Endothelin-1-mediated signaling in the expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in astrocytes.
OBJECTIVE
Endothelin (ET)-1 levels are increased in aqueous and vitreous humor in patients with glaucoma and animal models of glaucoma. Whether the elevated ET-1 induces extracellular matrix (ECM) remodeling in the optic nerve head is still unknown. In the present study, the regulation of matrix metalloproteinases/tissue inhibitors of matrix metalloproteinases (MMPs/TIMPs) and ECM remodeling in ET-1-activated human optic nerve head astrocytes (hONAs) were determined.


METHODS
Primary hONAs were exposed to ET-1 for 1 day and 4 days. Incubation media were subjected to zymography and Western blot to detect activity and expression of MMPs and TIMPs. Fibronectin (FN) was monitored by Western blot and immunofluorescent staining.


RESULTS
ET-1 increased the activity of MMP-2 and the expression of TIMP-1 and -2 in hONAs. The expression of TIMP-1 and -2 induced by ET-1 was abolished by application of inhibitors of mitogen-activated protein kinase (MAPK) or PKC, leading to enhanced activity of MMP-2. Knockdown of MMP-2, by using small interfering (si)RNA, not only decreased the activity of MMP-2 but also decreased the expression of TIMP-1 and -2. ET-1 increased the soluble (s)FN expression as well as FN matrix formation. However, the accumulation of sFN did not enhance FN matrix formation. Unlike ET-1's effects on MMP-2, blockade of MAPK and PKC did not alter the expression and deposition pattern of FN in hONAs.


CONCLUSIONS
ET-1 increased the expression and activity of MMP-2 and TIMP-1 and -2. The ERK-MAPK and PKC pathways are involved in the regulation of expression of MMP-2 and TIMP-1 and -2. ET-1's effects on MMPs/TIMPs may be important, not only in regulating the expression of MMPs and TIMPs, but also in influencing ECM remodeling.
He
Shaoqing
S
Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107, USA.
Prasanna
Ganesh
G
Yorio
Thomas
T
D000368:Aged; D001253:Astrocytes / Q000166:cytology / Q000201:enzymology*; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000378:metabolism* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D005901:Glaucoma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009898:Optic Disk / Q000166:cytology / Q000201:enzymology; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D064546:Protein Kinase C beta; D051745:Protein Kinase C-delta / Q000378:metabolism; D034741:RNA, Small Interfering; D012995:Solubility; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000378:metabolism*
D019332:Endothelin-1; D004791:Enzyme Inhibitors; D005353:Fibronectins; D034741:RNA, Small Interfering; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051745:Protein Kinase C-delta; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020778:Matrix Metalloproteinase 2