# Defining molecular contributions of LINE-1 retrotransposons to AD / ADRD

> **NIH NIH R01** · ROCKEFELLER UNIVERSITY · 2024 · $746,218

## Abstract

Project Summary: Alzheimer's Disease (AD) and AD-related dementias (ADRDs; e.g. Frontotemporal
Dementia, Lewy Body Dementia, etc.) are crippling neurodegenerative disorders. The onset of these diseases
is strongly correlated with aging. Cures for AD and ADRDs remain elusive; Alzheimer's has become the 6th most
frequent cause of death in the USA. An emerging candidate contributor to Alzheimer's and ADRD is the L1
retrotransposon, which becomes dysregulated during aging and correlates with Alzheimer's / ADRD onset. One
hypothetical mechanism by which L1 may contribute to Alzheimer's / ADRD is through its exacerbation of cellular
senescence. Senescence is a phenomenon by which normal cells stop dividing; these cells accumulate with
advancing age and are found at the locations of dysfunction in age-related diseases. In mice, senescent cells
have been shown to shorten life and actively drive age-related neurodegeneration; preventing senescent cell
accumulation decreases tau-dependent degeneration and cognitive decline. AD patients exhibit increased
indicators of cellular senescence. It is increasingly clear that senescent cells are not inert, but instead drive tissue
deterioration via the senescence-associated secretory phenotype - secreting a variety of growth factors and pro-
inflammatory cytokines. L1 retrotransposons have recently been shown to drive progression of the senescence-
associated secretory phenotype, and thus, L1 is an important agent of cellular senescence. L1 activation is also
associated with AD-related Tau pathologies. The L1 encoded ORF2p enzyme (endonuclease and reverse
transcriptase) is often flagged as a source of pathological cellular insults, e.g. via new, mutagenic L1 insertions
and contributions to chromosomal instability. However, the effects of L1 expression extend beyond DNA
damage. Numerous mechanisms may be at play, including the titration of normally homeostatic host factors
away from their physiologic functions and into L1 ribonucleoprotein granules, as well as the production of
immunity-and-inflammation-triggering cytoplasmic L1 DNA:RNA hybrids; indeed, the latter is now understood to
be a key component of L1’s role in cellular senescence. Moreover, L1 also mobilizes Alu and other non-
autonomous retrotransposons.
Objectives: In Aim 1, we will use targeted mass spectrometry to profile L1 ORF1 protein expression in the
cerebrospinal fluid (CSF) and post-mortem brain tissues of patients exhibiting AD/ADRD and cognitive decline,
as well as in senescent cells and neuronal iPSCs; in Aim 2 (in vitro cell culture) and Aim 3 (clinical samples) we
will profile L1-associated protein-protein and protein-RNA interactions in the same biological samples as Aim 1;
and in Aim 4 we will take a candidate-based approach using molecular genetics to dissect the mechanisms of
action of L1 in senescent cells.

## Key facts

- **NIH application ID:** 10840983
- **Project number:** 5R01AG078925-03
- **Recipient organization:** ROCKEFELLER UNIVERSITY
- **Principal Investigator:** John LaCava
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $746,218
- **Award type:** 5
- **Project period:** 2022-09-15 → 2027-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10840983

## Citation

> US National Institutes of Health, RePORTER application 10840983, Defining molecular contributions of LINE-1 retrotransposons to AD / ADRD (5R01AG078925-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10840983. Licensed CC0.

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