The Role of Microhomology-Mediated End Joining (MMEJ) at Dysfunctional Telomeres.

DNA double-strand break (DSB) repair pathways are crucial for maintaining genome stability and cell viability. However, these pathways can mistakenly recognize chromosome ends as DNA breaks, leading to adverse outcomes such as telomere fusions and malignant transformation. The shelterin complex protects telomeres from activation of DNA repair pathways by inhibiting nonhomologous end joining (NHEJ), homologous recombination (HR), and microhomology-mediated end joining (MMEJ).

Ultrathin, large area β-Ni(OH) crystalline nanosheet as bifunctional electrode material for charge storage and oxygen evolution reaction.

Bifunctional electrode materials are highly desirable for meeting increasing global energy demands and mitigating environmental impact. However, improving the atom-efficiency, scalability, and cost-effectiveness of storage systems, as well as optimizing conversion processes to enhance overall energy utilization and sustainability, remains a significant challenge for their application. Herein, we devised an optimized, facile, economic, and scalable synthesis of large area (cm), ultrathin (∼2.

Microhomology-Mediated End-Joining Chronicles: Tracing the Evolutionary Footprints of Genome Protection.

The fidelity of genetic information is essential for cellular function and viability. DNA double-strand breaks (DSBs) pose a significant threat to genome integrity, necessitating efficient repair mechanisms. While the predominant repair strategies are usually accurate, paradoxically, error-prone pathways also exist.

Mitochondrial DNA breaks activate an integrated stress response to reestablish homeostasis.

Mitochondrial DNA double-strand breaks (mtDSBs) lead to the degradation of circular genomes and a reduction in copy number; yet, the cellular response in human cells remains elusive. Here, using mitochondrial-targeted restriction enzymes, we show that a subset of cells with mtDSBs exhibited defective mitochondrial protein import, reduced respiratory complexes, and loss of membrane potential. Electron microscopy confirmed the altered mitochondrial membrane and cristae ultrastructure.

Risk Factors with Porcelain Laminate Veneers Experienced during Cementation: A Review.

The clinical success of porcelain laminate veneers (PLVs) depends on many clinical and technical factors, from planning to execution, among which adhesive cementation is of significant importance. This procedure carries many risk factors if not optimally executed. The objective of this study was to document the clinical parameters affecting successful cementation procedures with a focus on the adhesive strength, integrity, and esthetics of the PLVs.

Switching on/off molybdenum nitride catalytic activity in ammonia synthesis through modulating metal-support interaction.

Modulating the interaction between Mo nanoparticles and their support is an elegant approach to finely tune the structural, physico-chemical, redox and electronic properties of the active site. In this work, a series of molybdenum nitride catalysts supported on TiO, and SBA-15 has been prepared and fully characterized. The results of characterization confirmed the high dispersion of Mo and the formation of small molybdenum nanoparticles in both the 10-Mo-N/SBA-15 and 10-Mo-N/TiO catalysts.

RHINO restricts MMEJ activity to mitosis.

DNA double-strand breaks (DSBs) are toxic lesions that can lead to genome instability if not properly repaired. Breaks incurred in G1 phase of the cell cycle are predominantly fixed by non-homologous end-joining (NHEJ), while homologous recombination (HR) is the primary repair pathway in S and G2. Microhomology-mediated end-joining (MMEJ) is intrinsically error-prone and considered a backup DSB repair pathway that becomes essential when HR and NHEJ are compromised.

Identification of , an Orally Bioavailable Compound that Inhibits the DNA Polymerase Activity of Polθ.

DNA polymerase theta (Polθ) is an attractive synthetic lethal target for drug discovery, predicted to be efficacious against breast and ovarian cancers harboring BRCA-mutant alleles. Here, we describe our hit-to-lead efforts in search of a selective inhibitor of human Polθ (encoded by POLQ). A high-throughput screening campaign of 350,000 compounds identified an 11 micromolar hit, giving rise to the N2-substituted fused pyrazolo series, which was validated by biophysical methods.

Basic science under threat: Lessons from the Skirball Institute.

Support for basic science has been eclipsed by initiatives aimed at specific medical problems. The latest example is the dismantling of the Skirball Institute at NYU School of Medicine. Here, we reflect on the achievements and mission underlying the Skirball to gain insight into the dividends of maintaining a basic science vision within the academic enterprises.

Rap1 regulates TIP60 function during fate transition between two-cell-like and pluripotent states.

In mammals, the conserved telomere binding protein Rap1 serves a diverse set of nontelomeric functions, including activation of the NF-kB signaling pathway, maintenance of metabolic function in vivo, and transcriptional regulation. Here, we uncover the mechanism by which Rap1 modulates gene expression. Using a separation-of-function allele, we show that Rap1 transcriptional regulation is largely independent of TRF2-mediated binding to telomeres and does not involve direct binding to genomic loci.

Stem cells at odds with telomere maintenance and protection.

Telomeres are distinctive structures that protect the ends of linear chromosomes and ensure genome stability. They are composed of long tracks of repetitive and G-rich DNA that is bound by shelterin, a dedicated six-subunit protein complex. In somatic cells, shelterin protects telomeres from the DNA damage response and regulates telomere length.

Litter decomposition by soil fauna: effect of land use in agroecosystems.

Soil fauna plays a key role in organic matter decomposition. Litter decomposition depends on the relationships of soil fauna and microorganisms as well as climate and litter quality. The decomposer community is sensitive to land use.

Alternative splicing is a developmental switch for hTERT expression.

Telomere length control is critical for cellular lifespan and tumor suppression. Telomerase is transiently activated in the inner cell mass of the developing blastocyst to reset telomere reserves. Its silencing upon differentiation leads to gradual telomere shortening in somatic cells.

Nuclear sensing of breaks in mitochondrial DNA enhances immune surveillance.

Mitochondrial DNA double-strand breaks (mtDSBs) are toxic lesions that compromise the integrity of mitochondrial DNA (mtDNA) and alter mitochondrial function. Communication between mitochondria and the nucleus is essential to maintain cellular homeostasis; however, the nuclear response to mtDSBs remains unknown. Here, using mitochondrial-targeted transcription activator-like effector nucleases (TALENs), we show that mtDSBs activate a type-I interferon response that involves the phosphorylation of STAT1 and activation of interferon-stimulated genes.

Quantitative Imaging of MS2-Tagged hTR in Cajal Bodies: Photobleaching and Photoactivation.

Advances in imaging technologies, gene editing, and fluorescent molecule development have made real-time imaging of nucleic acids practical. Here, we detail methods for imaging the human telomerase RNA template, hTR via the use of three inserted MS2 stem loops and cognate MS2 coat protein (MCP) tagged with superfolder GFP or photoactivatable GFP. These technologies enable tracking of the dynamics of RNA species through Cajal bodies and offer insight into their residence time in Cajal bodies through photobleaching and photoactivation experiments.

A single-molecule view of telomerase regulation at telomeres.

Telomerase plays a key role in the immortalization of cancer cells by maintaining telomeres length. Using single-molecule imaging of telomerase RNA molecules in cancer cells, we recently reported novel insights into the role of Cajal bodies in telomerase biogenesis and the regulation of telomerase recruitment to telomeres.

In Vivo Analysis of mtDNA Replication at the Single Molecule Level and with High Resolution.

Single molecule analysis of replicating DNA (SMARD) is a powerful methodology that allows in vivo analysis of replicating DNA; identification of origins of replication, assessment of fork directionality, and measurement of replication fork speed. SMARD, which has been extensively used to study replication of nuclear DNA, involves incorporation of thymidine analogs to nascent DNA chains and their subsequent visualization through immune detection. Here, we adapt and fine-tune the SMARD technique to the specifics of human and mouse mitochondrial DNA.

Replication stress conferred by POT1 dysfunction promotes telomere relocalization to the nuclear pore.

Mutations in the telomere-binding protein POT1 are associated with solid tumors and leukemias. POT1 alterations cause rapid telomere elongation, ATR kinase activation, telomere fragility, and accelerated tumor development. Here, we define the impact of mutant alleles through complementary genetic and proteomic approaches based on CRISPR interference and biotin-based proximity labeling, respectively.

Imaging of Telomerase RNA by Single-Molecule Inexpensive FISH Combined with Immunofluorescence.

Fluorescent hybridization (FISH) on the RNA moiety of human telomerase (hTR) with 50-mer probes detects hTR RNA accumulated in Cajal bodies. Using both live-cell imaging and single-molecule inexpensive FISH, our published work revealed that only a fraction of hTR localizes to Cajal bodies, with the majority of hTR molecules distributed throughout the nucleoplasm. This protocol is an application guide to the smiFISH method for the dual detection of hTR RNA and telomeres or Cajal bodies by immunofluorescence.

Safeguarding mitochondrial genomes in higher eukaryotes.

Mitochondria respond to DNA damage and preserve their own genetic material in a manner distinct from that of the nucleus but that requires organized mito-nuclear communication. Failure to resolve mtDNA breaks leads to mitochondrial dysfunction and affects host cells and tissues. Here, we review the pathways that safeguard mitochondrial genomes and examine the insights gained from studies of cellular and tissue-wide responses to mtDNA damage and mito-nuclear genome incompatibility.