Analogs of LDL Receptor Ligand Motifs in Dengue Envelope and Capsid Proteins as Potential Codes for Cell Entry

Figure 6

HeLa cell entry and nuclear translocation of Dsp3CP-FITC. Image in frame (A1) shows cell uptake and nuclear translocation of Dsp3CP-FITC alone. Image (A2), an enlarged region of (A1), shows fluorescence suggestive of endosome-like structures and clusters in and about the nuclear space. Image (B2) shows location of Dsp3CP-FITC signal in the presence of Apo E-2 peptide. Image (B2), an enlarged region of (B1), also shows evidence that Dsp3CP-FITC signal occurs in endosomes and the nuclear space apparently unaffected by the addition of unlabeled Apo E-2 at 1.5 molar excess. Images in rows (C) and (D) were obtained in dual label experiments using 24 μL of Dsp3CP-FITC (50 μg) and Apo E-CM-DiI (75 μg) mix. Apo E-CM-DiI-and Dsp3CP-FITC were added to live HeLa cells in FBS-depleted EMEM then incubated at ambient temperature for 15 and 90 minutes, (C) and (D) series, respectively. Areas 1, 2, and 3 in image (C) are enlarged to show typical colocalized signals on the cell membrane. Green signal also clearly appears in the nucleus at this early time point. In (D), signals appear separate as well as colocalized within the cell perimeter. Interestingly, FITC signal appears to be dispersed both within the cell and in the extracellular space while Apo E CM-DiI signal is indicated mostly within the cells. Cell nuclei appear to contain both green and red label.