title: Human Keratinocytes Respond to Extracellular UTP by Induction of Hyaluronan Synthase 2 Expression and Increased Hyaluronan Synthesis.
abstract: The release of nucleotides into extracellular space is triggered by insults like wounding and ultraviolet radiation, resulting in stimulatory or inhibitory signals via plasma membrane nucleotide receptors. As similar insults are known to activate hyaluronan synthesis we explored the possibility that extracellular UTP or its breakdown products UDP and UMP act as mediators for hyaluronan synthase (HAS) activation in human epidermal keratinocytes. UTP increased hyaluronan both in the pericellular matrix and in the culture medium of HaCaT cells. 10-100 μm UTP strongly up-regulatedHAS2expression, although the other hyaluronan synthases (HAS1, HAS3) and hyaluronidases (HYAL1,HYAL2) were not affected. TheHAS2response was rapid and transient, with the maximum stimulation at 1.5 h. UDP exerted a similar effect, but higher concentrations were required for the response, and UMP showed no stimulation at all. Specific siRNAs against the UTP receptor P2Y2, and inhibitors of UDP receptors P2Y6and P2Y14, indicated that the response to UTP was mediated mainly through P2Y2and to a lesser extent via UDP receptors. UTP increased the phosphorylation of p38, ERK, CREB, and Ser-727 of STAT3 and induced nuclear translocation of pCaMKII. Inhibitors of PKC, p38, ERK, CaMKII, STAT3, and CREB partially blocked the activation ofHAS2expression, confirming the involvement of these pathways in the UTP-inducedHAS2response. The present data reveal a selective up-regulation ofHAS2expression by extracellular UTP, which is likely to contribute to the previously reported rapid activation of hyaluronan metabolism in response to tissue trauma or ultraviolet radiation.
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Jokela
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Riikka
authors.initials: R
authors.lastname: Kärnä
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: Rauhala
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Bart
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Sanna
authors.initials: S
authors.lastname: Pasonen-Seppänen
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Sanna
authors.initials: S
authors.lastname: Oikari
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland tammi@uef.fi.
authors.forename: Markku I
authors.initials: MI
authors.lastname: Tammi
authors.affiliation: From the Institute of Biomedicine, University of Eastern Finland, 70211 Kuopio, Finland.
authors.forename: Raija H
authors.initials: RH
authors.lastname: Tammi
mesh_terms: D002460:Cell Line; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism*; D015854:Up-Regulation; D014544:Uridine Triphosphate / Q000378:metabolism*
chemical_list: D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C101754:HAS2 protein, human; D000076002:Hyaluronan Synthases; D014544:Uridine Triphosphate
keywords: P2Y; UTP; cell signaling; extracellular nucleotide; hyaluronan; hyaluronan synthesis; keratinocyte; nucleotide; purinergic receptor