Magnetic Nanocomposite Modified Hybrid Hole-Transport Layer for Constructing Organic Solar Cells with High Efficiencies.

An interface modification layer holds paramount significance in reducing interface carrier recombination and improving the ohmic contact between the active layer and the electrode in organic solar cells (OSCs). Modifying or doping the widely used hole-transport layer (HTL) PEDOT:PSS to adjust the work function, conductivity, and acidity has become a common strategy for achieving high-performance OSCs. Metal oxides and two-dimensional materials as secondary dopants into PEDOT:PSS, respectively, as well as a replacement of PEDOT:PSS both exhibit immense potential for achieving high-performance OSCs due to their excellent electrical properties. Herein, we report a method utilizing a Fe3O4/GO magnetic nanocomposite as a secondary dopant for PEDOT:PSS to modulate its inherent properties for constructing high-efficiency OSCs. The magnetic nanocomposite hybrid HTL exhibits a suitable optical transmittance and higher work function. Meanwhile, it is found that the addition of Fe3O4/GO magnetic nanoparticles expands the domain of PEDOT and enhances the phase separation between PEDOT and PSS segments, thereby improving the conductivity of PEDOT:PSS. By fine-tuning the doping ratio of a Fe3O4/GO magnetic nanocomposite in PEDOT:PSS, the best power conversion efficiency of OSCs based on PM6:L8-BO was up to 18.91%. The notable enhancement of the device's performance was due to the enhanced hole mobility and the improved charge extraction, further complemented by the decreased likelihood of interface recombination brought about by the hybrid HTL. Compared with PEDOT:PSS-based OSCs, an enhanced stability of the hybrid HTL-based device was also obtained. In addition, the diverse adaptability of the hybrid HTL was demonstrated in enhancing the performance of OSCs that are based on PM6:Y6 and PBDB-T:ITIC. The effectiveness and versatility of a magnetic nanocomposite hybrid HTL present opportunities for achieving high-performance OSCs.

Spatially resolved profiling of protein conformation and interactions by biocompatible chemical cross-linking in living cells.

Unlocking the intricacies of protein structures and interactions within the dynamic landscape of subcellular organelles presents a significant challenge. To address this, we introduce SPACX, a method for spatially resolved protein complex profiling via biocompatible chemical cross(x)-linking with subcellular isolation, designed to monitor protein conformation, interactions, and translocation in living cells. By rapidly capturing protein complexes in their native physiological state and efficiently enriching cross-linked peptides, SPACX allows comprehensive analysis of the protein interactome within living cells. Leveraging structure refinement with cross-linking restraints, we identify subcellular-specific conformation heterogeneity of PTEN, revealing dynamic differences in its dual specificity domains between the nucleus and cytoplasm. Furthermore, by discerning conformational disparities, we identify 83 cytoplasm-exclusive and 109 nucleus-exclusive PTEN-interacting proteins, each associated with distinct biological functions. Upon induction of ubiquitin-proteasome system stress, we observe dynamic alterations in PTEN assembly and its interacting partners during translocation. These changes, including the identification of components and interaction sites, are characterized using the SPACX approach. Notably, SPACX enables identification of unique interacting proteins specific to PTEN isoforms, including PTEN and PTEN-Long, through the determination of sequence-specific cross-linking interfaces. These findings underscore the potential of SPACX to elucidate the functional diversity of proteins within distinct subcellular sociology.

Electric Field Assisted Tangential Flow Filtration Device for Highly Effective Isolation of Bioactive Small Extracellular Vesicles from Cell Culture Medium.

Small extracellular vesicles (sEVs) are proven to hold great promise for diverse therapeutic and diagnostic applications. However, batch preparation of sEVs with high purity and bioactivity is a prerequisite for their clinical translations. Herein, we present an electric field assisted tangential flow filtration system (E-TFF), which integrates size-based filtration with electrophoretic migration-based separation to synergistically achieve the isolation of high-quality sEVs from cell culture medium. Compared with the gold-standard ultracentrifugation (UC) method, E-TFF not only improved the purity of sEVs by 1.4 times but also increased the yield of sEVs by 15.8 times. Additionally, the entire isolation process of E-TFF was completed within 1 h, about one-fourth of the time taken by UC. Furthermore, the biological activity of sEVs isolated by E-TFF was verified by co-incubation of sEVs derived from human umbilical cord mesenchymal stem cells (hUCMSCs) with HT22 mouse hippocampal neuronal cells exposed to amyloid-ß (Aß). The results demonstrated that the sEVs isolated by E-TFF exhibited a significant neuroprotective effect. Overall, the E-TFF platform provides a promising and robust strategy for batch preparation of high-quality sEVs, opening up a broad range of opportunities for cell-free therapy and precision medicine.

High-Performance PM6:Y6-Based Ternary Solar Cells with Enhanced Open Circuit Voltage and Balanced Mobilities via Doping a Wide-Band-Gap Amorphous Acceptor.

Great progress has been made in organic solar cells (OSCs) in recent years, especially after the report of the highly efficient small-molecule electron acceptor Y6. However, the relatively low open circuit voltage (VOC) and unbalanced charge mobilities remain two issues that need to be resolved for further improvement in the performance of OSCs. Herein, a wide-band-gap amorphous acceptor IO-4Cl, which possessed a shallower lowest unoccupied molecular orbital (LUMO) energy level than Y6, was introduced into the PM6:Y6 binary system to construct a ternary device. The mechanism study revealed that the introduced IO-4Cl was alloyed with Y6 to prevent the overaggregation of Y6 and offer dual channels for effective hole transportation, resulting in balanced hole and electron mobilities. Taking these advantages, an enhanced VOC of 0.894 V and an improved fill factor of 75.58% were achieved in the optimized PM6:Y6:IO-4Cl-based ternary device, yielding a promising power conversion efficiency (PCE) of 17.49%, which surpassed the 16.72% efficiency of the PM6:Y6 binary device. This work provides an alternative solution to balance the charge mobilities of PM6:Y6-based devices by incorporating an amorphous high-performance LUMO A-D-A small molecule as the third compound.

Ionic Liquid Gating Induces Anomalous Permeation through Membrane Channel Proteins.

Membrane channel proteins (MCPs) play key roles in matter transport through cell membranes and act as major targets for vaccines and drugs. For emerging ionic liquid (IL) drugs, a rational understanding of how ILs affect the structure and transport function of MCP is crucial to their design. In this work, GPU-accelerated microsecond-long molecular dynamics simulations were employed to investigate the modulating mechanism of ILs on MCP. Interestingly, ILs prefer to insert into the lipid bilayer and channel of aquaporin-2 (AQP2) but adsorb on the entrance of voltage-gated sodium channels (Nav). Molecular trajectory and free energy analysis reflect that ILs have a minimal impact on the structure of MCPs but significantly influence MCP functions. It demonstrates that ILs can decrease the overall energy barrier for water through AQP2 by 1.88 kcal/mol, whereas that for Na+ through Nav is increased by 1.70 kcal/mol. Consequently, the permeation rates of water and Na+ can be enhanced and reduced by at least 1 order of magnitude, respectively. Furthermore, an abnormal IL gating mechanism was proposed by combining the hydrophobic nature of MCP and confined water/ion coordination effects. More importantly, we performed experiments to confirm the influence of ILs on AQP2 in human cells and found that treatment with ILs significantly accelerated the changes in cell volume in response to altered external osmotic pressure. Overall, these quantitative results will not only deepen the understanding of IL-cell interactions but may also shed light on the rational design of drugs and disease diagnosis.

Tailoring the Molecular Planarity of Perylene Diimide-Based Third Component toward Efficient Ternary Organic Solar Cells.

Incorporating a third component into binary organic solar cells (b-OSCs) has provided a potential platform to boost power conversion efficiency (PCEs). However, gaining control over the non-equilibrium blend morphology via the molecular design of the perylene diimide (PDI)-based third component toward efficient ternary organic solar cells (t-OSCs) still remains challenging. Herein, two novel PDI derivatives are developed with tailored molecular planarity, namely ufBTz-2PDI and fBTz-2PDI, as the third component for t-OSCs. Notably, after performing a cyclization reaction, the twisted ufBTz-2PDI with an amorphous character transferred to the highly planar fBTz-2PDI followed by a semi-crystalline character. When incorporating the semi-crystalline fBTz-2PDI into the D18:L8-BO system, the resultant t-OSC achieved an impressive PCE of 18.56%, surpassing the 17.88% attained in b-OSCs. In comparison, the addition of amorphous ufBTz-2PDI into the binary system facilitates additional charge trap sites and results in a deteriorative PCE of 14.37%. Additionally, The third component fBTz-2PDI possesses a good generality in optimizing the PCEs of several b-OSCs systems are demonstrated. The results not only provided a novel A-DA'D-A motif for further designing efficient third component but also demonstrated the crucial role of modulated crystallinity of the PDI-based third component in optimizing PCEs of t-OSCs.

Terpolymer Containing a meta-Octyloxy-phenyl-Modified Dithieno[3,2-f:2',3'-h]quinoxaline Unit Enabling Efficient Organic Solar Cells.

With the rapid development of small-molecule electron acceptors, polymer electron donors are becoming more important than ever in organic photovoltaics, and there is still room for the currently available high-performance polymer donors. To further develop polymer donors with finely tunable structures to achieve better photovoltaic performances, random ternary copolymerization is a useful technique. Herein, by incorporating a new electron-withdrawing segment 2,3-bis(3-octyloxyphenyl)dithieno[3,2-f:2',3'-h]quinoxaline derivative (C12T-TQ) to PM6, a series of terpolymers were synthesized. It is worth noting that the introduction of the C12T-TQ unit can deepen the highest occupied molecular orbital energy levels of the resultant polymers. In addition, the polymer Z6 with a 10% C12T-TQ ratio possesses the highest film absorption coefficient (9.86 × 104 cm-1) among the four polymers. When blended with Y6, it exhibited superior miscibility and mutual crystallinity enhancement between Z6 and Y6, suppressed recombination, better exciton separation and charge collection characteristics, and faster hole transfer in the D-A interface. Consequently, the device of Z6:Y6 successfully achieved enhanced photovoltaic parameters and yielded an efficiency of 17.01%, higher than the 16.18% of the PM6:Y6 device, demonstrating the effectiveness of the meta-octyloxy-phenyl-modified dithieno[3,2-f:2',3'-h]quinoxaline moiety to build promising terpolymer donors for high-performance organic solar cells.

Metal organic layers enabled cell surface engineering coupling biomembrane fusion for dynamic membrane proteome profiling.

Systematically dissecting the highly dynamic and tightly communicating membrane proteome of living cells is essential for the system-level understanding of fundamental cellular processes and intricate relationship between membrane-bound organelles constructed through membrane traffic. While extensive efforts have been made to enrich membrane proteins, their comprehensive analysis with high selectivity and deep coverage remains a challenge, especially at the living cell state. To address this problem, we developed the cell surface engineering coupling biomembrane fusion method to map the whole membrane proteome from the plasma membrane to various organelle membranes taking advantage of the exquisite interaction between two-dimensional metal-organic layers and phospholipid bilayers on the membrane. This approach, which bypassed conventional biochemical fractionation and ultracentrifugation, facilitated the enrichment of membrane proteins in their native phospholipid bilayer environment, helping to map the membrane proteome with a specificity of 77% and realizing the deep coverage of the HeLa membrane proteome (5087 membrane proteins). Furthermore, membrane N-phosphoproteome was profiled by integrating the N-phosphoproteome analysis strategy, and the dynamic membrane proteome during apoptosis was deciphered in combination with quantitative proteomics. The features of membrane protein N-phosphorylation modifications and many differential proteins during apoptosis associated with mitochondrial dynamics and ER homeostasis were found. The method provided a simple and robust strategy for efficient analysis of membrane proteome, offered a reliable platform for research on membrane-related cell dynamic events and expanded the application of metal-organic layers.

On-capillary alkylation micro-reactor: a facile strategy for proteo-metabolome profiling in the same single cells.

Single-cell multi-omics analysis can provide comprehensive insights to study cell-to-cell heterogeneity in normal and disease physiology. However, due to the lack of amplification technique, the measurement of proteome and metabolome in the same cell is challenging. Herein, a novel on-capillary alkylation micro-reactor (OCAM) was developed to achieve proteo-metabolome profiling in the same single cells, by which proteins were first covalently bound to an iodoacetic acid functionalized open-tubular capillary micro-reactor via sulfhydryl alkylation reaction, and metabolites were rapidly eluted, followed by on-column digestion of captured proteins. Compared with existing methods for low-input proteome sample preparation, OCAM exhibited improved efficiency, anti-interference ability and recovery, enabling the identification of an average of 1509 protein groups in single HeLa cells. This strategy was applied to single-cell proteo-metabolome analysis of mouse oocytes at different stages, 3457 protein groups and 171 metabolites were identified in single oocytes, which is the deepest coverage of proteome and metabolome from single mouse oocytes to date, achieving complementary characterization of metabolic patterns during oocyte maturation.

Development of nanozymes for promising alleviation of COVID-19-associated arthritis.

The COVID-19 pandemic caused by SARS-CoV-2 has been identified as a culprit in the development of a variety of disorders, including arthritis. Although the emergence of arthritis following SARS-CoV-2 infection may not be immediately discernible, its underlying pathogenesis is likely to involve a complex interplay of infections, oxidative stress, immune responses, abnormal production of inflammatory factors, cellular destruction, etc. Fortunately, recent advancements in nanozymes with enzyme-like activities have shown potent antiviral effects and the ability to inhibit oxidative stress and cytokines and provide immunotherapeutic effects while also safeguarding diverse cell populations. These adaptable nanozymes have already exhibited efficacy in treating common types of arthritis, and their distinctive synergistic therapeutic effects offer great potential in the fight against arthritis associated with COVID-19. In this comprehensive review, we explore the potential of nanozymes in alleviating arthritis following SARS-CoV-2 infection by neutralizing the underlying factors associated with the disease. We also provide a detailed analysis of the common therapeutic pathways employed by these nanozymes and offer insights into how they can be further optimized to effectively address COVID-19-associated arthritis.

Performance and mechanism of Pb2+ and Cd2+ ions' adsorption via modified antibiotic residue-based hydrochar.

This study investigated the hydrochar-based porous carbon prepared by combining the technical route of hydrothermal carbonization (HTC) + chemical activation. The hydrochar morphology was adjusted by changing the activation reaction conditions and adding metal salts. Experiments showed that the activation of KHCO3 significantly increased the specific surface area and pore size of the hydrochar. Besides, oxygen-rich groups on the surface of the activated hydrochar interacted with heavy metal ions to achieve efficient adsorption. The activated hydrothermal carbon adsorption capacity for Pb2+ and Cd2+ ions reached 289 and 186 mg/g, respectively. The adsorption mechanism study indicated that the adsorption of Pb2+ and Cd2+ was related to electrostatic attraction, ion exchange, and complexation reactions. The "HTC + chemical activation" technology was environmentally friendly and effectively implemented antibiotic residues. Carbon materials with high adsorption capacity can be prepared so that biomass resources can be utilized with excessive value, as a consequence presenting technical assistance for the comprehensive disposal of organic waste in the pharmaceutical industry and establishing a green and clean production system.

Enhancing Top-Down Characterization of Membrane Proteoforms with C8-Functional Amine-Bridged Hybrid Monoliths.

Comprehensive characterization of membrane proteins at the level of proteoforms in complex biological samples by top-down mass spectrometry (MS) is of vital importance in revealing their precise functions. However, severe peak broadening in the separation of hydrophobic membrane proteins, caused by resistance to mass transfer and strong adsorption on separation materials, leads to MS spectra overlap and signal suppression, which makes against the in-depth research on membrane proteoforms. Herein, C8-functional amine-bridged hybrid monoliths with an interconnected macroporous structure were developed by the in situ one-step sol-gel reaction of triethoxy(octyl)silane and bis[3-(trimethoxysilyl)propyl]amine in capillaries. Due to the unique macroporous structure and bridged secondary amino groups in the framework, the monolith possessed reduced resistance to mass transfer, low nonspecific adsorption, and electrostatic repulsion to membrane proteins. These features tremendously alleviated peak broadening in the separation of membrane proteins, thus outperforming traditional reversed-phase columns in top-down characterization of membrane proteoforms. With this monolith, a total of 3100 membrane proteoforms were identified in the mouse hippocampus, representing the largest membrane proteoform database obtained by top-down analysis so far. The identified membrane proteoforms revealed abundant information, including combinatorial post-translational modifications (PTMs), truncation, and transmembrane domains. Furthermore, the proteoform information was integrated into the interaction network of membrane protein complexes involved in oxidative phosphorylation processing, opening up new opportunities to uncover more detailed molecular basis and interaction in the biological processes.

Antibody-free approach for ubiquitination profiling by selectively clicking the ubiquitination sites.

Ubiquitination is a reversible post-translational modification that plays a pivotal role in numerous biological processes. Antibody-based approaches, as the most used methods for identifying ubiquitination sites, exist sequence recognition bias, high cost, and ubiquitin-like protein modification interference, limiting their widespread application. Here, we proposed an Antibody-Free approach for Ubiquitination Profiling, termed AFUP, by selectively clicking the ubiquitinated lysine to enrich and profile endogenous ubiquitinated peptides using mass spectrometry. Briefly, protein amines were blocked with formaldehyde, and then the ubiquitin molecules were hydrolyzed from the ubiquitinated proteins by non-specific deubiquitinases USP2 and USP21 to release the free ε-amine of lysine. Peptides containing free ε-amines were selectively enriched with streptavidin beads upon NHS-SS-biotin labeling. Finally, the enriched peptides were eluted by DTT and analyzed by LC-MS/MS, resulting in ubiquitination profiling. Preliminary experiment showed that 349 ± 7 ubiquitination sites were identified in 0.8 mg HeLa lysates with excellent reproducibility (CV = 2%) and high quantitative stability (Pearson, r ≥ 0.91) using our method. With the combination of AFUP and simple basic C18 pre-fractionation, approximately 4000 ubiquitination sites were identified in a single run of 293T cells. In addition, we showed that 209 ubiquitination sites were significantly regulated in UBE2O knockdown cells after normalized to protein abundance. In conclusion, our results demonstrated that AFUP is a robust alternative strategy for ubiquitomics research.

Systematical analysis of sludge treatment and disposal technologies for carbon footprint reduction.

This study aims to comprehensively analyze the Greenhouse Gases (GHGs) emissions from current sewage sludge treatment and disposal technologies (building material, landfill, land spreading, anaerobic digestion, and thermochemical processes) based on the database of Science Citation Index (SCI) and Social Science Citation Index (SSCI) from 1998 to 2020. The general patterns, spatial distribution, and hotspots were provided by bibliometric analysis. A comparative quantitative analysis based on life cycle assessment (LCA) put forward the current emission situation and the key influencing factors of different technologies. The effective GHG emissions reduction methods were proposed to mitigate climate change. Results showed that incineration or building materials manufacturing of highly dewatered sludge, and land spreading after anaerobic digestion have the best GHG emissions reduction benefits. Biological treatment technologies and thermochemical processes have great potential for reducing GHGs. Enhancement of pretreatment effect, co-digestion, and new technologies (e.g., injection of carbon dioxide, directional acidification) are major approaches to facilitate substitution emissions in sludge anaerobic digestion. The relationship between the quality and efficiency of secondary energy in thermochemical process and GHGs emission still needs further study. Solid sludge products generated by bio-stabilization or thermochemical processes are considered to have a certain carbon sequestration value and can improve the soil environment to control GHG emissions. The findings are useful for future development and processes selection of sludge treatment and disposal facing carbon footprint reduction.

Pushpin-like nanozyme for plasmon-enhanced tumor targeted therapy.

Relatively low catalytic activity and poor targeting limit the applications of nanoceria (CeO2) nanozymes in the treatment of tumors. Here, we designed a unique pushpin-like Au/CeO2 hybrid nanozyme with high catalytic activity by combining site-selective growth and steric restriction strategies. The enhanced enzyme activity was attributed to plasmon-induced hot electrons. Furthermore, the pushpin-like structure facilitated targeting molecule modification. The nanozyme exhibited superior antitumor effects both in vitro and in vivo due to its high catalytic activity and targeting effects. Importantly, its potential mechanism of anti-tumor therapy was studied by quantitative proteomics. The reactive oxygen species (ROS) generated by folic acid-PEG thiol-Au/CeO2 (FA-Au/CeO2) caused mitochondrial and proteasomal damage in tumor cells and further evoked a response to oxidative stress and innate immunity in vivo. This study provided a spatiotemporal approach to enhance the antitumor activity of nanozymes by structural design. The designed pushpin-like Au/CeO2 could be utilized as a multifunctional nanoplatform for in vitro and in vivo plasmon-enhanced cancer therapy with active targeting effects. Moreover, this study systematically explored the anti-tumor mechanism of the nanozyme in both cell and mouse models, promoting its translation to the clinic. STATEMENT OF SIGNIFICANCE: A strategy combining the principles of site-selective growth and steric restriction was developed to prepare a unique pushpin-like Au/CeO2 hybrid nanozyme with high catalytic activity and low steric hindrance. The hybrid nanozyme showed superior antitumor activity at both the cellular and tissue levels. Furthermore, the antitumor mechanism was investigated in terms of the differential proteins and their pathways using quantitative proteomics, thus promoting the translation of nanozymes to the clinic.

Efficient Enrichment Method for N-Phosphorylation Peptides in Mouse Brain Tissue.

In addition to O-phosphorylation, protein N-phosphorylation was proven to play important roles in multiple biological processes. Although affinity methods were developed for the enrichment of N-phosphorylation peptides in cells, it was still difficult to enrich N-phosphorylation peptides in tissue due to its complexity. In this study, we established a workflow for the identification of N-phosphorylation peptides in mouse brain tissue by direct enrichment in high concentration urea. In total, 989 N-phosphorylation sites were obtained using 0.5 M urea as enrichment buffer. Among all identified N-phosphorylation sites, the localization probability over 0.75 was as high as 80%, suggesting the reliability of the method. Furthermore, the sequence motif analysis and gene ontology analysis results showed a good match to previous studies. The method was successfully used for N-phosphorylation analysis of mouse hippocampus from Alzheimer's disease model, and 533 N-phosphorylation sites were identified in 5 × FAD mouse hippocampus tissue. Biological process analysis results showed that "brain development", "cellular response to reactive oxygen species", "microtubule cytoskeleton organization", and "peptidyl-serine phosphorylation" were especially enriched in 5 × FAD mouse. It is suggested that N-phosphorylation may be related to Alzheimer's disease in these aspects.

Nogo-B receptor increases glycolysis and the paclitaxel resistance of estrogen receptor-positive breast cancer via the HIF-1α-dependent pathway.

Chemotherapy can improve the prognosis and overall survival of breast cancer patients, but chemoresistance continues a major problem in clinical. Most breast cancer is estrogen receptor (ER) positive but responds less to neoadjuvant or adjuvant chemotherapy than ER-negative breast cancer. The Nogo-B receptor (NgBR) increases the chemoresistance of ER-positive breast cancer by facilitating oncogene signaling pathways. Here, we further investigated the potential role of NgBR as a novel target to overcome glycolysis-dependent paclitaxel resistance in ER-positive breast cancer. NgBR knockdown inhibited glycolysis and promoted paclitaxel-induced apoptosis by attenuating HIF-1α expression in ER-positive breast cancer cells via NgBR-mediated estrogen receptor alpha (ERα)/hypoxia-inducible factor-1 alpha (HIF-1α) and nuclear factor-kappa B subunit (NF-κB)/HIF-1α signaling pathways. A ChIP assay further confirmed that NgBR overexpression not only facilitates ERα binding to HIF-1α and GLUT1 genes but also promotes HIF-1α binding to GLUT1, HK2, and LDHA genes, which further promotes glycolysis and induces paclitaxel resistance. In conclusion, our study suggests that NgBR expression is essential for maintaining the metabolism and paclitaxel resistance of ER-positive breast cancer, and the NgBR can be a new therapeutic target for improving chemoresistance in ER-positive breast cancer.

AKR1C3-dependent lipid droplet formation confers hepatocellular carcinoma cell adaptability to targeted therapy.

Rationale: Increased lipid droplet (LD) formation has been linked to tumor metastasis, stemness, and chemoresistance in various types of cancer. Here, we revealed that LD formation is critical for the adaptation to sorafenib in hepatocellular carcinoma (HCC) cells. We aim to investigate the LD function and its regulatory mechanisms in HCC. Methods: The key proteins responsible for LD formation were screened by both metabolomics and proteomics in sorafenib-resistant HCC cells and further validated by immunoblotting and immunofluorescence staining. Biological function of AKR1C3 was evaluated by CRISPR/Cas9-based gene editing. Isotopic tracing analysis with deuterium3-labeled palmitate or carbon13-labeled glucose was conducted to investigate fatty acid (FA) and glucose carbon flux. Seahorse analysis was performed to assess the glycolytic flux and mitochondrial function. Selective AKR1C3 inhibitors were used to evaluate the effect of AKR1C3 inhibition on HCC tumor growth and induction of autophagy. Results: We found that long-term sorafenib treatment impairs fatty acid oxidation (FAO), leading to LD accumulation in HCC cells. Using multi-omics analysis in cultured HCC cells, we identified that aldo-keto reductase AKR1C3 is responsible for LD accumulation in HCC. Genetic loss of AKR1C3 fully depletes LD contents, navigating FA flux to phospholipids, sphingolipids, and mitochondria. Furthermore, we found that AKR1C3-dependent LD accumulation is required for mitigating sorafenib-induced mitochondrial lipotoxicity and dysfunction. Pharmacologic inhibition of AKR1C3 activity instantly induces autophagy-dependent LD catabolism, resulting in mitochondrial fission and apoptosis in sorafenib-resistant HCC clones. Notably, manipulation of AKR1C3 expression is sufficient to drive the metabolic switch between FAO and glycolysis. Conclusions: Our findings revealed that AKR1C3-dependent LD formation is critical for the adaptation to sorafenib in HCC through regulating lipid and energy homeostasis. AKR1C3-dependent LD accumulation protects HCC cells from sorafenib-induced mitochondrial lipotoxicity by regulating lipophagy. Targeting AKR1C3 might be a promising therapeutic strategy for HCC tumors.

A photo-oxidation driven proximity labeling strategy enables profiling of mitochondrial proteome dynamics in living cells.

Mapping the proteomic landscape of mitochondria with spatiotemporal precision plays a pivotal role in elucidating the delicate biological functions and complex relationship with other organelles in a variety of dynamic physiological processes which necessitates efficient and controllable chemical tools. We herein report a photo-oxidation driven proximity labeling strategy to profile the mitochondrial proteome by light dependence in living cells with high spatiotemporal resolution. Taking advantage of organelle-localizable organic photoactivated probes generating reactive species and nucleophilic substrates for proximal protein oxidation and trapping, mitochondrial proteins were selectively labeled by spatially limited reactions in their native environment. Integration of photo-oxidation driven proximity labeling and quantitative proteomics facilitated the plotting of the mitochondrial proteome in which up to 310 mitochondrial proteins were identified with a specificity of 64% in HeLa cells. Furthermore, mitochondrial proteome dynamics was deciphered in drug resistant Huh7 and LPS stimulated HMC3 cells which were hard-to-transfect. A number of differential proteins were quantified which were intimately linked to critical processes and provided insights into the related molecular mechanisms of drug resistance and neuroinflammation in the perspective of mitochondria. The photo-oxidation driven proximity labeling strategy offers solid technical support to a highly precise proteomic platform in time and finer space for more knowledge of subcellular biology.