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Pichurin, J.

Publications and source records attributed to Pichurin, J..

2 recordsLinked to original sources

Curvature-Encoded Photochemistry for Programmable Isolation and Fractionation of Extracellular and Plasma Membrane Vesicles

AbstractLipid-based nanoparticles, including extracellular vesicles (EVs), cell membrane vesicles (CMVs), and biomimetic nanovesicles, are emerging as powerful carriers for therapy and diagnosis due to their ability to transport diverse payloads across biological barriers. EVs, in particular, show promise for liquid biopsy and systemic therapy because of their endogenous origin, biocompatibility, and intrinsic targeting capacity. Cell-derived plasma membrane nanovesicles complement EVs by preserving the source cells membrane architecture and receptor landscape, creating customizable scaffolds for biomimetic drug delivery. However, the full potential of these lipid nanovesicles has been challenging because current isolation workflows are labor-intensive, low-yield, and often lack purity, forming a critical bottleneck for clinical translation and standardized manufacturing. To overcome these challenges, we developed a programmable electrostatic and light-activated platform for isolating lipid vesicles directly from complex biological fluids in a rapid, high-purity, and scalable manner. Our approach employs photocleavable lipid nanoprobes (PLNs) that insert into vesicle membranes in a size-dependent fashion and, together with a cationic polymer, enable efficient capture on a solid support. A brief light exposure cleaves the probes to trigger on-demand release and fractionation of intact vesicles with high speed and precision. Using this platform, we demonstrate high-purity EV isolation with preserved membrane protein functionality, as well as single-step enrichment of right-side-out (RSO) cell membrane nanovesicles that maintain native membrane orientation for effective drug delivery. The capability to rapidly isolate and tailor vesicle subpopulations by size and orientation establishes a unified materials platform for precision nanomedicine and advanced therapeutics, paving the way toward clinical-grade vesicle production and next-generation liquid biopsy applications.

bioengineering↗

Chk2 sustains PLK1 activity in mitosis to ensure proper chromosome segregation

Polo-like kinase 1 (PLK1) protects against genome instability by ensuring timely and accurate mitotic cell division. PLK1 activity is tightly regulated throughout the cell cycle. Although the pathways that initially activate PLK1 in G2 are well-characterized, the factors that directly regulate PLK1 in mitosis remain poorly understood. Here, we identify that human PLK1 activity is sustained by the DNA damage response kinase Checkpoint kinase 2 (Chk2) in mitosis. Chk2 directly phosphorylates PLK1 T210, a residue on its T-loop whose phosphorylation is essential for full PLK1 kinase activity. Loss of Chk2-dependent PLK1 activity causes increased mitotic errors, including chromosome misalignment, chromosome missegregation, and cytokinetic defects. Moreover, Chk2 deficiency increases sensitivity to PLK1 inhibitors, suggesting that Chk2 status may be an informative biomarker for PLK1 inhibitor efficacy. This work demonstrates that Chk2 sustains mitotic PLK1 activity and protects genome stability through discrete functions in interphase DNA damage repair and mitotic chromosome segregation.

cell biology↗