粒線體在細胞能量產生和細胞內平衡的維持中扮演著關鍵的角色。這項研究探討了Dosmit（一種鐵硫蛋白質）和Hsp22對粒線體功能的影響，以及它們在細胞過程中的潛在參與。研究發現Dosmit的表達會降低Fe2+含量，表明可能會改變鐵代謝。此外，Dosmit的過度表達導致活性氧化物質（ROS）水平增加，顯示氧化反應加劇。研究還發現Dosmit的過度表達增強了熱休克蛋白22（Hsp22）進入粒線體的攝取，可能指出對粒線體的壓力有保護性反應。這些發現闡明Dosmit影響能量產生，並可能參與鐵調控和三羧酸循環（TCA cycle）活動。
Hsp22是一種受粒線體壓力誘導的粒線體伴護蛋白，在Dosmit過度表達時被觀察到進入粒線體。粒線體的蛋白質摺疊不正常反應（UPRmt）會在線粒體基質中出現未展開或錯誤摺疊的蛋白質時被啟動。此外，蛋白質降解的途徑，包括Lon蛋白酶、ATG8a和PINK1，在維持細胞內恆定和粒線體完整性方面有著關鍵作用。儘管這些實驗大多沒有顯著差異，但它們為我們提供了一些關於ATG8a和PINK1之間相關性的見解。因此需要進一步的研究全面闡明Dosmit和Hsp22在細胞功能中的精確機制和意義。

Mitochondria play a crucial role in cellular energy production and maintenance of cellular homeostasis. This study investigates the impact of Dosmit, an iron-sulfur protein, and Hsp22 on mitochondrial function and their potential involvement in cellular processes. The expression of Dosmit was found to decrease Fe2+ content, indicating a potential alteration in iron metabolism. Additionally, Dosmit overexpression resulted in increased levels of reactive oxygen species (ROS), indicating elevated oxidative stress. The study also revealed that Dosmit overexpression enhanced the uptake of heat shock protein 22 (Hsp22) into mitochondria, potentially indicating a protective response to mitochondrial stress. These findings demonstrate that Dosmit influences energy production and may be involved in iron regulation and the tricarboxylic acid (TCA) cycle activity.
Hsp22, a mitochondrial chaperone induced by mitochondrial stress, is observed to be transported into mitochondria upon Dosmit overexpression. The mitochondrial unfolded protein response (UPRmt) is activated in response to unfolded or misfolded proteins in the mitochondrial matrix. Otherwise, protein degradation pathways, including Lon protease, ATG8a, and PINK1, are crucial for maintaining cellular homeostasis and mitochondrial integrity. Although most of these experiments did not show significant differences, they provided us with some insights into the correlation with ATG8a and PINK1. Further research is needed to fully elucidate the precise mechanisms and implications of Dosmit and Hsp22 in cellular functions.

Abstract i
中文摘要 ii
Acknowledgement iii
Introduction 1
1.1 Overexpression of mitochondrial-associated protein Dosmit affects the mitochondrial morphology 1
1.2 Iron in mitochondrial physiology 1
1.3 The mechanism of mitochondrial unfolded protein response (UPRmt) 3
1.4 The function of Hsp22 3
1.5 Protein Degradation Pathway in cells 4
Material and Methods 6
2.1 Fly stocks 6
2.2 Immunofluorescent staining of Drosophila muscle 6
2.3 ATP Bioluminescence assay 6
2.4 Live image 7
2.5 Aconitase assay 7
2.6 Iron assay 8
2.7 Real-time PCR (qPCR) 8
2.8 Western blotting 9
2.9 Proteomic analysis 11
2.10 Lifespan assay 13
2.11 Mitochondrial isolation from Drosophila flight-muscle tissue 13
2.12 Statistics 13
Results 14
3.1 The exist of Dosmit does not affect the ATP production and membrane potential 14
3.2 Dosmit overexpression does not have an effect on Aconitase activity 15
3.3 Dosmit mutant increases Fe2+ in mitochondria of the muscle tissue 15
3.4 Dosmit overexpression increases the ROS levels 16
3.5 Dosmit overexpression significantly increases Hsp22 in mitochondria 17
3.6 Deficiency and overexpression of Hsp22 do not change mitochondrial morphology 18
3.7 Hsp22 does not have an effect on the RNA level of UPRmt-related targets 19
3.8 Hsp22 increases its protein level during aging but it does not affect lifespan 20
3.9 Knockout of Hsp22 does not affect lifespan and protein degradation 20
3.10 The exist of Hsp22 does not mainly affect ROS 21
3.11 Influence of Hsp22 on protein levels of LONP1 and ATG8a 22
3.12 Elevated Hsp22 expression induced by mutation of PINK1 22
Discussion 24
Figures 26
Tables 51
Table 1. List of fly stocks 51
Table 2. List of antibodies 52
Table 3. List of dyes 53
Table 4. List of primers 53
Reference 54

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