Contribution of cuproptosis and Cu metabolism-associated genes to chronic obstructive pulmonary disease.

Airway epithelial cell injury plays a crucial role in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, a novel form of Cu-induced programmed cell death known as cuproptosis has not yet been thoroughly investigated in the context of COPD. Clinical reports have suggested that high copper exposure may increase the risk of COPD. In this study, we aimed to determine the expression and potential functions of cuproptosis-related genes and genes associated with copper metabolism in COPD. We initially identified 52 copper metabolism-related genes based on a review of the literature. Subsequently, we calculated the expression levels of these genes using data from four GEO datasets. To gain insights into the activated signalling pathways and underlying mechanisms in COPD patients, we conducted Gene Ontology (GO) and KEGG pathway analyses, examined protein-protein interactions, and performed weighted correlation network analysis. Our findings revealed that 18 key copper metabolism-related genes, including 5 cuproptosis-related genes, were significantly enriched in signalling pathways and biological processes associated with the development of COPD. Further analysis of clinical data and animal experiments confirmed the high expression of certain cuproptosis key regulators, such as DLD and CDKN2A, in both healthy smokers and COPD smokers. Additionally, these regulators exhibited abnormal expression in a COPD rat model. Notably, copper content was found to be elevated in the lung tissues of COPD rats, suggesting its potential involvement in cuproptosis. These findings provide an experimental foundation for further research into the role of cuproptosis in COPD. Targeting copper metabolism-related genes may represent an effective approach for the treatment of COPD.

Thiophene Cation Intercalation to Improve Band-Edge Integrity in Reduced-Dimensional Perovskites.

The insertion of large organic cations in metal halide perovskites with reduced-dimensional (RD) crystal structures increases crystal formation energy and regulates the growth orientation of the inorganic domains. However, the power conversion performance is curtailed by the insulating nature of the bulky cations. Now a series of RD perovskites with 2-thiophenmethylammonium (TMA) as the intercalating cation are investigated. Compared with traditional ligands, TMA demonstrates improved electron transfer in the inorganic framework. TMA modifies the near-band-edge integrity of the RD perovskite, improving hole transport. A power conversion efficiency of 19 % is achieved, the highest to date for TMA-based RD perovskite photovoltaics; these TMA devices provide a 12 % relative increase in PCE compared to control RD perovskite devices that use PEA as the intercalating ligand, a result of the improved charge transfer from the inorganic layer to the organic ligands.

Chinese medicine Tongxinluo capsule alleviates cerebral microcirculatory disturbances in ischemic stroke by modulating vascular endothelial function and inhibiting leukocyte-endothelial cell interactions in mice: A two-photon laser scanning microscopy study.

OBJECTIVE: The aim of this study was to examine the effect of TXL, a Chinese medicine prescription, on cerebral microcirculatory disturbances after pMCAO in mice using TPLSM and further explore the underlying mechanisms. METHODS: Adlut male C57BL/6J mice were subjected to pMCAO and orally administered with TXL (3.0, 1.5 and 0.75 g/kg/d) at 1, 3, and 21 hours after pMCAO. The following parameters were examined at 6 and 24 hours after pMCAO: neurological deficits, infarct volume, BBB permeability, cerebral microvessel structure, brain microcirculation (TPLSM imaging), vasoactive factors, and adhesion molecules. RESULTS: TXL improved neurological deficits, reduced infarct volume, attenuated BBB disruption, protected cerebral microvessel structure, increased cerebral capillary flow velocity and volume flux, and inhibited leukocyte-endothelial cell interactions at 6 or 24 hours after pMCAO. The therapeutic efficacy was exerted in a dose-dependent manner. Further study revealed that TXL (high dose) regulated the expression of PGI2, TXA2, and ET-1, and suppressed ICAM-1 and P-selectin. CONCLUSIONS: TXL alleviates cerebral microcirculatory disturbances against ischemic injury by modulating endothelial function and inhibiting leukocyte-endothelial cell interactions. These effects are associated with regulating the expression of PGI2, TXA2, and ET-1, and suppressing ICAM-1 and P-selectin expression.

Targeted therapy: resistance and re-sensitization.

The last two decades have witnessed a paradigm shift from cytotoxic drugs to targeted therapy in medical oncology and pharmaceutical innovation. Inspired by breakthroughs in molecular and cellular biology, a number of novel synthesized chemical compounds and recombinant antibodies have been developed to selectively target oncogenic signaling pathways in a broad array of tumor types. Although targeted therapeutic agents show impressive clinical efficacy and minimized adverse effects compared with traditional treatments, the challenging drug-resistant issue has also emerged to limit their benefits to cancer patients. In this regard, we aim to improve targeted therapy by presenting a systematic framework regarding the drug resistance mechanisms and alternative approaches to re-sensitize cancer cells/tissues therapeutically.

Suppression of lysosome function induces autophagy via a feedback down-regulation of MTOR complex 1 (MTORC1) activity.

Autophagy can be activated via MTORC1 down-regulation by amino acid deprivation and by certain chemicals such as rapamycin, torin, and niclosamide. Lysosome is the degrading machine for autophagy but has also been linked to MTORC1 activation through the Rag/RRAG GTPase pathway. This association raises the question of whether lysosome can be involved in the initiation of autophagy. Toward this end, we found that niclosamide, an MTORC1 inhibitor, was able to inhibit lysosome degradation and increase lysosomal permeability. Niclosamide was ineffective in inhibiting MTORC1 in cells expressing constitutively activated Rag proteins, suggesting that its inhibitory effects were targeted to the Rag-MTORC1 signaling system. This places niclosamide in the same category of bafilomycin A1 and concanamycin A, inhibitors of the vacuolar H(+)-ATPase, for its dependence on Rag GTPase in suppression of MTORC1. Surprisingly, classical lysosome inhibitors such as chloroquine, E64D, and pepstatin A were also able to inhibit MTORC1 in a Rag-dependent manner. These lysosome inhibitors were able to activate early autophagy events represented by ATG16L1 and ATG12 puncta formation. Our work established a link between the functional status of the lysosome in general to the Rag-MTORC1 signaling axis and autophagy activation. Thus, the lysosome is not only required for autophagic degradation but also affects autophagy activation. Lysosome inhibitors can have a dual effect in suppressing autophagy degradation and in initiating autophagy.

Transcriptomic Insights into Different Stimulation Intensity of Electroacupuncture in Treating COPD in Rat Models.

Background: Electroacupuncture (EA), with varying stimulation intensities, has demonstrated therapeutic potentials in both animal and clinical studies for the treatment of chronic obstructive pulmonary disease (COPD). However, a comprehensive investigation of the intensity-related effects, particularly 1mA and 3mA of EA, and the underlying mechanisms remains lacking. Methods: A COPD rat model was established by prolonged exposure to cigarette smoke and intermittent intratracheal instillation of lipopolysaccharide. EA treatment was administered at acupoints BL13 (Feishu) and ST36 (Zusanli), 20 minutes daily for 2 weeks, with intensities of 1mA and 3mA. EA effectiveness was evaluated by pulmonary function, histopathological change, serum level of inflammatory cytokines, and level of oxidative stress markers in serum and lung tissues. Transcriptome profiling and weighted gene co-expression network analysis (WGCNA) were performed to reveal gene expression patterns and identify hub genes. Real-time quantitative PCR (RT-qPCR) and Western blot (WB) were performed to detect the mRNA and protein expression levels, respectively. Results: EA at both 1mA and 3mA exerted differing therapeutic effects by improving lung function and reducing inflammation and oxidative stress in COPD rats. Transcriptome analysis revealed distinct expression patterns between the two groups, functionally corresponding to shared and intensity-specific (1mA and 3mA) enriched pathways. Eight candidate genes were identified, including Aqp9, Trem1, Mrc1, and Gpnmb that were downregulated by EA and upregulated in COPD. Notably, Msr1 and Slc26a4 exclusively downregulated in EA-1mA, while Pde3a and Bmp6 upregulated solely in EA-3mA. WGCNA constructed 5 key modules and elucidated the module-trait relationship, with the aforementioned 8 genes being highlighted. Additionally, their mRNA and protein levels were validated by RT-qPCR and WB. Conclusion: Our results demonstrated that 1mA and 3mA intensities induce distinct gene expression patterns at the transcriptional level, associated with shared and 1mA vs 3mA-specific enriched pathways. Genes Mrc1, Gpnmb, Trem1, and Aqp9 emerge as promising targets, and further studies are needed to elucidate their functional consequences in COPD.

Efficacy and Safety of Acupuncture in Managing COPD: An Overview of Systematic Reviews.

Background: Acupuncture has been used as an adjuvant therapy for Chronic obstructive pulmonary disease (COPD). However, systematic reviews (SRs) and meta-analyses (MAs) have reported inconsistent results and unknown quality. This overview aimed to summarize the current SRs/MAs to provide evidence for the effectiveness and safety of acupuncture in the treatment of COPD. Methods: SRs/MAs were searched via eight databases from their establishment to December 31, 2023. The methodological quality was assessed by A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2). The risk of bias was assessed using the Risk of Bias in Systematic Review (ROBIS) tool. The Preferred Reporting Items for Systematic Reviews and Meta-analyses for Acupuncture (PRISMA-A) to evaluate the reporting quality. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to determine the strength of evidence. In addition, we also conducted an analysis of the acupuncture points used in the primary RCTs. Results: Twenty-two SRs/MAs were included in this overview. Based on the assessment using AMSTAR 2, nineteen SRs/MAs were "critically low". Eight SRs/MAs had a low risk of bias. Based on PRISMA-A, the reporting completeness of eighteen SRs/MAs were more than 70%. As for GRADE assessment, only three outcome measures were of high quality. COPD patients can benefit from moxibustion, acupoint application, acupoint catgut embedding, manual acupuncture, and electroacupuncture, as indicated by effectiveness in measures including lung function, 6MWD, mMRC, CAT, and acute exacerbation. In addition, the efficacy of TENS needed to be further demonstrated. The commonly used acupuncture points in the RCTs include BL13, BL23, and EX-B1. Conclusion: Evidence from SRs showed that acupuncture is beneficial to lung function, acute exacerbation, 6MWD, mMRC and CAT. For SGRQ and brog scale, acupuncture should be used selectively, but this finding should still be taken with caution.

CCCP-Induced LC3 lipidation depends on Atg9 whereas FIP200/Atg13 and Beclin 1/Atg14 are dispensable.

Treatment of cells with carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial proton gradient uncoupler, can result in mitochondrial damage and autophagy activation, which in turn eliminates the injured mitochondria in a Parkin-dependent way. How CCCP mobilizes the autophagy machinery is not fully understood. By analyzing a key autophagy step, LC3 lipidation, we examined the roles of two kinase complexes typically involved in the initiation and nucleation phases of autophagy, namely the ULK kinase complex (UKC) and the Beclin 1/Atg14 complex. We found that CCCP-induced LC3 lipidation could be independent of Beclin 1 and Atg14. In addition, deletion or knockdown of the UKC component FIP200 or Atg13 only led to a partial reduction in LC3 lipidation, indicating that UKC could be also dispensable for this step during CCCP treatment. In contrast, Atg9, which is important for transporting vesicles to early autophagosomal structure, was required for CCCP-induced LC3 lipidation. Taken together, these data suggest that CCCP-induced autophagy and mitophagy depends more critically on Atg9 vesicles than on UKC and Beclin 1/Atg14 complex.

Untoward immune effects of modern medication.

Immune-related adverse events (irAEs) represent an increasingly concerning challenge in the assessment of biopharmaceutical products. In contrast to historically rare allergic reactions associated with small chemical drugs, contemporary biotherapeutics exhibit a significantly higher morbidity of irAEs, because of their complex structure and comprehensive mechanisms of action. While the immunogenicity of protein-based compounds is associated with the induction of anti-drug antibodies, the pathogenesis of irAEs in advanced biologics, such as cell and gene therapy, remains to be further delineated. In the current study, I present an updated profile regarding the untoward immune effects of medications, covering various material categories systematically, with the underlying mechanisms to inspire risk mitigation in biopharmaceutical development and application.

Insights into electronic properties of strained two-dimensional semiconductors by out-of-plane bending.

Strain engineering is an important strategy to modulate the electronic and optical properties of two-dimensional (2D) semiconductors. In experiments, an effective and feasible method to induce strains on 2D semiconductors is the out-of-plane bending. However, in contrast to the in-plane methods, it will generate a combined strain effect on 2D semiconductors, which deserves further explorations. In this work, we theoretically investigate the carrier transport-related electronic properties of arsenene, antimonene, phosphorene, and MoS2under the out-of-plane bending. The bending effect can be disassembled into the in-plane and out-of-plane rolling strains. We find that the rolling always degrades the transport performance, while the in-plane strain could boost carrier mobilities by restraining the intervalley scattering. In other words, pursuing the maximum in-plane strain at the expense of minimum rolling should be the primary strategy to promote transports in 2D semiconductors through bending. Electrons in 2D semiconductors usually suffer from the serious intervalley scattering caused by optical phonons. The in-plane strain can break the crystal symmetry and separate nonequivalent energy valleys at band edges energetically, confining carrier transports at the Brillouin zone Γ point and eliminating the intervalley scattering. Investigation results show that the arsenene and antimonene are suitable for the bending technology, because of their small layer thicknesses which can relieve the rolling burden. Their electron and hole mobilities can be doubled simultaneously, compared with their unstrained 2D structures. From this study, the rules for the out-of-plane bending technology towards promoting transport abilities in 2D semiconductors are obtained.

Global Research Trends on the Link Between the Microbiome and COPD: A Bibliometric Analysis.

Background: The pathogenesis of chronic obstructive pulmonary disease (COPD) has been studied in relation to the microbiome, providing space for more targeted interventions and new treatments. Numerous papers on the COPD microbiome have been reported in the last 10 years, yet few publications have used bibliometric methods to evaluate this area. Methods: We searched the Web of Science Core Collection for all original research articles in the field of COPD microbiome from January 2011 to August 2022 and used CiteSpace for visual analysis. Results: A total of 505 relevant publications were obtained, and the number of global publications in this field is steadily increasing every year, with China and the USA occupying the first two spots in international publications. Imperial College London and the University of Leicester produced the most publications. Brightling C from the UK was the most prolific writer, while Huang Y and Sze M from the USA were first and second among the authors cited. The American Journal of Respiratory and Critical Care Medicine had the highest frequency of citations. The top 10 institutions, cited authors and journals are mostly from the UK and the US. In the ranking of citations, the first article was a paper published by Sze M on changes in the lung tissue's microbiota in COPD patients. The keywords "exacerbation", "gut microbiota", "lung microbiome", "airway microbiome", "bacterial colonization", and "inflammation" were identified as cutting-edge research projects for 2011-2022. Conclusion: Based on the visualization results, in the future, we can use the gut-lung axis as the starting point to explore the immunoinflammatory mechanism of COPD, and study how to predict the effects of different treatments of COPD by identifying the microbiota, and how to achieve the optimal enrichment of beneficial bacteria and the optimal consumption of harmful bacteria to improve COPD.

Dopamine relieves inflammatory responses through the D2 receptor after electroacupuncture at ST36 in a mouse model of chronic obstructive pulmonary disease.

OBJECTIVE: To detect the role of dopamine in the anti-inflammatory effect of electroacupuncture (EA) at ST36 in a mouse model of chronic obstructive pulmonary disease (COPD). METHODS: Twenty-eight male BALB/c mice were randomly divided into the control group, model group, sham EA (sham) group or ST36 EA (ST36) group in a 1:1:1:1 ratio (n = 7 each). The COPD mouse model was established through cigarette smoke (CS) exposure for 12 weeks. During the last 2 weeks, EA was applied at a sham point location or ST36 before CS exposure. Lung function, histopathological changes, inflammatory cell counts in bronchoalveolar lavage fluid (BALF), inflammatory cytokines in BALF, plasma, lung tissue homogenate (LTH), and plasma dopamine levels were detected in the different groups. Furthermore, the role of different dopamine receptors was explored through intraperitoneal injections of non-specific dopamine receptor antagonist chlorpromazine, specific dopamine D1 receptor antagonist SCH 23390 and specific dopamine D2 receptor antagonist eticlopride hydrochloride prior to ST36 EA and CS exposure. RESULTS: EA at ST36 improved lung function, alleviated lung and systemic inflammatory responses by reducing inflammatory cells and cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-8 and IL-1ß in BALF, plasma and lung tissue in this COPD mouse model. Plasma dopamine was greatly increased after EA at ST36, negatively correlated with lung histological lesions and inflammatory cytokine levels, and positively correlated with mice body weight and lung function indicators. Chlorpromazine and eticlopride hydrochloride inhibited the anti-inflammatory effect of EA at ST36, while SCH 23390 showed no neutralizing effect. CONCLUSION: EA at ST36 could alleviate inflammation in this mouse model of COPD through the dopamine D2 receptor pathway.

Corrigendum: Circulating exosomal microRNA profiles in migraine patients receiving acupuncture treatment: a placebo-controlled clinical trial.

[This corrects the article DOI: 10.3389/fnmol.2022.1098766.].

Traditional Chinese medicine in treating ischemic stroke by modulating mitochondria: A comprehensive overview of experimental studies.

Ischemic stroke has been a prominent focus of scientific investigation owing to its high prevalence, complex pathogenesis, and difficulties in treatment. Mitochondria play an important role in cellular energy homeostasis and are involved in neuronal death following ischemic stroke. Hence, maintaining mitochondrial function is critical for neuronal survival and neurological improvement in ischemic stroke, and mitochondria are key therapeutic targets in cerebral stroke research. With the benefits of high efficacy, low cost, and high safety, traditional Chinese medicine (TCM) has great advantages in preventing and treating ischemic stroke. Accumulating studies have explored the effect of TCM in preventing and treating ischemic stroke from the perspective of regulating mitochondrial structure and function. In this review, we discuss the molecular mechanisms by which mitochondria are involved in ischemic stroke. Furthermore, we summarized the current advances in TCM in preventing and treating ischemic stroke by modulating mitochondria. We aimed to provide a new perspective and enlightenment for TCM in the prevention and treatment of ischemic stroke by modulating mitochondria.

Efficacy and safety of herbal medicine (Binafuxi granules) for the common cold with fever: A multicenter, randomized, double-blind, placebo-controlled, phase II clinical trial.

Background: Binafuxi granules are a traditional Uighur medicine (TUM) for treating the common cold with fever. However, high-quality clinical studies supporting its efficacy and safety are lacking. Methods: In this multicenter, randomized, double-blind, placebo-controlled, phase II clinical trial, patients with common cold and fever were randomly assigned to a high-dose group, low-dose group, and placebo group in a 1:1:1 ratio. Outcomes were time to fever relief, time to fever clearance, proportion of afebrile patients, time to symptom disappearance, rate of symptom disappearance, effective rate, emergency drug usage and safety assessment. Results: A total of 235 patients were recruited. Of these, 234 were included in the full analysis set (FAS), and 217 were included in the per-protocol set (PPS). In the FAS analysis, the median time to fever relief was 6.00 h, 5.54 h and 10.65 h (P = 0.31) in the high-dose group, low-dose group and placebo group, respectively. The median time to fever clearance was 18.29 h, 20.08 h and 25.00 h (P = 0.0018), respectively, and the proportion of afebrile patients was 92.4%, 89.7% and 71.4% (P = 0.0002), respectively. There was a significant difference in the disappearance time and disappearance rate of all symptoms and of individual symptoms. No serious adverse events were found. Conclusions: Binafuxi granules can dose-dependently shorten the fever course and improve clinical symptoms in patients suffering from the common cold with fever. Trial Registration: This trial was registered at Chinese Clinical Trial Registry (ChiCTR-IIR-17013379).

Real-world studies: bridging the gap between trial-assessed efficacy and routine care.

Even though randomized controlled clinical trials (RCTs) have been accepted as the gold standard for official assessment of novel interventions, there is a substantial gap between the efficacy observed in RCTs and the impact on clinical practice and in terms of patient benefit. While real-world studies (RWS) are emerging to confer valuable complementing evidence in this regard and beyond, the evolving role of RWS is yet to be agreed. This article delineates an updated profile of RWS covering effectiveness verification, rare adverse effects discovery, indication repurposing, to name a few. RWS tends not only to improve the efficiency of clinical investigations for regulatory approval, but also optimizes the whole-life cycle evaluation of biomedical/pharmaceutical products.

Eosinopenia as a biomarker for antibiotic use in COPD exacerbations: protocol for a retrospective hospital-based cohort study.

INTRODUCTION: The acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has a seriously negative impact on patients' healths condition and disease progression. Bacterial infection is closely related to AECOPD, and antibiotics are frequently used in clinical practice. The lack of specific biomarkers for rational antibiotics use always leads to antibiotics abuse in chronic obstructive pulmonary disease (COPD) flare-ups. Eosinopenia has been considered to be related to increased bacterial load of potentially pathogenic organisms at the onset of COPD exacerbations. Therefore, this study aims to investigate whether eosinopenia could be used as a reference for the use of antibiotics in AECOPD. METHODS AND ANALYSIS: In this study, a hospital-based retrospective cohort design will be adopted to analyse the clinical data of inpatients who are primarily diagnosed with AECOPD in West China Hospital of Sichuan University from 1 January 2010 to 31 December 2020. Relevant data will be extracted from the Clinical Big Data Platform for Scientific Research in West China Hospital, including demographic characteristics, blood eosinophil count, procalcitonin, C reactive protein, microbial cultivation, antibiotics use, length of hospital stay, non-invasive ventilation use, intensive care unit transfer and mortality, etc. The collected data will be described and inferred by corresponding statistical methods according to the data type and their distributions. Multiple binary logistic regression models will be used to analyse the relationship between blood eosinophil count and bacterial infection. The antibiotics use, and patient morbidity and mortality will be compared between patients with or without eosinopenia. ETHICS AND DISSEMINATION: This study has been approved by the Biomedical Ethics Review Board of West China Hospital of Sichuan University (Approval No. 2020-1056). And the research results will be published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ChiCTR2000039379.

Circulating exosomal microRNA profiles in migraine patients receiving acupuncture treatment: A placebo-controlled clinical trial.

Background: Acupuncture has a long history of being used in Chinese medicine for the treatment of migraine. However, molecular biomarkers for diagnosis and prognosis of migraine and its treatment are lacking. This study aimed to explore whether acupuncture could regulate differentially expressed exosomal miRNAs between patients with migraine without aura (MWoA) and healthy controls (HCs) and to identify diagnostic biomarkers that helped differentiate MWoA patients from HCs and identify prognostic biomarkers that helped to predict the effect of acupuncture. Methods: Here, we isolated serum exosomes from patients with MWoA and HCs before and after true and sham acupuncture treatment. Then, small RNA sequencing and bioinformatics analysis were performed to screen out key miRNAs specifically responding to acupuncture treatment. Pearson's correlation analysis was used to evaluate the correlation between miRNAs and clinical phenotypes. Finally, we applied a machine learning method to identify diagnostic biomarkers of MWoA patients and identify prognostic biomarkers that helped to predict the effect of acupuncture. Results: Small RNA sequencing identified 68 upregulated and 104 downregulated miRNAs in MWoA patients compared to those in HCs. Further, we identified eight upregulated and four downregulated miRNAs in migraine patients after true acupuncture treatment (trAMWoA), but not in the sham acupuncture treatment (shAMWoA) or HC group. Among them, has-miR-378a-5p was positively correlated with time unable to work, study, or do housework due to migraine (p < 0.05), whereas has-miR-605-3p was negatively correlated with the restrictive subscale of the migraine-specific quality of life questionnaire (MSQ) (p < 0.05). We then evaluated the diagnostic and prognostic potential of these 12 miRNAs in patients with MWoA. The combination of serum levels of exosomal has-miR-369-5p, has-miR-145-5p, and has-miR-5,010-3p could serve as diagnostic and prognostic biomarkers for MWoA patients following acupuncture treatment. Conclusion: This is the first study on the serum exosomal miRNA profiles of migraineurs before and after acupuncture treatment. Our results improve our understanding of the molecular functions of miRNAs in MWoA. More importantly, they expand our view of evaluating the clinical outcomes of migraine patients treated with acupuncture, using exosomal RNA markers. Clinical Trial Registration: Chinese Clinical Trial Registry, ChiCTR2000034417, July 2020.

A novel function of the human CLS1 in phosphatidylglycerol synthesis and remodeling.

Phosphatidylglycerol (PG) is a precursor for the biosynthesis of cardiolipin and a signaling molecule required for various cellular functions. PG is subjected to remodeling subsequent to its de novo biosynthesis in mitochondria to incorporate appropriate acyl content for its biological functions and to prevent the harmful effect of lysophosphatidylglycerol (LPG) accumulation. Yet, a gene encoding a mitochondrial LPG acyltransferase has not been identified. In this report, we identified a novel function of the human cardiolipin synthase (hCLS1) in regulating PG remodeling. In addition to the reported cardiolipin synthase activity, the recombinant hCLS1 protein expressed in COS-7 cells and Sf-9 insect cells exhibited a strong acyl-CoA-dependent LPG acyltransferase activity, which was further confirmed by purified hCLS1 protein overexpressed in Sf-9 cells. The recombinant hCLS1 displayed an acyl selectivity profile in the order of in the order of C18:1>C18:2>C18:0>C16:0, which is similar to that of hCLS1 toward PGs in cardiolipin synthesis, suggesting that the PG remodeling by hCLS1 is an intrinsic property of the enzyme. In contrast, no significant acyltransferase activity was detected from the recombinant hCLS1 enzyme toward lysocardiolipin which shares a similar structure with LPG. In support of a key function of hCLS1 in PG remodeling, overexpression of hCLS1 in COS-7 cells significantly increased PG biosynthesis concurrent with elevated levels of cardiolipin without any significant effects on the biosynthesis of other phospholipids. These results demonstrate for the first time that hCLS1 catalyzes two consecutive steps in cardiolipin biosynthesis by acylating LPG to PG and then converting PG to cardiolipin.

CD1d function is regulated by microsomal triglyceride transfer protein.

CD1d is a major histocompatibility complex (MHC) class I-related molecule that functions in glycolipid antigen presentation to distinct subsets of T cells that express natural killer receptors and an invariant T-cell receptor-alpha chain (invariant NKT cells). The acquisition of glycolipid antigens by CD1d occurs, in part, in endosomes through the function of resident lipid transfer proteins, namely saposins. Here we show that microsomal triglyceride transfer protein (MTP), a protein that resides in the endoplasmic reticulum of hepatocytes and intestinal epithelial cells (IECs) and is essential for lipidation of apolipoprotein B, associates with CD1d in hepatocytes. Hepatocytes from animals in which Mttp (the gene encoding MTP) has been conditionally deleted, and IECs in which Mttp gene products have been silenced, are unable to activate invariant NKT cells. Conditional deletion of the Mttp gene in hepatocytes is associated with a redistribution of CD1d expression, and Mttp-deleted mice are resistant to immunopathologies associated with invariant NKT cell-mediated hepatitis and colitis. These studies indicate that the CD1d-regulating function of MTP in the endoplasmic reticulum is complementary to that of the saposins in endosomes in vivo.