# De Novo Engineering of Small Molecule-Actuatable Biosensors for Cell Therapy

> **NIH NIH R35** · UNIVERSITY OF WASHINGTON · 2020 · $390,679

## Abstract

De Novo Engineering of Small Molecule-Actuatable Biosensors for Cell Therapy
ABSTRACT
Preceded by small-molecule drugs and biologics, cell-based therapies, such as the use of chimeric antigen
receptor T (CAR-T) cells against blood cancers, is becoming a new pillar of medicine. However, compared with
traditional drugs, they are more susceptible to safety concerns due to difficulties associated with controlling cell
actions in a therapeutic setting. My research program aims to develop a novel approach to engineer genetically
encoded biosensors for spatiotemporal control of cell behaviors. We focus on the de novo engineering of the
biosensors for using small molecules to control cell therapeutic responses, proliferation, death, migration,
communication, and metabolism. Our strategy is to design chemically induced dimerization (CID) systems,
in which two proteins dimerize only in the presence of a small molecule. To date, only a few CID systems are
available and their dimerization inducers are not ideal for clinical use. The de novo design of CID systems with
desired affinity and specificity for given small molecules remains an unsolved problem in the field of protein
engineering. We will solve this problem by coupling computational protein design to our recently developed
single-molecular-interaction sequencing (SMI-seq) technology. SMI-seq has the potential to break a key
barrier to CID engineering by enabling large-scale, two-dimensional (or ‘library-by-library’) screening of two
CID binder variant libraries. We will apply two parallel approaches to engineer CID systems: i) targeted
screening of computationally designed binder libraries, and ii) random screening of vastly diverse combinatorial
binder libraries (>109) using immunoglobulin or de novo designed scaffolds. We will assess the success rates,
turnaround times, and cost-effectiveness of both approaches by testing a set of clinically approved antiviral
drugs with excellent intracellular delivery efficiency as CID inducers. Finally, we will demonstrate the use of
designed biosensors to control cellular processes in both cultured cells and a mouse model. Successful
completion of this research will open up new possibilities for engineering ligand-responsive protein assemblies,
an unexplored territory of protein design. Designed CID systems will significantly expand the chemogenetic
toolkit for gene- and cell-based therapies, as well as systems and synthetic biology research.

## Key facts

- **NIH application ID:** 9984445
- **Project number:** 5R35GM128918-03
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Liangcai Gu
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $390,679
- **Award type:** 5
- **Project period:** 2018-08-01 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9984445

## Citation

> US National Institutes of Health, RePORTER application 9984445, De Novo Engineering of Small Molecule-Actuatable Biosensors for Cell Therapy (5R35GM128918-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9984445. Licensed CC0.

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