Keratinocytes in culture accumulate phagocytosed melanosomes in the perinuclear area

  title={Keratinocytes in culture accumulate phagocytosed melanosomes in the perinuclear area},
  author={Hideya Ando and Yoko Niki and Masaki Yoshida and Masaaki Ito and Kaoru Akiyama and Jin-Hwa Kim and Tae‐Jin Yoon and Jeung-Hoon Lee and Mary S. Matsui and Masamitsu Ichihashi},
  journal={Pigment Cell \& Melanoma Research},
There are many techniques for evaluating melanosome transfer to keratinocytes but the spectrophotometric quantification of melanosomes incorporated by keratinocyte phagocytosis has not been previously reported. Here we describe a new method that allows the spectrophotometric visualization of melanosome uptake by normal human keratinocytes in culture. Fontana‐Masson staining of keratinocytes incubated with isolated melanosomes showed the accumulation of incorporated melanosomes in the… 

Melanin Uptake Reduces Cell Proliferation of Human Epidermal Keratinocytes

Together, the direct incubation of keratinocyte with melanin might serve as a useful model to study the potential mechanisms involved in melanin uptake and pigmentation process.

Involvement of pigment globules containing multiple melanosomes in the transfer of melanosomes from melanocytes to keratinocytes

A novel mechanism of melanosome transfer is suggested, wherein melanosomes are packed in membrane globules that bud off from melanocyte dendrites, where they are released into the extracellular space and then phagocytosed by keratinocytes.

Melanosomes are transferred from melanocytes to keratinocytes through the processes of packaging, release, uptake, and dispersion.

A melanosome transfer pathway wherein melanosomes are transferred from melanocytes to keratinocytes via the shedding vesicle system is suggested, which generates pigment globules containing multiple melanosites in a unique manner.

Melanosome uptake is associated with the proliferation and differentiation of keratinocytes

Melanosome uptake is influenced by keratinocyte differentiation status, being highest in mid-stage differentiating keratinocytes in a PAR-2 dependent manner, and inhibited significantly byPAR-2 inhibitor.

Melanosome Distribution in Keratinocytes in Different Skin Types: Melanosome Clusters Are Not Degradative Organelles.

Melanosomal Dynamics Assessed with a Live-Cell Fluorescent Melanosomal Marker

A novel fluorescent melanosomal marker is reported, which was used to measure real-time melanosome dynamics in live human epidermal melanocytes (HEMs) and transfer in melanocyte-keratinocyte co-cultures and revealed a bimodal kinetic profile, with melanosomes exhibiting combinations of slow and fast movement.

Autophagy has a significant role in determining skin color by regulating melanosome degradation in keratinocytes.

The data reveal that autophagy has a pivotal role in skin color determination by regulating melanosome degradation in keratinocytes, and thereby contributes to the ethnic diversity of skin color.

Expression and signaling of the tyrosine kinase FGFR2b/KGFR regulates phagocytosis and melanosome uptake in human keratinocytes

KGFR ligands triggered phagocytosis and melanosome transfer in differentiated keratinocytes, and receptor kinase activity and signaling were required for these effects, suggesting that FGFR2b/KG FR expression/activity and PLCγ signaling pathway play crucial roles in phagocytetosis.

Heparin inhibits melanosome uptake and inflammatory response coupled with phagocytosis through blocking PI3k/Akt and MEK/ERK signaling pathways in human epidermal keratinocytes

The observations suggest that heparin may play an antiphagocytic and anti‐inflammation role in epidermis of human skin.



Keratinocyte-melanocyte interactions during melanosome transfer.

The epidermal-melanin unit is composed of one melanocyte and approximately 36 neighboring keratinocytes, working in synchrony to produce and distribute melanin, and studies of the keratinocyte receptor protease-activated receptor-2 support the phagocytosis theory.

Filopodia are conduits for melanosome transfer to keratinocytes.

A unique role for filopodia in organelle transport is suggested and the presence of SNARE proteins and rab3a on melanosomes is suggested to suggest a novel model system for melanosome transfer to keratinocytes.

Inhibition of melanosome transfer from melanocytes to keratinocytes by lectins and neoglycoproteins in an in vitro model system.

It is proposed that some of the critical molecules involved in the transfer of melanosomes from melanocytes to keratinocytes include plasma membrane lectins and their glycoconjugates and glycoproteins, and that addition of these selected molecules to co-cultures inhibited transfer of fluorochrome.

Melanosome transfer to and translocation in the keratinocyte

Ultraviolet irradiation (UVR) can modulate the process of melanosome transfer from the melanocytes to the keratinocytes and UVR can upregulate expression of PAR‐2 and lectin‐binding receptors and increase phagocytic activity of cultured keratinocyte.

The Quest for the Mechanism of Melanin Transfer

A central role has been established for the protease‐activated receptor‐2 of the keratinocyte which effectuates melanin transfer via phagocytosis, and clues as to what mechanism and molecular machinery will arise with the identification of the function of specific genes which are mutated in diseases that affect transfer are being identified.

Melanosome transfer promoted by keratinocyte growth factor in light and dark skin-derived keratinocytes.

3D image reconstruction by fluorescence microscopy and ultrastructural analysis through transmission electron microscopy showed differences in the distribution pattern of the beads in light and dark keratinocytes, consistent with the different melanosome distribution in human skin.

Role of cytoplasmic dynein in perinuclear aggregation of phagocytosed melanosomes and supranuclear melanin cap formation in human keratinocytes.

Findings indicate that in human keratinocytes, the retrograde microtubule motor cytoplasmic dynein mediates the perinuclear aggregation of phagocytosed melanosomes, participates in the formation of the supranuclear melanin cap or "microparasol" and serves as a mechanism to help protect the nucleus from ultraviolet-induced DNA damage.

The protease-activated receptor 2 regulates pigmentation via keratinocyte-melanocyte interactions.

Evidence is provided that the protease-activated receptor 2 (PAR-2) expressed on keratinocytes, but not on melanocytes, is involved in melanosome transfer and therefore may regulate pigmentation.

Influence of α‐melanocyte‐stimulating hormone and of ultraviolet radiation on the transfer of melanosomes to keratinocytes

  • V. ViradorJ. Muller V. Hearing
  • Biology
    FASEB journal : official publication of the Federation of American Societies for Experimental Biology
  • 2002
A combination of signals that increase melanosome production and release by melanocytes and that stimulate phagocytosis by keratinocytes are the most relevant mechanisms involved in skin tanning.

Keratinocytes play a role in regulating distribution patterns of recipient melanosomes in vitro.

The results suggest that regulatory factor(s) within the keratinocyte determine recipient melanosome distribution patterns, and that recipients melanosomes, regardless of origin, are predominantly distributed individually by keratinocytes from dark skin, and in membrane-bound clusters by those from light skin.