January 23, 2018
11 am to 12 pm ET
Biotechnology promises the ability to control biology and disease with laser-like precision, but biomolecules typically have poor cell penetration and unpredictable subcellular localization. Hundreds of peptides, proteins and nucleic acids are being
developed as diagnostics and therapies. For many of these, intracellular delivery remains the primary obstacle. Currently, there are no quantitative, high-throughput tools to measure how much of a biomolecule enters a cell and where it distributes
within the cell. Importantly, most widely-used methods for measuring cell penetration cannot rule out effects of material at the cell surface or trapped in endosomes.
We have devised a chloroalkane penetration assay (CAPA) that exclusively measures penetration to the cytoplasm. CAPA uses a cell line with stably expressed HaloTag in the cytoplasm, and measures the extent of covalent reaction between this enzyme
and a small chloroalkane tag appended to the molecule of interest. The CAPA readout is fast, inexpensive, and high-throughput, enabling the rapid determination of structure-activity relationships for extent of cell penetration, independent of
the molecule’s cellular phenotype. We are also producing CAPA cell lines for quantitating penetration into other compartments and organelles, and testing its compatibility with a wide range of bioactive molecules and drug delivery systems.
CAPA will enable rapid progress in understanding and promoting cytosolic penetration for a variety of biomolecules and drug delivery technologies.
- Challenges of measuring cell penetration and subcellular localization of biomolecules
- Chloroalkane Penetration Assay (CAPA) for measuring penetration to the cytoplasm
- Rapidly determining SAR relationships for cell penetration, independent of the molecule’s cellular phenotype
- Current and future applications of CAPA for understanding cytosolic penetration of biomolecules and quantitatively comparing drug delivery technologies
Department of Chemistry
Joshua Kritzer is an Associate Professor in the Department of Chemistry at Tufts University. The Kritzer lab solves foundational problems in drug discovery using methods from synthetic chemistry, biophysics, biochemistry, structural biology, genetics
and cell biology. Dr. Kritzer’s focus on problems of broad biomedical interest have been recognized with appointments as members of the Molecular Microbiology Program and the Cell, Molecular and Developmental Biology Program at Tufts University’s
Sackler School of Graduate Biomedical Sciences. Dr. Kritzer was also a founding member of a privately-funded consortium, the Raymond and Beverly Sackler Convergence Laboratory, which works on problems that require the convergence of multiple fields
of science. Dr. Kritzer’s high-impact research and innovative teaching have been recognized with several awards, including the Smith Family Award for Excellence in Biomedical Research and an NIH New Innovator Award.