Inducible expression of calreticulin-N58 in Pichia pastoris by high density cell culture

Constitutive expression of the active fragment of human vasostatin Vs30 in Pichia pastoris SMD1168H

Vasostatin 30 (Vs30) is an active fragment derived from the N-terminal region (135-164 aa) of human calreticulin and has the ability to inhibit angiogenesis. In this work, the expression of Vs30 was performed using a protease-deficient strain of the methylotrophic yeast Pichia pastoris. The vs30 gene was optimized for P. pastoris preferential codon usage and inserted into constitutive expression vector pGAPZαA. In addition, a plasmid with four copies of the expression cassette was obtained and transformed into P. pastoris. The flask fermentation conditions were: culture volume of 25 mL in 250 mL baffled flasks at 28 °C, pH 6 and harvest time of 48 h. Up to 21.07 mg/L Vs30 were attained and purified by ultrafiltration with a 30-kDa cut-off membrane and the recovery was 49.7%. Bioactivity of Vs30 was confirmed by the inhibition of cell proliferation, as well as the inhibition of the capillary-like structures formation of EA.hy926 cells in vitro. This work constitutes the first report on the expression of Vs30 in Pichia pastoris using a constitutive promoter and multi-copy approach such as strategies to improve the recombinant Vs30 expression.

Scl gene construction, expression and effect on hemangioma

Hemangioma is a tumor that causes vascular endothelial cell hyperplasia, which commonly occur in newborns. Angiogenesis inhibitor targets the processes of angiogenesis, including the proliferation of vascular endothelial cells. A DNA sequence named Scl was designed, recombined into Pichia Pastoris, expressed by fermenting the engineered strain in a bioreactor, and purified the recombinant Scl by SP-sepharose fast flow. Scl can inhibit CAM angiogenesis. Only 1 μg of Scl significantly suppressed the growth of CAM blood vessel, similar to that of 25 μg of angiostatin. Scl showed a strong cytotoxicity on hemangioma cell (ATCC CRL No. 2587). After the drug acted for 24 h, the OD 570 measured value of the PBS control group averaged 1.873, whereas that of the Sc1 drug group was 0.692 (P < 0.01). Using the DeadEndTM Fluorometric TUNEL System, the detection results showed that 92 % of hemangioma cell apoptosis was observed in the Scl protein group, but only 1.3 % in the PBS control group (P < 0.01). After 2 weeks of treatment with the hemangioma model (cock's wattle) of the PBS group, 151 blood vessels with 100 views (40×) were obtained, whereas 250 in the PBS group (P < 0.01). During the two-week medication, the hemangioma model of the PBS group increased by 1.18 cm, whereas only 0.58 cm in the Scl drug group (P < 0.01).