Translocation and clustering of endosomes and lysosomes depends on microtubules.

Abstract

Indirect immunofluorescence labeling of normal rat kidney (NRK) cells with antibodies recognizing a lysosomal glycoprotein (LGP 120; Lewis, V., S.A. Green, M. Marsh, P. Vihko, A. Helenius, and I. Mellman, 1985, J. Cell Biol., 100:1839-1847) reveals that lysosomes accumulate in the region around the microtubule-organizing center (MTOC). This clustering of lysosomes depends on microtubules. When the interphase microtubules are depolymerized by treatment of the cells with nocodazole or during mitosis, the lysosomes disperse throughout the cytoplasm. Lysosomes recluster rapidly (within 30-60 min) in the region of the centrosomes either upon removal of the drug, or, in telophase, when repolymerization of interphase microtubules has occurred. During this translocation process the lysosomes can be found aligned along centrosomal microtubules. Endosomes and lysosomes can be visualized by incubating living cells with acridine orange. We have analyzed the movement of these labeled endocytic organelles in vivo by video-enhanced fluorescence microscopy. Translocation of endosomes and lysosomes occurs along linear tracks (up to 10 microns long) by discontinuous saltations (with velocities of up to 2.5 microns/s). Organelles move bidirectionally with respect to the MTOC. This movement ceases when microtubules are depolymerized by treatment of the cells with nocodazole. After nocodazole washout and microtubule repolymerization, the translocation and reclustering of fluorescent organelles predominantly occurs in a unidirectional manner towards the area of the MTOC. Organelle movement remains unaffected when cells are treated with cytochalasin D, or when the collapse of intermediate filaments is induced by microinjected monoclonal antivimentin antibodies. It can be concluded that translocation of endosomes and lysosomes occurs along microtubules and is independent of the intermediate filament and microfilament networks.

The unconventional myosin-VIIa associates with lysosomes

“…In cultured cell lines such as ARPE-19 or COS-7, which produce very few or no melanosomes, myosin-VIIa associates predominantly with lysosomes; in retina tissue, however, myosin-VIIa is more evident on melanosomes. Lysosome organization is maintained by the microtubule network with its motors, as has been shown for other cell types (Matteoni and Kreis 1987). Gibbs et al (2004) suggested that myosin-VIIa may play a role in short range movements and temporary tethering of melanosomes.…”

“…5). Previous studies have shown that long range lysosomal motility occurs along the microtubule cytoskeleton (Matteoni and Kreis 1987). Treatment of ARPE-19 cells with 33μM nocodazole for 2h led to depolymerization of microtubules.…”

Biogenesis of Salmonella typhimurium-containing vacuoles in epithelial cells involves interactions with the early endocytic pathway

“…However, either of these methods could interfere with the early traf®cking events involved in SCV biogenesis. It is particularly well documented that microtubules, which are essential for transport from early to late endosomes, are disrupted by incubation at low temperatures (Matteoni and Kreis, 1989;Gruenberg et al, 1989;D'Arrigo et al, 1997). As the expression of invasion loci in Salmonella, and consequently the invasion process itself, is known to be affected by physiological conditions (Ernst et al, 1990;Lee and Falkow, 1990;Behlau and Miller, 1993;Kusters et al, 1993;Schiemann, 1995), we examined whether ef®cient invasion could be obtained in 5 min by measuring bacterial invasion at various points on the growth curve.…”

Intracellular trafficking of nonviral vectors

“…These drugs likely prevented trafficking to lysosomes, as endosomes require intact microtubules to translocate from the plasma membrane to lysosomes. [181][182][183][184] The authors speculated that microtubule depolymerization also activated the NF-kB transcription factor, thus inducing NF-kB-dependent gene expression, as described elsewhere. 185 Molecular conjugates.…”