Forkhead box O (FoxO)轉錄因子成員包含FoxO1、FoxO3、FoxO4、FoxO6。已知其在細胞中調控著各種生理功能，如:細胞週期、葡萄糖代謝、DNA的修復、細胞的分化及凋亡等。FoxO家族中的FoxO6是近期才被發現，它不同於家族其他成員缺少了C端保守的PKB磷酸位，這使得他的進出細胞核的能力受到影響，因此相較其它成員它偏好留在細胞核內。目前已知FoxO6主要表現在大腦組織，但在肌肉組織中也發現到FoxO6的表現，過去文獻報導指出FoxO3會去活化Atrogen-1與MuRF1等ubiquitin ligase的表現，進而促使肌肉走向萎縮，由於目前對FoxO6在骨骼肌中所扮演的角色尚未釐清，因此我們想探討FoxO6對骨骼肌的影響，其中在小鼠後腿缺血的實驗中，我們觀察到FoxO6在缺血的狀態下蛋白質的表現量會上升。另外在C2C12肌纖維母細胞FoxO6 knock down細胞株中，發現到FoxO6遭受到抑制時Atrogen-1及MuRF1基因的表現量上升，這與FoxO家族其它成員似乎是相反的結果。另外我們想藉由Tet Off系統，探討當FoxO6被大量表達時對肌纖維母細胞的影響，所以我們目標建立一株可以藉由Tetracycline(Tet)調控FoxO6表達的細胞株。另一方面，由Schmidt團隊公布的FoxO6 CDS與IMAGE clone的CDS，其FoxO6蛋白質大小分別為559胺基酸及640胺基酸，但這與我們所觀察到的大小有所差異，所以我們合理的懷疑FoxO6在5'UTR，是否存在一段未曾被揭露的轉錄起始序列。我們從FoxO6 5'RACE的實驗中成功地找到FoxO6新的轉錄起始序列。未來我們希望能從肌纖維母細胞中，藉由大量表達FoxO6及抑制FoxO6的方式，分別探討對肌肉細胞代謝基因的影響及肌肉細胞分化情形。; Characterizing FoxO6 gene in mouse skeletal muscle
Forkhead box O (FoxO) transcription factor family that membrane, including FoxO1, FoxO3, FoxO4 and FoxO6 are they crucial for the regulation of metabolism, cell cycle, cell death, and cell survival. Among these FoxOs, the recently discovered FoxO6 is differs from other by lacking C-terminal PKB sites and which impairs its subcellular shuttling ability. FoxO6 is not only majorly expressed in the tissue of brain, but also expressed in the muscle. In the past, the reported that FoxO could activated Atrogen-1and MuRF1, which ubiquitin ligase expressed lead to muscle atrophy. However, the function of FoxO6 in skeletal muscle and the subcellular and fiber-type specific localization during myogenesis in vitro and in vivo are largely unknown. In addition, whether FoxO6 participates in muscle ischemia has not been reported before. We find out FoxO6 protein has higly expression in the muscle ischemia. In addition, we also discover both of the Atrogen-1 and MuRF1 are higly expression in the C2C12 FoxO6 knock down cell line. This result is obvisouly different to other FoxO members. On the other hand, we want to set up a Tet Off FoxO6 cell line system that could swithch gene on and off by tetracycline. In another aspect the size of FoxO6 is 559 and 640 amino acids that FoxO6 has reported by team of Schmidt and IMAGE clone. But the size of FoxO6 is different from them by our observating. So we guess the pass reported sequence that is not FoxO6 whole sequence. It may have another undiscover sequenc in FoxO6 5' UTR. We successful to discover a new FoxO6 sequence with transcription start site. In the future we hope to clarify the character of FoxO6 in the muscle cell by overexpression and knock its expression.
