Open AccessMLK 3 is a novel target of dehydroglyasperin D for the reduction in UVB ‐induced COX ‐2 expression in vitro and in vivo
Author(s) -
Jung Sung Keun,
Ha Su Jeong,
Kim Yeong A,
Lee Jihoon,
Lim TaeGyu,
Kim Yun Tai,
Lee Nam Hyouck,
Park Jun Seong,
Yeom MyeongHun,
Lee Hyong Joo,
Lee Ki Won
Publication year - 2015
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/jcmm.12311
Subject(s) - hacat , protein kinase a , kinase , microbiology and biotechnology , p38 mitogen activated protein kinases , mapk/erk pathway , chemistry , phosphorylation , biology , biochemistry , in vitro
Dehydroglyasperin D ( DHGA ‐D), a compound present in licorice, has been found to exhibit anti‐obesity, antioxidant and anti‐aldose reductase effects. However, the direct molecular mechanism and molecular targets of DHGA ‐D during skin inflammation remain unknown. In the present study, we investigated the effect of DHGA ‐D on inflammation and its mechanism of action on UVB ‐induced skin inflammation in HaCaT human keratinocytes and SKH ‐1 hairless mice. DHGA ‐D treatment strongly suppressed UVB ‐induced COX ‐2 expression, PGE 2 generation and AP ‐1 transactivity in HaCaT cells without affecting cell viability. DHGA ‐D also inhibited phosphorylation of the mitogen‐activated protein kinase kinase ( MKK ) 3/6/p38, MAPK /Elk‐1, MKK 4/c‐Jun N‐terminal kinase ( JNK ) 1/2/c‐Jun/mitogen, and stress‐activated protein kinase ( MSK ), whereas phosphorylation of the mixed‐lineage kinase ( MLK ) 3 remained unaffected. Kinase and co‐precipitation assays with DHGA ‐D Sepharose 4B beads showed that DHGA ‐D significantly suppressed MLK 3 activity through direct binding to MLK 3. Knockdown of MLK 3 suppressed COX ‐2 expression as well as phosphorylation of MKK 4/p38 and MKK 3/6/ JNK 1/2 in HaCaT cells. Furthermore, Western blot assay and immunohistochemistry results showed that DHGA ‐D pre‐treatment significantly inhibits UVB ‐induced COX ‐2 expression in vivo . Taken together, these results indicate that DHGA ‐D may be a promising anti‐inflammatory agent that mediates suppression of both COX ‐2 expression and the MLK 3 signalling pathway through direct binding and inhibition of MLK 3.