Role of FATP in parenchymal cell fatty acid uptake

Rice Protein Reduces Triglyceride Levels through Modulating CD36, MTP, FATP, and FABP Expression in Growing and Adult Rats

To elucidate the effect of rice protein on the regulation of triglyceride transport to reduce triglyceride levels, growing and adult male Wistar rats were fed with casein and rice protein for 2 weeks. With the intake of rice protein, the gene and protein expressions of cluster determinant 36 (CD36), microsomal triglyceride transfer protein (MTP), fatty acid transport protein-2 (FATP-2), and fatty acid-binding protein-1 (FABP-1) were, respectively, downregulated in growing and adult rats, suggesting rice protein could effectively regulate triglyceride transport. As a result, rice protein significantly reduced plasma levels of triglyceride and fatty acids, while hepatic accumulations of triglyceride and fatty acids were also decreased via rice protein. The present study demonstrates that RP exerts regulatory effects on CD36, MTP, FATP-2, and FABP-1 expression in growing and adult rats, revealing a link to triglyceride-lowering actions and the modulations of triglyceride transport exerted by rice protein. Results suggest that the aging process cannot attenuate the depression of CD36, MTP, FATP, and FABP 19 expression to reduce triglyceride levels induced by rice protein.

FATP2 activates PI3K/Akt/mTOR pathway by inhibiting ATF3 and promotes the occurrence and development of bladder cancer

Bladder cancer (BLCA) is ranked among the main causes of mortality in male cancer patients, and research into targeted therapies guided by its genomics and molecular biology has been a prominent focus in BLCA studies. Fatty acid transporter protein 2 (FATP2), a member of the FATPs family,is a key contributor to the progression of cancers such as hepatocellular carcinomas and melanomas.However,its role in BLCA remains poorly understand. This study delved into the function of FATP2 in BLCA through a succession of experiments in vivo and in vitro, employing techniques as quantitative real-time polymerase chain reaction (qRT-PCR), RNA sequencing, transwell assays, immunofluorescence, western blot,and others to dissect its mechanistic actions. The findings revealed that an oncogenic function is executed by FATP2 in bladder cancer, significantly impacting the proliferation and migration capabilities, thereby affecting the prognosis of BLCA patients. Furthermore, A suppression that relies on both time and concentration of BLCA proliferation and migration, trigger of apoptosis, and blockage of the cell cycle at the G2/M phase were observed when the inhibitor of FATP2, Lipofermata, was applied. It was unveiled through subsequent investigations that ATF3 expression is indirectly promoted by Lipofermata through the inhibition of FATP2, ultimately inhibiting the signal transduction of the PI3K/Akt/mTOR pathway. This effect was also responsible for the inhibitory impact on BLCA proliferation. Therefore, FATP2 emerges as an auspicious and emerging molecular target with potential applications in precision therapy in BLCA.

Updated mechanisms of MASLD pathogenesis

Metabolic dysfunction-associated steatotic liver disease (MASLD) has garnered considerable attention globally. Changing lifestyles, over-nutrition, and physical inactivity have promoted its development. MASLD is typically accompanied by obesity and is strongly linked to metabolic syndromes. Given that MASLD prevalence is on the rise, there is an urgent need to elucidate its pathogenesis. Hepatic lipid accumulation generally triggers lipotoxicity and induces MASLD or progress to metabolic dysfunction-associated steatohepatitis (MASH) by mediating endoplasmic reticulum stress, oxidative stress, organelle dysfunction, and ferroptosis. Recently, significant attention has been directed towards exploring the role of gut microbial dysbiosis in the development of MASLD, offering a novel therapeutic target for MASLD. Considering that there are no recognized pharmacological therapies due to the diversity of mechanisms involved in MASLD and the difficulty associated with undertaking clinical trials, potential targets in MASLD remain elusive. Thus, this article aimed to summarize and evaluate the prominent roles of lipotoxicity, ferroptosis, and gut microbes in the development of MASLD and the mechanisms underlying their effects. Furthermore, existing advances and challenges in the treatment of MASLD were outlined.

Glia-derived secretory fatty acid binding protein Obp44a regulates lipid storage and efflux in the developing Drosophila brain

Glia derived secretory factors play diverse roles in supporting the development, physiology, and stress responses of the central nervous system (CNS). Through transcriptomics and imaging analyses, we have identified Obp44a as one of the most abundantly produced secretory proteins from Drosophila CNS glia. Protein structure homology modeling and Nuclear Magnetic Resonance (NMR) experiments reveal Obp44a as a fatty acid binding protein (FABP) with a high affinity towards long-chain fatty acids in both native and oxidized forms. Further analyses demonstrate that Obp44a effectively infiltrates the neuropil, traffics between neuron and glia, and is secreted into hemolymph, acting as a lipid chaperone and scavenger to regulate lipid and redox homeostasis in the developing brain. In agreement with this essential role, deficiency of Obp44a leads to anatomical and behavioral deficits in adult animals and elevated oxidized lipid levels. Collectively, our findings unveil the crucial involvement of a noncanonical lipid chaperone to shuttle fatty acids within and outside the brain, as needed to maintain a healthy brain lipid environment. These findings could inspire the design of novel approaches to restore lipid homeostasis that is dysregulated in CNS diseases.

Transcriptome analysis of norepinephrine-induced lipolysis in differentiated adipocytes of Bama pig

Sympathetic innervation of white adipose tissue (WAT) plays a key role in the regulation of lipid metabolism. Sympathetic activation promotes release of norepinephrine (NE), which binds to adrenergic receptors on adipocytes, promoting adipocyte lipolysis and enhanced oxidative metabolism. However, the mechanism by which sympathetic nerves regulate lipid metabolism in pig adipose tissue remains unclear. We used NE to simulate the process of sympathetic driving in pig adipocytes. RNA sequencing (RNA-seq) was used to determine the gene expression profile of pig adipocytes responding to NE stimulation. Our data suggests that the lipolytic signaling pathway is activated in pig adipocytes upon acute stimulation of NE, resulting in enhanced lipid metabolism and lipolysis, consistent with the phenomena found in humans and mice. Specifically, differentially expressed protein coding genes (PCGs) (SIRT4, SLC27A1) are mainly associated with functions that inhibit fatty acid oxidation and promote lipid synthesis. Similarly, we investigated the changes in regulatory transcripts such as long non-coding RNAs (lncRNAs) and transcripts of uncertain coding potential (TUCP) in response to NE and found that differentially expressed lncRNAs (lncG47338, lncG30660, lncG29516, lncG3790) and TUCP (TUCP_G38001) were co-expressed with target genes related to the promotion of fatty acid β-oxidation, lipolysis and oxidative metabolism, thus acting as regulators. These results indicate a broad suite of gene expression alterations in response to NE stimulation and promote the understanding of the molecular mechanisms by which NE regulates lipid metabolism in pigs.

Alcohol, White Adipose Tissue, and Brown Adipose Tissue: Mechanistic Links to Lipogenesis and Lipolysis

According to data from the World Health Organization, there were about 3 million deaths caused by alcohol consumption worldwide in 2016, of which about 50% were related to liver disease. Alcohol consumption interfering with the normal function of adipocytes has an important impact on the pathogenesis of alcoholic liver disease. There has been increasing recognition of the crucial role of adipose tissue in regulating systemic metabolism, far beyond that of an inert energy storage organ in recent years. The endocrine function of adipose tissue is widely recognized, and the significance of the proteins it produces and releases is still being investigated. Alcohol consumption may affect white adipose tissue (WAT) and brown adipose tissue (BAT), which interact with surrounding tissues such as the liver and intestines. This review briefly introduces the basic concept and classification of adipose tissue and summarizes the mechanism of alcohol affecting lipolysis and lipogenesis in WAT and BAT. The adipose tissue-liver axis is crucial in maintaining lipid homeostasis within the body. Therefore, this review also demonstrates the effects of alcohol consumption on the adipose tissue-liver axis to explore the role of alcohol consumption in the crosstalk between adipose tissue and the liver.

Metabolic dependencies and targets in ovarian cancer

Reprogramming of cellular metabolism is a hallmark of cancer. Cancer cells undergo metabolic adaptations to maintain tumorigenicity and survive under the attack of immune cells and chemotherapy in the tumor microenvironment. Metabolic alterations in ovarian cancer in part overlap with findings from other solid tumors and in part reflect unique traits. Altered metabolic pathways not only facilitate ovarian cancer cells' survival and proliferation but also endow them to metastasize, acquire resistance to chemotherapy, maintain cancer stem cell phenotype and escape the effects of anti-tumor immune defense. In this review, we comprehensively review the metabolic signatures of ovarian cancer and their impact on cancer initiation, progression, and resistance to treatment. We highlight novel therapeutic strategies targeting metabolic pathways under development.

Analyses of regulatory network and discovery of potential biomarkers for Korean rockfish (Sebastes schlegelii) in responses to starvation stress through transcriptome and metabolome

Whether in aquaculture or in nature, starvation stress limits the growth of fish. The purpose of the study was to clarify the detailed molecular mechanisms underlying starvation stress in Korean rockfish (Sebastes schlegelii) through liver transcriptome and metabolome analysis. Transcriptome results showed that liver genes associated with cell cycle and fatty acid synthesis were down-regulated, whereas those related to fatty acid decomposition were up-regulated in the experimental group (EG; starved for 72 days) compared to the control group (CG; feeding). Metabolomic results showed that there were significant differences in the levels of metabolites related to nucleotide metabolism and energy metabolism, such as purine metabolism, histidine metabolism and oxidative phosphorylation. Five fatty acids (C22:6n-3; C22:5n-3; C20:5n-3; C20:4n-3; C18:3n-6) were selected as possible biomarkers of starvation stress from the differential metabolites of metabolome. Subsequently, correlation between these differential genes of lipid metabolism and cell cycle and differential metabolites were analyzed, and observed that these five fatty acids were significantly correlated with the differential genes. These results provide new clues for understanding the role of fatty acid metabolism and cell cycle in fish under starvation stress. It also provides a reference for promoting the biomarker identification of starvation stress and stress tolerance breeding research.

SLC27A5 promotes sorafenib-induced ferroptosis in hepatocellular carcinoma by downregulating glutathione reductase

Sorafenib, a first-line drug for advanced hepatocellular carcinoma (HCC), shows a favorable anti-tumor effect while resistance is a barrier impeding patients from benefiting from it. Thus, more efforts are needed to lift this restriction. Herein, we first find that solute carrier family 27 member 5 (SLC27A5/FATP5), an enzyme involved in the metabolism of fatty acid and bile acid, is downregulated in sorafenib-resistant HCC. SLC27A5 deficiency facilitates the resistance towards sorafenib in HCC cells, which is mediated by suppressing ferroptosis. Further mechanism studies reveal that the loss of SLC27A5 enhances the glutathione reductase (GSR) expression in a nuclear factor erythroid 2-related factor 2 (NRF2)-dependent manner, which maintains glutathione (GSH) homeostasis and renders insensitive to sorafenib-induced ferroptosis. Notably, SLC27A5 negatively correlates with GSR, and genetic or pharmacological inhibition of GSR strengthens the efficacy of sorafenib through GSH depletion and the accumulation of lipid peroxide products in SLC27A5-knockout and sorafenib-resistant HCC cells. Based on our results, the combination of sorafenib and carmustine (BCNU), a selective inhibitor of GSR, remarkably hamper tumor growth by enhancing ferroptotic cell death in vivo. In conclusion, we describe that SLC27A5 serves as a suppressor in sorafenib resistance and promotes sorafenib-triggered ferroptosis via restraining the NRF2/GSR pathway in HCC, providing a potential therapeutic strategy for overcoming sorafenib resistance.

Fatty acid transport proteins (FATPs) in cancer

Lipids play pivotal roles in cancer biology. Lipids have a wide range of biological roles, especially in cell membrane synthesis, serve as energetic molecules in regulating energy-demanding processes; and they play a significant role as signalling molecules and modulators of numerous cellular functions. Lipids may participate in the development of cancer through the fatty acid signalling pathway. Lipids consumed in the diet act as a key source of extracellular pools of fatty acids transported into the cellular system. Increased availability of lipids to cancer cells is due to increased uptake of fatty acids from adipose tissues. Lipids serve as a source of energy for rapidly dividing cancerous cells. Surviving requires the swift synthesis of biomass and membrane matrix to perform exclusive functions such as cell proliferation, growth, invasion, and angiogenesis. FATPs (fatty acid transport proteins) are a group of proteins involved in fatty acid uptake, mainly localized within cells and the cellular membrane, and have a key role in long-chain fatty acid transport. FATPs are composed of six isoforms that are tissue-specific and encoded by a specific gene. Previous studies have reported that FATPs can alter fatty acid metabolism, cell growth, and cell proliferation and are involved in the development of various cancers. They have shown increased expression in most cancers, such as melanoma, breast cancer, prostate cancer, renal cell carcinoma, hepatocellular carcinoma, bladder cancer, and lung cancer. This review introduces a variety of FATP isoforms and summarises their functions and their possible roles in the development of cancer.

Improvement of obesity-induced fatty liver disease by intermittent hypoxia exposure in a murine model

Background: The high prevalence of non-alcoholic fatty liver disease (NAFLD) in the world raises an important concern for human health. The western diet containing high fat and fructose is the risk factor for NAFLD development. Intermittent hypoxia (IH), known as the basis of obstructive sleep apnea (OSA), normally is correlated with impaired liver function. However, the role of IH in liver injury prevention has been revealed by many other studies based on the different IH paradigms. The current study, therefore, tests the impact of IH on the liver of high-fat and high-fructose diet (HFHFD) fed mice. Material and Method: Mice were exposed to IH (2 min cycle, FiO₂ 8% for 20 s, FiO₂ 20.9% for 100 s; 12 h/day) or intermittent air (FiO₂ 20.9%) for 15 weeks, with normal diet (ND) or high-fat and high-fructose diet (HFHFD). Indices of liver injury and metabolism were measured. Results: IH causes no overt liver injury in mice fed an ND. However, HFHFD-induced lipid accumulation, lipid peroxidation, neutrophil infiltration, and apoptotic process were significantly attenuated by IH exposure. Importantly, IH exposure altered bile acids composition and shifted the hepatic bile acids towards FXR agonism, which was involved in the protection of IH against HFHFD. Conclusion: These results support that the IH pattern in our model prevents liver injury from HFHFD in experimental NAFLD.

A novel therapy for hepatic cholestasis treatment-the combination of rosiglitazone and fenofibrate

Hepatic cholestasis can develop into liver fibrosis and eventually liver failure. Currently, ursodeoxycholic acid (UDCA) or UDCA combined with fenofibrate is used for cholestasis treatment. Rosiglitazone inhibited α-naphthyl isothiocyanate (ANIT)-induced cholestasis in mice. In this study, we compared the effect of rosiglitazone, UDCA, fenofibrate, combined rosiglitazone and fenofibrate or UDCA and fenofibrate on ANIT-induced cholestasis. C57BL/6J mice were induced cholestasis by ANIT while treated with rosiglitazone, UDCA, fenofibrate, combination of rosiglitazone and fenofibrate, or combination of UDCA and fenofibrate. Liver and serum samples were collected to determine liver necrosis and serum biochemical parameters. Rosiglitazone alone or combined with fenofibrate demonstrated better effects than UDCA alone or UDCA combined with fenofibrate in reduction of cholestasis-induced serum biochemical parameters and liver necrosis. Surprisingly, UDCA combined with fenofibrate, but not rosiglitazone combined with fenofibrate, potently increased accumulation of free fatty acids (FFAs) in the liver. Mechanistically, the protection of combination of rosiglitazone and fenofibrate against cholestasis was attributed to activated adiponectin pathway to enhance FXR and mitochondrial functions and reduce apoptosis in the liver. The accumulation of FFAs in the liver by combination of UDCA and fenofibrate was caused by activation of fatty acid biosynthesis and uptake, and triglyceride hydrolysis. Taken together, our study not only demonstrates the adverse effect of combination therapy of UDCA and fenofibrate, but also suggests the combination of rosiglitazone and fenofibrate can be another option for cholestasis treatment.

Endothelial Lipid Metabolism

Endothelial cells (ECs) line all vessels of all vertebrates and are fundamental to organismal metabolism. ECs rely on their metabolism both to transport nutrients in and out of underlying parenchyma, and to support their own cellular activities, including angiogenesis. ECs primarily consume glucose, and much is known of how ECs transport and consume glucose and other carbohydrates. In contrast, how lipids are transported, and the role of lipids in normal EC function, has garnered less attention. We review here recent developments on the role of lipids in endothelial metabolism, with a focus on lipid uptake and transport in quiescent endothelium, and the use of lipid pathways during angiogenesis.

FATP1 Exerts Variable Effects on Adipogenic Differentiation and Proliferation in Cells Derived From Muscle and Adipose Tissue

In livestock, intramuscular adipose tissue is highly valued whereas adipose tissue in other depots is considered as waste. Thus, genetic factors that favor fat deposition in intramuscular compartments over that in other adipose depots are highly desirable in meat-producing animals. Fatty acid transport 1 (FATP1) has been demonstrated to promote cellular fatty acid uptake and metabolism; however, whether it also influences cellular lipid accumulation remains unclear. In the present study, we investigated the effects of FATP1 on the differentiation and proliferation of adipocytes in five types of cells derived from muscle and adipose tissue and estimated the effects of FATP1 on intramuscular fat (IMF) deposition. We showed that FATP1 is mainly expressed in heart and muscle tissue in buffaloes as well as cells undergoing adipogenic differentiation. Importantly, we found that FATP1 promoted the adipogenic differentiation of muscle-derived cells (buffalo myocytes and intramuscular preadipocytes and mouse C2C12 cells) but did not affect, or even inhibited, that of adipose-derived cells (buffalo subcutaneous preadipocytes and mouse 3T3-L1 cells, respectively). Correspondingly, our results further indicated that FATP1 promotes IMF deposition in mice in vivo. Meanwhile, FATP1 was found to enhance the proliferative activity of all the assessed cells, except murine 3T3-L1 cells. These results provide new insights into the potential effects of FATP1 on IMF deposition, especially regarding its positive effects on meat quality in buffaloes and other livestock.

Downregulation of SLC27A6 by DNA Hypermethylation Promotes Proliferation but Suppresses Metastasis of Nasopharyngeal Carcinoma Through Modulating Lipid Metabolism

Lipid is the building block and an important source of energy, contributing to the malignant behavior of tumor cells. Recent studies suggested that lipid droplets (LDs) accumulations were associated with nasopharyngeal carcinoma (NPC) progression. Solute carrier family 27 member 6 (SLC27A6) mediates the cellular uptake of long-chain fatty acid (LCFA), a necessary lipid component. However, the functions of SLC27A6 in NPC remain unknown. Here, we found a significant reduction of SLC27A6 mRNA in NPC tissues compared with normal nasopharyngeal epithelia (NNE). The promoter methylation ratio of SLC27A6 was greater in NPC than in non-cancerous tissues. The demethylation reagent 5-aza-2'-deoxycytidine (5-aza-dC) remarkably restored the mRNA expression of SLC27A6, suggesting that this gene was downregulated in NPC owing to DNA promoter hypermethylation. Furthermore, SLC27A6 overexpression level in NPC cell lines led to significant suppression of cell proliferation, clonogenicity in vitro, and tumorigenesis in vivo. Higher SLC27A6 expression, on the other hand, promoted NPC cell migration and invasion. In particular, re-expression of SLC27A6 faciliated epithelial-mesenchymal transition (EMT) signals in xenograft tumors. Furthermore, we observed that SLC27A6 enhanced the intracellular amount of triglyceride (TG) and total cholesterol (T-CHO) in NPC cells, contributing to lipid biosynthesis and increasing metastatic potential. Notably, the mRNA level of SLC27A6 was positively correlated with cancer stem cell (CSC) markers, CD24 and CD44. In summary, DNA promoter hypermethylation downregulated the expression of SLC27A6. Furthermore, re-expression of SLC27A6 inhibited the growth capacity of NPC cells but strengthened the CSC markers. Our findings revealed the dual role of SLC27A6 in NPC and shed novel light on the link between lipid metabolism and CSC maintenance.

Fatty acid metabolism and acyl-CoA synthetases in the liver-gut axis

Fatty acids are energy substrates and cell components which participate in regulating signal transduction, transcription factor activity and secretion of bioactive lipid mediators. The acyl-CoA synthetases (ACSs) family containing 26 family members exhibits tissue-specific distribution, distinct fatty acid substrate preferences and diverse biological functions. Increasing evidence indicates that dysregulation of fatty acid metabolism in the liver-gut axis, designated as the bidirectional relationship between the gut, microbiome and liver, is closely associated with a range of human diseases including metabolic disorders, inflammatory disease and carcinoma in the gastrointestinal tract and liver. In this review, we depict the role of ACSs in fatty acid metabolism, possible molecular mechanisms through which they exert functions, and their involvement in hepatocellular and colorectal carcinoma, with particular attention paid to long-chain fatty acids and small-chain fatty acids. Additionally, the liver-gut communication and the liver and gut intersection with the microbiome as well as diseases related to microbiota imbalance in the liver-gut axis are addressed. Moreover, the development of potentially therapeutic small molecules, proteins and compounds targeting ACSs in cancer treatment is summarized.

Dietary Nano-ZnO Is Absorbed via Endocytosis and ZIP Pathways, Upregulates Lipogenesis, and Induces Lipotoxicity in the Intestine of Yellow Catfish

Nano-sized zinc oxide (nano-ZnO) affects lipid deposition, but its absorption patterns and mechanisms affecting lipid metabolism are still unclear. This study was undertaken to investigate the molecular mechanism of nano-ZnO absorption and its effects on lipid metabolism in the intestinal tissues of a widely distributed freshwater teleost yellow catfish Pelteobagrus fulvidraco. We found that 100 mg/kg dietary nano-ZnO (H-Zn group) significantly increased intestinal Zn contents. The zip6 and zip10 mRNA expression levels were higher in the H-Zn group than those in the control (0 mg/kg nano-ZnO), and zip4 mRNA abundances were higher in the control than those in the L-Zn (50 mg/kg nano-ZnO) and H-Zn groups. Eps15, dynamin1, dynamin2, caveolin1, and caveolin2 mRNA expression levels tended to reduce with dietary nano-ZnO addition. Dietary nano-ZnO increased triglyceride (TG) content and the activities of the lipogenic enzymes glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and isocitrate dehydrogenase (ICDH), upregulated the mRNA abundances of lipogenic genes 6pgd, fatty acid synthase (fas), and sterol regulatory element binding protein 1 (srebp1), and reduced the mRNA expression of farnesoid X receptor (fxr) and small heterodimer partner (shp). The SHP protein level in the H-Zn group was lower than that in the control and the L-Zn group markedly. Our in vitro study indicated that the intestinal epithelial cells (IECs) absorbed nano-ZnO via endocytosis, and nano-Zn-induced TG deposition and lipogenesis were partially attributable to the endocytosis of nano-ZnO in IECs. Mechanistically, nano-ZnO-induced TG deposition was closely related to the metal responsive transcription factor 1 (MTF-1)-SHP pathway. Thus, for the first time, we found that the lipogenesis effects of nano-ZnO probably depended on the key gene shp, which is potentially regulated by MTF1 and/or FXR. This novel signaling pathway of MTF-1 through SHP may be relevant to explain the toxic effects and lipotoxicity ascribed to dietary nano-ZnO addition.

The role of FATP1 in lipid accumulation: a review

Lipid accumulation in mammals has been widely studied for decades due to its significant association with obesity in humans and meat quality in livestock animals. Fatty acid transport 1 (FATP1) is an evolutionarily conserved protein that localizes to the plasma membrane to enhance the transportation of fatty acids (FAs). In line with this function, FATP1 is involved in the metabolism of FAs, including their esterification and oxidation. In addition, the expression of FATP1 can be regulated by several energy-related factors, such as insulin and PPAR activators and transcription factors. These events connect FATP1 with cellular lipid accumulation. Recently, several studies have suggested that FATP1 acts as a facilitator in cellular lipid accumulation, whereas others hold a contrary view. Here, we will review these data and probe the possibility that FATP1 acts as a regulator in lipid accumulation, which will provide effective information for studies on the relationship between FATP1 and obesity in humans and meat quality in livestock animals.

Local Mitochondrial ATP Production Regulates Endothelial Fatty Acid Uptake and Transport

Most organs use fatty acids (FAs) as a key nutrient, but little is known of how blood-borne FAs traverse the endothelium to reach underlying tissues. We conducted a small-molecule screen and identified niclosamide as a suppressor of endothelial FA uptake and transport. Structure/activity relationship studies demonstrated that niclosamide acts through mitochondrial uncoupling. Inhibitors of oxidative phosphorylation and the ATP/ADP translocase also suppressed FA uptake, pointing principally to ATP production. Decreasing total cellular ATP by blocking glycolysis did not decrease uptake, indicating that specifically mitochondrial ATP is required. Endothelial FA uptake is promoted by fatty acid transport protein 4 (FATP4) via its ATP-dependent acyl-CoA synthetase activity. Confocal microscopy revealed that FATP4 resides in the endoplasmic reticulum (ER), and that endothelial ER is intimately juxtaposed with mitochondria. Together, these data indicate that mitochondrial ATP production, but not total ATP levels, drives endothelial FA uptake and transport via acyl-CoA formation in mitochondrial/ER microdomains.

Effects of copper hydroxychloride on growth performance and abundance of genes involved in lipid metabolism of growing pigs

An experiment was conducted to test the hypothesis that copper (Cu) hydroxychloride improves growth performance by upregulating the mRNA transcription of genes involved in lipid metabolism of pigs fed a diet based on corn, soybean meal (SBM), and distillers dried grains with solubles (DDGS). Thirty-two pigs (15.05 ± 0.98 kg) were allotted to 2 dietary treatments with 2 pigs per pen for a total of 8 replicate pens per treatment. Pigs were fed a corn-SBM-DDGS control diet that included Cu to meet the requirement. A second diet was formulated by adding 150 mg Cu/kg from copper hydroxychloride to the control diet. On the last day of the experiment, one pig per pen was sacrificed, and samples from liver, skeletal muscle, and subcutaneous adipose tissue were collected to analyze relative mRNA abundance of genes involved in lipid metabolism. Results indicated that overall ADG and G:F were greater (P < 0.05) for pigs fed the diet containing copper hydroxychloride compared with pigs fed the control diet. Pigs fed the diet supplemented with copper hydroxychloride also had increased (P < 0.05) abundance of cluster of differentiation 36 in the liver and increased (P < 0.05) abundance of fatty acid-binding protein 4 and lipoprotein lipase in subcutaneous adipose tissue. Inclusion of copper hydroxychloride also tended to increase (P < 0.10) the abundance of fatty acid-binding protein 1, peroxisome proliferator-activated receptor α, and carnitine palmitoyltransferase 1B in the liver, skeletal muscle, and subcutaneous adipose tissue, respectively. This indicates that dietary Cu may affect signaling pathways associated with lipid metabolism by improving the uptake, transport, and utilization of fatty acids. In conclusion, supplementation of copper hydroxychloride to the control diet improved growth performance and upregulated the abundance of some genes involved in postabsorptive metabolism of lipids.

Ovarian Cancer-Why Lipids Matter

This review highlights recent advances in the understanding of the relevance of altered lipid metabolic pathways contributing to the poor prognosis of high grade serous ovarian cancer, as they relate to cancer metastasis and cancer stemness. Increased lipid uptake regulated by the receptor CD36 and the transport protein FABP4 has been implicated in ovarian cancer metastasis. The symbiotic relationship between ovarian cancer cells and adipocytes was shown to be important for sustaining widespread peritoneal and omental metastasis. Increased lipogenesis dependent on the fatty acid desaturase SCD1 was detected in ovarian cancer stem cells. Furthermore, response to therapy, specifically to platinum, was linked to increased fatty acid biogenesis, while the survival of drug tolerant cells was shown to depend on lipid peroxidation. These recent findings suggest that lipids are necessary elements supporting oncogenic signaling and the energetic needs of rapidly proliferating cancer cells. New strategies targeting key enzymes involved in lipid uptake or utilization in cancer cells have been shown to exert anti-tumor effects and are being developed as cancer interventions in combination with chemotherapy or immunotherapy.

Expression of lipid metabolism genes provides new insights into intramuscular fat deposition in Laiwu pigs

Objective

The objective of this study was to measure the special expression pattern of lipid metabolism genes and investigate the molecular mechanisms underlying intramuscular fat (IMF) deposition in Longissimus dorsi muscle of Laiwu pigs.

Methods

Thirty-six pigs (Laiwu n = 18; Duroc×Landrace×Yorkshire n = 18) were used for the measurement of the backfat thickness, marbling score, IMF content, and expression of lipid metabolism genes.

Results

Significant correlations were found between IMF content and the mRNA expression of lipid metabolism genes. Of the 14 fat deposition genes measured, fatty acid synthase (FASN) showed the strongest correlation (r = 0.75, p = 0.001) with IMF content, and of the 6 fat removal genes, carnitine palmitoyl transferase 1B (CPT1B) exhibited the greatest negative correlation (r = −0.66, p = 0.003) with IMF content in Laiwu pig. Multiple regression analysis showed that CPT1B, FASN, solute carrier family 27 member 1 (SLC27A1), and fatty acid binding protein 3 (FABP3) contributed 38% of the prediction value for IMF content in Laiwu pigs. Of these four variables, CPT1B had the greatest contribution to IMF content (14%) followed by FASN (11%), SLC27A1 (9%), and FABP3 (4%).

Conclusion

Our results indicate that the combined effects of an upregulation in fat deposition genes and downregulation in fat removal genes promotes IMF deposition in Laiwu pigs.

Expression of APOB, ADFP and FATP1 and their correlation with fat deposition in Yunnan's top six famous chicken breeds

1. Adipose differentiation related protein (ADFP), fatty acid transport protein 1 (FATP1) and apolipoprotein B (APOB) are suspected to play an important role in determining intramuscular fat and in overall meat quality. 2. Yunnan's top six famous chicken breeds (the Daweishan Mini, Yanjin Black-bone, Chahua, Wuding, Wuliangshan Black-bone and Piao chicken) are known for the high quality of their meat, but little is known about their expression of these three genes. 3. The present study aimed to examine the ADFP, FATP1 and APOB genes in different tissues of these six breeds at different development stages. The subcutaneous fat from the back midline and front, abdominal fat, liver and muscle tissue was sampled at 28, 49, 70, 91 and 112 days. The expression of ADFP, FATP1 and APOB was measured by real-time PCR. 4. The results showed that the expression of the three genes differed depending on age, tissue types and breeds. However, the expression of the three genes correlated with fat traits. In conclusion, the expression of the ADFP, FATP1 and APOB genes is associated with the fat traits of Yunnan's top six chicken breeds. These results could help with molecular marker screening and marker-assisted breeding to improve the quality of poultry for meat production.

Altered gene expression and metabolism in fetal umbilical cord mesenchymal stem cells correspond with differences in 5-month-old infant adiposity gain

The intrauterine period is a critical time wherein developmental exposure can influence risk for chronic disease including childhood obesity. Using umbilical cord-derived mesenchymal stem cells (uMSC) from offspring born to normal-weight and obese mothers, we tested the hypothesis that changes in infant body composition over the first 5 months of life correspond with differences in cellular metabolism and transcriptomic profiles at birth. Higher long-chain acylcarnitine concentrations, lipid transport gene expression, and indicators of oxidative stress in uMSC-adipocytes were related to higher adiposity at 5 months of age. In uMSC-myocytes, lower amino acid concentrations and global differential gene expression for myocyte growth, amino acid biosynthesis, and oxidative stress were related to lower infant percent fat-free mass at 5 months of age, particularly in offspring of obese mothers. This is the first evidence of human infant adipocyte- or myocyte-related alterations in cellular metabolic pathways that correspond with increased adiposity and lower fat-free mass in early infancy. These pathways might reflect the effects of an adverse maternal metabolic environment on the fetal metabolome and genome. Our findings suggest that programmed differences in infant stem cell metabolism correspond with differences in body composition in early life, a known contributor to obesity risk.

Picroside II attenuates fatty acid accumulation in HepG2 cells via modulation of fatty acid uptake and synthesis

Background/Aims

Hepatic steatosis is caused by an imbalance between free fatty acids (FFAs) uptake, utilization, storage, and disposal. Understanding the molecular mechanisms involved in FFAs accumulation and its modulation could drive the development of potential therapies for Nonalcoholic fatty liver disease. The aim of the current study was to explore the effects of picroside II, a phytoactive found in Picrorhiza kurroa, on fatty acid accumulation vis-à-vis silibinin, a known hepatoprotective phytoactive from Silybum marianum.

Methods

HepG2 cells were loaded with FFAs (oleic acid:palmitic acid/2:1) for 20 hours to mimic hepatic steatosis. The FFAs concentration achieving maximum fat accumulation and minimal cytotoxicity (500 μM) was standardized. HepG2 cells were exposed to the standardized FFAs concentration with and without picroside II pretreatment.

Results

Picroside II pretreatment inhibited FFAs-induced lipid accumulation by attenuating the expression of fatty acid transport protein 5, sterol regulatory element binding protein 1 and stearoyl CoA desaturase. Preatreatment with picroside II was also found to decrease the expression of forkhead box protein O1 and phosphoenolpyruvate carboxykinase.

Conclusions

These findings suggest that picroside II effectively attenuated fatty acid accumulation by decreasing FFAs uptake and lipogenesis. Picroside II also decreased the expression of gluconeogenic genes.

Effects of fatty acid transport protein 1 on proliferation and differentiation of porcine intramuscular preadipocytes

Fatty acid transport protein 1 (FATP1) plays an important role in the fatty acid transmembrane transport and fat deposition. However, its role in porcine intramuscular preadipocytes proliferation and differentiation remain poorly understood. Here, we examined the effects of pFATP1 on porcine intramuscular preadipocytes proliferation and differentiation. Overexpression of pFATP1 in porcine intramuscular preadipocytes significantly promoted the proliferation of porcine intramuscular preadipocytes, and also significantly upregulated the expressions of peroxisome proliferator-activated receptor γ, CCAAT enhancer binding protein α, lipoprotein lipase, fatty acid synthetase and perilipin 1. Moreover, overexpression of pFATP1 in porcine intramuscular preadipocytes significantly increased fat accumulation and downregulated β-catenin protein expression. Overall, our results indicated that pFATP1 played an important role in porcine intramuscular preadipocytes proliferation and differentiation, and it might promote adipogenesis in porcine intramuscular preadipocytes by repressing Wnt/β-catenin signaling pathway.

Effects of waterborne Cu exposure on intestinal copper transport and lipid metabolism of Synechogobius hasta

The present study was conducted to explore the effects of waterborne Cu exposure on intestinal Cu transport and lipid metabolism of Synechogobius hasta. S. hasta were exposed to 0, 0.4721 and 0.9442μM Cu, respectively. Sampling occurred on days 0, 21 and 42, respectively. Growth performance, intestinal lipid deposition, Cu content, and activities and mRNA expression of enzymes and genes involved in Cu transport and lipid metabolism were analyzed. Cu exposure decreased WG and SGR on days 21 and 42. Cu exposure increased intestinal Cu and lipid contents. Increased Cu accumulation was attributable to increased enzymatic activities (Cu-ATPase and Cu, Zn-SOD) and genes' (CTR1, CTR2, DMT1, ATP7a, ATP7b, MT1 and MT2) expression involved in Cu transport. Waterborne Cu exposure also increased activities of lipogenic enzymes (6PGD and ICDH on both days 21 and 42, ME on day 42), up-regulated mRNA levels of lipogenic genes (G6PD, 6PGD, ME, ICDH, FAS and ACCa), lipolytic genes (ACCb, CPT I and HSLa) and genes involved in intestinal fatty acid uptake (IFABP and FATP4) on both days 21 and 42. The up-regulation of lipolysis may result from the increased metabolic expenditure for detoxification and maintenance of the normal body functions in a response to Cu exposure. Meantime, Cu exposure increased lipogenesis and fatty acid uptake, leading to net lipid accumulation in the intestine despite increased lipolysis. To our knowledge, this is the first report involved in intestinal lipid metabolism in combination with intestinal Cu absorption following waterborne Cu exposure, which provides new insights and evidence into Cu toxicity in fish.

Obesity and cancer progression: is there a role of fatty acid metabolism?

Currently, there is renewed interest in elucidating the metabolic characteristics of cancer and how these characteristics may be exploited as therapeutic targets. Much attention has centered on glucose, glutamine and de novo lipogenesis, yet the metabolism of fatty acids that arise from extracellular, as well as intracellular, stores as triacylglycerol has received much less attention. This review focuses on the key pathways of fatty acid metabolism, including uptake, esterification, lipolysis, and mitochondrial oxidation, and how the regulators of these pathways are altered in cancer. Additionally, we discuss the potential link that fatty acid metabolism may serve between obesity and changes in cancer progression.

Deranged fatty acid composition causes pulmonary fibrosis in Elovl6-deficient mice

Despite the established role of alveolar type II epithelial cells for the maintenance of pulmonary function, little is known about the deregulation of lipid composition in the pathogenesis of pulmonary fibrosis. The elongation of long-chain fatty acids family member 6 (Elovl6) is a rate-limiting enzyme catalysing the elongation of saturated and monounsaturated fatty acids. Here we show that Elovl6 expression is significantly downregulated after an intratracheal instillation of bleomycin (BLM) and in human lung with idiopathic pulmonary fibrosis. Elovl6-deficient (Elovl6⁻/⁻) mice treated with BLM exhibit severe fibroproliferative response and derangement of fatty acid profile compared with wild-type mice. Furthermore, Elovl6 knockdown induces a change in fatty acid composition similar to that in Elovl6⁻/⁻ mice, resulting in induction of apoptosis, TGF-β1 expression and reactive oxygen species generation. Our findings demonstrate a previously unappreciated role for Elovl6 in the regulation of lung homeostasis, and in pathogenesis and exacerbation of BLM-induced pulmonary fibrosis.

Endothelial fatty acid transport: role of vascular endothelial growth factor B

Dietary lipids present in the circulation have to be transported through the vascular endothelium to be utilized by tissue cells, a vital mechanism that is still poorly understood. Vascular endothelial growth factor B (VEGF-B) regulates this process by controlling the expression of endothelial fatty acid transporter proteins (FATPs). Here, we summarize research on the role of the vascular endothelium in nutrient transport, with emphasis on VEGF-B signaling.

Effect of chronic intermittent hypoxia on triglyceride uptake in different tissues

Chronic intermittent hypoxia (CIH) inhibits plasma lipoprotein clearance and adipose lipoprotein lipase (LPL) activity in association with upregulation of an LPL inhibitor angiopoietin-like protein 4 (Angptl4). We hypothesize that CIH inhibits triglyceride (TG) uptake via Angptl4 and that an anti-Angptl4-neutralizing antibody would abolish the effects of CIH. Male C57BL/6J mice were exposed to four weeks of CIH or intermittent air (IA) while treated with Ab (30 mg/kg ip once a week). TG clearance was assessed by [H(3)]triolein administration retroorbitally. CIH delayed TG clearance and suppressed TG uptake and LPL activity in all white adipose tissue depots, brown adipose tissue, and lungs, whereas heart, liver, and spleen were not affected. CD146+ CD11b- pulmonary microvascular endothelial cells were responsible for TG uptake in the lungs and its inhibition by CIH. Antibody to Angptl4 decreased plasma TG levels and increased TG clearance and uptake into adipose tissue and lungs in both control and CIH mice to a similar extent, but did not reverse the effects of CIH. The antibody reversed the effects of CIH on LPL in adipose tissue and lungs. In conclusion, CIH inactivates LPL by upregulating Angptl4, but inhibition of TG uptake occurs predominantly via an Angptl4/LPL-independent mechanism.

Changes in fat metabolism of black-bone chickens during early stages of infection with Newcastle disease virus

Experiments were conducted to determine the effects of Newcastle disease on chicken fat metabolism. Thirty black-bone chickens were infected intraocularly with the Newcastle disease virus (NDV). Six birds were killed at 0, 12, 24, 48 and 72 h post infection, respectively. Results showed that the NDV infection decreased concentration of high-density lipoprotein cholesterol and increased concentrations of total cholesterol and low-density lipoprotein cholesterol in the plasma. Concentrations of triglycerides and free fatty acid were decreased after their initial increase. NDV infection also dramatically raised the activities of lipoprotein lipase (LPL), hepatic lipase and lipases in the serum. Furthermore, PCR results showed that the incipient infection up-regulated mRNA expression of LPL, adipose triglyceride lipase and nuclear factor peroxisome proliferator-activated receptor alpha (PPARα), but down-regulated them at later stage. Similarly, mRNA expression of fatty acid synthase, acetyl-CoA carboxylase and nuclear factor PPARγ, fatty acid transport protein 1 (FATP1), and 4(FATP4) decreased, whereas fatty acid translocase and fatty acid-binding protein increased initially. Data from Western blotting analysis showed that the changes in protein levels were consistent with mRNA expression. These results indicated that fat metabolism of the chicken was affected by the NDV infection. At the beginning of NDV infection, lipogenesis was inhibited, whereas lipolysis was strengthened. After lipolysis was strengthened, fat metabolism was found to be maximally depressed.

Ontogenic expression pattern and genetic polymorphisms of the fatty acid transport protein 4 (FATP4) gene in Chinese chicken populations

In the current research, the polymorphism of FATP4 gene was analyzed in Erlang Mountainous chickens. A total of nine genetic variants were identified by FATP4 gene sequencing analysis across the chicken samples. Significant associations (p < 0.05) were observed for two SNPs (g.5608778C>T and g.5608814G>A in exon 6) with certain carcass traits (such as live weight, carcass weight, eviscerated weight) in S01 and S05 populations, respectively. Meanwhile, in S05 population, haplotype 3 (T-G) and haplotype 2 (C-A) were associated with higher and lower partial carcass traits such as live weight, carcass weight, eviscerated weight and semi-eviscerated weight, respectively. Moreover, we investigated the expression profile of this gene during ontogenesis in Mountainous black-boned chicken. Quantitative real-time PCR analysis showed that FATP4 mRNA had the highest expression level in small intestine tissue over all other tissues examined. The FATP4 mRNA levels presented remarkable developmental changes with age in the various tissues. These results suggested that the FATP4 gene might play an important role in controlling chicken carcass traits.

Placental transfer of fatty acids and fetal implications

Considerable amounts of long-chain polyunsaturated fatty acids (LC-PUFAs), particularly arachidonic acid and docosahexaenoic acid (DHA, 22:6n-3), are deposited in fetal tissues during pregnancy; and this process is facilitated by placental delivery. Nevertheless, the mechanisms involved in LC-PUFA placental transfer remain unclear. Stable isotope techniques have been used to study human placental fatty acid transfer in vivo. These studies have shown a significantly higher ratio of (13)C-DHA in cord to maternal plasma compared with other fatty acids, which reflects a higher placental DHA transfer. In addition, a selective DHA accumulation in placental tissue, relative to other fatty acids, has been reported. The materno-fetal transfer of fatty acids is a slow process that requires ≥12 h. A high incorporation of dietary (13)C-DHA into maternal plasma phospholipids appears to be important for placental uptake and transfer. DHA in cord blood lipids correlates with placental messenger RNA expression of fatty acid transport protein (FATP)-4, compatible with a role of FATP-4 in DHA transfer. Impaired materno-fetal LC-PUFA transport has been proposed in pregnancies complicated by abnormal placental function (eg, due to gestational diabetes mellitus or intrauterine growth restriction), which should be addressed in future studies. Given that placental DHA transfer is important for child outcomes, elucidation of its potential modulation by transport mechanisms, maternal diet, and disease appears to be important.

In vivo and in vitro insulin and fasting control of the transmembrane fatty acid transport proteins in Atlantic salmon (Salmo salar)

We have examined the nutritional and insulin regulation of the mRNA expression of transmembrane fatty acid (FA) transporters [FA transport protein-1 (FATP1) and CD36] together with the lipoprotein lipase (LPL), the cytosolic FA carrier FA binding protein (FABP3), and mitochondrial FA-CoA and -carnitine palmitoyl transferase carriers (CPT)1 and -2 in Atlantic salmon tissues and myocyte cell culture. Two weeks of fasting diminished FATP1, CD36, and LPL in adipose tissue, suggesting a reduction in FA uptake, while FABP3 increased in liver, probably enhancing the transport of FA to the mitochondria. Insulin injection decreased FATP1 and CD36 in white and red muscles, while both transporters were upregulated in the adipose tissue in agreement with the role of insulin-inhibiting muscle FA oxidation and stimulating adipose fat stores. Serum deprivation of 48 h in Atlantic salmon myotubes increased FATP1, FABP3, and CPT-2, while CPT-1 was diminished. In myotubes, insulin induced FATP1 expression but decreased CD36, FABP3, and LPL, suggesting that FATP1 could be more involved in the insulin-stimulated FA uptake. Insulin increased the FA uptake in myotubes mediated, at least in part, through the relocation of FATP1 protein to the plasma membrane. Overall, Atlantic salmon FA transporters are regulated by fasting and insulin on in vivo and in vitro models.

Mechanisms of lipotoxicity in NAFLD and clinical implications

With the epidemic of childhood obesity, nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease in pediatrics. NAFLD is strongly associated with insulin resistance and increased level of serum free fatty acids (FFAs). FFAs have direct hepatotoxicity through the induction of an endoplasmic reticulum stress response and subsequently activation of the mitochondrial pathway of cell death. FFAs may also result in lysosomal dysfunction and alter death receptor gene expression. Lipoapoptosis is a key pathogenic process in NAFLD, and correlates with progressive inflammation, and fibrosis. Accumulation of triglyceride in the liver results from uptake and esterification of FFAs by the hepatocyte, and is less likely to be hepatotoxic per se. To date, there are no proven effective therapies that halt NAFLD progression or unfortunately improve prognosis in children. The cellular mechanisms of lipotoxicity are complex but provide potential therapeutic targets for NAFLD. In this review we discuss several potential therapeutic opportunities in detail including inhibition of apoptosis, c-Jun-N-terminal kinase, and endoplasmic reticulum stress pathways.

Caveolae and lipid trafficking in adipocytes

The abundance of caveolae in adipocytes suggests a possible cell-specific role for these structures, and because these cells take up and release fatty acids as their quantitatively most robust activity, modulation of fatty acid movement is one such role that is supported by substantial in vitro and in vivo data. In addition, caveolae are particularly rich in cholesterol and sphingolipids, and indeed, fat cells harbor more cholesterol than any other tissue. In this article, we review the role of adipocyte caveolae with regard to these important lipid classes.

Age-related expression profile of the SLC27A1 gene in chicken tissues

The solute carrier family 27 (SLC27, also known as fatty acid transport proteins [FATPs]) plays important biological roles in cells. However, there is no report about the expression profile of SLC27 member in chicken. In this study, we quantified the expression of SLC27A1 (FATP1) mRNA in a mountainous black-boned chicken breed (MB) and a commercial meat type chicken breed (S01), to discern the tissue and age-related specific expression pattern and their potential involvement in fat deposition and muscle fatty acid metabolism. Real-time quantitative PCR assays were developed for accurate measurement of SLC27A1 mRNA levels in different tissues from chicken with different ages (0-12 weeks). Expression of SLC27A1 mRNA was detected in all tissues examined. There was a significantly age-related change of the SLC27A1 mRNAs in heart, breast muscle (BMW), leg muscle (LMW), liver, and abdominal fat (AF) tissues (P < 0.05). The breast muscle and leg muscle tissues had the highest expression of SLC27A1 mRNA than the other tissues from the same individual at 0, 2 and 4 weeks. The overall SLC27A1 mRNA level exhibited a "rise-decline" developmental change in all tissues except for breast muscle, subcutaneous fat, and brain. The S01 chicken had a higher expression of the SLC27A1 mRNA in breast muscle, subcutaneous fat, and heart tissues than the MB chicken. Our results showed that the expression of SLC27A1 mRNA in chicken tissues exhibits specific developmental changes and age-related patterns.

Chylomicron- and VLDL-derived lipids enter the heart through different pathways: in vivo evidence for receptor- and non-receptor-mediated fatty acid uptake

Lipids circulate in the blood in association with plasma lipoproteins and enter the tissues either after hydrolysis or as non-hydrolyzable lipid esters. We studied cardiac lipids, lipoprotein lipid uptake, and gene expression in heart-specific lipoprotein lipase (LpL) knock-out (hLpL0), CD36 knock-out (Cd36(-/-)), and double knock-out (hLpL0/Cd36(-/-)-DKO) mice. Loss of either LpL or CD36 led to a significant reduction in heart total fatty acyl-CoA (control, 99.5 ± 3.8; hLpL0, 36.2 ± 3.5; Cd36(-/-), 57.7 ± 5.5 nmol/g, p < 0.05) and an additive effect was observed in the DKO (20.2 ± 1.4 nmol/g, p < 0.05). Myocardial VLDL-triglyceride (TG) uptake was reduced in the hLpL0 (31 ± 6%) and Cd36(-/-) (47 ± 4%) mice with an additive reduction in the DKO (64 ± 5%) compared with control. However, LpL but not CD36 deficiency decreased VLDL-cholesteryl ester uptake. Endogenously labeled mouse chylomicrons were produced by tamoxifen treatment of β-actin-MerCreMer/LpL(flox/flox) mice. Induced loss of LpL increased TG levels >10-fold and reduced HDL by >50%. After injection of these labeled chylomicrons in the different mice, chylomicron TG uptake was reduced by ∼70% and retinyl ester by ∼50% in hLpL0 hearts. Loss of CD36 did not alter either chylomicron TG or retinyl ester uptake. LpL loss did not affect uptake of remnant lipoproteins from ApoE knock-out mice. Our data are consistent with two pathways for fatty acid uptake; a CD36 process for VLDL-derived fatty acid and a non-CD36 process for chylomicron-derived fatty acid uptake. In addition, our data show that lipolysis is involved in uptake of core lipids from TG-rich lipoproteins.

Development and validation of a high-throughput screening assay for human long-chain fatty acid transport proteins 4 and 5

Dietary long-chain fatty acid (LCFA) uptake across cell membranes is mediated principally by fatty acid transport proteins (FATPs). Six subtypes of this transporter are differentially expressed throughout the human and rodent body. To facilitate drugs discovery against FATP subtypes, the authors used mammalian cell lines stably expressing the recombinant human FATP4 and 5 and developed a high-throughput screening (HTS) assay using a 96-well fluorometric imaging plate reader (FLIPR). LCFA uptake signal-to-background ratios were between 3- and 5-fold. Two 4-aryl-dihydropyrimidinones, j3 and j5, produced inhibition of FATP4 with a half-maximal inhibitory concentration (IC(50)) of 0.21 and 0.63 microM, respectively, and displayed approximately 100-fold selectivity over FATP5. The US Drug Collection library was screened against the FATP5. A hit rate of around 0.4% was observed with a Z' factor of 0.6 +/- 0.2. Two confirmed hits are bile acids, chenodiol and ursodiol with an IC(50) of 2.4 and 0.22 microM, respectively. To increase throughput, a single time point measurement in a 384-well format was developed using the Analyst HT, and the results are comparable with the 96-well format. In conclusion, the FATP4 and 5 cell-based fluorescence assays are suitable for a primary drug screen, whereas differentiated cell lines are useful for a secondary drug screen.

Association of FATP1 gene polymorphisms with chicken carcass traits in Chinese meat-type quality chicken populations

In this study, we aimed to detect the single nucleotide polymorphisms (SNPs) of the chicken FATP1 gene and discern the potential association between FATP1 SNPs and chicken carcass traits. A total of 620 meat-type quality chickens from six commercial pure lines (S01, S02, S03, S05, S06 and D99) and two cross lines (S05 × S01 and S06 × S01) were screened by using the single-strand conformational polymorphism analysis (SSCP) and DNA sequencing. Five SNPs [g.49360G > A, g.48195G > A, g.46847A > G, g.46818A > G, and g.46555A > G] were identified in chicken FATP1 gene. SNP g.46818 A > G was a rare variant and was not considered in the subsequent analysis. Sixteen haplotypes were reconstructed on the basis of the other four SNPs. The linear regression model analysis indicated that there were significant associations of certain diplotypes with part of carcass traits, such as live weight (LW), carcass weight (CW), and semi-eviscerated weight (SEW) (P < 0.05). In particular, diplotype H2H4 had a negative effect on LW, CW, SEW, and abdominal fat weight (AW); diplotype H6H10 had the highest reducing effect on subcutaneous fat thickness (SFT). Our results suggested that FATP1 gene polymorphisms were associated with chicken carcass traits or was linked with the major gene. The SNPs in this gene may be utilized as potential markers for marker-assisted selection (MAS) during chicken breeding.

Mechanisms and clinical implications of hepatocyte lipoapoptosis

Nonalcoholic fatty liver disease (NAFLD) is characterized by insulin resistance, elevated serum levels of free fatty acids (FFAs) and fatty infiltration of the liver. Accumulation of triglycerides in the hepatocyte results from the uptake and esterification of circulating FFAs by the liver. Contrary to current theory, hepatic steatosis appears to be a detoxification process, as FFAs are directly cytotoxic for the hepatocyte and inhibition of triglyceride formation enhances FFAs toxicity. Hepatocyte apoptosis is a key feature of NAFLD and correlates with disease severity. Since FFA-induced toxicity, or lipoapoptosis, represents a mechanism for the pathogenesis of NAFLD, this article will highlight the cellular pathways contributing to hepatocyte lipoapoptosis. To date, there is no proven effective therapy for patients with NAFLD and insights into the molecular mediators of lipoapoptosis should help promote effective therapeutic strategies for this disease.

Albumin as fatty acid transporter

SUMMARY

Fatty acids play critical roles in mammalian energy metabolism. Moreover, they are important substrates for the synthesis of membrane phospholipids and biologically active compounds like eicosanoids and leukotrienes. Because of their low solubility in aqueous solutions such as blood plasma and interstitial fluid, fatty acids are in need of binding proteins to increase their concentration in vascular and interstitial compartments. Albumin acts as main fatty acid binding protein in extracellular fluids. Plasma albumin possesses about 7 binding sites for fatty acids with moderate to high affinity, enhancing the concentration of fatty acids by a several orders of magnitude. Despite the high affinity of albumin for fatty acids, uptake of fatty acids by parenchymal cells such as skeletal and cardiac myocytes seems not to be hampered by albumin. In contrast, experimental findings suggest that albumin may facilitate the uptake of fatty acids by organs in need of these substrates. In the present overview the following issues will be briefly discussed: (i) transport and storage of fatty acids in the mammalian body, (ii) biosynthesis of albumin in the liver, (iii) localization and concentration of albumin in body fluids, (iv) interactions between albumin and fatty acids, (v) albumin structure and fatty acid binding sites, (vi) uptake of fatty acids by organs and roles for plasma albumin and (vii) lessons from patients and experimental animals lacking plasma albumin.