Ultra Violet (UV) radiation induces reactive oxygen species (ROS) production, DNA oxidation and single strand breaks (SSBs), which will eventually lead to skin cell damages or even skin cancer. Here, we tested the potential activity of gremlin, a novel vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) agonist, against UV-induced skin cell damages. We show that gremlin activated VEGFR2 and significantly inhibited UV-induced death and apoptosis of skin keratinocytes and fibroblasts. Pharmacological inhibition or shRNA-mediated knockdown of VEGFR2 almost abolished gremlin-mediated cytoprotection against UV in the skin cells. Further studies showed that gremlin activated VEGFR2 downstream NF-E2-related factor 2 (Nrf2) signaling, which appeared required for subsequent skin cell protection. Nrf2 shRNA knockdown or S40T dominant negative mutation largely inhibited gremlin-mediated skin cell protection against UV. At last, we show that gremlin dramatically inhibited UV-induced ROS production and DNA SSB formation in skin keratinocytes and fibroblasts. We conclude that gremlin protects skin cells from UV damages via activating VEGFR2-Nrf2 signaling. Gremlin could be further tested as a novel anti-UV skin protectant.

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Metal-responsive transcription factor 1 (MTF-1) regulates a variety of genes involving in metal homeostasis and oxidative stress. We have shown that MTF-1 can be conjugated by small ubiquitin-like modifier (SUMO) and forms complexes with cellular factor(s) in a SUMO-interacting motif (SIM)-dependent manner. To investigate whether the interaction of MTF-1 and its SUMO conjugate occurs, we expressed and isolated MTF-1 and sumoylated MTF-1 (S-MTF-1) for functional studies. Various conditions were examined to optimize the expressions of MTF-1 and S-MTF-1. Results from affinity column chromatography demonstrated that the unmodified MTF-1 consistently co-eluted with the S-MTF-1. Mutations at the SIM did not reduce the level of MTF-1 sumoylation but the sumoylated product can then be purified to homogeneity. The presence of MTF-1 cross-interaction was further supported by in vitro pull-down assays. The ability of the purified proteins in binding metal-responsive element (MRE) was assessed with electrophoretic mobility shift assay. Noticeably, MTF-1 required the presence of cell extracts to render the binding activity. However, S-MTF-1 binds MRE in void of other cellular factors. The same characteristic was found for MTF-1 with SUMO fusion at the carboxyl terminus. These results indicate that the presence of SUMO moiety allows the protein to interact directly with MRE.

Acute generalized exanthematous pustulosis is a severe, usually drug-related reaction, characterized by an acute onset of mainly small non-follicular pustules on an erythematous base. Most cases of acute generalized exanthematous pustulosis (AGEP) clear quickly with a systemic corticosteroid, but severe or recalcitrant cases may need other systemic therapies. In this case, a man in his 40 s with a history of psoriasis consulted a physician about widespread erythema, pustules, target lesions, and fever after the administration of a quadruple antituberculosis drug. Routine laboratory testing revealed elevated white blood cell count and C-reactive protein. The histopathology showed subcorneal pustules, spongiosis as well as lymphocyte and eosinophils infiltration in the dermis. The patient was diagnosed with definitive AGEP according to the diagnostic score from the EuroSCAR study. Cutaneous lesions especially pustules and erythema multiforme-like lesions on the upper arms and palms are crucial for distinguishing AGEP from Generalized pustular psoriasis. The patient was treated with secukinumab as a result of his failure to respond to topical corticosteroids and constrain of systemic steroids. Remission with secukinumab therapy was safe without increased risks of infections. This case indicates that secukinumab is a potential therapy that can rapidly improve the clinical symptoms of AGEP.

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