CD36 Expression Research Articles

CD69 marks a subpopulation of acute myeloid leukemia with enhanced colony forming capacity and a unique signaling activation state

In acute myeloid leukemia (AML), leukemia stem cells (LSCs) have self-renewal potential and are responsible for relapse. We previously showed that, in Mll-AF9/NRASG12V murine AML, CD69 expression marks an LSC-enriched subpopulation with enhanced in vivo self-renewal capacity. Here, we used CyTOF to define activated signaling pathways in LSC subpopulations in Mll-AF9/NRASG12V AML. Furthermore, we compared the signaling activation states of CD69High and CD36High subsets of primary human AML. The human CD69High subset expresses low levels of Ki67 and high levels of NFκB and pMAPKAPKII. Additionally, the human CD69High AML subset also has enhanced colony-forming capacity. We applied Bayesian network modeling to compare the global signaling network within the human AML subsets. We find that distinct signaling states, distinguished by NFκB and pMAPKAPKII levels, correlate with divergent functional subsets, defined by CD69 and CD36 expression, in human AML. Targeting NFκB with proteasome inhibition diminished colony formation.

Lipid metabolism marker CD36 is associated with 18FDG-PET/CT false negative lymph nodes in head and neck squamous cell carcinoma.

Lymph node metastasis frequently occurs in head and neck squamous cell carcinoma (HNSCC) patients, and [18F] fluorodeoxyglucose positron emission tomography with computed tomography (18FDG-PET/CT) examination for lymph node metastasis could result in false negativity and delay following treatment. However, the mechanism and resolution for 18FDG-PET/CT false negatives remain unclear. Our study was aim to found biomarkers for false negativity and true positivity from a metabolic perspective. Ninety-two patients diagnosed with HNSCC who underwent preoperative 18FDG-PET/CT and subsequent surgery in our institution were reviewed. Immunohistochemistry (IHC) examinations of glucose metabolism (GLUT1 and GLUT5), amino acid metabolism4 (GLS and SLC1A5), and lipid metabolism (CPT1A and CD36) markers were conducted on their primary lesion and lymph node sections. We identified specific metabolic patterns of the false-negative group. Significantly, CD36 IHC score of primary lesions was higher in false-negative group than true-positive group. Moreover, we validated pro-invasive biological effects of CD36 by bioinformatics analysis as well as experiments. Conclusion: IHC examination of CD36 expression, which is a lipid metabolism marker, in primary lesions could distinguish HNSCC patients' lymph nodes false negatives in 18FDG-PET/CT.

Understanding Long-Term Survival of Patients with Ovarian Cancer—The Tumor Microenvironment Comes to the Forefront

High-grade serous ovarian cancer (HGSOC) is the deadliest subtype of ovarian cancer, and most patients do not survive more than 5 years after diagnosis. Yet, for reasons that are often elusive, approximately 15% of women with advanced-stage HGSOC will survive longer than 10 years. An understanding of the biological basis of long-term survival with HGSOC may elucidate novel prognostic factors and targets for treatment. Past analyses of the clinicopathologic features of these women and genetic profiles of their tumors have not revealed a unifying explanation for their increased longevity. In this issue of Cancer Research, Ferri-Borgogno and colleagues investigate the tumor microenvironment (TME) in samples from both long- and short-term survivors using spatial transcriptomics and single-cell RNA sequencing. They found that, in metastatic tumors, various populations of cancer-associated fibroblasts (CAF) in the TME play different roles in supporting the malignant phenotype of ovarian cancer cells. Higher density of CAFs, particularly αSMA+VIM+PDGFRβ+ CAFs, was associated with lower tumor immune infiltration and short-term survival. There was also marked expression of periostin and CD36 in spatially resolved CAFs, as well as a prevalence of the APOE-LRP5 ligand-receptor pair at the tumor-stromal interface in tissue from short-term survivors. These findings suggest that, in short-term survivors, CAFs are able to more effectively promote tumorigenicity, stemness, and chemoresistance in the nearby tumor. See related article by Ferri-Borgogno et al., p. 1503.

Abstract 675: Time Restricted Feeding Regulates Cholesterol Efflux And Atherosclerosis In Macrophage-specific Bmal1 Deficient Mice

Background: Macrophages play a critical role in atherosclerosis. We have previously shown that Clock mutant and global or tissue-specific Bmal1 deficient mice show enhanced atherosclerosis. Yet, the role of time restricted feeding (TRF) in cholesterol transport and atherosclerosis in macrophage Bmal1 deficient mice remains unknown. Objectives: To establish a novel regulatory link between TRF, circadian clock, and atherosclerosis. Methods: We studied the effect of day or nighttime TRF on macrophage-specific Bmal1 deficient (M- Bmal1 –/– Apoe –/– ) or control mice on cholesterol efflux to clarify the role of Bmal1 in macrophage function and in atherosclerosis. Results: We found that daytime-TRF increased atherosclerosis. Biochemical studies showed that macrophages from daytime TRF M- Bmal1 –/– Apoe –/– mice exhibit increased expression of Lox-1 and Cd36, and take up more oxLDL compared to nighttime TRF mice. Furthermore, daytime TRF mice showed decreased expression of Abca1 and Abcg1, reduced cellular cholesterol efflux and in vivo reverse cholesterol transport compared to nighttime TRF mice. Thus, TRF regulates macrophage cholesterol metabolism by regulating uptake of oxidized lipoproteins and cholesterol efflux pathways. Molecular studies showed that TRF regulates HDAC3 interactions with p300 to regulate Znf202 gene expression. Thus, TRF regulates Bmal1 and Znf202 to regulate uptake of oxidized lipoproteins and cholesterol efflux. Conclusions: TRF is an important regulator of cholesterol metabolism in macrophages and affects atherosclerosis. It regulates macrophage function by modulating the expression of different transcription factors. It is likely that nighttime-TRF may prevent atherosclerosis.

TREM2 promotes cholesterol uptake and foam cell formation in atherosclerosis.

Disordered lipid accumulation in the arterial wall is a hallmark of atherosclerosis. Previous studies found that the expression of triggering receptor expressed on myeloid cells 2 (TREM2), a transmembrane receptor of the immunoglobulin family, is increased in mouse atherosclerotic aortic plaques. However, it remains unknown whether TREM2 plays a role in atherosclerosis. Here we investigated the role of TREM2 in atherosclerosis using ApoE knockout (ApoE-/-) mouse models, primary vascular smooth muscle cells (SMCs), and bone marrow-derived macrophages (BMDMs). In ApoE-/- mice, the density of TREM2-positive foam cells in aortic plaques increased in a time-dependent manner after the mice were fed a high-fat diet (HFD). Compared with ApoE-/- mice, the Trem2-/-/ApoE-/- double-knockout mice showed significantly reduced atherosclerotic lesion size, foam cell number, and lipid burden degree in plaques after HFD feeding. Overexpression of TREM2 in cultured vascular SMCs and macrophages exacerbates lipid influx and foam cell formation by upregulating the expression of the scavenger receptor CD36. Mechanistically, TREM2 inhibits the phosphorylation of p38 mitogen-activated protein kinase and peroxisome proliferator activated-receptor gamma (PPARγ), thereby increasing PPARγ nuclear transcriptional activity and subsequently promoting the transcription of CD36. Our results indicate that TREM2 exacerbates atherosclerosis development by promoting SMC- and macrophage-derived foam cell formation by regulating scavenger receptor CD36 expression. Thus, TREM2 may act as a novel therapeutic target for the treatment of atherosclerosis.

Mitochondrial CD36 expression is increased in endothelial cells exposed to elevated glucose in vitro

Background and Objective: Obesity is a multifactorial metabolic disease encompassing several cardiovascular risk factors including hyperglycemia. CD36 is a fatty acid translocase scavenger receptor and a glycoprotein which was previously shown to be upregulated by obesity and in response to elevated glucose. Furthermore, recent studies have identified the expression of CD36 in mitochondria of a variety of cell types which, following upregulation of mitoCD36 expression, would have significant impact on cellular respiration. Therefore, we aimed to determine the effect of elevated glucose on mitochondrial CD36 expression in endothelial cells in vitro. Methods: We treated human adipose microvascular endothelial cells (HAMECs) with high glucose (200 mg/dL) and mannitol (osmotic control; 200 mg/dL) for 24, 48, 72, or 96 hours. The control group was maintained in standard media containing 100 mg/dL glucose. Following treatments, CD36 expression was assessed via Western blot, qPCR, flow cytometry and immunocytochemistry (ICC). An antibody targeting an extracellular epitope of CD36 was used to identify membrane expression where appropriate. ICC was performed on distinct groups of nonpermeabilized and permeabilized cells to detect changes in membrane vs. internal expression, respectively. Mitochondria were isolated from HAMECs using positive selection of TOM40 via magnetic associated cell sorting. Statistics: A one-way Kruskal Wallis (p < 0.05) was used followed by Dunn Sidak post hoc tests to determine significant differences. Results: HAMECs exposed to elevated glucose exhibited an increase in CD36 expression in total cell lysates and in permeabilized cells after 72 hrs. However, no changes were detected in CD36 membrane expression or in CD36 gene expression in response to elevated glucose suggesting that internal expression of CD36 protein is increased through mechanisms independent of transcription under these conditions. To determine if CD36 expression was elevated specifically in mitochondria following exposure to elevated glucose, mitochondria were isolated and purified from HAMECs. CD36 expression was revealed to be increased in the mitochondrial fraction of glucose treated cells perhaps indicating alterations to mitochondrial respiration in the presence of sustained elevated glucose. Discussion and Conclusions: Our findings reveal that mitochondrial CD36 expression is elevated in endothelial cells exposed to sustained increases in glucose in vitro, which may impact mitochondrial respiration in the presence of other macronutrients like fatty acids. Ongoing studies in our lab are aimed at identifying the functional effects of increased mitoCD36 on endothelial cell respiration when challenged with fatty acids. This study was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under award number 2P20GM113125 (Ibra Fancher). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hepatocyte CD36 modulates UBQLN1-mediated proteasomal degradation of autophagic SNARE proteins contributing to septic liver injury

ABSTRACT Macroautophagy/autophagy plays a protective role in sepsis-induced liver injury. As a member of class B scavenger receptors, CD36 plays important roles in various disorders, such as atherosclerosis and fatty liver disease. Here we found that the expression of CD36 in hepatocytes was increased in patients and a mouse model with sepsis, accompanied by impaired autophagy flux. Furthermore, hepatocyte cd36 knockout (cd36-HKO) markedly improved liver injury and the impairment of autophagosome-lysosome fusion in lipopolysaccharide (LPS)-induced septic mice. Ubqln1 (ubiquilin 1) overexpression (OE) in hepatocyte blocked the protective effect of cd36-HKO on LPS-induced liver injury in mice. Mechanistically, with LPS stimulation, CD36 on the plasma membrane was depalmitoylated and distributed to the lysosome, where CD36 acted as a bridge molecule linking UBQLN1 to soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and hence promoting the proteasomal degradation of SNARE proteins, resulting in fusion impairment. Overall, our data reveal that CD36 is essential for modulating the proteasomal degradation of autophagic SNARE proteins in a UBQLN1-dependent manner. Targeting CD36 in hepatocytes is effective for improving autophagic flux in sepsis and therefore represents a promising therapeutic strategy for clinical treatment of septic liver injury. Abbreviations: AAV8: adeno-associated virus 8; AOSC: acute obstructive suppurative cholangitis; ATP1A1: ATPase, Na+/K+ transporting, alpha 1 polypeptide; CASP3: caspase 3; CASP8: caspase 8; CCL2: chemokine (C-C motif) ligand 2; cd36-HKO: hepatocyte-specific cd36 knockout; Co-IP: co-immunoprecipitation; CQ: chloroquine; Cys: cysteine; GOT1: glutamic-oxaloacetic transaminase 1, soluble; GPT: glutamic–pyruvic transaminase, soluble; IL1B: interleukin 1 beta; IL6: interleukin 6; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LDH, lactate dehydrogenase; LPS: lipopolysaccharide; LYPLA1: lysophospholipase 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; OE: overexpression; qPCR: quantitative polymerase chain reaction; SNAP29: synaptosome associated protein 29; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SQSTM1/p62: sequestosome 1; STX17: syntaxin 17; TNF: tumor necrosis factor; TRIM: tripartite motif-containing; UBA: ubiquitin-associated; UBL: ubiquitin-like; UBQLN: ubiquilin; VAMP8: vesicle associated membrane protein 8; WT: wild-type.

Preclinical Evaluation of CD36-Targeting Antiangiogenic Peptide ABT-510 for Near-Infrared Fluorescence Molecular Imaging of Colorectal Cancer.

Surgical resection constitutes the first choice of treatment for colorectal cancer (CRC). Despite advancements in intraoperative navigation, there remains a considerable lack of effective targeting probes for the imaging-guided surgical navigation of CRC owing to their high heterogeneity. Hence, developing a suitable fluorescent probe to detect the specific types of CRC populations is crucial. Herein, we labeled ABT-510, a small, CD36-targeting thrombospondin-1-mimetic peptide overexpressed in various cancer types, with fluorescein isothiocyanate or near-infrared dye MPA. We found that fluorescence-conjugated ABT-510 exhibited excellent selectivity and specificity toward cells or tissues with high CD36 expression. The tumor-to-colorectal signal ratios were 11.28 ± 0.61 (95% confidence interval) and 10.74 ± 0.07 (95% confidence interval) in subcutaneous HCT-116 and HT-29 tumor-bearing nude mice, respectively. Moreover, high signal contrast was observed in the orthotopic and liver metastatic CRC xenograft mouse models. Furthermore, MPA-PEG4-r-ABT-510 exhibited an antiangiogenic effect via tube information assay with human umbilical vein endothelial cells. Overall, MPA-PEG4-r-ABT-510 presents rapid and precise tumor delineation characteristics, thereby making it a desirable tool for CRC imaging and surgical navigation.

Serum level of apoptosis inhibitor of macrophage in dogs with histiocytic sarcoma and its association with the disease.

Histiocytic sarcoma (HS) is a rare neoplasm of macrophages or dendritic cells with a poor prognosis in dogs. As the apoptosis inhibitor of macrophage (AIM) is characteristically expressed in canine macrophages, we hypothesised that AIM is involved in the development or progression of HS in dogs. In this study, AIM expression in the tumour region and serum AIM levels in dogs with HS was assessed. Additionally, the effects of AIM overexpression on HS cell viability were investigated using a HS cell line that was selected from five validated HS cell lines. Immunohistochemistry showed that AIM expression was observed in the cytoplasm of the HS cells. CD36, a candidate AIM receptor, was also observed on the cell membrane of HS cells. When the serum AIM level was detected in 36 dogs with HS and 10 healthy dogs via western blot analysis, the AIM levels in the HS dogs were significantly higher than those in the controls. AIM mRNA expression in the 5 HS cell lines varied but was higher than that in the other tumour-derived lines. Among the five HS cell lines, DH82 originally had lower AIM and the highest CD36 expression. When AIM was overexpressed in DH82, therein cell growth speed and invasion, apoptosis inhibition and phagocytic activity were strongly upregulated. These data suggest that elevated intra-tumour expression of AIM could induce the progression of HS cells in dogs. Moreover, elevated serum AIM levels in dogs with HS could serve as a biomarker of HS.

Arterial wall inflammation assessed by 18F-FDG-PET/CT is higher in individuals with Type 1 diabetes and associated with circulating inflammatory proteins.

The article investigates whether chronic hyperglycaemia in Type 1 diabetes (T1D) is associated with a proinflammatory immune signature and with arterial wall inflammation, driving the development of atherosclerosis. Patients with T1D (n = 41), and healthy age-, sex-, and body mass index-matched controls (n = 20) were recruited. Arterial wall inflammation and haematopoietic activity were measured with 2'-deoxy-2'-(18F)-fluoro-D-glucose (18F-FDG) positron emission tomography/computed tomography. In addition, flow cytometry of circulating leucocytes was performed as well as targeted proteomics to measure circulating inflammatory markers. 18F-FDG uptake in the wall of the abdominal aorta, carotid arteries, and iliac arteries was higher in T1D compared with that in the healthy controls. Also, 18F-FDG uptake in the bone marrow and spleen was higher in patients with T1D. CCR2 and CD36 expressions on circulating monocytes were higher in patients with T1D, as well as several circulating inflammatory proteins. In addition, several circulating inflammatory markers (osteoprotegerin, transforming growth factor-alpha, CX3CL1, and colony-stimulating factor-1) displayed a positive correlation with FDG uptake. Within T1D, no differences were found between people with a high and low HbA1c. These findings strengthen the concept that chronic hyperglycaemia in T1D induces inflammatory changes that fuel arterial wall inflammation leading to atherosclerosis. The degree of hyperglycaemia appears to play a minor role in driving this inflammatory response in patients with T1D.

Palmitic acid-induced ferroptosis via CD36 activates ER stress to break calcium-iron balance in colon cancer cells.

Ferroptosis, featuring an iron-dependent peroxidation of lipids, is a novel form of programmed cell death that may hold great potential in cancer therapy. Our study found that palmitic acid (PA) inhibited colon cancer cell viability in vitro and in vivo, in conjunction with an accumulation of reactive oxygen species (ROS) and lipid peroxidation. The ferroptosis inhibitor Ferrostatin-1 but not Z-VAD-FMK (a pan-caspase inhibitor), Necrostatin-1 (a potent necroptosis inhibitor), or CQ (a potent inhibitor of autophagy), rescued the cell death phenotype induced by PA. Subsequently, we verified that PA induces ferroptotic cell death through excess iron as cell death was inhibited by iron chelator deferiprone (DFP), while it was exacerbated by a supplement of ferric ammonium citrate (FAC). Mechanistically, PA affects intracellular iron content by inducing endoplasmic reticulum (ER) stress leading to ER calcium release and regulating transferrin transport through increasing cytosolic calcium levels. Furthermore, we observed that cells with high expression of CD36 were more vulnerable to PA-induced ferroptosis. Altogether, our findings reveal that PA engages in anticancer properties by activating ER stress/ER calcium release/transferrin-dependent ferroptosis, and PA might serve as a compound to activate ferroptosis in colon cancer cells with high CD36 expression.

MiR-3180 inhibits hepatocellular carcinoma growth and metastasis by targeting lipid synthesis and uptake

PurposeReprogrammed lipid metabolism is a hallmark of cancer that provides energy, materials, and signaling molecules for rapid cancer cell growth. Cancer cells acquire fatty acids primarily through de novo synthesis and uptake. Targeting altered lipid metabolic pathways is a promising anticancer strategy. However, their regulators have not been fully investigated, especially those targeting both synthesis and uptake.MethodsImmunohistochemistry was performed on samples from patients with hepatocellular carcinoma (HCC) to establish the correlation between miR-3180, stearoyl-CoA desaturase-1 (SCD1), and CD36 expression, quantified via qRT-PCR and western blotting. The correlation was analyzed using a luciferase reporter assay. Cell proliferation, migration, and invasion were analyzed using CCK-8, wound healing, and transwell assays, respectively. Oil Red O staining and flow cytometry were used to detect lipids. Triglycerides and cholesterol levels were analyzed using a reagent test kit. CY3-labeled oleic acid transport was analyzed using an oleic acid transport assay. Tumor growth and metastasis were detected in vivo in a xenograft mouse model.ResultsMiR-3180 suppressed de novo fatty acid synthesis and uptake by targeting the key lipid synthesis enzyme SCD1 and key lipid transporter CD36. MiR-3180 suppressed HCC cell proliferation, migration, and invasion in an SCD1- and CD36-dependent manner in vitro. The mouse model demonstrated that miR-3180 inhibits HCC tumor growth and metastasis by inhibiting SCD1- and CD36-mediated de novo fatty acid synthesis and uptake. MiR-3180 expression was downregulated in HCC tissues and negatively correlated with SCD1 and CD36 levels. Patients with high miR-3180 levels showed better prognosis than those with low levels.ConclusionsOur investigation indicates that miR-3180 is a critical regulator involved in de novo fatty acid synthesis and uptake, which inhibits HCC tumor growth and metastasis by suppressing SCD1 and CD36. Therefore, miR-3180 is a novel therapeutic target and prognostic indicator for patients with HCC.

Abstract 5952: Pyroptotic adipocytes contribute to chemoresistance in advanced stage ovarian cancer

Abstract Background: Ovarian cancer is known the gynecologic malignancy with the highest case-to-fatality ratio. Once appear metastasis, the 5 years survival rate reduce to 30-40% in these patients. Different with hematogenously metastasizing tumors, ovarian cancer cells primarily disseminate within the peritoneal cavity. Omentum, a lipid-rich tissue, is the most common metastatic site of ovarian cancer. In addition, the adipocyte-released free fatty acid can be used by cancer cells to fuel its growth and proliferation. In this study, we attempt to clarify the regulation between metastatic ovarian cancer cell and omental adipocytes, and find a therapeutic strategy for advanced stage ovarian cancer. Materials and Methods: A three-cell (SKOV3, 3T3L1 and THP-1) co-culture model was established to mimic in vitro tumor microenvironment of ovarian cancer omental metastasis. Flow cytometry was performed for the adipocytes survival rate with Annexin V/PI double staining. Caspase-1 activity assay was used to detect the cleavage of substrate YVAD-AFC level in adipocytes and quantified by a fluorescence microliter plate reader. The free fatty acid assay kit was used to detect free fatty acid level in condition medium and ascites. Invasion assay and MTT assay were used to validate the invasive ability and cell viability of ovarian cancer cells. Immunohistochemistry was used to CD36 staining in clinical specimens, and correlation analysis through prism 8 software. Results: We observed the adipocyte pyroptosis in 3-cell co-culture model, and the free fatty acid increased in culture medium by flow cytometry analysis, caspase-1 activity assay kit and free fatty acid assay kit. In the meantime, the invasive ability and cisplatin resistance increased in ovarian cancer cells. The free fatty acid level in ascites positive correlated with CD36 expression (r2=0.2189, p=0.0375). Of note, combination treatment of cisplatin and sulfosuccinimidyl oleate (SSO) can reverse chemoresistance in 3-cell co-culture model. Overall, free fatty acid released form the pyroptotic adipocytes and increase invasive ability and chemoresistance in ovarian cancer cells. Block the interaction of free fatty acid and CD36 can reverse the chemoresistance in advanced ovarian cancer. Conclusion: In this study, we demonstrated adipocytes pyroptosis can increase the free fatty acid release to the microenvironment, and then promote ovarian cancer cell invasion and increase chemoresistance. For more important, inhibition of free fatty acid and CD36 interaction can reverse the chemoresistance in the in vitro experiments. Thus, reduce the adipocytes pyroptosis may be a novel therapeutic strategy for the omentum metastatic ovarian cancer. Citation Format: Chang-Ni Lin, Yu-Ling Liang, Keng-Fu Hsu, Yi-Ying Wu. Pyroptotic adipocytes contribute to chemoresistance in advanced stage ovarian cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5952.

Detection of CD36 gene polymorphism associated with chicken carcass traits and skin yellowness

Investigations into the association between chicken traits and genetic variations provide helpful breeding information to improve production performance and economic benefits in chickens. The single nucleotide polymorphism technique is an important method in agricultural molecular breeding. In this study, we detected 11 SNPs in the CD36 gene, 2 SNPs (g.-1974 A>G, g.-1888 T>C) located in the 5' flanking regions, 8 SNPs (g.23496 G>A, g.23643 C>T, g.23931 T>C, g.23937 G>A, g.31256 C>A, g.31258 C>T, g.31335 C>T, g.31534 A>C) located in the intron region, 1 SNPs (g.23743 G>T) located in the exon region and it belongs to synonymous mutation. In SNPs g.23743 G>T, the abdominal fat weight and abdominal fat weight rate of the GG genotype were lower than that of the TT genotype. In SNPs g.23931 T>C, the full-bore weight rate and half-bore weight rate of the TT genotype were higher compared with the CC genotype. And the SNPs g.-1888 T>C, g.23496 G>A, g.23643 C>T, g.31335 C>T and g.31534 A>C were significantly associated with skin yellowness traits, the cloacal skin yellowness before slaughter of the TT genotype was higher than that of the TC and CC genotype in SNPs g.-1888 T>C. Furthermore, 3 haplotypes of the above eleven SNPs were calculated and they correlated with heart weight, stomach weight, wing weight, leg skin yellowness and shin skin yellowness before slaughter. Finally, the CD36 expression profile displayed the expression pattern of CD36 mRNA variation in different tissues.

Exercise modifies fatty acid perception and metabolism.

Obesity is a major public health issue, which is associated with several chronic diseases. In rodents, voluntary wheel running (VWR) is a type of exercise that influences ingestive behavior. This study aims to investigate the possible function of VWR activity in the perception of fat taste and if it mitigates the immediate effects of fatty acid (FA) ingestion METHODS: Male C57BL/6 mice were arbitrarily assigned to either a sedentary (SED) lifestyle or free access to a running wheel after 5 weeks of dietary regimen. Later these mice groups were used in the investigations on fat preference, metabolic tolerance, and electrophysiology. Diet-induced alterations in CD36 and GPR120 expression that are related to fat perception and the capacitative calcium signaling caused by FA in taste bud cells (TBCs) were also examined. In obese groups, VWR temporarily reduced body weight, demonstrated improvement in preference scores for FA, and recovered from a deterioration in glucose homeostasis. In CD36-positive TBCs, electrophysiological investigations showed alterations in [Ca2+ ]i caused by FA. Further, in the TBCs of circumvallate papillae (CVP), there are differences in the expression of the genes CD36 and GPR120 between the active and SED controls. Obese mice also show lower incentive salience for long-chain fatty acids (LCFA) and adapted to the reward system of VWR which may lead to improved incentive salience accredited to wheel running CONCLUSION: In conclusion, this study provides the first evidence that VWR causes orosensory adaptations to fat and appears to alter taste preference for LCFAs.

High fat diet and PCSK9 knockout modulates lipid profile of the liver and changes the expression of lipid homeostasis related genes

BackgroundHigh fat diet (HFD) increases the likelihood of dyslipidemia, which can be a serious risk factor for atherosclerosis, diabetes or hepatosteatosis. Although changes in different blood lipid levels were broadly investigated, such alterations in the liver tissue have not been studied before. The aim of the current study was to investigate the effect of HFD on hepatic triglyceride (TG), diglyceride (DG) and ceramide (CER) levels and on the expression of four key genes involved in lipid homeostasis (Pcsk9, Ldlr, Cd36 and Anxa2) in the liver. In addition, the potential role of PCSK9 in the observed changes was further investigated by using PCSK9 deficient mice.MethodsWe used two in vivo models: mice kept on HFD for 20 weeks and PCSK9−/− mice. The amount of the major TGs, DGs and CERs was measured by using HPLC–MS/MS analysis. The expression profiles of four lipid related genes, namely Pcsk9, Ldlr, Cd36 and Anxa2 were assessed. Co-localization studies were performed by confocal microscopy.ResultsIn HFD mice, hepatic PCSK9 expression was decreased and ANXA2 expression was increased both on mRNA and protein levels, and the amount of LDLR and CD36 receptor proteins was increased. While LDLR protein level was also elevated in the livers of PCSK9−/− mice, there was no significant change in the expression of ANXA2 and CD36 in these animals. HFD induced a significant elevation in the hepatic levels of all measured TG and DG but not of CER types, and increased the proportion of monounsaturated vs. saturated TGs and DGs. Similar changes were detected in the hepatic lipid profiles of HFD and PCSK9−/− mice. Co-localization of PCSK9 with LDLR, CD36 and ANXA2 was verified in HepG2 cells.ConclusionsOur results show that obesogenic HFD downregulates PCSK9 expression in the liver and causes alterations in the hepatic lipid accumulation, which resemble those observed in PCSK9 deficiency. These findings suggest that PCSK9-mediated modulation of LDLR and CD36 expression might contribute to the HFD-induced changes in lipid homeostasis.

Palmitate-Induced Cardiac Lipotoxicity Is Relieved by the Redox-Active Motif of SELENOT through Improving Mitochondrial Function and Regulating Metabolic State.

Cardiac lipotoxicity is an important contributor to cardiovascular complications during obesity. Given the fundamental role of the endoplasmic reticulum (ER)-resident Selenoprotein T (SELENOT) for cardiomyocyte differentiation and protection and for the regulation of glucose metabolism, we took advantage of a small peptide (PSELT), derived from the SELENOT redox-active motif, to uncover the mechanisms through which PSELT could protect cardiomyocytes against lipotoxicity. To this aim, we modeled cardiac lipotoxicity by exposing H9c2 cardiomyocytes to palmitate (PA). The results showed that PSELT counteracted PA-induced cell death, lactate dehydrogenase release, and the accumulation of intracellular lipid droplets, while an inert form of the peptide (I-PSELT) lacking selenocysteine was not active against PA-induced cardiomyocyte death. Mechanistically, PSELT counteracted PA-induced cytosolic and mitochondrial oxidative stress and rescued SELENOT expression that was downregulated by PA through FAT/CD36 (cluster of differentiation 36/fatty acid translocase), the main transporter of fatty acids in the heart. Immunofluorescence analysis indicated that PSELT also relieved the PA-dependent increase in CD36 expression, while in SELENOT-deficient cardiomyocytes, PA exacerbated cell death, which was not mitigated by exogenous PSELT. On the other hand, PSELT improved mitochondrial respiration during PA treatment and regulated mitochondrial biogenesis and dynamics, preventing the PA-provoked decrease in PGC1-α and increase in DRP-1 and OPA-1. These findings were corroborated by transmission electron microscopy (TEM), revealing that PSELT improved the cardiomyocyte and mitochondrial ultrastructures and restored the ER network. Spectroscopic characterization indicated that PSELT significantly attenuated infrared spectral-related macromolecular changes (i.e., content of lipids, proteins, nucleic acids, and carbohydrates) and also prevented the decrease in membrane fluidity induced by PA. Our findings further delineate the biological significance of SELENOT in cardiomyocytes and indicate the potential of its mimetic PSELT as a protective agent for counteracting cardiac lipotoxicity.

The effect of maternal period nutritional status on oro-sensorial fat perception and taste preference in rats.

CD36 and GPR120 play an important role in the perception and preference for fat-rich food consumption. We aimed to investigate the relationship between oro-gustatory perception of lipids, fatty taste preference, and maternal (Gestation + Lactation)-maturation period nutrition status in offspring Sprague-Dawley rats. In our study, mother rats were fed with control (C) or high-fat diets (HFD) during gestation (21days) and lactation (21days) periods. After weaning, the offspring were fed with control (C) or high-fat diets (HFD) during the maturation (120days) period. Daily calorie intake and weekly body weight measurements were monitored. Two-bottle preference (TBPT) and licking tests measured the fat perceptions and preferences. Plasma levels of insulin, leptin, glucose, and triglyceride were measured. The protein and mRNA expressions of CD36 and GPR120 in the circumvallate papillae (CVP) were determined. The 48h TBPT results revealed that maternal HFD-exposed offspring rats significantly preferred 2% rapeseed oil solution regardless of the type of maturation diet. According to the licking test, C/C group (C diet exposed group in maternal and maturation periods) offspring licked 0.1% oleic acid-containing water more than C/HFD (C diet exposed in maternal period and HFD exposed group in maturation period) and HFD/HFD group. (HFD exposed group in maternal and maturation periods) groups. Plasma insulin and leptin concentrations significantly increased in HFD/HFD groups compared to C/C group. CD36 protein expressions were significantly lower in HFD/HFD than C/HFD and HFD/C groups. GPR120 and GNAT3 mRNA expressions in HFD/C group were significantly higher than in C/HFD group. Our results suggest that HFD exposure during maternal and maturation period may play a role in fat perception/preference through oral lipid sensors.

Effects of frog skin peptide temporin-1CEa and its analogs on ox-LDL induced macrophage-derived foam cells.

Purpose: Atherosclerosis is one of the most important pathological foundations of cardiovascular and cerebrovascular diseases with high morbidity and mortality. Studies have shown that macrophages play important roles in lipid accumulation in the vascular wall and thrombosis formation in atherosclerotic plaques. This study aimed to explore the effect of frog skin antimicrobial peptides (AMPs) temporin-1CEa and its analogs on ox-LDL induced macrophage-derived foam cells. Methods: CCK-8, ORO staining, and intracellular cholesterol measurements were used to study cellular activity, lipid droplet formation and cholesterol levels, respectively. ELISA, real-time quantitative PCR, Western blotting and flow cytometry analysis were used to study the expression of inflammatory factors, mRNA and proteins associated with ox-LDL uptake and cholesterol efflux in macrophage-derived foam cells, respectively. Furthermore, the effects of AMPs on inflammation signaling pathways were studied. Results: Frog skin AMPs could significantly increase the cell viability of the ox-LDL-induced foaming macrophages and decrease the formation of intracellular lipid droplets and the levels of total cholesterol and cholesterol ester (CE). Frog skin AMPs inhibited foaming formation by reducing the protein expression of CD36, which regulates ox-LDL uptake but had no effect on the expression of efflux proteins ATP binding cassette subfamily A/G member 1 (ABCA1/ABCG1). Then, decreased mRNA expression of NF-κB and protein expression of p-NF-κB p65, p-IκB, p-JNK, p-ERK, p-p38 and the release of TNF-α and IL-6 occurred after exposure to the three frog skin AMPs. Conclusion: Frog skin peptide temporin-1CEa and its analogs can improve the ox-LDL induced formation of macrophage-derived foam cells, in addition, inhibit inflammatory cytokine release through inhibiting the NF-κB and MAPK signaling pathways, thereby inhibiting inflammatory responses in atherosclerosis.

Adiponectin Enhances Fatty Acid Signaling in Human Taste Cells by Increasing Surface Expression of CD36.

Adiponectin, a key metabolic hormone, is secreted into the circulation by fat cells where it enhances insulin sensitivity and stimulates glucose and fatty acid metabolism. Adiponectin receptors are highly expressed in the taste system; however, their effects and mechanisms of action in the modulation of gustatory function remain unclear. We utilized an immortalized human fungiform taste cell line (HuFF) to investigate the effect of AdipoRon, an adiponectin receptor agonist, on fatty acid-induced calcium responses. We showed that the fat taste receptors (CD36 and GPR120) and taste signaling molecules (Gα-gust, PLCβ2, and TRPM5) were expressed in HuFF cells. Calcium imaging studies showed that linoleic acid induced a dose-dependent calcium response in HuFF cells, and it was significantly reduced by the antagonists of CD36, GPR120, PLCβ2, and TRPM5. AdipoRon administration enhanced HuFF cell responses to fatty acids but not to a mixture of sweet, bitter, and umami tastants. This enhancement was inhibited by an irreversible CD36 antagonist and by an AMPK inhibitor but was not affected by a GPR120 antagonist. AdipoRon increased the phosphorylation of AMPK and the translocation of CD36 to the cell surface, which was eliminated by blocking AMPK. These results indicate that AdipoRon acts to increase cell surface CD36 in HuFF cells to selectively enhance their responses to fatty acids. This, in turn, is consistent with the ability of adiponectin receptor activity to alter taste cues associated with dietary fat intake.