OsPIE1, the Rice Ortholog of Arabidopsis PHOTOPERIOD-INDEPENDENT EARLY FLOWERING1, Is Essential for Embryo Development

orthologs in monocots remains unknown., respectively).Taken together, our results suggest that OsPIE1 is the rice ortholog of Arabidopsis PIE1 and plays an essential role in rice embryo development

SUMO modification of PCNA is controlled by DNA

Post-translational modification by the ubiquitin-like protein SUMO is often regulated by cellular signals that restrict the modification to appropriate situations. Nevertheless, many SUMO-specific ligases do not exhibit much target specificity, and—compared with the diversity of sumoylation substrates—their number is limited. This raises the question of how SUMO conjugation is controlled in vivo. We report here an unexpected mechanism by which sumoylation of the replication clamp protein, PCNA, from budding yeast is effectively coupled to S phase. We find that loading of PCNA onto DNA is a prerequisite for sumoylation in vivo and greatly stimulates modification in vitro. To our surprise, however, DNA binding by the ligase Siz1, responsible for PCNA sumoylation, is not strictly required. Instead, the stimulatory effect of DNA on conjugation is mainly attributable to DNA binding of PCNA itself. These findings imply a change in the properties of PCNA upon loading that enhances its capacity to be sumoylated

Genetic and Physical Interactions between Tel2 and the Med15 Mediator Subunit in Saccharomyces cerevisiae

International audienceBACKGROUND: In budding yeast, the highly conserved Tel2 protein is part of several complexes and its main function is now believed to be in the biogenesis of phosphatidyl inositol 3-kinase related kinases. PRINCIPAL FINDINGS: To uncover potentially novel functions of Tel2, we set out to isolate temperature-sensitive (ts) mutant alleles of TEL2 in order to perform genetic screenings. MED15/GAL11, a subunit of Mediator, a general regulator of transcription, was isolated as a suppressor of these mutants. The isolated tel2 mutants exhibited a short telomere phenotype that was partially rescued by MED15/GAL11 overexpression. The tel2-15 mutant was markedly deficient in the transcription of EST2, coding for the catalytic subunit of telomerase, potentially explaining the short telomere phenotype of this mutant. In parallel, a two-hybrid screen identified an association between Tel2 and Rvb2, a highly conserved member of the AAA+ family of ATPases further found by in vivo co-immunoprecipitation to be tight and constitutive. Transiently overproduced Tel2 and Med15/Gal11 associated together, suggesting a potential role for Tel2 in transcription. Other Mediator subunits, as well as SUA7/TFIIB, also rescued the tel2-ts mutants. SIGNIFICANCE: Altogether, the present data suggest the existence of a novel role for Tel2, namely in transcription, possibly in cooperation with Rvb2 and involving the existence of physical interactions with the Med15/Gal11 Mediator subunit

Anti-PCNA autoantibodies preferentially recognize C-terminal of PCNA in patients with chronic hepatitis B virus infection

We previously reported anti-PCNA autoantibodies in sera from patients with chronic HBV and HCV infection. To analyse the antigenic regions on proliferating cell nuclear antigen (PCNA) that confer autoantibody binding in patients with chronic hepatitis B (HBV) and C (HCV) infection, eight constructs including one wild type PCNA, one mutant type Y114A_PCNA and six C- or N-terminal PCNA truncations were generated. Sera from 185 patients with systemic lupus erythematosus (SLE), 178 with chronic HBV and 163 with chronic HCV infection, and 68 healthy individuals were examined for the presentation of anti-PCNA antibodies by enzyme linked immunosorbent assay (ELISA). By ELISA, anti-PCNA positive sera from patients with SLE, chronic HBV and HCV infection preferentially recognized the wild type PCNA more than the mutant type Y114A_PCNA (P< 0·05). The inhibition of binding by purified full-length rPCNA proteins with anti-PCNA positive sera was shown to exceed 70%. The inhibition of binding by purified truncated rPCNA proteins with sera from patients with chronic HBV and HCV infection and SLE was shown to confer dominant binding in T(L2) and T(L3). Moreover, the higher frequency of inhibition by using T(L3) was found in patients with chronic HBV infection. These data indicate that anti-PCNA autoantibodies preferentially recognize C-terminal of PCNA in patients with chronic HBV infection and may also provide advanced understanding between viral infection and autoimmunity for further study

Essential interaction between the fission yeast DNA polymerase δ subunit Cdc27 and Pcn1 (PCNA) mediated through a C-terminal p21(Cip1)-like PCNA binding motif

Direct interaction between DNA polymerase δ and its processivity factor proliferating cell nuclear antigen (PCNA) is essential for effective replication of the eukaryotic genome, yet the precise manner by which this occurs is unclear. We show that the 54 kDa subunit of DNA polymerase δ from Schizosaccharomyces pombe interacts directly with Pcn1 (PCNA) both in vivo and in vitro. Binding is effected via a short sequence at the C–terminus of Cdc27 with significant similarity to the canonical PCNA binding motif first identified in the mammalian p21(Cip1) protein. This motif is both necessary and sufficient for binding of Pcn1 by Cdc27 in vitro and is essential for Cdc27 function in vivo. We also show that the Pcn1 binding motif in Cdc27 is distinct from its binding site for Cdc1, the 55 kDa B-subunit of polymerase δ, and present evidence that Cdc27 can bind to Pcn1 and Cdc1 simultaneously. Finally, we show that Cdc27 performs at least two distinct essential functions, one of which is independent of Pcn1 binding

Upregulation of nuclear factor-related kappa B suggests a disorder of transcriptional regulation in minimal change nephrotic syndrome.

Immune mechanisms underlying the pathophysiology of idiopathic nephrotic syndrome, the most frequent glomerular disease in children, are believed to involve a systemic disorder of T cell function and cell mediated immunity. How these perturbations take place remains unclear. We report here that NFRKB, a member of the chromatin remodeling complex, is upregulated in MCNS relapse, mainly in CD4+T cells and B cells and undergo post-translational modifications including sumoylation. We showed that NFRKB was highly expressed in nuclear compartment during the relapse, while it was restricted to cytoplasm in remission. NFRKB induced the activation of AP1 signaling pathway by upregulating the expression of c-jun. We showed that NFRKB promotes hypomethylation of genomic DNA, suggesting its implication in regulation of gene expression by enhancing the binding of transcription factors through chromatin remodeling. These results suggest for the first time that NFRKB may be involved in the disorders of transcriptional regulation commonly observed in MCNS relapse