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Aomori Shi, Japan

Hirosaki Gakuin University is a private university at Hirosaki, Aomori Prefecture, Japan. The predecessor of the school was founded in 1886, and it was chartered as a university in 1971. Wikipedia.


Kawano F.,Osaka University | Goto K.,Toyohashi Sozo University | Wang X.D.,Osaka University | Terada M.,Osaka University | And 4 more authors.
Journal of Applied Physiology | Year: 2010

Effects of gravitationalloading or unloading on the gain of the characteristics in soleus muscle fibers were studied in rats. The tail suspension was performed in newborn rats from postnatal day 4 to month 3, and the reloading was allowed for 3 mo in some rats. Single expression of type I myosin heavy chain (MHC) was observed in ∼82% of fibers in 3-mo-old controls, but the fibers expressing multiple MHC isoforms were noted in the unloaded rats. Although 97% of fibers in 3-mo-old controls had a single neuromuscular junction at the central region of fiber, fibers with multiple nerve endplates were seen in the unloaded group. Faster contraction speed and lower maximal tension development, even after normalization with fiber size, were observed in the unloaded pure type I MHC fibers. These parameters generally returned to the age-matched control levels after reloading. It was suggested that antigravity-related tonic activity plays an important role in the gain of single neural innervation and of slow contractile properties and phenotype in soleus muscle fibers. Copyright © 2010 the American Physiological Society.


Ohno Y.,Laboratory of Physiology | Ohno Y.,Nagoya University | Yamada S.,Nagoya University | Sugiura T.,Yamaguchi University | And 4 more authors.
Cells Tissues Organs | Year: 2011

Heat stress is one of the hypertrophic stimuli on mammalian skeletal muscle. Nuclear factor-κB (NF-κB) signaling plays an important role in the regulation of skeletal muscle mass. However, the effects of heat stress on NF-κB signaling in skeletal muscle cells remain unclear. Effects of heat stress and/or administration of BAY11-7082, an inhibitor of NF-κB, on NF-κB signals and protein content of skeletal muscle were studied by using cell culture system. Differentiated mouse myoblasts (C2C12) were subjected to either (1) control (cultured at 37°C without BAY11-7082), (2) heat stress at 41°C for 60 min, (3) BAY11-7082 administration (1.25 μM) or (4) heat stress combined with BAY11-7082 administration. Heat shock protein 72 (HSP72) was upregulated by heat stress with or without administration of BAY11-7082. The increase in inhibitor of κBα (IκBα), which regulates the phosphorylation of NF-κB, and the decrease in phosphorylated NF-κB were also induced by administration of BAY11-7082 and/or heat stress. Protein content in C2C12 cells was increased by the administration of BAY11-7082 with a semi-logarithm fashion. Significant increases in the protein content of C2C12 cells were observed 48 h following heating with or without administration of BAY11-7082. These observations suggest that heat stress might increase muscle protein through the downregulation of NF-κB signaling. Inhibition of NF-κB induced by application of heat stress might be one of the hypertrophic stimuli on skeletal muscle cells. Copyright © 2011 S. Karger AG, Basel.


Ohno Y.,Toyohashi Sozo University | Yamada S.,Nagoya University | Goto A.,Toyohashi Sozo University | Ikuta A.,Toyohashi Sozo University | And 4 more authors.
Molecular and Cellular Biochemistry | Year: 2012

Effects of heat stress on skeletal muscle mass in young and aged mice were investigated. Young (7-week) and aged (106-week) male C57BL/6J mice were randomly assigned to control and heat-stressed groups in each age. Mice in heat-stressed group were exposed to heat stress (41 °C for 60 min) in an incubator without anesthesia. Seven days after the exposure, soleus muscles were dissected from both hindlimbs. Protein content and the relative composition of Type II fibers in aged soleus were lower than those in young muscle. In aged soleus, higher baseline expression levels of HSP25, HSP72, and cathepsin L were observed compared with those in young muscle (p < 0.05). However, there were no significant differences in the expression levels of phosphorylated p70 S6 kinase (p-p70S6K), calpain 1, and calpain 2 of soleus between two age groups. A significant increase in muscle mass of both age groups was induced by heat stress (p < 0.05). Heat stress also upregulated the expressions of HSP25, HSP72, and p-p70S6K in both ages (p < 0.05). On the other hand, a significant decrease in cathepsin L expression by heating was observed in aged soleus, but not in young (p < 0.05). Both the percentage of Type I fibers and the expression of calpains in both age groups were unchanged following heat stress. Heat stress-associated downregulation of cathepsin L may be attributed to the upregulation of HSP72, which stabilizes lysosomal membranes (p < 0.05). Upregulations of HSP25, HSP72, and p-p70S6K and/or the downregulation of cathepsin L may play a role in heat stress-associated muscle hypertrophy in aged soleus muscle. © 2012 Springer Science+Business Media, LLC.


Ohno Y.,Toyohashi Sozo University | Ohno Y.,Nagoya University | Yamada S.,Nagoya University | Sugiura T.,Yamaguchi University | And 3 more authors.
General Physiology and Biophysics | Year: 2010

Effects of heat stress on phosphorylated nuclear factor-κ (phospho-NF-κ) and tumor necrosis factor α (TNFα) contents in skeletal muscles were studied. Male Wistar rats (7-week-old) were randomly assigned to control and heat-stressed groups. Rats in heat-stressed group were exposed to heat stress (42°C for 60 min) in an incubator without anesthesia. Soleus muscles were dissected and weighted 1, 3, and 7 days after the heat exposure. Significant increases in the wet weight and protein content of soleus were observed 7 days following the exposure (p < 0.05). Heat stress also induced the up-regulation of heat shock protein 72 (HSP72), IκBα (inhibitor of NF-κB) and the increase in the relative population of Pax7-positive satellite cells to total muscle nuclei before the increase in muscle mass. The content levels of phospho-NF-κB and TNFα were significantly decreased 1 and 3 days after heat stress, respectively (p < 0.05). A negative correlation between HSP72 and phospho-NF-κB contents was observed 1 day after the heat exposure. These observations suggest that the decrease in NF-κ signaling may play a part of a role in heat stress-associated muscle hypertrophy.


Egawa T.,Toyohashi Sozo University | Ohno Y.,Toyohashi Sozo University | Goto A.,Toyohashi Sozo University | Ikuta A.,Toyohashi Sozo University | And 7 more authors.
American Journal of Physiology - Endocrinology and Metabolism | Year: 2014

5'-AMP-activated protein kinase (AMPK) plays an important role as a negative regulator of skeletal muscle mass. However, the precise mechanism of AMPK-mediated regulation of muscle mass is not fully clarified. Heat shock proteins (HSPs), stress-induced molecular chaperones, are related with skeletal muscle adaptation, but the association between AMPK and HSPs in skeletal muscle hypertrophy is unknown. Thus, we investigated whether AMPK regulates hypertrophy by mediating HSPs in C2C12 cells. The treatment with AICAR, a potent stimulator of AMPK, decreased 72-kDa HSP (HSP72) expression, whereas there were no changes in the expressions of 25-kDa HSP, 70-kDa heat shock cognate, and heat shock transcription factor 1 in myotubes. Protein content and diameter were less in the AICAR-treated myotubes in those without treatment. AICAR-induced suppression of myotube hypertrophy and HSP72 expression was attenuated in the siRNA-mediated AMPKα knockdown myotubes. AICAR increased microRNA (miR)-1, a modulator of HSP72, and the increase of miR-1 was not induced in AMPKα knockdown condition. Furthermore, siRNA-mediated HSP72 knockdown blocked AICAR-induced inhibition of myotube hypertrophy. AICAR upregulated the gene expression of muscle Ring-finger 1, and this alteration was suppressed in either AMPKα or HSP72 knockdown myotubes. The phosphorylation of p70 S6 kinase Thr389 was downregulated by AICAR, whereas this was attenuated in AMPKα, but not in HSP72, knockdown myotubes. These results suggest that AMPK inhibits hypertrophy through, in part, an HSP72-associated mechanism via miR-1 and protein degradation pathways in skeletal muscle cells. © 2014 the American Physiological Society.

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