Mechanisms and regulation of cholesterol homeostasis.

Cholesterol homeostasis is vital for proper cellular and systemic functions. Disturbed cholesterol balance underlies not only cardiovascular disease but also an increasing number of other diseases such as neurodegenerative diseases and cancers. The cellular cholesterol level reflects the dynamic balance between biosynthesis, uptake, export and esterification - a process in which cholesterol is converted to neutral cholesteryl esters either for storage in lipid droplets or for secretion as constituents of lipoproteins. In this Review, we discuss the latest advances regarding how each of the four parts of cholesterol metabolism is executed and regulated. The key factors governing these pathways and the major mechanisms by which they respond to varying sterol levels are described. Finally, we discuss how these pathways function in a concerted manner to maintain cholesterol homeostasis.

Cholesterol transport through lysosome-peroxisome membrane contacts.

Cholesterol is dynamically transported among organelles, which is essential for multiple cellular functions. However, the mechanism underlying intracellular cholesterol transport has remained largely unknown. We established an amphotericin B-based assay enabling a genome-wide shRNA screen for delayed LDL-cholesterol transport and identified 341 hits with particular enrichment of peroxisome genes, suggesting a previously unappreciated pathway for cholesterol transport. We show dynamic membrane contacts between peroxisome and lysosome, which are mediated by lysosomal Synaptotagmin VII binding to the lipid PI(4,5)P2 on peroxisomal membrane. LDL-cholesterol enhances such contacts, and cholesterol is transported from lysosome to peroxisome. Disruption of critical peroxisome genes leads to cholesterol accumulation in lysosome. Together, these findings reveal an unexpected role of peroxisome in intracellular cholesterol transport. We further demonstrate massive cholesterol accumulation in human patient cells and mouse model of peroxisomal disorders, suggesting a contribution of abnormal cholesterol accumulation to these diseases.

Inhibition of ASGR1 decreases lipid levels by promoting cholesterol excretion.

High cholesterol is a major risk factor for cardiovascular disease1. Currently, no drug lowers cholesterol through directly promoting cholesterol excretion. Human genetic studies have identified that the loss-of-function Asialoglycoprotein receptor 1 (ASGR1) variants associate with low cholesterol and a reduced risk of cardiovascular disease2. ASGR1 is exclusively expressed in liver and mediates internalization and lysosomal degradation of blood asialoglycoproteins3. The mechanism by which ASGR1 affects cholesterol metabolism is unknown. Here, we find that Asgr1 deficiency decreases lipid levels in serum and liver by stabilizing LXRα. LXRα upregulates ABCA1 and ABCG5/G8, which promotes cholesterol transport to high-density lipoprotein and excretion to bile and faeces4, respectively. ASGR1 deficiency blocks endocytosis and lysosomal degradation of glycoproteins, reduces amino-acid levels in lysosomes, and thereby inhibits mTORC1 and activates AMPK. On one hand, AMPK increases LXRα by decreasing its ubiquitin ligases BRCA1/BARD1. On the other hand, AMPK suppresses SREBP1 that controls lipogenesis. Anti-ASGR1 neutralizing antibody lowers lipid levels by increasing cholesterol excretion, and shows synergistic beneficial effects with atorvastatin or ezetimibe, two widely used hypocholesterolaemic drugs. In summary, this study demonstrates that targeting ASGR1 upregulates LXRα, ABCA1 and ABCG5/G8, inhibits SREBP1 and lipogenesis, and therefore promotes cholesterol excretion and decreases lipid levels.

GRAMD1/ASTER-mediated cholesterol transport promotes Smoothened cholesterylation at the endoplasmic reticulum.

Hedgehog (Hh) signaling pathway plays a pivotal role in embryonic development. Hh binding to Patched1 (PTCH1) derepresses Smoothened (SMO), thereby activating the downstream signal transduction. Covalent SMO modification by cholesterol in its cysteine-rich domain (CRD) is essential for SMO function. SMO cholesterylation is a calcium-accelerated autoprocessing reaction, and STIM1-ORAI1-mediated store-operated calcium entry promotes cholesterylation and activation of endosome-localized SMO. However, it is unknown whether the Hh-PTCH1 interplay regulates the activity of the endoplasmic reticulum (ER)-localized SMO. Here, we found that PTCH1 inhibited the COPII-dependent export of SMO from the ER, whereas Hh promoted this process. The RRxWxR amino acid motif in the cytosolic tail of SMO was essential for COPII recognition, ciliary localization, and signal transduction activity. Hh and PTCH1 regulated cholesterol modification of the ER-localized SMO, and SMO cholesterylation accelerated its exit from ER. The GRAMD1/ASTER sterol transport proteins facilitated cholesterol transfer to ER from PM, resulting in increased SMO cholesterylation and enhanced Hh signaling. Collectively, we reveal a regulatory role of GRAMD-mediated cholesterol transport in ER-resident SMO maturation and Hh signaling.

Cholesterol Homeostatic Regulator SCAP-SREBP2 Integrates NLRP3 Inflammasome Activation and Cholesterol Biosynthetic Signaling in Macrophages.

Cholesterol metabolism has been linked to immune functions, but the mechanisms by which cholesterol biosynthetic signaling orchestrates inflammasome activation remain unclear. Here, we have shown that NLRP3 inflammasome activation is integrated with the maturation of cholesterol master transcription factor SREBP2. Importantly, SCAP-SREBP2 complex endoplasmic reticulum-to-Golgi translocation was required for optimal activation of the NLRP3 inflammasome both in vitro and in vivo. Enforced cholesterol biosynthetic signaling by sterol depletion or statins promoted NLPR3 inflammasome activation. However, this regulation did not predominantly depend on changes in cholesterol homeostasis controlled by the transcriptional activity of SREBP2, but relied on the escort activity of SCAP. Mechanistically, NLRP3 associated with SCAP-SREBP2 to form a ternary complex which translocated to the Golgi apparatus adjacent to a mitochondrial cluster for optimal inflammasome assembly. Our study reveals that, in addition to controlling cholesterol biosynthesis, SCAP-SREBP2 also serves as a signaling hub integrating cholesterol metabolism with inflammation in macrophages.

Feeding induces cholesterol biosynthesis via the mTORC1-USP20-HMGCR axis.

Cholesterol is an essential lipid and its synthesis is nutritionally and energetically costly1,2. In mammals, cholesterol biosynthesis increases after feeding and is inhibited under fasting conditions3. However, the regulatory mechanisms of cholesterol biosynthesis at the fasting-feeding transition remain poorly understood. Here we show that the deubiquitylase ubiquitin-specific peptidase 20 (USP20) stabilizes HMG-CoA reductase (HMGCR), the rate-limiting enzyme in the cholesterol biosynthetic pathway, in the feeding state. The post-prandial increase in insulin and glucose concentration stimulates mTORC1 to phosphorylate USP20 at S132 and S134; USP20 is recruited to the HMGCR complex and antagonizes its degradation. The feeding-induced stabilization of HMGCR is abolished in mice with liver-specific Usp20 deletion and in USP20(S132A/S134A) knock-in mice. Genetic deletion or pharmacological inhibition of USP20 markedly decreases diet-induced body weight gain, reduces lipid levels in the serum and liver, improves insulin sensitivity and increases energy expenditure. These metabolic changes are reversed by expression of the constitutively stable HMGCR(K248R). This study reveals an unexpected regulatory axis from mTORC1 to HMGCR via USP20 phosphorylation and suggests that inhibitors of USP20 could be used to lower cholesterol levels to treat metabolic diseases including hyperlipidaemia, liver steatosis, obesity and diabetes.

Bioinformatics toolbox for exploring target mutation-induced drug resistance.

Drug resistance is increasingly among the main issues affecting human health and threatening agriculture and food security. In particular, developing approaches to overcome target mutation-induced drug resistance has long been an essential part of biological research. During the past decade, many bioinformatics tools have been developed to explore this type of drug resistance, and they have become popular for elucidating drug resistance mechanisms in a low cost, fast and effective way. However, these resources are scattered and underutilized, and their strengths and limitations have not been systematically analyzed and compared. Here, we systematically surveyed 59 freely available bioinformatics tools for exploring target mutation-induced drug resistance. We analyzed and summarized these resources based on their functionality, data volume, data source, operating principle, performance, etc. And we concisely discussed the strengths, limitations and application examples of these tools. Specifically, we tested some predictive tools and offered some thoughts from the clinician's perspective. Hopefully, this work will provide a useful toolbox for researchers working in the biomedical, pesticide, bioinformatics and pharmaceutical engineering fields, and a good platform for non-specialists to quickly understand drug resistance prediction.

Cholesterol Modification of Smoothened Is Required for Hedgehog Signaling.

Hedgehog (Hh) has been known as the only cholesterol-modified morphogen playing pivotal roles in development and tumorigenesis. A major unsolved question is how Hh signaling regulates the activity of Smoothened (SMO). Here, we performed an unbiased biochemical screen and identified that SMO was covalently modified by cholesterol on the Asp95 (D95) residue through an ester bond. This modification was inhibited by Patched-1 (Ptch1) but enhanced by Hh. The SMO(D95N) mutation, which could not be cholesterol modified, was refractory to Hh-stimulated ciliary localization and failed to activate downstream signaling. Furthermore, homozygous SmoD99N/D99N (the equivalent residue in mouse) knockin mice were embryonic lethal with severe cardiac defects, phenocopying the Smo-/- mice. Together, the results of our study suggest that Hh signaling transduces to SMO through modulating its cholesterylation and provides a therapeutic opportunity to treat Hh-pathway-related cancers by targeting SMO cholesterylation.

Hyperactivation of SREBP induces pannexin-1-dependent lytic cell death.

Sterol-regulatory element binding proteins (SREBPs) are a conserved transcription factor family governing lipid metabolism. When cellular cholesterol level is low, SREBP2 is transported from the endoplasmic reticulum to the Golgi apparatus where it undergoes proteolytic activation to generate a soluble N-terminal fragment, which drives the expression of lipid biosynthetic genes. Malfunctional SREBP activation is associated with various metabolic abnormalities. In this study, we find that overexpression of the active nuclear form SREBP2 (nSREBP2) causes caspase-dependent lytic cell death in various types of cells. These cells display typical pyroptotic and necrotic signatures, including plasma membrane ballooning and release of cellular contents. However, this phenotype is independent of the gasdermin family proteins or mixed lineage kinase domain-like (MLKL). Transcriptomic analysis identifies that nSREBP2 induces expression of p73, which further activates caspases. Through whole-genome CRISPR-Cas9 screening, we find that Pannexin-1 (PANX1) acts downstream of caspases to promote membrane rupture. Caspase-3 or 7 cleaves PANX1 at the C-terminal tail and increases permeability. Inhibition of the pore-forming activity of PANX1 alleviates lytic cell death. PANX1 can mediate gasdermins and MLKL-independent cell lysis during TNF-induced or chemotherapeutic reagents (doxorubicin or cisplatin)-induced cell death. Together, this study uncovers a noncanonical function of SREBPs as a potentiator of programmed cell death and suggests that PANX1 can directly promote lytic cell death independent of gasdermins and MLKL.

EZH2 W113C is a gain-of-function mutation in B-cell lymphoma enabling both PRC2 methyltransferase activation and tazemetostat resistance.

Polycomb repressive complex 2 (PRC2) suppresses gene transcription by methylating lysine 27 of histone H3 (H3K27) and plays critical roles in embryonic development. Among the core PRC2 subunits, EZH2 is the catalytic subunit and EED allosterically activates EZH2 upon binding trimethylated H3K27 (H3K27me3). Activating mutations on Y641, A677, and A687 within the enzymatic SET (Su(Var)3 to 9, Enhancer-of-zeste, and Trithorax) domain of EZH2 have been associated with enhanced H3K27me3 and tumorigenicity of many cancers including B-cell lymphoma and melanoma. To tackle the critical residues outside the EZH2 SET domain, we examined EZH2 mutations in lymphoma from cancer genome databases and identified a novel gain-of-function mutation W113C, which increases H3K27me3 in vitro and in vivo and promotes CDKN2A silencing to a similar level as EZH2 Y641F. Different from other gain-of-function mutations, this mutation is located in the SET-activation loop at the EZH2 N terminus, which stabilizes the SET domain and facilitates substrate binding. This may explain how the W113C mutation increases PRC2 activity. Tazemetostat is a Food and Drug Administration-approved EZH2-binding inhibitor for follicular lymphoma treatment. Intriguingly, the W113C mutation leads to tazemetostat resistance in both H3K27 methylation and tumor proliferation. Another class of allosteric PRC2 inhibitor binding EED overcomes the resistance, effectively decreases H3K27me3, and blocks tumor proliferation in cells expressing EZH2 W113C. As this mutation is originally identified from lymphoma samples, our results demonstrated its activating characteristic and the deleterious consequence, provide insights on PRC2 regulation, and support the continued exploration of treatment optimization for lymphoma patients.

Pitavastatin sensitizes the EGFR-TKI associated resistance in lung cancer by inhibiting YAP/AKT/BAD-BCL-2 pathway.

BACKGROUND: Despite effective strategies, resistance in EGFR mutated lung cancer remains a challenge. Metabolic reprogramming is one of the main mechanisms of tumor drug resistance. A class of drugs known as "statins" inhibit lipid cholesterol metabolism and are widely used in patients with cardiovascular diseases. Previous studies have also documented its ability to improve the therapeutic impact in lung cancer patients who receive EGFR-TKI therapy. Therefore, the effect of statins on targeted drug resistance to lung cancer remains to be investigated. METHODS: Prolonged exposure to gefitinib resulted in the emergence of a resistant lung cancer cell line (PC9GR) from the parental sensitive cell line (PC9), which exhibited a traditional EGFR mutation. The CCK-8 assay was employed to assess the impact of various concentrations of pitavastatin on cellular proliferation. RNA sequencing was conducted to detect differentially expressed genes and their correlated pathways. For the detection of protein expression, Western blot was performed. The antitumor activity of pitavastatin was evaluated in vivo via a xenograft mouse model. RESULTS: PC9 gefitinib resistant strains were induced by low-dose maintenance. Cell culture and animal-related studies validated that the application of pitavastatin inhibited the proliferation of lung cancer cells, promoted cell apoptosis, and restrained the acquired resistance to EGFR-TKIs. KEGG pathway analysis showed that the hippo/YAP signaling pathway was activated in PC9GR cells relative to PC9 cells, and the YAP expression was inhibited by pitavastatin administration. With YAP RNA interference, pAKT, pBAD and BCL-2 expression was decreased, while BAX expression as increased. Accordingly, YAP down-regulated significantly increased apoptosis and decreased the survival rate of gefitinib-resistant lung cancer cells. After pAKT was increased by SC79, apoptosis of YAP down-regulated cells induced by gefitinib was decreased, and the cell survival rate was increased. Mechanistically, these effects of pitavastatin are associated with the YAP pathway, thereby inhibiting the downstream AKT/BAD-BCL-2 signaling pathway. CONCLUSION: Our study provides a molecular basis for the clinical application of the lipid-lowering drug pitavastatin enhances the susceptibility of lung cancer to EGFR-TKI drugs and alleviates drug resistance.

New Loss-of-Function Mutations in PCSK9 Reduce Plasma LDL Cholesterol.

BACKGROUND: Lower plasma levels of LDL (low-density lipoprotein) cholesterol (LDL-C) can reduce the risk of atherosclerotic cardiovascular disease. The loss-of-function mutations in PCSK9 (proprotein convertase subtilisin/kexin type 9) have been known to associate with low LDL-C in many human populations. PCSK9 genetic variants in Chinese Uyghurs who are at high risk of atherosclerotic cardiovascular disease due to their dietary habits have not been reported. METHODS: The study involved the whole-exome and target sequencing of college students from Uyghur and other ethnic groups in Xinjiang, China, for the association of PCSK9 loss-of-function mutations with low plasma levels of LDL-C. The mechanisms by which the identified mutations affect the function of PCSK9 were investigated in cultured cells using biochemical and cell assays. The causal effects of the identified PCSK9 mutations on LDL-C levels were verified in mice injected with adeno-associated virus expressing different forms of PCSK9 and fed a high-cholesterol diet. RESULTS: We identified 2 PCSK9 mutations-E144K and C378W-in Chinese Uyghurs with low plasma levels of LDL-C. The E144K and C378W mutations impaired the maturation and secretion of the PCSK9 protein, respectively. Adeno-associated virus-mediated expression of E144K and C378W mutants in Pcsk9 KO (knockout) mice fed a high-cholesterol diet also hampered PCSK9 secretion into the serum, resulting in elevated levels of LDL receptor in the liver and reduced levels of LDL-C in the serum. CONCLUSIONS: Our study shows that E144K and C378W are PCSK9 loss-of-function mutations causing low LDL-C levels in mice and probably in humans as well.

Tape Tarsorrhaphy in the Management of Lagophthalmos Caused by Severe Congenital Blepharoptosis Procedures.

BACKGROUND: Lagophthalmos, a common complication after blepharoptosis correction, has plagued oculoplastic surgeons. The goal of this study was to investigate the effect of tape eyelid closure on reducing the occurrence of lagophthalmos after blepharoptosis correction. METHODS: From April 2020 to June 2021, a total of 112 patients with severe congenital ptosis received corrective surgery at the Department of Plastic and Reconstructive Surgery, Xijing Hospital, Fourth Military Medical University. Of these, 48 underwent frontalis muscle advancement technique and 64 underwent conjoint fascial sheath suspension. Preoperative data collected included demographics, levator function, Bell's phenomenon, and marginal reflex distance 1 (MRD1). Postoperative data included surgery type, MRD1, eyelid closure function, aesthetic outcomes (including eyelid contour, eyelid symmetry, and eyelid crease), keratitis, and other complications. RESULTS: Frontalis muscle advancement technique group: the median of safe eye closure time was 7.3 months (positive Bell's phenomenon; interquartile range [IQR], 3.8-10.8 months) and 13.9 months (poor Bell's phenomenon; IQR, 11.6-16.1 months). There was a significant improvement between the preoperative and postoperative MRD1 (-1.52 ± 0.82 vs 3.85 ± 0.58 mm, P < 0.05). Conjoint fascial sheath suspension group: the median of safe eye closure time was 5.7 months (positive Bell's phenomenon; IQR, 2.9-8.5 months) and 12.4 months (poor Bell's phenomenon; IQR, 8.1-16.7 months). There was a significant improvement between the preoperative and postoperative MRD1 (-1.02 ± 0.91 vs 4.15 ± 1.03 mm, P < 0.05). All patients/guardians were satisfied with the aesthetic outcomes. CONCLUSIONS: Tape tarsorrhaphy is a safe, easy-to-learn method for treating lagophthalmos with a good aesthetic outcome.

The Aesthetic Evaluation of the Brow-Eye Continuum After Correction of Severe Congenital Ptosis in Children With Extended Frontalis Muscle Advancement Technique.

BACKGROUND: Severe congenital ptosis is a common ocular deformity in pediatric patients that can significantly impact visual development and aesthetic appearance, leading to negative psychosocial outcomes. The frontalis muscle advancement technique is a well-established surgical treatment for severe congenital ptosis. Aesthetic changes of the brow-eye continuum often plays an important role in ptosis surgery. METHODS: We conducted a single-center retrospective case series study of patients with severe congenital ptosis who underwent the frontalis muscle advancement technique at the Department of Plastic and Reconstructive Surgery, Xijing Hospital, Fourth Military Medical University between April 2020 and June 2021. The study aimed to evaluate the aesthetic changes of the eyebrow-eyelid continuum after surgery. The main outcome measurements included marginal reflex distance 1, palpebral fissure height, eyebrow position, upper eyelid to lower eyebrow distance, lower eyelid to upper eyebrow distance, and nasal base to lower eyelid distance. RESULTS: The study included 48 patients (66 eyelids), with 30 unilateral and 18 bilateral patients. Our analysis found that eyebrow height decreased by an average of 4.8% postoperatively relative to preoperatively in all patients. CONCLUSIONS: The frontalis muscle advancement technique has demonstrated effectiveness in achieving aesthetically pleasing outcomes in children with severe ptosis. It is crucial to pay careful attention to the brow-eye continuum during the correction process, as its harmony can greatly impact the final result.

Adhesion Coefficient Identification of Wheeled Mobile Robot under Unstructured Pavement.

Because of its uneven and large slope, unstructured pavement presents a great challenge to obtaining the adhesion coefficient of pavement. An estimation method of the peak adhesion coefficient of unstructured pavement on the basis of the extended Kalman filter is proposed in this paper. The identification accuracy of road adhesion coefficients under unstructured pavement is improved by introducing the equivalent suspension model to optimize the calculation of vertical wheel load and modifying vehicle acceleration combined with vehicle posture data. Finally, the multi-condition simulation experiments with Carsim are conducted, the estimation accuracy of the adhesion coefficient is at least improved by 3.6%, and then the precision and effectiveness of the designed algorithm in the article are verified.

Tape Eyelid Closure: An Effective Solution for Nocturnal Lagophthalmos in Patients with Ptosis and Poor Bell's Phenomenon.

BACKGROUND: Poor Bell's phenomenon is often considered a relative contraindication for ptosis surgery, as it increases the risk of corneal exposure and dry eye symptoms after surgery. However, the Bell's phenomenon may vary in different individuals and sleep stages, making it inaccurate to predict the position of the eye during sleep based on awake examination. This study aimed to investigate the role of Bell's phenomenon in ptosis surgery and the management of nocturnal lagophthalmos. METHODS: We conducted a retrospective case series of 23 patients with ptosis and poor Bell's phenomenon who underwent different surgical techniques at Xijing Hospital from April 2020 to June 2021. We assessed Bell's phenomenon at different stages of sleep and collected data on ptosis degree, surgical approach, lagophthalmos, complications, and outcomes. RESULTS: Of the total 23 patients originally considered for study, 9 with frontalis muscle advancement technique, 8 with conjoint fascial sheath suspension, 4 with levator resection technique, and 2 with levator aponeurosis plication technique. All patients achieved satisfactory correction of ptosis. One patient had prolonged lagophthalmos and underwent reoperation to lower the eyelid height. Other complications were minor and resolved with conservative treatment. CONCLUSION: We conclude that poor Bell's phenomenon is not a relative contraindication for ptosis surgery. Nocturnal lagophthalmos should be monitored after ptosis surgery regardless of the Bell's phenomenon results. Tape eyelid closure can be an effective solution to protect the corneal surface during nocturnal lagophthalmos. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Clinical Application of Long-Pulsed 800-Nm Diode Laser Depilation Technology on Microtia Reconstruction in 965 Patients.

BACKGROUND: The issue of hair growth on reconstructed ears has been a matter of concern for both patients and surgeons, despite the notable progress made in microtia reconstruction technology in recent times. OBJECTIVE: This study aims to present the practical implementation of long-pulsed 800-nm diode laser depilation technology in the field of auricular reconstruction. Furthermore, it seeks to establish a comprehensive and standardized protocol for utilizing lasers in the reconstruction of microtia ears. METHODS: A total of 965 patients (comprising 1021 ears) diagnosed with congenital microtia underwent treatment using 800-nm long-pulsed diode laser depilation. The participants received 1-3 treatment sessions with intervals of 25-30 days. To assess the effectiveness of the treatment, two independent observers compared photographs and measured the reduction in terminal hair count before and after the final session. Clinical outcomes were evaluated using VAS questionnaires, and any adverse events were diligently recorded. RESULTS: The findings indicated that the utilization of the long-pulsed 800-nm diode laser was both safe and efficient in achieving hair removal during microtia ear reconstruction. As additional sessions were conducted, pain scores demonstrated a decline, while adverse reactions remained minimal. LIMITATIONS: This is a retrospective single-institution study. CONCLUSION: The application of a long-pulsed 800-nm diode laser has been proved to be a safe and effective method for removing hair during the process of microtia ear reconstruction, involving the use of a tissue expander and autologous costal cartilage. To achieve satisfactory results in hair removal, it was found necessary to repeat the shots procedure two to three times. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Comparison of pediatric pelvic fractures and associated injuries caused by different types of road traffic accidents.

PURPOSE: To explore the clinical characteristics of pediatric pelvic fracturs caused by traffic accidents and to analyze the accompanying injuries and complications. METHODS: A total of 222 cases involved traffic accidents was enrolled in this case-control study. The data of children with pelvic fractures caused by traffic accidents who were admitted to our hospital from January 2006 to December 2021 were analyzed retrospectively. Sex, age, Tile classification, abbreviated injury scale score, injury severity score, mortality, and accompanying injuries were studied. The ANOVA was used for measurement data, and the non-parametric rank sum test was used for non-normally distributed data. The Fisher's exact probability method was used for the count data. RESULTS: Of all enrolled cases, 140 are boys and 82 are girls, including 144 aged < 6 years, 65 aged between 6 and 12 years, and 13 aged > 12 years. Depending on the injury mechanism, there are 15 cases involving pedestrians vs. motorcycles (PVM), 91 cases involving pedestrians vs. passenger cars (PVC), 78 cases involving pedestrians vs. commercial vehicles (PVV), and 38 cases involving motor vehicles vs. motor vehicles (MVM). Associated injuries are reported in 198 cases (89.2%), primarily involving the abdomen injury in 144 cases (64.9%), and lower limb injury in 99 cases (44.6%). PVV injury involves longer hospital stay (p = 0.004). Intensive care unit admission rate is significantly higher in the MVM group than in other groups (p = 0.004). Head injury (p = 0.001) and face injury (p = 0.037) are more common in the MVM group, whereas abdominal injury (p = 0.048) and lower limb injury (p = 0.037) are more common in the PVV group. In the MVM group, the brain injury (p = 0.004) and femoral neck injury (p = 0.044) are more common. In the PVM group, the mediastinum (p = 0.004), ear (p = 0.009), lumbar vertebrae (p = 0.008), and spinal cord (p = 0.011) are the most vulnerable regions, while in the PVV group, the perineum (p < 0.001), urethra (p = 0.001), rectum (p = 0.006), anus (p = 0.004), and lower limb soft tissues (p = 0.024) are the most vulnerable regions. Children aged > 12 years have higher pelvic abbreviated injury scale scores (p = 0.019). There are significant differences in the classification of pelvic fractures among children < 6, 6 - 12, and > 12 years of age, with Tile C being more likely to occur in children > 12 years of age (p = 0.033). Children aged > 12 years are more likely to sustain injuries to the spleen (p = 0.022), kidneys (p = 0.019), pancreas (p < 0.001), lumbar vertebrae (p = 0.013), and sacrum (p = 0.024). The MVM group has the highest complication rate (p = 0.003). CONCLUSION: PVC is the leading cause of the abdomen and lower extremities injury and has the most concomitant injuries. Different traffic injuries often lead to different associated injuries. Older children are more likely to sustain more severe pelvic fractures and peripelvic organs injuries. The MVM group has the highest extent of injury and complication rates.

Intracellular Cholesterol Transport by Sterol Transfer Proteins at Membrane Contact Sites.

Cholesterol is dynamically transported among membrane-bound organelles primarily by nonvesicular mechanisms. Sterol transfer proteins (STPs) bind cholesterol in their hydrophobic pockets and facilitate its transfer across the aqueous cytosol. However, STPs alone may not account for the specific and efficient movement of cholesterol between intracellular membranes. Accumulating evidence has shown that membrane contact sites (MCSs), regions where two distinct organelles are in close apposition to one another, can facilitate STP-mediated cholesterol trafficking in a cell. At some MCSs, cholesterol can move against its concentration by using phosphatidylinositol 4-phosphate (PI4P) metabolism as the driving force. Finally, the emergence of more MCSs and the discovery of a new STP family further highlight the crucial roles of MCSs and STPs in intracellular cholesterol transport.