Exploring the activation mechanism of metabotropic glutamate receptor 2.

Homomeric dimerization of metabotropic glutamate receptors (mGlus) is essential for the modulation of their functions and represents a promising avenue for the development of novel therapeutic approaches to address central nervous system diseases. Yet, the scarcity of detailed molecular and energetic data on mGlu2 impedes our in-depth comprehension of their activation process. Here, we employ computational simulation methods to elucidate the activation process and key events associated with the mGlu2, including a detailed analysis of its conformational transitions, the binding of agonists, Gi protein coupling, and the guanosine diphosphate (GDP) release. Our results demonstrate that the activation of mGlu2 is a stepwise process and several energy barriers need to be overcome. Moreover, we also identify the rate-determining step of the mGlu2's transition from the agonist-bound state to its active state. From the perspective of free-energy analysis, we find that the conformational dynamics of mGlu2's subunit follow coupled rather than discrete, independent actions. Asymmetric dimerization is critical for receptor activation. Our calculation results are consistent with the observation of cross-linking and fluorescent-labeled blot experiments, thus illustrating the reliability of our calculations. Besides, we also identify potential key residues in the Gi protein binding position on mGlu2, mGlu2 dimer's TM6-TM6 interface, and Gi α5 helix by the change of energy barriers after mutation. The implications of our findings could lead to a more comprehensive grasp of class C G protein-coupled receptor activation.

Mechanistic study of the transmission pattern of the SARS-CoV-2 omicron variant.

The omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) characterized by 30 mutations in its spike protein, has rapidly spread worldwide since November 2021, significantly exacerbating the ongoing COVID-19 pandemic. In order to investigate the relationship between these mutations and the variant's high transmissibility, we conducted a systematic analysis of the mutational effect on spike-angiotensin-converting enzyme-2 (ACE2) interactions and explored the structural/energy correlation of key mutations, utilizing a reliable coarse-grained model. Our study extended beyond the receptor-binding domain (RBD) of spike trimer through comprehensive modeling of the full-length spike trimer rather than just the RBD. Our free-energy calculation revealed that the enhanced binding affinity between the spike protein and the ACE2 receptor is correlated with the increased structural stability of the isolated spike protein, thus explaining the omicron variant's heightened transmissibility. The conclusion was supported by our experimental analyses involving the expression and purification of the full-length spike trimer. Furthermore, the energy decomposition analysis established those electrostatic interactions make major contributions to this effect. We categorized the mutations into four groups and established an analytical framework that can be employed in studying future mutations. Additionally, our calculations rationalized the reduced affinity of the omicron variant towards most available therapeutic neutralizing antibodies, when compared with the wild type. By providing concrete experimental data and offering a solid explanation, this study contributes to a better understanding of the relationship between theories and observations and lays the foundation for future investigations.

NSUN2/YBX1 promotes the progression of breast cancer by enhancing HGH1 mRNA stability through m5C methylation.

BACKGROUND: RNA m5C methylation has been extensively implicated in the occurrence and development of tumors. As the main methyltransferase, NSUN2 plays a crucial regulatory role across diverse tumor types. However, the precise impact of NSUN2-mediated m5C modification on breast cancer (BC) remains unclear. Our study aims to elucidate the molecular mechanism underlying how NSUN2 regulates the target gene HGH1 (also known as FAM203) through m5C modification, thereby promoting BC progression. Additionally, this study targets at preliminarily clarifying the biological roles of NSUN2 and HGH1 in BC. METHODS: Tumor and adjacent tissues from 5 BC patients were collected, and the m5C modification target HGH1 in BC was screened through RNA sequencing (RNA-seq) and single-base resolution m5C methylation sequencing (RNA-BisSeq). Methylation RNA immunoprecipitation-qPCR (MeRIP-qPCR) and RNA-binding protein immunoprecipitation-qPCR (RIP-qPCR) confirmed that the methylation molecules NSUN2 and YBX1 specifically recognized and bound to HGH1 through m5C modification. In addition, proteomics, co-immunoprecipitation (co-IP), and Ribosome sequencing (Ribo-Seq) were used to explore the biological role of HGH1 in BC. RESULTS: As the main m5C methylation molecule, NSUN2 is abnormally overexpressed in BC and increases the overall level of RNA m5C. Knocking down NSUN2 can inhibit BC progression in vitro or in vivo. Combined RNA-seq and RNA-BisSeq analysis identified HGH1 as a potential target of abnormal m5C modifications. We clarified the mechanism by which NSUN2 regulates HGH1 expression through m5C modification, a process that involves interactions with the YBX1 protein, which collectively impacts mRNA stability and protein synthesis. Furthermore, this study is the first to reveal the binding interaction between HGH1 and the translation elongation factor EEF2, providing a comprehensive understanding of its ability to regulate transcript translation efficiency and protein synthesis in BC cells. CONCLUSIONS: This study preliminarily clarifies the regulatory role of the NSUN2-YBX1-m5C-HGH1 axis from post-transcriptional modification to protein translation, revealing the key role of abnormal RNA m5C modification in BC and suggesting that HGH1 may be a new epigenetic biomarker and potential therapeutic target for BC.

[Role of Fibroblast Growth Factor 7 in Craniomaxillofacial Development]. / æˆçº¤ç»´ç»†èƒžç”Ÿé•¿å› å­7åœ¨é¢ é¢Œé¢å‘è‚²ä¸­çš„ä½œç”¨.

Craniomaxillofacial development involves a series of highly ordered temporal-spatial cellular differentiation processes in which a variety of cell signaling factors, such as fibroblast growth factors, play important regulatory roles. As a classic fibroblast growth factor, fibroblast growth factor 7 (FGF7) serves a wide range of regulatory functions. Previous studies have demonstrated that FGF7 regulates the proliferation and migration of epithelial cells, protects them, and promotes their repair. Furthermore, recent findings indicate that epithelial cells are not the only ones subjected to the broad and powerful regulatory capacity of FGF7. It has potential effects on skeletal system development as well. In addition, FGF7 plays an important role in the development of craniomaxillofacial organs, such as the palate, the eyes, and the teeth. Nonetheless, the role of FGF7 in oral craniomaxillofacial development needs to be further elucidated. In this paper, we summarized the published research on the role of FGF7 in oral craniomaxillofacial development to demonstrate the overall understanding of FGF7 and its potential functions in oral craniomaxillofacial development.

[DNA barcode screening, identification of germplasm resources, and analysis of genetic diversity of Anemarrhena asphodeloides].

Anemarrhena asphodeloides is a common medicinal material used in clinical prescriptions and Chinese patent medicine. In this study, the Illumina platform was used to obtain the chloroplast genome sequences of seven kinds of A. asphodeloides from different areas. The specific DNA barcodes were screened by comparative genomics analysis, and the DNA barcodes were used to identify the germplasm resources and analyze the genetic diversity of A. asphodeloides samples from different areas in China. All the seven chloroplast genomes had a ring structure. The total length was 156 801-156 930 bp, and 113 genes were annotated, including 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. The comparative genomics analysis showed that rps16, trnG-GCC, atpF, rpoB, ycf3, rpl16, ndhF, trnS-GCU＿trnG-GCC, petN-psbM, and ndhF-rpl32 were potential candidates for specific DNA barcodes of A. asphodeloides. In this study, the second intron of ycf3 and atpF intron sequences with a sequence length of 700-800 bp and easy amplification were selected for polymerase chain reaction(PCR) amplification and sequencing of 594 samples from 26 areas. The sequence analysis showed that six and eight haplotypes of ycf3 and atpF sequences could be identified, respectively, and 17 haplotypes could be identified by combined analysis of the two sequences, which were named Hap1-Hap17. The haplotype diversity(H_d), nucleotide diversity(P_i), and genetic distance of A. asphodeloides in 26 populations were 0.68, 0.93×10~(-3), and 0-0.003 1, respectively, indicating that the genetic diversity within the species of A. asphodeloides is rich. The intermediary adjacent network analysis showed that Hap5 was the oldest haplotype, which was mainly distributed in Yixian county of Baoding, Hebei province, Hequ county of Xinzhou, Shanxi province, and Xiangfen county of Linfen, Shanxi province. This study has important guiding significance for the identification of A. asphodeloides species, the protection and development of germplasm resources, and the identification of production areas, and it provides a research basis for further revealing the genetic evolution law of A. asphodeloides.

[The effect of visual-vestibular sensory input consistency on standing stability and electroencephalogram brain network characteristics in the elderly].

Aging is a crucial factor influencing postural stability control and contributing to frequent falls, yet its underlying mechanisms remain incompletely understood. This study aims to explore the effects of aging on postural stability control by comparing differences in postural stability and node strength of electroencephalogram (EEG) brain network between elderly and young people under the conditions of congruent and incongruent visual-vestibular sensory inputs. Eighteen elderly volunteers without neuromuscular disorders and eighteen young individuals participated in the present study. Virtual reality (VR) technology was employed to manipulate visual rotation stimuli (clockwise and counterclockwise), and a horizontal rotating platform was used for vestibular rotation stimuli (clockwise). Based on the directional disparity of sensory input in the horizontal plane, visual-vestibular input consistency was categorized as congruent and incongruent. Postural stability was assessed by the center of pressure (COP) trajectory, and EEG signals were collected and analyzed using directed network analysis to observe EEG brain network node connectivity strength. The results revealed that, under conditions of incongruent visual-vestibular sensory inputs, the elderly exhibited significantly inferior postural stability performance in terms of COP anterior-posterior (Y-axial) sway speed, total path length, anterior-posterior and medial-lateral sample entropy, compared to the young adults. Moreover, the node connectivity strength of visual cortex in the elderly was notably higher, while node connectivity strength of superior temporal cortex was significantly lower than that in the young adults. These findings suggest that the elderly have a heightened reliance on visual information in postural control and an impaired ability to cope with sensory conflicts arising from incongruent visual-vestibular sensory inputs, leading to compromised postural stability. The outcomes of this study hold significant implications for future assessments of balance function in the elder and fall prevention trainings.

[Latest Findings on Ferroptosis and Osteoarthropathy]. / é“æ­»äº¡ä¸Žéª¨å ³èŠ‚ç— çš„ç ”ç©¶æ–°è¿›å±•.

Ferroptosis, a newly-discovered mode of programmed cell death, is closely associated with the development of various diseases throughout the human body, such as tumors of the digestive system, ischemia-reperfusion injury, osteoarthropathy, etc. Therefore, ferroptosis has become a hot research topic in many fields of study in recent years, providing new ideas for the prevention and treatment of relevant diseases. Among them, structural lesions in osteoarthropathies involving articular cartilage, subchondral bone, and synovial tissue have been found to be associated with iron overload, as well as oxidative stress, which suggests that inhibition of ferroptosis in relevant joint tissue cells may have a positive effect in halting the development of osteoarthropathy. Herein, focusing on ferroptosis and osteoarthropathy, we summarized the research developments in mechanisms related to iron metabolism and ferroptosis, analyzed the impact of ferroptosis on the pathogenesis and development of osteoarthropathy, and proposed new ideas for medication therapies of osteoarthropathy, taking into account the latest research findings.

Exploring the Activation Mechanism of the GPR183 Receptor.

The G protein-coupled receptors (GPCRs) play a pivotal role in numerous biological processes as crucial cell membrane receptors. However, the dynamic mechanisms underlying the activation of GPR183, a specific GPCR, remain largely elusive. To address this, we employed computational simulation techniques to elucidate the activation process and key events associated with GPR183, including conformational changes from inactive to active state, binding interactions with the Gi protein complex, and GDP release. Our findings demonstrate that the association between GPR183 and the Gi protein involves the formation of receptor-specific conformations, the gradual proximity of the Gi protein to the binding pocket, and fine adjustments of the protein conformation, ultimately leading to a stable GPR183-Gi complex characterized by a high energy barrier. The presence of Gi protein partially promotes GPR183 activation, which is consistent with the observation of GPCR constitutive activity test experiments, thus illustrating the reliability of our calculations. Moreover, our study suggests the existence of a stable partially activated state preceding complete activation, providing novel avenues for future investigations. In addition, the relevance of GPR183 for various diseases, such as colitis, the response of eosinophils to Mycobacterium tuberculosis infection, antiviral properties, and pulmonary inflammation, has been emphasized, underscoring its therapeutic potential. Consequently, understanding the activation process of GPR183 through molecular dynamic simulations offers valuable kinetic insights that can aid in the development of targeted therapies.

A lysosome-targeted fluorescent probe for fluorescence imaging of hypochlorous acid in living cells and in vivo.

Lysosomes, as crucial acidic organelles in cells, play a significant role in cellular functions. The levels and distribution of hypochlorous acid (HOCl) within lysosomes can profoundly impact their biological functionality. Hence, real-time monitoring of the concentration of HOCl in lysosomes holds paramount importance for further understanding various physiological and pathological processes associated with lysosomes. In this study, we developed a bodipy-based fluorescent probe derived from pyridine and phenyl selenide for the specific detection of HOCl in aqueous solutions. Leveraging the probe's sensitive photoinduced electron transfer effect from phenyl selenide to the fluorophore, the probe exhibited satisfactory high sensitivity (with a limit of detection of 5.2 nM and a response time of 15 s) to hypochlorous acid. Further biological experiments confirmed that the introduction of the pyridine moiety enabled the probe molecule to selectively target lysosomes. Moreover, the probe successfully facilitated real-time monitoring of HOCl in cell models stimulated by N-acetylcysteine (NAC) and lipopolysaccharide (LPS), as well as in a normal zebrafish model. This provides a universal method for dynamically sensing HOCl in lysosomes.

Bodipy-Based highly sensitive hydrogen sulfide fluorescent probe and its fluorescence imaging in cells and zebrafish.

Hydrogen sulfide (H2S) is a crucial endogenous gasotransmitter that plays a role in various physiological and pathological processes. Therefore, accurate and rapid monitoring of H2S in organisms is highly significant for understanding the underlying pathological mechanisms and facilitating early diagnosis of related diseases. In this study, we developed a novel fluorescent probe, B-CHO-NO2, based on a bodipy fluorophore, which exhibits excellent sensitivity and selectivity towards H2S. The design of the probe exploits the nucleophilicity of H2S by introducing a formyl group as the ortho-participating moiety, significantly enhancing the reaction rate with H2S. In cellular and zebrafish models, the probe B-CHO-NO2 successfully achieved fluorescence imaging of endogenous and exogenous H2S. The development of probe B-CHO-NO2 provides a powerful tool for biological studies of H2S and diagnosis of related diseases.

Corrigendum: A novel model based on necroptosis to assess progression for polycystic ovary syndrome and identification of potential therapeutic drugs.

[This corrects the article DOI: 10.3389/fendo.2023.1193992.].

Determination of Maximum Tolerable Cold Ischemia Time in a Mouse Model of Cervical Heterotopic Uterus Transplantation.

BACKGROUND: Uterus transplantation (UTx) is an emerging treatment for uterine factor infertility. Determining the maximum tolerable cold ischemia time is crucial for successful UTx. However, the limit for cold ischemia in the uterus is unclear. This study aimed to examine cold ischemia's effects on mouse uteri and identify the maximum cold ischemia duration that uteri can endure. METHODS: We systematically assessed the tolerance of mouse uteri to extended cold ischemia, 24 h, 36 h, and 48 h, using the cervical heterotopic UTx model. Multiple indicators were used to evaluate ischemia-reperfusion injury, including reperfusion duration, macroscopic examination, oxidative stress, inflammation, and histopathology. The function of transplants was evaluated through estrous cycle monitoring and embryo transfer. RESULTS: Mouse uteri subjected to 48 h of cold ischemia exhibited significant delays and insufficiencies in reperfusion, substantial tissue necrosis, and loss of the estrous cycle. Conversely, uteri that underwent cold ischemia within 36 h showed long survival, regular estrous cycles, and fertility. CONCLUSIONS: Our study demonstrated that mouse uteri can endure at least 36 h of cold ischemia, extending the known limits for cold ischemia and providing a pivotal reference for research on the prevention and treatment of cold ischemic injury in UTx.

An isotropic zero thermal expansion alloy with super-high toughness.

Zero thermal expansion (ZTE) alloys with high mechanical response are crucial for their practical usage. Yet, unifying the ZTE behavior and mechanical response in one material is a grand obstacle, especially in multicomponent ZTE alloys. Herein, we report a near isotropic zero thermal expansion (αl = 1.10 × 10-6 K-1, 260-310 K) in the natural heterogeneous LaFe54Co3.5Si3.35 alloy, which exhibits a super-high toughness of 277.8 ± 14.7 J cm-3. Chemical partition, in the dual-phase structure, assumes the role of not only modulating thermal expansion through magnetic interaction but also enhancing mechanical properties via interface bonding. The comprehensive analysis reveals that the hierarchically synergistic enhancement among lattice, phase interface, and heterogeneous structure is significant for strong toughness. Our findings pave the way to tailor thermal expansion and obtain prominent mechanical properties in multicomponent alloys, which is essential to ultra-stable functional materials.

A recurrence-predictive model based on eight genes and tumor mutational burden/microsatellite instability status in Stage II/III colorectal cancer.

BACKGROUND: Although adjuvant chemotherapy (ACT) is widely used to treat patients with Stage II/III colorectal cancer (CRC), administering ACT to specific patients remains a challenge. The decision to ACT requires an accurate assessment of recurrence risk and absolute treatment benefit. However, the traditional TNM staging system does not accurately assess a patient's individual risk of recurrence. METHODS: To identify recurrence risk-related genetic factors for Stage II/III CRC patients after radical surgery, we conducted an analysis of whole-exome sequencing of 47 patients with Stage II/III CRC who underwent radical surgery at five institutions. Patients were grouped into non-recurrence group (NR, n = 24, recurrence-free survival [RFS] > 5 years) and recurrence group (R, n = 23, RFS <2 years). The TCGA-COAD/READ cohort was employed as the validation dataset. RESULTS: A recurrence-predictive model (G8plus score) based on eight gene (CUL9, PCDHA12, HECTD3, DCX, SMARCA2, FAM193A, AATK, and SORCS2) mutations and tumor mutation burden/microsatellite instability (TMB/MSI) status was constructed, with 97.87% accuracy in our data and 100% negative predictive value in the TCGA-COAD/READ cohort. For the TCGA-COAD/READ cohort, the G8plus-high group had better RFS (HR = 0.22, p = 0.024); the G8plus-high tumors had significantly more infiltrated immune cell types, higher tertiary lymphoid structure signature scores, and higher immunological signature scores. The G8plus score was also a predict biomarker for immunotherapeutic in advanced CRC in the PUCH cohort. CONCLUSIONS: In conclusion, the G8plus score is a powerful biomarker for predicting the risk of recurrence in patients with stage II/III CRC. It can be used to stratify patients who benefit from ACT and immunotherapy.