Related Experiment Videos
Filopodia are conduits for melanosome transfer to keratinocytes
Glynis Scott1, Sonya Leopardi, Stacey Printup
1Department of Dermatology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA. Glynis_Scott@urmc.rochester.edu
Abstract:
Melanosomes are specialized melanin-synthesizing organelles critical for photoprotection in the skin. Melanosome transfer to keratinocytes, which involves whole organelle donation to another cell, is a unique biological process and is poorly understood. Time-lapse digital movies and electron microscopy show that filopodia from melanocyte dendrites serve as conduits for melanosome transfer to keratinocytes. Cdc42, a small GTP-binding protein, is known to mediate filopodia formation. Melanosome-enriched fractions isolated from human melanocytes expressed the Cdc42 effector proteins PAK1 and N-WASP by western blotting. Expression of constitutively active Cdc42 (Cdc42(V12)) in melanocytes co-cultured with keratinocytes induced a highly dendritic phenotype with extensive contacts between melanocytes and keratinocytes through filopodia, many of which contained melanosomes. These results suggest a unique role for filopodia in organelle transport and, in combination with our previous work showing the presence of SNARE proteins and rab3a on melanosomes, suggest a novel model system for melanosome transfer to keratinocytes.
Insights
Melanosome transfer to skin cells occurs via filopodia, specialized cell extensions. This process involves Cdc42 protein, crucial for filopodia formation and organelle transport.
Area of Science:
- Cell Biology
- Dermatology
- Biochemistry
Background:
- Melanosomes are vital organelles for skin photoprotection.
- Melanosome transfer to keratinocytes is a unique but poorly understood cellular process.
Purpose of the Study:
- To elucidate the mechanism of melanosome transfer from melanocytes to keratinocytes.
- To investigate the role of filopodia and Cdc42 in melanosome transport.
Main Methods:
- Utilized time-lapse digital movies and electron microscopy.
- Performed western blotting on melanosome-enriched fractions.
- Co-cultured melanocytes with constitutively active Cdc42 (Cdc42(V12)) and keratinocytes.
Main Results:
- Filopodia from melanocyte dendrites act as conduits for melanosome transfer.
- Melanosome fractions express Cdc42 effector proteins PAK1 and N-WASP.
- Cdc42(V12) expression induced extensive filopodial contacts containing melanosomes between cells.
Conclusions:
- Filopodia play a unique role in organelle transport.
- A novel model for melanosome transfer involving filopodia and Cdc42 is proposed.