Modulation of Protein-Interaction States through the Cell Cycle.

Global profiling of protein expression through the cell cycle has revealed subsets of periodically expressed proteins. However, expression levels alone only give a partial view of the biochemical processes determining cellular events. Using a proteome-wide implementation of the cellular thermal shift assay (CETSA) to study specific cell-cycle phases, we uncover changes of interaction states for more than 750 proteins during the cell cycle. Notably, many protein complexes are modulated in specific cell-cycle phases, reflecting their roles in processes such as DNA replication, chromatin remodeling, transcription, translation, and disintegration of the nuclear envelope. Surprisingly, only small differences in the interaction states were seen between the G1 and the G2 phase, suggesting similar hardwiring of biochemical processes in these two phases. The present work reveals novel molecular details of the cell cycle and establishes proteome-wide CETSA as a new strategy to study modulation of protein-interaction states in intact cells.

PHF2 regulates genome topology and DNA replication in neural stem cells via cohesin.

Cohesin plays a crucial role in the organization of topologically-associated domains (TADs), which influence gene expression and DNA replication timing. Whether epigenetic regulators may affect TADs via cohesin to mediate DNA replication remains elusive. Here, we discover that the histone demethylase PHF2 associates with RAD21, a core subunit of cohesin, to regulate DNA replication in mouse neural stem cells (NSC). PHF2 loss impairs DNA replication due to the activation of dormant replication origins in NSC. Notably, the PHF2/RAD21 co-bound genomic regions are characterized by CTCF enrichment and epigenomic features that resemble efficient, active replication origins, and can act as boundaries to separate adjacent domains. Accordingly, PHF2 loss weakens TADs and chromatin loops at the co-bound loci due to reduced RAD21 occupancy. The observed topological and DNA replication defects in PHF2 KO NSC support a cohesin-dependent mechanism. Furthermore, we demonstrate that the PHF2/RAD21 complex exerts little effect on gene regulation, and that PHF2's histone-demethylase activity is dispensable for normal DNA replication and proliferation of NSC. We propose that PHF2 may serve as a topological accessory to cohesin for cohesin localization to TADs and chromatin loops, where cohesin represses dormant replication origins directly or indirectly, to sustain DNA replication in NSC.

Plant YABBY transcription factors: a review of gene expression, biological functions, and prospects.

Transcription factors often contain several different functional regions, including DNA-binding domains, and play an important regulatory role in plant growth, development, and the response to external stimuli. YABYY transcription factors are plant-specific and contain two special domains (N-terminal C2C2 zinc-finger and C-terminal helix-loop-helix domains) that are indispensable. Specifically, YABBY transcription factors play key roles in maintaining the polarity of the adaxial-abaxial axis of leaves, as well as in regulating: vegetative and reproductive growth, hormone response, stress resistance, and secondary metabolite synthesis in plants. Recently, the identification and functional verification of YABBY transcription factors in different plants has increased. On this basis, we summarize recent advances in the: identification, classification, expression patterns, and functions of the YABBY transcription factor family. The normal expression and function of YABBY transcription factors rely on a regulatory network that is established through the interaction of YABBY family members with other genes. We discuss the interaction network of YABBY transcription factors during leaf polarity establishment and floral organ development. This article provides a reference for research on YABBY function, plant genetic improvement, and molecular breeding.

Associating Knee Osteoarthritis Progression with Temporal-Regional Graph Convolutional Network Analysis on MR Images.

BACKGROUND: Artificial intelligence shows promise in assessing knee osteoarthritis (OA) progression on MR images, but faces challenges in accuracy and interpretability. PURPOSE: To introduce a temporal-regional graph convolutional network (TRGCN) on MR images to study the association between knee OA progression status and network outcome. STUDY TYPE: Retrospective. POPULATION: 194 OA progressors (mean age, 62 ± 9 years) and 406 controls (mean age, 61 ± 9 years) from the OA Initiative were randomly divided into training (80%) and testing (20%) cohorts. FIELD STRENGTH/SEQUENCE: Sagittal 2D IW-TSE-FS (IW) and 3D-DESS-WE (DESS) at 3T. ASSESSMENT: Anatomical subregions of cartilage, subchondral bone, meniscus, and the infrapatellar fat pad at baseline, 12-month, and 24-month were automatically segmented and served as inputs to form compartment-based graphs for a TRGCN model, which containing both regional and temporal information. The performance of models based on (i) clinical variables alone, (ii) radiologist score alone, (iii) combined features (containing i and ii), (iv) composite TRGCN (combining TRGCN, i and ii), (v) radiomics features, (vi) convolutional neural network based on Densenet-169 were compared. STATISTICAL TESTS: DeLong test was performed to compare the areas under the ROC curve (AUC) of all models. Additionally, interpretability analysis was done to evaluate the contributions of individual regions. A P value <0.05 was considered significant. RESULTS: The composite TRGCN outperformed all other models with AUCs of 0.841 (DESS) and 0.856 (IW) in the testing cohort (all P < 0.05). Interpretability analysis highlighted cartilage's importance over other structures (42%-45%), tibiofemoral joint's (TFJ) dominance over patellofemoral joint (PFJ) (58%-67% vs. 12%-37%), and importance scores changes in compartments over time (TFJ vs. PFJ: baseline: 44% vs. 43%, 12-month: 52% vs. 39%, 24-month: 31% vs. 48%). DATA CONCLUSION: The composite TRGCN, capturing temporal and regional information, demonstrated superior discriminative ability compared with other methods, providing interpretable insights for identifying knee OA progression. TECHNICAL EFFICACY: Stage 2.

Inactivating Celsr2 promotes motor axon fasciculation and regeneration in mouse and human.

Understanding new modulators of axon regeneration is central to neural repair. Our previous work demonstrated critical roles of atypical cadherin Celsr2 during neural development, including cilia organization, neuron migration and axon navigation. Here, we address its role in axon regeneration. We show that Celsr2 is highly expressed in both mouse and human spinal motor neurons. Celsr2 knockout promotes axon regeneration and fasciculation in mouse cultured spinal explants. Similarly, cultured Celsr2 mutant motor neurons extend longer neurites and larger growth cones, with increased expression of end-binding protein 3 and higher potassium-induced calcium influx. Mice with Celsr2 conditional knockout in spinal motor neurons do not exhibit any behavioural deficits; however, after branchial plexus injury, axon regeneration and functional forelimb locomotor recovery are significantly improved. Similarly, knockdown of CELSR2 using shRNA interference in cultured human spinal motor explants and motor neurons increases axonal fasciculation and growth. In mouse adult spinal cord after root avulsion, in mouse embryonic spinal cords, and in cultured human motor neurons, Celsr2 downregulation is accompanied by increased levels of GTP-bound Rac1 and Cdc42, and of JNK and c-Jun. In conclusion, Celsr2 negatively regulates motor axon regeneration and is a potential target to improve neural repair.

PTA-Det: Point Transformer Associating Point Cloud and Image for 3D Object Detection.

In autonomous driving, 3D object detection based on multi-modal data has become an indispensable perceptual approach when facing complex environments around the vehicle. During multi-modal detection, LiDAR and a camera are simultaneously applied for capturing and modeling. However, due to the intrinsic discrepancies between the LiDAR point and camera image, the fusion of the data for object detection encounters a series of problems, which results in most multi-modal detection methods performing worse than LiDAR-only methods. In this investigation, we propose a method named PTA-Det to improve the performance of multi-modal detection. Accompanied by PTA-Det, a Pseudo Point Cloud Generation Network is proposed, which can represent the textural and semantic features of keypoints in the image by pseudo points. Thereafter, through a transformer-based Point Fusion Transition (PFT) module, the features of LiDAR points and pseudo points from an image can be deeply fused under a unified point-based form. The combination of these modules can overcome the main obstacle of cross-modal feature fusion and achieves a complementary and discriminative representation for proposal generation. Extensive experiments on KITTI dataset support the effectiveness of PTA-Det, achieving a mAP (mean average precision) of 77.88% on the car category with relatively few LiDAR input points.

Mixing and Flow Transition in an Optimized Electrokinetic Turbulent Micromixer.

Micromixer is a key element in a lab on a chip for broad applications in the analysis and measurement of chemistry and engineering. Previous investigations reported that electrokinetic (EK) turbulence could be realized in a "Y" type micromixer with a cross-sectional dimension of 100 µm order. Although the ultrafast turbulent mixing can be generated at a bulk flow Reynolds number on the order of unity, the micromixer has not been optimized. In this investigation, we systematically investigated the influence of electric field intensity, AC frequency, electric conductivity ratio, and channel width at the entrance on the mixing effect and transition electric Rayleigh number in the "Y" type electrokinetic turbulent micromixer. It is found that the optimal mixing is realized in a 350 µm wide micromixer, under 100 kHz and 1.14 × 105 V/m AC electric field, with an electric conductivity ratio of 1:3000. Under these conditions, a degree of mixedness of 0.93 can be achieved at 84 µm from the entrance and 100 ms. A further investigation of the critical electric field and the critical electric Rayleigh number indicates that the most unstable condition of EK flow instability is inconsistent with that of the optimal mixing in EK turbulence. To predict the evolution of EK flow under high Raσ and guide the design of EK turbulent micromixers, it is necessary to apply a computational turbulence model instead of linear instability analysis.

Early Forebrain Neurons and Scaffold Fibers in Human Embryos.

Neural progenitor proliferation, neuronal migration, areal organization, and pioneer axon wiring are critical events during early forebrain development, yet remain incompletely understood, especially in human. Here, we studied forebrain development in human embryos aged 5 to 8 postconceptional weeks (WPC5-8), stages that correspond to the neuroepithelium/early marginal zone (WPC5), telencephalic preplate (WPC6 & 7), and incipient cortical plate (WPC8). We show that early telencephalic neurons are formed at the neuroepithelial stage; the most precocious ones originate from local telencephalic neuroepithelium and possibly from the olfactory placode. At the preplate stage, forebrain organization is quite similar in human and mouse in terms of areal organization and of differentiation of Cajal-Retzius cells, pioneer neurons, and axons. Like in mice, axons from pioneer neurons in prethalamus, ventral telencephalon, and cortical preplate cross the diencephalon-telencephalon junction and the pallial-subpallial boundary, forming scaffolds that could guide thalamic and cortical axons at later stages. In accord with this model, at the early cortical plate stage, corticofugal axons run in ventral telencephalon in close contact with scaffold neurons, which express CELSR3 and FZD3, two molecules that regulates formation of similar scaffolds in mice.

Prenatal sevoflurane exposure causes abnormal development of the entorhinal cortex in rat offspring.

As a gamma-aminobutyric acid type A receptor agonist sevoflurane is a common general anesthetic used in anesthesia and affects the neural development in offspring. We hypothesized that sevoflurane could regulate interneurons via the neuregulin-1-epidermal growth factor receptor-4 (NRG1-ErbB4) pathway in the entorhinal cortex (ECT) of the middle pregnancy. Six female rats in middle pregnancy (14.5 days of pregnancy) were randomly and equally divided into sevoflurane (SeV) and control groups. The rats in the SeV group were exposed to 4% sevoflurane for 3 hours. The expression levels of NRG1 and ErbB4, parvalbumin (PV) and glutamic acid decarboxylase (GAD67), and N-methyl-D-aspartate receptor subunit 2A (NR2A) and subunit 2B (NR2B) in offspring were examined through immunohistochemistry. The pyramidal neurons in the ECT were examined via Golgi staining. The levels of NRG1 and ErbB4 were significantly decreased (P < 0.01) and the levels of PV and GAD67 (interneurons) were found to be decreased in the SeV group (P < 0.01). The level of NR2B was found to be increased while the level of NR2A being decreased in the SeV group (P < 0.01). The development of pyramidal neurons was abnormal in the SeV group (P < 0.05). Conclusively, prenatal sevoflurane exposure could lead to the disturbance of the interneurons by activating the NRG1-ErbB4 pathway and subsequently result in abnormal development of pyramidal neurons in middle pregnancy. Prenatal sevoflurane exposure in middle pregnancy could be potentially harmful to the neural development of rat offspring. This study may reveal a novel pathway in the influence mechanism of sevoflurane on rat offspring.

Prenatal sevoflurane exposure causes neuronal excitatory/inhibitory imbalance in the prefrontal cortex and neurofunctional abnormality in rats.

The balance of excitatory and inhibitory neurons in the central nervous system is critical for maintaining brain function and sevoflurane, a general anesthetic and an GABA receptor modulator, may change the balance of excitatory and inhibitory neurons in the cortex during early brain development. Herein, we investigated whether prenatal sevoflurane exposure (PSE) disturbs cortical neuronal development and brain function. Pregnant rats at the gestational day 14.5 were subjected to sevoflurane exposure at 3.0% for 3 h and their offspring were studied thereafter. We found a significant increase of parvalbumin-positive neurons, vesicular GABA transporter (VGAT) and GAD67 expression, and GABA neurotransmitter, and a significant decrease of vesicular glutamate transporter 1 (VGLUT1) expression and glutamate in the medial prefrontal cortex (mPFC) of offspring. Pyramidal neurons showed atrophy with shorter dendrites, less branches and lower spine density visualized by Golgi stain and a decrease of excitability with the increased miniature inhibitory postsynaptic current (mIPSC) frequency and amplitude, the decreased miniature excitatory postsynaptic current (mEPSC) frequency and excitation/inhibition (E/I) ratio using whole-cell recording in offspring. There was a significant increase of inhibitory synapse in the mPFC detected by electron microscopy. Furthermore, PSE animals showed hypo-excitatory phenotype including depression-like behaviors and learning deficits. Thus, our studies provide novel evidence that PSE causes the persisted imbalance of excitatory and inhibitory neurons in the mPFC, and this is very likely the mechanisms of the sevoflurane-induced brain functional abnormalities.

Combined non-intubated anaesthesia and paravertebral nerve block in comparison with intubated anaesthesia in children undergoing video-assisted thoracic surgery.

BACKGROUND: This study is to investigate if non-intubated anaesthesia combined with paravertebral nerve block (PVNB) can enhance recovery in children undergoing video-assisted thoracic surgery (VATS). METHODS: A randomized controlled trial including 60 patients aged 3 to 8 years old who underwent elective VATS was performed. They were randomly assigned to receive non-intubated anaesthesia combined with PVNB or general anaesthesia with tracheal intubation (1:1 ratio). The primary outcome was the length of postoperative in-hospital stay. The secondary outcomes included emergence time, the incidence of emergence delirium, time to first feeding, time to first out-of-bed activity, pain score and in-hospital complications. RESULTS: The non-intubated group had shorter postoperative in-hospital stay than the control group (4 days [IQR, 4-6] vs 5 days [IQR, 5-8], 95% CI 0-2; P = .013). When compared to the control group, the incidence of emergence delirium (odds ratio [OR] 3.39, 95% CI 1.01-11.41; P = .043), emergence time, duration in the PACU, time to first eating food, first out-of-bed activity, pain score and consumption of sufentanil (at 6 and 12 hours after surgery) were decreased in the intervention group. In contrast, the incidence of airway complications was higher in the control than the intervention group (27.6% vs 6.9%, P = .037). There was no statistical significance in the occurrence of PONV, pneumothorax and other complications between the two groups. CONCLUSIONS: Non-intubated anaesthesia combined with PVNB enhances recovery in paediatric patients for video-assisted thoracic surgery although further multi-centre study is needed.

AMD1 is essential for ESC self-renewal and is translationally down-regulated on differentiation to neural precursor cells.

The gene expression networks governing embryonic stem cell (ESC) pluripotency are complex and finely regulated during differentiation toward specific lineages. We describe a new role for Amd1 (adenosyl methionine decarboxylase), a key enzyme in the polyamine synthesis pathway, in regulating both ESC self-renewal and differentiation to the neural lineage. Amd1 is highly expressed in ESCs and is translationally down-regulated by the neural precursor cell (NPC)-enriched microRNA miR-762 during NPC differentiation. Overexpression of Amd1 or addition of the polyamine spermine blocks ESC-to-NPC conversion, suggesting Amd1 must be down-regulated to decrease the levels of inhibitory spermine during differentiation. In addition, we demonstrate that high levels of Amd1 are required for maintenance of the ESC state. We show that forced overexpression of Amd1 in ESCs results in maintenance of high Myc levels and a delay in differentiation on removal of LIF. We propose that Amd1 is a major regulator of ESC self-renewal and that its essential role lies in its regulation of Myc levels within the cell.

Adaptive willingness resolves social dilemma in network populations.

Cooperation is an effective manner to enable different elements of complex networks to work well. In this work, we propose a coevolution mechanism of learning willingness in the network population: an agent will be more likely to imitate a given neighbor's strategy if her payoff is not less than the average performance of all her neighbors. Interestingly, increase of learning willingness will greatly promote cooperation even under the environment of extremely beneficial temptation to defectors. Through a microscopic analysis, it is unveiled that cooperators are protected due to the appearance of large-size clusters. Pair approximation theory also validates all these findings. Such an adaptive mechanism thus provides a feasible solution to relieve social dilemmas and will inspire further studies.

Dexmedetomidine attenuates spinal cord ischemia-reperfusion injury through both anti-inflammation and anti-apoptosis mechanisms in rabbits.

BACKGROUND: Dexmedetomidine (Dex) can improve neuronal viability and protect the spinal cord from ischemia-reperfusion (I/R) injury, but the underlying mechanisms are not fully understood. This study investigated the effects of dexmedetomidine on the toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NF-κB) inflammatory system and caspase-3 dependent apoptosis induced by spinal cord ischemia-reperfusion injury. METHODS: Twenty-four rabbits were divided into three groups: I/R, Dex (10 µg/kg/h prior to ischemia until reperfusion), and Sham. Abdominal aortic occlusion was carried out for 30 min in the I/R and Dex groups. Hindlimb motor function was assessed using the Tarlov scoring system for gait evaluation. Motor neuron survival and apoptosis in the ventral grey matter were assessed by haematoxylin-eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labelling staining. The expression and localisation of ionised calcium-binding adaptor molecule 1, TLR4, NF-κB and caspase-3 were assessed by immunoreactivity analysis. The levels of interleukin 1ß and tumour necrosis factor α were assessed using enzyme-linked immunosorbent assays. RESULTS: Perioperative treatment with dexmedetomidine was associated with a significant preservation of locomotor function following spinal cord ischemia-reperfusion injury with increased neuronal survival in the spinal cord compared to control. In addition, dexmedetomidine suppressed microglial activation, inhibited the TLR4-mediated NF-κB signalling pathway, and inhibited the caspase-3 dependent apoptosis. CONCLUSIONS: Dexmedetomidine confers neuroprotection against spinal cord ischemia-reperfusion injury through suppression of spinal cord inflammation and neuronal apoptosis. A reduction in microglial activation and inhibition of both the TLR4-mediated NF-κB signalling pathway and caspase-3 dependent apoptosis are implicated.

A chemical-inducible CRISPR-Cas9 system for rapid control of genome editing.

CRISPR-Cas9 has emerged as a powerful technology that enables ready modification of the mammalian genome. The ability to modulate Cas9 activity can reduce off-target cleavage and facilitate precise genome engineering. Here we report the development of a Cas9 variant whose activity can be switched on and off in human cells with 4-hydroxytamoxifen (4-HT) by fusing the Cas9 enzyme with the hormone-binding domain of the estrogen receptor (ERT2). The final optimized variant, termed iCas, showed low endonuclease activity without 4-HT but high editing efficiency at multiple loci with the chemical. We also tuned the duration and concentration of 4-HT treatment to reduce off-target genome modification. Additionally, we benchmarked iCas against other chemical-inducible methods and found that it had the fastest on rate and that its activity could be toggled on and off repeatedly. Collectively, these results highlight the utility of iCas for rapid and reversible control of genome-editing function.

Median Effective Dose of Intranasal Dexmedetomidine for Rescue Sedation in Pediatric Patients Undergoing Magnetic Resonance Imaging.

BACKGROUND: The median effective dose (ED50) of intranasal dexmedetomidine after failed chloral hydrate sedation has not been described for children. This study aims to determine the ED50 of intranasal dexmedetomidine for rescue sedation in children aged 1 to 36 months, who were inadequately sedated by chloral hydrate administration during magnetic resonance imaging (MRI). METHODS: This study was performed on 120 children, who were 1 to 36 months old and underwent MRI scanning. Intranasal dexmedetomidine was administered as a rescue sedative to children not adequately sedated after the initial oral dose of chloral hydrate (50 mg/kg). Children were stratified into four age groups. ED50 values were estimated from the up-and-down method of Dixon and Massey and probit regression. Other variables included induction time, time to wake up, vital signs, oxygen saturation, MRI scanning time, and recovery characteristics. RESULTS: ED50 of intranasal dexmedetomidine for rescue sedation was 0.4 µg/kg (95% CI, 0.34 to 0.50) in children aged 1 to 6 months, 0.5 µg/kg (95% CI, 0.48 to 0.56) in children aged 7 to 12 months, 0.9 µg/kg (95% CI, 0.83 to 0.89) in children aged 13 to 24 months, and 1.0 µg/kg (95% CI, 0.94 to 1.07) in children aged 25 to 36 months. There were no significant differences in sedation induction time or time to wake up between the different age groups. Additionally, no significant adverse hemodynamic or hypoxemic effects were noted. CONCLUSIONS: The authors determined the ED50 for rescue sedation using intranasal dexmedetomidine after failed chloral hydrate sedation in children. It was found that ED50 increases with advancing age during the first 3 yr of life.

Ketamine administered to pregnant rats in the second trimester causes long-lasting behavioral disorders in offspring.

Commonly used anesthetic agents, e.g. ketamine, may be neurotoxic to the developing brain but there has been little attention to the neurobehavioral consequences for offspring when used for maternal anesthesia. We hypothesize that treatment of pregnant rats with ketamine during the second trimester would affect brain development of the offspring. Pregnant rats on gestational day 14, about equal to midtrimester pregnancy in humans, received a sedative dose of ketamine intravenously for 2h. Brain hippocampal morphology of their pups at postnatal days 0 (P0) and P30 was examined by Nissl-staining and the characteristics of dendrites were determined using the Golgi-Cox staining, while cell proliferation in subventricular zone (SVZ) and dentate gyrus (DG) was labeled with bromodeoxyuridine (BrdU). Their neurobehavioral functions were tested at P25-30 after which the NR1 and NR2 subunits of N-methyl-d-aspartate (NMDA) receptor, brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD-95) in the hippocampus were analyzed by western blot. When pregnant rats were exposed to ketamine, there was neuronal loss, pyramidal neuronal abnormality and reduced cell proliferation in the hippocampus of offspring. These morphological abnormalities were associated with depression- and anxiety-like behaviors, and impaired memory up to young adult age. The treatment further caused NR2A receptor subunit up-regulation and NR2B receptor subunit, BDNF and PSD-95 down-regulation. These data suggest that maternal anesthesia with ketamine during the fetal brain development period can cause fetal brain damage and subsequent neurobehavioral abnormality, which is likely associated with the imbalanced expression of NMDA receptor subunits.

Hepatocyte-intrinsic SMN deficiency drives metabolic dysfunction and liver steatosis in spinal muscular atrophy.

Spinal Muscular Atrophy (SMA) is typically characterized as a motor neuron disease, but extra-neuronal phenotypes are present in almost every organ in severely affected patients and animal models. Extra-neuronal phenotypes were previously underappreciated as patients with severe SMA phenotypes usually died in infancy; however, with current treatments for motor neurons increasing patient lifespan, impaired function of peripheral organs may develop into significant future comorbidities and lead to new treatment-modified phenotypes. Fatty liver is seen in SMA animal models , but generalizability to patients and whether this is due to hepatocyte-intrinsic Survival Motor Neuron (SMN) protein deficiency and/or subsequent to skeletal muscle denervation is unknown. If liver pathology in SMA is SMN-dependent and hepatocyte-intrinsic, this suggests SMN repleting therapies must target extra-neuronal tissues and motor neurons for optimal patient outcome. Here we showed that fatty liver is present in SMA and that SMA patient-specific iHeps were susceptible to steatosis. Using proteomics, functional studies and CRISPR/Cas9 gene editing, we confirmed that fatty liver in SMA is a primary SMN-dependent hepatocyte-intrinsic liver defect associated with mitochondrial and other hepatic metabolism implications. These pathologies require monitoring and indicate need for systematic clinical surveillance and additional and/or combinatorial therapies to ensure continued SMA patient health.

METTL8 links mt-tRNA m3C modification to the HIF1α/RTK/Akt axis to sustain GBM stemness and tumorigenicity.

Epitranscriptomic RNA modifications are crucial for the maintenance of glioma stem cells (GSCs), the most malignant cells in glioblastoma (GBM). 3-methylcytosine (m3C) is a new epitranscriptomic mark on RNAs and METTL8 represents an m3C writer that is dysregulated in cancer. Although METTL8 has an established function in mitochondrial tRNA (mt-tRNA) m3C modification, alternative splicing of METTL8 can also generate isoforms that localize to the nucleolus where they may regulate R-loop formation. The molecular basis for METTL8 dysregulation in GBM, and which METTL8 isoform(s) may influence GBM cell fate and malignancy remain elusive. Here, we investigated the role of METTL8 in regulating GBM stemness and tumorigenicity. In GSC, METTL8 is exclusively localized to the mitochondrial matrix where it installs m3C on mt-tRNAThr/Ser(UCN) for mitochondrial translation and respiration. High expression of METTL8 in GBM is attributed to histone variant H2AZ-mediated chromatin accessibility of HIF1α and portends inferior glioma patient outcome. METTL8 depletion impairs the ability of GSC to self-renew and differentiate, thus retarding tumor growth in an intracranial GBM xenograft model. Interestingly, METTL8 depletion decreases protein levels of HIF1α, which serves as a transcription factor for several receptor tyrosine kinase (RTK) genes, in GSC. Accordingly, METTL8 loss inactivates the RTK/Akt axis leading to heightened sensitivity to Akt inhibitor treatment. These mechanistic findings, along with the intimate link between METTL8 levels and the HIF1α/RTK/Akt axis in glioma patients, guided us to propose a HIF1α/Akt inhibitor combination which potently compromises GSC proliferation/self-renewal in vitro. Thus, METTL8 represents a new GBM dependency that is therapeutically targetable.

[Discussion on internal fixation of Hoffa fractures].

Hoffa fracture is an unstable intra-articular fracture with significant redisplacement tendency. It is easy to be missed diagnosis when accompanied by distal intercondylar or supracondylar fracture of femur. CT scan is the gold standard for the diagnosis of Hoffa fracture. The treatment principles are anatomic reduction of the articular surface, reliable internal fixation, and early functional activity. At present, the main treatment is arthroscopic screw fixation. During screw fixation, the tail cap of screw should be buried, resulting in non-healing iatrogenic injury of articular cartilage. In the early postoperative functional activity of knee joint, fracture block was repeatedly subjected to backward and upward shear force under the action of the tibial plateau, which is the main reason for the failure of internal fixation. Plate assisted screw fixation could increase local mechanical stability, but it still cannot avoid the defects of iatrogenic cartilage injury. At the same time, plate molding is required during the operation due to the absence of special anatomical plates, resulting in increased surgical trauma and time-consuming surgery. The ideal fixation method for Hoffa fracture should include:(1) Avoid iatrogenic injury of articular surface cartilage. (2) With the rear anti-shear barrier plate function.(3) The internal fixator is closer to the load interface, so as to obtain greater load and better fixed strength.