Platelet-activating factor induces proliferation in differentiated keratinocytes
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Increased levels of platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) are found in several inflammatory dermatoses, but PAF’s exact role in epidermis is uncertain. In order to better understand the physiological consequences of excess PAF production in epidermis, we examined the gene regulatory effects of PAF short-term stimulation in differentiated HaCaT keratinocytes by transcriptional profiling. Even though PAF induces COX2 expression, we found that PAF regulates only few genes associated with inflammation in differentiated keratinocytes. Rather, we show that natural PAF rapidly regulates genes involved in proliferation, (anti)-apoptosis and migration, all sub-processes of re-epithelialization and wound healing. Moreover, profiling of phosphorylated kinases, cellular wound-scratch experiments, resazurin assay and flow cytometry cell cycle phase analysis all support a role for PAF in keratinocyte proliferation and epidermal re-epithelialization. In conclusion, these results suggest that PAF acts as an activator of proliferation and may, therefore, function as a connector between inflammation and proliferation in differentiated keratinocytes.
KeywordsHaCaT Transcriptional profiling Inflammation Wound healing Psoriasis
Epidermal growth factor
Mitogen-activated protein kinase
Minimum information about microarray experiment
Platelet-activating factor receptor
The study was supported financially by the Norwegian Research Council Grant to AJF and the NTNU Medical Technology Program Grant to KMJ. We thank Mari Sæther, Thuy Nguyen, Sjur Huseby, Hans-Richard Brattbakk, Endre Anderssen and Vidar Beisvåg for excellent technical assistance.
Conflict of interest
The authors state no conflict of interest.
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