Biology subjects

Adams, S. R.

Publications and source records attributed to Adams, S. R..

7 recordsLinked to original sources

bioRxiv2026

Orthogonally targeted tumor radiosensitization using cell penetrating peptide-ATM inhibitor conjugates to stimulate anti-tumor immune responses

Tumor resistance to radiotherapy continues to be a significant problem in improving cancer patient outcomes. To overcome radioresistance, drugs that sensitize cancer cells to ionizing radiation have been tested. In theory, radiosensitizers should increase irradiated tumor kill and improve patient outcomes. In practice, the clinical utility of such drugs is curtailed by radiosensitization of peri-tumoral normal tissues causing toxicities. To address these issues, we developed an activatable cell penetrating peptide-drug conjugate to deliver a small molecule radiosensitizer with spatial precision to tumors. The activatable cell penetrating peptide (ACPP) scaffold cloaks a cell penetrating peptide-drug conjugate until it is unmasked within tumors through matrix metalloproteinase cleavage. Using antibody-drug conjugate linker chemistry, we attached the potent ataxia-telangiectasia mutated (ATM) kinase inhibitor AZD0156 to ACPP and created ACPP-AZD0156. In immune-competent murine cancer models, tumor-targeted ACPP-AZD0156 in combination with ionizing radiation stimulated tumor immune infiltration by CD8+ T cells and increased tumor control when compared to non-targeted ATM inhibitor. Mechanistically, ACPP-AZD0156 radiosensitized tumor control was dependent on the adaptive arm of the immune system. Finally, the combination of radiotherapy and ACPP-AZD0156 potentiated immune checkpoint inhibitors that resulted in durable tumor control. The therapeutic synergies of ACPP targeted ATM inhibitor to radiosensitize and stimulate anti-tumor immune responses provides a rationale for developing tumor-targeted radiosensitizer drug conjugates that restrict radiosensitization to cancer cells that then engages anti-tumor immune responses to improve cancer patient outcomes.

pharmacology and toxicology↗

bioRxiv2025

ColorSTEM: An easy and convenient approach to Multicolor Electron Microscopy of Labeled Biological Specimens

A new method for Multicolor Electron Microscopy (EM) using scanning transmission EM, ColorSTEM has been developed to increase the sensitivity, instrument availability and ease of use compared to that previously developed using electron energy loss spectroscopy and energy filtered transmission EM. Both methods paint multiple subcellular complexes with different colors, enabled by the localized and targeted deposition of diaminobenzidine (DAB) conjugated to different metals, which provides the differentiating signal from each other. With ColorSTEM, elastic scattering that is dependent upon atomic weight (Z-contrast) has far greater signals. Using deposited DAB with copper or gold to label subcellular components, Z-contrast imaging generates a pseudo-elemental map, resulting from differences in the grayscale of the conventional STEM images.

cell biology↗

bioRxiv2024

Directed evolution of the multicopper oxidase laccase for cell surface proximity labeling and electron microscopy

Enzymes that oxidize aromatic substrates have shown utility in a range of cell-based technologies including live cell proximity labeling (PL) and electron microscopy (EM), but are associated with drawbacks such as the need for toxic H2O2. Here, we explore laccases as a novel enzyme class for PL and EM in mammalian cells. LaccID, generated via 11 rounds of directed evolution from an ancestral fungal laccase, catalyzes the one-electron oxidation of diverse aromatic substrates using O2 instead of toxic H2O2, and exhibits activity selective to the surface plasma membrane of both living and fixed cells. We show that LaccID can be used with mass spectrometry-based proteomics to map the changing surface composition of T cells that engage with tumor cells via antigen-specific T cell receptors. In addition, we use LaccID as a genetically-encodable tag for EM visualization of cell surface features in mammalian cell culture and in the fly brain. Our study paves the way for future cell-based applications of LaccID.

biochemistry↗

bioRxiv2023

Fe-TAMLs as a new class of small molecule peroxidase probes for correlated light and electron microscopy

We introduce Fe-TAML, a small molecule-based peroxidase as a versatile new member of the correlated fluorescence and electron microscopy toolkit. The utility of the probe is demonstrated by high resolution imaging of newly synthesized DNA (through biorthogonal labeling), genetically tagged proteins (using HaloTag), and untagged endogenous proteins (via immunostaining). EM visualization in these applications is facilitated by exploiting Fe-TAMLs catalytic activity for the deposition of localized osmiophilic precipitates based on polymerized 3,3-diaminobenzidine. Optimized conditions for synthesizing and implementing Fe-TAML based probes are also described. Overall, Fe-TAML is a new chemical biology tool that can be used to visualize diverse biomolecular species along nanometer and micron scales within cells.

cell biology↗

bioRxiv2023

Proximal Molecular Probe Transfer (PROMPT), a new approach for identifying sites of protein/nucleic acid interaction in cells by correlated light and electron microscopy

The binding and interaction of proteins with nucleic acids such as DNA and RNA constitutes a fundamental biochemical and biophysical process in all living organisms. Identifying and visualizing such temporal interactions in cells is key to understanding their function. To image sites of these events in cells across scales, we developed a method, named PROMPT for PROximal Molecular Probe Transfer, which is applicable to both light and correlative electron microscopy. This method relies on the transfer of a bound photosensitizer from a protein known to associate with specific nucleic acid sequence, allowing the marking of the binding site on DNA or RNA in fixed cells. The method produces a fluorescent mark at the site of their interaction, that can be made electron dense and reimaged at high resolution in the electron microscope. As proof of principle, we labeled in situ the interaction sites between the histone H2B and nuclear DNA. As an example of application for specific RNA localizations we labeled different nuclear and nucleolar fractions of the protein Fibrillarin to mark and locate where it associates with RNAs, also using electron tomography. While the current PROMPT method is designed for microscopy, with minimal variations, it can be potentially expanded to analytical techniques.

cell biology↗

bioRxiv2020

Elemental Mapping of Labeled Biological Specimens at Intermediate Energy Loss in an Energy-Filtered TEM acquired using a Direct Detection Device

The multi-color or single-color EM that was developed previously, by the pseudo-colored overlay of the core-loss or high-loss EFTEM elemental map/s of the lanthanide onto the conventional image, the lanthanide chelates conjugated to diaminobenzidine being sequentially deposited as a result of selective oxidization by orthogonal photosensitizers / peroxidases. The synthesis of the new second generation lanthanide DABs, which contains 4 times more lanthanide per DAB, gives significant signal amplification and enabling collection of elemental maps at much lower energy-loss regions more favorable. Under the same experimental conditions, acquiring EFTEM elemental maps for the lanthanides at the lower energy-loss of N4,5 edge instead of the core-loss M4,5 edge, provides ~4x increase in signal-to-noise and ~2x increase in resolution. The higher signal at the N4,5 edge, also allows for more sophisticated technique of EFTEM spectrum Image for the acquisition of elemental maps with very high signal fidelity.

systems biology↗

bioRxiv2018

Split-miniSOG for detecting and localizing intracellular protein-protein interactions: application to correlated light and electron microscopy

A protein complementation assay (PCA) for detecting and localizing intracellular protein-protein interactions (PPIs) was built by bisection of miniSOG, a fluorescent flavoprotein derived from the light, oxygen, voltage (LOV)-2 domain of Arabidopsis phototropin. When brought together by interacting proteins, the fragments reconstitute a functional reporter that permits tagged protein complexes to be visualized by fluorescence light microscopy (LM), and then by standard as well as \"multicolor\" electron microscopy (EM) imaging methods via the photooxidation of 3-3-diaminobenzidine (DAB) and its lanthanide-conjugated derivatives.

cell biology↗