Abstract
Background: Keratinocyte migration is essential for skin wound healing and recent studies demonstrated that microRNAs (miRNAs) are involved in the differentiation, migration and apoptosis in keratinocytes. However, the function of miR-26a in wound healing remains to be largely explored.Methods: Northern blot and quantitative reverse transcriptase PCR (qRT-PCR) were used to detect the miR-26a expression and Western blot was used to detect integrin α-5 (ITGA5), phosphatidylinositol-3-kinase (PI3K), p-PI3K, protein kinase B (AKT) and p-AKT protein expression in immortalized human keratinocyte cell line HaCaT and normal human epidermal keratinocytes (NHEK) after 2 ng/ml transforming growth factor-β1 (TGF-β1) treatment for 0, 6, 12 and 24 h. Transwell assay and Wound healing assay were introduced to measure the cell migration of HaCaT cells. TargetScan online database, luciferase reporter assay and RNA immunoprecipitation (RIP) were employed to confirm the relationship between miR-26a and ITGA5.Results: The RNA expression of miR-26a was down-regulated and ITGA5 protein expression was up-regulated by TGF-β1 treatment in HaCaT and NHEK cells in a time-dependent manner. MiR-26a overexpression inhibited the migration of HaCaT cells induced by TGF-β1 while miR-26a inhibitor enhanced the migration. ITGA5 was a downstream target mRNA and regulated by miR-26a. ITGA5 overexpression reversed the inhibitory effect of miR-26a on migration in HaCaT, while ITGA5 knockdown attenuated the stimulative effect of miR-26a inhibitor in HaCaT via PI3K/AKT signaling pathway.Conclusion: MiR-26a overexpression inhibited TGF-β1 induced HaCaT cells migration via down-regulating ITGA5 through activating the PI3K/AKT signaling pathway.
Highlights
Wound healing is a highly complex process which involves coagulation, inflammation, epithelialization, granulation tissue formation, matrix deposition and tissue remodeling [1]
We double-checked its expression in primary normal human epidermal keratinocytes (NHEK) and found that miR-26a was significantly decreased (0.76 +− 0.08-fold) starting from 6 h and reached 0.28 +− 0.03-fold on 24 h after transforming growth factor-β1 (TGF-β1) treatment
These results indicated that HaCaT cells treated with TGF-β1 was a satisfying model in vitro to mimic the primary epidermal keratinocytes under wound healing especially in the re-epithelialization and miR-26a was down-regulated in HaCaT and NHEK cells by TGF-β1 treatment in a time-dependent manner
Summary
Wound healing is a highly complex process which involves coagulation, inflammation, epithelialization, granulation tissue formation, matrix deposition and tissue remodeling [1]. Re-epithelialization is largely regulated by transforming growth factor-β (TGF-β) which may modulate the migration of keratinocytes [5] but inhibits the cell proliferation [6]. Methods: Northern blot and quantitative reverse transcriptase PCR (qRT-PCR) were used to detect the miR-26a expression and Western blot was used to detect integrin α-5 (ITGA5), phosphatidylinositol-3-kinase (PI3K), p-PI3K, protein kinase B (AKT) and p-AKT protein expression in immortalized human keratinocyte cell line HaCaT and normal human epidermal keratinocytes (NHEK) after 2 ng/ml transforming growth factor-β1 (TGF-β1) treatment for 0, 6, 12 and 24 h. MiR-26a overexpression inhibited the migration of HaCaT cells induced by TGF-β1 while miR-26a inhibitor enhanced the migration. Conclusion: MiR-26a overexpression inhibited TGF-β1 induced HaCaT cells migration via down-regulating ITGA5 through activating the PI3K/AKT signaling pathway
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