# Engineering Anti-Tau Intrabodies that Reduce Tauopathy by Either the Proteasome, Lysosome, or Chaperone Mediated Autophagy

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 2021 · $393,750

## Abstract

Project Summary/Abstract
The accumulation of pathological tau is the main component of neurofibrillary tangles in Alzheimer’s disease and
several degenerative diseases, referred to as tauopathies. We previously found that administration of an anti-
tau antibody to human tau (h-tau) or expression of an anti-tau secreted single-chain variable fragment (scFv) in
the central nervous system (CNS) of h-tau transgenic mice (P301S-tg) decreased but did not remove all tau-
associated pathology. While these and other studies demonstrate immunotherapeutic approaches targeting tau
can influence tau pathogenesis, conventional immunotherapeutic approaches present some limitations that
preclude their full potential when targeting tauopathy. Including, immunotherapy is limited to targeting
extracellular proteins whereas the majority of pathological tau remains in the cytosol of cells, not typically
accessible to an extracellular antibody or secreted scFv. In addition, a significant limitation of passive
immunization is the necessity for chronic administration of antibodies of which only a small % (0.1-0.2%) cross
the blood-brain-barrier (BBB). When translated into humans, this may be limited by manufacturing. To potentially
overcoming these limitations, we hypothesize the expression of anti-tau scFv in the cytosol of neurons
(intrabodies) will reduce tauopathy with improved efficacy. To enhance the ingenuity of conventional intrabodies,
we have engineered chimeric anti-tau intrabodies fused to ubiquitin harboring distinct mutations or containing a
heat-shock motif (HSC) with the goal of shuttling intracellular tau for degradation by either the proteasome,
lysosome or chaperone-mediated autophagy (CMA). In preliminary data, expressing the modified anti-tau
intrabodies in primary neuronal cultures expressing h-tau reduced h-tau protein levels. Moreover, the expression
of the modified anti-tau intrabodies in aged P301S-tg mice after disease onset effectively reduced tauopathy
whereas; a conventional anti-tau intrabody containing no tags was ineffective in reducing tauopathy. The goals
for this project are to validate the degradation mechanisms by which the anti-tau intrabodies reduce tau levels
and determine the extent to which anti-tau intrabodies prevent or stop tauopathy. In addition, we aim at bypass
the BBB by combining our anti-tau intrabodies with the recent advances in adeno-associated virus-mediated
gene transfer that provide global-neuronal transduction in the adult mouse CNS by intravenous administration.
We further propose to generate new anti-tau intrabodies that target aberrant phosphorylated tau sites, which
may display an enhanced efficacy by selectively degrading pathological tau. The current proposal harnessed the
strength of intrabodies, which are amendable for targeting specific domains or modifications with the cell-intrinsic
mechanisms that regulate protein degradation potentially providing a new immunotherapeutic agent with
improved efficacy.

## Key facts

- **NIH application ID:** 10151552
- **Project number:** 5R01AG063817-03
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Gilbert Gallardo
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $393,750
- **Award type:** 5
- **Project period:** 2019-08-01 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10151552

## Citation

> US National Institutes of Health, RePORTER application 10151552, Engineering Anti-Tau Intrabodies that Reduce Tauopathy by Either the Proteasome, Lysosome, or Chaperone Mediated Autophagy (5R01AG063817-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10151552. Licensed CC0.

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