A glimpse into the hidden world of the flexible C-terminal protein binding domains of human RAD52.

Human RAD52 protein binds DNA and is involved in genomic stability maintenance and several forms of DNA repair, including homologous recombination and single-strand annealing. Despite its importance, there are very few structural details about the variability of the RAD52 ring size and the RAD52 C-terminal protein-protein interaction domains. Even recent attempts to employ cryogenic electron microscopy (cryoEM) methods on full-length yeast and human RAD52 do not reveal interpretable structures for the C-terminal half that contains the replication protein A (RPA) and RAD51 binding domains.

Revealing the atomic and electronic mechanism of human manganese superoxide dismutase product inhibition.

Human manganese superoxide dismutase (MnSOD) is a crucial oxidoreductase that maintains the vitality of mitochondria by converting superoxide (O) to molecular oxygen (O) and hydrogen peroxide (HO) with proton-coupled electron transfers (PCETs). Human MnSOD has evolved to be highly product inhibited to limit the formation of HO, a freely diffusible oxidant and signaling molecule. The product-inhibited complex is thought to be composed of a peroxide (O) or hydroperoxide (HO) species bound to Mn ion and formed from an unknown PCET mechanism.

Up-Regulation of Non-Homologous End-Joining by MUC1.

Ionizing radiation (IR) and chemotherapy with DNA-damaging drugs such as cisplatin are vital cancer treatment options. These treatments induce double-strand breaks (DSBs) as cytotoxic DNA damage; thus, the DSB repair activity in each cancer cell significantly influences the efficacy of the treatments. Pancreatic cancers are known to be resistant to these treatments, and the overexpression of MUC1, a member of the glycoprotein mucins, is associated with IR- and chemo-resistance.

Ligand-installed polymeric nanocarriers for combination chemotherapy of EGFR-positive ovarian cancer.

Combination chemotherapeutic drugs administered via a single nanocarrier for cancer treatment provides benefits in reducing dose-limiting toxicities, improving the pharmacokinetic properties of the cargo and achieving spatial-temporal synchronization of drug exposure for maximized synergistic therapeutic effects. In an attempt to develop such a multi-drug carrier, our work focuses on functional multimodal polypeptide-based polymeric nanogels (NGs). Diblock copolymers poly (ethylene glycol)-b-poly (glutamic acid) (PEG-b-PGlu) modified with phenylalanine (Phe) were successfully synthesized and characterized.

Perfect Crystals: microgravity capillary counterdiffusion crystallization of human manganese superoxide dismutase for neutron crystallography.

The NASA mission Perfect Crystals used the microgravity environment on the International Space Station (ISS) to grow crystals of human manganese superoxide dismutase (MnSOD)-an oxidoreductase critical for mitochondrial vitality and human health. The mission's overarching aim is to perform neutron protein crystallography (NPC) on MnSOD to directly visualize proton positions and derive a chemical understanding of the concerted proton electron transfers performed by the enzyme. Large crystals that are perfect enough to diffract neutrons to sufficient resolution are essential for NPC.

SPRTN and TDP1/TDP2 Independently Suppress 5-Aza-2'-deoxycytidine-Induced Genomic Instability in Human TK6 Cell Line.

DNA-protein cross-links (DPCs) are generated by internal factors such as cellular aldehydes that are generated during normal metabolism and external factors such as environmental mutagens. A nucleoside analog, 5-aza-2'-deoxycytidine (5-azadC), is randomly incorporated into the genome during DNA replication and binds DNA methyltransferase 1 (DNMT1) covalently to form DNMT1-DPCs without inducing DNA strand breaks. Despite the recent progress in understanding the mechanisms of DPCs repair, how DNMT1-DPCs are repaired is unclear.

EWALD: A macromolecular diffractometer for the second target station.

Revealing the positions of all the atoms in large macromolecules is powerful but only possible with neutron macromolecular crystallography (NMC). Neutrons provide a sensitive and gentle probe for the direct detection of protonation states at near-physiological temperatures and clean of artifacts caused by x rays or electrons. Currently, NMC use is restricted by the requirement for large crystal volumes even at state-of-the-art instruments such as the macromolecular neutron diffractometer at the Spallation Neutron Source.

Cryotrapping peroxide in the active site of human mitochondrial manganese superoxide dismutase crystals for neutron diffraction.

Structurally identifying the enzymatic intermediates of redox proteins has been elusive due to difficulty in resolving the H atoms involved in catalysis and the susceptibility of ligand complexes to photoreduction from X-rays. Cryotrapping ligands for neutron protein crystallography combines two powerful tools that offer the advantage of directly identifying hydrogen positions in redox-enzyme intermediates without radiolytic perturbation of metal-containing active sites. However, translating cryogenic techniques from X-ray to neutron crystallography is not straightforward due to the large crystal volumes and long data-collection times.

The 3,4-Quinones of Estrone and Estradiol Are the Initiators of Cancer whereas Resveratrol and -acetylcysteine Are the Preventers.

This article reviews evidence suggesting that a common mechanism of initiation leads to the development of many prevalent types of cancer. Endogenous estrogens, in the form of catechol estrogen-3,4-quinones, play a central role in this pathway of cancer initiation. The catechol estrogen-3,4-quinones react with specific purine bases in DNA to form depurinating estrogen-DNA adducts that generate apurinic sites.

Are the St John's wort Hyp-1 superstructures different?

Two commensurately modulated structures (PDB entries 4n3e and 6sjj) were solved using translational noncrystallographic symmetry (tNCS). The data required the use of large supercells, sevenfold and ninefold, respectively, to properly index the reflections. Commensurately modulated structures can be challenging to solve.

Direct detection of coupled proton and electron transfers in human manganese superoxide dismutase.

Human manganese superoxide dismutase is a critical oxidoreductase found in the mitochondrial matrix. Concerted proton and electron transfers are used by the enzyme to rid the mitochondria of O. The mechanisms of concerted transfer enzymes are typically unknown due to the difficulties in detecting the protonation states of specific residues and solvent molecules at particular redox states.

The role of tumor heterogeneity in immune-tumor interactions.

The development of cancer stems from genetic instability and changes in genomic sequences, and hence, the heterogeneity exhibited by tumors is integral to the nature of cancer itself. Tumor heterogeneity can be further altered by factors that are not cancer cell intrinsic, i.e.

Catalytically inactive Dnmt3b rescues mouse embryonic development by accessory and repressive functions.

DNA methylation regulates gene expression in a variety of processes, including mouse embryonic development. Four catalytically active enzymes function in mice as DNA methyltransferases (Dnmts) and as transcriptional regulators. Inactivation of Dnmt3b results in mouse embryonic lethality, but which activities are involved is unclear.

BraggNet: integrating Bragg peaks using neural networks.

Neutron crystallography offers enormous potential to complement structures from X-ray crystallography by clarifying the positions of low- elements, namely hydrogen. Macromolecular neutron crystallography, however, remains limited, in part owing to the challenge of integrating peak shapes from pulsed-source experiments. To advance existing software, this article demonstrates the use of machine learning to refine peak locations, predict peak shapes and yield more accurate integrated intensities when applied to whole data sets from a protein crystal.

Inactivation of XPF Sensitizes Cancer Cells to Gemcitabine.

Gemcitabine (2', 2'-difluorodeoxycytidine; dFdC) is a deoxycytidine analog and is used primarily against pancreatic cancer. The cytotoxicity of gemcitabine is due to the inhibition of DNA replication. However, a mechanism of removal of the incorporated dFdC is largely unknown.

A simple fluorescent assay for the discovery of protein-protein interaction inhibitors.

Due to the therapeutic potential of targeting protein-protein interactions (PPIs) there is a need for easily executed assays to perform high throughput screening (HTS) of inhibitors. We have developed and optimized an innovative and robust fluorescence-based assay for detecting PPI inhibitors, called FluorIA (Fluorescence-based protein-protein Interaction Assay). Targeting the PPI of RAD52 with replication protein A (RPA) was used as an example, and the FluorIA protocol design, optimization and successful application to HTS of large chemical libraries are described.

Tumor-stromal crosstalk in pancreatic cancer and tissue fibrosis.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with high morbidity and mortality worldwide. To date, limited therapeutic achievements targeting cell proliferation and related mechanisms has led researchers to focus on the microenvironment where pancreatic cancers develop. The anomalous proliferation of stromal cells, such as pancreatic stellate cells, and an increased deposition of altered matrix proteins create an environment that facilitates tumor growth, metastasis and drug resistance.

Superoxide Dismutases (SODs) and SOD Mimetics.

Superoxide dismutase (SOD) is the only known enzyme to directly scavenge a free radical. [..

Redox manipulation of the manganese metal in human manganese superoxide dismutase for neutron diffraction.

Human manganese superoxide dismutase (MnSOD) is one of the most significant enzymes in preventing mitochondrial dysfunction and related diseases by combating reactive oxygen species (ROS) in the mitochondrial matrix. Mitochondria are the source of up to 90% of cellular ROS generation, and MnSOD performs its necessary bioprotective role by converting superoxide into oxygen and hydrogen peroxide. This vital catalytic function is conducted via cyclic redox reactions between the substrate and the active-site manganese using proton-coupled electron transfers.

Use of Endoscopic Ultrasound in a Diagnostic Dilemma: Metastatic Breast Cancer to the Stomach.

A 55-year-old woman presented with persistent nausea, vomiting, and weight loss previously attributed to Ménétrier's disease. On further workup, she was found to have metastatic lobular breast carcinoma causing gastric outlet obstruction, diagnosed by endoscopic ultrasound with fine needle aspiration after previous gastric mucosal biopsies were unremarkable. In most reported cases of gastric metastasis from breast cancer, a diagnosis was established by mucosal biopsy.

Hybrid Donor-Acceptor Polymer Particles with Amplified Energy Transfer for Detection and On-Demand Treatment of Breast Cancer.

Judicious combination of semiconducting polymers with alternating electron donor (D) and acceptor (A) segments created hybrid nanoparticles with amplified energy transfer and red-shifted emission, while simultaneously providing photothermal capabilities. Hybrid D-A polymer particles (H-DAPPs) passively localized within orthotopic breast tumors, serving as bright fluorescent beacons. Laser stimulation induced heat generation on par with gold nanorods, resulting in selective destruction of the tumor.

A Review of the Catalytic Mechanism of Human Manganese Superoxide Dismutase.

Superoxide dismutases (SODs) are necessary antioxidant enzymes that protect cells from reactive oxygen species (ROS). Decreased levels of SODs or mutations that affect their catalytic activity have serious phenotypic consequences. SODs perform their bio-protective role by converting superoxide into oxygen and hydrogen peroxide by cyclic oxidation and reduction reactions with the active site metal.

Combination of mAb-AR20.5, anti-PD-L1 and PolyICLC inhibits tumor progression and prolongs survival of MUC1.Tg mice challenged with pancreatic tumors.

A substantial body of evidence suggests the existence of MUC1-specific antibodies and cytotoxic T cell activities in pancreatic cancer patients. However, tumor-induced immunosuppression renders these responses ineffective. The current study explores a novel therapeutic combination wherein tumor-bearing hosts can be immunologically primed with their own antigen, through opsonization with a tumor antigen-targeted antibody, mAb-AR20.

Ccdc3: A New P63 Target Involved in Regulation Of Liver Lipid Metabolism.

TAp63, a member of the p53 family, has been shown to regulate energy metabolism. Here, we report coiled coil domain-containing 3 (CCDC3) as a new TAp63 target. TAp63, but not ΔNp63, p53 or p73, upregulates CCDC3 expression by directly binding to its enhancer region.