トクシマ ダイガク エイヨウ ガッカ ハツ ウチュウ ジッケン ノ アユミ ト コレカラ

Yuri Gagarin said,“The Earth is blue”, in the first manned spacecraft Vostok 1 in April 1961 when he glimpsed the planet from the space. Since then, human beings have been evolving technology of rocket, so that they can stay in space for several months and years. In Japan, JAXA has almost finished constructing“Kibo”, a space experimental module in the International Space Station（ISS）, in August, 2008. The first space research of Japan will be carried out at“Kibo”soon.We are also planning to perform a space experiment in“Kibo”to clarify the molecular mechanism of muscle atrophy caused by micro gravity. In this paper, we report our history and future plan to develop space research

自発的高運動ラットの安静時遺伝子発現パターンと野生型ラット運動時遺伝子発現パターンの違い

The Spontaneously-Running Tokushima Shikoku (SPORTS) strain is an original line derived from Wistar rats, which spontaneously runs >6 km/day on wheels, and has better glucose tolerance and less fat than Wistar rats. However, the molecular mechanism that contributes to the increased metabolic activity in SPORTS rats is unknown. The present study aimed to characterize the gene expression profiles of skeletal muscles in SPORTS rats housed under sedentary (SED) conditions. We found that the expression levels of genes encoding mitochondrial respiratory chain enzymes such as ATP synthase 6 (mt-Atp6) and cytochrome c oxidase subunit 6c (Cox 6c), were higher in the soleus (SOL) muscles of SED SPORTS than in SED Wistar rats. The ratio of type IIa myofibers was higher and glucose tolerance was better in SED SPORTS than in Wistar rats that were sedentary and trained daily on treadmills, respectively. We then investigated candidate genes that might contribute to the better glucose tolerance of SED SPORTS rats using DNA microarray analysis. Among 116 upregulated genes in the SOL muscles of SED SPORTS rats, only 19 were also increased in trained Wistar rats. We focused on v-erb-b2 erythroblastic leukemia viral oncogene homolog 3 (Erbb3), which was associated with glucose transport in myocytes, and found higher expression levels in the SOL muscles of SED SPORTS than in SED Wistar rats. The SOL muscles of SED SPORTS rats also contained more activity of β-hydroxy-acylCoA dehydrogenase, a key enzyme of β-oxidation, indicating enhanced lipid oxidation. These findings suggest that increased metabolic activity in skeletal muscle (especially the SOL muscle) of SPORTS rats is congenital and that gene expression profiles of SPORTS rats and Trained Wistar rats are different

Polyphenols prevent clinorotation-induced expression of atrogenes in mouse C2C12 skeletal myotubes

Oxidative stress is a key factor in stimulating the expression of atrogenes, which are muscle atrophy-related ubiquitin ligases, in skeletal muscle, and it induces muscle atrophy during unloading. However, the effects of antioxidative nutrients on atrogene expression have not been demonstrated. We report on the inhibitory effects of polyphenols, such as epicatechin (EC), epicatechin gallate (ECg) and epigallocatechin gallate (EGCg) and quercetin, on atrogene expression up-regulated by three dimensional (3D)-clinorotation or glucocorticoid. These treatments markedly elevated the expression of atrogenes, including atrogin-1 and MuRF-1, in mouse C2C12 myoblasts and myotubes. Interestingly, EC, ECg, EGCg and quercetin significantly decreased the expression of atrogin-1 and MuRF-1 up-regulated by 3D-clinorotation, whereas they hardly affected atrogene expression induced by dexamethasone. ERK signaling is a well known MAPK pathway to mediate oxidative stress. Therefore, we also investigated the effect of these polyphenols on phosphorylation of ERK in C2C12 myotubes. As expected, EC, ECg, EGCg, and quercetin significantly suppressed phosphorylation of ERK, corresponding to the up-regulation of atrogenes induced by 3D-clinorotation. These results suggest that antioxidative nutrients, such as catechins and quercetin, suppress atrogene expression in skeletal muscle cells, possibly through the inhibition of ERK signaling. Thus, catechins and quercetin may prevent unloading-mediated muscle atrophy