Purification and characterization of a kringle-deficit mutant of human plasminogen with Arg-Gly-Asp tripeptide expressed in Pichia pastorsis / 生物工程学报

To obtain a recombinant human plasminogen (hPLG) with potential anti-platelet aggregation activity, we cloned the cDNA coding Pro544 to Asn791 of hPLG, a kringle-deficit derivative (hPLG-deltaK). The Pro559 in activation loop was then mutated into Asp559 to provide Arg-Gly-Asp (RGD) motif. The constructed pPICZalphaA-RGD-HPLG-deltaK plasmid was expressed in yeast Pichia pastoris GS115, which produced RGD-hPLG-deltaK about 0.160 g/L broth. After affinity chromatography, the purity of the recombinant protein reached above 90%. Western blotting test confirmed that it retained the immunological reaction capability as human PLG. Its urokinase activation rate in 24 hours and its fibrinolytic activity made no deference against native hPLG-deltaK (P=0.630, n=5). Importantly, after activation by urokinase, RGD-hPLG-deltaK showed a significantly higher platelet aggregation inhibition rate (Ri) (21.8% +/- 1.57%) than hPLG-deltaK (3.8% +/- 0.33%) (P=0.000, n=5). These results proved that we constructed an hPLG mutant with anti-platelet aggregation activity, which made a foundation for developing innovative thrombolytic drugs with multifunction.

siRNA Targeting Vascular Endothelial Growth Factor and Recombinant Human Prothrombin Kringle 2 Inhibits Leukemia-induced Angiogenesis

BACKGROUND: Vascular endothelial growth factor (VEGF) plays a role in the development of cancer and the progression of liquid tumors such as chronic lymphatic leukemia, non-Hodgkin lymphomas, and multiple myeloma. VEGF also triggers endothelial cells to secrete hematopoietic growth factors such as interleukin-6 (IL-6); this in turn promotes further leukemia growth, thereby contributing to a paracrine loop between the leukemia and the endothelial cells. METHODS: We transfected a small interfering RNA (siRNA) targeting VEGF into K562 cells in order to investigate the role of VEGF in the development of leukemic cancer. After the conditioned media (CM) of the K562 was cells added to the human umbilical endothelial cell (HUVEC) culture media, we compared the proliferation and tube formation of the HUVECs. Recombinant human prothrombin kringle2 (K2), which is a known angiogenic inhibitor, was also treated onto the HUVECs, and we then examined the level of IL-6 to determine the paracrine interaction between the leukemic and endothelial cells. RESULTS: RT-PCR and western blot analysis demonstrated that the siRNA efficiently down regulated the expression of VEGF in the K562 cells. When the CM of the K562 cells was added to the HUVEC culture, the proliferation of the HUVECs was stimulated. The proliferation of the HUVEC induced by the CM from the siRNA-VEGF K562 cells was diminished, compared with that of the vector control K562 cells. K2 reduced not only the proliferation of the HUVECs, but also the secretion of IL-6 by the HUVEC. CONCLUSION: The siRNA strategy is an alternative tool for inhibiting leukemia-induced angiogenesis. A combinated therapy with angiogenesis inhibitor K2 increases the efficiency. K2 modulates the production of IL-6, which may affect the paracrine interaction between leukemia and endothelial cells.

Differential inhibition of endothelial cell proliferation and migration by urokinase subdomains: amino-terminal fragment and kringle domain

The serine protease urokinase-type plasminogen activator (uPA) is implicated in pericellular proteolysis in a variety of physiological and pathological processes including angiogenesis and tumor metastasis. The kringle domain of uPA (UK1) has proven to be an anti-angiogenic molecule with unknown mechanism and amino terminal fragment of uPA (u-ATF) with additional growth factor-like domain can be used for blocking interaction of uPA and uPA receptor. Here, we compared anti-angiogenic activities of these two molecules in vitro and in vivo. The recombinant u-ATF from E. coli and refolded in vitro was found to bind to uPAR with high affinity, whereas E. coli-derived UK1 showed no binding by Biacore analysis. In contrast to UK1 having potent inhibitory effect, u-ATF exhibited low inhibitory effect on bovine capillary endothelial cell growth (ED(50)>320 nM). Furthermore, u-ATF inhibition of VEGF-induced migration of human umbilical vein endothelial cell was far less sensitive (IC(50)= 600 nM) than those observed with UK1, and angiogenesis inhibition was marginal in chorioallantoic membrane. These results suggest that kringle domain alone is sufficient for potent anti- angiogenic activity and additional growth factor-like domain diverts this molecule in undergoing different mechanism such as inhibition of uPA/uPAR interaction rather than undergoing distinct anti- angiogenic mechanism driven by kringle domain.

Effects of wild-type (Trp72) and mutant (Arg72) apolipoprotein(a) kringle IV-10 on the proliferation of human arterial smooth muscle cells / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To assess the atherogenicity of lipoprotein(a), the effect of the heterogeneity of lysine binding of apolipoprotein(a) [apo(a)], a plasminogen-like glycoprotein component on the proliferation of human arterial smooth muscle cells (SMCs).</p><p><b>METHODS</b>Both wild type (wt) Trp72 and mutant (mut) Trp72-->Arg forms of apo(a) kringle IV-10 were expressed by employing a GST-gene fusion system into E. coli. The proliferation of SMCs was determined by flow cytometry and MTT colorimetry. Enzyme-linked immunosorbent assay (ELISA) assay was used to detect the active form of transforming growth factor beta(1) (TGF-beta(1)).</p><p><b>RESULTS</b>Apo(a) wt-kringle IV-10 that has lysine binding properties possessed a growth-stimulating activity to SMCs on a dose-dependence manner by stimulating cells in the G(1)/G(0) phase of cell cycle to S and G(2)/M phase, and reduced significantly the amounts of endogenous active TGF-beta(1) in culture when compared with the control medium and the GST group (2.4 +/- 0.5 vs 8.6 +/- 1.6 and 9.1 +/- 1.7 ng/ml, P < 0.01). The growth-stimulating effect of apo(a) mut-kringle IV-10 deficient in lysine binding was negligible.</p><p><b>CONCLUSIONS</b>Apo(a) induces SMCs growth by inhibiting the activation of latent TGF-beta(1), an activity that may involve the ability of apo(a) kringle IV-10 to bind lysine. The mitogenic effect of apo(a) wt-kringle IV-10 on SMCs might play an active role in the atherogenic function of lipoprotein(a).</p>

Cloning and expression of kringle 1-3 gene of human plasminogen and the purification and bioactivity of its expressed product / 生物工程学报

Kringle 1-3 domain is a recently found angiogenesis inhibitor with anti-angiogenesis and anti-tumor activity. The kringle 1-3 gene was amplified by PCR technique using angiostatin gene as template. After DNA sequencing, the PCR product was cloned into pPIC9K resulting in recombinant plasmid pPIC9K13 which was then transformed into Pichia pastoris GS115. The high copy integration transformants screened by PCR and G418 methods were cultivated in flasks. The K1-3 was expressed and secreted to the medium and has immunogenic activity as shown by SDS-PAGE and Western blotting. High cell density culture was carried out in 30-liter and 80-liter bioreactor, the biomass reaches 300 OD after methanol induction, and the expressed product is 200 mg/L. The fermentation supernatant was purified by Streamline SP and Phenyl Sepharose Chromatography, the product appears as a single band on SDS-PAGE, with a purity of 95%-96%. The purified product has anti-angiogenesis and anti-tumor activity.

Allele Frequencies of Apo(a) Pentanucleotide(TTTTA) Repeat Polymorphism / 대한임상병리학회지

BACKGROUND: Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein that is assembled from a low density lipoprotein(LDL) and apolipoprotein(a) [apo(a)]. The variations in Lp(a) concentration tend to be inversely related to the number of kringle IV in apo(a) gene, but other polymorphisms [pentanucleotide(TTTTA) repeats, +93 C/T polymorphism, and Met/Thr polymorphism] of the apo(a) gene are also seems to be related to Lp(a) concentrations. The purpose of this study was to investigate the association of the pentanucleotide repeat polymorphism(PNRP) and Met/Thr polymorphism with the Lp(a) concentrations. METHODS: We studied 197 healthy adults. For genotype analysis of the PNRP and the Met/Thr polymorphism, PCR was performed. Apo(a) phenotyping was performed by SDS-PAGE and immunoblotting. The Lp(a) concentrations were measured by ELISA method. More than two groups were compared using the Kruskal Wallis one-way analysis test. To establish a relationship between gene polymorphisms and Lp(a) concentrations, The linear regression test was performed. RESULTS: Mean Lp(a) concentration was 25.3+/-21.5 mg/dL. Allele frequencies for PNRP, subjects with 8/8 genotype were 114(57.9%) and most frequently observed. The Lp(a) concentrations showed the tendency to decrease as the sum of alleles of PNR increased. Subjects with Met/Thr genotype were 119(60.4%), Met/Met genotype were 71(36.0%) and Thr/Thr genotype were 7(3.6%). CONCLUSIONS: For PNRP, subjects with 8/8 genotype were 114(57.9%) and 8/8 genotype was the most frequently observed. Met/Thr genotype was most frequently observed.

cDNA Cloning and Expression of Angiostatin, an Angiogenesis Inhibitor , from Human Liver Tissue mRNA / 대한암학회지

PURPOSE: Angiostatin, a 38 kDa internal fragment of plasminogen, is a potent inhibitor of angiogenesis. It blocks neovascularization and growth of primary and metastatic tumors in mice. To produce recombinant angiostatin protem comprising kringle 1-4 of plasminogen, we cloned the angiostatin cDNA from human liver tissue mRNA and expressed it in E. coli. MATERIALS AND METHODS: We cloned angiostatin cDNA from human liver tissue mRNA using reverse transcriptase polymerase chain reaction (RT-PCR) method. Cloned cDNA was ligated to pET22b (+) expression vector, transformed into E. coli stram BL21 (DE3) and expressed by IPTG induction. Recombinant human angiostatin protein was purified from the inclusion bodies of lysated bacterial pellet with 8 M urea solubilization, refolding, single step Lysine-Sepharose 4B affinity chromatography and 0.2 M E-aminocarproic acid elution. The anti-angiogenic activity of purified recombinant angiostatin was assayed with endothelial cell proliferation assay and chorioallantoic membrane assay (CAM). RESULTS: The identification of cloned angiostatin cDNA was confirmed by Southern hybridization and Pst I restriction enzyme digestion pattern. Angiostatin cDNA was expressed in E. coli, refolded in vitro and purified by Lysine Sepharose 4B affinity chromatography. The molecular weight of purified recombinant angiostatin was about 55 kDa on the SDS-PAGE. It inhibited the proliferation of bovine capillary endothelial (BCE) cells in vitro with a half-maximal inhibition concentration (ED50) of approximately 500 ng/mL. It also suppressed neovasculrization on the CAM assay. CONCLUSION: These results demonstrated that recombinant human angiostatin has similar function and biological activity compared with human angiostatin which is purified from porcine elastase digested human plasminogen fragment.

The inhibitory effects of recombinant plasminogen kringle 1-3 on the neovascularization of rabbit cornea induced by angiogenin, bFGF, and VEGF

Angiostatin is a potent angiogenesis inhibitor that is composed of the first four kringles of plasminogen fragment. Angiostatin with one less kringle molecule (kringle 1 to 3) was recently demonstrated to be an effective angiogenic inhibitor. To determine whether recombinant plasminogen kringle 1-3 (rPK1-3) can inhibit the corneal neovascularization induced by potent angiogenic factors; angiogenin, bFGF, or VEGF, hydron polymer discs each containing 2.0 microg of angiogenin, 500 ng of bFGF, or 500 ng of VEGF respectively were implanted into the corneal stroma of 138 rabbit eyes, and then discs each containing 10 microg, 12.5 microg, 20 microg or 30 microg of rPK1-3 were implanted randomly. Discs containing phosphate buffered saline were also implanted as a control. The angiogenesis score on number and length of newly formed vessels on the each of the rabbit's cornea were recorded daily by two observers (blinded). The treated corneas were also examined histologically. Recombinant PK1-3 treated corneas showed less neovascularization induced by all angiogenic factors (p < 0.05). and the extent of inhibition of neovascularization was proportional to the concentration of rPK1-3 (p < 0.05). Histologic examination showed leukocyte infiltration into the corneal stroma on the PBS treated eyes whereas rPK1-3 treated eyes showed only traces of leukocytes. These results of the effective rPK1-3 inhibition of corneal neovascularization induced by angiogenin, bFGF, or VEGF suggest that this angiostatin related fragment, rPK1-3, may be useful in the treatment of various neovascular diseases. Copyright 2000 Academic Press.