Skeletal muscle cystathionine γ-lyase deficiency promotes obesity and insulin resistance and results in hyperglycemia and skeletal muscle injury upon HFD in mice.

OBJECTIVES: The objective of this study was to investigate whether skeletal muscle cystathionine γ-lyase (CTH) contributes to high-fat diet (HFD)-induced metabolic disorders using skeletal muscle Cth knockout (CthΔskm) mice. METHODS: The CthΔskm mice and littermate Cth-floxed (Cthf/f) mice were fed with either HFD or chow diet for 13 weeks. Metabolomics and transcriptome analysis were used to assess the impact of CTH deficiency in skeletal muscle. RESULTS: Metabolomics coupled with transcriptome showed that CthΔskm mice displayed impaired energy metabolism and some signaling pathways linked to insulin resistance (IR) in skeletal muscle although the mice had normal insulin sensitivity. HFD led to reduced CTH expression and impaired energy metabolism in skeletal muscle in Cthf/f mice. CTH deficiency and HFD had some common pathways enriched in the aspects of amino acid metabolism, carbon metabolism, and fatty acid metabolism. CthΔskm+HFD mice exhibited increased body weight gain, fasting blood glucose, plasma insulin, and IR, and reduced glucose transporter 4 and CD36 expression in skeletal muscle compared to Cthf/f+HFD mice. Impaired mitochondria and irregular arrangement in myofilament occurred in CthΔskm+HFD mice. Omics analysis showed differential pathways enriched between CthΔskm mice and Cthf/f mice upon HFD. More severity in impaired energy metabolism, reduced AMPK signaling, and increased oxidative stress and ferroptosis occurred in CthΔskm+HFD mice compared to Cthf/f+HFD mice. DISCUSSION: Our results indicate that skeletal muscle CTH expression dysregulation contributes to metabolism disorders upon HFD.

Single-cell RNA sequencing and ATAC sequencing identify novel biomarkers for bicuspid aortic valve-associated thoracic aortic aneurysm.

Introduction: Bicuspid aortic valve (BAV) is the most prevalent congenital cardiovascular defect and known to cause thoracic aortic aneurysms (TAAs). To improve our understanding of BAV pathogenesis, we characterized the cellular composition of BAV tissues and identified molecular changes in each cell population. Methods: Tissue samples from two patients with BAV and two heart transplant donors were analyzed using single-cell RNA sequencing, assay for transposase-accessible chromatin using sequencing, and weighted gene coexpression network analysis for differential gene analysis. TAA-related changes were evaluated by comparing the proportion of each cell type and gene expression profiles between TAA and control tissues. Further, by combining our single-cell RNA sequencing data with publicly available data from genome-wide association studies, we determined critical genes for BAV. Results: We found 20 cell subpopulations in TAA tissues, including multiple subtypes of smooth muscle cells, fibroblasts, macrophages, and T lymphocytes. This result suggested that these cells play multiple functional roles in BAV development. Several differentially expressed genes, including CD9, FHL1y, HSP90AA1, GAS6, PALLD, and ACTA2, were identified. Discussion: We believe that this comprehensive assessment of the cellular composition of TAA tissues and the insights into altered gene expression patterns can facilitate identification of novel diagnostic biomarkers and therapeutic targets for BAV-associated TAA.

LPD-3 as a megaprotein brake for aging and insulin-mTOR signaling in C. elegans.

Insulin-mechanistic target of rapamycin (mTOR) signaling drives anabolic growth during organismal development; its late-life dysregulation contributes to aging and limits lifespans. Age-related regulatory mechanisms and functional consequences of insulin-mTOR remain incompletely understood. Here, we identify LPD-3 as a megaprotein that orchestrates the tempo of insulin-mTOR signaling during C. elegans aging. We find that an agonist insulin, INS-7, is drastically overproduced from early life and shortens lifespan in lpd-3 mutants. LPD-3 forms a bridge-like tunnel megaprotein to facilitate non-vesicular cellular lipid trafficking. Lipidomic profiling reveals increased hexaceramide species in lpd-3 mutants, accompanied by up-regulation of hexaceramide biosynthetic enzymes, including HYL-1. Reducing the abundance of HYL-1, insulin receptor/DAF-2 or mTOR/LET-363, normalizes INS-7 levels and rescues the lifespan of lpd-3 mutants. LPD-3 antagonizes SINH-1, a key mTORC2 component, and decreases expression with age. We propose that LPD-3 acts as a megaprotein brake for organismal aging and that its age-dependent decline restricts lifespan through the sphingolipid-hexaceramide and insulin-mTOR pathways.

Investigation of a UPR-Related Gene Signature Identifies the Pro-Fibrotic Effects of Thrombospondin-1 by Activating CD47/ROS/Endoplasmic Reticulum Stress Pathway in Lung Fibroblasts.

Unfolded protein response (UPR) signaling and endoplasmic reticulum (ER) stress have been linked to pulmonary fibrosis. However, the relationship between UPR status and pulmonary function and prognosis in idiopathic pulmonary fibrosis (IPF) patients remains largely unknown. Through a series of bioinformatics analyses, we established a correlation between UPR status and pulmonary function in IPF patients. Furthermore, thrombospondin-1 (TSP-1) was identified as a potential biomarker for prognostic evaluation in IPF patients. By utilizing both bulk RNA profiling and single-cell RNA sequencing data, we demonstrated the upregulation of TSP-1 in lung fibroblasts during pulmonary fibrosis. Gene set enrichment analysis (GSEA) results indicated a positive association between TSP-1 expression and gene sets related to the reactive oxygen species (ROS) pathway in lung fibroblasts. TSP-1 overexpression alone induced mild ER stress and pulmonary fibrosis, and it even exacerbated bleomycin-induced ER stress and pulmonary fibrosis. Mechanistically, TSP-1 promoted ER stress and fibroblast activation through CD47-dependent ROS production. Treatment with either TSP-1 inhibitor or CD47 inhibitor significantly attenuated BLM-induced ER stress and pulmonary fibrosis. Collectively, these findings suggest that the elevation of TSP-1 during pulmonary fibrosis is not merely a biomarker but likely plays a pathogenic role in the fibrotic changes in the lung.

Attenuation of Sepsis-Induced Acute Kidney Injury by Exogenous H2S via Inhibition of Ferroptosis.

Sepsis-associated acute kidney injury (SA-AKI) results in significant morbidity and mortality, and ferroptosis may play a role in its pathogenesis. Our aim was to examine the effect of exogenous H2S (GYY4137) on ferroptosis and AKI in in vivo and in vitro models of sepsis and explore the possible mechanism involved. Sepsis was induced by cecal ligation and puncture (CLP) in male C57BL/6 mice, which were randomly divided into the sham, CLP, and CLP + GYY4137 group. The indicators of SA-AKI were most prominent at 24 h after CLP, and analysis of the protein expression of ferroptosis indicators showed that ferroptosis was also exacerbated at 24 h after CLP. Moreover, the level of the endogenous H2S synthase CSE (Cystathionine-γ-lyase) and endogenous H2S significantly decreased after CLP. Treatment with GYY4137 reversed or attenuated all these changes. In the in vitro experiments, LPS was used to simulate SA-AKI in mouse renal glomerular endothelial cells (MRGECs). Measurement of ferroptosis-related markers and products of mitochondrial oxidative stress showed that GYY4137 could attenuate ferroptosis and regulate mitochondrial oxidative stress. These findings imply that GYY4137 alleviates SA-AKI by inhibiting ferroptosis triggered by excessive mitochondrial oxidative stress. Thus, GYY4137 may be an effective drug for the clinical treatment of SA-AKI.

LPD-3 as a megaprotein brake for aging and insulin-mTOR signaling in C. elegans.

Insulin-mTOR signaling drives anabolic growth during organismal development, while its late-life dysregulation may detrimentally contribute to aging and limit lifespans. Age-related regulatory mechanisms and functional consequences of insulin-mTOR remain incompletely understood. Here we identify LPD-3 as a megaprotein that orchestrates the tempo of insulin-mTOR signaling during C. elegans aging. We find that an agonist insulin INS-7 is drastically over-produced in early life and shortens lifespan in lpd-3 mutants, a C. elegans model of human Alkuraya-Kucinskas syndrome. LPD-3 forms a bridge-like tunnel megaprotein to facilitate phospholipid trafficking to plasma membranes. Lipidomic profiling reveals increased abundance of hexaceramide species in lpd-3 mutants, accompanied by up-regulation of hexaceramide biosynthetic enzymes, including HYL-1 (Homolog of Yeast Longevity). Reducing HYL-1 activity decreases INS-7 levels and rescues the lifespan of lpd-3 mutants through insulin receptor/DAF-2 and mTOR/LET-363. LPD3 antagonizes SINH-1, a key mTORC2 component, and decreases expression with age in wild type animals. We propose that LPD-3 acts as a megaprotein brake for aging and its age-dependent decline restricts lifespan through the sphingolipid-hexaceramide and insulin-mTOR pathways.

Reduced hydrogen sulfide production contributes to adrenal insufficiency induced by hypoxia via modulation of NLRP3 inflammasome activation.

Objective: Adrenocortical responsiveness is critical for maintaining glucocorticoids production and homeostasis during stress. We sought to investigate adrenocortical responsiveness during hypoxia in mice and the mechanisms responsible for the regulation of adrenal responsiveness.Methods: (1) Adult male WT mice were randomly divided into four groups: normoxia, hypoxia (24h), hypoxia (72h), hypoxia (72h) + GYY4137(hydrogen sulfide (H2S) donor, 133mmol/kg/day); (2) WT mice were randomly divided into four groups: sham, adrenalectomy (ADX), sham+hypoxia, ADX+hypoxia; (3) Cse-/- mice were randomly divided into two groups: Cse-/-, Cse-/- +GYY4137.Results: The circulatory level of corticosteroid induced by ACTH stimulation was significantly reduced in the mice with hypoxia compared with control mice. The mortality rate induced by lipopolysaccharide (LPS) increased during hypoxia. Cystathionine-γ-lyase (CSE) expression was significantly reduced in adrenal glands during hypoxia. GYY4137 treatment significantly increased adrenal responsiveness and attenuated NLRP3 inflammasome activation in mice treated by hypoxia and Cse-/- mice. Furthermore, The sulfhydrated level of PSMA7 in adrenal gland was decreased in the mice with hypoxia and Cse-/- mice. PSMA7 was S-sulfhydrated at cysteine 70. Blockage of S-sulfhydration of PSMA7 increased NLRP3 expression in adrenocortical cells.Conclusion: Reduced H2S production mediated hypo-adrenocortical responsiveness and NLRP3 inflammasome activation via PAMA7 S-sulfhydration during hypoxia.

GPCR signaling regulates severe stress-induced organismic death in Caenorhabditis elegans.

How an organism dies is a fundamental yet poorly understood question in biology. An organism can die of many causes, including stress-induced phenoptosis, also defined as organismic death that is regulated by its genome-encoded programs. The mechanism of stress-induced phenoptosis is still largely unknown. Here, we show that transient but severe freezing-thaw stress (FTS) in Caenorhabditis elegans induces rapid and robust phenoptosis that is regulated by G-protein coupled receptor (GPCR) signaling. RNAi screens identify the GPCR-encoding fshr-1 in mediating transcriptional responses to FTS. FSHR-1 increases ligand interaction upon FTS and activates a cyclic AMP-PKA cascade leading to a genetic program to promote organismic death under severe stress. FSHR-1/GPCR signaling up-regulates the bZIP-type transcription factor ZIP-10, linking FTS to expression of genes involved in lipid remodeling, proteostasis, and aging. A mathematical model suggests how genes may promote organismic death under severe stress conditions, potentially benefiting growth of the clonal population with individuals less stressed and more reproductively privileged. Our studies reveal the roles of FSHR-1/GPCR-mediated signaling in stress-induced gene expression and phenoptosis in C. elegans, providing empirical new insights into mechanisms of stress-induced phenoptosis with evolutionary implications.

A conserved megaprotein-based molecular bridge critical for lipid trafficking and cold resilience.

Cells adapt to cold by increasing levels of unsaturated phospholipids and membrane fluidity through conserved homeostatic mechanisms. Here we report an exceptionally large and evolutionarily conserved protein LPD-3 in C. elegans that mediates lipid trafficking to confer cold resilience. We identify lpd-3 mutants in a mutagenesis screen for genetic suppressors of the lipid desaturase FAT-7. LPD-3 bridges the endoplasmic reticulum (ER) and plasma membranes (PM), forming a structurally predicted hydrophobic tunnel for lipid trafficking. lpd-3 mutants exhibit abnormal phospholipid distribution, diminished FAT-7 abundance, organismic vulnerability to cold, and are rescued by Lecithin comprising unsaturated phospholipids. Deficient lpd-3 homologues in Zebrafish and mammalian cells cause defects similar to those observed in C. elegans. As mutations in BLTP1, the human orthologue of lpd-3, cause Alkuraya-Kucinskas syndrome, LPD-3 family proteins may serve as evolutionarily conserved highway bridges critical for ER-associated non-vesicular lipid trafficking and resilience to cold stress in eukaryotic cells.

Resveratrol alleviates acute lung injury through regulating PLSCR-3-mediated mitochondrial dysfunction and mitophagy in a cecal ligation and puncture model.

Sepsis is considered as a life-threatening organ dysfunction caused by a dysregulated response of the host to an infection. Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a life-threatening condition, and is the type of organ injury that is most commonly induced by sepsis. Resveratrol (RSV) has been shown to exert a wide range of therapeutic effects due to its anti-inflammatory and anti-oxidant properties. The present study aimed to investigate whether RSV could mitigate sepsis-induced ALI/ARDS, and also to unravel the underlying mechanism. The model of sepsis was established by applying the cecal ligation and puncture (CLP) method, and mitochondria from the lung tissue were isolated to assess mitochondrial function, as determined from measuring mitochondrial superoxide production using MitoSOX red mitochondrial superoxide indicator and the membrane potential. It was found that RSV could exert a protective role in CLP-induced ALI/ARDS, as evidenced by moderate levels of inflammatory cell infiltration and interstitial edema, as well as decreased levels of C-reactive protein (P<0.01), interleukin (IL)-6 (P<0.01), IL-1ß (P<0.01) and tumor necrosis factor-α (P<0.01). Moreover, phospholipid scramblase 3 (PLSCR-3)-mediated mitochondrial dysfunction and mitophagy were shown to contribute towards the CLP-caused lung damage, which was reversed upon RSV administration, as demonstrated by improved mitochondrial function and markedly reduced increases in the protein levels of autophagy related (ATG)5 (P<0.01), ATG7 (P<0.05) and microtubule-associated protein 1A/1B-light chain 3 (LC3-Ⅰ/Ⅱ) (P<0.01), and a significantly increased expression of P62 (P<0.05). In addition, with regard to the CLP-induced lung injury in the mouse model, overexpression of PLSCR-3 was found to remove the beneficial effects observed upon RSV treatment. Taken together, the results of the present study have uncovered a novel molecular mechanism through which RSV may alleviate ALI/ARDS via regulating PLSCR-3-mediated mitochondrial dysfunction and mitophagy in CLP-induced mouse model.

The C. elegans homolog of human panic-disorder risk gene TMEM132D orchestrates neuronal morphogenesis through the WAVE-regulatory complex.

TMEM132D is a human gene identified with multiple risk alleles for panic disorders, anxiety and major depressive disorders. Defining a conserved family of transmembrane proteins, TMEM132D and its homologs are still of unknown molecular functions. By generating loss-of-function mutants of the sole TMEM132 ortholog in C. elegans, we identify abnormal morphologic phenotypes in the dopaminergic PDE neurons. Using a yeast two-hybrid screen, we find that NAP1 directly interacts with the cytoplasmic domain of human TMEM132D, and mutations in C. elegans tmem-132 that disrupt interaction with NAP1 cause similar morphologic defects in the PDE neurons. NAP1 is a component of the WAVE regulatory complex (WRC) that controls F-actin cytoskeletal dynamics. Decreasing activity of WRC rescues the PDE defects in tmem-132 mutants, whereas gain-of-function of TMEM132D in mammalian cells inhibits WRC, leading to decreased abundance of select WRC components, impaired actin nucleation and cell motility. We propose that metazoan TMEM132 family proteins play evolutionarily conserved roles in regulating NAP1 protein homologs to restrict inappropriate WRC activity, cytoskeletal and morphologic changes in the cell.

Hydrogen Sulfide Is a Regulator of Hemoglobin Oxygen-Carrying Capacity via Controlling 2,3-BPG Production in Erythrocytes.

Hydrogen sulfide (H2S) is naturally synthesized in a wide range of mammalian tissues. Whether H2S is involved in the regulation of erythrocyte functions remains unknown. Using mice with a genetic deficiency in a H2S natural synthesis enzyme cystathionine-γ-lyase (CSE) and high-throughput metabolomic profiling, we found that levels of erythrocyte 2,3-bisphosphoglycerate (2,3-BPG), an erythroid-specific metabolite negatively regulating hemoglobin- (Hb-) oxygen (O2) binding affinity, were increased in CSE knockout (Cse -/-) mice under normoxia. Consistently, the 50% oxygen saturation (P50) value was increased in erythrocytes of Cse -/- mice. These effects were reversed by treatment with H2S donor GYY4137. In the models of cultured mouse and human erythrocytes, we found that H2S directly acts on erythrocytes to decrease 2,3-BPG production, thereby enhancing Hb-O2 binding affinity. Mouse genetic studies showed that H2S produced by peripheral tissues has a tonic inhibitory effect on 2,3-BPG production and consequently maintains Hb-O2 binding affinity in erythrocytes. We further revealed that H2S promotes Hb release from the membrane to the cytosol and consequently enhances bisphosphoglycerate mutase (BPGM) anchoring to the membrane. These processes might be associated with S-sulfhydration of Hb. Moreover, hypoxia decreased the circulatory H2S level and increased the erythrocyte 2,3-BPG content in mice, which could be reversed by GYY4137 treatment. Altogether, our study revealed a novel signaling pathway that regulates oxygen-carrying capacity in erythrocytes and highlights a previously unrecognized role of H2S in erythrocyte 2,3-BPG production.

NLRP3 inflammasome-dependent pyroptosis and apoptosis in hippocampus neurons mediates depressive-like behavior in diabetic mice.

A relatively large number of diabetic patients risk complications of clinical depression that lead to poorer quality of life, however the precise mechanisms for diabetes-associated depression are not fully understood. Links between hyperglycemia-induced oxidative stress and NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation have been reported in the pathogenesis of diabetes. The present study aimed to elucidate the contribution of NLRP3-mediated apoptotic/pyroptotic neuronal cell death to diabetes-associated depression. We found that depressive-like behavior in streptozotocin (STZ)-induced diabetic mice was associated with hippocampal NLRP3 inflammasome activation. Hyperglycemia increased reactive oxygen species (ROS) production, thus leading to NLRP3 inflammasome activation in hippocampal neurons. It was found that STZ treatment induced apoptotic and pyroptotic cell death in the hippocampus as evidenced by increases of cleaved caspase 3 positive hippocampal neurons, TUNEL-positive cells, protein levels of p53, Bax, Puma, and the cleaved GSDMD N-terminal fragment, all of which were decreased in NLRP3 deficient mice. Using murine hippocampal neuronal cell line HT22, we found that high glucose induced apoptotic and pyroptotic cell death in a NLRP3 inflammasome-dependent manner in vitro. In addition, NLRP3 deficiency alleviated depressive-like behavior in STZ-induced diabetic mice. Our results suggest that hyperglycemia results in apoptosis and pyroptosis of hippocampal neuron cells in a NLRP3-dependent manner, which was associated with the depressive phenotypes evoked by STZ-induced diabetes. The study identifies a novel function of NLRP3 activation in high glucose-induced neuronal cell death, which sheds further light on the pathogenesis and new therapeutic targets of diabetes-associated depression.

[Construction of transgenic mice with specific Cre recombinase expression in the zona fasciculata in adrenal cortex].

The adrenal gland is an important endocrine organ of human body. CYP11B1 gene was specifically expressed in the zona fasciculata in adrenal cortex. In order to better study the function of genes specifically expressed in the zona fasciculata in adrenal cortex, the mice with Cre recombinase specifically expressed in the zona fasciculata in adrenal cortex were constructed. It was then confirmed that CYP11B1 was specifically expressed in adrenal glands. Then, using CRISPR/Cas9 technique, CYP11B1-2A-GfpCre recombinant vector was constructed and subsequently injected into the fertilized eggs of mice. It was confirmed that the Cre gene was mainly expressed in the zona fasciculata in adrenal cortex of CYP11B1Cre mice by using mTmG and LacZ staining. The CYP11B1Cre mice were then mated with cystathionine γ-lyase (CTH)f/f mice, thereby generating CTHf/f/CYP11B1Cre mice. It was also confirmed that CTH gene in the zona fasciculata in adrenal cortex was specifically knocked out in these mice. These results suggest that transgenic mice with specific Cre recombinase expression in the zona fasciculata in adrenal cortex were constructed successfully. This animal model can be a powerful tool for the study of the function of genes expressed in the zona fasciculata in adrenal cortex.

Endogenous H2S resists mitochondria-mediated apoptosis in the adrenal glands via ATP5A1 S-sulfhydration in male mice.

In a previous study, we showed that endogenous hydrogen sulfide (H2S) plays a key role in the maintenance of intact adrenal cortex function via the protection of mitochondrial function during endoxemia. We further investigated whether mitochondria-mediated apoptosis is involved in H2S protection of adrenal function. LPS treatment resulted in mitochondria-mediated apoptosis in the adrenal glands of male mice, and these effects were prevented by the H2S donor GYY4137. In the model of Y1 cells, the LPS-induced mitochondria-mediated apoptosis and blunt response to ACTH were rescued by GYY4137. The H2S-generating enzyme cystathionine-ß-synthase (CBS) knockout heterozygous (CBS+/-) mice showed mitochondria-mediated apoptosis in the adrenal gland and adrenal insufficiency. GYY4137 treatment restored adrenal function and eliminated mitochondria-mediated apoptosis. Maleimide assay combined with mass spectrometry analysis showed that a number of proteins in mitochondria were S-sulfhydrated in the adrenal gland. ATP5A1 was further confirmed as S-sulfhydrated using a modified biotin switch assay. The level of S-sulfhydrated ATP5A1 was decreased in the adrenal gland of endotoxemic and CBS+/- mice, which was restored by GYY4137. ATP5A1 was identified as sulfhydrated at cysteine 244 by H2S. Overexpression of the cysteine 244 mutant ATP5A1 in Y1 cells resulted in a loss of LPS-induced mitochondria-mediated apoptosis and GYY4137 restoration of LPS-induced hyporesponsiveness to ACTH. Collectively, the present study revealed that decreased H2S generation leads to mitochondrial-mediated apoptosis in the adrenal cortex and a blunt response to ACTH. S-sulfhydration of ATP5A1 at cysteine 244 is an important molecular mechanism by which H2S maintains mitochondrial function and steroidogenesis in the adrenal glands.

Protective effects of resveratrol on mitochondrial function in the hippocampus improves inflammation-induced depressive-like behavior.

Growing evidence suggests that inflammatory processes may be involved in depressive disorders. Inflammation is known to induce mitochondrial dysfunction in the nervous system. However, whether mitochondrial dysfunction is involved in the occurrence of inflammation-induced depressive-like behavior remains to be investigated. The present study aims to firstly, clarify whether mitochondrial dysfunction contributes to lipopolysaccharide (LPS)-induced depression-like behavior in mice and secondly, determine whether the anti-oxidant resveratrol alleviates inflammation-induced depressive-like behavior through the prevention of mitochondrial dysfunction in the hippocampus. We found that the administration of LPS led to mitochondrial oxidative stress and dysfunction as evidenced by increased mitochondrial superoxide production and decreased mitochondrial membrane potential and ATP production in the hippocampus. These effects were attenuated by intracerebroventricular (ICV) Injection of the mitochondria-targeted antioxidant Mito-TEMPO. LPS-treated mice displayed depressive-like behaviors as evidenced by reduced sucrose preference, increased immobility time and decreased struggling time in the forced swimming test. Both Mito-TEMPO and resveratrol could significantly improve the LPS-induced depressive-like behaviors. In contrast, ICV Injection of rotenone, the mitochondrial respiratory chain inhibitor, induced mitochondrial oxidative stress and dysfunction in the hippocampus, and resulted in depressive-like behaviors. Moreover, resveratrol alleviated the LPS-induced apoptosis of hippocampal cells. The antidepressant action of resveratrol was accomplished through the interruption of mitochondrial oxidative stress and the prevention of cell apoptosis in the hippocampus. These findings support the potential for resveratrol as a possible pharmacological agent for depression treatment in the future.

Protein tyrosine phosphatase SHP-1 modulates osteoblast differentiation through direct association with and dephosphorylation of GSK3ß.

SHP-1, the Src homology-2 (SH2) domain-containing phosphatase 1, is a cytosolic protein-tyrosine phosphatase (PTP) predominantly expressed in hematopoietic-derived cells. Previous studies have focused on the involvement of SHP-1 in osteoclastogenesis. Using primary cultured mouse fetal calvaria-derived osteoblasts as a model, this study aims to investigate the effects of SHP-1 on differentiation and mineralization of osteoblasts and elucidate the signaling pathways responsible for these effects. We found that osteoblasts treated by osteogenic media showed significant increase in SHP-1 expression, which contributed to osteoblastic differentiation and mineralization. Using immunoprecipitation assay, we found that a direct association between SHP-1 and glycogen synthase kinase (GSK)-3ß could be detected in differentiated osteoblasts and was significantly inhibited by SHP-1 inhibitor NSC87877. Inhibition of SHP-1 activated GSK3ß, thereby leading to suppression of osteoblast differentiation and mineralization, which could be rescued by the inhibitor of GSK3ß. In addition, we found that rosiglitazone (RSG) treatment led to significant decrease in SHP-1 expression. Overexpression of SHP-1 reversed RSG-induced GSK3ß activation, thus rescuing the inhibitory effect of RSG on osteoblast differentiation and mineralization. These findings suggest that protein tyrosine phosphatase SHP-1 may act as a positive regulator of osteoblast differentiation through direct association with and dephosphorylation of GSK3ß. Downregulation of SHP-1 may contribute to RSG-induced inhibition of mouse calvaria osteoblast differentiation by activating GSK3ß-dependent pathway.

H2S Attenuates LPS-Induced Acute Lung Injury by Reducing Oxidative/Nitrative Stress and Inflammation.

BACKGROUND: Hydrogen sulfide (H2S), known as the third endogenous gaseous transmitter, has received increasing attention because of its diverse effects, including angiogenesis, vascular relaxation and myocardial protection.We aimed to investigate the role of H2S in oxidative/nitrative stress and inflammation in acute lung injury (ALI) induced by endotoxemia. METHODS: Male ICR mice were divided in six groups: (1) Control group; (2) GYY4137treatment group; (3) L-NAME treatment group; (4) lipopolysaccharide (LPS) treatment group; (5) LPS with GYY4137 treatment group; and (6) LPS with L-NAME treatment group. The lungs were analysed by histology, NO production in the mouse lungs determined by modified Griess (Sigma-Aldrich) reaction, cytokine levels utilizing commercialkits, and protein abundance by Western blotting. RESULTS: GYY4137, a slowly-releasing H2S donor, improved the histopathological changes in the lungs of endotoxemic mice. Treatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, increased anti-oxidant biomarkers such as thetotal antioxidant capacity (T-AOC) and theactivities of catalase (CAT) and superoxide dismutase (SOD) but decreased a marker of peroxynitrite (ONOO-) action and 3-nitrotyrosine (3-NT) in endotoxemic lung. L-NAME administration also suppressed inflammation in endotoxemic lung, as evidenced by the decreased pulmonary levels of interleukin (IL)-6, IL-8, and myeloperoxidase (MPO) and the increased level of anti-inflammatory cytokine IL-10. GYY4137 treatment reversed endotoxin-induced oxidative/nitrative stress, as evidenced by a decrease in malondialdehyde (MDA), hydrogenperoxide (H2O2) and 3-NT and an increase in the antioxidant biomarker ratio of reduced/oxidized glutathione(GSH/GSSG ratio) and T-AOC, CAT and SOD activity. GYY4137 also attenuated endotoxin-induced lung inflammation. Moreover, treatment with GYY4137 inhibited inducible NOS (iNOS) expression and nitric oxide (NO) production in the endotoxemia lung. CONCLUSIONS: GYY4137 conferred protection against acute endotoxemia-associated lung injury, which may have beendue to the anti-oxidant, anti-nitrative and anti-inflammatory properties of GYY4137. The present findings warrant further exploration of the clinical applicability of H2S in the prevention and treatment of ALI.

Upregulation of microRNA-22 contributes to myocardial ischemia-reperfusion injury by interfering with the mitochondrial function.

Mitochondrial oxidative damage is critically involved in cardiac ischemia reperfusion (I/R) injury. MicroRNA-22 (miR-22) has been predicted to potentially target sirtuin-1 (Sirt1) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), both of which are known to provide protection against mitochondrial oxidative injury. The present study aims to investigate whether miR-22 is involved in the regulation of cardiac I/R injury by regulation of mitochondrial function. We found that miR-22 level was significantly increased in rat hearts subjected to I/R injury, as compared with the sham group. Intra-myocardial injection of 20 ug miR-22 inhibitor reduced I/R injury as evidenced by significant decreases in cardiac infarct size, serum lactate dehydrogenase (LDH) and creatine kinase (CK) levels and the number of apoptotic cardiomyocytes. H9c2 cardiomyocytes exposed to hypoxia/reoxygenation (H/R) insult exhibited an increase in miR-22 expression, which was blocked by reactive oxygen species (ROS) scavenger and p53 inhibitor. In addition, miR-22 inhibitor attenuated, whereas miR-22 mimic aggravated H/R-induced injury in H9c2 cardiomyocytes. MiR-22 inhibitor per se had no significant effect on cardiac mitochondrial function. Mitochondria from rat receiving miR-22 inhibitor 48h before ischemia were found to have a significantly less mitochondrial superoxide production and greater mitochondrial membrane potential and ATP production as compared with rat receiving miR control. In H9c2 cardiomyocyte, it was found that miR-22 mimic aggravated, whilst miR-22 inhibitor significantly attenuated H/R-induced mitochondrial damage. By using real time PCR, western blot and dual-luciferase reporter gene analyses, we identified Sirt1 and PGC1α as miR-22 targets in cardiomyocytes. It was found that silencing of Sirt1 abolished the protective effect of miR-22 inhibitor against H/R-induced mitochondrial dysfunction and cell injury in cardiomyocytes. Taken together, our findings reveal a novel molecular mechanism for cardiac mitochondrial dysfunction during myocardial I/R injury at the miRNA level and demonstrate the therapeutic potential of miR-22 inhibition for acute myocardial I/R injury by maintaining cardiac mitochondrial function.

Resveratrol alleviates endotoxemia-associated adrenal insufficiency by suppressing oxidative/nitrative stress.

We have recently demonstrated that endotoxin causes oxidative stress and overproduction of nitric oxide in adrenal glands, thereby leading to adrenocortical insufficiency. The aim of this study is to investigate the effects of resveratrol, a natural plant polyphenol with anti-oxidant and anti-nitrative properties, on endotoxemia-associated adrenocortical insufficiency. Resveratrol was administered immediately before injection of lipopolysaccharide (LPS). Twenty four hours later, the adrenocorticotropic hormone (ACTH) stimulation tests was been performed to measure the plasma corticosterone level and the adrenal gland tissues were collected for histopathologic examination, and determination of malondialdehyde (MDA), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, catalase (CAT) activity, inducible nitric oxide synthase (iNOS) expression, nitric oxide (NO) and peroxynitrite production. Treatment with resveratrol significantly inhibited endotoxemia-induced iNOS expression, NO production, and peroxynitrite formation and also attenuated LPS-induced oxidative stress in the adrenal gland, as evidenced by the decrease of pro-oxidant biomarker (MDA), and the increases of anti-oxidant biomarkers (T-AOC, CAT and SOD activity). H&E staining demonstrated that administration of LPS resulted in increased into the adrenal gland. H&E-stained sections of adrenal glands demonstrated signs of leukocyte infiltration and hemorrhage during endotoxemia, which were significantly improved by resveratrol treatment. In addition, resveratrol reversed the LPS-induced downregulation of ACTH receptor and silent information regulator 1 (SIRT1) in adrenal gland, as well as adrenocortical hyporesponsiveness to ACTH. Resveratrol exerts protective effects against endotoxemia-associated adrenocortical insufficiency by suppressing oxidative/nitrative stress. These findings support the potential for resveratrol as a possible pharmacological agent to improve adrenocortical insufficiency resulting from oxidative/nitrative damage.