The present study aimed to investigate the effects of eccentric treadmill exercise on adaptive hypertrophy of skeletal muscle in rats. Thirty-two 3-month-old Sprague Dawley (SD) rats were selected and randomly assigned to one of the four groups based on their body weights: 2-week quiet control group (2C), 2-week downhill running exercise group (2E), 4-week quiet control group (4C), and 4-week downhill running exercise group (4E). The downhill running protocol for rats in the exercise groups involved slope of -16°, running speed of 16 m/min, training duration of 90 min, and 5 training sessions per week. Twenty-four hours after the final session of training, all the four groups of rats underwent an exhaustion treadmill exercise. After resting for 48 h, all the rats were euthanized and their gastrocnemius muscles were harvested for analysis. HE staining was used to measure the cross-sectional area (CSA) and diameter of muscle fibers. Transmission electron microscope was used to observe the ultrastructural changes in muscle fibers. Purithromycin surface labeling translation method was used to measure protein synthesis rate. Immunofluorescence double labeling was used to detect the colocalization levels of lysosomal-associated membrane protein 2 (Lamp2)-leucyl-tRNA synthetase (LARS) and Lamp2-mammalian target of rapamycin (mTOR). Western blot was used to measure the protein expression levels of myosin heavy chain (MHC) IIb and LARS, as well as the phosphorylation levels of mTOR, p70 ribosomal protein S6 kinase (p70S6K), and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1). The results showed that, compared with the 2C group rats, the 2E group rats showed significant increases in wet weight of gastrocnemius muscle, wet weight/body weight ratio, running distance, running time, pre- and post-exercise blood lactate levels, myofibrillar protein content, colocalization levels of Lamp2-LARS and Lamp2-mTOR, and LARS protein expression. Besides these above changes, compared with the 4C group, the 4E group further exhibited significantly increased fiber CSA, fiber diameter, protein synthesis rate, and phosphorylation levels of mTOR, p70S6K, and 4E-BP1. Compared with the quiet control groups, the exercise groups exhibited ultrastructural damage of rat gastrocnemius muscle, which was more pronounced in the 4E group. These findings suggest that eccentric treadmill exercise may promote mTOR translocation to lysosomal membrane, activating mTOR signaling via up-regulating LARS expression. This, in turn, increases protein synthesis rate through the mTOR-p70S6K-4E-BP1 signaling pathway, promoting protein deposition and inducing adaptive skeletal muscle hypertrophy. Although the ultrastructural changes of skeletal muscle are more pronounced, the relatively long training cycles during short-term exercise periods have a more significant effect on promoting gastrocnemius muscle protein synthesis and adaptive hypertrophy.
Animals ; Rats, Sprague-Dawley ; Physical Conditioning, Animal/physiology* ; Rats ; Muscle, Skeletal/metabolism* ; TOR Serine-Threonine Kinases/metabolism* ; Male ; Hypertrophy ; Adaptation, Physiological/physiology* ; Adaptor Proteins, Signal Transducing/metabolism* ; Ribosomal Protein S6 Kinases, 70-kDa/metabolism* ; Intracellular Signaling Peptides and Proteins

Hippo signaling is a highly conserved pathway central to diverse cellular processes. Dysregulation of this pathway not only leads to developmental abnormalities but is also closely related to the occurrence and progression of various cancers. Recent studies have uncovered that, in addition to the classical signaling cascade regulation, biomolecular condensates formed via phase separation play a key role in the spatiotemporal regulation of Hippo signaling. In this review, we provide a summary of the latest research progress on the regulation of the Hippo signaling pathway by phase separation, with a particular focus on transcriptional activation mediated by Yes-associated protein (YAP)/transcriptional coactivator with post-synaptic density-95, disks-large, and zonula occludens-1 (PDZ)-binding domain (TAZ) condensates. Furthermore, we discuss the utility of chemical crosslinking combined with mass spectrometry to analyze the TAZ condensate interactome and examine the role of the protein fused in sarcoma (FUS) in modulating the biophysical properties of TAZ condensates, which in turn influence their transcriptional activity and pro-tumorigenic functions. These insights not only advance our understanding of Hippo signaling but also offer new perspectives for therapeutic interventions targeting diseases linked to dysregulated YAP/TAZ activity.
Humans ; Signal Transduction ; Hippo Signaling Pathway ; Protein Serine-Threonine Kinases/physiology* ; Animals ; Biomolecular Condensates/metabolism* ; Transcription Factors/metabolism* ; YAP-Signaling Proteins ; Adaptor Proteins, Signal Transducing/metabolism* ; Neoplasms ; Transcriptional Activation ; Intracellular Signaling Peptides and Proteins/metabolism*

Approximately 20% to 30% of the global workforce is engaged in shift work. As a significant cause of circadian disruption, shift work is closely associated with an increased risk for periodontitis. Nevertheless, how shift work-related circadian disruption functions in periodontitis remains unknown. Herein, we employed a simulated shift work model constructed by controlling the environmental light-dark cycles and revealed that shift work-related circadian disruption exacerbated the progression of experimental periodontitis. RNA sequencing and in vitro experiments indicated that downregulation of the core circadian protein brain and muscle ARNT-like protein 1 (BMAL1) and activation of the Gasdermin D (GSDMD)-mediated pyroptosis were involved in the pathogenesis of that. Mechanically, BMAL1 regulated GSDMD-mediated pyroptosis by suppressing NOD-like receptor protein 3 (NLRP3) inflammasome signaling through modulating nuclear receptor subfamily 1 group D member 1 (NR1D1), and inhibiting Gsdmd transcription via directly binding to the E-box elements in its promoter. GSDMD-mediated pyroptosis accelerated periodontitis progression, whereas downregulated BMAL1 under circadian disruption further aggravated periodontal destruction by increasing GSDMD activity. And restoring the level of BMAL1 by circadian recovery and SR8278 injection alleviated simulated shift work-exacerbated periodontitis via lessening GSDMD-mediated pyroptosis. These findings provide new evidence and potential interventional targets for circadian disruption-accelerated periodontitis.
Pyroptosis/physiology* ; ARNTL Transcription Factors/metabolism* ; Animals ; Periodontitis/etiology* ; Mice ; Phosphate-Binding Proteins/metabolism* ; Shift Work Schedule/adverse effects* ; Intracellular Signaling Peptides and Proteins/metabolism* ; Mice, Inbred C57BL ; Male ; Disease Models, Animal ; Gasdermins

BACKGROUNDSleep/wake disturbances in patients with amyotrophic lateral sclerosis (ALS) are well-documented, however, no animal or mechanistic studies on these disturbances exist. Orexin is a crucial neurotransmitter in promoting wakefulness in sleep/wake regulation, and may play an important role in sleep disturbances in ALS. In this study, we used SOD1-G93A transgenic mice as an ALS mouse model to investigate the sleep/wake disturbances and their possible mechanisms in ALS.

METHODSElectroencephalogram/electromyogram recordings were performed in SOD1-G93A transgenic mice and their littermate control mice at the ages of 90 and 120 days, and the samples obtained from these groups were subjected to quantitative reverse transcriptase-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay.

RESULTSFor the first time in SOD1-G93A transgenic mice, we observed significantly increased wakefulness, reduced sleep time, and up-regulated orexins (prepro-orexin, orexin A and B) at both 90 and 120 days. Correlation analysis confirmed moderate to high correlations between sleep/wake time (total sleep time, wakefulness time, rapid eye movement [REM] sleep time, non-REM sleep time, and deep sleep time) and increase in orexins (prepro-orexin, orexin A and B).

CONCLUSIONSleep/wake disturbances occur before disease onset in this ALS mouse model. Increased orexins may promote wakefulness and result in these disturbances before and after disease onset, thus making them potential therapeutic targets for amelioration of sleep disturbances in ALS. Further studies are required to elucidate the underlying mechanisms in the future.

Amyotrophic Lateral Sclerosis ; genetics ; metabolism ; Animals ; Female ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Male ; Mice ; Mice, Transgenic ; Neuropeptides ; genetics ; metabolism ; Orexins ; Reverse Transcriptase Polymerase Chain Reaction ; Sleep ; physiology ; Superoxide Dismutase ; genetics ; metabolism ; Superoxide Dismutase-1 ; Wakefulness ; physiology

Animals ; Cadherins ; metabolism ; Cell Cycle Proteins ; genetics ; metabolism ; Cell Differentiation ; Cell Line, Tumor ; Early Growth Response Protein 1 ; genetics ; metabolism ; Estradiol ; physiology ; Eukaryotic Initiation Factor-3 ; metabolism ; Genes, Tumor Suppressor ; physiology ; HSP90 Heat-Shock Proteins ; metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Iron ; metabolism ; Neoplasms ; metabolism ; pathology

Smac is a mitochondrial protein that interacts with inhibitor of apoptosis proteins (IAPs). Upon apoptotic stimuli, the Smac is released into the cytoplasm to inhibit the capase-binding activity of IAPs. The low expression of Smac in tissues has been reported existing in various cancers. Smac plays key roles in prognosis and chemoradiotherapy resistance of malignant tumor besides neoplasm genesis and growth. Furthermore, Smac may be a molecular therapeutic target in cancer patients. Overexpression of Smac by transfecting extrinsic Smac gene or Smac mimetic into tumor cell can improve their sensitivity to radiotherapy and chemotherapy, which has great significance to the treatment of tumor. Our review will focus on the roles of Smac in structure, pro-apoptotic mechanism, tissue distribution and cancer treatment.
Humans ; Intracellular Signaling Peptides and Proteins ; chemistry ; metabolism ; physiology ; Mitochondrial Proteins ; chemistry ; metabolism ; physiology ; Neoplasms ; therapy ; Tissue Distribution

This study investigated the changes in human umbilical vein endothelial cells (HUVECs) induced by overexpression of endothelial nitric oxide synthase traffic inducer (NOSTRIN) and its role in cellular injury. Recombinant NOSTRIN-expressing and empty vectors were transfected into cultured HUVECs, and factor VIII-related antigen was examined by using immunohistochemical analysis. Growth curves were generated for both transfected and untransfected cells and these indicated that the proliferative ability of cells overexpressing NOSTRIN was significantly decreased. The expression of NOSTRIN and eNOS proteins was detected by using Western blot analysis, endothelial NOS (eNOS) activity was assayed by using spectrophotometry, and NO2 (-)/NO3 (-) levels were measured using nitrate reductase. Immunohistochemical analysis demonstrated that all groups expressed NOSTRIN in the plasma membrane and cytoplasm, and Western blot analysis confirmed that NOSTRIN levels were significantly higher in cells transfected with the NOSTRIN plasmid (P<0.01). The activity of eNOS and the levels of NO2 (-)/NO3 (-) were significantly decreased in NOSTRIN overexpressing cells as compared with empty vector and untransfected cells (P<0.01 and P<0.01, respectively). Morphological and ultrastructural changes were observed under light and electron microscopy, and it was found that NOSTRIN-overexpressing cells were elongated with deformities of the karyotheca, injury to the plasma membrane, increased lipids in the cytoplasm, and shortened microvilli. This study showed that overexpression of NOSTRIN had a significant effect on eNOS activity in HUVECs and resulted in significant cellular damage.
Apoptosis ; physiology ; Cell Line ; Cell Proliferation ; Cell Survival ; physiology ; Endothelial Cells ; pathology ; physiology ; Humans ; Intracellular Signaling Peptides and Proteins ; metabolism ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase Type III ; metabolism ; Umbilical Veins ; metabolism ; pathology ; Up-Regulation

OBJECTIVETo establish the method for cotransferring human A20 gene and human heme oxygenase-1 (HO-1) gene into the isolated rat islets using lentiviral transfection system, and to study the protective effect of A20 and HO-1 protein against the apoptosis induced by cycloheximide (CHX) and TNF-α, and finally to explore the underlying mechanism.

METHODThe A20 gene and HO-1 gene were cloned and inserted into the lentiviral transfection system. The efficacy of gene transfer was measured by the intensity of the enhanced green fluorescent protein (EGFP) fluorescence-positive islets. Western blot was applied to verify the expression of the A20 and HO-1 genes. To induce apoptosis in vitro, the isolated islets were treated with CHX+TNF-α, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and the fluorescence-activated cell sorting (FACS) methods were used to evaluate the apoptosis of the islet cells and Western blot was used to detect caspase-3 activation.

RESULT(1) A20 and HO-1 genes were introduced into the isolated islets by lentiviral transfection, both of the genes were highly expressed in the islets after 96 hours culture detected by Western blot method. (2) The insulin levels in the cell culture medium from A20 and/or HO-1 transgenic islets were significantly higher than that in non-transgenic controls (P < 0.01). (3)After CHX + TNF-alpha treatment, the cell culture medium insulin concentration in the A20 gene transfected group [(93.58 ± 4.12)µg/ml], HO-1 gene transfected group [(88.98 ± 4.77) µg/ml ] and A20/HO-1 co-transfected group [(103.33 ± 3.16) µg/ml] were significantly higher than that in the EGFP group [(9.03 ± 0.65) µg/ml ] and the control group [(8.86 ± 0.38) µg/ml] (P < 0.001). Minimum expression level of the activated caspase-3 was found in the A20/HO-1 co-transfected group.

CONCLUSIONThe lentiviral gene transfer system was an efficient and stable gene transfer vector, the over-expressed A20 and HO-1 protein delivered via lentivirus could preserve rats' islets function and act against the apoptosis induced by CHX and TNF-α.

Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cell Line ; DNA-Binding Proteins ; genetics ; metabolism ; Female ; Flow Cytometry ; Genetic Vectors ; Heme Oxygenase-1 ; genetics ; metabolism ; Humans ; Insulin ; metabolism ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Islets of Langerhans ; drug effects ; enzymology ; physiology ; Lentivirus ; genetics ; Male ; Nuclear Proteins ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Transfection ; methods ; Tumor Necrosis Factor alpha-Induced Protein 3 ; Tumor Necrosis Factor-alpha ; pharmacology

Hippo signaling plays a crucial role in growth control and tumor suppression by regulating cell proliferation, apoptosis, and differentiation. How Hippo signaling is regulated has been under extensive investigation. Over the past three years, an increasing amount of data have supported a model of actin cytoskeleton blocking Hippo signaling activity to allow nuclear accumulation of a downstream effector, Yki/Yap/Taz. On the other hand, Hippo signaling negatively regulates actin cytoskeleton organization. This review provides insight on the mutual regulatory mechanisms between Hippo signaling and actin cytoskeleton for a tight control of cell behaviors during animal development, and points out outstanding questions for further investigations.
Actin Cytoskeleton ; physiology ; Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Animals ; Cell Proliferation ; Drosophila Proteins ; genetics ; metabolism ; Gene Expression Regulation ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Nuclear Proteins ; genetics ; metabolism ; Phosphoproteins ; genetics ; metabolism ; Phosphorylation ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Signal Transduction ; Trans-Activators ; genetics ; metabolism ; Transcription Factors ; genetics ; metabolism

Mutations in LR RK2 (Leucine rich repeat kinase 2) are a major cause of Parkinson's disease (PD). We and others reported recently that expression of the pathogenic gainof-function mutant form of LRRK2, LRRK2 G2019S, induces mitochondrial fission in neurons through DLP1. Here we provide evidence that expression of LRRK2 G2019S stimulates mitochondria loss or mitophagy. We have characterized several LRRK2 interacting proteins and found that LRRK2 interacts with ULK1 which plays an essential role in autophagy. Knockdown of either ULK1 or DLP1 expression with shRNAs suppresses LRRK2 G2019S expression-induced mitochondrial clearance, suggesting that LRRK2 G2019S expression induces mitochondrial fission through DLP1 followed by mitophagy via an ULK1 dependent pathway. In addition to ULK1, we found that LRRK2 interacts with the endogenous MKK4/7, JIP3 and coordinates with them in the activation of JNK signaling. Interestingly, LRRK2 G2019S-induced loss of mitochondria can also be suppressed by 3 different JNK inhibitors, implying the involvement of the JNK pathway in the pathogenic mechanism of mutated LRRK2. Thus our findings may provide an insight into the complicated pathogenesis of PD as well as some clues to the development of novel therapeutic strategies.
Amino Acid Substitution ; Autophagosomes ; metabolism ; pathology ; Autophagy-Related Protein-1 Homolog ; chemistry ; genetics ; metabolism ; GTP Phosphohydrolases ; antagonists & inhibitors ; genetics ; metabolism ; Gene Knockdown Techniques ; HeLa Cells ; Humans ; Intracellular Signaling Peptides and Proteins ; chemistry ; genetics ; metabolism ; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 ; chemistry ; genetics ; metabolism ; MAP Kinase Signaling System ; Microtubule-Associated Proteins ; antagonists & inhibitors ; genetics ; metabolism ; Mitochondrial Degradation ; genetics ; physiology ; Mitochondrial Proteins ; antagonists & inhibitors ; genetics ; metabolism ; Mutant Proteins ; chemistry ; genetics ; metabolism ; Mutation ; Parkinson Disease ; genetics ; metabolism ; pathology ; Protein Interaction Domains and Motifs ; Recombinant Proteins ; chemistry ; genetics ; metabolism