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Altered ceramide accumulation contributes to skeletal muscle insulin resistance, but mechanisms underlying fibre-type-specific susceptibility remain unclear. We hypothesized that fibre-type-specific ceramide metabolism governs vulnerability to lipid-induced insulin resistance. Lipidomics and quantification of ceramide-pathway enzymes were performed in mouse skeletal muscles with distinct fibre-type composition (oxidative, mixed and glycolytic) from control-diet (n = 12) and high-fat-diet (HFD; n = 12) mice. In humans, lipidomics and enzyme profiling were done in vastus lateralis biopsies from 36 adults stratified into oxidative or glycolytic phenotypes; insulin sensitivity was determined by glucose tolerance testing. siRNA-mediated silencing of SGMS1 and SGMS2 followed by lipidomics probed sphingomyelin–ceramide cycling in human myoblasts. In mouse muscle, ceramide composition rather than total content, differed by fibre type: oxidative muscle was enriched in very-long-chain ceramides, whereas glycolytic and mixed muscles contained higher C18-ceramides, paralleled by fibre-type-specific expression of enzymes involved in de novo synthesis and sphingomyelin–ceramide cycling. HFD induced ceramide remodelling, with C18-ceramides accumulating in oxidative and mixed muscles and very-long-chain species decreasing in glycolytic muscle; among all assessed enzymes, only SGMS2 was significantly downregulated in oxidative muscle. In humans, an oxidative phenotype associated with higher very-long-chain ceramides and insulin sensitivity, whereas a glycolytic phenotype displayed higher C16–18 ceramides, higher SGMS1 and SMPD2 expression, and lower insulin sensitivity. Elastic net regression identified C16–18 ceramides and galactosylceramides as negative predictors of insulin sensitivity. SGMS2 silencing caused broader ceramide accumulation than SGMS1 silencing, supporting a central role for SGMS2-mediated sphingomyelin–ceramide cycling in limiting ceramide burden.

Achieving the synergistic optimization among drug-loading capacity, targeting efficacy, and therapeutic potential persists as a critical challenge in the design and development of aptamer-drug conjugate (ApDC). Herein, an innovatively engineered tetra-armed trisubstituted benzene trimer-based linker incorporated multivalent moderately potent chemotherapeutic camptothecin (CPT) and site-specifically conjugated with the aptamer AS1411 to yield the tumor-microenvironment-responsive conjugate AS-CPT-4, self-assembling into well-defined nanoparticles (AS-CPT-4 NPs). The AS-CPT-4 NPs, endowing with dual active-passive targeting capabilities, manifested concurrent enhancement of tumor-specific accumulation and systemic safety profiles. Mechanistically, AS-CPT-4 NPs concurrently induced Topoisomerase I-mediated DNA lesion formation while abrogating CPT-induced NF-κB activation via AS1411-modulated IkK pathway inhibition. Interestingly, AS1411 was initially discovered in conjugates to reprogram the immunosuppressive tumor niche by augmenting CD8⁺ T cell infiltration while concomitantly depleting CD4⁺ T cell populations. In a colon carcinoma mouse model, AS-CPT-4 NPs abrogated off-target toxicity completely and achieved a potent 81.8 % tumor suppression rate, over double the efficacy of the clinically administered hydroxycamptothecin. This research achieved multifaceted enhancement of drug-loading capacity, targeting precision, and therapeutic outcomes through site-specific conjugation technology, thereby establishing a pioneering paradigm for expanding the therapeutic scope of moderately potent cytotoxic agents and overcoming the dual impediments of chemoresistance and immunosuppression.

Emissive carbon dots (CDs) that are synthesized from biomass can be highly sustainable, but the number of reported biomass-derived CDs that emit in the ultraviolet (UV) range is small. Moreover, current commercial UV-emitting materials rely heavily on the use of non-sustainable resources, such as rare metals, heavy metals, and petroleum chemicals. This yields that the development of efficient biomass-derived UV-CDs is desired. Here, we report on the hydrothermal conversion of a common green-tea extract (Polyphenon 60) into UV-CDs, which feature a photoluminescence (PL) peak wavelength of 384 nm, a full width at half maximum of 72 nm, and a photoluminescence quantum yield (PLQY) of 17% in water. By shifting to a lower-polarity solvent of 3-phenoxyanisole, the PLQY is strongly enhanced to 81%, and the PL peak blue-shifts to 370 nm, while the maximum solubility is lowered. These observations support the notion that the UV-CDs feature aggregation-induced emission and that they are endowed with hydrophilic surface groups. Moreover, the findings of excitation-wavelength-independent PL and a nanosecond-level short emission lifetime reveal that it is a single distinct fluorophore that produces the UV emission. We finally report preliminary results that the UV-CDs exhibit potential for inhibiting the proliferation of cancer cells.

Exercise has been shown to promote wound healing, including tendon repair. Myokines released from the exercised muscles are believed to play a significant role in this process. In our previous study, we used an in vitro coculture and loading model to demonstrate that 2% static loading of myoblasts increased the migration and proliferation of cocultured tenocytes─two crucial aspects of wound healing. IGF-1, released from myoblasts in response to 2% static loading, was identified as a contributor to the increased proliferation. However, the factors responsible for the enhanced migration remained unknown. In the current study, we subjected myoblasts in single culture conditions to 2, 5, and 10% static loading and performed proteomic analysis of the cell supernatants. Gene Ontology (GO) analysis revealed that 2% static loading induced the secretion of NBL1, C5, and EFEMP1, which is associated with cell migration and motility. Further investigation by adding exogenous recombinant proteins to human tenocytes showed that NBL1 increased tenocyte migration but not proliferation. This effect was not observed with treatments using C5 and EFEMP1.

The purpose of this study was to examine the nature of the underlying molecular mechanisms of cell death in human keratocytes treated with nigericin, a known pyroptosis inducer. Human keratocytes were exposed to nigericin, and cell death was assessed through morphological analysis and detection of related molecular markers. Proteomic profiling was performed to identify cell death-related proteins, with key findings validated by western blot. Additionally, organelle disruptions were examined using immunostaining techniques. Pyroptosis-like cell death was observed morphologically in cultured keratocytes. Moreover, an elevated release of IL-1beta was detected, accompanied by a significant loss of mitochondrial membrane potential. However, nigericin treatment induced a form of non-inflammatory cell death characterized by extensive vacuolation, resembling paraptosis. This was accompanied by the absence of caspase-3 activation and endoplasmic reticulum (ER) stress markers, along with increased accumulation of the autophagic marker LC3-II. Proteomic analysis revealed the absence of key components of the canonical pyroptosis pathway, including proteins involved in inflammasome assembly and the gasdermin (GSDM) family. These results were further confirmed by western blot. Significant alterations were also observed in the Golgi apparatus, mitochondria, and lysosomes following nigericin treatment. These findings suggest that nigericin triggers a paraptosis-like cell death in human keratocytes, rather than pyroptosis, as keratocytes lack the canonical executors of pyroptosis. This highlights an alternative mechanism of cell death in the cornea, warranting further exploration to understand its role and potential therapeutic implications.

Human amniotic membranes (hAMs) are widely used as wound management biomaterials, especially as grafts for corneal reconstruction due to the structure of the extracellular matrix and excellent biological properties. However, their fragile nature and rapid degradation rate hinder widespread clinical use. In this work, we engineered a novel self-powered electronic dress (E-dress), combining the beneficial properties of an amniotic membrane and a flexible electrical electrode to enhance wound healing. The E-dress displayed a sustained discharge capacity, leading to increased epidermal growth factor (EGF) release from amniotic mesenchymal interstitial stem cells. Live/dead staining, CCK-8, and scratch-wound-closure assays were performed in vitro. Compared with amniotic membrane treatment alone, the E-dress promoted cell proliferation and migration of mouse fibroblast cells and lower cytotoxicity. In a mouse full-skin defect model, the E-dress achieved significantly accelerated wound closure. Histological analysis revealed that E-dress treatment promoted epithelialization and neovascularization in mouse skin. The E-dress exhibited a desirable flexibility that aligned with tissue organization and displayed maximum bioactivity within a short period to overcome rapid degradation, implying great potential for clinical applications.

Keratocytes are the primary resident cells in the corneal stroma. They play an essential role in maintaining corneal physiological function. Studying the factors that affect the phenotype and behavior of keratocytes offers meaningful perspectives for improving the understanding and treatment of corneal injuries. In this study, 3% strain was applied to human keratocytes using the Flexcell® Tension Systems. Real-time quantitative PCR (RT-qPCR) and western blot were used to investigate the influence of strain on the expression of intracellular aldehyde dehydrogenase 3A1 (ALDH3A1). ALDH3A1 knockdown was achieved using double-stranded RNA-mediated interference (RNAi). Immunofluorescence (IF) staining was employed to observe the impact of changes in ALDH3A1 expression on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) nuclear translocation. Keratocyte proliferation and migration were assessed by bromodeoxyuridine (BrdU) assay and scratch wound healing assay, respectively. Mouse injury models and single-cell RNA sequencing of keratocytes from keratoconus patients were used to assess how strain influenced ALDH3A1 in vivo. Our results demonstrate that 3% strain suppresses keratocyte proliferation and increases ALDH3A1. Increased ALDH3A1 inhibits NF-κB nuclear translocation, a key step in the activation of the NF-κB signaling pathway. Conversely, ALDH3A1 knockdown promotes NF-κB nuclear translocation, ultimately enhancing keratocyte proliferation and migration. Elevated ALDH3A1 levels were also observed in mouse injury models with increased corneal strain and keratoconus patients. These findings provide valuable insights for further research into the role of corneal strain and its connection to corneal injury repair.

Skeletal muscle adaptation to exercise involves various phenotypic changes that enhance the metabolic and contractile functions. One key regulator of these adaptive responses is the activation of AMPK, which is influenced by exercise intensity. However, the mechanistic understanding of AMPK activation during exercise remains incomplete. In this study, we utilized an in vitro model to investigate the effects of mechanical loading on AMPK activation and its interaction with the mTOR signaling pathway. Proteomic analysis of muscle cells subjected to static loading (SL) revealed distinct quantitative protein alterations associated with RNA metabolism, with 10% SL inducing the most pronounced response compared to lower intensities of 5% and 2% as well as the control. Additionally, 10% SL suppressed RNA and protein synthesis while activating AMPK and inhibiting the mTOR pathway. We also found that SRSF2, necessary for pre-mRNA splicing, is regulated by AMPK and mTOR signaling, which, in turn, is regulated in an intensity-dependent manner by SL with the highest expression in 2% SL. Further examination showed that the ADP/ATP ratio was increased after 10% SL compared to the control and that SL induced changes in mitochondrial biogenesis. Furthermore, Seahorse assay results indicate that 10% SL enhances mitochondrial respiration. These findings provide novel insights into the cellular responses to mechanical loading and shed light on the intricate AMPK-mTOR regulatory network in muscle cells.

Podophyllotoxin (PPT), an aryltetralin-type lignan isolated from Podophyllum species, exhibits a wide range of biologic and pharmacologic activities, and mainly serves as an antiviral agent or antitumor drug in clinical applications. However, the therapeutic potential of PPT has been hindered due to its detrimental systemic toxicity, poor solubility, and bioavailability. Nanoparticles, which preferentially accumulate in tumors through enhanced permeability and retention effects, have become useful tools for targeted drug delivery, thus securing a niche in cancer therapies. The nano-based drug delivery platform has been introduced to PPT delivery for the purpose of improved solubility, enhanced efficacy, and reduced toxicity. For decades, extensive efforts have been dedicated to designing and developing various PPT delivery systems to mitigate undesirable toxicity and expand clinical applicability. Herein, we briefly review the latest achievements in PPT delivery patterns and pharmacodynamic concerns with the expectation of shedding light on future research and potential applications of PPT.

Exercise is widely recognized as beneficial for tendon healing. Recently, it has been described that muscle-derived molecules secreted in response to static exercise influence tendon healing. In this study, the optimal static loading intensity for tendon healing and the composition of secretome released by myoblasts in response to different intensities of static strain were investigated. In an in vitro coculture model, myoblasts were mechanically loaded using a Flexcell Tension System. Tenocytes were seeded on transwell inserts that allowed communication between the tenocytes and myoblasts without direct contact. Proliferation and migration assays, together with RNA sequencing, were used to determine potential cellular signaling pathways. The secretome from myoblasts exposed to 2% static loading increased the proliferation and migration of the cocultured tenocytes. RNA-seq analysis revealed that this loading condition upregulated the expression of numerous genes encoding secretory proteins, including insulin-like growth factor-1 (IGF-1). Confirmation of IGF-1 expression and secretion was carried out using qPCR and enzyme-linked immunosorbt assay (ELISA), revealing a statistically significant upregulation in response to 2% static loading in comparison to both control conditions and higher loading intensities of 5% and 10%. Addition of an inhibitor of the IGF-1 receptor (PQ401) to the tenocytes significantly reduced myoblast secretome-induced tenocyte proliferation. In conclusion, IGF-1 may be an important molecule in the statically loaded myoblast secretome, which is responsible for influencing tenocytes during exercise-induced healing.