title: Depicting Binding-Mediated Translocation of HIV-1 Tat Peptides in Living Cells with Nanoscale Pens of Tat-Conjugated Quantum Dots.
abstract: Cell-penetrating peptides (CPPs) can translocate across cell membranes, and thus have great potential for the cellular delivery of macromolecular cargoes. However, the mechanism of this cellular uptake process is not yet fully understood. In this study, a time-lapse single-particle light-sheet microscopy technique was implemented to obtain a parallel visualization of the translocating process of individual human immunodeficiency virus 1 (HIV-1) transactivator of transcription (Tat) peptide conjugated quantum dots (TatP-QDs) in complex cellular terrains. Here, TatP-QDs served as nanoscale dynamic pens, which depict remarkable trajectory aggregates of TatP-QDs on the cell surface. Spectral-embedding analysis of the trajectory aggregates revealed a manifold formed by isotropic diffusion and a fraction of directed movement, possibly caused by interaction between the Tat peptides and heparan sulfate groups on the plasma membrane. Further analysis indicated that the membrane deformation induced by Tat-peptide attachment increased with the disruption of the actin framework in cytochalasin D (cyto D)-treated cells, yielding higher interactions on the TatP-QDs. In native cells, the Tat peptides can remodel the actin framework to reduce their interaction with the local membrane environment. Characteristic hot spots for interaction were detected on the membrane, suggesting that a funnel passage may have formed for the Tat-coated particles. This finding offers valuable insight into the cellular delivery of nanoscale cargo, suggesting an avenue for direct therapeutic delivery.
authors.affiliation: The T.K.P. Research Center for Photonics, Chiao Tung University, Hsinchu 300, Taiwan. raw476@gmail.com.
authors.forename: Chien Y
authors.initials: CY
authors.lastname: Lin
authors.affiliation: The T.K.P. Research Center for Photonics, Chiao Tung University, Hsinchu 300, Taiwan. jyhuang@faculty.nctu.edu.tw.
authors.forename: Jung Y
authors.initials: JY
authors.lastname: Huang
authors.affiliation: Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan 350, Taiwan. lwlo@nhri.org.tw.
authors.forename: Leu-Wei
authors.initials: LW
authors.lastname: Lo
mesh_terms: D002452:Cell Count; D002470:Cell Survival; D015696:Gene Products, tat; D015497:HIV-1; D049329:Nanostructures; D010455:Peptides; D045663:Quantum Dots; D014178:Translocation, Genetic
chemical_list: D015696:Gene Products, tat; D010455:Peptides
keywords: actin filaments; cell-penetrating  peptides; heparan sulfate proteoglycan; live cell; plasma membrane; single-particle  tracking