고포도당이 백서 사구체 메산지움 배양세포에서 p38 MAPK 활성화 및 fibronectin 생성에 미치는 영향

Abstract

Background : The p38 mitogen-activated protein kinase (MAPK) pathway is activated by several stress factors, potentially leading to cellular apoptosis and growth. Little is known about the pattern of p38 MAPK pathway activation in mesangial cells under high glucose conditions. We examined the activity and expression of p38 MAPK members, 1x78 MAPK, MAPK kinase 3/6 (MKK3/6), c-AMP responsive element binding protein (CREE), and MAPK phosphatase-l (MKP-1) in cultured rnesangial cells exposed to high glucose. Methods : Mesangial cells were subcultured from rat glomeruli isolated by sieving technique. After serum restriction for 48 hours rnesangial cells were exposed to 5.6 mM glucose (low glucose, LG), 5.6 mM glucose+24.4 mM mannitol (LG+M), or 30 mM glucose (high glucose, HG) for 3 minutes to 48 hours with or without SU203580. Western blot was performed to determine the activity and protein expression of p38 MAPK members. R`I-I`CR and ELISA were performed for fibronectin mRNA expression and fibronectin synthesis, respectively. Results : p38 MAPK and CREB activities were significantly increased in rnesangial cells exposed to FIG compared with LG or LG+M after 10 minutes and was sustained at higher levels to 48 hours (p<0.05), but total p38 MAPK and CREB protein expressions did not differ. MKP--1 showed a similar pattern as p 3 MAPK and CREE (p<O.O.i). MKK3/6 acitvity was significantly higher in HG cells after 3 minutes and remained at higher levels throught the study period (p<0.05). Fibronectin mRNA expression and fibronectin synthesis were significantly increased in mesangial cells exposed to HG after 48 hours (p<0.05). SB203580 (1 pM) pretreatment for 1 hour significantly reduced HG-induced fibronectin mRNA expression and fibronectin synthesis by 73% and 69%, respectively (p<0.05). Conclusion : p38 MAPK activity was increased in mesangial cells exposed to HG in parallel with increased MKK3/6 activity, resulting in CREB activation and increased fibronectin synthesis. This activated p38 MAPK may play a role in the pathogenesis of diabetic nephropathy.