The multiple-step cleavage of amyloid precursor protein (APP) generates amyloid-β peptides (Aβ), highly toxic molecules causing Alzheimer's disease (AD). The nonspecific cleavage between the transmembrane region of APP (APPTM) and γ-secretase is the key step of Aβ generation. Reconstituting APPTM under physiologically-relevant conditions is crucial to investigate how it interacts with γ-secretase and for future AD drug discovery. Although producing recombinant APPTM was reported before, the large scale purification was hindered by the use of biological protease in the presence of membrane protein. Here, we expressed recombinant APPTM in Escherichia coli using the pMM-LR6 vector and recovered the fusion protein from inclusion bodies. By combining Ni-NTA chromatography, cyanogen bromide cleavage, and reverse phase high performance liquid chromatography (RP-HPLC), isotopically-labeled APPTM was obtained in high yield and high purity. The reconstitution of APPTM into dodecylphosphocholine (DPC) micelle generated mono dispersed 2D ¹⁵N-¹H HSQC spectra in high quality. We successfully established an efficient and reliable method for the expression, purification and reconstruction of APPTM, which may facilitate future investigation of APPTM and its complex in more native like membrane mimetics such as bicelle and nanodiscs.
Humans ; Amyloid beta-Protein Precursor/chemistry* ; Micelles ; Amyloid Precursor Protein Secretases/metabolism* ; Magnetic Resonance Spectroscopy ; Recombinant Proteins

Objective To investigate the preventive therapeutic effect and possible mechanism of single chain variable fragments chimeric protein (SD) of ovalbumin epitopes internalizing receptor DEC-205 antibody on food allergy in mice. Methods Mice were randomly divided to five groups (control, PBS, scFv DEC 100 μg, SD 50 μg, SD 100 μg) and treated for 24 hours before OVA administration. After challenge, the serum level of OVA-specific IgE, IgG1, IgG2a and IL-4 were detected by ELISA. Infiltration of eosinophils and mast cells in the jejunum was observed by HE staining and toluidine blue staining respectively. The bone marrow of tibia and femur was isolated and cultured to obtain immature dendritic cells(BMDCs), which were further treated with LPS (10 ng/mL), TSLP (50 ng/mL), scFv DEC protein (1000 ng/mL) and SD protein (10,100,1000)ng/mL for 24 hours, and the IL-10 level of supernatant was assayed by ELISA. Results Compared with PBS group, the number of SD-treated mice with diarrhea was markedly reduced. The difference in rectal temperature and the levels of serum OVA-specific IgE, IgG1, IgG2a and IL-4 decreased significantly after prophylactic administration of SD; The number of eosinophils and mast cells in jejunum also decreased significantly while the IL-10 level in the supernatant of BMDCs increased significantly after SD intervention. Conclusion SD mitigates experimental FA response by fosters the immune tolerance property of dendritic cells.
Mice ; Animals ; Ovalbumin ; Interleukin-10 ; Single-Chain Antibodies/genetics* ; Immunoglobulin E ; Epitopes/therapeutic use* ; Interleukin-4 ; Food Hypersensitivity/prevention & control* ; Immunoglobulin G ; Recombinant Fusion Proteins/genetics* ; Mice, Inbred BALB C ; Disease Models, Animal

Objective To prepare a rabbit anti-mouse coiled-coil domain containing 189 (Ccdc189) polyclonal antibody. Methods The pET-28a-Ccdc189 prokaryotic expression plasmid was constructed and transformed into E.coli BL21. IPTG was used to induce the expression of Ccdc189 prokaryotic protein. Adult male New Zealand rabbits were immunized with purified recombinant protein to obtain rabbit anti-mouse Ccdc189 polyclonal antibody. The specificity of the polyclonal antibody was identified by Western blot analysis, indirect ELISA and immunofluorescence histochemical staining. Results The pET-28a-Ccdc189 recombinant plasmid was successfully constructed and the expression of the Ccdc189 recombinant protein was induced. ELISA revealed that the titer of the polyclonal antibody was 1:1 000 000. Western blot and immunofluorescence staining demonstrated that the Ccdc189 polyclonal antibody could specifically identify the Ccdc189 prokaryotic protein and the Ccdc189 protein in adult wild-type mouse testis. Conclusion A polyclonal antibody with high specificity against mouse Ccdc189 was successfully created.
Rabbits ; Male ; Animals ; Mice ; Antibody Specificity ; Antibodies ; Enzyme-Linked Immunosorbent Assay ; Blotting, Western ; Recombinant Proteins ; Escherichia coli/genetics*

Objective To express the monkeypox virus (MPXV) A23R protein in Escherichia coli and purify by Ni-NTA affinity column, and to prepare mouse antiserum against MPXV A23R. Methods The recombinant plasmid pET-28a-MPXV-A23R was constructed and transformed into Escherichia coli BL21 to induce the expression of A23R protein. After optimizing the conditions of expression, A23R protein was highly expressed. Recombinant A23R protein was purified by Ni-NTA affinity column and identified by Western blot analysis. The purified protein was used to immunize mice for preparing the A23R polyclonal antibody, and the antibody titer was detected by ELISA. Results The expression of A23R recombinant protein reached the peak under the induced conditions of 0.6 mmol/L isopropyl-β-D-thiogalactoside (IPTG), 37 DegreesCelsius and 20 hours. The purity of the protein was about 96.07% and was identified by Western blot analysis. The mice were immunized with recombinant protein, and the titer of antibody reached 1:102 400 at the 6th week after immunization. Conclusion MPXV A23R is expressed highly and purified with a high purity and its antiserum from mouse is obtained with a high titre.
Animals ; Mice ; Monkeypox virus ; Antibodies ; Enzyme-Linked Immunosorbent Assay ; Blotting, Western ; Recombinant Proteins ; Escherichia coli/genetics*

OBJECTIVE: To investigate the effect and relative mechanism of Recombinant Human Thrombopoietin (rhTPO) on long-term hematopoietic recovery in mice with acute radiation sickness. METHODS: Mice were intramuscularly injected with rhTPO (100 μg/kg) 2 hours after total body irradiation with ⁶⁰Co γ-rays (6.5 Gy). Moreover, six months after irradiation, peripheral blood, hematopoietic stem cells (HSC) ratio, competitive transplantation survival rate and chimerization rate, senescence rate of c-kit⁺ HSC, and p16 and p38 mRNA expression of c-kit⁺ HSC were detected. RESULTS: Six months after 6.5 Gy γ-ray irradiation, there were no differences in peripheral blood white blood cells, red blood cells, platelets, neutrophils and bone marrow nucleated cells in normal group, irradiated group and rhTPO group (P>0.05). The proportion of hematopoietic stem cells and multipotent progenitor cells in mice of irradiated group was significantly decreased after irradiation (P<0.05), but there was no significant changes in rhTPO group (P>0.05). The counts of CFU-MK and BFU-E in irradiated group were significantly lower than that in normal group, and rhTPO group was higher than that of the irradiated group(P<0.05). The 70 day survival rate of recipient mice in normal group and rhTPO group was 100%, and all mice died in irradiation group. The senescence positive rates of c-kit⁺ HSC in normal group, irradiation group and rhTPO group were 6.11%, 9.54% and 6.01%, respectively (P<0.01). Compared with the normal group, the p16 and p38 mRNA expression of c-kit⁺ HSC in the irradiated mice were significantly increased (P<0.01), and it was markedly decreased after rhTPO administration (P<0.01). CONCLUSION The hematopoietic function of mice is still decreased 6 months after 6.5 Gy γ-ray irradiation, suggesting that there may be long-term damage. High-dose administration of rhTPO in the treatment of acute radiation sickness can reduce the senescence of HSC through p38-p16 pathway and improve the long-term damage of hematopoietic function in mice with acute radiation sickness.
Humans ; Mice ; Animals ; Thrombopoietin/metabolism* ; Hematopoietic Stem Cells ; Blood Platelets ; Recombinant Proteins/therapeutic use* ; Radiation Injuries ; RNA, Messenger/metabolism*

SARS-CoV-2-induced immune thrombocytopenia (SARS-CoV-2-induced ITP) is an autoimmune disease secondary to virus infections. Its diagnosis is often based on exclusion of other possible causes of thrombocytopenia in COVID-19 patients. Common laboratory examinations include coagulation function, thrombopoietin and drug-dependent antibodies. Since both bleeding and thrombosis risks are seen in SARS-CoV-2-induced ITP patients, individual remedy is essential for the treatment of this disease. Because thrombopoietin receptor agonist(TPO-RA) has the side effect of accelerating thrombosis and may aggravate the pulmonary embolism symptoms of patients, it should be used for refractory SARS-CoV-2-induced ITP patients only. This review briefly summarizes the recent research progress in the pathogenesis, diagnosis and treatment of SARS-CoV-2-induced ITP.
Humans ; Purpura, Thrombocytopenic, Idiopathic/drug therapy* ; SARS-CoV-2 ; COVID-19/complications* ; Thrombocytopenia ; Thrombosis/drug therapy* ; Thrombopoietin/therapeutic use* ; Recombinant Fusion Proteins/therapeutic use*

Objective: To observe the clinical effect of Qiliqiangxin capsule combined with recombinant human brain natriuretic peptide in acute left heart failure patients 7 days after onset as well as the effects of plasma MDA and ET-1. Methods: In total, 240 hospitalized patients with acute left heart failure from October 2017 to May 2021 were selected from the Department of Emergency and Critical Care Center of Beijing Anzhen Hospital, Capital Medical University and the Department of Cardiology of the Jilin Provincial People's Hospital. They were randomly divided into routine treatment group and combined treatment group, with 120 cases in each group. The routine treatment group was treated with vasodilation, diuresis, cardiotonic and recombinant human brain natriuretic peptide. The combined treatment group was treated with Qiliqiangxin capsules based on the routine treatment group. One week later, the changes in clinical efficacy, ejection fraction, left ventricular commoid diameter, and plasma BNP, MDA, and ET-1 were compared between the two groups before and after treatment. SPSS 11.5 statistical software was used. The measurement data was expressed in x¯±s, the independent sample t-test was used for comparison between groups, and the paired t-test was used for comparison before and after treatment within groups. Counting data was expressed as case (%), and the rank sum test was used for inter-group comparison. Result: In terms of clinical efficacy, the total effective rate of the combined treatment group was significantly higher than that of the conventional treatment group, and the difference was statistically significant (P<0.05). Compared with the routine treatment group, the left ventricular ejection fraction in the combined treatment group was significantly increased (P<0.05). The levels of plasma BNP, MDA and ET-1 were significantly decreased (P<0.05). Conclusion: Qiliqiangxin capsule combined with rhBNP treatment can effectively improve the clinical symptoms of acute heart failure, as well as reduce the lipid peroxidation product MDA content and endothetin ET-1 level in blood. The clinical application value of the Qiliqiangxin capsule needs to be further confirmed by further trials.
Humans ; Heart Failure/physiopathology* ; Natriuretic Peptide, Brain/therapeutic use* ; Stroke Volume/physiology* ; Ventricular Function, Left/physiology* ; Cardiotonic Agents/therapeutic use* ; Drugs, Chinese Herbal/therapeutic use* ; Recombinant Proteins/therapeutic use* ; Cardiovascular Agents/therapeutic use* ; Drug Therapy, Combination

OBJECTIVE: To explore the effect of recombinant human thrombopoietin (rhTPO) on hematopoietic reconstruction in allogeneic hematopoietic stem cell transplantation (allo-HSCT) model. METHODS: The C57BL/6 mice were employed as the donors, and BALB/c mice as recipients. The bone marrow mononuclear cells of the donor mice were extracted and pretreated, which then were injected with 5×10⁶ per mouse through the tail vein of the recipient to establish an allo-HSCT model. The implantation of hematopoietic stem cells in the recipient mice was detected by flow cytometry on the 28^th day after transplantation. Next, the successfully modeled recipient mice were randomly divided into experimental group and control group. The rhTPO was injected into mice in the experimental group on the first day after transplantation, while the saline was injected into mice in the control group. Both groups were injected for 14 consecutive days. The peripheral blood and bone marrow hematopoiesis of the two groups were observed on day 1, 3, 7, 14, and 21 after transplantation. RESULTS: The expression rate of H-2K^b in the bone marrow of recipient mice was 43.85% (>20%) on the 28^th day after transplantation, which indicated that the recipient mice were successfully chimerized. Meanwhile, counts of PLTs on the day 3, 7, 14, and 21 after transplantation in the experimental group were higher than those in the control group with statistical significances (P<0.05). In addition, hematopoietic function of bone marrow was suppressed in both groups on day 1, 3 and 7 after transplantation, but hematopoietic bone marrow hyperplasia was better in the experimental group than in the control group. On day 14 and 21 after transplantation, the hematopoietic function of bone marrow in the two groups was recovered, and the experimental group showed more obvious than the control group. CONCLUSION rhTPO can effectively stimulate the production of PLTs and facilitate the recovery of white blood cells and hemoglobin after allo-HSCT, and promote hematopoietic recovery and reconstitution of bone marrow.
Humans ; Animals ; Mice ; Thrombopoietin ; Mice, Inbred C57BL ; Hematopoietic Stem Cell Transplantation ; Hematopoietic Stem Cells ; Bone Marrow ; Recombinant Proteins ; Mice, Inbred BALB C

Chinese hamster ovary (CHO) cells play an irreplaceable role in biopharmaceuticals because the cells can be adapted to grow in suspension cultures and are capable of producing high quality biologics exhibiting human-like post-translational modifications. However, gene expression regulation such as transgene silencing and epigenetic modifications may reduce the recombinant protein production due to the decrease of expression stability of CHO cells. This paper summarized the role of epigenetic modifications in CHO cells, including DNA methylation, histone modification and miRNA, as well as their effects on gene expression regulation.
Cricetinae ; Animals ; Humans ; Cricetulus ; CHO Cells ; Epigenesis, Genetic/genetics* ; DNA Methylation ; Gene Expression Regulation ; Recombinant Proteins/genetics*

Papaya, which is mainly cultivated in the southeastern region of China, is one of the four famous fruits in Lingnan. It is favored by people because of its edible and medicinal value. Fructose-6-phosphate, 2-kinase/fructose-2, 6-bisphosphatase (F2KP) is a unique bifunctional enzyme with a kinase domain and an esterase domain that catalyzes the synthesis and degradation of fructose-2, 6-bisphosphate (Fru-2, 6-P₂), an important regulator of glucose metabolism in organisms. In order to study the function of the gene CpF2KP encoding the enzyme in papaya, it is particularly important to obtain the target protein. In this study, the coding sequence (CDS) of CpF2KP, with a full-length of 2 274 bp, was got from the papaya genome. The amplified sequence of full-length CDS was cloned into the vector PGEX-4T-1 which was double digested with EcoR I and BamH I. The amplified sequence was constructed into a prokaryotic expression vector by genetic recombination. After exploring the induction conditions, the results of SDS-PAGE showed that the size of the recombinant GST-CpF2KP protein was about 110 kDa. The optimum IPTG concentration and temperature for CpF2KP induction were 0.5 mmol/L and 28 ℃, respectively. The purified sin[A1] gle target protein was obtained after purifying the induced CpF2KP protein. In addition, the expression level of this gene was detected in different tissues, and showed that the gene was expressed at the highest level in seeds and the lowest in pulp. This study provides an important basis for further revealing the function of CpF2KP protein and studying the involved biological processes of this gene in papaya.
Humans ; Carica/genetics* ; Recombinant Proteins ; Carbohydrate Metabolism ; Cloning, Molecular ; China