Jumping Genes

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Recent research by University of Texas (UT) Health San Antonio has found that transposon activation may be a key factor in the progression of Alzheimer’s disease.

Jumping Genes and Alzheimer’s

• Jumping genes, scientifically known as transposons, are mobile genetic elements that can move from one location to another within the genome. They were first discovered by Barbara McClintock, who won the Nobel Prize in 1983 for this work.
• In humans, transposons make up nearly 50% of the genome, and while most are inactive, some retain the ability to “jump” and cause genomic instability.
• The most common type of jumping genes is retrotransposons, especially LINE-1 elements, which replicate through an RNA intermediate and use reverse transcriptase to reintegrate into DNA.
• Normally, the activity of these elements is tightly controlled by the body through epigenetic mechanisms, but in aging or diseased brains, especially in neurodegenerative conditions like Alzheimer’s, these controls can weaken.
• Once activated, transposons can insert themselves into essential genes, disrupt DNA sequences, and lead to cellular damage, especially in the brain’s neurons, which are non-dividing and highly vulnerable.
• In experiments with genetically modified fruit flies that mimic Alzheimer’s symptoms, blocking transposon activity using an HIV drug (3TC) led to improvements in neural function.
  • 3TC is a reverse transcriptase inhibitor, which prevents retrotransposons from copying and inserting themselves into new parts of the genome.
  • In a clinical trial with human patients, 3TC did not directly improve memory but reduced neurofilament light (NfL)—a key biomarker of neurodegeneration—suggesting protection against neuronal damage.
• This supports a new hypothesis: Alzheimer’s disease may not just be a disorder of protein aggregation (like amyloid or tau), but also one of genomic instability caused by the reactivation of jumping genes.

Source: SC

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