Bidirectional pigment granule migration in isolated retinal pigment epithelial cells requires actin but not microtubules

King-Smith, Christina; Paz, Pedro; Lee, Cary W.; Lam, Winnie; Burnside, Beth

doi:10.1002/(sici)1097-0169(1997)38:3<229::aid-cm2>3.0.co;2-0

Cited by 29 publications

(64 citation statements)

References 49 publications

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“…This notion is confirmed by studies on melanophores, where bidirectional long-range pigment motility depends on a Kinesin-2 and dynein, whereas F-actin and Myosin-V are involved in short-range dispersal, apical tethering, and fine tuning of MT-based motility (reviewed in Brown, 1999). However, there are exceptions to this rule, because long-distance pigment granule traffic in retinal pigment epithelial cells is F-actin dependent (King-Smith et al, 1997). However, there are exceptions to this rule, because long-distance pigment granule traffic in retinal pigment epithelial cells is F-actin dependent (King-Smith et al, 1997).…”

Section: Introductionmentioning

confidence: 80%

Myosin-V, Kinesin-1, and Kinesin-3 Cooperate in Hyphal Growth of the FungusUstilago maydis

Schuchardt

Daniela

Thines

et al. 2005

MBoC

107

147

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Long-distance transport is crucial for polar-growing cells, such as neurons and fungal hyphae. Kinesins and myosins participate in this process, but their functional interplay is poorly understood. Here, we investigate the role of kinesin motors in hyphal growth of the plant pathogen Ustilago maydis. Although the microtubule plus-ends are directed to the hyphal tip, of all 10 kinesins analyzed, only conventional kinesin (Kinesin-1) and Unc104/Kif1A-like kinesin (Kinesin-3) were up-regulated in hyphae and they are essential for extended hyphal growth. deltakin1 and deltakin3 mutant hyphae grew irregular and remained short, but they were still able to grow polarized. No additional phenotype was detected in deltakin1rkin3 double mutants, but polarity was lost in deltamyo5rkin1 and deltamyo5rkin3 mutant cells, suggesting that kinesins and class V myosin cooperate in hyphal growth. Consistent with such a role in secretion, fusion proteins of green fluorescent protein and Kinesin-1, Myosin-V, and Kinesin-3 accumulate in the apex of hyphae, a region where secretory vesicles cluster to form the fungal Spitzenkörper. Quantitative assays revealed a role of Kin3 in secretion of acid phosphatase, whereas Kin1 was not involved. Our data demonstrate that just two kinesins and at least one myosin support hyphal growth.

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Section: Introductionmentioning

confidence: 80%

Myosin-V, Kinesin-1, and Kinesin-3 Cooperate in Hyphal Growth of the FungusUstilago maydis

Schuchardt

Daniela

Thines

et al. 2005

MBoC

107

147

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“…In addition to the initial association of the melanosome with the apical actin cytoskeleton and/or movement through it, Rab27a/myosin VIIa may play a role in the subsequent movement within the apical processes. Melanosome movement along apical processes has been most extensively studied in teleost RPE, where both dispersion to the tips and aggregation within the cell body are dependent on actin filaments because they are disrupted upon cytochalasin treatment (King-Smith et al, 1997). Aggregation but not dispersion may also have a requirement for microtubules (Troutt and Burnside, 1989).…”

Section: How Does Rab27a Regulate Melanosome Movement Within the Rpe?mentioning

confidence: 99%

The Role of Rab27a in the Regulation of Melanosome Distribution within Retinal Pigment Epithelial Cells

Futter

Ramalho

Jaissle

et al. 2004

MBoC

108

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Melanosomes within the retinal pigment epithelium (RPE) of mammals have long been thought to exhibit no movement in response to light, unlike fish and amphibian RPE. Here we show that the distribution of melanosomes within the mouse RPE undergoes modest but significant changes with the light cycle. Two hours after light onset, there is a threefold increase in the number of melanosomes in the apical processes that surround adjacent photoreceptors. In skin melanocytes, melanosomes are motile and evenly distributed throughout the cell periphery. This distribution is due to the interaction with the cortical actin cytoskeleton mediated by a tripartite complex of Rab27a, melanophilin, and myosin Va. In ashen (Rab27a null) mice RPE, melanosomes are unable to move beyond the adherens junction axis and do not enter apical processes, suggesting that Rab27a regulates melanosome distribution in the RPE. Unlike skin melanocytes, the effects of Rab27a are mediated through myosin VIIa in the RPE, as evidenced by the similar melanosome distribution phenotype observed in shaker-1 mice, defective in myosin VIIa. Rab27a and myosin VIIa are likely to be required for association with and movement through the apical actin cytoskeleton, which is a prerequisite for entry into the apical processes.

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“…In the RPE of fi sh, both microtubules and actin fi laments, the cytoskeletal tracks for organelle motility, are present in apical projections, and both contribute to melanosome motility. Rather, disruption of actin fi laments blocked both pigment granule aggregation and dispersion (King-Smith et al, 1997 ). However, in dissociated RPE cells cultured in vitro , depolymerization of microtubules had no effect on pigment granule movement through apical projections.…”

Section: Introductionmentioning

confidence: 88%

“…RPE cells were isolated as described previously (King-Smith et al, 1997 ;King-Smith, 2009 ). Fish were dark adapted for at least 30 min and anesthetized in 75 mg/L MS-222 (Tricaine, Sigma-Aldrich, St. Louis, MO).…”

Section: Rpe Cell Isolationmentioning

confidence: 99%

“…Microtubule disruption in vivo or in eyecup preparations in situ blocked melanosome movement in both the RPE CB and apical projections Troutt & Burnside, 1989 ). In contrast, actin fi laments within apical projections are both necessary and suffi cient for aggregation and dispersion of melanosomes (King-Smith et al, 1997 ). Rather, disruption of actin fi laments blocked both pigment granule aggregation and dispersion (King-Smith et al, 1997 ).…”

Section: Introductionmentioning

confidence: 99%

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Orientation of actin filaments in teleost retinal pigment epithelial cells, and the effect of the lectin, Concanavalin A, on melanosome motility

et al. 2014

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Retinal pigment epithelial cells of teleosts contain numerous melanosomes (pigment granules) that exhibit light-dependent motility. In light, melanosomes disperse out of the retinal pigment epithelium (RPE) cell body (CB) into long apical projections that interdigitate with rod photoreceptors, thus shielding the photoreceptors from bleaching. In darkness, melanosomes aggregate through the apical projections back into the CB. Previous research has demonstrated that melanosome motility in the RPE CB requires microtubules, but in the RPE apical projections, actin filaments are necessary and sufficient for motility. We used myosin S1 labeling and platinum replica shadowing of dissociated RPE cells to determine actin filament polarity in apical projections. Actin filament bundles within RPE apical projections are uniformly oriented with barbed ends toward the distal tips. Treatment of RPE cells with the tetravalent lectin, Concanavalin A, which has been shown to suppress cortical actin flow by crosslinking of cell-surface proteins, inhibited melanosome aggregation and stimulated ectopic filopodia formation but did not block melanosome dispersion. The polarity orientation of F-actin in apical projections suggests that a barbed-end directed myosin motor could effect dispersion of melanosomes from the CB into apical projections. Inhibition of aggregation, but not dispersion, by ConA confirms that different actin-dependent mechanisms control these two processes and suggests that melanosome aggregation is sensitive to treatments previously shown to disrupt actin cortical flow.

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Bidirectional pigment granule migration in isolated retinal pigment epithelial cells requires actin but not microtubules

Cited by 29 publications

References 49 publications

Myosin-V, Kinesin-1, and Kinesin-3 Cooperate in Hyphal Growth of the FungusUstilago maydis

Myosin-V, Kinesin-1, and Kinesin-3 Cooperate in Hyphal Growth of the FungusUstilago maydis

The Role of Rab27a in the Regulation of Melanosome Distribution within Retinal Pigment Epithelial Cells

Orientation of actin filaments in teleost retinal pigment epithelial cells, and the effect of the lectin, Concanavalin A, on melanosome motility

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