Structural basis for product specificities of MLL family methyltransferases.

Human mixed-lineage leukemia (MLL) family methyltransferases methylate histone H3 lysine 4 to different methylation states (me1/me2/me3) with distinct functional outputs, but the mechanism underlying the different product specificities of MLL proteins remains unclear. Here, we develop methodologies to quantitatively measure the methylation rate difference between mono-, di-, and tri-methylation steps and demonstrate that MLL proteins possess distinct product specificities in the context of the minimum MLL-RBBP5-ASH2L complex. Comparative structural analyses of MLL complexes by X-ray crystal structures, fluorine-19 nuclear magnetic resonance, and molecular dynamics simulations reveal that the dynamics of two conserved tyrosine residues at the "F/Y (phenylalanine/tyrosine) switch" positions fine-tune the product specificity. The variation in the intramolecular interaction between SET-N and SET-C affects the F/Y switch dynamics, thus determining the product specificities of MLL proteins. These results indicate a modified F/Y switch rule applicable for most SET domain methyltransferases and implicate the functional divergence of MLL proteins.

Checkpoint kinase 2 controls insulin secretion and glucose homeostasis.

After the discovery of insulin, a century ago, extensive work has been done to unravel the molecular network regulating insulin secretion. Here we performed a chemical screen and identified AZD7762, a compound that potentiates glucose-stimulated insulin secretion (GSIS) of a human ß cell line, healthy and type 2 diabetic (T2D) human islets and primary cynomolgus macaque islets. In vivo studies in diabetic mouse models and cynomolgus macaques demonstrated that AZD7762 enhances GSIS and improves glucose tolerance. Furthermore, genetic manipulation confirmed that ablation of CHEK2 in human ß cells results in increased insulin secretion. Consistently, high-fat-diet-fed Chk2-/- mice show elevated insulin secretion and improved glucose clearance. Finally, untargeted metabolic profiling demonstrated the key role of the CHEK2-PP2A-PLK1-G6PD-PPP pathway in insulin secretion. This study successfully identifies a previously unknown insulin secretion regulating pathway that is conserved across rodents, cynomolgus macaques and human ß cells in both healthy and T2D conditions.

Cooperative interaction of CST and RECQ4 resolves G-quadruplexes and maintains telomere stability.

Human CST (CTC1-STN1-TEN1) is a ssDNA-binding complex that interacts with the replisome to aid in stalled fork rescue. We previously found that CST promotes telomere replication to maintain genomic integrity via G-quadruplex (G4) resolution. However, the detailed mechanism by which CST resolves G4s in vivo and whether additional factors are involved remains unclear. Here, we identify RECQ4 as a novel CST-interacting partner and show that RECQ4 can unwind G4 structures in vitro using a FRET assay. Moreover, G4s accumulate at the telomere after RECQ4 depletion, resulting in telomere dysfunction, including the formation of MTSs, SFEs, and TIFs, suggesting that RECQ4 is crucial for telomere integrity. Furthermore, CST is also required for RECQ4 telomere or chromatin localization in response to G4 stabilizers. RECQ4 is involved in preserving genomic stability by CST and RECQ4 disruption impairs restart of replication forks stalled by G4s. Overall, our findings highlight the essential roles of CST and RECQ4 in resolving G-rich regions, where they collaborate to resolve G4-induced replication deficiencies and maintain genomic homeostasis.

Propagation properties of elegant modified Bessel Gaussian beams.

A kind of optical beam with a radially parabolic propagating manner and intensity decay inversely proportional to propagating distance in the far field is investigated. The initial complex amplitudes of this kind of beam have the form of a Gaussian function multiplied by a m/2-order modified Bessel function and a helical phase factor with topological charge m. The arguments for Bessel and Gauss parts in the propagating solutions of these beams are complex and symmetric as elegant Laguerre and Hermite Gaussian beams. As a result, the beams can be referred to as elegant modified Bessel Gauss (EMBG) beams. Similar to non-diffractive beams such as Bessel and Airy beams, the EMBG beams also carry infinite power due to a transversely slowly decaying tail of complex amplitude. The EMBG beams demonstrate intermediate propagating properties between non-diffractive and finite-power beams. Unlike non-diffractive beams that never spread their power and finite-power beams that always diverge in a linear manner and spread their power by inversely square law in the far field, the EMBG beams demonstrate a far-field parabolic propagating manner and decay their power by inversely linear law. In addition, the EMBG beams have total Gouy phase, which is only half of that of elegant Laguerre Gauss beams with the same topological charge, and have far-field intensity distributions regardless of the beam waist radius in the initial plane. The propagating and focusing properties of EMBG beams represent an intermediate status between the non-diffractive and finite-power beams.

Dihydroartemisinin enhances the anti-tumour effect of photodynamic therapy by targeting PKM2-mediated glycolysis in oesophageal cancer cell.

Photodynamic therapy (PDT) has been demonstrated to provide immediate relief of oesophageal cancer patients' re-obstruction and extend their lifespan. However, tumour regrowth may occur after PDT due to enhanced aerobic glycolysis. Previous research has confirmed the inhibitory effect of Dihydroartemisinin (DHA) on aerobic glycolysis. Therefore, the current study intends to investigate the function and molecular mechanism of DHA targeting tumour cell aerobic glycolysis in synergia PDT. The combined treatment significantly suppressed glycolysis in vitro and in vivo compared to either monotherapy. Exploration of the mechanism through corresponding experiments revealed that pyruvate kinase M2 (PKM2) was downregulated in treated cells, whereas overexpression of PKM2 nullified the inhibitory effects of DHA and PDT. This study proposes a novel therapeutic strategy for oesophageal cancer through DHA-synergized PDT treatment, targeting inhibit PKM2 to reduce tumour cell proliferation and metastasis.

A glutaminase isoform switch drives therapeutic resistance and disease progression of prostate cancer.

Cellular metabolism in cancer is significantly altered to support the uncontrolled tumor growth. How metabolic alterations contribute to hormonal therapy resistance and disease progression in prostate cancer (PCa) remains poorly understood. Here we report a glutaminase isoform switch mechanism that mediates the initial therapeutic effect but eventual failure of hormonal therapy of PCa. Androgen deprivation therapy inhibits the expression of kidney-type glutaminase (KGA), a splicing isoform of glutaminase 1 (GLS1) up-regulated by androgen receptor (AR), to achieve therapeutic effect by suppressing glutaminolysis. Eventually the tumor cells switch to the expression of glutaminase C (GAC), an androgen-independent GLS1 isoform with more potent enzymatic activity, under the androgen-deprived condition. This switch leads to increased glutamine utilization, hyperproliferation, and aggressive behavior of tumor cells. Pharmacological inhibition or RNA interference of GAC shows better treatment effect for castration-resistant PCa than for hormone-sensitive PCa in vitro and in vivo. In summary, we have identified a metabolic function of AR action in PCa and discovered that the GLS1 isoform switch is one of the key mechanisms in therapeutic resistance and disease progression.

The Genus Cladosporium: A Prospective Producer of Natural Products.

Cladosporium, a genus of ascomycete fungi in the Dematiaceae family, is primarily recognized as a widespread environmental saprotrophic fungus or plant endophyte. Further research has shown that the genus is distributed in various environments, particularly in marine ecosystems, such as coral reefs, mangroves and the polar region. Cladosporium, especially the marine-derived Cladosporium, is a highly resourceful group of fungi whose natural products have garnered attention due to their diverse chemical structures and biological activities, as well as their potential as sources of novel leads to compounds for drug production. This review covers the sources, distribution, bioactivities, biosynthesis and structural characteristics of compounds isolated from Cladosporium in the period between January 2000 and December 2022, and conducts a comparative analysis of the Cladosporium isolated compounds derived from marine and terrestrial sources. Our results reveal that 34% of Cladosporium-derived natural products are reported for the first time. And 71.79% of the first reported compounds were isolated from marine-derived Cladosporium. Cladosporium-derived compounds exhibit diverse skeletal chemical structures, concentrating in the categories of polyketides (48.47%), alkaloids (19.21%), steroids and terpenoids (17.03%). Over half of the natural products isolated from Cladosporium have been found to have various biological activities, including cytotoxic, antibacterial, antiviral, antifungal and enzyme-inhibitory activities. These findings testify to the tremendous potential of Cladosporium, especially the marine-derived Cladosporium, to yield novel bioactive natural products, providing a structural foundation for the development of new drugs.

Caspase-6 is a key regulator of cross-talk signal way in PANoptosis in cancer.

Cysteinyl aspartate specific proteinase (caspase)-6 belongs to the caspase family and plays a vital role in mediating cell death. Under certain conditions, three pathways of programmed cell death (PCD), including apoptosis, necroptosis and pyroptosis (PANoptosis), transform one way into another, with enormous therapeutic potential. Initially, scholars reported that caspase-6 is a caspase executor that mediates apoptosis. With the ceaseless exploration of the PCD types, studies have demonstrated that caspase-6 mediates pyroptosis by regulating gasdermin D and mediates necroptosis by regulating mixed lineage kinase domain-like. By regulating PANoptosis, caspase-6 plays a crucial role in tumorigenesis in humans and mediates anti-tumour immunity. Therefore, a comprehensive understanding of caspase-6 function in cancer via PANoptosis is important for the prevention and therapy of tumours. This article summarized the function of caspase-6 in PANoptosis and its impact on cancer development, providing targets and strategies for tumour treatment.

Propagating analysis of Airy beams via complex phase space and ray method.

A complex phase space and ray method is proposed to present intuitive interpretation of unique intensity profiles, parabolic accelerating trajectories, and distinctive phase shifts of Airy beam and its exponentially decaying version (i.e., finite-energy Airy beam). In the complex phase space, finite-energy Airy beam manifests itself as a complex parabolic phase space curve (PSC) which represents a cluster of light rays with complex wave vectors. The complex ray cluster converges to a complex parabolic caustic curve in complex coordinate space. For infinite-energy Airy beam, phase space, PSC, light ray and caustic curve change to real values. In the paraxial condition, Airy beams can maintain parabolic form of PSC and keep constant ray density, which guarantees the non-diffraction property of Airy beam and approximate non-diffraction property of finite-energy Airy beam. From the evolution of vertexes of parabolic PSC along a parabolic trajectory in phase space, one can also give the parabolic caustic curve for Airy beam and the complex parabolic caustic curve for exponentially decaying Airy beam. Further, the special phase and decay factors in the propagating solution of complex amplitude of Airy beams can be directly derived from the phase shifts of light ray cluster along transverse and longitudinal directions. The proposed phase space and ray method can present intuitive comprehension to distinctive propagating characteristics of Airy beams including intensity and phase, without resort to solving wave equation or diffracting integral formula.

Tourette-like syndrome secondary to Kleefstra syndrome 1 with a de novo microdeletion in the EHMT1 gene.

BACKGROUND: Gills de la Tourette syndrome (TS) is a childhood-onset neurodevelopmental disorder manifested by motor and vocal tics. Kleefstra syndrome 1 (KS1), a rare genetic disorder, is caused by haploinsufficiency of the EHMT1 gene and is characterized by intellectual disability (ID), childhood hypotonia, and distinctive facial features. Tourette-like syndrome in KS1 has rarely been reported. CASE PRESENTATION: Here we describe a 7-year-old girl presenting involuntary motor and vocal tics, intellectual disability, childhood hypotonia, and dysmorphic craniofacial appearances, as well as comorbidities including attention deficit-hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), and self-injurious behavior (SIB). The patient's CNV-seq testing revealed a de novo 320-kb deletion in the 9q34.3 region encompassing the EHMT1 gene. CONCLUSIONS: This is the first case reporting Tourette-like syndrome secondary to KS1 with a de novo microdeletion in the EHMT1 gene. Our case suggests TS with ID and facial anomalies indicate a genetic cause and broadens the phenotypic and genotypic spectrum of both TS and KS1.

New Pyrroline Isolated from Antarctic Krill-Derived Actinomycetes Nocardiopsis sp. LX-1 Combining with Molecular Networking.

Antarctic krill (Euphausia superba) of the Euphausiidae family comprise one of the largest biomasses in the world and play a key role in the Antarctic marine ecosystem. However, the study of E. superba-derived microbes and their secondary metabolites has been limited. Chemical investigation of the secondary metabolites of the actinomycetes Nocardiopsis sp. LX-1 (in the family of Nocardiopsaceae), isolated from E. superba, combined with molecular networking, led to the identification of 16 compounds a-p (purple nodes in the molecular network) and the isolation of one new pyrroline, nocarpyrroline A (1), along with 11 known compounds 2-12. The structure of the new compound 1 was elucidated by extensive spectroscopic investigation. Compound 2 exhibited broad-spectrum antibacterial activities against A. hydrophila, D. chrysanthemi, C. terrigena, X. citri pv. malvacearum and antifungal activity against C. albicans in a conventional broth dilution assay. The positive control was ciprofloxacin with the MIC values of <0.024 µM, 0.39 µM, 0.39 µM, 0.39 µM, and 0.20 µM, respectively. Compound 1 and compounds 7, 10, and 11 displayed antifungal activities against F. fujikuroi and D. citri, respectively, in modified agar diffusion test. Prochloraz was used as positive control and showed the inhibition zone radius of 17 mm and 15 mm against F. fujikuroi and D. citri, respectively. All the annotated compounds a-p by molecular networking were first discovered from the genus Nocardiopsis. Nocarpyrroline A (1) features an unprecedented 4,5-dihydro-pyrrole-2-carbonitrile substructure, and it is the first pyrroline isolated from the genus Nocardiopsis. This study further demonstrated the guiding significance of molecular networking in the research of microbial secondary metabolites.

Tetrahedral Framework Nucleic Acids Can Alleviate Taurocholate-Induced Severe Acute Pancreatitis and Its Subsequent Multiorgan Injury in Mice.

Severe acute pancreatitis (SAP) is an inflammatory disease of the pancreas accompanied by tissue injury and necrosis. It not only affects the pancreas but also triggers a systemic inflammatory response that leads to multiorgan failure or even death. Moreover, there is no effective treatment currently that can reverse the disease progression. In this study, tetrahedral framework nucleic acids (tFNAs) were utilized to treat SAP in mice for the first time and proved to be effective in suppressing inflammation and preventing pathological cell death. Serum levels of pancreatitis-related biomarkers witnessed significant changes after tFNAs treatment. Reduction in the expression of certain cytokines involved in local and systemic inflammatory response were observed, together with alteration in proteins related to cell death and apoptosis. Collectively, our results demonstrate that tFNAs could both alleviate SAP and its subsequent multiorgan injury in mice, thus offering a novel and effective option to deal with SAP in the future.

Generation and Use of Glycosyl Radicals under Acidic Conditions: Glycosyl Sulfinates as Precursors.

We herein report a method that enables the generation of glycosyl radicals under highly acidic conditions. Key to the success is the design and use of glycosyl sulfinates as radical precursors, which are bench-stable solids and can be readily prepared from commercial starting materials. This development allows the installation of glycosyl units onto pyridine rings directly by the Minisci reaction. We further demonstrate the utility of this method in the late-stage modification of complex drug molecules, including the anticancer agent camptothecin. Experimental studies provide insight into the reaction mechanism.

Distinct kinetic mechanisms of H3K4 methylation catalyzed by MLL3 and MLL4 core complexes.

The methyltransferases MLL3 and MLL4 primarily catalyze the monomethylation of histone H3 lysine 4 (H3K4) on enhancers to regulate cell-type-specific gene expression and cell fate transition. MLL3 and MLL4 share almost identical binding partners and biochemical activities, but perform specific and nonredundant functions. The features and functions that distinguish MLL3 and MLL4 remain elusive. Here, we characterize the kinetic mechanisms of MLL3 and MLL4 ternary complexes containing the catalytic SET domain from MLL3 or MLL4 (MLL3SET or MLL4SET), the SPRY domain of ASH2L (ASH2LSPRY), and a short fragment of RBBP5 (RBBP5AS-ABM) to search for possible explanations. Steady-state kinetic analyses and inhibition studies reveal that the MLL3 complex catalyzes methylation in a random sequential bi-bi mechanism. In contrast, the MLL4 complex adopts an ordered sequential bi-bi mechanism, in which the cofactor S-adenosylmethionine (AdoMet) binds to the enzyme prior to the H3 peptide, and the methylated H3 peptide dissociates from the enzyme before S-adenosylhomocysteine (AdoHcy) detaches after methylation. Substrate-binding assays using fluorescence polarization (FP) confirm that AdoMet binding is a prerequisite for H3 binding for the MLL4 complex but not for the MLL3 complex. Molecular dynamic simulations reveal that the binding of AdoMet exclusively induces conformational constraints on the AdoMet-binding groove and the H3 substrate-binding pocket of MLL4, therefore stabilizing a specific active conformation to ease entry of the substrate H3. The distinct kinetic mechanisms and conformational plasticities provide important insights into the differential functions of MLL3 and MLL4 and may also guide the development of selective inhibitors targeting MLL3 or MLL4.

D-π-A-Based Trisubstituted Alkenes as Environmentally Sensitive Fluorescent Probes to Detect Lewy Pathologies.

Lewy pathologies, which mainly consist of insoluble α-synuclein (α-syn) aggregates, are the hallmarks of Parkinson's disease and many other neurodegenerative diseases termed "synucleinopathies". Detection of Lewy pathologies with optical methods is of interest for preclinical studies, while the α-syn fluorescent probe is still in great demand. By rational design, we obtained a series of D-π-A-based trisubstituted alkenes with acceptable optical properties and high binding affinities to α-syn fibrils. Among these probes, FPQXN and TQXN-2 exhibited high binding affinities (6 and 8 nM, respectively), significant fluorescence enhancements (17.2- and 26.6-fold, respectively), and satisfying quantum yields (36.5% and 10.4%, respectively), which met the need for the in vitro neuropathological staining of Lewy pathologies in the PD brain sections. In addition, TQXN-2 showed great potential in fluorescent discrimination of Lewy pathologies and Aß plaques. Our research provides flexible tools for in vitro detection of α-syn aggregates and offers new structural frameworks for the further development of α-syn fluorescent probes.

Diabetic oxidative stress-induced telomere damage aggravates periodontal bone loss in periodontitis.

Periodontitis, one of the most common oral complications of diabetes mellitus (DM), causes a reduction in alveolar bone height and loss of alveolar bone mass. It has been shown that DM aggravates the progression of periodontitis, but the mechanism remains inconclusive. The hyperglycemic environment of DM has been proven to generate reactive oxygen species (ROS). Since telomeres, guanine-rich repeats, are highly susceptible to oxidative attack, we speculate that the excessive accumulation of ROS in DM could induce telomere damage resulting in dysfunction of periodontal ligament cells, especially periodontal ligament stem cells (PDLSCs), which reduces the ability of tissue repair and reconstruction in diabetic periodontitis. In this study, our current data revealed that oxidative telomere damage occurred in the periodontal ligaments of diabetic mice. And Micro-CT scans showed reduced alveolar bone height and impaired alveolar bone mass in a diabetic periodontitis model. Next, cultured mouse PDLSCs (mPDLSCs) were treated with the oxidant tert-butyl hydroperoxide (t-BHP) in vitro, as we expected telomere damage was observed and resulted in cellular senescence and dysfunction. Taken together, oxidative stress in DM causes telomere dysfunction and PDLSCs senescence, which influences periodontal bone tissue regeneration and reconstruction and ultimately exacerbates bone loss in periodontitis.

Tfcancer: a manually curated database of transcription factors associated with human cancers.

SUMMARY: Transcription factors (TFs) are critical regulation elements and its dysregulation can lead to a variety of cancers. However, currently, there are no such online resources for large-scale collection, storage and analysis of TF-cancer associations in those cancers. To fill this gap, we present a database called TFcancer (http://lcbb.swjtu.edu.cn/tfcancer/), which contains 3136 experimentally supported associations between 364 TFs and 33 TCGA cancers by manually curating more than 1800 literature. TFcancer mainly concentrates on four aspects: TF expression, molecular alteration, regulatory relationships between TFs and target genes, and biological processes and signaling pathways of TFs in cancers. TFcancer not only provides a user-friendly interface for browsing and searching but also allows flexible data downloading and user data submitting. It is believed that TFcancer is a helpful and valuable resource for researchers who seek to understand the functions and molecular mechanisms of TFs involved in human cancers. AVAILABILITY AND IMPLEMENTATION: The TFcancer are freely available at http://lcbb.swjtu.edu.cn/tfcancer/. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Structural basis for activity regulation of MLL family methyltransferases.

The mixed lineage leukaemia (MLL) family of proteins (including MLL1-MLL4, SET1A and SET1B) specifically methylate histone 3 Lys4, and have pivotal roles in the transcriptional regulation of genes involved in haematopoiesis and development. The methyltransferase activity of MLL1, by itself severely compromised, is stimulated by the three conserved factors WDR5, RBBP5 and ASH2L, which are shared by all MLL family complexes. However, the molecular mechanism of how these factors regulate the activity of MLL proteins still remains poorly understood. Here we show that a minimized human RBBP5-ASH2L heterodimer is the structural unit that interacts with and activates all MLL family histone methyltransferases. Our structural, biochemical and computational analyses reveal a two-step activation mechanism of MLL family proteins. These findings provide unprecedented insights into the common theme and functional plasticity in complex assembly and activity regulation of MLL family methyltransferases, and also suggest a universal regulation mechanism for most histone methyltransferases.

Intraoperative use of low-dose dexmedetomidine for the prevention of emergence agitation following general anaesthesia in elderly patients: a randomized controlled trial.

OBJECTIVE: To clarify the effect of an intraoperative low-dose dexmedetomidine infusion on emergence agitation following general anaesthesia in elderly patients. METHODS: Eighty elderly patients (> 64-years-old) following elective general anaesthesia for radical cancer surgeries were randomly allocated into two groups (n = 40 each): the dexmedetomidine group (Group D) and the normal saline group (Group C). Anaesthesia was maintained with continuous intravenous infusion of dexmedetomidine at - 0.2 µg kg-1 h-1 in Group D, and an equal volume of normal saline (0.5 ml kg-1 h-1) was given in Group C. All patients were observed for 30 min in the post-anaesthesia care unit (PACU), AFPS and NRS were recorded every 2 min, and the total doses of nalbuphine and fentanyl were calculated in the PACU. MAP and HR were recorded at the time of 10 min (T1), 20 min (T2), 30 min (T3) after dexmedetomidine or saline pumping, and before extubation (T4), immediately after extubation (T5), and 5 min after extubation (T6). We also documented some durations, including anaesthesia duration (D1), surgery duration (D2), duration from the end of surgery to extubation (D3), and emergence agitation duration (D4). RESULTS: The MAP in Group C was significantly higher than that in Group D (P < 0.05), and there were no significant changes between the two groups in HR and MAP within each time point and D1, D2, D3, and D4. The incidence of agitation, NRS score and total dose of nalbuphine and fentanyl were all lower in Group D than in Group C (P < 0.05). CONCLUSION: An intraoperative low-dose dexmedetomidine continuous infusion can reduce emergence agitation following general anaesthesia in elderly patients (> 64-years-old), remain stable in terms of haemodynamics, and not lead to delays in anaesthesia recovery time and extubation time.

Tetrahedral Framework Nucleic Acids Induce Immune Tolerance and Prevent the Onset of Type 1 Diabetes.

A failure in immune tolerance leads to autoimmune destruction of insulin-producing ß-cells, leading to type 1 diabetes (T1D). Inhibiting autoreactive T cells and inducing regulatory T cells (Tregs) to re-establish immune tolerance are promising approaches to prevent the onset of T1D. Here, we investigated the ability of tetrahedral framework nucleic acids (tFNAs) to induce immune tolerance and prevent T1D in nonobese diabetic (NOD) mice. In prediabetic NOD mice, tFNAs treatment led to maintenance of normoglycemia and reduced incidence of diabetes. Moreover, the tFNAs (250 nM) treatment preserved the mass and function of ß-cells, increased the frequency of Tregs, and suppressed autoreactive T cells, leading to immune tolerance. Collectively, our results demonstrate that tFNAs treatment aids glycemic control, provides ß-cell protection, and prevents the onset of T1D in NOD mice by immunomodulation. These results highlight the potential of tFNAs for the prevention of autoimmune T1D.