Biology subjects

Tennakoon, R.

Publications and source records attributed to Tennakoon, R..

4 recordsLinked to original sources

bioRxiv2026

Impact of Realistic 3D Tumor Microarchitecture on Cellular Dosimetry and Radiobiological Response in Targeted Radionuclide Therapy

Background: Patient-specific dosimetry in targeted radionuclide therapy (TRT) is increasingly supported by quantitative imaging; however, voxel-scale dose estimates cannot resolve cellular and subcellular heterogeneity present within tumor tissue. Conventional cellular dosimetry models often represent cells as regularly packed spheres, which may not capture realistic tumor microarchitecture. This study investigated how histopathology-informed three-dimensional (3D) tumor microarchitecture influences cellular absorbed-dose distributions, predicted radiobiological response, and treatment-related conclusions in TRT. Methods: Realistic 3D cellular tumor models were constructed from thick-section 3D cyclic immunofluorescence (3D CyCIF) imaging data. Monte Carlo radiation-transport simulations were performed for Lu-177, Pd-103, Tb-161 and Y-90, with activity localized in cancer-cell subcellular compartments and in non-cancer targets. Absorbed dose per total cluster decay was calculated individually for each cell nucleus and compared with corresponding simplified spherical tumor models. Cell survival fractions were estimated using the linear-quadratic model, and tumor control probability (TCP) was calculated from the individual cancer-cell survival probabilities. Results: Simplified model overestimated mean cancer-cell nuclear absorbed dose by 9.54% to 14.51% for nuclear localization and by 33.23% to 44.88% for cytoplasmic and membrane localization. In larger tissue models, simplified and realistic geometries produced comparable mean absorbed doses in several cases; however, the realistic models consistently generated broader cellular dose distributions, including low-dose cancer-cell subpopulations not captured by the simplified models. These dose-distribution differences propagated into wider survival-fraction distributions and altered TCP predictions. In the spatially heterogeneous tumor region, the realistic model required 1.11- to 1.33-fold higher activity to reach TCP90 for nuclear localization, and 1.49- to 5.93-fold higher activity for cytoplasmic and membrane localization. For similar tumor control, the radionuclide and source-localization combination associated with the greatest preservation of surrounding non-cancer cells differed between the simplified and realistic models. The intra-voxel analysis further showed that homogeneous voxel-scale activity assumptions can obscure biologically relevant microscopic dose heterogeneity. Conclusion: Native 3D tumor microarchitecture substantially influences cellular absorbed-dose distributions, predicted biological response, and treatment-related conclusions. Histopathology-informed 3D cellular models can be used as a complementary framework for characterizing cellular dose heterogeneity and may improve the evaluation of radionuclides and subcellular targeting strategies in heterogeneous tumor tissue.

cancer biology↗

bioRxiv2026

A Metabolic Labeling Strategy for Tracking Protein Synthesis in Complex Biological Systems

Protein synthesis supports most biological processes. In the brain in particular, protein synthesis plays a critical role in physiological and pathological states. Here, we describe Tellurophene-Alkyne Cycloaddition-mediated Amino acid Tagging (TeACAT), a versatile strategy for fast, facile, and flexible tagging of newly synthesized proteins in mice. TeACAT is based on metabolic incorporation of the non-canonical amino acid TePhe into proteins by the endogenous protein synthesis machinery. Due to their high similarity, TePhe can efficiently replace canonical Phe without dietary or genetic manipulation. The subsequent bio-orthogonal reaction of TePhe with either fluorescent dyes or affinity handles enables both visualization and affinity enrichment of proteins synthesized during TePhe exposure. TeACAT is compatible with immunofluorescence for cell-type specific visualization of protein synthesis with subcellular resolution and can be used in conjunction with routine proteomics to identify and quantify newly synthesized proteins. Robust incorporation into the mouse proteome was observed on the scale of hours to days, allowing the interrogation of various biological processes. In summary, TeACAT enables the visualization and quantification of protein synthesis with minimal perturbation for biological discoveries.

molecular biology↗

bioRxiv2025

RARS1 integration into the multisynthetase complex is crucial for mammalian brain development

Aminoacyl tRNA synthetases occupy a central role in protein synthesis by charging tRNAs with their cognate amino acid. Eight aminoacyl-tRNA synthetases with nine enzymatic activities form a large protein complex but the breadth of functions mediated by the multisynthetase complex remains elusive. Neurological disorders have been associated with mutations within the domain tethering Arginyl-tRNA synthetase (RARS1) to the multisynthetase complex, which offers an interesting bridge between protein synthesis and neurodevelopment. To interrogate this connection, we developed a mouse model where RARS1 is excluded from the multisynthetase complex in the forebrain. We observed profound disruptions in neural development as attested by drastically reduced forebrain size and behavioral deficits. At the molecular level, neurodevelopmental and ribosomal genes were dysregulated. Finally, the subcellular localization of RARS1 and its colocalization with other translational machinery components were perturbed. Altogether, our results reveal the necessity of RARS1 integration in the multisynthetase complex for proper neurodevelopment.

molecular biology↗

bioRxiv2025

A disease-causing Isoleucyl-tRNA synthetase variant leads to altered protein complex formation and cellular stress response

Aminoacyl-tRNA synthetases are key enzymes in protein synthesis, as they catalyze the attachment of amino acids to their designated, cognate tRNAs. As such, mutations in aminoacyl-tRNA synthetases are associated with severe diseases, such as neurodevelopmental disorders. Many of these mutations occur in the catalytically active site or tRNA binding domains, however, others can affect domains associated with multisynthetase complex formation. Here, we investigate a disease-causing mutation in the UNE-L domain of Isoleucyl-tRNA synthetase (IARS1, IleRS), which mediates IleRS interactions within the multisynthetase complex. Interestingly, levels of the resulting protein were severely reduced in comparison to wildtype IleRS. While bulk protein synthesis and cell proliferation were not affected, the integrated stress response signaling pathway was altered. This change was exacerbated in low glucose medium, suggesting that mutant cells could respond differently to cellular stress. Our study hints at a possible underlying disease mechanism, where catalytic activity might not be affected but instead complex formation and protein stability.

molecular biology↗