Serotonin enhances the production of type IV collagen by human mesangial cells.
BACKGROUND
The plasma concentration of 5-hydroxytryptamine (5-HT) in diabetic patients is higher than that in normal subjects. Since recent reports have demonstrated the presence of 5-HT2A receptor in glomerular mesangial cells, it is possible that 5-HT may be involved in the development of diabetic nephropathy through the 5-HT2A receptor in mesangial cells. Because expansion of the glomerular mesangial lesion is a characteristic feature of diabetic nephropathy, we examined the effect of 5-HT on the production of type IV collagen by human mesangial cells.


METHODS
Human mesangial cells were incubated with 5-HT with or without 5-HT receptor antagonists, protein kinase C (PKC) inhibitor or transforming growth factor-beta (TGF-beta) antibody. Type IV collagen mRNA and protein concentration in medium were measured by Northern blot analysis and enzyme-linked immunosorbent assay (ELISA), respectively. TGF-beta mRNA and bioactivity in the medium were measured by Northern blot analysis and bioassay using mink lung epithelial cells, respectively.


RESULTS
5-HT stimulated the production of type IV collagen by human mesangial cells, which was inhibited by ketanserin and sarpogrelate hydrochloride, 5-HT2A receptor antagonists, but not by ondansetron, a 5-HT3 receptor antagonist. 5-HT increased the bioactivities of both active and total TGF-beta. However, the 5-HT-enhanced production of type IV collagen was completely inhibited by an anti-TGF-beta antibody. Furthermore, a PKC inhibitor, calphostin C, inhibited the 5-HT-induced increase in type IV collagen secretion, and the activity of membrane PKC was increased by 5-HT. Phorbol ester activated type IV collagen production as well as active and total TGF-beta. Calphostin C completely inhibited the 5-HT-enhanced activity of active TGF-beta, but did not inhibit exogenous TGF-beta-induced increase in type IV collagen secretion.


CONCLUSIONS
Our results suggest that 5-HT-enhanced production of type IV collagen by human mesangial cells is mediated by activation of PKC and subsequent increase in active TGF-beta activity.
Department of Metabolic Medicine, Kumamoto University School of Medicine, Honjo, Japan.
M
M
Kasho
M
M
Sakai
T
T
Sasahara
Y
Y
Anami
T
T
Matsumura
T
T
Takemura
H
H
Matsuda
S
S
Kobori
M
M
Shichiri
D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis*; D003928:Diabetic Nephropathies / Q000209:etiology / Q000378:metabolism; D005920:Glomerular Mesangium / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007650:Ketanserin / Q000494:pharmacology; D007700:Kinetics; D011493:Protein Kinase C / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013386:Succinates / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013386:Succinates; D016212:Transforming Growth Factor beta; C064294:sarpogrelate; D012701:Serotonin; D003094:Collagen; D007650:Ketanserin; D011493:Protein Kinase C