High-yield expression of recombinant mouse coagulation factor Ⅶ in methylotrophic yeast Pichia pastoris

Objective: To explore high-yield secretory expression of recombinant mouse coagulation factor Ⅶ (rmF Ⅶ ) protein in Pichia pastoris (P. pastoris). Methods: The fragment of mF Ⅶ cDNA was amplified by PCR from a pcDNA3-mFⅦ plasmid. Then the cDNA fragment was subcloned into α-factor secretion signal open reading frame of pPIC9K secretory expression vector. The mutagenesis of mF Ⅶ was performed by Site-Direct Mutation and then verified by DNA sequencing. The yeast expression vector of rmF Ⅶ, named as pPIC9K-rmFⅦ, was linearized with Sac I and transferred into GS115 strains(his-Mut+)by electroporation. The recombinants were identified by direct PCR and selection on MM and MD plates. rmF Ⅶ was expressed in recombinant strains (his+Mut+) for 4 d. The expression level and activation of rmF Ⅶ in the BMMY medium were detected by SDS-PAGE and Western blot respectively. Results:pPIC9K-rmFⅦ was constructed and transferred to GS115 strains successfully. 48-hour post induction by methanol rmFⅦ protein was secreted into the culture supernatant. The molecular weight of the expressed products was shown to be about 46 kD by SDS-PAGE analysis. Western blot showed that the expressed rmF Ⅶ exhibited specificity and antigenicity. Conclusion: Since mFⅦ is considered as a tumor-targeting molecule , this study may provide a basis for further anti-tumor strategy on rmFⅦ.

Experimental study on MyoD gene induced differentiation of bone marrow mesen-chymal stem cells into myoblasts in vitro

Objective: To explore the possibility of the transfection of MyoD gene induced bone marrow mesenchymal stem cells ( MSCs) to differentiate into myoblasts in vitro. Methods: The eukaryotic expression plasmid vector pIRES2-EGFP-MyoD was transfected into MSCs with lipotransfection method, and the positive cells were selected by G418; The expression of MyoD was detected in the transfected MSCs with RT-PCR and the amplified, purified product was identified by sequencing; The reporter gene enhanced green fluorescence protein ( EFGP) was observed in the transfected cells under a fluorescent and a laser confocal microscopes; Immunohistochemical methods was used to examine the expressions of MyoD, myogenin, myosin, myoglobin and desmin in the differentiated cells. The ultrastructure changes of the cells before and after transfection were observed with electron microscopy. Results: The expression of MyoD was detected in the transfected MSCs with RT-PCR and the amplified, purified product was as same in sequence as that from Genbank; Green fluorescence was observed in the transfected cells under a fluorescent and a laser confocal microscopes; Immunohistochemical methods indicated that MyoD, myogenin, myosin, myoglobin and desmin were expressed in the transfected cells; The transfected cells showed the morphological characteristics of mature cells with filaments in their cytoplasm. Conclusion: MyoD gene can induce cultured MSCs to successfully differentiate into myoblasts , probably providing an experimental foundation for trauma repair.

RNF219 interacts with CCR4-NOT in regulating stem cell differentiation

Regulation of RNA stability plays a crucial role in gene expression control.Deadenylation is the initial rate-limiting step for the majority of RNA decay events.Here,we show that RING finger protein 219(RNF219)interacts with the CCR4-NOT deadenylase complex.RNF219-CCR4-NOT exhibits deadenylation activity in vitro.RNA-seq analyses identify some of the 2-cell-specific genes and the neuronal genes significantly downregulated upon RNF219 knockdown,while upregulated after depletion of the CCR4-NOT subunit CNOTIO in mouse embryonic stem(ES)cells.RNF219 depletion leads to impaired neuronal lineage commitment during ES cell differentiation.Our study suggests that RNF219 is a novel interacting partner of CCR4-NOT and required for maintenance of ES cell pluripotency.