PPAR-γ coactivator-1 (PGC-1α) 是DNA轉錄因子的共同調控因子，參與在能量代謝的調控機制中，並且與肌肉纖維型態轉換有關。 當細胞受到外在環境的刺激，例如:冷，PGC-1α會被大量誘導表現。在之前已被證實PGC-1α可以和PPARγ及Mef2c共同調控其下游及自身基因的活化。 Stra13在轉錄層次上大部分扮演抑制者的功能，它是一個basic helix loop helix (bHLH)的轉錄因子。這一類的轉錄因子利用鹼性的區段與DNA的固有序列結合，Stra13屬於bHLH轉錄因子的E group，但是結合的DNA固有序列卻是B group 結合的位置。 在本實驗室的研究中發現，Stra13可以抑制MyoD對於PGC-1α的transactivation的能力。在我們的研究當中，想要去了解PGC-1α和Stra13兩個蛋白質之間的交互作用，以及兩者交互作用對於PGC-1α和Stra13下游調控的基因的影響。在cell free的實驗方面，已知道PGC-1α和Stra13會有很強的結合能力，我們利用GST pull down assay的方式去觀察到PGC-1α主要利用1-128 a.a.的位置和Stra13交互作用，而Stra13則是利用1-135 a.a.的位置與PGC-1α交互作用。 接著在in cell的實驗方面，將針對PGC-1α下游的調控基因，藉由nuclear respiratory factor和nuclear recptor活化後，觀察PGC-1α和Stra13交互作用的影響。利用同樣的方式觀察Stra13下游基因會不會受到影響。在未來希望能建立PGC-1α-flag穩定表現之細胞株，然後以co-immunoprecipitation的方式，觀察PGC-1α與Stra13在in cell的交互作用情形。

PPAR-γ coactivator-1 (PGC-1α) serve as a coregulators of DNA-binding transcription factors controlling energy metabolism. It is implicated in the muscle fiber type- switching, response to cold exposure and other cellular energy metabolisms. Interestingly, it has also been shown that PGC-1α can coactivate PPARγ- and Mef2c-dependent activation of its own gene. Stra13 is a basic helix-loop-helix (bHLH) containing transcriptional repressor of the E group but binds to the consensus motif as B group factors. In our recent study, we found that Stra13 can repress MyoD transactivation of PGC-1α promoter activity. In this study, we are interested in the interaction between PGC-1α and Stra13 on PGC-1α- and Stra13-dependent genes. In cell-free system, pull down assay indicated that PGC-1α binds to Stra13 strongly. We also defined the regions of PGC-1α (1-128) amino acid play an important role in the interaction with Stra13. And Stra13 (1-135) amino acid is the major region which interacts with PGC-1α. To go a step further, our study is to find out whether the interaction between PGC-1α and Stra13 affects the activation of PGC-1α-dependent genes by nuclear respiratory factor and nuclear receptors. Similarly, it is also of interest to know the response of Stra13 target genes to the presence of PGC-1α. In the future, we will use co-immunoprecipitation assay as an in-cell system to reveal that their interaction.

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