Profile of exosomes related proteins released by differentiated and undifferentiated human keratinocytes

Authors

  • Claudia Chavez-Muñoz,

    1. Department of Surgery, BC Professional Burn and Wound Healing Research Lab., University of British Columbia, Vancouver, British Columbia, Canada
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  • Ruhangiz T. Kilani,

    1. Department of Surgery, BC Professional Burn and Wound Healing Research Lab., University of British Columbia, Vancouver, British Columbia, Canada
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  • Aziz Ghahary

    Corresponding author
    1. Department of Surgery, BC Professional Burn and Wound Healing Research Lab., University of British Columbia, Vancouver, British Columbia, Canada
    • 351-2660 Oak St., Jack Bell Research Centre, Vancouver, BC, Canada V6H 3Z6.
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  • The authors state no conflict of interest

Abstract

Our group has previously demonstrated the capacity of human keratinocytes to release 14-3-3σ into conditioned medium through the mechanism of exosome externalization. In this study the release of other proteins through the same mechanism and the differences in the profiles of 14-3-3 proteins between differentiated (diff-K) and undifferentiated keratinocytes (undiff-K) were investigated. The stimulatory effect of other 14-3-3 isoforms on the expression of MMP-1 in dermal fibroblasts was also evaluated. Exosomes isolated from undiff-K (low Ca2+) and diff-K (high Ca2+) were subjected to proteomic and Western blot analysis. The results showed that more than 50 different cytoplasmic proteins including all seven 14-3-3 protein isoforms (β, σ, η, ε, τ, ζ, and γ) were released from diff-K through the mechanism of exosome externalization. However, in exosomes of undiff-K only four of the 14-3-3 protein isoforms (β, η, ζ, and γ) were detected. Ca2+ treatment increased the release of exosomes from undiff-K by at least two times relative to the control. Consistent with this finding, the stimulatory effect of exosomes containing 14-3-3σ from diff-K had higher MMP-1 stimulatory effect in fibroblasts relative to those exosomes isolated from undiff-K. MMP-1 stimulatory effect of recombinant 14-3-3β and η, tested in this study, in dermal fibroblasts, suggests additional anti-fibrogenic factors other than 14-3-3σ. In conclusion, keratinocytes release many proteins through the mechanism of exosome externalization from which some such as 14-3-3 isoforms may function as extracellular matrix (ECM) modulating factors for dermal fibroblasts. These findings revealed the presence of a novel mechanism by which keratinocytes can potentially interact with fibroblasts. J. Cell. Physiol. 221: 221–231, 2009. © 2009 Wiley-Liss, Inc

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