Anti-RPL26 monoclonal antibody Made to order

Cellular responses to DNA damage are critical determinants of cancer development and aging-associated pathogenesis. Here, we identify and characterize a DNA-damage response (DDR) pathway that regulates alternative splicing of numerous gene products, including the human tumor suppressor TP53, and controls DNA damage-induced cellular senescence. In brief, ionizing radiation (IR) inhibits the activity of SMG1, a phosphoinositide-3-kinase-like kinase family member, reducing the binding of SMG1 to a specific region near exon 9 of p53 precursor mRNA and promoting the binding of ribosomal protein L26 (RPL26) to p53 pre-mRNA. RPL26, in turn, is required for the recruitment of the serine/arginine-rich splicing factor SRSF7 to p53 pre-mRNA and generation of alternatively spliced p53 beta RNA. Disruption of this pathway via selective knockout of p53 beta by CRISPR/Cas9 or downregulation of pathway constituents significantly reduces IR-induced senescence markers, and cells lacking p53 beta expression fail to transcriptionally repress negative regulators of cellular senescence and aging. SIGNIFICANCE: We identified a new component of the DDR pathway that regulates alternative splicing of messenger RNAs, including human TP53 mRNA. Modulation of this regulatory pathway affects DNA-damage induction of cellular senescence markers. (C) 2017 AACR.

DNA methylation is a vital component of the epigenetic machinery that orchestrates changes in multiple genes and helps regulate gene expression in all known vertebrates. We evaluated immunoreactivity for two markers of DNA methylation and eight methylation maintenance factors in entorhinal cortex layer II, a region exhibiting substantial Alzheimer's disease (AD) pathology in which expression changes have been reported for a wide variety of genes. We show, for the first time, neuronal immunoreactivity for all 10 of the epigenetic markers and factors, with highly significant decrements in AD cases. These decrements were particularly marked in PHF1/PS396 immunoreactive, neurofibrillary tangle-bearing neurons. In addition, two of the DNA methylation maintenance factors, DNMT1 and MBD2, have been reported also to interact with ribosomal RNAs and ribosome synthesis. Consistent with these findings, DNMT1 and MBD2, as well as p66 alpha, exhibited punctate cytoplasmic immunoreactivity that co-localized with the ribosome markers RPL26 and 5.8 s rRNA in ND neurons. By contrast, AD neurons generally lacked such staining, and there was a qualitative decrease in RPL26 and 5.8 s rRNA immunoreactivity. Collectively, these findings suggest epigenetic dysfunction in AD-vulnerable neurons. (C) 2008 Elsevier Inc. All rights reserved.