ABSTRACT
Objective To clone and express the extracellular portion of mouse Fcγreceptor Ⅱ-b ( FcγRⅡb) and to analyze the functions of the expressed proteins in a mouse model of systemic lupus ery-thematosus ( SLE) .Methods The gene fragment encoding FcγRⅡb was amplified by PCR, and then in-serted into the prokaryotic expression vector pET-32a(+) to construct the recombinant expression plasmid pET-FcγRⅡb.The expression plasmid was identified with restriction enzymes and then sent to the Shanghai Bio-Engineering Co.LTD for further sequencing analysis.The transformed Escherichia coli ( E.coli) BL21 ( DE3) strains carrying the recombinant expression plasmid pET-FcγRⅡb were induced by isopropylβ-D-1-thiogalactoside ( IPTG) .The expressed fusion proteins were analyzed by Western blot assay and purified with purification kits.The immune complex ( IC)-binding ability of FcγRⅡb was measured by ELISA.MRL/lpr mice with SLE in both the prevention (12 weeks old, n=40) and the treatment groups (19 weeks old, n=40) were randomly divided into four groups including 60 μl (4.8 μg) treatment group, 120 μl (9.6 μg) treatment group, 180μl (14.4μg) treatment group and PBS treatment group with 10 mouse in each group. The MRL/lpr mice with SLE were injected with the fusion protein through tail vein once a week for four con-secutive weeks.Serum samples were collected from each mouse after one week of observation.The levels of FcγRⅡb in soluble form in mice form both the prevention and treatment groups as well as the levels of anti-double stranded DNA antibodies were detected by ELISA.Results The gene encoding FcγRⅡb was ampli-fied and the recombinant expression plasmid pET-FcγRⅡb was successfully constructed.The recombinant proteins were expressed in the prokaryotic expression system, and then successfully purified.The recombi-nant proteins could bind to IC.Compared with the corresponding PBS control group, the levels of FcγRⅡb in soluble form were increased in mice from both prevention and treatment groups after treating with various concentrations of the recombinant protein (P<0.05).Significant differences in the levels of FcγRⅡb were found among mice of the same age after treating with different concentrations of the recombinant protein ( P<0.05).Compared with the corresponding PBS control group, the levels of anti-double stranded DNA anti-bodies were decreased in mice from both prevention and treatment groups after treating with various concen-trations of the recombinant protein (P<0.05).The levels of anti-double stranded DNA antibodies were grad-ually decreased along with the increasing dosage of protein (P<0.05).Conclusion The extracellular por-tion of murine FcγRⅡb in soluble form was successfully expressed.The recombinant proteins played a cer-tain role in the prevention and treatment of SLE in a mouse model.
ABSTRACT
Objective To construct an eukaryotic vector expressing short hairpin RNA(shRNA) of HIF-1α,and to observe its effects on location and metastasis of HeLa cells under hypoxic condition.Methods shRNA templates was developed based on HIF-1α gene sequence and then cloned into pSilencer2.1-U6-neo vector.The resultant plasmid was transfected into HeLa cells with Lipofectamine 2000.The cells were incubated in hypoxic condition.The HIF-1α protein and mRNA were detected by Western blot and RT-PCR.The colony formation assay and Transwell cabin assay were performed to measure the colony formation and metastasis.Results The plasmid pSilencer2.1-U6-neo-HIF-1α was successfully constructed and transfected into HeLa cells.The expression of HIF-1α in HeLa cells decreased,and the number of colony formation in soft agar and cells penetrating matrigel also decreased under hypoxic condition.Conclusion The shRNA expressing plasmid targeting at HIF-1α may suppress the location and metastasis of cervical carcinoma cells under hypoxic condition.