Scientists at Boston Children’s Hospital demonstrate that engineered telomerase RNA (eTERC) with a specialized 5' cap and 3' protective methyladenosine tail significantly enhances telomere maintenance and lifespan of induced pluripotent stem cells from patients with telomere biology disorders. Using TENT4B-mediated methylation for stabilization, eTERC treatment forestalls senescence and restores telomere length, highlighting its translational promise for regenerative medicine applications.
Key points
Design of eTERC combining a trimethylguanosine 5′ cap and TENT4B-mediated 2′-O-methyladenosine 3′ tail for RNA stabilization.
Single transfection of eTERC restores telomerase activity and extends telomeres in TERC-null and patient-derived iPSCs, measured by TRAP and TRF assays.
eTERC treatment forestalls cellular senescence and enhances replicative lifespan in dyskeratosis congenita iPSCs and primary CD34+ HSPCs.
Why it matters:
This enzymatically stabilized telomerase RNA offers a versatile therapeutic strategy to reverse telomere attrition in degenerative telomere disorders.
Q&A
What is the role of the 3′-O-methyladenosine tail?
How does the trimethylguanosine cap improve RNA stability?
Why use induced pluripotent stem cells (iPSCs)?
What delivery challenges exist for eTERC in vivo?
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Academy
Telomerase and Its Role in Aging
Telomeres are repetitive DNA sequences capping the ends of chromosomes, protecting genomic integrity during cell division. Each time a cell divides, telomeres shorten, eventually triggering DNA damage responses and cellular senescence when critically short. Telomerase, a ribonucleoprotein enzyme, counteracts this shortening by adding telomeric repeats back onto chromosome ends. In most adult somatic cells, telomerase activity is low or absent, leading to progressive telomere erosion over time. Telomerase consists of two core components: the telomerase reverse transcriptase (TERT), which catalyzes DNA synthesis, and the telomerase RNA component (TERC), which serves as the template for new telomeric DNA synthesis.
Mechanism of Telomerase Action
- Recruitment: Telomerase is recruited to the telomere by proteins in the shelterin complex, such as TPP1 and POT1, which recognize telomeric DNA.
- Primer Alignment: The 3′ end of the chromosome aligns with the template region of TERC.
- Reverse Transcription: TERT synthesizes DNA repeats using the TERC template, elongating the telomere.
- Translocation: Telomerase realigns for additional repeat addition if needed, before dissociating from the DNA.
In stem cells, germ cells, and many cancers, telomerase is active, supporting long-term proliferation. However, mutations in telomerase components or regulatory factors cause telomere biology disorders, such as dyskeratosis congenita, leading to bone marrow failure, pulmonary fibrosis, and other degenerative phenotypes.
Synthetic Telomerase RNA Engineering
Traditional gene therapies deliver TERT or TERC genes via viral vectors, raising safety concerns. Engineering the RNA component directly as synthetic molecules provides an alternative. Key modifications include:
- 5′ Trimethylguanosine Cap: Mimics the natural cap found on endogenous TERC, enhancing binding to nuclear processing machinery and reducing innate immune activation.
- 3′ 2′-O-Methyladenosine Tail: Added enzymatically by TENT4B, this methyladenosine extension protects the RNA from exonucleases, increasing half-life in the cytoplasm.
- Self-Limiting Tailing: TENT4B incorporates a precise number of modified nucleotides before dissociating, avoiding uncontrolled elongation.
When delivered to patient-derived induced pluripotent stem cells (iPSCs) through electroporation or lipid nanoparticles, engineered TERC (eTERC) reconstitutes telomerase activity, elongates telomeres, and prevents premature senescence. This modular approach allows rapid synthesis and screening of RNA variants for optimal activity and safety.
Implications for Longevity Science
By stabilizing telomerase RNA without genomic integration, eTERC offers a flexible, non-viral strategy to restore telomere maintenance in genetic and degenerative telomere disorders. Future directions include optimizing delivery vehicles for in vivo applications, combining eTERC with TERT mRNA or protein for synergistic effects, and evaluating long-term safety in preclinical models. This work exemplifies how RNA engineering can unlock new frontiers in regenerative medicine and healthy aging research.
