The N-terminal region of Cdc6 specifically recognizes human DNA G-quadruplex.

Guanine (G)-rich nucleic acid sequences can form diverse G-quadruplex structures located in functionally significant genome regions, exerting regulatory control over essential biological processes, including DNA replication in vivo. During the initiation of DNA replication, Cdc6 is recruited by the origin recognition complex (ORC) to target specific chromosomal DNA sequences. This study reveals that human Cdc6 interacts with G-quadruplex structure through a distinct region within the N-terminal intrinsically disordered region (IDR), encompassing residues 7-20. The binding region assumes a hook-type conformation, as elucidated by the NMR solution structure in complex with htel21T18. Significantly, mutagenesis and in vivo investigations confirm the highly specific nature of Cdc6's recognition of G-quadruplex. This research enhances our understanding of the fundamental mechanism governing the interaction between G-quadruplex and the N-terminal IDR region of Cdc6, shedding light on the intricate regulation of DNA replication processes.

Neurotransmitter norepinephrine regulates chromatosomes aggregation and the formation of blotches in coral trout Plectropomus leopardus.

Color changes and pattern formations can represent strategies of the utmost importance for the survival of individuals or of species. Previous studies have associated capture with the formation of blotches (areas with light color) of coral trout, but the regulatory mechanisms link the two are lacking. Here, we report that capture induced blotches formation within 4-5 seconds. The blotches disappeared after anesthesia dispersed the pigment cells and reappeared after electrical stimulation. Subsequently, combining immunofluorescence, transmission electron microscopy and chemical sympathectomy, we found blotches formation results from activation of catecholaminergic neurons below the pigment layer. Finally, the in vitro incubation and intraperitoneal injection of norepinephrine (NE) induced aggregation of chromatosomes and lightening of body color, respectively, suggesting that NE, a neurotransmitter released by catecholaminergic nerves, mediates blotches formation. Our results demonstrate that acute stress response-induced neuronal activity can drive rapid changes in body color, which enriches our knowledge of physiological adaptations in coral reef fish.

Development of a dynamical statistical analog ensemble forecast model for landfalling typhoon disasters.

In this report, the development of a Dynamical Statistical Analog Ensemble Forecast model for landfalling typhoon disasters (LTDs) and some applications over coastal China are described. This model consists of the following four elements: (i) obtaining the forecast track of a target landfalling typhoon, (ii) constructing its generalized initial value (GIV), (iii) identifying its analogs based on the GIV, and (iv) assembling typhoon disasters of the analogs. Typhoon track, intensity, and landfall date are introduced in GIV at this early development stage. The pre-assessment results show that the mean threat scores of two important damage levels of LTDs reach 0.48 and 0.55, respectively. Of significance is that most of the damage occurs near the typhoon centers around the time of landfall. These results indicate the promising performance of the model in capturing the main damage characteristics of typhoon disasters, which would help coastal community mitigate damage from destructive typhoons.

Filamentous GLS1 promotes ROS-induced apoptosis upon glutamine deprivation via insufficient asparagine synthesis.

GLS1 orchestrates glutaminolysis and promotes cell proliferation when glutamine is abundant by regenerating TCA cycle intermediates and supporting redox homeostasis. CB-839, an inhibitor of GLS1, is currently under clinical investigation for a variety of cancer types. Here, we show that GLS1 facilitates apoptosis when glutamine is deprived. Mechanistically, the absence of exogenous glutamine sufficiently reduces glutamate levels to convert dimeric GLS1 to a self-assembled, extremely low-Km filamentous polymer. GLS1 filaments possess an enhanced catalytic activity, which further depletes intracellular glutamine. Functionally, filamentous GLS1-dependent glutamine scarcity leads to inadequate synthesis of asparagine and mitogenome-encoded proteins, resulting in ROS-induced apoptosis that can be rescued by asparagine supplementation. Physiologically, we observed GLS1 filaments in solid tumors and validated the tumor-suppressive role of constitutively active, filamentous GLS1 mutants K320A and S482C in xenograft models. Our results change our understanding of GLS1 in cancer metabolism and suggest the therapeutic potential of promoting GLS1 filament formation.

Sec13 promotes oligodendrocyte differentiation and myelin repair through autocrine pleiotrophin signaling.

Dysfunction of protein trafficking has been intensively associated with neurological diseases, including neurodegeneration, but whether and how protein transport contributes to oligodendrocyte (OL) maturation and myelin repair in white matter injury remains unclear. ER-to-Golgi trafficking of newly synthesized proteins is mediated by coat protein complex II (COPII). Here, we demonstrate that the COPII component Sec13 was essential for OL differentiation and postnatal myelination. Ablation of Sec13 in the OL lineage prevented OPC differentiation and inhibited myelination and remyelination after demyelinating injury in the central nervous system (CNS), while improving protein trafficking by tauroursodeoxycholic acid (TUDCA) or ectopic expression of COPII components accelerated myelination. COPII components were upregulated in OL lineage cells after demyelinating injury. Loss of Sec13 altered the secretome of OLs and inhibited the secretion of pleiotrophin (PTN), which was found to function as an autocrine factor to promote OL differentiation and myelin repair. These data suggest that Sec13-dependent protein transport is essential for OL differentiation and that Sec13-mediated PTN autocrine signaling is required for proper myelination and remyelination.

A Novel Algicidal Bacterium, Microbulbifer sp. YX04, Triggered Oxidative Damage and Autophagic Cell Death in Phaeocystis globosa, Which Causes Harmful Algal Blooms.

Phaeocystis globosa causes severe marine pollution by forming harmful algal blooms and releasing hemolytic toxins and is therefore harmful to marine ecosystems and aquaculture industries. In this study, Microbulbifer sp. YX04 exerted high algicidal activity against P. globosa by producing and secreting metabolites. The algicidal activity of the YX04 supernatant was stable after exposure to different temperatures (-80 to 100°C) and pH values (4 to 12) for 2 h, suggesting that algicidal substances could temporarily be stored under these temperature and pH value conditions. To explore the algicidal process and mechanism, morphological and structural changes, oxidative stress, photosynthesis, autophagic flux, and global gene expression were investigated. Biochemical analyses showed that the YX04 supernatant induced reactive oxygen species (ROS) overproduction, which caused lipid peroxidation and malondialdehyde (MDA) accumulation in P. globosa. Transmission electron microscopy (TEM) observation and the significant decrease in both maximum photochemical quantum yield (Fv/Fm) and relative electron transfer rate (rETR) indicated damage to thylakoid membranes and destruction of photosynthetic system function. Immunofluorescence, immunoblot, and TEM analyses indicated that cellular damage caused autophagosome formation and triggered large-scale autophagic flux in P. globosa. Transcriptome analysis revealed many P. globosa genes that were differentially expressed in response to YX04 stress, most of which were involved in photosynthesis, respiration, cytoskeleton, microtubule, and autophagosome formation and fusion processes, which may trigger autophagic cell death. In addition to P. globosa, the YX04 supernatant showed high algicidal activity against Thalassiosira pseudonana, Thalassiosira weissflogii, Skeletonema costatum, Heterosigma akashiwo, and Prorocentrum donghaiense. This study highlights multiple mechanisms underlying YX04 supernatant toxicity toward P. globosa and its potential for controlling the occurrence of harmful algal blooms. IMPORTANCEP. globosa is one of the most notorious harmful algal bloom (HAB)-causing species, which can secrete hemolytic toxins, frequently cause serious ecological pollution, and pose a health hazard to animals and humans. Hence, screening for bacteria with high algicidal activity against P. globosa and studies on the algicidal characteristics and mechanism will contribute to providing an ecofriendly microorganism-controlling agent for preventing the occurrence of algal blooms and reducing the harm of algal blooms to the environment. Our study first reported the algicidal characteristic and mechanism of Microbulbifer sp. YX04 against P. globosa and demonstrated that P. globosa shows different response mechanisms, including movement ability, antioxidative systems, photosynthetic systems, gene expression, and cell death mode, to adapt to the adverse environment when algicidal compounds are present.

An Effective Treatment of Perimenopausal Syndrome by Combining Two Traditional Prescriptions of Chinese Botanical Drugs.

Ethnopharmacological relevance: Two types of traditional Chinese formulas of botanical drugs are prescribed for treating perimenopausal syndrome (PMS), a disorder in middle-aged women during their transition to menopause. One is for treating PMS as kidney deficiency (KD) due to senescence and declining reproductive functions, and the other is for treating it as liver qi stagnation (LQS) in association with stress and anxiety. Despite the time-tested prescriptions, an objective attestation to the effectiveness of the traditional Chinese treatment of PMS is still to be established and the associated molecular mechanism is still to be investigated. Materials and methods: A model for PMS was generated from perimenopausal rats with chronic restraint stress (CRS). The effectiveness of traditional Chinese formulas of botanical drugs and a combination of two of the formulas was evaluated based on 1H NMR plasma metabolomic, as well as behavioral and physiological, indicators. To investigate whether the formulas contained ligands that could compensate for the declining level of estrogen, the primary cause of PMS, the ligand-based NMR technique of saturation transfer difference (STD) was employed to detect possible interacting molecules to estrogen receptors in the decoction. Results: Each prescription of the classical Chinese formula moderately attenuated the metabolomic state of the disease model. The best treatment strategy however was to combine two traditional Chinese formulas, each for a different etiology, to adjust the metabolomic state of the disease model to that of rats at a much younger age. In addition, this attenuation of the metabolomics of the disease model was by neither upregulating the estrogen level nor supplementing an estrogenic compound. Conclusion: Treatment of PMS with a traditional Chinese formula of botanical drugs targeting one of the two causes separately could ameliorate the disorder moderately. However, the best outcome was to treat the two causes simultaneously with a decoction that combined ingredients from two traditional prescriptions. The data also implicated a new paradigm for phytotherapy of PMS as the prescribed decoctions contained no interacting compound to modulate the activity of estrogen receptors, in contrast to the treatment strategy of hormone replacement therapy.

The Metabolomic Rationale for Treating Perimenopausal Syndrome as Kidney Deficiency.

BACKGROUND: Traditional Chinese medicine (TCM) typically attributes the etiopathogenesis of perimenopausal syndrome (PMS) to kidney deficiency in the TCM stratification system for diagnosis. However, the molecular basis of this classical attribution remains to be investigated. Aim of the Study. By unraveling the responses to TCM treatment for kidney deficiency, the metabolomic link between PMS and kidney deficiency can be evaluated for in-depth understanding of the mechanism of TCM treatment and development of better treatment protocols. MATERIALS AND METHODS: With naturally aged rats as a model for PMS, the metabolomic response to TCM treatment for kidney deficiency was investigated by 1H NMR. RESULTS: 1H NMR metabolomic evidence of plasma samples demonstrates that treatments with two classical TCM prescriptions for kidney deficiency, decoctions of Yougui and Zuogui, result in modulating the metabolic state of the disease model towards that of rats of younger age. CONCLUSION: The data support the notion that kidney deficiency is responsible, in part at least, for PMS, and the relevant prescriptions are helpful in dampening the changes in the body's metabolic states to alleviate symptoms of the disorder.

Fragment-wise design of inhibitors to 3C proteinase from enterovirus 71.

BACKGROUND: Enterovirus 71 (EV71) is a causative agent of hand, foot and mouth disease (HFMD), which can spread its infection to central nervous and other systems with severe consequence. A key factor in the replication of EV71 is its 3C proteinase (3C(pro)), a significant drug target. Peptidomimetics were employed as inhibitors of this enzyme for developing antivirals. However, the peptide bonds in these peptidomimetics are a source of low bioavailability due to their susceptibility to protease digestion. To produce non-peptidomimetic inhibitors by replacing these peptide bonds, it would be important to gain better understanding on the contribution of each component to the interaction and potency. METHODS: A series of compounds of different lengths targeting 3C(pro) and having an α,ß-unsaturated ester as the warhead were synthesized and their interactions with the enzyme were evaluated by complex structure analyses and potency assays for a better understanding on the relationship between potency and evolution of interaction. RESULTS: The P2 moiety of the compound would need to be oriented to interact in the S2 site in the substrate binding cleft and the P3-P4 moieties were required to generate sufficient potency. A hydrophobic terminal group will benefit the cellular uptake and improve the activity in vivo. CONCLUSIONS AND GENERAL SIGNIFICANCE: The data presented here provide a basis for designing a new generation of non-peptidomimetics to target EV71 3C(pro).

Structures of Enterovirus 71 3C proteinase (strain E2004104-TW-CDC) and its complex with rupintrivir.

The crystal structure of 3C proteinase (3C(pro)) from Enterovirus 71 (EV71) was determined in space group C2221 to 2.2 Šresolution. The fold was similar to that of 3C(pro) from other picornaviruses, but the difference in the ß-ribbon reported in a previous structure was not observed. This ß-ribbon was folded over the substrate-binding cleft and constituted part of the essential binding sites for interaction with the substrate. The structure of its complex with rupintrivir (AG7088), a peptidomimetic inhibitor, was also characterized in space group P212121 to 1.96 Šresolution. The inhibitor was accommodated without any spatial hindrance despite the more constricted binding site; this was confirmed by functional assays, in which the inhibitor showed comparable potency towards EV71 3C(pro) and human rhinovirus 3C(pro), which is the target that rupintrivir was designed against.

Conformational plasticity of the 2A proteinase from enterovirus 71.

The 2A proteinase (2A(pro)) is an enterovirally encoded cysteine protease that plays essential roles in both the processing of viral precursor polyprotein and the hijacking of host cell translation and other processes in the virus life cycle. Crystallographic studies of 2A(pro) from enterovirus 71 (EV71) and its interaction with the substrate are reported here. EV71 2A(pro) was comprised of an N-terminal domain of a four-stranded antiparallel ß sheet and a C-terminal domain of a six-stranded antiparallel ß barrel with a tightly bound zinc atom. Unlike in other 2A(pro) structures, there is an open cleft across the surface of the protein in an open conformation. As demonstrated by the crystallographic studies and modeling of the complex structure, the open cleft could be fitted with the substrate. On comparison 2A(pro) of EV71 to those of the human rhinovirus 2 and coxsackievirus B4, the open conformation could be closed with a hinge motion in the bII2 and cII ß strands. This was supported by molecular dynamic simulation. The structural variation among different 2A(pro) structures indicates a conformational flexibility in the substrate-binding cleft. The open structure provides an accessible framework for the design and development of therapeutics against the viral target.

The hemagglutinin structure of an avian H1N1 influenza A virus.

The interaction between hemagglutinin (HA) and receptors is a kernel in the study of evolution and host adaptation of H1N1 influenza A viruses. The notion that the avian HA is associated with preferential specificity for receptors with Siaalpha2,3Gal glycosidic linkage over those with Siaalpha2,6Gal linkage is not all consistent with the available data on H1N1 viruses. By x-ray crystallography, the HA structure of an avian H1N1 influenza A virus, as well as its complexes with the receptor analogs, was determined. The structures revealed no preferential binding of avian receptor analogs over that of the human analog, suggesting that the HA/receptor binding might not be as stringent as is commonly believed in determining the host receptor preference for some subtypes of influenza viruses, such as the H1N1 viruses. The structure also showed difference in glycosylation despite the preservation of related sequences, which may partly contribute to the difference between structures of human and avian origin.