Volume 63, Issue 3, Pages 958-968 (March 2003) High glucose activates the p38 MAPK pathway in cultured human peritoneal mesothelial cells  Zhong-Gao Xu, Kyung Sik Kim, Hyeong Cheon Park, Kyu Hun Choi, Ho Yung Lee, Dae Suk Han, Shin-Wook Kang  Kidney International  Volume 63, Issue 3, Pages 958-968 (March 2003) DOI: 10.1046/j.1523-1755.2003.00836.x Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 1 Western blot of total and phospho-specific p38 mitogen-activated protein kinase (MAPK) in human peritoneal mesothelial cells (HPMCs) exposed to low glucose (LG) and high gluclose (HG) for 3 minutes to 48 hours (representative of four blots). Phospho-specific p38 MAPK protein expression (upper panel) was significantly higher in HPMCs exposed to high glucose than in those exposed to low glucose at 10 minutes and sustained to 48 hours. Densitometric quantitation revealed an average 1.9-fold increase in phospho-specific p38 MAPK expression in HPMCs under high glucose conditions versus low glucose conditions after 10 minutes (P < 0.05). Total p38 MAPK protein expression (lower panel) was not different between the two groups. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 2 High glucose stimulates p38 mitogen-activated protein kinase (MAPKP mRNA expression in human peritoneal mesothelial cells (HPMCs). (A) A representative p38 MAPK reverse transcription-polymerase chain reaction (RT-PCR) electrophoresis of high glucose (HG) and low glucose (LG) cells at 3, 10, and 30 minutes, and 2, 24, and 48 hours (N = 4). Compared to low glucose, p38 MAPK mRNA expression was significantly increased in high glucose cells at all the indicated times after 10 minutes. (B) There was a significant increment in p38 MAPK/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA in HPMCs exposed to high glucose () than those exposed to low glucose (□) after 10 minutes. *P < 0.05 vs. low glucose. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 3 Western blot of phospho-specific mitogen-activated protein kinase (MAPK) kinase 3/6 (MKK3/6) in human peritoneal mesotheial cells (HPMCs) exposed to low glucose (LG) and high glucose (HG) for 3 minutes to 48 hours (representative of four blots). Phospho-specific MKK3/6 protein expression was significantly higher in HPMCs exposed to high glucose than in those exposed to low glucose throughout the study period. Densitometric quantitation revealed that there was an average 2.2-fold increase in phospho-specific MKK3/6 expression in high glucose cells compared with low glucose cells (P < 0.05). There was no difference in total MKK3 protein expression between low glucose and high glucose cells. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 4 High glucose stimulates mitogen-activated protein kinase (MAPK) kinase 3 (MKK3) and MKK6 mRNA expression in human peritoneal mesothelial cells (HPMCs). A representative MKK3 and MKK6 reverse transcription-polymerase chain reaction (RT-PCR) electrophoresis of high glucose (HG) and low glucose (LG) cells at 3, 10, and 30 minutes, and 2, 24, and 48 hours (N = 4). MKK3 and MKK6 mRNA expression was significantly higher in HPMCs incubated in high glucose than in those exposed to low glucose. Average 2.1- and 1.7-fold increments in MKK3 and MKK6 mRNA expressions were observed in high glucose versus low glucose cells, respectively (P < 0.05). Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 5 Western blot of phospho-specific cyclic adenosine monophosphate (cAMP)-responsive element-binding (CREB) protein in human peritoneal mesothelial cells (HPMCs) exposed to low glucose (LG) and high glucose (HG) for 3 minutes to 48 hours (representative of four blots). Phospho-specific CREB protein expression was significantly higher in HPMCs exposed to high glucose than in those exposed to low glucose at 10 minutes, and sustained to 48 hours. Densitometric quantitation revealed an average 2.3-fold increase in phospho-specific CREB expression in high glucose–cultured HPMCs versus low glucose–cultured HPMCs after 10 minutes (P < 0.05). Total CREB protein expression in high glucose cells was not different from that in low glucose cells. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 6 High glucose stimulates cyclic adenosine monophosphate (cAMP)-responsive element-binding (CREB) protein mRNA expression in human peritoneal mesothelial cells (HPMCs). (A) A representative CREB reverse transcription-polymerase chain reaction (RT-PCR) electrophoresis of high glucose (HG) and low glucose (LG) cells at 3, 10 and 30 minutes, and 2, 24, and 48 hours (N = 4). Compared to low glucose, CREB mRNA expression was significantly increased in high glucose cells at all the indicated time points after 10 minutes. (B) A significant increment in CREB/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA was observed in HPMCs exposed to high glucose () as compared to those exposed to low glucose (□) after 10 minutes. *P < 0.05 vs. low glucose. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 7 High glucose stimulates fibronectin mRNA expression in human peritoneal mesothelial cells (HPMCs). (A) A representative fibronectin competitive reverse transcription-polymerase chain reaction (RT-PCR) electrophoresis of low glucose (LG) and high glucose (HG) cells at 24 hours (N = 4). Each lane represents a competitive RT-PCR reaction (38 cycles) with a fixed amount of fibronectin wild-type cDNA (451 bp) from the equivalent of 10 ng RNA and a variable amount of fibronectin competitor cDNA (313 bp) as follows: lane 1, 50 amol/μL; lane 2, 10 amol/μL; lane 3, 5 amol/μL; lane 4, 1 amol/μL, and lane 5, 0.5 amol/μL. (B) A significant increase in fibronectin mRNA expression was observed in high glucose–cultured () HPMCs versus low glucose-cultured (□) HPMCs after 2 hours. *P < 0.05 vs. low glucose. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 8 Western blot of mitogen-activated protein kinase (MAPK) phosphatase (MKP-1) in human peritoneal mesothelial cells (HPMCs) exposed to low glucose (LG) and high glucose (HG) for 3 minutes to 48 hours (representative of four blots). MKP-1 protein expression was significantly lower in HPMCs exposed to high glucose than in those exposed to low glucose at all the indicated times after 10 minutes. Densitometric quantitation revealed that there was an average 57% decrease in MKP-1 expression in HPMCs cultured under high glucose conditions versus those cultured under low glucose conditions after 10 minutes (P < 0.05). Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 9 High glucose inhibits mitogen-activated protein kinase (MAPK) phosphatase (MKP-1) mRNA expression in human peritoneal mesothelial cells (HPMCs). (A) A representative MKP-1 reverse transcription-polymerase chain reaction (RT-PCR) electrophoresis of high glucose (HG) and low glucose (LG) cells at 3, 10, and 30 minutes, and 2, 24, and 48 hour (N = 4). Compared to low glucose cells, MKP-1 mRNA expression was significantly lower in high glucose cells at 10 minutes, and remained at a lower level to 48 hours. (B) A significant decrease in MKP-1/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA was observed in HPMCs exposed to high glucose () as compared to those exposed to low glucose (□) after 10 minutes. *P < 0.05 vs. low glucose. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 10 Western blot of phospho-specific p38 mitogen-activated protein kinase (MAPK) and phospho-specific cyclic adenosine monophosphate (cAMP)-responsive element-binding (CREB) protein in human peritoneal mesothelial cells (HPMCs) with or without p38 MAPK inhibitor for 24 hours (representative of five blots). (A) The p38 MAPK inhibitor, SB203580, inhibited high glucose (HG)–induced p38 MAPK activity in a dose-dependent manner. Densitometric quantitation revealed that the phospho-specific p38 MAPK level was reduced by 84% with 1 μmol/L SB203580 pretreatment for an hour. Total p38 MAPK protein expression did not change with SB203580. LG is low glucose. (B) Pretreatment with 1 μmol/L SB203580 for 1 hour also significantly reduced high glucose (HG)–induced CREB activity in HPMCs by 89% (P < 0.05). Low glucose (LG) + mannitol had no effect on p38 MAPK or CREB activity. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions

Figure 11 The p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 inhibits fibronectin mRNA expression in human peritoneal mesothelial cells (HPMCs) exposed to high glucose (HG) for 24 hours. Pretreatment with 1 μmol/L SB203580 (SB) for 1 hour significantly inhibited high glucose–induced fibronectin mRNA expression in HPMCs by 75% (N = 4). Low glucose (LG) + mannitol (M) had no effect on fibronectin mRNA expression in HPMCs. *P < 0.05 vs. low gluclose; #P < 0.05 vs. high glucose. Kidney International 2003 63, 958-968DOI: (10.1046/j.1523-1755.2003.00836.x) Copyright © 2003 International Society of Nephrology Terms and Conditions