ABSTRACT
Background:
Exosomes have been demonstrated to carry
proteins, membrane lipids, mRNAs and
microRNAs which can be transferred to surrounding
cells and regulate the functions of those recipient
cells.
Objectives:
The objective of the study was to investigate the effects of
exosomes released by
keratinocytes and
fibroblasts on the proliferation,
tyrosinase activity and
melanogenesis of
melanocytes.
Methods:
Melanocytes,
keratinocytes and
fibroblasts obtained from
human foreskin were cultured and
exosomes secreted by
keratinocytes and
fibroblasts were harvested from the
culture supernatants by
ultracentrifugation. Each exosome fraction was divided into two parts; one part was subjected to
high-throughput sequencing using an Illumina HiSeq sequencer to characterize the
microRNA expression profiles, while the other part was labeled with the
fluorescent dye PKH67 and was then co-cultivated with epidermal
melanocytes.
Results:
High-throughput sequencing analysis showed 168 differentially expressed
microRNA within
exosomes derived from
keratinocytes and from
fibroblasts, 97 of those being up-regulated with the other 71 down-regulated.
Gene ontology analysis showed that the target
genes responsible for these differentially expressed
microRNAs were mainly enriched in the
protein-binding region of molecular functions. Kyoto
Encyclopedia of
Genes and
Genomes (KEGG) pathway
analysis showed that target
genes regulated by differentially expressed
microRNA were mainly involved in
mitogen-activated protein kinase (MAPK) signaling pathway,
Ras signaling pathway, cAMP signaling pathway and
Wnt signaling pathway.
Keratinocyte-derived
exosomes were taken up by
melanocytes co-cultured with them and promoted the proliferation,
tyrosinase activity and
melanin synthesis of those
melanocytes. However,
fibroblast-derived
exosomes had no
similar effects on
melanocytes.
Conclusion:
Keratinocyte-derived
exosomes but not
fibroblast-derived
exosomes were taken up by
melanocytes in
co-culture and significantly stimulated their proliferation,
tyrosinase activity and
melanin synthesis. Those different effects may be mainly due to the differential expression of
microRNAs in
exosomes derived from the different types of
cells.
Limitations:
Electron microscopy of the obtained
exosomes and in-depth study of apparently differentially expressed
microRNAs were not performed