The AMPK/PGC-1α metabolic pathway and nuclear respiratory factor 1 up-regulate human telomere transcription.

Human genomic DNA extracted from urine could be an interesting tool for large-scale public health studies involving characterization of genetic variations or DNA biomarkers as a result of the simple and noninvasive collection method. These studies, involving many samples, require a rapid, easy, and standardized extraction protocol. Moreover, for practicability, there is a necessity to collect urine at a moment different from the first void and to store it appropriately until analysis. The present study compared seven commercial kits to select the most appropriate urinary human DNA extraction procedure for epidemiological studies. DNA yield has been determined using different quantification methods: two classical, i.e., NanoDrop and PicoGreen, and two species-specific real-time quantitative (q)PCR assays, as DNA extracted from urine contains, besides human, microbial DNA also, which largely contributes to the total DNA yield. In addition, the kits giving a good yield were also tested for the presence of PCR inhibitors. Further comparisons were performed regarding the sampling time and the storage conditions. Finally, as a proof-of-concept, an important gene related to smoking has been genotyped using the developed tools. We could select one well-performing kit for the human DNA extraction from urine suitable for molecular diagnostic real-time qPCR-based assays targeting genetic variations, applicable to large-scale studies. In addition, successful genotyping was possible using DNA extracted from urine stored at -20°C for several months, and an acceptable yield could also be obtained from urine collected at different moments during the day, which is particularly important for public health studies.

Among all molecules developed for anticancer therapies, photodynamic therapeutic agents have a unique profile. Their maximal activity is specifically triggered in tumors by light and toxicity of even systemically delivered drug is prevented in non-illuminated parts of the body. Photosensitizers exert their therapeutic effect by producing reactive oxygen species via a lightactivated reaction with molecular oxygen. Consequently, the lowering of pO2 deep in solid tumors limits their treatment and makes essential the design of oxygen-independent sensitizers. In this perspective, we have recently developed Ir(III)-based molecules able to oxidize biomolecules by type I processes under free-oxygen conditions. We examine here their photo-toxicity in relevant biological models. We show that drugs, which are mitochondria-accumulated, induce upon light irradiation a dramatic decrease of the cell viability, even under low oxygen conditions. Finally, assays on 3D tumor spheroids highlight the importance of the light-activation step and the oxygen consumption rate on the drug activity.

The design and characterization of new ruthenium(II) complexes aimed at targeting G‐quadruplex DNA is reported. Importantly, these complexes are based on oxidizing 1,4,5,8‐tetraazaphenanthrene (TAP) ancillary ligands known to favour photo‐induced electron transfer (PET) with DNA. The photochemistry of complexes 1–4 has been studied by classical methods, which revealed two of them to be capable of photo‐abstracting an electron from guanine. From studies of the interactions with DNA through luminescence, circular dichroism, bio‐layer interferometry, and surface plasmon resonance experiments, we have demonstrated the selectivity of these complexes for telomeric G‐quadruplex DNA over duplex DNA. Preliminary biological studies of these complexes have been performed: two of them showed remarkable photo‐cytotoxicity towards telomerase‐negative U2OS osteosarcoma cells, whereas very low mortality was observed in the dark at the same photo‐drug concentration.

Highlights d TSPYL5 is a telomere-associated protein crucial for the survival of ALT + cells only d TSPYL5 protects POT1 from poly-ubiquitination and degradation in ALT + cells d TSPYL5-depleted ALT + cells require USP7 deubiquitinase for POT1 poly-ubiquitination d ALT telomere association with PML bodies sensitizes POT1 to poly-ubiquitination

Long noncoding RNAs, produced from distinct regions of the chromosomes, are emerging as new key players in several important biological processes. The long noncoding RNAs add a new layer of complexity to cellular regulatory pathways, from transcription to cellular trafficking or chromatin remodeling. More than 25 years ago, the discovery of a transcriptional activity at telomeres of protozoa ended the long‐lasting belief that telomeres were transcriptionally silent. Since then, progressively accumulating evidences established that production of TElomeric Repeat‐containing RNA (TERRA) was a general feature of eukaryotic cells. Whether TERRA molecules always originate from the telomeres or whether they can be transcribed from internal telomeric repeats as well is however still a matter of debate. Whether TERRA transcripts always localize to telomeres and play similar roles in all eukaryotic cells is also unclear. We review the studies on TERRA localization in the cell, its composition and some aspects of its transcriptional regulation to summarize the current knowledge and controversies about the genomic origin of TERRA, with a focus on human and mouse TERRA.

How to citeABDUL, Fabien et al. Smc5/6 silences episomal transcription by a three-step function. In: Nature structural & molecular biology, 2022.

Lactobacillus plantarum is a lactic acid bacterium that produces a racemic mixture of L-and D-lactate from sugar fermentation. The interconversion of lactate isomers is performed by a lactate racemase (Lar) that is transcriptionally controlled by the L-/Dlactate ratio and maximally induced in the presence of L-lactate. We previously reported that the Lar activity depends on the expression of two divergently oriented operons: (i) the larABCDE operon encodes the nickel-dependent lactate racemase (LarA), its maturases (LarBCE), and a lactic acid channel (LarD), and (ii) the larR (