 deficient bone marrow cells for 6-18 weeks. However, the reconstitution activity of Tak1- and Tnfr1-double deficient bone marrow cells declined over the long term, and the number of phenotypically identified long-term hematopoietic stem cells were diminished. Our results indicate that TAB1- or TAB2-dependent activation of TAK1 is required for maintenance of the hematopoietic system through two mechanisms: one is prevention of TNF-dependent cell death and the other is TNF-independent maintenance of long-term HSC. © 2012 Takaesu et al.</p>

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