Abstract
Proteolysis targeting chimeric small molecules (PROTACs) offer a strategy for degrading disease-associated proteins or controlling engineered protein tags fused to therapeutic proteins, like chimeric antigen receptors (CARs). New approaches are needed that allow spatiotemporal control of PROTAC activity, restricting degrader activity to targeted cells. Photopharmacology offers a solution by enabling light-mediated spatial control of drug action. Here, we synthesize photocaged and photoswitchable PROTAC molecules and test their regulation of proteins tagged with E. coli dihydrofolate reductase (eDHFR) in tumor and CAR-T cells. Several of the molecules are derived from triazole-linked trimethoprim-PROTACs (TMP-TACtz), that degrade eDHFR fused proteins at picomolar…
Abstract
Proteolysis targeting chimeric small molecules (PROTACs) offer a strategy for degrading disease-associated proteins or controlling engineered protein tags fused to therapeutic proteins, like chimeric antigen receptors (CARs). New approaches are needed that allow spatiotemporal control of PROTAC activity, restricting degrader activity to targeted cells. Photopharmacology offers a solution by enabling light-mediated spatial control of drug action. Here, we synthesize photocaged and photoswitchable PROTAC molecules and test their regulation of proteins tagged with E. coli dihydrofolate reductase (eDHFR) in tumor and CAR-T cells. Several of the molecules are derived from triazole-linked trimethoprim-PROTACs (TMP-TACtz), that degrade eDHFR fused proteins at picomolar concentrations, show degradation in cells with low cereblon E3 ligase levels, and have little off-target effects. The photocleavable compound, TMP-TAC-PC yields the best light-mediated regulation of CAR T cell cytotoxicity and cytokine secretion. This work introduces photocontrolled, tag-directed degraders for controlling protein expression in tumor cells and CAR T cells.
Data availability
All additional data supporting the findings of this study are available in the Supplementary Information and Source Data files. Source data are provided with this paper.
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Acknowledgements
M.A.S. is supported by the Burroughs Wellcome Fund CAMS Award, NIH Office of the Director Early Independence Award (DP5-OD26386), and NIH R01GM150804. M.A.S. is a CRI Lloyd J. Old STAR (CRI5589). D.T. is supported by NIH R01GM126228. The authors would like to thank the UPenn Flow Cytometry Core Facility as well as the Burslem Lab.
Author information
Authors and Affiliations
Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
Nitika Sharma, Swarbhanu Sarkar, Kimberly J. Edwards, Jonathan M. Pham, Tommy Nguyen, Angela Z. Gong & Mark A. Sellmyer 1.
Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
Tongil Ko, Joseph Flores & Dirk Trauner 1.
The Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
Mark A. Sellmyer
Authors
- Nitika Sharma
- Swarbhanu Sarkar
- Tongil Ko
- Kimberly J. Edwards
- Jonathan M. Pham
- Tommy Nguyen
- Angela Z. Gong
- Joseph Flores
- Dirk Trauner
- Mark A. Sellmyer
Contributions
N.S. performed the in vitro studies (tumor and FAP CAR-eDHFR T cells), synthesized of TMP-TACtz-1-4, photocaged compound TMP-TAC-PC, and photoswitch TMP-TAC-PS-2; SS synthesized photoswitches TMP-TAC-PS-1, 3-5; T.K. performed photophysical studies and provided photoswitch building blocks, T.N. performed western blots, K.J.E. generated FAP CAR-eDHFR T cells, J.P. performed ELISAs, J.P. and A.G. generated and performed CD19 CAR eDHFR-T cells studies, J.F. performed PSS study. M.A.S. and D.T. supervised the project. N.S. wrote the first draft of the manuscript, and all authors contributed to the final manuscript.
Corresponding authors
Correspondence to Dirk Trauner or Mark A. Sellmyer.
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Competing interests
The University of Pennsylvania has filed IP (US20240226100A1/WO2022217295A1) on TMP derivative PROTACs on which NS and MAS are inventors. M.A.S. is scientific co-founder and equity holder for Vellum Biosciences, a company commercializing TMP-related imaging agents and regulatory strategies. The remaining authors declare no competing interests.
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Sharma, N., Sarkar, S., Ko, T. et al. Photocontrolled trimethoprim PROTACs targeting the eDHFR protein tag. Nat Commun (2025). https://doi.org/10.1038/s41467-025-67527-5
Received: 10 January 2025
Accepted: 27 November 2025
Published: 27 December 2025
DOI: https://doi.org/10.1038/s41467-025-67527-5