Melanophores: A model system for neuronal transport and exocytosis?

Abstract

Black pigment cells, melanophores, from lower vertebrates are specialized in bidirectional and coordinated translocation of pigment granules, melanosomes, in the cytoplasm. Melanophores develop from the neuronal crest and are most abundant in the dermal and epidermal layers of the skin, where the intracellular distribution of the pigment significantly influences the color of the animal. The transport of pigment is dependent on an intact cytoskeleton and motor proteins associated with cytoskeletal components. The easily cultured melanophores have proved to be excellent models for organelle transport because the intracellular movements of pigment can be visualized via light microscopy, and the granules move in response to defined chemical signals. The ease of achieving a combination of morphological and functional transport studies is the advantage of the melanophore system, and studies on pigment cells have revealed new components of the transport machinery, including molecular motors, their adapters, and transfer of vesicles to other cells. Many cellular components are transported with a combination of the actin- and microtubule-based transport systems, and, since all eukaryotic organisms rely on functional intracellular transport and an intact cytoskeleton, studies on melanophores are important for many aspects of cell biology, including axonal transport. In this review, we present an overview of the research on the pigment transport system and the potential use of pigment cells as a model system.

Intracellular transport driven by cytoskeletal motors: General mechanisms and defects

“…The stationary density profile can be derived from (22)(23)(24). It is found to be in agreement with the exact expression valid in the large system size limit [334], with in particular the same localization length ξ.…”

“…We shall see that a specific family of molecular motors uses the actin filaments as tracks (see section 3.1.5), and though we shall not develop the role played by actin lattices in intracellular transport, it should be kept in mind that, as a complement to MT based transport, part of the transport is performed along the actin networks [23] that, for example, cover the inner side of the cell membranes. This is in particular true for transport along the axon (section 7.1).…”

VDR Potentiation and NMDA R Inhibition Facilitates Axo-Dendritic Process Formation in Melanocyte Model for Pigmented Cells in Parkinsonism

“…This study however shows that inhibition of the NMDA R did facilitate the formation of long axon-like processes extending between two adjacent melanocytes, while the VDR stimulation caused short process formation radiating from the cell body and representing an array of bi-directional vesicular transport system. Similar to our proposition in this study, Aspengren et al [40] suggested that Melanocytes develop from the neuronal crest and are most abundant in the dermal and epidermal layers of the skin, where the intracellular distribution of the pigment significantly influences the color of the animal. The transport of pigment is dependent on an intact cytoskeleton and motor proteins associated with cytoskeletal components.…”

Panax ginseng induces anterograde transport of pigment organelles in Xenopus melanophores

“…The inhibition or activation of AC is followed by decreased or increased levels of cAMP and an inhibited or activated PKA, which alters the phosphorylations of unknown target proteins, finally leading to retrograde (aggregation) or anterograde (dispersion) movement. The fast change in colour makes the melanophores a perfect system for studying the effect of different substances on G-protein-coupled signalling and their effects on intracellular transport (Aspengren et al, 2007). Here we use the melanophores to show that Panax ginseng affects organelle transport by inducing anterograde movement of the melanosomes.…”