Abstract
Paclitaxel (PTX), a chemotherapeutic drug, affects microtubule dynamics and influences endocytic trafficking. However, the mechanism and the dynamics of altered endocytic trafficking by paclitaxel treatment in single living cells still remain elusive. By labeling quantum dots (QDs) to the epidermal growth factor (EGF), we continuously tracked the endocytosis and post-endocytic trafficking of EGF receptors (EGFRs) in A549 cells for a long time interval. A single-cell analysis method was introduced to quantitatively study the dynamics of endocytic trafficking. Compared with the control cells, the velocity of directed motion was reduced by 30% due to the suppression of high speed movements of EGF-QDs along the microtubules in PTX-treated cells. The endocytic trafficking in PTX-treated cells was mainly via super-diffusive mode of motion, whereas in control cells, it was mostly via sub-diffusive mode of motion. Moreover, PTX shortened endosomal trafficking and prevented EGF-QDs from moving to the perinuclear area via the rapid delivery of EGF-QDs into the peripheral lysosomes. The present study may shed light on the mechanism of the effect of PTX on the treatment of lung cancer.
Highlights
Endocytosis and post-endocytic trafficking of surface-expressed receptor proteins are complex dynamic processes for eukaryotic cells
We first studied the dynamics of EGF receptors (EGFRs) endocytosis during the first 5 min by analyzing the temporal evolution of the fluorescent intensity of epidermal growth factor (EGF)-Quantum dots (QDs)
The EGFRs on the cell surface were labeled with EGF and QDs using the consecutive binding method previously described [16,36,37,38]
Summary
Endocytosis and post-endocytic trafficking of surface-expressed receptor proteins are complex dynamic processes for eukaryotic cells. These processes are critical throughout the whole cellular signaling, including receptor internalization, endosomal trafficking, and lysosomal degradation or recycling to the plasma membrane [1,2,3,4]. Some details about the internalization mechanism and dynamic information of growth factor receptors have been revealed, including receptor heterodimerization, endosomal transport rate, and retrograde transport. These previous studies facilitated the measurement of endosomal trafficking and provided closer insights into the endocytic pathway. The capability of studying single cells will bring better understanding of cellular heterogeneity
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