Retinal-loukoumasomes reside in the perinuclear space in close association with lamin in retinoblastoma cells.

<p>A-C. The perimeter of retinal-loukoumasomes are outlined by intense lamin B1 staining suggesting that they are perinuclear. A. Y79 cells immunostained for beta-III tubulin using the SDL.3D10 antibody (green), lamin B1 (red) and costained for DAPI (blue). The z positions of single slices from the z-stack data are indicated. White arrows highlight retinal-loukoumasomes, while yellow arrows highlight intense lamin B1 staining. B. Tubulin, lamin B1 and DAPI intensity profiles on this same cell was performed. Fluorescence intensities indicate that tubulin nestles within a lamin fold near an area of the nucleus lacking DNA labelling. C. Confocal orthogonal views of the same Y79 cell at a given z position (z = 6.4 μm) are shown. Each successive orthogonal step (labelled 1–4) is 1.6 μm apart (arrows indicate the direction in which steps were taken). An intimate association with lamin B1 folds and the loukoumasome is evident. Polymerized tubulin “tubulin tail” appears to be continuous with the toroidal loukoumasome. D. A large loukoumasome is shown in a Weri-Rb 27 cell immunolabeled for beta-III tubulin together with lamin B1 and stained with DAPI. As seen for the loukoumasome in A-C, a beta-III tubulin “tail” is also evident here. E. The lamin foldings around loukoumasomes were also evident in Y79 cells coimmunolabeled for alpha-tubulin with lamin B1 and counterstained with DAPI. F. Representative images showing the interaction between beta-III tubulin and lamin B1 as revealed by the in situ PLA. Punctate red fluorescence indicates beta-III tubulin and lamin are in close proximity.