Summary: A new study identifies a key contributor to brain aging and Alzheimer’s disease: the accumulation of Glu-5′tsRNA-CTC, a small tRNA-derived fragment, inside neuronal mitochondria. This fragment interferes with mitochondrial protein synthesis and damages cristae architecture, accelerating cognitive decline and Alzheimer’s-related pathology.
By using antisense oligonucleotides to target these tRNA fragments in aged mice, researchers reversed memory deficits, pointing to a promising therapeutic approach. The findings emphasize the central role of mitochondrial dysfunction in neurodegeneration and suggest new directions for preventing or treating age-related cognitive decline.
Key Facts:
- Glu-5′tsRNA-CTC accumulates in neuronal mitochondria with age and disrupts critical components of mitochondrial translation and cristae organization.
- Targeting Glu-5′tsRNA-CTC with antisense oligonucleotides (ASOs) rescues learning and memory deficits in aged mice.
- The work highlights the importance of preserved mitochondrial cristae and glutamate metabolism for maintaining synaptic function and cognitive health during aging.
Source: University of Science and Technology of China
A major paper published in Cell Metabolism by Professor LIU Qiang’s team at the University of Science and Technology of China (USTC) reveals how glutamate tRNA fragments contribute to brain aging and Alzheimer’s disease.
The researchers report an age-dependent increase of Glu-5′tsRNA-CTC, a transfer-RNA-derived small RNA (tsRNA) originating from nuclear-encoded tRNAGlu, which accumulates within the mitochondria of glutamatergic neurons.
This abnormal accumulation impairs mitochondrial translation and alters cristae structure, processes that are essential for proper mitochondrial function and neuronal energy production. As a result, the study links tsRNA accumulation to accelerated brain aging and worsening Alzheimer’s-like pathology.
Brain aging is a universal process characterized by gradual loss of cognitive abilities, and Alzheimer’s disease is the most common cause of dementia in older adults. Growing evidence implicates mitochondrial dysfunction as a major driver of both the aging process and neurodegenerative disease.
Mechanistically, the study shows that mitochondrial Glu-5′tsRNA-CTC interferes with the interaction between mitochondrial tRNALeu (mt-tRNALeu) and leucyl-tRNA synthetase 2 (LARS2). This disruption reduces mt-tRNALeu aminoacylation, impairing the translation of mitochondria-encoded proteins.
Defects in mitochondrial translation then lead to disrupted cristae architecture. Because cristae structure supports enzymes such as glutaminase (GLS), damaged cristae result in reduced GLS-dependent glutamate synthesis and lower synaptic glutamate levels—factors that undermine synaptic transmission and cognitive function.
Importantly, lowering Glu-5′tsRNA-CTC levels protects aged brains from several age-related deficits: it preserves cristae morphology, supports glutamine and glutamate metabolism, maintains synaptic integrity, and rescues memory performance in animal models.
To test therapeutic potential, the authors designed antisense oligonucleotides targeting Glu-5′tsRNA-CTC and administered them into the brains of aged mice. This targeted intervention significantly improved learning and memory outcomes, demonstrating that modulation of specific tsRNAs can reverse cognitive decline linked to mitochondrial dysfunction.
Beyond clarifying how normal cristae ultrastructure maintains glutamate homeostasis, this study defines a pathological role for tRNA-derived fragments in brain aging and age-related memory loss. By connecting molecular events in mitochondria to synaptic and cognitive deficits, the research provides a concrete pathway for developing mitochondrial-targeted therapies for Alzheimer’s disease and related disorders.
About this Alzheimer’s disease research news
Author: Jane Fan
Source: University of Science and Technology of China
Contact: Jane Fan – University of Science and Technology of China
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Aging-induced tRNAGlu-derived fragment impairs glutamate biosynthesis by targeting mitochondrial translation-dependent cristae organization” by Dingfeng Li et al., Cell Metabolism
Abstract
Aging-induced tRNAGlu-derived fragment impairs glutamate biosynthesis by targeting mitochondrial translation-dependent cristae organization
Highlights
- Aging promotes cytoplasmic localization of angiogenin, producing Glu-5′tsRNA-CTC.
- Glu-5′tsRNA-CTC impairs mitochondrial translation and alters cristae organization.
- Intact cristae ultrastructure is essential to maintain glutamate homeostasis in the brain.
- ASOs targeting Glu-5′tsRNA-CTC rescue age-related memory decline in mice.
Summary
Mitochondrial cristae—folded structures of the mitochondrial inner membrane—become progressively disorganized with age. The molecular drivers of this change and their contribution to brain aging have been unclear.
This study documents an age-dependent accumulation of Glu-5′tsRNA-CTC, a tsRNA derived from nuclear-encoded tRNAGlu, within mitochondria of glutamatergic neurons. Mitochondrial Glu-5′tsRNA-CTC disrupts the binding between mt-tRNALeu and leucyl-tRNA synthetase 2 (LARS2), compromising mt-tRNALeu aminoacylation and the translation of mitochondrially encoded proteins.
These translation defects alter cristae organization, which in turn impairs GLS-dependent glutamate production and reduces synaptosomal glutamate content. Reducing Glu-5′tsRNA-CTC in aged brains restores cristae structure, glutamate metabolism, synaptic architecture, and memory function.
Overall, the findings reveal a pathological mechanism linking tsRNA accumulation to mitochondrial dysfunction and cognitive decline, and they identify a potential therapeutic strategy to mitigate brain aging and Alzheimer’s-related cognitive impairment.