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Biology Apr 2024Europium is one of the most reactive lanthanides and humans use it in many different applications, but we still know little about its potential toxicity and cellular...
Europium is one of the most reactive lanthanides and humans use it in many different applications, but we still know little about its potential toxicity and cellular response to its exposure. Two strains of the eukaryotic microorganism model were adapted to high concentrations of two Eu(III) compounds (EuCl or EuO) and compared to a control strain and cultures treated with both compounds. In this ciliate, EuCl is more toxic than EuO. LC values show that this microorganism is more resistant to these Eu(III) compounds than other microorganisms. Oxidative stress originated mainly by EuO is minimized by overexpression of genes encoding important antioxidant enzymes. The overexpression of metallothionein genes under treatment with Eu(III) compounds supports the possibility that this lanthanide may interact with the -SH groups of the cysteine residues from metallothioneins and/or displace essential cations of these proteins during their homeostatic function. Both lipid metabolism (lipid droplets fusing with europium-containing vacuoles) and autophagy are involved in the cellular response to europium stress. Bioaccumulation, together with a possible biomineralization to europium phosphate, seems to be the main mechanism of Eu(III) detoxification in these cells.
PubMed: 38785768
DOI: 10.3390/biology13050285 -
Biology Apr 2024Adipose tissue plays an important role in regulating body temperature and metabolism, with white adipocytes serving as storage units for energy. Recent research focused...
Adipose tissue plays an important role in regulating body temperature and metabolism, with white adipocytes serving as storage units for energy. Recent research focused on the browning of white adipocytes (beige adipocytes), causing thermogenesis and lipolysis. The process of browning is linked to the activation of uncoupling protein (UCP) expression, which can be mediated by the β3 adrenergic receptor pathway. Transcriptional factors, such as peroxisome proliferator activated receptor γ () and PPARγ coactivator 1 alpha, play vital roles in cell fate determination for fat cells. Beige adipocytes have metabolic therapeutic potential to combat diseases such as obesity, diabetes mellitus, and dyslipidemia, owing to their significant impact on metabolic functions. However, the molecular mechanisms that cause the induction of browning are unclear. Therefore, research using animal models and primary culture is essential to provide an understanding of browning for further application in human metabolic studies. Pigs have physiological similarities to humans; hence, they are valuable models for research on adipose tissue. This study demonstrates the browning potential of pig white adipocytes through primary culture experiments. The results show that upregulation of gene expression and fragmentation of lipid droplets into smaller particles occur due to isoproterenol stimulation, which activates beta-adrenergic receptor signaling. Furthermore, and were found to activate the UCP3 promoter region, similar to that of UCP1. These findings suggest that pigs undergo metabolic changes that induce browning in white adipocytes, providing a promising approach for metabolic research with potential implications for human health. This study offers valuable insights into the mechanism of adipocyte browning using pig primary culture that can enhance our understanding of human metabolism, leading to cures for commonly occurring diseases.
PubMed: 38785767
DOI: 10.3390/biology13050284 -
Molecular Biomedicine May 2024Carcinoembryonic antigen (CEA) is a tumor-associated antigen primarily produced by tumor cells. It has been implicated in various biological processes such as cell...
Carcinoembryonic antigen (CEA) is a tumor-associated antigen primarily produced by tumor cells. It has been implicated in various biological processes such as cell adhesion, proliferation, differentiation, and metastasis. Despite this, the precise molecular mechanisms through which CEA enhances tumor cell proliferation remain largely unclear. Our study demonstrates that CEA enhances the proliferation and migration of non-small cell lung cancer (NSCLC) while also inhibiting cisplatin-induced apoptosis in NSCLC cells. Treatment with CEA led to an increase in mitochondrial numbers and accumulation of lipid droplets in A549 and H1299 cells. Additionally, our findings indicate that CEA plays a role in regulating the fatty acid metabolism of NSCLC cells. Inhibiting fatty acid metabolism significantly reduced the CEA-mediated proliferation and migration of NSCLC cells. CEA influences fatty acid metabolism and the proliferation of NSCLC cells by activating the PGC-1α signaling pathway. This regulatory mechanism involves CEA increasing intracellular cAMP levels, which in turn activates PKA and upregulates PGC-1α. In NSCLC, inhibiting the PKA-PGC-1α signaling pathway reduces both fatty acid metabolism and the proliferation and migration induced by CEA, both in vitro and in vivo. These results suggest that CEA contributes to the promotion of proliferation and migration by modulating fatty acid metabolism. Targeting CEA or the PKA-PGC-1ɑ signaling pathway may offer a promising therapeutic approach for treating NSCLC.
Topics: Carcinoma, Non-Small-Cell Lung; Humans; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Carcinoembryonic Antigen; Lung Neoplasms; Cell Proliferation; Cell Line, Tumor; Cell Movement; Cyclic AMP-Dependent Protein Kinases; Animals; Signal Transduction; Disease Progression; Mice; Apoptosis; Fatty Acids
PubMed: 38782774
DOI: 10.1186/s43556-024-00181-3 -
Hepatology Communications Jun 2024Previous reports suggest that lipid droplets (LDs) in the hepatocyte can be catabolized by a direct engulfment from nearby endolysosomes (microlipophagy). Further, it is...
BACKGROUND
Previous reports suggest that lipid droplets (LDs) in the hepatocyte can be catabolized by a direct engulfment from nearby endolysosomes (microlipophagy). Further, it is likely that this process is compromised by chronic ethanol (EtOH) exposure leading to hepatic steatosis. This study investigates the hepatocellular machinery supporting microlipophagy and EtOH-induced alterations in this process with a focus on the small, endosome-associated, GTPase Rab5.
METHODS AND RESULTS
Here we report that this small Ras-related GTPase is a resident component of LDs, and its activity is important for hepatocellular LD-lysosome proximity and physical interactions. We find that Rab5 siRNA knockdown causes an accumulation of LDs in hepatocytes by inhibiting lysosome dependent LD catabolism. Importantly, Rab5 appears to support this process by mediating the recruitment of early endosomal and or multivesicular body compartments to the LD surface before lysosome fusion. Interestingly, while wild-type or a constituently active GTPase form (Q79L) of Rab5 supports LD-lysosome transport, this process is markedly reduced in cells expressing a GTPase dead (S34N) Rab5 protein or in hepatocytes exposed to chronic EtOH.
CONCLUSIONS
These findings support the novel premise of an early endosomal/multivesicular body intermediate compartment on the LD surface that provides a "docking" site for lysosomal trafficking, not unlike the process that occurs during the hepatocellular degradation of endocytosed ligands that is also known to be compromised by EtOH exposure.
Topics: rab5 GTP-Binding Proteins; Lysosomes; Ethanol; Hepatocytes; Humans; Lipid Droplets; Autophagy; Animals; Endosomes
PubMed: 38780316
DOI: 10.1097/HC9.0000000000000446 -
Biochemical and Biophysical Research... Aug 2024Prader-Willi syndrome (PWS) is a complex epigenetic disorder caused by the deficiency of paternally expressed genes in chromosome 15q11-q13. This syndrome also includes...
Prader-Willi syndrome (PWS) is a complex epigenetic disorder caused by the deficiency of paternally expressed genes in chromosome 15q11-q13. This syndrome also includes endocrine dysfunction, leading to short stature, hypogonadism, and obscure hyperphagia. Although recent progress has been made toward understanding the genetic basis for PWS, the molecular mechanisms underlying its pathology in obesity remain unclear. In this study, we examined the adipocytic characteristics of two PWS-induced pluripotent stem cell (iPSC) lines: those with the 15q11-q13 gene deletion (iPWS cells) and those with 15q11-q13 abnormal methylation (M-iPWS cells). The transcript levels of the lipid-binding protein aP2 were decreased in iPWS and M-iPWS adipocytes. Flow-cytometry analysis showed that PWS adipocytes accumulated more lipid droplets than did normal individual adipocytes. Furthermore, glucose uptake upon insulin stimulation was attenuated compared to that in normal adipocytes. Overall, our results suggest a significantly increased lipid content and defective in glucose metabolism in PWS adipocytes.
Topics: Prader-Willi Syndrome; Adipocytes; Humans; Induced Pluripotent Stem Cells; Glucose; Chromosomes, Human, Pair 15; Fatty Acid-Binding Proteins; Cell Line; DNA Methylation; Gene Deletion; Lipid Metabolism; Insulin
PubMed: 38776833
DOI: 10.1016/j.bbrc.2024.150124 -
Biophysics Reports Apr 2024The lipid droplet (LD) is a conserved organelle that exists in almost all organisms, ranging from bacteria to mammals. Dysfunctions in LDs are linked to a range of human...
The lipid droplet (LD) is a conserved organelle that exists in almost all organisms, ranging from bacteria to mammals. Dysfunctions in LDs are linked to a range of human metabolic syndromes. The formation of protein complexes on LDs is crucial for maintaining their function. Investigating how proteins interact on LDs is essential for understanding the role of LDs. We have developed an effective method to uncover protein-protein interactions and protein complexes specifically on LDs. In this method, we conduct co-immunoprecipitation (co-IP) experiments using LD proteins extracted directly from isolated LDs, rather than utilizing proteins from cell lysates. To elaborate, we begin by purifying LDs with high-quality and extracting LD-associated proteins. Subsequently, the co-IP experiment is performed on these LD-associated proteins directly, which would enhance the co-IP experiment specificity of LD-associated proteins. This method enables researchers to directly unveil protein complexes on LDs and gain deeper insights into the functional roles of proteins associated with LDs.
PubMed: 38774355
DOI: 10.52601/bpr.2024.240007 -
Cell Death & Disease May 2024Seipin is one key mediator of lipid metabolism that is highly expressed in adipose tissues as well as in the brain. Lack of Seipin gene, Bscl2, leads to not only severe...
Seipin is one key mediator of lipid metabolism that is highly expressed in adipose tissues as well as in the brain. Lack of Seipin gene, Bscl2, leads to not only severe lipid metabolic disorders but also cognitive impairments and motor disabilities. Myelin, composed mainly of lipids, facilitates nerve transmission and is important for motor coordination and learning. Whether Seipin deficiency-leaded defects in learning and motor coordination is underlined by lipid dysregulation and its consequent myelin abnormalities remains to be elucidated. In the present study, we verified the expression of Seipin in oligodendrocytes (OLs) and their precursors, oligodendrocyte precursor cells (OPCs), and demonstrated that Seipin deficiency compromised OPC differentiation, which led to decreased OL numbers, myelin protein, myelinated fiber proportion and thickness of myelin. Deficiency of Seipin resulted in impaired spatial cognition and motor coordination in mice. Mechanistically, Seipin deficiency suppressed sphingolipid metabolism-related genes in OPCs and caused morphological abnormalities in lipid droplets (LDs), which markedly impeded OPC differentiation. Importantly, rosiglitazone, one agonist of PPAR-gamma, substantially restored phenotypes resulting from Seipin deficiency, such as aberrant LDs, reduced sphingolipids, obstructed OPC differentiation, and neurobehavioral defects. Collectively, the present study elucidated how Seipin deficiency-induced lipid dysregulation leads to neurobehavioral deficits via impairing myelination, which may pave the way for developing novel intervention strategy for treating metabolism-involved neurological disorders.
Topics: Animals; GTP-Binding Protein gamma Subunits; Cell Differentiation; Mice; Oligodendrocyte Precursor Cells; Myelin Sheath; Cognitive Dysfunction; Lipid Metabolism; Oligodendroglia; Mice, Inbred C57BL; PPAR gamma; Mice, Knockout; Male; Rosiglitazone
PubMed: 38773070
DOI: 10.1038/s41419-024-06737-z -
Langmuir : the ACS Journal of Surfaces... Jun 2024Model bilayers are constructed from lipids having different intrinsic curvatures using the droplet interface bilayer (DIB) method, and their static physicochemical...
Model bilayers are constructed from lipids having different intrinsic curvatures using the droplet interface bilayer (DIB) method, and their static physicochemical properties are determined. Geometrical and tensiometric measurements are used to derive the free energy of formation (ΔF) of a two-droplet DIB relative to a pair of isolated aqueous droplets, each decorated with a phospholipid monolayer. The lipid molecules employed have different headgroup sizes but identical hydrophobic tail structure, and each is characterized by an intrinsic curvature value () that increases in absolute value with decreasing size of headgroup. Mixtures of lipids at different ratios were also investigated. The role of curvature stress on the values of ΔF of the respective lipid bilayers in these model membranes is discussed and is illuminated by the observation of a decrement in ΔF that scales as a near linear function of . Overall, the results reveal an association that should prove useful in studies of ion channels and other membrane proteins embedded in model droplet bilayer systems that will impact the understanding of protein function in cellular membranes composed of lipids of high and low curvature.
Topics: Lipid Bilayers; Phospholipids
PubMed: 38764431
DOI: 10.1021/acs.langmuir.4c00270 -
Biochimica Et Biophysica Acta.... Aug 2024Excess cholesterol storage can induce the formation of cholesterol crystals in hepatocyte lipid droplets. Such crystals distinguish metabolic dysfunction associated...
OBJECTIVE
Excess cholesterol storage can induce the formation of cholesterol crystals in hepatocyte lipid droplets. Such crystals distinguish metabolic dysfunction associated steatohepatitis (MASH) from simple steatosis and may underlie its pathogenesis by causing cell damage that triggers liver inflammation. The mechanism linking cholesterol excess to its crystallization in lipid droplets is unclear. As cholesteryl esters localize to and accumulate in lipid droplets more readily than unesterified free cholesterol, we investigated whether cholesterol esterification by sterol O-acyltransferase (SOAT), also known as acyl co-A cholesterol acyltransferase (ACAT), is required for hepatocyte lipid droplet crystal formation.
METHOD
Cholesterol crystals were measured in cholesterol loaded Hep3B hepatocytes, RAW264.7 macrophages, and mouse liver using polarizing light microscopy. We examined the effect of blocking SOAT activity on crystal formation and compared these results to features of cholesterol metabolism and the progression to intracellular crystal deposits.
RESULTS
Cholesterol loading of Hep3B cells caused robust levels of lipid droplet localized crystal formation in a dose- and time-dependent manner. Co-treatment with SOAT inhibitors and genetic ablation of SOAT1 blocked crystal formation. SOAT inhibitor also blocked crystal formation in low density lipoprotein (LDL) treated Hep3B cells, acetylated LDL treated RAW 264.7 macrophages, and in the liver of mice genetically predisposed to hepatic cholesterol overload and in mice with cholesterol enriched diet-induced MASH.
CONCLUSION
SOAT1-mediated esterification may underlie cholesterol crystals associated with MASH by concentrating it in lipid droplets. These findings imply that inhibiting hepatocyte SOAT1 may be able to alleviate cholesterol associated MASH. Moreover, that either a lipid droplet localized cholesteryl ester hydrolase is required for cholesterol crystal formation, or the crystals are composed of cholesteryl ester.
Topics: Animals; Humans; Male; Mice; Cholesterol; Cholesterol Esters; Crystallization; Esterification; Hepatocytes; Lipid Droplets; Liver; Mice, Inbred C57BL; RAW 264.7 Cells; Sterol O-Acyltransferase
PubMed: 38761895
DOI: 10.1016/j.bbalip.2024.159512 -
Communications Biology May 2024Non-alcoholic fatty liver disease (NAFLD) is a chronic disease caused by hepatic steatosis. Adenosine deaminases acting on RNA (ADARs) catalyze adenosine to inosine RNA...
Non-alcoholic fatty liver disease (NAFLD) is a chronic disease caused by hepatic steatosis. Adenosine deaminases acting on RNA (ADARs) catalyze adenosine to inosine RNA editing. However, the functional role of ADAR2 in NAFLD is unclear. ADAR2/GluR-B mice (wild type, WT) and ADAR2/GluR-B mice (ADAR2 KO) mice are fed with standard chow or high-fat diet (HFD) for 12 weeks. ADAR2 KO mice exhibit protection against HFD-induced glucose intolerance, insulin resistance, and dyslipidemia. Moreover, ADAR2 KO mice display reduced liver lipid droplets in concert with decreased hepatic TG content, improved hepatic insulin signaling, better pyruvate tolerance, and increased glycogen synthesis. Mechanistically, ADAR2 KO effectively mitigates excessive lipid production via AMPK/Sirt1 pathway. ADAR2 KO inhibits hepatic gluconeogenesis via the AMPK/CREB pathway and promotes glycogen synthesis by activating the AMPK/GSK3β pathway. These results provide evidence that ADAR2 KO protects against NAFLD progression through the activation of AMPK signaling pathways.
Topics: Animals; Adenosine Deaminase; RNA-Binding Proteins; Signal Transduction; Mice; Mice, Knockout; Non-alcoholic Fatty Liver Disease; Diet, High-Fat; Male; AMP-Activated Protein Kinases; Insulin Resistance; Mice, Obese; Obesity; Mice, Inbred C57BL; Liver
PubMed: 38760406
DOI: 10.1038/s42003-024-06215-4