EXPRESSION OF c－myc GENE AND BIOSYNTHESIS OF BIOLOGICAL MACROMOLECULES IN ANTISENSE TRANSFECTANT HL_（60）~R－9

The recombinant plasmid PGC was constructed for transcription unit of c-myc gene with diorientation in vitro, to make RNA probes for detection of c-myc mRNA and antisence RNA expression of tranfectant HL-9,which was obtained from HL60 cells transfected with inducible c-myc antisense RNA expression plasmid. The results from HL-9 cells induced by Cd2+ indicated that expression of c-myc antisense RNA increased with Cd2+ concentration and exposure time, while c-myc mRNA expression progressively reduced. Using immunohistochemical technique no c-myc P62 protein expression was detected. The incorporation of 3H-TdR, 3H-UR and 3H-Leu revealed significant suppression of DNA, RNA and protein biosynthesis. It is suggested that the reversion changes previously reported in malignant Phenotypes of HL-9 cells and the inhibition of macromolecular biosynthesis mentioned above were associated with the blockade of c-myc gene expression by its antisense RNA.

Phosphorus deficiency affects multiple macromolecular biosynthesis pathways of Thalassiosira weissflogii

Phosphorus（P） is one of the key nutrients for the growth of phytoplankton. In this study, we used a method coupling label-free quantitation with liquid chromatography–mass spectrometry（LFQ–LC–MS/MS） to track the change of relative protein abundance between P-replete and P-deficient treatments in a non-model diatom, Thalassiosira weissflogii. Out of the 631 proteins identified, 132 were found to have significant changes in abundance（〉1.5 folds） between the two treatments, especially those proteins involved in macromolecular biosynthesis pathways. For example, the up-regulation of sulfolipid biosynthesis protein in the P-deficient culture suggested a switch from using phospholipids to sulfolipids. In addition, the ribosome subunits and tRNA synthetases were down-regulated, which might explain the decrease in protein content in the P-deficient culture. A vacuolar sorting receptor homologous protein was found to be 9.2-folds up-regulated under P-deficiency, indicating an enhancement in the vacuolar sorting pathway for protein degradation. Our results show that T. weissflogii has sophisticated responses in multiple macromolecular metabolism pathways under P-deficiency, a mechanism which can be critical for this species to survive under various levels of P availability in the environment

Construction of a plasmid for human brain-derived neurotrophic factor and its effect on retinal pigment epithelial cell viability

Several studies have investigated the protective functions of brain-derived neurotrophic factor（BDNF） in retinitis pigmentosa. However, a BDNF-based therapy for retinitis pigmentosa is not yet available. To develop an efficient treatment for fundus disease, an eukaryotic expression plasmid was generated and used to transfect human 293 T cells to assess the expression and bioactivity of BDNF on acute retinal pigment epithelial-19（ARPE-19） cells, a human retinal epithelial cell line. After 96 hours of co-culture in a Transwell chamber, ARPE-19 cells exposed to BDNF secreted by 293 T cells were more viable than ARPE-19 cells not exposed to secreted BDNF. Western blot assay showed that Bax levels were downregulated and that Bcl-2 levels were upregulated in human ARPE-19 cells exposed to BDNF. Furthermore, 293 T cells transfected with the BDNF gene steadily secreted the protein. The powerful anti-apoptotic function of this BDNF may be useful for the treatment of retinitis pigmentosa and other retinal degenerative diseases.

A cascade of redox reactions in the biosynthesis of the protein phosphatase-2A inhibitor rubratoxin A

Subject Code:H30 With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Hu Youcai(胡友财),Prof.Yu Shishan(庾石山)and Prof.Tang Yi(唐奕)from the State Key Laboratory of Bioactive Substance and Function of Natural Medicines,Institute

Distinct pathogenic mechanisms of various RARS1 mutations in Pelizaeus-Merzbacher-like disease

Mutations of the genes encoding aminoacyl-tRNA synthetases are highly associated with various central nervous system disorders.Recurrent mutations,including c.5A>G,p.D2G;c.1367C>T,p.S456L;c.1535G>A,p.R512Q and c.1846_1847del,p.Y616Lfs*6 of RARS1 gene,which encodes two forms of human cytoplasmic arginyl-tRNA synthetase(hArgRS),are linked to Pelizaeus-Merzbacher-like disease(PMLD)with unclear pathogenesis.Among these mutations,c.5A>G is the most extensively reported mutation,leading to a p.D2G mutation in the N-terminal extension of the long-form hArgRS.Here,we showed the detrimental effects of R512Q substitution andΔC mutations on the structure and function of hArgRS,while the most frequent mutation c.5A>G,p.D2G acted in a different manner without impairing hArgRS activity.The nucleotide substitution c.5A>G reduced translation of hArgRS mRNA,and an upstream open reading frame contributed to the suppressed translation of the downstream main ORF.Taken together,our results elucidated distinct pathogenic mechanisms of various RARS1 mutations in PMLD.