High glucose induces MCP-1 expression partly via tyrosine kinase-AP-1 pathway in peritoneal mesothelial cells.
BACKGROUND
High glucose in peritoneal dialysis solutions has been implicated in the pathogenesis of peritoneal fibrosis in chronic ambulatory peritoneal dialysis (CAPD) patients. However, the mechanisms are not very clear. Peritoneal macrophages seem to participate in the process of peritoneal fibrosis and monocyte chemoattractant protein-1 (MCP-1) plays a key role in the recruitment of monocytes toward the peritoneal cavity. However, little is known about the effect of high glucose on MCP-1 expression and its signal transduction pathway in human peritoneal mesothelial cells.


METHODS
Mesothelial cells were cultured with glucose (5 to 100 mmol/L) or mannitol chronically for up to seven days. MCP-1 expression of mRNA and protein was measured by Northern blot analysis and enzyme-linked immunosorbent assay (ELISA). Chemotactic activity of high-glucose-conditioned culture supernatant was measured by chemotactic assay. To examine the roles of the transcription factors activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB), electrophoretic mobility shift assay (EMSA) was performed.


RESULTS
Glucose induced MCP-1 mRNA expression in a time- and dose-dependent manner. MCP-1 protein in cell culture supernant was also increased. Equivalent concentrations of mannitol had no significant effect. High-glucose-conditioned supernatant possessed an increased chemotactic activity for monocytes, which was neutralized by anti-MCP-1 antibody. EMSA revealed that glucose increased the AP-1 binding activity in a time- and dose-dependent manner, but not NF-kappaB. Curcumin, an inhibitor of AP-1, dose-dependently suppressed the induction of MCP-1 mRNA by high glucose. Tyrosine kinase inhibitors such as genistein (12.5 to 50 micromol/L) and herbimycin A (0.1 to 1 micromol/L) inhibited the high-glucose-induced MCP-1 mRNA expression in a dose-dependent manner, and also suppressed the high-glucose-induced AP-1 binding activity.


CONCLUSIONS
: High glucose induced mesothelial MCP-1 expression partly via the tyrosine kinase-AP-1 pathway.
Lee
S K
SK
Department of Internal Medicine, and Asan Institute for Life Sciences, University of Ulsan, College of Medicine, Seoul, Korea.
Kim
B S
BS
Yang
W S
WS
Kim
S B
SB
Park
S K
SK
Park
J S
JS
D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000008:administration & dosage* / Q000494:pharmacology; D006801:Humans; D008353:Mannitol / Q000494:pharmacology; D009000:Monocytes / Q000502:physiology; D010537:Peritoneum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism* / Q000502:physiology
D018932:Chemokine CCL2; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D008353:Mannitol; D011505:Protein-Tyrosine Kinases; D005947:Glucose