[ICAM-1 regulates differentiation of MSC to adipocytes via activating MAPK pathway]

This study was aimed to explore the molecular mechanism of the regulatory effects of ICAM-1 on the differentiation of mesenchymal stem cells (MSC) to adipocytes. The murine MSC cell line C3H10T 1/2 was treated with the supernatants contained plasmid MIGR1-ICAM-1 and MIGR1-ICAM-1/MSC (high expression of ICAM-1), the activation of the pathway was detected by Western blot. The ICAM-1 modified MSC and its control cells named MIGR1/MSC were cultured in adipocyte medium with or without the inhibitors of the ERK, P38, and JNK pathway. Oil-red-O staining was used to detect the lipid accumulation, and the expression of C/EBPα and PPARγ in differentiation of MSC to adipocyte were examined by real-time-PCR. The results showed that the overexpression of ICAM-1 stably activated the ERK, P38, and JNK pathway in MSC. Inhibiting of the activation of ERK pathways by chemical inhibitors up-regulated the mRNA expression level of C/EBPα and PPARγ in MIGR1-ICAM-1/MSC while inhibiting of P38 pathway resulted in lower mRNA expression of the transcription factors. Consistent with the mRNA expression, the lipid droplets were getting smaller and number of adipocytes increased when P38 pathway was inhibited, while bigger lipid droplet and increased quantity of adipocytes were identified in MIGR1-ICAM-1/MSC with the addition of ERK pathway inhibitor. It is concluded that ICAM-1 may suppress MSC differentiate into adipocyte via activating ERK pathway, while it can maintain the adipogenesis of MSC though P38 pathway.