PDCD5 interacts with p53 and functions as a positive regulator in the p53 pathway

RNA profiles of porcine embryos during genome activation reveal complex metabolic switch sensitive to in vitro conditions

Fertilization is followed by complex changes in cytoplasmic composition and extensive chromatin reprogramming which results in the abundant activation of totipotent embryonic genome at embryonic genome activation (EGA). While chromatin reprogramming has been widely studied in several species, only a handful of reports characterize changing transcriptome profiles and resulting metabolic changes in cleavage stage embryos. The aims of the current study were to investigate RNA profiles of in vivo developed (ivv) and in vitro produced (ivt) porcine embryos before (2-cell stage) and after (late 4-cell stage) EGA and determine major metabolic changes that regulate totipotency. The period before EGA was dominated by transcripts responsible for cell cycle regulation, mitosis, RNA translation and processing (including ribosomal machinery), protein catabolism, and chromatin remodelling. Following EGA an increase in the abundance of transcripts involved in transcription, translation, DNA metabolism, histone and chromatin modification, as well as protein catabolism was detected. The further analysis of members of overlapping GO terms revealed that despite that comparable cellular processes are taking place before and after EGA (RNA splicing, protein catabolism), different metabolic pathways are involved. This strongly suggests that a complex metabolic switch accompanies EGA. In vitro conditions significantly altered RNA profiles before EGA, and the character of these changes indicates that they originate from oocyte and are imposed either before oocyte aspiration or during in vitro maturation. IVT embryos have altered content of apoptotic factors, cell cycle regulation factors and spindle components, and transcription factors, which all may contribute to reduced developmental competence of embryos produced in vitro. Overall, our data are in good accordance with previously published, genome-wide profiling data in other species. Moreover, comparison with mouse and human embryos showed striking overlap in functional annotation of transcripts during the EGA, suggesting conserved basic mechanisms regulating establishment of totipotency in mammalian development.

Plasma and synovial fluid programmed cell death 5 (PDCD5) levels are inversely associated with TNF-α and disease activity in patients with rheumatoid arthritis

CONTEXT

Programmed cell death 5 (PDCD5), a novel apoptotic regulatory gene, has been reported to be associated with rheumatoid arthritis (RA) and osteoarthritis (OA), which can regulate the apoptosis of synoviocytes and chondrocytes cultured in vitro.

OBJECTIVE

To study expression characteristic of PDCD5 in plasma and synovial fluid of RA patients, and analyze its correlation with tumor necrosis factor alpha (TNF-α) and disease activity in RA.

METHODS

A total of 135 subjects were recruited into this study (44 RA patients, 46 OA patients and 45 healthy controls). PDCD5 and TNF-α concentrations in plasma and synovial fluid were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Plasma and synovial fluid PDCD5 concentrations were significantly elevated in RA patients. Pearson correlation analysis indicated that plasma and synovial fluid PDCD5 levels were inversely correlated with TNF-α. Moreover, plasma PDCD5 levels were also inversely correlated with C-reactive protein and erythrocyte sedimentation rate.

CONCLUSION

Plasma and synovial fluid PDCD5 could be useful for monitoring the activity and progression of RA, and its abnormal expression and dysfunction may be correlated to TNF-α in RA patients.

Co-chaperon DnaJC7/TPR2 enhances p53 stability and activity through blocking the complex formation between p53 and MDM2

Tumor suppressor p53 plays a critical role in the regulation of DNA damage response. Upon severe DNA damage, p53 promotes apoptosis to eliminate cells with seriously damaged DNA to maintain genomic integrity. Pro-apoptotic function of p53 is tightly linked to its sequence-specific transactivation ability. In the present study, we have identified co-chaperon DnaJC7/TPR2 as a novel binding partner of p53 by yeast-based two-hybrid screening. In the two-hybrid screening, we used the central DNA-binding domain of p53 as a bait. Co-immunoprecipitation experiments demonstrated that DnaJC7 is associated with p53 in mammalian cells. Luciferase reporter and colony formation assays revealed that DnaJC7 enhances p53-dependent transcriptional as well as growth-suppressive activity. Forced expression of DnaJC7 induced to extend a half-life of p53, indicating that DnaJC7-mediated activation of p53 might be at least in part due to its prolonged half-life. Consistent with these observations, the amount of p53/MDM2 complex was markedly reduced in the presence of DnaJC7, suggesting that DnaJC7 dissociates MDM2 from p53. Taken together, our present findings strongly suggest that DnaJC7 participates in p53/MDM2 negative feedback regulatory pathway, and thereby enhancing the stability and activity of p53.