Abstract
Hyaluronan (HA) is an extracellular matrix glycosaminoglycan that critically supports the physicochemical and mechanical properties of the skin. Here, we demonstrate that mycosporine-like amino acids (MAAs), which typically function as UV-absorbing compounds, can stimulate HA secretion from normal human fibroblasts. MAA-stimulated HA secretion was associated with significantly increased and decreased levels of mRNAs encoding HA synthase 2 (HAS2) and the HA-binding protein involved in HA depolymerization (designated HYBID), respectively. Using immunoblotting, we found that MAAs at 10 and at 25 μg/ml stimulate the phosphorylation of the mitogen-activated protein kinase (MAPK) p38, extracellular signal-regulated kinase (ERK)/c-Jun, and mitogen- and stress-activated protein kinase 1 (MSK1) (at Thr-581, Ser-360, and Ser-376, respectively) and activation of cAMP-responsive element-binding protein (CREB) and activating transcription factor 2 (ATF2), but not phosphorylation of JUN N-terminal kinase (JNK) or NF-κB (at Ser-276 or Ser-536, respectively), and increased c-Fos protein levels. Moreover, a p38-specific inhibitor, but not inhibitors of MAPK/ERK kinase (MEK), JNK, or NF-κB, significantly abrogated the increased expression of HAS2 mRNA, accompanied by significantly decreased MAA-stimulated HA secretion. These results suggested that the p38-MSK1-CREB-c-Fos-transcription factor AP-1 (AP-1) or the p38-ATF2 signaling cascade is responsible for the MAA-induced stimulation of HAS2 gene expression. Of note, siRNA-mediated ATF2 silencing failed to abrogate MAA-stimulated HAS2 expression, and c-Fos silencing abolished the increased expression of HAS2 mRNA. Our findings suggest that MAAs stimulate HA secretion by up-regulating HAS2 mRNA levels through activation of an intracellular signaling cascade consisting of p38, MSK1, CREB, c-Fos, and AP-1.
Highlights
Hyaluronan (HA) is an extracellular matrix glycosaminoglycan that critically supports the physicochemical and mechanical properties of the skin
We found that mycosporine-like amino acids (MAAs) at 10 and at 25 g/ml stimulate the phosphorylation of the mitogen-activated protein kinase (MAPK) p38, extracellular signal-regulated kinase (ERK)/ c-Jun, and mitogen- and stress-activated protein kinase 1 (MSK1) and activation of cAMP-responsive element-binding protein (CREB) and activating transcription factor 2 (ATF2), but not phosphorylation of JUN N-terminal kinase (JNK) or NF-B, and increased c-Fos protein levels
A p38-specific inhibitor, but not inhibitors of MAPK/ERK kinase (MEK), JNK, or NF-B, significantly abrogated the increased expression of HA synthase 2 (HAS2) mRNA, accompanied by significantly decreased MAA-stimulated HA secretion. These results suggested that the p38 –MSK1– CREB– c-Fos–transcription factor AP-1 (AP-1) or the p38 – ATF2 signaling cascade is responsible for the MAA-induced stimulation of HAS2 gene expression
Summary
MAAs were extracted and purified as detailed under supporting “Experimental procedures” and were identified as porphyra-334 and shinorine (Fig. 1) by HPLC/LC-mass analysis The contents of porphyra-334 and shinorine in MAAs used in this study were calculated as 88.8 and 11.2%, respectively
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have