Abstract:

Liu Xinxin*, Luo Suju, Zheng Yan, Xu Wenjuan, Li Ying, Liu Quanzhong. *Department of Dermatology, Tianjin Medical University General Hospital, Tianjin 300052, China Corresponding author: Luo Suju, Email: luosuju2005@163.com 【Abstract】 Objective To investigate the mechanisms underlying interleukin-22 （IL-22）-induced expression of heparin-binding epidermal growth factor-like growth factor （HB-EGF） in HaCaT cells. Methods Some HaCaT cells were divided into several inverention groups treated with IL-22 at concentrations of 12.5, 25, 50, 100 μg/L, respectively and a control group treated with phosphate buffer saline （PBS）. After 24-hour culture, total proteins were extracted from the HaCaT cells, and Western blot was performed to measure the expression of phosphorylated extracellular signal-regulated kinase 1/2 （P-ERK1/2） in the mitogen-activated protein kinase （MAPK）-ERK1/2 pathway, as well as phosphorylated-JAK2 （P-JAK2） and phosphorylated-signal transducer and activator of transcription 3 （P-STAT3） in the JAK2/STAT3 pathway. In a blocking experiment, some HaCaT cells were divided into 4 groups to be treated with PBS, IL-22, PD98059 （an inhibitor of MAPK-ERK1/2） combined with IL-22 （PD98059 group）, AG490 （an inhibitor of JAK2/STAT3） combined with IL-22（AG490 group）, respectively. After 24-hour treatment, total proteins and mRNAs were extracted from the HaCaT cells followed by Western blot and real-time quantitative reverse transcription-PCR for the measurement of protein and mRNA expressions of HB-EGF respectively. Statistical analysis was carried out with the software SPSS 16.0 by one-way analysis of variance （ANOVA） for intergroup comparisons and by Bonferroni′s test for multiple comparisons. Results After treatment with IL-22 at the above 4 concentrations, the expressions of P-ERK1/2, P-JAK2 and P-STAT3 in HaCaT cells were all increased compared with the control group （all P < 0.05）. The protein and mRNA expression levels （expressed as the HB-EGF/β-actin ratio and 2-△△Ct respectively） of HB-EGF were both significantly decreased in the PD98059 group and AG490 group than in the IL-22 group （protein: 0.183 ± 0.020 and 0.199 ± 0.011 vs. 0.924 ± 0.032, F = 37.700, 36.400, respectively, both P < 0.05; mRNA: 1.034 ± 0.072 and 0.989 ± 0.038 vs. 1.844 ± 0.135, F = 11.271, 13.429, respectively, both P < 0.05）. Conclusions IL-22 can activate the MAPK-ERK1/2 and JAK2/STAT3 signaling pathways in HaCaT cells, which may contribute to IL-22-induced expression of HB-EGF in HaCaT cells.