Characteristic element of matrix attachment region mediates vector attachment and enhances nerve growth factor expression in Chinese hamster ovary cells.

Preliminary studies have suggested that a characteristic element of the matrix attachment region (MAR) in human interferon-ß mediates the adhesion of vectors to Chinese hamster ovary (CHO) cells. In this study, we investigated if vector adhesion increased nerve growth factor (NGF) expression in CHO cells. The MAR characteristic element sequence of human interferon-ß was inserted into the multiple-cloning site of the pEGFP-C1 vector. The target NGF gene was inserted upstream of the MAR characteristic element sequence to construct the MAR/NGF expression vector. The recombinant plasmid was transfected into CHO cells and stable monoclonal cells were selected using G418. NGF mRNA and protein expression was detected by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Plasmid reduction experiments were used to determine the state of transfected plasmid in mammalian cells. The insertion of MAR into the vector increased NGF expression levels in CHO cells (1.93- fold) compared to the control. The recombinant plasmid expressing the MAR sequence was digested into a linear space vector. The inserted MAR and NGF sequences were consistent with those inserted into the plasmid before recombination. Therefore, we concluded that the MAR characteristic element mediates vector adhesion to CHO cells and enhances the stability and efficiency of the target gene expression.

Regulating effects of insertion direction of matrix attachment regions on transgenic expression in stably transformed Chinese hamster ovary cells.

We investigated the effects of different directions of insertion of matrix attachment region (MAR) sequences on transgenic expression in stably transformed Chinese hamster ovary (CHO) cells. The MAR sequences were inserted in forward or reverse directions into the expression vectors, and transfected into CHO cells. The expression of the chloramphenicol acetyltransferase (CAT) reporter gene and the relative copy numbers of the CAT gene were analyzed. The CAT gene expression levels in the vector with the MAR sequence inserted in the forward or reverse directions increased compared with expression without the MAR sequence. The relative copy numbers of the CAT gene with MAR sequenced vectors inserted in the reverse and forward directions were lower, than in the control group. The direction of insertion of MAR sequences had no significant effect on expression levels. The expression levels were not proportional to the copy numbers of the gene.

Association of SIRT2 gene polymorphisms with body measurement and growth traits of Qinchuan cattle.

Silent information regulator 2 (SIRT2), a member of the Sirtuin family of class III nicotinamide adenine dinucleotide-dependent protein deacetylases, plays an important role in senescence, metabolism, and apoptosis. This study was conducted to detect potential polymorphisms of the bovine SIRT2 gene and explore their relationships with meat quality and body measurement traits (BMTs) in Qinchuan cattle. Four single nucleotide polymorphisms (A7445G, C7711T, G17937A, and G20937A) in the fourth intron, fourth exon, ninth exon, and twelfth exon of the SIRT2 gene, respectively, were identified according to the sequencing results of 520 individuals of a Qinchuan cattle population. The genotypic distributions of both A7445G and G20937A were in agreement with the Hardy-Weinberg equilibrium (P < 0.05), whereas the other two mutations were not (0.05 < P < 0.01), based on the X(2) test. Association analysis indicated that the four loci were significantly correlated with several BMTs and meat quality traits. When in combination, the H1H1 (AA-CC-GG-CC) diplotypes showed better BMT and meat quality traits than those by other combinations. Collectively, the results show that SIRT2 is involved in the regulation of the growth and meat quality of cattle, suggesting that the SIRT2 gene may be a candidate gene for marker-assisted selection in the development of future breeding programs for Qinchuan cattle.