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 () 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-regulated expression, although the other hyaluronan synthases () and hyaluronidases (, ) were not affected. The response 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 P2Y, and inhibitors of UDP receptors P2Y and P2Y, indicated that the response to UTP was mediated mainly through P2Y and 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 of expression, confirming the involvement of these pathways in the UTP-induced response. The present data reveal a selective up-regulation of expression 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.

Knockout of hyaluronan synthase 1, but not 3, impairs formation of the retrocalcaneal bursa

“…Unexpectedly, HAS-deficient mice did not display any significant differences in tendon HA contents or HAS expression compared to WT mice, at any age. Since HAS2 appears to be the predominant isoform for synthesis of high molecular weight HA in connective tissues, 44 its low expression in all genotypes (WT and HAS-deficient) combined with no detectable change in the total HA concentration or stainable HA of the tendon, is consistent with the findings on post-translational control of HAS2 via protein glycosylation 45 and UDP precursor supply. 46 Therefore, to further our understanding of the function of HA metabolism in tendon cell proliferation and differentiation, and in ECM organization, the regulation of HAS2 catalytic activity 45,[47][48][49] and the auxillary roles of HAS1 and HAS3 proteins 50 should be explored.…”

PFKFB4 Promotes Breast Cancer Metastasis via Induction of Hyaluronan Production in a p38-Dependent Manner

“…UTP increases the phosphorylation of p38, ERK, and Ser-727 of STAT3 in human keratinocytes. p38, ERK, and STAT3 inhibitors partially block the activation of HAS2 expression which confirms the involvement of these pathways in the UTP-induced HAS2 response [42]. In this study, we found that PFKFB4 induces p38 and ERK phosphorylation, but not STAT3 or Akt phosphorylation.…”

Extracellular ATP activates hyaluronan synthase 2 (HAS2) in epidermal keratinocytes via P2Y2, Ca2+ signaling, and MAPK pathways

“…As extracellular nucleotides are similarly released after tissue injury, it is relevant to ask, whether these processes could be linked. Previous data on the effects of nucleosides and nucleotides on hyaluronan metabolism are scarce, but adenosine is known to upregulate HAS1 expression and hyaluronan secretion in gingival fibroblasts [36] and smooth muscle cells [37], while UDP-Glc, UTP and UDP enhance HAS2 expression and hyaluronan synthesis in keratinocytes [38,39].…”

“…Intriguingly, if the expression of A 2A dominates, which can occur in stressed tissues [77] or malignancies [78], activation of p38 signaling could increase the expression of HAS2, as observed in keratinocytes [35,39], and actually lead to increased hyaluronan production.…”