title: Downregulation of CD9 in keratinocyte contributes to cell migration via upregulation of matrix metalloproteinase-9.
abstract: Tetraspanin CD9 has been implicated in various cellular and physiological processes, including cell migration. In our previous study, we found that wound repair is delayed in CD9-null mice, suggesting that CD9 is critical for cutaneous wound healing. However, many cell types, including immune cells, endothelial cells, keratinocytes and fibroblasts undergo marked changes in gene expression and phenotype, leading to cell proliferation, migration and differentiation during wound repair, whether CD9 regulates kerationcytes migration directly remains unclear. In this study, we showed that the expression of CD9 was downregulated in migrating keratinocytes during wound repair in vivo and in vitro. Recombinant adenovirus vector for CD9 silencing or overexpressing was constructed and used to infect HaCaT cells. Using cell scratch wound assay and cell migration assay, we have also demonstrated that downregulation of CD9 promoted keratinocyte migration in vitro, whereas CD9 overexpression inhibited cell migration. Moreover, CD9 inversely regulated the activity and expression of MMP-9 in keratinocytes, which was involved in CD9-regulated keratinocyte migration. Importantly, CD9 silencing-activated JNK signaling was accompanied by the upregulation of MMP-9 activity and expression. Coincidentally, we found that SP600125, a JNK pathway inhibitor, decreased the activity and expression of MMP-9 of CD9-silenced HaCaT cells. Thus, our results suggest that CD9 is downregulated in migrating keratinocytes in vivo and in vitro, and a low level of CD9 promotes keratinocyte migration in vitro, in which the regulation of MMP-9 through the JNK pathway plays an important role.
authors.affiliation: Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China.
authors.forename: Xu-pin
authors.initials: XP
authors.lastname: Jiang
authors.forename: Dong-xia
authors.initials: DX
authors.lastname: Zhang
authors.forename: Miao
authors.initials: M
authors.lastname: Teng
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhang
authors.forename: Jia-ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Yue-sheng
authors.initials: YS
authors.lastname: Huang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D060888:Real-Time Polymerase Chain Reaction; D060245:Tetraspanin 29 / Q000235:genetics / Q000378:metabolism*
chemical_list: D060245:Tetraspanin 29; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9