Mitochondrial unfolded protein response: An emerging pathway in human diseases.

Mitochondrial unfolded protein response (UPR) is a mitochondria stress response, which the transcriptional activation programs of mitochondrial chaperone proteins and proteases are initiated to maintain proteostasis in mitochondria. Additionally, the activation of UPR delays aging and extends lifespan by maintaining mitochondrial proteostasis. Growing evidences suggests that UPR plays an important role in diverse human diseases, especially ageing-related diseases. Therefore, this review focuses on the role of UPR in ageing and ageing-related neurodegenerative diseases such as Alzheimer's disease, Huntington's disease and Parkinson's disease. The activation of UPR and the high expression of UPR components contribute to longevity extension. The activation of UPR may ameliorate Alzheimer's disease, Parkinson's disease and Huntington's disease. Besides, UPR is also involved in the occurrence and development of cancers and heart diseases. UPR contributes to the growth, invasive and metastasis of cancers. UPR has paradoxical roles in heart diseases. UPR not only protects against heart damage, but may sometimes aggravates the development of heart diseases. Considering the pleiotropic actions of UPR system, targeting UPR pathway may be a potent therapeutic avenue for neurodegenerative diseases, cancers and heart diseases.