Cellular and Molecular Life Sciences最新文献

Aging-related sarcopenia represents a significant health concern due to its impact on the quality of life in the elderly. This study elucidates the molecular mechanisms underlying sarcopenia by employing single-cell sequencing and public transcriptome databases to compare young and aged mouse skeletal muscles. Cellular classification and pseudotime analyses differentiated cell types and their interrelationships, revealing a marked reduction in satellite cell numbers and a consistent upregulation of TXNIP (Thioredoxin interacting protein) across various muscle cell populations in aged mice. Further transcriptomic data integration and batch correction from the GEO (Gene Expression Omnibus) database highlighted key differentially expressed genes. The role of TXNIP and its transcriptional regulation by FOXO1 (Forkhead box O1) was confirmed through in vitro experiments, which demonstrated FOXO1's influence on TXNIP expression and its subsequent suppression of glutathione metabolism, leading to satellite cell ferroptosis. Additionally, in vivo studies showed that overexpression of TXNIP in young mice's muscle tissues significantly reduced muscle mass, suggesting its potential role in the initiation of sarcopenia. Our findings suggest that FOXO1-mediated regulation of TXNIP and the disruption of glutathione metabolism are central to the process of sarcopenia, offering new insights into its pathogenesis.

Liquid-liquid phase separation (LLPS), driven by dynamic, low-affinity multivalent interactions of proteins and RNA, results in the formation of macromolecular condensates on chromatin. These structures are likely to provide high local concentrations of effector factors responsible for various processes including transcriptional regulation and DNA repair. In particular, enhancers, super-enhancers, and promoters serve as platforms for condensate assembly. In the current paradigm, enhancer-promoter (EP) interaction could be interpreted as a result of enhancer- and promoter-based condensate contact/fusion. There is increasing evidence that the spatial juxtaposition of enhancers and promoters could be provided by loop extrusion (LE) by SMC complexes. Here, we propose that condensates may act as barriers to LE, thereby contributing to various nuclear processes including spatial contacts between regulatory genomic elements.

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial pneumonia, with increasing incidence and prevalence. One of the cellular characteristics is the differentiation of fibroblasts to myofibroblasts. However, the metabolic-related signaling pathway regulated by circular RNAs (circRNAs) during this process remains unclear. Here, we demonstrated that circ0066187 promoted fibroblast-to-myofibroblast differentiation by metabolic-related signaling pathway. Mechanism analysis research identified that circ0066187 directly targeted signal transducer and activator of transcription 3 (STAT3)-mediated metabolism signal pathway to enhance fibroblast-to-myofibroblast differentiation by sponging miR-29b-2-5p, resulting in pulmonary fibrosis. Integrative multi-omics analysis of metabolomics and proteomics revealed three pathways co-enriched in proteomics and metabolomics, namely, Protein digestion and absorption, PI3K-Akt signaling pathway, and FoxO signaling pathway. In these three signaling pathways, seven differentially expressed metabolites such as L-glutamine, L-proline, adenosine monophosphate (AMP), L-arginine, L-phenylalanine, L-lysine and L-tryptophan, and six differentially expressed proteins containing dipeptidyl peptidase-4 (DPP4), cyclin D1 (CCND1), cyclin-dependent kinase 2 (CDK2), fibroblast growth factor 2 (FGF2), collagen type VI alpha 1 (COL6A1) and superoxide dismutase 2 (SOD2) were co-enriched. Gain-and loss-of-function studies and rescue experiments were performed to verify that circ0066187 promoted STAT3 expression by inhibiting miR-29b-2-5p expression to control the above metabolites and proteins. As a result, these metabolites and proteins provided the material basis and energy requirements for the progression of pulmonary fibrosis. In conclusion, circ0066187 can function as a profibrotic metabolism-related factor, and interference with circ0066187 can prevent pulmonary fibrosis. The finding supported that circ0066187 can be a metabolism-related therapeutic target for IPF treatment.

Pancreatic cancer (PCa) has insidious onset, high malignancy and poor prognosis. Gemcitabine (GEM) is one of the first-line chemotherapy drugs for PCa. However, GEM resistance has always been a bottleneck problem leading to recurrence and death of PCa patients. RNA-binding proteins (RBPs) are important proteins that regulate transportation, splicing, stability and translation of RNA. Abnormal expression of RBPs often lead to a series of abnormal accumulation or degradation of downstream RNA resulting in various diseases. In our study, we utilized RIP seq, RIP-qPCR, in vitro and in vivo experiments and found that pumilio2 (PUM2) was high expression in PCa, and promoted GEM resistance of PCa by regulating mRNA stability of integrin Alpha 3 (ITGA3) and other genes in focal adhesion pathway, and there was positive feedback regulation between PUM2 and transcription factor early growth response gene 1 (EGR1), that is PUM2 binding to 3'UTR region of EGR1 mRNA, and EGR1 binding to promoter region of PUM2 gene. The discovery of EGR1/PUM2/ITGA3 axis provided a solid experimental basis for the selection of chemotherapy regiments for PCa patients and exploration of combined regimens to reverse GEM resistance in the future.

All cellular transcripts initially have a tri-phosphate (PPP) group at the 5'-end, recognized as a pathogen-associated molecular pattern (PAMP) by a cell's innate immune system. The removal of 5'-PPP occurs to varying extents, causing immune imbalance. However, how cells manage this situation has not yet been documented. Among 5'-PPP removal mechanisms, recent attention has been towards an RNA phosphatase called Dual Specificity Phosphatase 11 (DUSP11), which acts preferentially on 5'-triphosphorylated (5'-PPP) RNAs transcribed by RNA polymerase III (Pol III) and converts them to a 5'-monophosphorylated (5'-P) form. Here we have elucidated that immune imbalance caused by variable DUSP11 expression in human is controlled by a Pol III-transcribed non-coding RNA (Pol III-ncRNA), nc886. DUSP11 depletion leads to the accumulation of 5'-PPP-Pol III-ncRNAs, making cells respond better to incoming PAMP. Distinctly from other Pol III-ncRNAs, DUSP11 depletion increases the expression of nc886 in a 5'-P form, which mitigates the sensitized immunity. nc886 expression is also increased by infection with Kaposi's sarcoma-associated herpesvirus (KSHV) that suppresses DUSP11, and, in turn, nc886 stimulates KSHV infectivity. DUSP11 levels in normal tissues are relatively constitutive in mice lacking nc886 but are variable in humans. This wide range of DUSP11 expression and the resultant immune imbalance is probably adjusted by nc886. In summary, our study of DUSP11 and nc886 has uncovered a novel mechanism by which human cells control immune sensitivity, which is intrinsically caused by cellular RNA metabolism, allowing different states of equilibrium between immune status and gene expression.

Proteinopathies, such as amyotrophic lateral sclerosis (ALS), are marked by the accumulation of misfolded proteins that disrupt cellular processes. Eukaryotic cells have developed protein quality control systems to eliminate these aberrant proteins, but these systems often fail to differentiate between normal and misfolded proteins. In ALS, pathological inclusions primarily composed of misfolded TDP-43 are a hallmark of the disease. Recently, a novel unconventional secretion process called misfolding-associated protein secretion (MAPS) has been discovered to selectively export misfolded proteins. USP19, an Endoplasmic Reticulum-associated ubiquitin peptidase, plays a crucial role in this process. In this study, we investigated the impact of ER-anchored USP19 on the secretion of misfolded TDP-43. Here we found that USP19 overexpression significantly promotes the secretion of soluble and aggregated misfolded TDP-43, requiring both ER anchoring and ubiquitin peptidase activity. Characterization of the cellular and molecular mechanisms involved in this process highlighted the importance of early autophagosomal and late endosomal/amphisomal compartments, while lysosomes did not play a key role. By using dominant-negative mutants and small interfering RNAs, we identified that USP19-mediated secretion of misfolded TDP-43 is modulated by key factors involved in cellular trafficking and secretion pathways, such as ATG7, the ESCRT-O HGS/HRS, the Rab GTPases RAB11A, RAB8A, and RAB27A, and the v-SNARE VAMP7. We also confirmed the crucial role of the DNAJC5/CSPα cochaperone. Overall, this study provides new insights into how cells manage the secretion of misfolded TDP-43 proteins and potentially opens new avenues for therapeutic interventions in ALS and related disorders.

Influenza viruses still represent a great concern for Public Health by causing yearly seasonal epidemics and occasionally worldwide pandemics. Moreover, spillover events at the animal-human interface are becoming more frequent nowadays, also involving animal species not previously found as reservoirs. To restrict the effects of influenza virus epidemics, especially in at-risk population, and to prepare a drug arsenal for possible future pandemics, researchers worldwide have been working on the development of antiviral strategies since the 80's of the last century. One of the main obstacles is the considerable genomic variability of influenza viruses, which constantly poses the issues of drug-resistance emergence and immune evasion. This review summarizes the approved therapeutics for clinical management of influenza, promising new anti-flu compounds and monoclonal antibodies currently undergoing clinical evaluation, and molecules with efficacy against influenza virus in preclinical studies. Moreover, we discuss some innovative anti-influenza therapeutic approaches such as combination therapies and targeted protein degradation. Given the limited number of drugs approved for influenza treatment, there is a still strong need for novel potent anti-influenza drugs endowed with a high barrier to drug resistance and broad-spectrum activity against influenza viruses of animal origin that may be responsible of future large outbreaks and pandemics.

Skin infiltration by neutrophils is a hallmark of the chronic inflammatory skin disease psoriasis, yet the mechanisms underlying neutrophil recruitment and positioning in chronically inflamed skin remain poorly understood. In this study, we demonstrate the significant impact of a total genetic deficiency of secretory leukocyte protease inhibitor (SLPI) on neutrophil migration in mouse skin. Without SLPI, neutrophils displayed an unconventional migratory pattern, characterized by altered interactions with vessel walls and reduced efficiency in extravasating from blood vessels into skin tissue during the early stages of experimental psoriasis. This was associated with changes in tissue motility, positioning neutrophils farther from the skin entry vessels and closer to the skin surface. Neutrophil diapedesis was partially dependent on SLPI within the neutrophils themselves. The impact of SLPI on neutrophil movement was further supported by the increased migration of human neutrophils in the presence of neutrophil-penetrant recombinant SLPI. Additionally, our data suggest that neutrophils with varying capacities for vessel wall interaction are released from the bone marrow into circulation in an SLPI-dependent manner. These findings establish a role for SLPI in regulating the spatiotemporal infiltration of neutrophils into the skin in psoriasis, highlighting its relevance to psoriasis pathophysiology.

The use of a ketogenic diet (KD) in glioma is currently tested as an adjuvant treatment in standard chemotherapy regimens. The metabolic shift induced by the KD leads to the generation of ketone bodies that can influence glioma cells and the surrounding microenvironment, but the mechanisms have not yet been fully elucidated. Here, we investigated the potential involvement of glial cells as mediators of the KD-induced effects on tumor growth and survival rate in glioma-bearing mice. Specifically, we describe that exposing glioma-bearing mice to a KD or to β-hydroxybutyrate (β-HB), one of the main KD metabolic products, reduced glioma growth in vivo, induced a pro-inflammatory phenotype in astrocytes and increased functional glutamate transporters. Moreover, we described increased intracellular basal Ca²⁺ levels in GL261 glioma cells treated with β-HB or co-cultured with astrocytes. These data suggest that pro-inflammatory astrocytes triggered by β-HB can be beneficial in counteracting glioma proliferation and neuronal excitotoxicity, thus protecting brain parenchyma.

Charcot Marie Tooth (CMT) or hereditary motor and sensory neuropathy is a heterogeneous neurological disorder leading to nerve damage and muscle weakness. Although multiple mutations associated with CMT were identified, the cellular and molecular mechanisms of this pathology are still unclear, although most of the subtype of this disease involve mitochondrial dysfunction and oxidative stress in the mechanism of pathology. Using patients' fibroblasts of autosomal recessive, predominantly demyelinating form of CMT-CMT4B3 subtype, we studied the effect of these mutations on mitochondrial metabolism and redox balance. We have found that CMT4B3-associated mutations decrease mitochondrial membrane potential and mitochondrial NADH redox index suggesting an increase rate of mitochondrial respiration in these cells. However, mitochondrial dysfunction had no profound effect on the overall levels of ATP and on the energy capacity of these cells. Although the rate of reactive oxygen species production in mitochondria and cytosol in fibroblasts with CMT4B3 pathology was not significantly higher than in control, the level of GSH was significantly lower. Lower level of glutathione was most likely induced by the lower level of NADPH production, which was used for a GSH cycling, however, expression levels and activity of the major NADPH producing enzyme Glucose-6-Phosphate Dehydrogenase (G6PDH) was not altered. Low level of GSH renders the fibroblast with CMT4B3 pathology more sensitive to oxidative stress and further treatment of cells with hydroperoxide increases CMT patients' fibroblast death rates compared to control. Thus, CMT4B3 pathology makes cells vulnerable to oxidative stress due to the lack of major endogenous antioxidant GSH.