Targeting KRAS Mutant Cancers with a Covalent G12C-Specific Inhibitor.

KRASG12C was recently identified to be potentially druggable by allele-specific covalent targeting of Cys-12 in vicinity to an inducible allosteric switch II pocket (S-IIP). Success of this approach requires active cycling of KRASG12C between its active-GTP and inactive-GDP conformations as accessibility of the S-IIP is restricted only to the GDP-bound state. This strategy proved feasible for inhibiting mutant KRAS in vitro; however, it is uncertain whether this approach would translate to in vivo. Here, we describe structure-based design and identification of ARS-1620, a covalent compound with high potency and selectivity for KRASG12C. ARS-1620 achieves rapid and sustained in vivo target occupancy to induce tumor regression. We use ARS-1620 to dissect oncogenic KRAS dependency and demonstrate that monolayer culture formats significantly underestimate KRAS dependency in vivo. This study provides in vivo evidence that mutant KRAS can be selectively targeted and reveals ARS-1620 as representing a new generation of KRASG12C-specific inhibitors with promising therapeutic potential.

Thermodynamic properties and enhancement of diamagnetism in nitrogen doped lutetium hydride synthesized at high pressure.

Nitrogen doped lutetium hydride has drawn global attention in the pursuit of room-temperature superconductivity near ambient pressure and temperature. However, variable synthesis techniques and uncertainty surrounding nitrogen concentration have contributed to extensive debate within the scientific community about this material and its properties. We used a solid-state approach to synthesize nitrogen doped lutetium hydride at high pressure and temperature (HPT) and analyzed the residual starting materials to determine its nitrogen content. High temperature oxide melt solution calorimetry determined the formation enthalpy of LuH1.96N0.02 (LHN) from LuH2 and LuN to be -28.4 ± 11.4 kJ/mol. Magnetic measurements indicated diamagnetism which increased with nitrogen content. Ambient pressure conductivity measurements observed metallic behavior from 5 to 350 K, and the constant and parabolic magnetoresistance changed with increasing temperature. High pressure conductivity measurements revealed that LHN does not exhibit superconductivity up to 26.6 GPa. We compressed LHN in a diamond anvil cell to 13.7 GPa and measured the Raman signal at each step, with no evidence of any phase transition. Despite the absence of superconductivity, a color change from blue to purple to red was observed with increasing pressure. Thus, our findings confirm the thermodynamic stability of LHN, do not support superconductivity, and provide insights into the origins of its diamagnetism.

The codriven assembly of molecular metalla-links ([Formula: see text], [Formula: see text]) and metalla-knots ([Formula: see text], [Formula: see text]) via coordination and noncovalent interactions.

Although mechanically interlocked molecules (MIMs) display unique properties and functions associated with their intricate connectivity, limited assembly strategies are available for their synthesis. Herein, we presented a synergistic assembly strategy based on coordination and noncovalent interactions (π-π stacking and CH⋯π interactions) to selectively synthesize molecular closed three-link chains ([Formula: see text] links), highly entangled figure-eight knots ([Formula: see text] knots), trefoil knot ([Formula: see text] knot), and Borromean ring ([Formula: see text] link). [Formula: see text] links can be created by the strategic assembly of nonlinear multicurved ligands incorporating a furan or phenyl group with the long binuclear half-sandwich organometallic Cp*RhIII (Cp* = η5-pentamethylcyclopentadienyl) clip. However, utilizing much shorter binuclear Cp*RhIII units for union with the 2,6-naphthyl-containing ligand led to a [Formula: see text] knot because of the increased π-π stacking interactions between four consecutive stacked layers and CH⋯π interactions. Weakening such π-π stacking interactions resulted in a [Formula: see text] knot. The universality of this synergistic assembly strategy for building [Formula: see text] knots was verified by utilizing a 1,5-naphthyl-containing ligand. Quantitative conversion between the [Formula: see text] knot and the simple macrocycle species was accomplished by adjusting the concentrations monitored by NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Furthermore, increasing the stiff π-conjugated area of the binuclear unit afforded molecular Borromean ring, and this topology is a topological isomer of the [Formula: see text] link. These artificial metalla-links and metalla-knots were confirmed by single-crystal X-ray diffraction, NMR and ESI-MS. The results offer a potent strategy for building higher-order MIMs and emphasize the critical role that noncovalent interactions play in creating sophisticated topologies.

AMPK Attenuation of ß-Adrenergic Receptor-Induced Cardiac Injury via Phosphorylation of ß-Arrestin-1-ser330.

BACKGROUND: ß-adrenergic receptor (ß-AR) overactivation is a major pathological cue associated with cardiac injury and diseases. AMPK (AMP-activated protein kinase), a conserved energy sensor, regulates energy metabolism and is cardioprotective. However, whether AMPK exerts cardioprotective effects via regulating the signaling pathway downstream of ß-AR remains unclear. METHODS: Using immunoprecipitation, mass spectrometry, site-specific mutation, in vitro kinase assay, and in vivo animal studies, we determined whether AMPK phosphorylates ß-arrestin-1 at serine (Ser) 330. Wild-type mice and mice with site-specific mutagenesis (S330A knock-in [KI]/S330D KI) were subcutaneously injected with the ß-AR agonist isoproterenol (5 mg/kg) to evaluate the causality between ß-adrenergic insult and ß-arrestin-1 Ser330 phosphorylation. Cardiac transcriptomics was used to identify changes in gene expression from ß-arrestin-1-S330A/S330D mutation and ß-adrenergic insult. RESULTS: Metformin could decrease cAMP/PKA (protein kinase A) signaling induced by isoproterenol. AMPK bound to ß-arrestin-1 and phosphorylated Ser330 with the highest phosphorylated mass spectrometry score. AMPK activation promoted ß-arrestin-1 Ser330 phosphorylation in vitro and in vivo. Neonatal mouse cardiomyocytes overexpressing ß-arrestin-1-S330D (active form) inhibited the ß-AR/cAMP/PKA axis by increasing PDE (phosphodiesterase) 4 expression and activity. Cardiac transcriptomics revealed that the differentially expressed genes between isoproterenol-treated S330A KI and S330D KI mice were mainly involved in immune processes and inflammatory response. ß-arrestin-1 Ser330 phosphorylation inhibited isoproterenol-induced reactive oxygen species production and NLRP3 (NOD-like receptor protein 3) inflammasome activation in neonatal mouse cardiomyocytes. In S330D KI mice, the ß-AR-activated cAMP/PKA pathways were attenuated, leading to repressed inflammasome activation, reduced expression of proinflammatory cytokines, and mitigated macrophage infiltration. Compared with S330A KI mice, S330D KI mice showed diminished cardiac fibrosis and improved cardiac function upon isoproterenol exposure. However, the cardiac protection exerted by AMPK was abolished in S330A KI mice. CONCLUSIONS: AMPK phosphorylation of ß-arrestin-1 Ser330 potentiated PDE4 expression and activity, thereby inhibiting ß-AR/cAMP/PKA activation. Subsequently, ß-arrestin-1 Ser330 phosphorylation blocks ß-AR-induced cardiac inflammasome activation and remodeling.

Viscosity of Ionic Liquids: Theories and Models.

Ionic liquids (ILs) offer a wide range of promising applications due to their unique and designable properties compared to conventional solvents. Further development and application of ILs require correlating/predicting their pressure-viscosity-temperature behavior. In this review, we firstly introduce methods for calculation of thermodynamic inputs of viscosity models. Next, we introduce theories, theoretical and semi-empirical models coupling various theories with EoSs or activity coefficient models, and empirical and phenomenological models for viscosity of pure ILs and IL-related mixtures. Our modelling description is followed immediately by model application and performance. Then, we propose simple predictive equations for viscosity of IL-related mixtures and systematically compare performances of the above-mentioned theories and models. In concluding remarks, we recommend robust predictive models for viscosity at atmospheric pressure as well as proper and consistent theories and models for P-η-T behavior. The work that still remains to be done to obtain the desired theories and models for viscosity of ILs and IL-related mixtures is also presented. The present review is structured from pure ILs to IL-related mixtures and aims to summarize and quantitatively discuss the recent advances in theoretical and empirical modelling of viscosity of ILs and IL-related mixtures.

Riding apoptotic bodies for cell-cell transmission by African swine fever virus.

African swine fever virus (ASFV), a devastating pathogen to the worldwide swine industry, mainly targets macrophage/monocyte lineage, but how the virus enters host cells has remained unclear. Here, we report that ASFV utilizes apoptotic bodies (ApoBDs) for infection and cell-cell transmission. We show that ASFV induces cell apoptosis of primary porcine alveolar macrophages (PAMs) at the late stage of infection to productively shed ApoBDs that are subsequently swallowed by neighboring PAMs to initiate a secondary infection as evidenced by electron microscopy and live-cell imaging. Interestingly, the virions loaded within ApoBDs are exclusively single-enveloped particles that are devoid of the outer layer of membrane and represent a predominant form produced during late infection. The in vitro purified ApoBD vesicles are capable of mediating virus infection of naive PAMs, but the transmission can be significantly inhibited by blocking the "eat-me" signal phosphatidyserine on the surface of ApoBDs via Annexin V or the efferocytosis receptor TIM4 on the recipient PAMs via anti-TIM4 antibody, whereas overexpression of TIM4 enhances virus infection. The same treatment however did not affect the infection by intracellular viruses. Importantly, the swine sera to ASFV exert no effect on the ApoBD-mediated transmission but can partially act on the virions lacking the outer layer of membrane. Thus, ASFV has evolved to hijack a normal cellular pathway for cell-cell spread to evade host responses.

Intercalant-induced V t2g orbital occupation in vanadium oxide cathode toward fast-charging aqueous zinc-ion batteries.

Intercalation-type layered oxides have been widely explored as cathode materials for aqueous zinc-ion batteries (ZIBs). Although high-rate capability has been achieved based on the pillar effect of various intercalants for widening interlayer space, an in-depth understanding of atomic orbital variations induced by intercalants is still unknown. Herein, we design an NH4+-intercalated vanadium oxide (NH4+-V2O5) for high-rate ZIBs, together with deeply investigating the role of the intercalant in terms of atomic orbital. Besides extended layer spacing, our X-ray spectroscopies reveal that the insertion of NH4+ could promote electron transition to 3dxy state of V t2g orbital in V2O5, which significantly accelerates the electron transfer and Zn-ion migration, further verified by DFT calculations. As results, the NH4+-V2O5 electrode delivers a high capacity of 430.0 mA h g-1 at 0.1 A g-1, especially excellent rate capability (101.0 mA h g-1 at 200 C), enabling fast charging within 18 s. Moreover, the reversible V t2g orbital and lattice space variation during cycling are found via ex-situ soft X-ray absorption spectrum and in-situ synchrotron radiation X-ray diffraction, respectively. This work provides an insight at orbital level in advanced cathode materials.

RABV induces biphasic actin cytoskeletal rearrangement through Rac1 activity modulation.

Rabies virus (RABV) is highly lethal and triggers severe neurological symptoms. The neuropathogenic mechanism remains poorly understood. Ras-related C3 botulinum toxin substrate 1 (Rac1) is a Rho-GTPase that is involved in actin remodeling and has been reported to be closely associated with neuronal dysfunction. In this study, by means of a combination of pharmacological inhibitors, small interfering RNA, and specific dominant-negatives, we characterize the crucial roles of dynamic actin and the regulatory function of Rac1 in RABV infection, dominantly in the viral entry phase. The data show that the RABV phosphoprotein interacts with Rac1. RABV phosphoprotein suppress Rac1 activity and impedes downstream Pak1-Limk1-Cofilin1 signaling, leading to the disruption of F-actin-based structure formation. In early viral infection, the EGFR-Rac1-signaling pathway undergoes a biphasic change, which is first upregulated and subsequently downregulated, corresponding to the RABV entry-induced remodeling pattern of F-actin. Taken together, our findings demonstrate for the first time the role played by the Rac1 signaling pathway in RABV infection and may provide a clue for an explanation for the etiology of rabies neurological pathogenesis.IMPORTANCEThough neuronal dysfunction is predominant in fatal rabies, the detailed mechanism by which rabies virus (RABV) infection causes neurological symptoms remains in question. The actin cytoskeleton is involved in numerous viruses infection and plays a crucial role in maintaining neurological function. The cytoskeletal disruption is closely associated with abnormal nervous symptoms and induces neurogenic diseases. In this study, we show that RABV infection led to the rearrangement of the cytoskeleton as well as the biphasic kinetics of the Rac1 signal transduction. These results help elucidate the mechanism that causes the aberrant neuronal processes by RABV infection and may shed light on therapeutic development aimed at ameliorating neurological disorders.

The 5'UTR of porcine reproductive and respiratory syndrome virus strain JXwn06 harbors a uORF that regulates cellular inflammation.

The 5' untranslated region (5'UTR) of many positive-stranded RNA viruses contain functional regulatory sequences. Here, we show that the porcine reproductive and respiratory syndrome virus (PRRSV), a member of arteriviruses, harbors small upstream open reading frames (uORFs) in its 5'UTR. Bioinformatics analysis shows that this feature is relatively well conserved among PRRSV strains and Arteriviridae. We also identified a uORF, namely uORF2, in the PRRSV strain JXwn06, that possesses translational activity and exerts a suppressive effect on the expression of the primary ORF evidenced by in vitro reporter assays. We tested its importance via reverse genetics by introducing a point mutation into the PRRSV infectious cDNA clone to inactivate the start codon of uORF2. The recovered mutant virus Mut2 surprisingly replicated to the same level as the wild-type virus (WT), but induced a higher level of inflammatory cytokines (e.g., TNF-α, IL-1ß, and IL-6) both in vitro and in animal experiments, correlating well with more severe lung injury and higher death rate. In line with this, over-expression of uORF2 in transfected cells significantly inhibited poly(I:C)-induced expression of inflammatory cytokines. Together, our data support the idea that uORF2 encodes a novel, functional regulator of PRRSV virulence despite of its short size. IMPORTANCE: PRRSV has remained a major challenge to the world swine industry, but we still do not know much about its biology and pathogenesis. Here, we provide evidence to show that the 5'UTR of PRRSV strain JXwn06 harbors a functional uORF that has the coding capacity and regulates induction of inflammation as demonstrated by in vitro assays and animal experiment. The findings reveal a novel viral factor that regulates cellular inflammation and provide insight into the understanding of PRRSV pathogenesis.

MdbHLH160 is stabilized via reduced MdBT2-mediated degradation to promote MdSOD1 and MdDREB2A-like expression for apple drought tolerance.

Drought stress is a key environmental factor limiting the productivity, quality, and geographic distribution of crops worldwide. Abscisic acid (ABA) plays an important role in plant drought stress responses, but the molecular mechanisms remain unclear. Here, we report an ABA-responsive bHLH transcription factor, MdbHLH160, which promotes drought tolerance in Arabidopsis (Arabidopsis thaliana) and apple (Malus domestica). Under drought conditions, MdbHLH160 is directly bound to the MdSOD1 (superoxide dismutase 1) promoter and activated its transcription, thereby triggering reactive oxygen species (ROS) scavenging and enhancing apple drought tolerance. MdbHLH160 also promoted MdSOD1 enzyme activity and accumulation in the nucleus through direct protein interactions, thus inhibiting excessive nuclear ROS levels. Moreover, MdbHLH160 directly upregulated the expression of MdDREB2A-like, a DREB (dehydration-responsive element binding factor) family gene that promotes apple drought tolerance. Protein degradation and ubiquitination assays showed that drought and ABA treatment stabilized MdbHLH160. The BTB protein MdBT2 was identified as an MdbHLH160-interacting protein that promoted MdbHLH160 ubiquitination and degradation, and ABA treatment substantially inhibited this process. Overall, our findings provide insights into the molecular mechanisms of ABA-modulated drought tolerance at both the transcriptional and post-translational levels via the ABA-MdBT2-MdbHLH160-MdSOD1/MdDREB2A-like cascade.

Structural and functional abnormalities in first-episode drug-naïve pediatric idiopathic generalized epilepsy.

The aim of this study was to investigate brain structure and corresponding static and dynamic functional connectivity (sFC & dFC) abnormalities in untreated, first-episode pediatric idiopathic generalized epilepsy (IGE), with the goal of better understanding the underlying pathological mechanisms of IGE. Thirty-one children with IGE and 31 age-matched healthy controls (HC) were recruited. Structural magnetic resonance imaging (sMRI) data were acquired, and voxel-based morphometry (VBM) analysis were performed to reveal abnormal gray matter volume (GMV). Moreover, sFC and dFC analyses were conducted using the brain areas exhibiting abnormal GMV as seed regions to explore abnormal functional couplings. Compared to HC, the IGE group exhibited increased GMV in left middle cingulate cortex (MCC) and right parahippocampus (ParaHipp). In addition, the analyses of dFC and sFC with MCC and ParaHipp as seeds revealed more extensive functional connectivity (FC) changes in dFC. Notably, the structurally and functionally abnormal brain areas were primarily localized in the default mode network (DMN). However, our study did not find any significant associations between these altered neuroimaging measurements and clinical outcomes. This study uncovered microstructural changes as well as corresponding sFC and dFC changes in patients with new-onset, untreated pediatric IGE. The affected brain regions were primarily located within the DMN, highlighting the DMN's crucial role in the development of pediatric IGE.

Superantigen-fused T cell engagers for tumor antigen-mediated robust T cell activation and tumor cell killing.

Inadequate T cell activation has severely limited the success of T cell engager (TCE) therapy, especially in solid tumors. Enhancing T cell activity while maintaining the tumor specificity of TCEs is the key to improving their clinical efficacy. However, currently, there needs to be more effective strategies in clinical practice. Here, we design novel superantigen-fused TCEs that display robust tumor antigen-mediated T cell activation effects. These innovative drugs are not only armed with the powerful T cell activation ability of superantigens but also retain the dependence of TCEs on tumor antigens, realizing the ingenious combination of the advantages of two existing drugs. Superantigen-fused TCEs have been preliminarily proven to have good (>30-fold more potent) and specific (>25-fold more potent) antitumor activity in vitro and in vivo. Surprisingly, they can also induce the activation of T cell chemotaxis signals, which may promote T cell infiltration and further provide an additional guarantee for improving TCE efficacy in solid tumors. Overall, this proof-of-concept provides a potential strategy for improving the clinical efficacy of TCEs.

Disruption of pulmonary microvascular endothelial barrier by dysregulated claudin-8 and claudin-4: uncovered mechanisms in porcine reproductive and respiratory syndrome virus infection.

The pulmonary endothelium is a dynamic and metabolically active monolayer of endothelial cells. Dysfunction of the pulmonary endothelial barrier plays a crucial role in the acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), frequently observed in the context of viral pneumonia. Dysregulation of tight junction proteins can lead to the disruption of the endothelial barrier and subsequent leakage. Here, the highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) served as an ideal model for studying ALI and ARDS. The alveolar lavage fluid of pigs infected with HP-PRRSV, and the supernatant of HP-PRRSV infected pulmonary alveolar macrophages were respectively collected to treat the pulmonary microvascular endothelial cells (PMVECs) in Transwell culture system to explore the mechanism of pulmonary microvascular endothelial barrier leakage caused by viral infection. Cytokine screening, addition and blocking experiments revealed that proinflammatory cytokines IL-1ß and TNF-α, secreted by HP-PRRSV-infected macrophages, disrupt the pulmonary microvascular endothelial barrier by downregulating claudin-8 and upregulating claudin-4 synergistically. Additionally, three transcription factors interleukin enhancer binding factor 2 (ILF2), general transcription factor III C subunit 2 (GTF3C2), and thyroid hormone receptor-associated protein 3 (THRAP3), were identified to accumulate in the nucleus of PMVECs, regulating the transcription of claudin-8 and claudin-4. Meanwhile, the upregulation of ssc-miR-185 was found to suppress claudin-8 expression via post-transcriptional inhibition. This study not only reveals the molecular mechanisms by which HP-PRRSV infection causes endothelial barrier leakage in acute lung injury, but also provides novel insights into the function and regulation of tight junctions in vascular homeostasis.

Viral evasion of PKR restriction by reprogramming cellular stress granules.

Protein kinase R (PKR) is a critical host restriction factor against invading viral pathogens. However, this molecule is inactivated in the cells infected with porcine reproductive and respiratory syndrome virus (PRRSV), an economically devastating pathogen to the world swine industry. Here, we report that this event is to suppress cellular inflammation and is mediated by the viral replicase protein nsp1ß. We show that nsp1ß is a stress-responsive protein, enters virus-induced stress granules (SGs) during infection, and repurposes SGs into a proviral platform, where it co-opts the SG core component G3BP1 to interact with PKR in a regulated manner. RNA interference silencing of G3BP1 or mutation of specific nsp1ß residues (VS19GG) can abolish the antagonization of PKR activation. The viral mutant carrying the corresponding mutations induces elevated level of PKR phosphorylation and pronounced production of inflammatory cytokines (e.g., tumor necrosis factor-α, interleukin [IL]-6, and IL-8), whereas small-interfering RNA knockdown of PKR or treatment with C16, a PKR inhibitor, blocks this effect. Thus, PRRSV has evolved a unique strategy to evade PKR restriction to suppress host inflammatory responses.

NAMPT regulates mitochondria function and lipid metabolism during porcine oocyte maturation.

Oocyte maturation defect can lead to maternal reproduction disorder. NAMPT is a rate-limiting enzyme in mammalian NAD+ biosynthesis pathway, which can regulate a variety of cellular metabolic processes including glucose metabolism and DNA damage repair. However, the function of NAMPT in porcine oocytes remains unknown. In this study, we showed that NAMPT involved into multiple cellular events during oocyte maturation. NAMPT expressed during all stages of porcine oocyte meiosis, and inhibition of NAMPT activity caused the cumulus expansion and polar body extrusion defects. Mitochondrial dysfunction was observed in NAMPT-deficient porcine oocytes, which showed decreased membrane potential, ATP and mitochondrial DNA content, increased oxidative stress level and apoptosis. We also found that NAMPT was essential for spindle organization and chromosome arrangement based on Ac-tubulin. Moreover, lack of NAMPT activity caused the increase of lipid droplet and affected the imbalance of lipogenesis and lipolysis. In conclusion, our study indicated that lack of NAMPT activity affected porcine oocyte maturation through its effects on mitochondria function, spindle assembly and lipid metabolism.

Correlating π-π Stacking of Aromatic Diammoniums with Stability and Dimensional Reduction of Dion-Jacobson 2D Perovskites.

Dion-Jacobson (DJ) phase 2D perovskites with various aromatic diammonium cations, potentially possessing high stability, have been developed for optoelectronics. However, their stability does not meet initial expectations, and some of them even easily degrade into lower-dimensional structures. Underlying the stability mechanism and dimensional reduction of these DJ 2D perovskites remains elusive. Herein, we report that π-π stacking intensity between aromatic cations determines structural stability and dimensional variation of DJ 2D perovskites by investigating nine benzene diammoniums (BDAs)-derived low-dimensional perovskites. The BDAs without intermolecular π-π stacking form stable DJ 2D perovskites, while those showing strong π-π stacking tend to generate 1D and 0D architectures. Furthermore, the π-π stacking intensity highly relies on molecular symmetry and electrostatic potential of BDAs; namely, asymmetry and small dipole moment facilitate alleviating the π-π stacking, leading to the formation of DJ 2D perovskites and vice versa. Our findings establish the relationship of aromatic diammonium structure-π-π stacking interaction-perovskite dimensionality, which can guide the design of stable DJ 2D perovskites and the manipulation of perovskite dimensionality for various optoelectronic applications.

The Topological Transformation of Trefoil Knots to Solomon Links via Diels-Alder Click Reaction.

The quest for more efficient, user-friendly, and less wasteful topological transformations remains a significant challenge in the realm of postassembly modifications. In this article, high yields of two molecular trefoil knots (Rh-1, Ir-1) were obtained using ligand 3,6-bis(3-(pyridin-4-yl)phenyl)-1,2,4,5-tetrazine (L1) with reactive tetrazine units and binuclear half-sandwich organometallic units [Cp*2M2(µ-TPPHZ)(OTf)2](OTf)2 (Rh-B, M = RhIII; Ir-B, M = IrIII). 2,5-Norbornadiene was used as an inducer of the Diels-Alder click reaction to modulate rapidly and efficiently the transformation of Trefoil knots to Solomon links. However, the key to achieving this topological structural change is the subtle increase in site steric of the pyridazine fragments (L2), which allows the molecular structures to spread and bend in three-dimensional space, as confirmed by single-crystal X-ray diffraction, ESI-TOF/MS, elementary analysis and detailed solution-state NMR techniques.

The Topological Transformation of 41 Knot to 412 Link through Supramolecular Fusion.

Realizing topological transformation through supramolecular fusion is particularly challenging, as the self-assembly of disparate components often results in the orthogonal assembly of building blocks into distinct structures rather than the formation of a heteroleptic architecture. This study introduces a topological transformation, transitioning from a figure-eight knot (41 knot) to a Solomon link (412 link) through a supramolecular fusion process. By employing two structurally similar amino acid ligands (L1 and L3) of varying lengths as bridge ligands, we obtained figure-eight knot 1 and a molecular tweezer-like compound 3 when individually complexed with binuclear Cp*Rh acceptor B1. Our results revealed that subtle modifications to bridge ligands can lead to dramatic changes in their structures and recognition properties. Moreover, we successfully achieved the targeted formation of a heteroleptic Solomon link 4 by blending figure-eight knot 1 and compound 3 in a 1:1 ratio without the need for templates. This procedure effortlessly converted the 41 knot into a 412 link, thus marking a significant advancement in the topological transformation. This work not only marks the construction of the first heteroleptic Solomon link comprising two distinct metallamacrocycles but also demonstrates a process of supramolecular fusion-based topological transformation involving three distinct topological structures.

ALA Promotes Sucrose Accumulation in Early Peach Fruit by Regulating SPS Activity.

5-Aminolevulinic acid (ALA), as a novel plant growth regulator, is a critical precursor for the biosynthesis of porphyrin compounds in all organisms. Many studies have reported that exogenous ALA treatment could improve fruit sweetness. However, the mechanism by which ALA promotes the increase in sugar content in fruit remains unclear. In this study, we found that ALA significantly promoted sucrose accumulation and SPS (sucrose phosphate synthase) activity in peach fruit. At 14, 28, 42, 50 and 60 days after ALA treatment, sucrose content of fruit was increased by 23%, 43%, 37%, 40% and 16%, respectively, compared with control treatment, and SPS enzyme activity was increased by 21%, 28%, 47%, 37% and 29%, respectively. Correlation analysis showed that the sucrose content of peach fruit under ALA treatment was significantly positively correlated with SPS activity. Subsequently, bioinformatics was used to identify SPS gene family members in peach fruit, and it was found that there were four members of the PpSPS gene family, distributed on chromosomes 1, 7 and 8, named PpSPS1, PpSPS2, PpSPS3 and PpSPS4, respectively. The results of qRT-PCR showed that PpSPS2 and PpSPS3 were highly expressed in response to ALA during fruit development, and the expression of PpSPS2 was positively correlated with SPS activity and sucrose accumulation in peach fruit. The results of tobacco subcellular localization showed that PpSPS2 was mainly distributed in the cytoplasm and nucleus, while PpSPS3 was mainly distributed in the nucleus. The results of this study will lay the foundation for further study on the functions of PpSPS and the regulation of sugar metabolism during the development and ripening of peach fruit by ALA.

hP-MSCs attenuate severe acute pancreatitis in mice via inhibiting NLRP3 inflammasome-mediated acinar cell pyroptosis.

BACKGROUND: Severe acute pancreatitis (SAP) is a serious gastrointestinal disease that is facilitated by pancreatic acinar cell death. The protective role of human placental mesenchymal stem cells (hP-MSCs) in SAP has been demonstrated in our previous studies. However, the underlying mechanisms of this therapy remain unclear. Herein, we investigated the regularity of acinar cell pyroptosis during SAP and investigated whether the protective effect of hP-MSCs was associated with the inhibition of acinar cell pyroptosis. METHODS: A mouse model of SAP was established by the retrograde injection of sodium taurocholate (NaTC) solution in the pancreatic duct. For the hP-MSCs group, hP-MSCs were injected via the tail vein and were monitored in vivo. Transmission electron microscopy (TEM) was used to observe the pyroptosis-associated ultramorphology of acinar cells. Immunofluorescence and Western blotting were subsequently used to assess the localization and expression of pyroptosis-associated proteins in acinar cells. Systemic inflammation and local injury-associated parameters were evaluated. RESULTS: Acinar cell pyroptosis was observed during SAP, and the expression of pyroptosis-associated proteins initially increased, peaked at 24 h, and subsequently showed a decreasing trend. hP-MSCs effectively attenuated systemic inflammation and local injury in the SAP model mice. Importantly, hP-MSCs decreased the expression of pyroptosis-associated proteins and the activity of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in acinar cells. CONCLUSIONS: Our study demonstrates the regularity and important role of acinar cell pyroptosis during SAP. hP-MSCs attenuate inflammation and inhibit acinar cell pyroptosis via suppressing NLRP3 inflammasome activation, thereby exerting a protective effect against SAP.