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The International Journal of... Jul 2024Tamoxifen is an estrogen receptor modulator that has been reported to alleviate hepatic lipid accumulation in mice, but the mechanism is still unclear. Peroxisome fatty...
Tamoxifen is an estrogen receptor modulator that has been reported to alleviate hepatic lipid accumulation in mice, but the mechanism is still unclear. Peroxisome fatty acid β-oxidation is the main metabolic pathway for the overload of long-chain fatty acids. As long-chain fatty acids are a cause of hepatic lipid accumulation, the activation of peroxisome fatty acid β-oxidation might be a novel therapeutic strategy for metabolic associated fatty liver disease. In this study, we investigated the mechanism of tamoxifen against hepatic lipid accumulation based on the activation of peroxisome fatty acid β-oxidation. Tamoxifen reduced liver long-chain fatty acids and relieved hepatic lipid accumulation in high fat diet mice without sex difference. In vitro, tamoxifen protected primary hepatocytes against palmitic acid-induced lipotoxicity. Mechanistically, the RNA-sequence of hepatocytes isolated from the liver revealed that peroxisome fatty acid β-oxidation was activated by tamoxifen. Protein and mRNA expression of enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase were significantly increased in vivo and in vitro. Small interfering RNA enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase in primary hepatocytes abolished the therapeutic effects of tamoxifen in lipid accumulation. In conclusion, our results indicated that tamoxifen could relieve hepatic lipid accumulation in high fat diet mice based on the activation of enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase-mediated peroxisome fatty acids β-oxidation.
Topics: Animals; Tamoxifen; Mice; Lipid Metabolism; Liver; Hepatocytes; Oxidation-Reduction; Male; Peroxisomes; Enoyl-CoA Hydratase; Mice, Inbred C57BL; Up-Regulation; Diet, High-Fat; Female; Fatty Acids
PubMed: 38734232
DOI: 10.1016/j.biocel.2024.106585 -
Biochimica Et Biophysica Acta.... Jun 2024Peroxisomes are ubiquitous cell organelles involved in various metabolic pathways. In order to properly function, several cofactors, substrates and products of...
Peroxisomes are ubiquitous cell organelles involved in various metabolic pathways. In order to properly function, several cofactors, substrates and products of peroxisomal enzymes need to pass the organellar membrane. So far only a few transporter proteins have been identified. We analysed peroxisomal membrane fractions purified from the yeast Hansenula polymorpha by untargeted label-free quantitation mass spectrometry. As expected, several known peroxisome-associated proteins were enriched in the peroxisomal membrane fraction. In addition, several other proteins were enriched, including mitochondrial transport proteins. Localization studies revealed that one of them, the mitochondrial phosphate carrier Mir1, has a dual localization on mitochondria and peroxisomes. To better understand the molecular mechanisms of dual sorting, we localized Mir1 in cells lacking Pex3 or Pex19, two peroxins that play a role in targeting of peroxisomal membrane proteins. In these cells Mir1 only localized to mitochondria, indicating that Pex3 and Pex19 are required to sort Mir1 to peroxisomes. Analysis of the localization of truncated versions of Mir1 in wild-type H. polymorpha cells revealed that most of them localized to mitochondria, but only one, consisting of the transmembrane domains 3-6, was peroxisomal. Peroxisomal localization of this construct was lost in a MIR1 deletion strain, indicating that full-length Mir1 was required for the localization of the truncated protein to peroxisomes. Our data suggest that only full-length Mir1 sorts to peroxisomes, while Mir1 contains multiple regions with mitochondrial sorting information. Data are available via ProteomeXchange with identifier PXD050324.
Topics: Peroxisomes; Mitochondria; Fungal Proteins; Pichia; Membrane Proteins; Peroxins; Mitochondrial Proteins; Protein Transport
PubMed: 38702017
DOI: 10.1016/j.bbamcr.2024.119742 -
Biology Open May 2024Pex23 family proteins localize to the endoplasmic reticulum and play a role in peroxisome and lipid body formation. The yeast Hansenula polymorpha contains four members:...
Pex23 family proteins localize to the endoplasmic reticulum and play a role in peroxisome and lipid body formation. The yeast Hansenula polymorpha contains four members: Pex23, Pex24, Pex29 and Pex32. We previously showed that loss of Pex24 or Pex32 results in severe peroxisomal defects, caused by reduced peroxisome-endoplasmic reticulum contact sites. We now analyzed the effect of the absence of all four Pex23 family proteins on other cell organelles. Vacuoles were normal in all four deletion strains. The number of lipid droplets was reduced in pex23 and pex29, but not in pex24 and pex32 cells, indicating that peroxisome and lipid droplet formation require different Pex23 family proteins in H. polymorpha. In pex23 and pex29 cells mitochondria were fragmented and clustered accompanied by reduced levels of the fusion protein Fzo1. Deletion of DNM1 suppressed the morphological phenotype of pex23 and pex29 cells, suggesting that mitochondrial fusion is affected. pex23 and pex29 cells showed retarded growth and reduced mitochondrial activities. The growth defect was partially suppressed by DNM1 deletion as well as by an artificial mitochondrion-endoplasmic reticulum tether. Hence, the absence of Pex23 family proteins may influence mitochondrion-endoplasmic reticulum contact sites.
Topics: Mitochondria; Endoplasmic Reticulum; Pichia; Peroxins; Peroxisomes; Gene Deletion; Fungal Proteins; Membrane Proteins; Vacuoles; Phenotype
PubMed: 38682287
DOI: 10.1242/bio.060271 -
PLoS Biology Apr 2024Mitofusins are large GTPases that trigger fusion of mitochondrial outer membranes. Similarly to the human mitofusin Mfn2, which also tethers mitochondria to the...
Mitofusins are large GTPases that trigger fusion of mitochondrial outer membranes. Similarly to the human mitofusin Mfn2, which also tethers mitochondria to the endoplasmic reticulum (ER), the yeast mitofusin Fzo1 stimulates contacts between Peroxisomes and Mitochondria when overexpressed. Yet, the physiological significance and function of these "PerMit" contacts remain unknown. Here, we demonstrate that Fzo1 naturally localizes to peroxisomes and promotes PerMit contacts in physiological conditions. These contacts are regulated through co-modulation of Fzo1 levels by the ubiquitin-proteasome system (UPS) and by the desaturation status of fatty acids (FAs). Contacts decrease under low FA desaturation but reach a maximum during high FA desaturation. High-throughput genetic screening combined with high-resolution cellular imaging reveal that Fzo1-mediated PerMit contacts favor the transit of peroxisomal citrate into mitochondria. In turn, citrate enters the TCA cycle to stimulate the mitochondrial membrane potential and maintain efficient mitochondrial fusion upon high FA desaturation. These findings thus unravel a mechanism by which inter-organelle contacts safeguard mitochondrial fusion.
Topics: Peroxisomes; Mitochondrial Dynamics; Mitochondria; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Fatty Acids; GTP Phosphohydrolases; Mitochondrial Proteins; Endoplasmic Reticulum; Membrane Proteins; Proteasome Endopeptidase Complex; Citric Acid Cycle; Membrane Potential, Mitochondrial; Mitochondrial Membranes; Humans
PubMed: 38669296
DOI: 10.1371/journal.pbio.3002602 -
International Journal For Parasitology Jul 2024Nearly all aerobic organisms are equipped with catalases, powerful enzymes scavenging hydrogen peroxide and facilitating defense against harmful reactive oxygen species....
Nearly all aerobic organisms are equipped with catalases, powerful enzymes scavenging hydrogen peroxide and facilitating defense against harmful reactive oxygen species. In trypanosomatids, this enzyme was not present in the common ancestor, yet it had been independently acquired by different lineages of monoxenous trypanosomatids from different bacteria at least three times. This observation posited an obvious question: why was catalase so "sought after" if many trypanosomatid groups do just fine without it? In this work, we analyzed subcellular localization and function of catalase in Leptomonas seymouri. We demonstrated that this enzyme is present in the cytoplasm and a subset of glycosomes, and that its cytoplasmic retention is HO-dependent. The ablation of catalase in this parasite is not detrimental in vivo, while its overexpression resulted in a substantially higher parasite load in the experimental infection of Dysdercus peruvianus. We propose that the capacity of studied flagellates to modulate the catalase activity in the midgut of its insect host facilitates their development and protects them from oxidative damage at elevated temperatures.
Topics: Catalase; Animals; Trypanosomatina; Hydrogen Peroxide; Cytoplasm; Microbodies
PubMed: 38663543
DOI: 10.1016/j.ijpara.2024.04.007 -
Journal For Immunotherapy of Cancer Apr 2024While immunotherapy has been highly successful for the treatment of some cancers, for others, the immune response to tumor antigens is weak leading to treatment failure....
BACKGROUND
While immunotherapy has been highly successful for the treatment of some cancers, for others, the immune response to tumor antigens is weak leading to treatment failure. The resistance of tumors to checkpoint inhibitor therapy may be caused by T cell exhaustion resulting from checkpoint activation.
METHODS
In this study, lentiviral vectors that expressed T cell epitopes of an experimentally introduced tumor antigen, ovalbumin, or the endogenous tumor antigen, Trp1 were developed. The vectors coexpressed CD40 ligand (CD40L), which served to mature the dendritic cells (DCs), and a soluble programmed cell death protein 1 (PD-1) microbody to prevent checkpoint activation. Vaccination of mice bearing B16.OVA melanomas with vector-transduced DCs induced the proliferation and activation of functional, antigen-specific, cytolytic CD8 T cells.
RESULTS
Vaccination induced the expansion of CD8 T cells that infiltrated the tumors to suppress tumor growth. Vector-encoded CD40L and PD-1 microbody increased the extent of tumor growth suppression. Adoptive transfer demonstrated that the effect was mediated by CD8 T cells. Direct injection of the vector, without the need for ex vivo transduction of DCs, was also effective.
CONCLUSIONS
This study suggests that therapeutic vaccination that induces tumor antigen-specific CD8 T cells coupled with a vector-expressed checkpoint inhibitor can be an effective means to suppress the growth of tumors that are resistant to conventional immunotherapy.
Topics: Animals; Mice; Cancer Vaccines; Lentivirus; Immune Checkpoint Inhibitors; Humans; Dendritic Cells; Disease Models, Animal; CD8-Positive T-Lymphocytes; Melanoma, Experimental; Cell Line, Tumor; Mice, Inbred C57BL; Female
PubMed: 38658032
DOI: 10.1136/jitc-2023-008761 -
Scientific Reports Apr 2024The Eocene Geiseltal Konservat-Lagerstätte (Germany) is famous for reports of three dimensionally preserved soft tissues with sub-cellular detail. The proposed mode of...
The Eocene Geiseltal Konservat-Lagerstätte (Germany) is famous for reports of three dimensionally preserved soft tissues with sub-cellular detail. The proposed mode of preservation, direct replication in silica, is not known in other fossils and has not been verified using modern approaches. Here, we investigated the taphonomy of the Geiseltal anurans using diverse microbeam imaging and chemical analytical techniques. Our analyses confirm the preservation of soft tissues in all body regions but fail to yield evidence for silicified soft tissues. Instead, the anuran soft tissues are preserved as two layers that differ in microstructure and composition. Layer 1 comprises sulfur-rich carbonaceous microbodies interpreted as melanosomes. Layer 2 comprises the mid-dermal Eberth-Katschenko layer, preserved in calcium phosphate. In addition, patches of original aragonite crystals define the former position of the endolymphatic sac. The primary modes of soft tissue preservation are therefore sulfurization of melanosomes and phosphatization of more labile soft tissues, i.e., skin. This is consistent with the taphonomy of vertebrates in many other Konservat-Lagerstätten. These findings emphasize an emerging model for pervasive preservation of vertebrate soft tissues via melanosome films, particularly in stagnation-type deposits, with phosphatization of more labile tissues where tissue biochemistry is favorable.
Topics: Fossils; Animals; Anura; Germany; Melanosomes
PubMed: 38654038
DOI: 10.1038/s41598-024-55822-y -
Cellular and Molecular Life Sciences :... Apr 2024The high-protein diet (HPD) has emerged as a potent dietary approach to curb obesity. Peroxisome, a highly malleable organelle, adapts to nutritional changes to maintain...
The high-protein diet (HPD) has emerged as a potent dietary approach to curb obesity. Peroxisome, a highly malleable organelle, adapts to nutritional changes to maintain homeostasis by remodeling its structure, composition, and quantity. However, the impact of HPD on peroxisomes and the underlying mechanism remains elusive. Using Drosophila melanogaster as a model system, we discovered that HPD specifically increases peroxisome levels within the adipose tissues. This HPD-induced peroxisome elevation is attributed to cysteine and methionine by triggering the expression of CG33474, a fly homolog of mammalian PEX11G. Both the overexpression of Drosophila CG33474 and human PEX11G result in increased peroxisome size. In addition, cysteine and methionine diets both reduce lipid contents, a process that depends on the presence of CG33474. Furthermore, CG33474 stimulates the breakdown of neutral lipids in a cell-autonomous manner. Moreover, the expression of CG33474 triggered by cysteine and methionine requires TOR signaling. Finally, we found that CG33474 promotes inter-organelle contacts between peroxisomes and lipid droplets (LDs), which might be a potential mechanism for CG33474-induced fat loss. In summary, our findings demonstrate that CG33474/PEX11G may serve as an essential molecular bridge linking HPD to peroxisome dynamics and lipid metabolism.
Topics: Animals; Methionine; Peroxisomes; Drosophila Proteins; Drosophila melanogaster; Cysteine; Adipose Tissue; Humans; Lipid Metabolism; Lipid Droplets; Signal Transduction; Diet
PubMed: 38649521
DOI: 10.1007/s00018-024-05226-y -
Nature Communications Apr 2024Import of proteins into peroxisomes depends on PEX5, PEX13 and PEX14. By combining biochemical methods and structural biology, we show that the C-terminal SH3 domain of...
Import of proteins into peroxisomes depends on PEX5, PEX13 and PEX14. By combining biochemical methods and structural biology, we show that the C-terminal SH3 domain of PEX13 mediates intramolecular interactions with a proximal FxxxF motif. The SH3 domain also binds WxxxF peptide motifs in the import receptor PEX5, demonstrating evolutionary conservation of such interactions from yeast to human. Strikingly, intramolecular interaction of the PEX13 FxxxF motif regulates binding of PEX5 WxxxF/Y motifs to the PEX13 SH3 domain. Crystal structures reveal how FxxxF and WxxxF/Y motifs are recognized by a non-canonical surface on the SH3 domain. The PEX13 FxxxF motif also mediates binding to PEX14. Surprisingly, the potential PxxP binding surface of the SH3 domain does not recognize PEX14 PxxP motifs, distinct from its yeast ortholog. Our data show that the dynamic network of PEX13 interactions with PEX5 and PEX14, mediated by diaromatic peptide motifs, modulates peroxisomal matrix import.
Topics: Humans; Membrane Proteins; Peptides; Peroxisome-Targeting Signal 1 Receptor; Peroxisomes; Protein Binding; Protein Transport; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; src Homology Domains
PubMed: 38632234
DOI: 10.1038/s41467-024-47605-w -
BMC Genomics Apr 2024Genetically modified (GM) crop plants with transgenic expression of Bacillus thuringiensis (Bt) pesticidal proteins are used to manage feeding damage by pest insects....
BACKGROUND
Genetically modified (GM) crop plants with transgenic expression of Bacillus thuringiensis (Bt) pesticidal proteins are used to manage feeding damage by pest insects. The durability of this technology is threatened by the selection for resistance in pest populations. The molecular mechanism(s) involved in insect physiological response or evolution of resistance to Bt is not fully understood.
RESULTS
To investigate the response of a susceptible target insect to Bt, the soybean pod borer, Leguminivora glycinivorella (Lepidoptera: Tortricidae), was exposed to soybean, Glycine max, expressing Cry1Ac pesticidal protein or the non-transgenic parental cultivar. Assessment of larval changes in gene expression was facilitated by a third-generation sequenced and scaffolded chromosome-level assembly of the L. glycinivorella genome (657.4 Mb; 27 autosomes + Z chromosome), and subsequent structural annotation of 18,197 RefSeq gene models encoding 23,735 putative mRNA transcripts. Exposure of L. glycinivorella larvae to transgenic Cry1Ac G. max resulted in prediction of significant differential gene expression for 204 gene models (64 up- and 140 down-regulated) and differential splicing among isoforms for 10 genes compared to unexposed cohorts. Differentially expressed genes (DEGs) included putative peritrophic membrane constituents, orthologs of Bt receptor-encoding genes previously linked or associated with Bt resistance, and those involved in stress responses. Putative functional Gene Ontology (GO) annotations assigned to DEGs were significantly enriched for 36 categories at GO level 2, respectively. Most significantly enriched cellular component (CC), biological process (BP), and molecular function (MF) categories corresponded to vacuolar and microbody, transport and metabolic processes, and binding and reductase activities. The DEGs in enriched GO categories were biased for those that were down-regulated (≥ 0.783), with only MF categories GTPase and iron binding activities were bias for up-regulation genes.
CONCLUSIONS
This study provides insights into pathways and processes involved larval response to Bt intoxication, which may inform future unbiased investigations into mechanisms of resistance that show no evidence of alteration in midgut receptors.
Topics: Animals; Larva; Glycine max; Pesticides; Endotoxins; Bacillus thuringiensis Toxins; Bacterial Proteins; Pest Control, Biological; Moths; Bacillus thuringiensis; Chromosomes; Hemolysin Proteins; Plants, Genetically Modified; Insecticide Resistance
PubMed: 38594617
DOI: 10.1186/s12864-024-10216-2