ATP-dependent liquid phase separation during aging and neurodegeneration

2023 Fiscal Year Annual Research Report

• Project/Area Number: 21K06400
• Research Institution: Okinawa Institute of Science and Technology Graduate University
• Principal Investigator: Guillaud Laurent 沖縄科学技術大学院大学, 分子神経科学ユニット, グループリーダー (90596222)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: Aging / ATP / Viscoelasticity / Liquid phase separation

Outline of Annual Research Achievements

During the last year, this project was developed into 2 parallel approaches to study and confirm the effect of aging on ATP synthesis and protein aggregation in human iPSCs and in mouse primary neurons.
1) I used human-iPSCs of different ages and showed that the intracellular level of ATP is significantly reduced in 80 y/o compared to 20 y/o iPSCs. This decrease in ATP is also associated with a reduction in cell growth and viability in 80 y/o compared to 20 y/o iPSCs. I also quantified the level of DNA methylation in both genomic and mitochondrial DNA. This observation indicated a higher level of DNA methylation in 80 y/o compared to 20 y/o iPSCs up to their 4th passage in culture.
I started to analyze the difference in cytosolic viscoelasticity in these iPSCs by fluorescence recovery after photobleaching (FRAP), and my preliminary results suggested a possible perturbation of the cytosol viscoadaption in 80 y/o iPSCs compared to 20 y/o iPSCs.
2) I also used mouse sensory neurons in primary culture from 8 weeks and 52 weeks old animals to determine their difference in ATP synthesis, number of mitochondria and axoplasmic viscoelasticity as previously described for iPSCs. Sensory neurons from 52 weeks old animal showed significant reduction in their intracellular level of ATP as well as in their axoplasmic fluidity. These data confirmed our observations in iPSCs and suggested that deficit in ATP synthesis and reduction in cytosolic fluidity are common features of aging in both mouse and human.