Abstract
Human glomerular epithelial cells (GECs) in culture synthesize single‐chain, urokinase‐type plasminogen activator (SC‐uPA), tissue‐type plasminogen activator (t‐PA), and plasminogen activator inhibitor 1 (PAI‐1) and possess specific membrane‐binding sites for u‐PA. Using purified 125I‐alpha thrombin, we demonstrate here the presence of two populations of specific binding sites for thrombin on GECs (1.Kd = 4.3 ± 1.0 × 10−10 M, 5.4 ± 1.4 × 104 M sites per cell, 2. Kd = 1.6 ± 0.5 × 10−8 M, 7.9 ± 1.8 × 105 sites per cell). Purified human alpha thrombin promoted the proliferation of GECs and induced a time‐and dose‐dependent increase of SC‐uPA, t‐PA, and PAI‐1 antigens released by GECs. Thrombin‐mediated increase in antigen was paralleled by an increase in the levels of corresponding u‐PA and PAI‐1 messenger RNA. In contrast, thrombin decreased u‐PA activity in conditioned medium. This discrepancy between u‐PA antigen and u‐PA activity was explained by a limited proteolysis of SC‐uPA by thrombin, leading to a two‐chain form detected by immunoblotting and that could not be activated by plasmin. Thrombin also decreased the number of u‐PA binding sites on GECs (p < 0.05) without changing receptor affinity. Hirudin inhibited the binding and the cellular effects of thrombin, whereas thrombin inactivated by diisopropylfluorophosphate had no effect, indicating that both membrane binding and catalytic activity of thrombin were required. We conclude that thrombin, through specific membrane receptors, stimulates proliferation of GECs and decreases the fibrinolytic activity of GECs both at the cell surface and in the conditioned medium. These results suggest that thrombin could be involved in the pathogenesis of extracapillary proliferation and persistency of fibrin deposits in crescentic glomerulonephritis.
| Original language | English |
|---|---|
| Pages (from-to) | 131-140 |
| Number of pages | 10 |
| Journal | Journal of Cellular Physiology |
| Volume | 146 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Jan 1991 |
| Externally published | Yes |
Cite this
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Thrombin increases proliferation and decreases fibrinolytic activity of kidney glomerular epithelial cells. / He, Ci‐Jiang ‐J; Rondeau, Eric; Medcalf, Robert L.; Lacave, Roger; Schleuning, Wolf‐Dieter ‐D; Sraer, Jean‐Daniel ‐D.
In: Journal of Cellular Physiology, Vol. 146, No. 1, 01.01.1991, p. 131-140.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Thrombin increases proliferation and decreases fibrinolytic activity of kidney glomerular epithelial cells
AU - He, Ci‐Jiang ‐J
AU - Rondeau, Eric
AU - Medcalf, Robert L.
AU - Lacave, Roger
AU - Schleuning, Wolf‐Dieter ‐D
AU - Sraer, Jean‐Daniel ‐D
PY - 1991/1/1
Y1 - 1991/1/1
N2 - Human glomerular epithelial cells (GECs) in culture synthesize single‐chain, urokinase‐type plasminogen activator (SC‐uPA), tissue‐type plasminogen activator (t‐PA), and plasminogen activator inhibitor 1 (PAI‐1) and possess specific membrane‐binding sites for u‐PA. Using purified 125I‐alpha thrombin, we demonstrate here the presence of two populations of specific binding sites for thrombin on GECs (1.Kd = 4.3 ± 1.0 × 10−10 M, 5.4 ± 1.4 × 104 M sites per cell, 2. Kd = 1.6 ± 0.5 × 10−8 M, 7.9 ± 1.8 × 105 sites per cell). Purified human alpha thrombin promoted the proliferation of GECs and induced a time‐and dose‐dependent increase of SC‐uPA, t‐PA, and PAI‐1 antigens released by GECs. Thrombin‐mediated increase in antigen was paralleled by an increase in the levels of corresponding u‐PA and PAI‐1 messenger RNA. In contrast, thrombin decreased u‐PA activity in conditioned medium. This discrepancy between u‐PA antigen and u‐PA activity was explained by a limited proteolysis of SC‐uPA by thrombin, leading to a two‐chain form detected by immunoblotting and that could not be activated by plasmin. Thrombin also decreased the number of u‐PA binding sites on GECs (p < 0.05) without changing receptor affinity. Hirudin inhibited the binding and the cellular effects of thrombin, whereas thrombin inactivated by diisopropylfluorophosphate had no effect, indicating that both membrane binding and catalytic activity of thrombin were required. We conclude that thrombin, through specific membrane receptors, stimulates proliferation of GECs and decreases the fibrinolytic activity of GECs both at the cell surface and in the conditioned medium. These results suggest that thrombin could be involved in the pathogenesis of extracapillary proliferation and persistency of fibrin deposits in crescentic glomerulonephritis.
AB - Human glomerular epithelial cells (GECs) in culture synthesize single‐chain, urokinase‐type plasminogen activator (SC‐uPA), tissue‐type plasminogen activator (t‐PA), and plasminogen activator inhibitor 1 (PAI‐1) and possess specific membrane‐binding sites for u‐PA. Using purified 125I‐alpha thrombin, we demonstrate here the presence of two populations of specific binding sites for thrombin on GECs (1.Kd = 4.3 ± 1.0 × 10−10 M, 5.4 ± 1.4 × 104 M sites per cell, 2. Kd = 1.6 ± 0.5 × 10−8 M, 7.9 ± 1.8 × 105 sites per cell). Purified human alpha thrombin promoted the proliferation of GECs and induced a time‐and dose‐dependent increase of SC‐uPA, t‐PA, and PAI‐1 antigens released by GECs. Thrombin‐mediated increase in antigen was paralleled by an increase in the levels of corresponding u‐PA and PAI‐1 messenger RNA. In contrast, thrombin decreased u‐PA activity in conditioned medium. This discrepancy between u‐PA antigen and u‐PA activity was explained by a limited proteolysis of SC‐uPA by thrombin, leading to a two‐chain form detected by immunoblotting and that could not be activated by plasmin. Thrombin also decreased the number of u‐PA binding sites on GECs (p < 0.05) without changing receptor affinity. Hirudin inhibited the binding and the cellular effects of thrombin, whereas thrombin inactivated by diisopropylfluorophosphate had no effect, indicating that both membrane binding and catalytic activity of thrombin were required. We conclude that thrombin, through specific membrane receptors, stimulates proliferation of GECs and decreases the fibrinolytic activity of GECs both at the cell surface and in the conditioned medium. These results suggest that thrombin could be involved in the pathogenesis of extracapillary proliferation and persistency of fibrin deposits in crescentic glomerulonephritis.
UR - http://www.scopus.com/inward/record.url?scp=0026029437&partnerID=8YFLogxK
U2 - 10.1002/jcp.1041460117
DO - 10.1002/jcp.1041460117
M3 - Article
VL - 146
SP - 131
EP - 140
JO - Journal of Cellular Physiology
JF - Journal of Cellular Physiology
SN - 0021-9541
IS - 1
ER -