Calcium spirulan as an inducer of tissue-type plasminogen activator in human fetal lung fibroblasts.
Calcium spirulan (Ca-SP), a novel sulfated polysaccharide isolated from the blue-green alga Spirulina platensis, has been found to have antiviral and heparin cofactor II-dependent antithrombin activities. We have obtained evidence that Ca-SP is a potent inducer of tissue-type plasminogen activator (t-PA) production. The addition of Ca-SP to a culture of IMR-90 human fetal lung fibroblasts increased t-PA concentrations in the conditioned medium, in a dose- and time-dependent manner, but in the cell lysate, t-PA concentrations were unchanged, suggesting that t-PA induced by Ca-SP is easily secreted into the conditioned medium. The amount of newly synthesized t-PA in IMR-90 cells, as measured by labeling with [35S]methionine and subsequent immunoprecipitation of t-PA from conditioned medium, was significantly increased by Ca-SP-stimulation. However, Ca-SP did not increase the t-PA mRNA levels. As previously reported, thrombin stimulated t-PA gene transcription in IMR-90 cells, and the simultaneous treatment with Ca-SP and thrombin caused further enhancement of t-PA production, in a synergistic manner. It would thus appear that Ca-SP increases t-PA production through post-transcriptional processes. IMR-90 cells also produce plasminogen activator inhibitor type-1 (PAI-1), but Ca-SP showed little effect on the PAI-1 production. H-SP, which was obtained by removing the calcium from Ca-SP, had no effect on the t-PA production. Na-SP, which was prepared by replacement of the calcium with sodium, stimulated the t-PA production similarly to Ca-SP. Thus, Ca-SP specifically induces t-PA production, and the molecular conformation of Ca-SP maintained by Ca or Na may be essential for the stimulation of t-PA synthesis.
Hayakawa
Y
Y
Department of Clinical Laboratory Medicine, Faculty of Medicine, Toyama, Japan. hayakawa@ms.toyama-mpu.ac.jp
Hayashi
T
T
Hayashi
K
K
Ozawa
T
T
Niiya
K
K
Sakuragawa
N
N
D015152:Blotting, Northern; D002460:Cell Line; D017077:Culture Media, Conditioned; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005333:Fetus; D005347:Fibroblasts; D006801:Humans; D008168:Lung; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D011134:Polysaccharides / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000096:biosynthesis* / Q000235:genetics
D017077:Culture Media, Conditioned; D017395:Plasminogen Activator Inhibitor 1; D011134:Polysaccharides; D012333:RNA, Messenger; C102617:spirulan; D013917:Thrombin; D010959:Tissue Plasminogen Activator