Development and characterization of polyclonal antibodies against the linker region of the telomere-binding protein TRF2

Background: TRF2 (telomeric repeat binding factor 2) is an essential component of the telomere-binding protein complex shelterin. TRF2 induces the formation of a special structure of telomeric DNA and counteracts activation of DNA damage-response pathways telomeres. TRF2 has a poorly characterized linker region (udTRF2) between its homodimerization and DNA-binding domains. Some lines of evidence have shown that this region could be involved in TRF2 interaction with nuclear lamina. Results: In this study, the fragment of the TERF2 gene encoding udTRF2 domain of telomere-binding protein TRF2 was produced by PCR and cloned into the pET32a vector. The resulting plasmid pET32a-udTRF2 was used for the expression of the recombinant udTRF2 in E. coli RosettaBlue (DE3). The protein was isolated and purified using ammonium sulfate precipitation followed by ion-exchange chromatography. The purified recombinant protein udTRF2 was injected into guinea pigs to generate polyclonal antibodies. The ability of anti-udTRF2 antibodies to bind endogenous TRF2 in human skin fibroblasts was tested by western blotting and immunofluorescent staining. Conclusions: In this study, the recombinant protein udTRF2 and antibodies to it were generated. Both protein and antibodies will provide a useful tool for investigation of the functions of the udTRF2 domain and its role in the interaction between TRF2 and nuclear lamina.

Vitamin C alleviates aging defects in a stem cell model for Werner syndrome

Werner syndrome (WS) is a premature aging disorder that mainly affects tissues derived from mesoderm. We have recently developed a novel human WS model using WRN-deficient human mesenchymal stem cells (MSCs). This model recapitulates many phenotypic features of WS. Based on a screen of a number of chemicals, here we found that Vitamin C exerts most efficient rescue for many features in premature aging as shown in WRN-deficient MSCs, including cell growth arrest, increased reactive oxygen species levels, telomere attrition, excessive secretion of inflammatory factors, as well as disorganization of nuclear lamina and heterochromatin. Moreover, Vitamin C restores in vivo viability of MSCs in a mouse model. RNA sequencing analysis indicates that Vitamin C alters the expression of a series of genes involved in chromatin condensation, cell cycle regulation, DNA replication, and DNA damage repair pathways in WRN-deficient MSCs. Our results identify Vitamin C as a rejuvenating factor for WS MSCs, which holds the potential of being applied as a novel type of treatment of WS.

Prevalencia de anticuerpos anti envoltura nuclear y sus isotipos en sueros positivos para anticuerpos antinucleares / Prevalence of antinuclear envelope antibodies and their isotypes in sera positive for antinuclear antibodies

Antinuclear antibodies detected in HEp-2 cells by indirect immunofluorescence assay display a great variety of images, including the nuclear envelope pattern. This is quite a less frequent finding. Two thousand five hundred and ninety-four sera were processed, and 37.6% of ANA were detected. The prevalence of anti-nuclear envelope antibodies (ANEA) was of 1.2%, with a high association with autoimmune liver diseases (83%) and a low association with systemic lupus erythematosus. In 21 sera of patients with ANEA, no anti-DNAn antibodies were found; but 28.6% of anti-smooth muscle antibodies and 19% of anti-mitochondrial antibodies were detected. The triple rodent tissue section proved to be a less sensitive substrate than HEp-2 for the detection of ANEA. When using conjugates against different isotypes of antibodies for the detection of ANA, 90.5% of IgG, 66.6% of IgA and 9.5% of IgM. Two patients had ANEA-IgA at high titers (> or = 1:160) without ANEA-IgG. In this work, the importance of performing complementary tests for the detection of anti-smooth muscle antibodies, anti-mitochondrial antibodies and anti-DNAn is highlighted in order to apply these tests as guidelines for the clinical diagnosis of patients with ANEA. Besides, this study expresses the need of using total anti-Ig antibodies as conjugate for IIF-HEp-2 instead of anti-lgG; until the role of IgA antibodies in these autoimmune diseases is clarified.