TIMM50, also called TIM50, is an essential component of the TIM23 complex in the mitochondrial inner membrane. It plays a crucial role in importing cytosolic proteins containing a mitochondrial targeting presequence into the mitochondrial inner compartment, thus facilitating the import of about 60% of the mitochondrial proteome [3,4,6,7]. This process is vital for maintaining proper mitochondrial function, which is involved in energy production, cell survival, and various biological processes [3,4].

In diseases, TIMM50 has been implicated in multiple conditions. In colorectal cancer, high TIMM50 expression is related to pathologic stage, N stage, and distant metastasis, and patients with high TIMM50 expression have a shorter overall survival, suggesting it could be a prognosis indicator [1]. In non-small cell lung cancer, TIMM50 promotes tumor proliferation and invasion through the ERK/P90RSK signaling pathway, also being a potential prognosis marker [2]. Mutations in TIMM50 cause severe mitochondrial dysfunction, leading to morphological and ultrastructural defects in mitochondria, reduced levels of OXPHOS complexes and supercomplexes, and decreased maximum respiratory capacity [3]. Patient fibroblasts with TIMM50 mutations show decreased mitochondrial membrane potential, impaired protein import, reduced respiration, and increased ROS production [4]. In TIMM50-associated mitochondrial disease, pathogenic variants reduce the levels and activity of the TIM23 complex, impacting the mitochondrial proteome and causing combined OXPHOS defects and changes in mitochondrial ultrastructure [5]. In mouse neurons, TIMM50 knockdown leads to declined respiration rates, reduced cellular ATP levels, defective mitochondrial trafficking, and increased electrical activity, potentially contributing to the neurological phenotypes seen in patients with TIMM50-related diseases [6,7]. Downregulation of TIMM50 can trigger cellular senescence through impaired mitochondrial function, while overexpression slows senescence onset [8].

In conclusion, TIMM50 is essential for mitochondrial function, with its proper function being crucial for cell survival, especially in oxidative phosphorylation-dependent conditions. Its dysregulation or mutation is associated with various diseases, including cancers, mitochondrial diseases, and potentially neurodegenerative-like phenotypes. Studies on TIMM50, including those using loss-of-function models, have enhanced our understanding of the role of mitochondrial protein import in disease mechanisms, providing potential targets for diagnosis and treatment.

References:

1. Sun, Bo, Wang, Jun, Zhu, Yan-Feng, He, Zhi-Gang, Gu, Xiao-Dong. 2020. Prognostic value of TIMM50 expression in colorectal cancer. In Archives of medical science : AMS, 19, 626-632. doi:10.5114/aoms.2020.94487. https://pubmed.ncbi.nlm.nih.gov/37313191/

2. Zhang, Xiupeng, Han, Shuai, Zhou, Haijing, Li, Ailin, Miao, Yuan. 2019. TIMM50 promotes tumor progression via ERK signaling and predicts poor prognosis of non-small cell lung cancer patients. In Molecular carcinogenesis, 58, 767-776. doi:10.1002/mc.22969. https://pubmed.ncbi.nlm.nih.gov/30604908/

3. Tort, Frederic, Ugarteburu, Olatz, Texidó, Laura, García-Silva, María Teresa, Ribes, Antonia. 2019. Mutations in TIMM50 cause severe mitochondrial dysfunction by targeting key aspects of mitochondrial physiology. In Human mutation, 40, 1700-1712. doi:10.1002/humu.23779. https://pubmed.ncbi.nlm.nih.gov/31058414/

4. Reyes, Aurelio, Melchionda, Laura, Burlina, Alberto, Ghezzi, Daniele, Zeviani, Massimo. . Mutations in TIMM50 compromise cell survival in OxPhos-dependent metabolic conditions. In EMBO molecular medicine, 10, . doi:10.15252/emmm.201708698. https://pubmed.ncbi.nlm.nih.gov/30190335/

5. Crameri, Jordan J, Palmer, Catherine S, Stait, Tegan, Frazier, Ann E, Stojanovski, Diana. 2024. Reduced Protein Import via TIM23 SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial Disease. In Molecular and cellular biology, 44, 226-244. doi:10.1080/10985549.2024.2353652. https://pubmed.ncbi.nlm.nih.gov/38828998/

6. Paz, Eyal, Jain, Sahil, Gottfried, Irit, Ashery, Uri, Azem, Abdussalam. 2024. Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein TIMM50. In eLife, 13, . doi:10.7554/eLife.99914. https://pubmed.ncbi.nlm.nih.gov/39680434/

7. Paz, Eyal, Jain, Sahil, Gottfried, Irit, Ashery, Uri, Azem, Abdussalam. 2024. Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein TIMM50. In bioRxiv : the preprint server for biology, , . doi:10.1101/2024.05.20.594480. https://pubmed.ncbi.nlm.nih.gov/38826427/

8. Nepalia, Amrita, Saini, Deepak Kumar. 2025. Ameliorating TIMM50 Loss Slows Senescence by Improving Mitochondrial Structure and Function. In Advanced biology, , e2400597. doi:10.1002/adbi.202400597. https://pubmed.ncbi.nlm.nih.gov/40128440/