Figure 6.

Microtubules are required for the entry and/or maintenance of late endosomes in NEI. A, FEMX-I cells expressing Rab7–RFP were double-immunolabeled for α-tubulin and SUN2 prior to CLSM. B, FEMX-I cells were treated without (Control) or with nocodazole (Noc., 1 μm) for 45 min prior to double-immunolabeling for α-tubulin or VAP-A (top and bottom panels, respectively) and Rab7. DMSO-treated cells were used as solvent control. A single x-y optical section is presented. Area of NEI is magnified. Arrows indicate the presence of a given protein in NEI. C, number of cells containing VAP-A⁺ NEI-associated Rab7⁺ late endosomes under specific conditions was quantified. The means ± S.D. are shown (n = 3). More than 30 cells were evaluated per experiment, and their average is indicated. p value is indicated. D, drawing showing molecular interactions involved in the association of Rab7⁺ late endosomes (LE) with NEI. Player(s) involved in the interaction of late endosomes with microtubules remains to be identified (?). PH, pleckstrin homology domain of ORP3; INM, ONM, inner and outer nuclear membrane, respectively; nu, nucleoplasm. Scale bars, 5 μm.