Scientists at the Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, have discovered a "biphasic mitochondrial molecular clock" that tracks aging across human organs. Published in Nature Aging, the research, led by Prof. LI Xin, shows mitochondria encode aging through two distinct modes, offering a new lens on why organs age at different rates.

Mitochondria, cellular powerhouses with their own fast-mutating DNA, act as aging "timers." Analyzing mitochondrial RNA from 47 tissues in 838 individuals, the team identified two aging signatures: Proliferative Tissues and Post-Mitotic Tissues.

Proliferative Tissues (e.g., skin, gut) experience a "stochastic spread" of random DNA replication errors. This accelerated accumulation of sporadic mutations contributes to age-related dysfunction and tumor risk.

Post-Mitotic Tissues (e.g., heart, brain) accumulate mutations at specific "deterministic damage hotspots". This reflects the cumulative burden of high energy demand and mitochondrial turnover, akin to "wear and tear".

"The ‘mitochondrial clock' is like equipping each organ with its own ‘aging GPS'," from Prof. Li. This biphasic model—unifying "replicative" and "metabolic" aging—could empower age-related diagnostics and therapies by providing tissue-specific insights. The work highlights vulnerabilities to age-related diseases and points to new avenues for early detection.

Age-related mitochondrial damage hotspots and mutational burden. (Image by Prof. Li’s team)

Paper link: https://doi.org/10.1038/s43587-025-00890-6

Scientific Contact:
Prof. LI Xin
Shanghai Institute of Nutrition and Health,
Chinese Academy of Sciences 
Email: lixin@sinh.ac.cn

Media Contact:
WANG Jin
Shanghai Institute of Nutrition and Health,
Chinese Academy of Sciences
Email: wangjin01@sinh.ac.cn
Web: http://english.sinh.cas.cn/