Sulfonium-Stapled Peptides-Based Neoantigen Delivery System for Personalized Tumor Immunotherapy and Prevention.

Neoantigen peptides hold great potential as vaccine candidates for tumor immunotherapy. However, due to the limitation of antigen cellular uptake and cross-presentation, the progress with neoantigen peptide-based vaccines has obviously lagged in clinical trials. Here, a stapling peptide-based nano-vaccine is developed, comprising a self-assembly nanoparticle driven by the nucleic acid adjuvant-antigen conjugate. This nano-vaccine stimulates a strong tumor-specific T cell response by activating antigen presentation and toll-like receptor signaling pathways. By markedly improving the efficiency of antigen/adjuvant co-delivery to the draining lymph nodes, the nano-vaccine leads to 100% tumor prevention for up to 11 months and without tumor recurrence, heralding the generation of long-term anti-tumor memory. Moreover, the injection of nano-vaccine with signal neoantigen eliminates the established MC-38 tumor (a cell line of murine carcinoma of the colon without exogenous OVA protein expression) in 40% of the mice by inducing potent cytotoxic T lymphocyte infiltration in the tumor microenvironment without substantial systemic toxicity. These findings represent that stapling peptide-based nano-vaccine may serve as a facile, general, and safe strategy to stimulate a strong anti-tumor immune response for the neoantigen peptide-based personalized tumor immunotherapy.

Clinical characteristics, diagnosis and management of nivolumab-induced myocarditis.

Nivolumab can cause fatal myocarditis. We aimed to analyze the clinical characteristics of nivolumab-induced myocarditis and provide evidence for clinical diagnosis, treatment, and prevention. Studies involving nivolumab-induced myocarditis were identified in electronic databases from 2000 to 2023 for retrospective analysis. A total of 66 patients were included, with a median age of 68 years. The median onset time of myocarditis is 11.5 days. The main organs affected in persons presented with myocarditis are heart (100.0%) and skeletal muscle (22.7%). The main clinical manifestations are dyspnea (49.2%), fatigue (47.6%), and myalgias (25.4%). The levels of troponin, troponin T, troponin I, creatine kinase, creatine kinase myocardial band, creatine phosphokinase, C-reactive protein, brain natriuretic peptide, and N-terminal brain natriuretic peptide precursor were significantly increased. Histopathology often shows lymphocyte infiltration, myocardial necrosis, and fibrosis. Myocardial immunological parameters usually present positive. Cardiac imaging often suggests complete heart block, intraventricular conduction delay, arrhythmia, myocardial infarction, edema, left ventricular ejection fractions reduction, ventricular dysfunction, and other symptoms of myocarditis. Forty-two (63.6%) patients achieved remission within a median time of 8 days after discontinuation of nivolumab and treatment with systemic corticosteroids, immunoglobulins, plasmapheresis, and immunosuppressant. Thirty-five patients eventually died attributed to myocarditis (68.6%), cancer (20.0%), respiratory failure (5.7%), and other reasons (5.7%). Nivolumab-induced myocarditis should be comprehensively diagnosed based on clinical symptoms, histopathological manifestations, immunological parameters, and cardiac function imaging examinations. Nivolumab should be discontinued immediately, plasmapheresis and systemic corticosteroids combined with immunoglobulins or immunosuppressants may be an effective treatment.

Direct structure determination of vemurafenib polymorphism from compact spherulites using 3D electron diffraction.

The spherulitic morphology is considered to be the most common morphology of crystalline materials and is particularly apparent in melt-crystallized products. Yet, historically, the polycrystalline nature of spherulites has hindered successful crystal structure determination. Here, we report the direct structure determination of a clinical drug, vemurafenib (VMN), in compact spherulite form using 3D electron diffraction (3D ED). VMN has four known polymorphs. We first solved the crystal structures of α-, ß-, and γ-VMN from compact spherulites using 3D ED, and the resulting structures were highly consistent with those obtained by single-crystal X-ray diffraction. We then determined the crystal structure of δ-VMN-the least stable polymorph which cannot be cultivated as a single crystal-directly from the compact spherulite sample. We unexpectedly discovered a new polymorph during our studies, denoted as ε-VMN. Single crystals of ε-VMN are extremely thin and not suitable for study by X-ray diffraction. Again, we determined the structure of ε-VMN in a compact spherulite form. This successful structure elucidation of all five VMN polymorphs demonstrates the possibility of directly determining structures from melt-grown compact spherulite samples. Thereby, this discovery will improve the efficiency and broaden the scope of polymorphism research, especially within the field of melt crystallization.

miR-582 Suppresses the Proliferation of B-Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL) Cells and Protects Them From Natural Killer Cell-Mediated Cytotoxicity.

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a malignancy characterized by the aberrant accumulation of immature B-cell precursors in bone marrow and other lymphoid organs. Although several intrinsic regulatory signals participating in BCP-ALL have been clarified, detailed intrinsic and extrinsic mechanisms that regulate BCP-ALL progression have not been fully understood. In the current study, we report that miR-582 is downregulated in BCP-ALL cells compared with normal B cells. Forced overexpression of miR-582 attenuated BCP-ALL cell proliferation and survival. We found that miR-582 overexpression disturbed the mitochondrial metabolism of BCP-ALL cells, leading to less ATP but more ROS production. Mechanistically, we identified PPTC7 as a direct target of miR-582. MiR-582 overexpression inhibited the activity of CoQ10, which is downstream of PPTC7 and played an important positive regulatory role in mitochondrial electron transportation. Finally, we found that overexpression of miR-582 upregulated the expression of immune checkpoint molecule CD276 and reduced NK cell-mediated cytotoxicity against BCP-ALL cells. CD276 blockade significantly increased NK cell-mediated cytotoxicity against miR-582-overexpressing BCP-ALL cells. Together, our research demonstrates that miR-582 acts as a negative regulator of BCP-ALL cells by reducing proliferation and survival, but protects BCP-ALL cells from NK cell-mediated cytotoxicity, suggesting that miR-582 may be a new therapeutic biomarker for BCP-ALL with CD276 blocker.

Variant analyses of candidate genes in orofacial clefts in multi-ethnic populations.

OBJECTIVES: Cleft lip with/without cleft palate and cleft palate only is congenital birth defects where the upper lip and/or palate fail to fuse properly during embryonic facial development. Affecting ~1.2/1000 live births worldwide, these orofacial clefts impose significant social and financial burdens on affected individuals and their families. Orofacial clefts have a complex etiology resulting from genetic variants combined with environmental covariates. Recent genome-wide association studies and whole-exome sequencing for orofacial clefts identified significant genetic associations and variants in several genes. Of these, we investigated the role of common/rare variants in SHH, RORA, MRPL53, ACVR1, and GDF11. MATERIALS AND METHODS: We sequenced these five genes in 1255 multi-ethnic cleft lip with/without palate and cleft palate only samples in order to find variants that may provide potential explanations for the missing heritability of orofacial clefts. Rare and novel variants were further analyzed using in silico predictive tools. RESULTS: Ninteen total variants of interest were found, with variant types including stop-gain, missense, synonymous, intronic, and splice-site variants. Of these, 3 novel missense variants were found, one in SHH, one in RORA, and one in GDF11. CONCLUSION: This study provides evidence that variants in SHH, RORA, MRPL53, ACVR1, and GDF11 may contribute to risk of orofacial clefts in various populations.

[Prokaryotic Expression and Purification of the Notch Ligand and Its Effect on Hematopoiesis after Carbon Tetrachloride Damage].

OBJECTIVE: To express and purify the mouse endothelial cell-targeted recombinant Notch ligand protein mD1R, and to investigate its effect on hematopoiesis after carbon tetrachloride damage. METHODS: PCR was performed to clone and construct the expression vector pET22b(+)-mD1R. The mD1R successfully transformed into E. coli was induced by IPTG, and purified with Ni2+-beads affinity chromatography. The target protein was detected by SDS-PAGE. The fluorescence-activated cell sorting analysis (FACS), cell adhesion test, immunofluorescence staining and quantitative real-time PCR were employed to detect the endothelial cell-targeted and Notch signaling-activated biological characteristics of mD1R. The carbon tetrachloride mouse model was established to observe the effects of mD1R on the hematopoietic stem cell (HSC), myeloid cells and lymphoid cells by flow cytometry. The Lin-Scal-1+c-Kit+ cells were sorted by magnetic bead, FACS was performed to analyze the cell cycle, and RT-PCR was employed to observe the expression of interleukin (IL)-10. RESULTS: The prokaryotic expression vector was successfully cloned and constructed. The purity and the activity were confirmed in mD1R recombinant protein. The purified mD1R activated the Notch signaling pathway of hematopoietic stem cells in carbon tetrachloride damaged mouse, and internally elevated the number of HSC and long-term HSC to 2.96-fold and 6.18-fold. In addition, mD1R improved the amplification of the myeloid progenitor cells and the myeloid-derived suppressor cells, particularly the granulocyte/monocyte into blood. Mechanistically, the further analyses suggested that Notch pathway could increase the proliferation of HSC and enhance expression of IL-10 after stress injury. CONCLUSIONS: A new and activated recombinant Notch ligand protein has been obtained successfully to communicate hematopoietic stem cells and hematopoietic microenvironment. The Notch- mediated intrinsic hematopoiesis has been regulated by the anti-inflammatory factor after stress injury.

[Correlation between Plasma microRNA Expression and Acute Graft-Versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To investigate the microRNA (miRNA) expression in plasma of patients with aGVHD and without aGVHD after allo-hematopoietic stem cell transplantation (allo-HSCT). METHODS: The miRNAs (miR-423, mirR199a-3p, miR93*, miR377) expression levels in peripheral blood plasma of 25 patients before and after allo-HSCT were detected by real-time PCR. RESULTS: miR-423, miR199a-3p and miR-93* in aGVHD group were significantly upregulated (P<0.05); miR-377 expression was not significantly different between aGVHD and non-aGVHD (P>0.05). CONCLUSION: The expression of miR-423, miR-199a-3p, miR-93* are upregulated in aGVHD group, which can be used as biomarkes to monitor and to diagnose aGVHD.

Disruption of Notch signaling aggravates irradiation-induced bone marrow injury, which is ameliorated by a soluble Dll1 ligand through Csf2rb2 upregulation.

Physical and chemical insult-induced bone marrow (BM) damage often leads to lethality resulting from the depletion of hematopoietic stem and progenitor cells (HSPCs) and/or a deteriorated BM stroma. Notch signaling plays an important role in hematopoiesis, but whether it is involved in BM damage remains unclear. In this study, we found that conditional disruption of RBP-J, the transcription factor of canonical Notch signaling, increased irradiation sensitivity in mice. Activation of Notch signaling with the endothelial cell (EC)-targeted soluble Dll1 Notch ligand mD1R promoted BM recovery after irradiation. mD1R treatment resulted in a significant increase in myeloid progenitors and monocytes in the BM, spleen and peripheral blood after irradiation. mD1R also enhanced hematopoiesis in mice treated with cyclophosphamide, a chemotherapeutic drug that induces BM suppression. Mechanistically, mD1R increased the proliferation and reduced the apoptosis of myeloid cells in the BM after irradiation. The ß chain cytokine receptor Csf2rb2 was identified as a downstream molecule of Notch signaling in hematopoietic cells. mD1R improved hematopoietic recovery through up-regulation of the hematopoietic expression of Csf2rb2. Our findings reveal the role of Notch signaling in irradiation- and drug-induced BM suppression and establish a new potential therapy of BM- and myelo-suppression induced by radiotherapy and chemotherapy.

[Construction and expression of fusion protein TRX-hJagged1 in E.coli BL21].

This study was purposed to construct prokaryotic expression vector and to investigate the expression of Notch ligand Jagged1 in E.coli. An expression vector pET-hJagged1 was constructed, which can be inserted in Jagged1 with different lengths, but the DSL domain of human Jagged1 should be contained. Then the recombinant plasmids were transformed into the competent cell of E.coli BL21, and the expression of the fusion protein was induced by IPTG. Fusion protein was purified from the supernatant of cell lysates via the Nickel affinity chromatography. The results showed that prokaryotic expression vectors pET-hJagged1 (Bgl II), pET-hJagged1 (Hind I) and pET-hJagged1 (Stu I) were successfully constructed, but only pET-hJagged1 (Stu I) could express the soluble TRX-hJagged1. The purified TRX-Jagged1 protein could be obtained via the Nickel affinity chromatography, and then confirmed by Western Blot. It is concluded that prokaryotic expression vector pET-hJagged1 is successfully constructed, but only pET-hJagged1 (Stu I) can express the soluble TRX-hJagged1 and the TRX-Jagged1 fusion protein is obtained through the prokaryotic expression system, which laid a solid foundation for further to explore the effects of Jagged1 in hematopoietic and lymphoid system.

FHL1C induces apoptosis in Notch1-dependent T-ALL cells through an interaction with RBP-J.

BACKGROUND: Aberrantly activated Notch signaling has been found in more than 50% of patients with T-cell acute lymphoblastic leukemia (T-ALL). Current strategies that employ γ-secretase inhibitors (GSIs) to target Notch activation have not been successful. Many limitations, such as non-Notch specificity, dose-limiting gastrointestinal toxicity and GSI resistance, have prompted an urgent need for more effective Notch signaling inhibitors for T-ALL treatment. Human four-and-a-half LIM domain protein 1C (FHL1C) (KyoT2 in mice) has been demonstrated to suppress Notch activation in vitro, suggesting that FHL1C may be new candidate target in T-ALL therapy. However, the role of FHL1C in T-ALL cells remained unclear. METHODS: Using RT-PCR, we amplified full-length human FHL1C, and constructed full-length and various truncated forms of FHL1C. Using cell transfection, flow cytometry, transmission electron microscope, real-time RT-PCR, and Western blotting, we found that overexpression of FHL1C induced apoptosis of Jurkat cells. By using a reporter assay and Annexin-V staining, the minimal functional sequence of FHL1C inhibiting RBP-J-mediated Notch transactivation and inducing cell apoptosis was identified. Using real-time PCR and Western blotting, we explored the possible molecular mechanism of FHL1C-induced apoptosis. All data were statistically analyzed with the SPSS version 12.0 software. RESULTS: In Jurkat cells derived from a Notch1-associated T-ALL cell line insensitive to GSI treatment, we observed that overexpression of FHL1C, which is down-regulated in T-ALL patients, strongly induced apoptosis. Furthermore, we verified that FHL1C-induced apoptosis depended on the RBP-J-binding motif at the C-terminus of FHL1C. Using various truncated forms of FHL1C, we found that the RBP-J-binding motif of FHL1C had almost the same effect as full-length FHL1C on the induction of apoptosis, suggesting that the minimal functional sequence in the RBP-J-binding motif of FHL1C might be a new drug candidate for T-ALL treatment. We also explored the molecular mechanism of FHL1C overexpression-induced apoptosis, which suppressed downstream target genes such as Hes1 and c-Myc and key signaling pathways such as PI3K/AKT and NF-κB of Notch signaling involved in T-ALL progression. CONCLUSIONS: Our study has revealed that FHL1C overexpression induces Jurkat cell apoptosis. This finding may provide new insights in designing new Notch inhibitors based on FHL1C to treat T-ALL.

Myc induced miR-144/451 contributes to the acquired imatinib resistance in chronic myelogenous leukemia cell K562.

Imatinib resistance remains the big hurdle for CML therapy. Previous study reveals that c-myc is important for bcr-abl CML cell proliferation, while its role in imatinib resistance is largely unknown. In this study, we first found that c-myc expression is upregulated in imatinib resistant K562R cells, which in turn enhances the expression of miR-144/451. Knockdown of c-myc or restoration of miR-144/451 in the K562R cells sensitizes K562R cells to imatinib therapy. Our study here reveals an regulatory pathway between myc and miR-144/451 and highlights that targeting either myc or miR-144/451 might be valuable for eliminating the imatinib resistant CML cells.

miR-153 sensitized the K562 cells to As2O3-induced apoptosis.

Relapse remains the biggest hurdle of leukemia therapy, while elucidating the molecular mechanism holds promise for the solution. Recently, microRNAs are emerging as an important regulator of cell function. In this study, we for the first time found that miR-153 was downregulated in As2O3-induced drug-resistant K562 cells. In the CD34+ K562 subpopulation, which is characteristic of leukemia stem cell and resembles the drug-resistant subgroup, miR-153 expression level was also much lower than that in the bulk. Forced expression of miR-153 only in K562 cells has no significant effects on cell growth and apoptosis. However, when cells were additionally treated with As2O3, significant greater apoptosis was observed in the miR-153 overexpressed group. Our data here suggest that strategies increasing the endogenous miR-153 might hold promise for an alternative adjuvant therapy of leukemia.

[Clinical analysis of peripheral blood stem cell mobilization regimens in autologous transplantation for treating non-Hodgkin's lymphoma].

The purpose of this study was to compare the efficacy of CEP plus G-CSF and CVP plus G-CSF regimens in the mobilization and collection of peripheral blood hematopoietic stem cells (PBHSC), and in the hematopoietic recovery. 57 patients with non-Hodgkin's lymphoma (NHL) underwent autologous PBHSC transplantation were analyzed retrospectively. The PBHSC were mobilized and collected by using CEP plus G-CSF and CVP plus G-CSF respectively, and were retransfused into these NHL patients after preconditioning, then the mobilization efficacy, adverse reactions and hematopoietic recovery were analyzed. The results showed that the WBC count decreased to ≤ 1.0 × 10(9)/L, platelet amount dropped to ≤ 40 × 10(9)/L during peripheral blood stem cell mobilization of all patients, which indicated successful collection of PBHSC. The mean value of (4.38 ± 3.40) × 10(8)/kg mononuclear cells (MNC) containing (2.79 ± 2.53) × 10(6)/kg CD34(+) cells were collected in CEP plus G-CSF group, while the mean value of (3.31 ± 1.23) × 10(8)/kg MNC containing (2.02 ± 0.87) × 10(6)/kg CD34(+) cells were collected in CVP plus G-CSF group. The efficacy of mobilization in CEP plus G-CSF group was significantly higher than that in CVP plus G-CSF group (p < 0.05). After preconditioning, bone marrow was suppressed in all patients. The average time of WBC count recovery to ≥ 1.0 × 10(9)/L was 11.4 days in CEP plus G-CSF group and 12.3 days in CVP plus G-CSF group; the average time of platelet amount recovery to ≥ 50 × 10(9)/L was 18.6 days in CEP plus G-CSF group and 19.3 days in CVP plus G-CSF group. The statistical analysis showed no significant difference in the average time of hematopoietic recovery between 2 groups. It is concluded that autologous PBHSC transplantation shows significant effect for treatment of patients with NHL. Either modified CEP or CVP plus G-CSF regimen is safe and effective in PBHSC mobilization. The CEP plus G-CSF regimen is better than CVP plus G-CSF regimen.

Knockdown of SOD1 sensitizes the CD34+ CML cells to imatinib therapy.

Leukemia stem cell is thought to be one of the leading causes of imatinib resistance and the resultant relapse of chronic myelogenous leukemia (CML). Eradicating the leukemia stem cells holds the promise of CML treatment. In this study, we found that the CD34+ subpopulation in the CML cell line K562 had a higher expression of SOD1 than that in the CD34 negative cells. Knockdown of SOD1 in CD34+ cells had no significant effects on cell survival and growth, while it sensitized the CD34+ cells to imatinib therapy. N-acetyl-L cysteine (NAC) blocked the pro-apoptotic effects of SOD1 knockdown, suggesting the antioxidant effects of SOD1 was essential for the resistance of CD34+ cells to imatinib therapy. In summary, our results suggest that antagonizing the enhanced endogenous antioxidant activity in leukemia stem cells sheds lights on CML therapy.

Notch signaling maintains proliferation and survival of the HL60 human promyelocytic leukemia cell line and promotes the phosphorylation of the Rb protein.

The Notch signaling pathway has been implicated in the development of several leukemia and lymphoma. In order to investigate the relationship between Notch signaling and acute myeloid leukemia (AML), in this study, we expressed a recombinant Notch ligand protein, the DSL domain of the human Jagged1 fused with GST (GST-Jag1). GST-Jag1 could activate Notch signaling in the human promyelocytic leukemia cell line HL60, as shown by a reporter assay and the induced expression of Notch effector gene Hes1 and Hes5. However, GST-Jag1 had no effect on the proliferation and survival of HL60 cells. HL60 cells expressed both Notch ligands and receptors, and had a potential of reciprocal stimulation of Notch signaling between cells. We, therefore, blocked Notch signaling in cultured HL60 cells using a gamma-secretase inhibitor (GSI). We found that GSI inhibited the proliferation of HL60 cells significantly by blocking the cell-cycle progression in the G1 phase. Furthermore, GSI induced remarkably apoptosis of HL60 cells. These changes in GSI-treated HL60 cells correlated with the down-regulation of c-Myc and Bcl2, and the low phosphorylation of the Rb protein. These results suggested that reciprocal Notch signaling might be necessary for the proliferation and survival of AML cells, possibly through the maintenance of the expression of c-Myc and Bcl2, as well as the phosphorylation of the Rb protein.

Notch and BCR signaling synergistically promote the proliferation of Raji B-lymphoma cells.

The evolutionarily conserved Notch signaling pathway plays a pivotal role in cell proliferation, apoptosis, and cell fate decision from invertebrates to vertebrates, and is oncogenic in some human hematopoietic malignancies. To study the role of Notch signaling in B-lymphoma, we expressed a soluble fragment of human Delta-like1 (hDll1) in E. coli, which was shown to activate the Notch signaling. Incubation of Burkitt's lymphoma Raji cells with the soluble hDll1 led to gamma-secretase-dependent up-regulation of a Notch downstream gene, Hes1. This treatment synergized with B-cell receptor (BCR)-mediated signaling to promote proliferation of Raji cells in vitro, which was cancelled by GSI. We further showed that Notch signaling significantly repressed, while gamma-secretase inhibitor (GSI) enhanced, "natural" apoptosis of Raji cells. Because c-myc is a downstream gene of both Notch signaling and BCR signaling, and GSI blocked c-myc expression in the presence of hDll1 and anti-IgM, Notch signaling might interact with BCR signaling at the level of c-myc expression to regulate proliferation and apoptosis of B-lymphoma cells.

[Research advance of notch signal in ex vivo expansion of hematopoietic progenitor cells - review].

Ex vivo expansion of hematopoietic progenitor cells (HPCs) is valuable for clinical application, however, traditional ex vivo culture negatively affects long-term hematopoietic reconstitution ability. In the hematopoietic system, the expression of Notch receptors and their ligands has been widely reported. Active Notch signal inhibits the differentiation of HSCs while promotes their expansion, suggesting that ex vivo expansion of hematopoietic progenitor cells could be enhanced by manipulating Notch signal pathways. In this article the Notch signal pathways, Notch signal and maintenance of hematopoietic progenitor cells, Notch signal and expansion of hematopoietic progenitor cells and molecular mechanism of Notch signal maintaining undifferentiation of hematopoietic progenitor cells were reviewed.

[Construction and expression of a fusion protein containing extracellular domain of human Jagged1 and Fc fragment of human IgG1 in Pichia Pastoris].

In order to construct a pichia pastoris expression vector containing the extracellular domain of human Jagged1 and the Fc fragment of human IgG1 fusion gene, or containing only the Fc fragment of human IgG1 and to express them in pichia pastoris. The extracellular domain of human Jagged1 gene was cloned from normal human bone marrow cells. After DNA sequencing, the extracellular domain of Jagged1 gene was inserted into pIC-Fc vector constructed previously, which is Pichia pastoris expression vector containing only the Fc fragment of human IgG1. The constructed plasmid was transformed into yeast GS115 by means of electroporation. The recombinant transformants with a high copy number of the plasmid were selected on MD plate with G418. The expression of protein was induced by addition of methanol. Then, protein expression was analyzed by SDS-PAGE. The results indicated that the extracellular domain of human Jagged1 gene was effectively amplified. The DNA sequencing result showed that the constructed plasmid containing hJagged1(ext)-Fc fusion gene was the same as designed. The fusion protein was successfully expressed in Pichia pastoris. It is concluded that the hJagged1(ext) gene has been successfully cloned and expressed, which provides a new fusion protein for further experiments, the hJagged1(ext)-Fc fusion protein can be used as a new stimulator for proliferation of hematopoietic stem/progenitor cells in vitro.

[Construction and expression of a fusion protein containing extracellular domain of human Delta-like1 and Fc fragment of human IgG1 in the Pichia pastoris].

AIM: To construct a Pichia pastoris expression vector PIC- hDll1(ext)-Fc, and to express the fusion protein containing the extracellular domain of human Delta-like1 and the Fc fragment of human IgG1 fusion gene in Pichia pastoris. METHODS: The extracellular domain of human Delta-like1 gene was amplified from pEF-BOSneo-hdll1(ext)-Fc by PCR. The expression vector was constructed by DNA recombination. The constructed plasmid was transformed into yeast GS115 by electroporation. The recombinant transformants with a high copy number of the plasmid were selected by using MD plate and G418. The expression of protein was induced by addition of methanol.Then analyzed protein expression by SDS-PAGE and Western blot. RESULTS: The extracellular domain of human Delta-like1 gene was effectively amplified. The DNA sequencing result showed that the constructed plasmid containing hDll(ext)-Fc fusion gene was the same as designed. The fusion protein was successfully expressed in Pichia pastoris. CONCLUSION: The hDll1(ext) gene has been successfully cloned and expressed in the form of Fc fusion protein, which provides a new fusion protein for further experiments.