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Updated: Jun 15, 2026
3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles
Published on: October 1, 2014
Particle tracking of intracellular trafficking of octaarginine-modified liposomes: a comparative study with
Hidetaka Akita1, Kaoru Enoto, Tomoya Masuda
1Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo City, Japan. akita@pharm.hokudai.ac.jp
Abstract:
It is previously reported that octaarginine (R8)-modified liposome (R8-Lip) was taken up via macropinocytosis, and subsequently delivered to the nuclear periphery. In the present study, we investigated the mechanism for the cytoplasmic transport of R8-Lips, comparing with that for adenovirus. Treatment with microtubule-disruption reagent (nocodazole) inhibited the transfection activity of plasmid DNA (pDNA)-encapsulating R8-Lip more extensively than that of adenovirus. The directional transport of R8-Lips along green fluorescent protein (GFP)-tagged microtubules was observed; however, the velocity was slower than those for adenovirus or endosomes that were devoid of R8-Lips. These directional motions were abrogated in R8-Lips by nocodazole treatment, whereas adenovirus continued to undergo random motion. This finding suggests that the nuclear access of R8-Lip predominantly involves microtubule-dependent transport, whereas an apparent diffusive motion is also operative in nuclear access of adenovirus. Furthermore, quantum dot-labeled pDNA underwent directional motion concomitantly with rhodamine-labeled lipid envelopes, indicating that the R8-Lips were subject to microtubule-dependent transport in the intact form. Dual particle tracking of carriers and endosomes revealed that R8-Lip was directionally transported, associated with endosomes, whereas this occurs after endosomal escape in adenovirus. Collectively, the findings reported herein indicate that vesicular transport is a key factor in the cytoplasmic transport of R8-Lips.
Insights
Octaarginine (R8)-modified liposomes utilize microtubule-dependent transport for cytoplasmic delivery, unlike adenovirus which also uses random motion. This highlights vesicular transport as key for R8-Lip nuclear access.
Area of Science:
- Cell Biology
- Nanotechnology
- Drug Delivery
Background:
- Octaarginine (R8)-modified liposomes (R8-Lips) are known to be internalized via macropinocytosis and reach the nuclear periphery.
- The precise mechanism of cytoplasmic transport for R8-Lips remains incompletely understood.
Purpose of the Study:
- To elucidate the cytoplasmic transport mechanism of R8-Lips.
- To compare the transport pathways of R8-Lips with those of adenovirus.
Main Methods:
- Utilized microtubule disruption with nocodazole to assess transport dependency.
- Performed live-cell imaging to track R8-Lip and adenovirus movement along microtubules.
- Employed quantum dot and rhodamine labeling for intact R8-Lip tracking.
- Conducted dual particle tracking of carriers and endosomes.
Main Results:
- Microtubule disruption significantly inhibited R8-Lip transfection more than adenovirus.
- R8-Lips exhibited directional, albeit slower, movement along microtubules compared to adenovirus.
- Nocodazole treatment abolished R8-Lip directional motion, while adenovirus showed random movement.
- Intact R8-Lips demonstrated microtubule-dependent transport, moving directionally with their lipid envelopes.
- R8-Lips were directionally transported associated with endosomes, unlike adenovirus which undergoes endosomal escape.
Conclusions:
- Cytoplasmic transport of R8-Lips is predominantly mediated by microtubule-dependent vesicular transport.
- Adenovirus utilizes both microtubule-dependent and random motion for nuclear access.
- Understanding R8-Lip transport mechanisms is crucial for optimizing liposomal drug delivery systems.
