The Experts below are selected from a list of 1758 Experts worldwide ranked by ideXlab platform
Liqing Yu - One of the best experts on this subject based on the ideXlab platform.
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overexpression of NPC1L1 in the livers of transgenic bama miniature pigs accelerates lipid peroxidation
Genes & Genomics, 2015Co-Authors: Chongli Xu, Liqing Yu, Yuchen Gong, Xinping Duan, Xiaochun Tang, Mingjun Zhang, Daxin Pang, Hongsheng OuyangAbstract:Although Niemann-Pick C1-Like 1 (NPC1L1) plays a key role in intestinal cholesterol absorption, regulating cholesterol metabolism and maintaining cholesterol metabolic homeostasis, the molecular mechanism of NPC1L1 in lipid-metabolism disorders leading to liver disease remains largely unknown. Previous studies have shown that NPC1L1 is related with the development of fatty liver. Therefore, we hypothesized that NPC1L1 plays an important role in lipid-metabolism disorders and liver disease by affecting the transcription of certain genes involved in lipid synthesis. To further elucidate the function of NPC1L1, especially in the liver, we used somatic-cell nuclear transfer to establish transgenic pigs that expressed human NPC1L1 in their livers. We investigated superoxide dismutase activities and the levels of free fatty acids and malondialdehyde, a biomarker of lipid peroxidation. Superoxide dismutase activities significantly decreased, and free fatty acid and malondialdehyde levels significantly increased in the NPC1L1 transgenic pigs, indicating that the overexpression of NPC1L1 in the liver resulted in severe lipid peroxidation. Our findings suggest that NPC1L1 plays an important role in lipid-metabolism disorders and liver disease.
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genetic demonstration of intestinal NPC1L1 as a major determinant of hepatic cholesterol and blood atherogenic lipoprotein levels
Atherosclerosis, 2014Co-Authors: Weiqing Tang, Youlin Wang, Liqing YuAbstract:Abstract Objective : The correlation between intestinal cholesterol absorption values and plasma low-density lipoprotein-cholesterol (LDL-C) levels remains controversial. Niemann-Pick-C1-Like 1 (NPC1L1) is essential for intestinal cholesterol absorption, and is the target of ezetimibe, a cholesterol absorption inhibitor. However, studies with NPC1L1 knockout mice or ezetimibe cannot definitively clarify this correlation because NPC1L1 expression is not restricted to intestine in humans and mice. In this study we sought to genetically address this issue. Methods and results : We developed a mouse model that lacks endogenous (NPC1L1) and LDL receptor (LDLR) (DKO), but transgenically expresses human NPC1L1 in gastrointestinal tract only (DKO/L1 IntOnly mice). Our novel model eliminated potential effects of non-intestinal NPC1L1 on cholesterol homeostasis. We found that human NPC1L1 was localized at the intestinal brush border membrane of DKO/L1 IntOnly mice. Cholesterol feeding induced formation of NPC1L1-positive vesicles beneath this membrane in an ezetimibe-sensitive manner. Compared to DKO mice, DKO/L1 IntOnly mice showed significant increases in cholesterol absorption and blood/hepatic/biliary cholesterol. Increased blood cholesterol was restricted to very low-density lipoprotein (VLDL) and LDL fractions, which was associated with increased secretion and plasma levels of apolipoproteins B100 and B48. Additionally, DKO/L1 IntOnly mice displayed decreased fecal cholesterol excretion and hepatic/intestinal expression of cholesterologenic genes. Ezetimibe treatment virtually reversed all of the transgene-related phenotypes in DKO/L1 IntOnly mice. Conclusion : Our findings from DKO/L1 IntOnly mice clearly demonstrate that NPC1L1-mediated cholesterol absorption is a major determinant of blood levels of apolipoprotein B-containing atherogenic lipoproteins, at least in mice.
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niemann pick c1 like 1 NPC1L1 protein in intestinal and hepatic cholesterol transport
Annual Review of Physiology, 2011Co-Authors: Jenna L Betters, Liqing YuAbstract:Increased blood cholesterol is an independent risk factor for atherosclerotic cardiovascular disease. Cholesterol homeostasis in the body is controlled mainly by endogenous synthesis, intestinal absorption, and hepatic excretion. Niemann-Pick C1-Like 1 (NPC1L1) is a polytopic transmembrane protein localized at the apical membrane of enterocytes and the canalicular membrane of hepatocytes. It functions as a sterol transporter to mediate intestinal cholesterol absorption and counterbalances hepatobiliary cholesterol excretion. NPC1L1 is the molecular target of ezetimibe, a potent cholesterol absorption inhibitor that is widely used in treating hypercholesterolemia. Recent findings suggest that NPC1L1 deficiency or ezetimibe treatment also prevents diet-induced hepatic steatosis and obesity in addition to reducing blood cholesterol. Future studies should focus on molecular mechanisms underlying NPC1L1-dependent cholesterol transport and elucidation of how a cholesterol transporter modulates the pathogenesis ...
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NPC1L1 and cholesterol transport
FEBS Letters, 2010Co-Authors: Jenna L Betters, Liqing YuAbstract:The polytopic transmembrane protein, Niemann–Pick C1-Like 1 (NPC1L1), is enriched in the apical membrane of small intestine absorptive enterocytes where it mediates extracellular sterol transport across the brush border membrane. It is essential for intestinal sterol absorption and is the molecular target of ezetimibe, a potent cholesterol absorption inhibitor that lowers blood cholesterol in humans. NPC1L1 is also highly expressed in human liver. The hepatic function of NPC1L1 may be to limit excessive biliary cholesterol loss. NPC1L1-dependent sterol uptake seems to be a clathrin-mediated endocytic process and is regulated by cellular cholesterol content. Recently, NPC1L1 inhibition has been shown to have beneficial effects on components of the metabolic syndrome, such as obesity, insulin resistance, and fatty liver, in addition to atherosclerosis.
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diosgenin stimulation of fecal cholesterol excretion in mice is not NPC1L1 dependent
Journal of Lipid Research, 2009Co-Authors: Ryan E Temel, Lawrence L Rudel, Weiqing Tang, Yiannis A Ioannou, Joanna P Davies, Jonathan Mark Brown, Liqing YuAbstract:Diosgenin exists in some food supplements and herbal medicines and lowers plasma cholesterol by increasing fecal cholesterol excretion. It is believed that diosgenin promotes fecal cholesterol excretion by stimulating biliary cholesterol secretion and decreasing intestinal cholesterol absorption. Niemann-Pick C1-like 1 (NPC1L1) was recently identified as an essential protein for intestinal cholesterol absorption. To determine the relative contribution of biliary secretion and intestinal absorption of cholesterol in diosgenin-stimulated fecal cholesterol excretion, wild-type (WT) and NPC1L1-knockout (L1KO) mice were fed a diet with or without 1% diosgenin. Fecal cholesterol excretion (μmol/day/100 g body weight) increased in diosgenin-fed WT and L1KO mice from 4.2 to 52 and from 63 to 140, respectively. Surprisingly, this increase in diosgenin-treated versus untreated L1KO mice (77) was even greater than that seen in diosgenin-treated versus untreated WT mice (47.8). Additionally, WT and L1KO mice fed the diosgenin diet had similar increases in biliary cholesterol concentration, despite unaltered hepatic expression of the hepatobiliary cholesterol transporter, ATP binding cassette transporters G5 and G8. Facilitated cholesterol excretion in diosgenin-treated WT and L1KO mice was associated with decreased hepatic and plasma cholesterol and increased liver expression of cholesterol synthetic genes. In contrast, diosgenin had no effect on the intestinal expression of NPC1L1 and cholesterol synthetic genes. In an in vitro assay, diosgenin was unable to block NPC1L1-dependent cholesterol uptake. In conclusion, diosgenin stimulation of fecal cholesterol excretion is independent of NPC1L1-mediated cholesterol absorption.
Baoliang Song - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of NPC1L1 variants in uygur and kazakh with extreme low density lipoprotein cholesterol
Biochemical and Biophysical Research Communications, 2016Co-Authors: Qinghua Yuan, Honghua Miao, Boliang Li, Baoliang Song, Yuxiu Qu, Zhenyan Fu, Peishan Li, Jie XuAbstract:Abstract Background Plasma levels of low-density lipoprotein cholesterol (LDL-C) are a major risk factor for cardiovascular disease and are influenced by both heredity and dietary habits. The Niemann-Pick C1 like 1 (NPC1L1) protein mediates efficient dietary cholesterol absorption and contributes to variations in human LDL-C levels. Methods In the present study, using high throughput sequencing we identified three non-synonymous (NS) variations and 64 synonymous variations in the NPC1L1 gene from subsets of Chinese Han, Uygur and Kazakh populations with high or low LDL-C. Subsequently, three NS variations encoding R174H, V177I and V1284L substitutions were observed only in Uygur and Kazakh individuals with limited maximal plasma LDL-C levels. Results In further experiments, we investigated cholesterol-regulated recycling and glycosylation and stability of these NS NPC1L1 variants. However, no significant differences between WT and variant NPC1L1 proteins were observed using in vivo assays in mouse livers with adenovirus-mediated expression, demonstrating that none of the three NPC1L1 NS variants caused decreased uptake of biliary cholesterol. Conclusions Simultaneously, these data indicate that R174H, V177I and V1284L NPC1L1 variations in high or low LDL-C individuals may not directly influence cholesterol absorption by NPC1L1.
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the clathrin adaptor numb regulates intestinal cholesterol absorption through dynamic interaction with NPC1L1
Nature Medicine, 2014Co-Authors: Peishan Li, Jinhui Zhang, Boliang Li, Zhenyan Fu, Yingyu Zhang, Chenqi Xu, Baoliang SongAbstract:Bao-Liang Song and colleagues report that the clathrin adaptor Numb recognizes a peptide motif within the cholesterol transporter NPC1L1 upon cholesterol binding and thus facilitates dietary cholesterol uptake into the gut. Inhibition of this Numb-NPC1L1 interaction in mice reduces serum cholesterol levels and thus may be a therapeutic target to treat hypercholesterolemia in the clinic.
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the small gtpase cdc42 interacts with niemann pick c1 like 1 NPC1L1 and controls its movement from endocytic recycling compartment to plasma membrane in a cholesterol dependent manner
Journal of Biological Chemistry, 2011Co-Authors: Na Li, Boliang Li, Zhengjun Chen, Baoliang SongAbstract:Niemann-Pick C1-like 1 (NPC1L1) is a multi-transmembrane protein that mediates the absorption of dietary and biliary cholesterol through vesicular endocytosis. The subcellular localization of NPC1L1 is regulated by cholesterol. Cholesterol depletion induces the transport of NPC1L1 to plasma membrane (PM) from endocytic recycling compartment that requires MyoVb·Rab11a·Rab11-FIP2 triple complex, and cholesterol-replenishment renders the internalization of NPC1L1 together with cholesterol. Here, we find that GTP-bound Cdc42 interacts with NPC1L1. Cholesterol depletion regulates the activation of Cdc42 and enhances NPC1L1-Cdc42 interaction. Overexpression of constitutive GTP-bound Cdc42 mutant form or knockdown of Cdc42 inhibits the transport of NPC1L1 to the PM and disturbs the cholesterol-regulated binding of NPC1L1 to Rab11a, MyoVb, and actin. Knockdown of Cdc42 downstream effectors N-WASP or Arp3 also leads to the similar results. In liver-specific Cdc42 knock-out (Cdc42 LKO) mice, NPC1L1 fails to localize to bile canaliculi, and the biliary cholesterol cannot be efficiently reabsorbed. These results indicate that Cdc42 controls the cholesterol-regulated transport and localization of NPC1L1, and plays a role in cholesterol absorption.
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the n terminal domain of NPC1L1 protein binds cholesterol and plays essential roles in cholesterol uptake
Journal of Biological Chemistry, 2011Co-Authors: Jinhui Zhang, Liang Ge, Wei Qi, Liqing Zhang, Honghua Miao, Boliang Li, Maojun Yang, Baoliang SongAbstract:Niemann-Pick C1-like 1 (NPC1L1) is a multitransmembrane protein playing a crucial role in dietary and biliary cholesterol absorption. Cholesterol promotes the formation and endocytosis of NPC1L1-flotillin-cholesterol membrane microdomains, which is an early step in cholesterol uptake. How cholesterol is sensed in this step is unknown. Here, we find that the N-terminal domain (NTD) of NPC1L1 binds cholesterol. Mutation of residue Leu-216 in NPC1L1-NTD eliminates cholesterol binding, decreases the formation of NPC1L1-flotillin-cholesterol membrane microdomains, and prevents NPC1L1-mediated cholesterol uptake in culture cells and mice livers. NPC1L1-NTD specifically binds cholesterol but not plant sterols, which may account for the selective cholesterol absorption in intestine. Furthermore, 25- or 27-hydroxycholesterol competes with cholesterol to bind NPC1L1-NTD and inhibits the cholesterol induced endocytosis of NPC1L1. Together, these results demonstrate that plasma membrane-localized NPC1L1 binds exogenous cholesterol via its NTD, and facilitates the formation of NPC1L1-flotillin-cholesterol membrane microdomains that are then internalized into cells through the clathrin-AP2 pathway. Our study uncovers the mechanism of cholesterol sensing by NPC1L1 and proposes a mechanism for selective cholesterol absorption.
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molecular characterization of the NPC1L1 variants identified from cholesterol low absorbers
Journal of Biological Chemistry, 2011Co-Authors: Lijuan Wang, Liang Ge, Boliang Li, Jing Wang, Na Li, Baoliang SongAbstract:Niemann-Pick C1-like 1 (NPC1L1) is an essential protein for dietary cholesterol absorption. Nonsynonymous (NS) variants of NPC1L1 in humans have been suggested to associate with cholesterol absorption variations. However, information concerning the characteristics and mechanism of these variants in cholesterol uptake is limited. In this study, we analyzed the cholesterol uptake ability of the 19 reported NS variants of NPC1L1 identified from cholesterol low absorbers. Among these variants, L110F, R306C, A395V, G402S, T413M, R693C, R1214H, and R1268H could partially mediate cellular cholesterol uptake and were categorized as partially dysfunctional variants. The other 11 variants including T61M, N132S, D398G, R417W, G434R, T499M, S620C, I647N, G672R, S881L, and R1108W could barely facilitate cholesterol uptake, and were classified into the severely dysfunctional group. The partially dysfunctional variants showed mild defects in one or multiple aspects of cholesterol-regulated recycling, subcellular localization, glycosylation, and protein stability. The severely dysfunctional ones displayed remarkable defects in all these aspects and were rapidly degraded through the ER-associated degradation (ERAD) pathway. In vivo analyses using adenovirus-mediated expression in mouse liver confirmed that the S881L variant failed to localize to liver canalicular membrane, and the mice showed defects in biliary cholesterol re-absorption, while the G402S variant appeared to be similar to wild-type NPC1L1 in mouse liver. This study suggests that the dysfunction of the 19 variants on cholesterol absorption is due to the impairment of recycling, subcellular localization, glycosylation, or stability of NPC1L1.
Scott W Altmann - One of the best experts on this subject based on the ideXlab platform.
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niemann pick c1 like 1 NPC1L1 an intestinal sterol transporter
Biochimica et Biophysica Acta, 2009Co-Authors: Harry R Davis, Scott W AltmannAbstract:Abstract Niemann–Pick C1 Like 1 (NPC1L1) has been identified and characterized as an essential protein in the intestinal cholesterol absorption process. NPC1L1 localizes to the brush border membrane of absorptive enterocytes in the small intestine. Intestinal expression of NPC1L1 is down regulated by diets containing high levels of cholesterol. While otherwise phenotypically normal, NPC1L1 null mice exhibit a significant reduction in the intestinal uptake and absorption of cholesterol and phytosterols. Characterization of the NPC1L1 pathway revealed that cholesterol absorption inhibitor ezetimibe specifically binds to an extracellular loop of NPC1L1 and inhibits its sterol transport function. NPC1L1 null mice are resistant to diet-induced hypercholesterolemia, and when crossed with apo E null mice, are completely resistant to the development of atherosclerosis. Intestinal gene expression studies in NPC1L1 null mice indicated that no exogenous cholesterol was entering enterocytes lacking NPC1L1, which resulted in an upregulation of intestinal and hepatic LDL receptor and cholesterol biosynthetic gene expression. Polymorphisms in the human NPC1L1 gene have been found to influence cholesterol absorption and plasma low density lipoprotein levels. Therefore, NPC1L1 is a critical intestinal sterol uptake transporter which influences whole body cholesterol homeostasis.
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Niemann–Pick C1 Like 1 (NPC1L1) an intestinal sterol transporter
Biochimica et Biophysica Acta, 2009Co-Authors: Harry R Davis, Scott W AltmannAbstract:Abstract Niemann–Pick C1 Like 1 (NPC1L1) has been identified and characterized as an essential protein in the intestinal cholesterol absorption process. NPC1L1 localizes to the brush border membrane of absorptive enterocytes in the small intestine. Intestinal expression of NPC1L1 is down regulated by diets containing high levels of cholesterol. While otherwise phenotypically normal, NPC1L1 null mice exhibit a significant reduction in the intestinal uptake and absorption of cholesterol and phytosterols. Characterization of the NPC1L1 pathway revealed that cholesterol absorption inhibitor ezetimibe specifically binds to an extracellular loop of NPC1L1 and inhibits its sterol transport function. NPC1L1 null mice are resistant to diet-induced hypercholesterolemia, and when crossed with apo E null mice, are completely resistant to the development of atherosclerosis. Intestinal gene expression studies in NPC1L1 null mice indicated that no exogenous cholesterol was entering enterocytes lacking NPC1L1, which resulted in an upregulation of intestinal and hepatic LDL receptor and cholesterol biosynthetic gene expression. Polymorphisms in the human NPC1L1 gene have been found to influence cholesterol absorption and plasma low density lipoprotein levels. Therefore, NPC1L1 is a critical intestinal sterol uptake transporter which influences whole body cholesterol homeostasis.
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cholesterol homeostasis by the intestine lessons from niemann pick c1 like 1 NPC1L1
Atherosclerosis Supplements, 2008Co-Authors: Harry R Davis, Federica Basso, Lizbeth M Hoos, Glen Tetzloff, Sean M Lally, Scott W AltmannAbstract:Abstract Ezetimibe is a selective cholesterol absorption inhibitor, which potently inhibits the uptake and absorption of biliary and dietary cholesterol from the small intestine without affecting the absorption of fat-soluble vitamins, triglycerides or bile acids. Identification and characterization of Niemann-Pick C1 Like 1 (NPC1L1) has established NPC1L1 as an essential protein in the intestinal cholesterol absorption process. While otherwise phenotypically normal, NPC1L1 null mice exhibit a significant reduction in the intestinal uptake and absorption of cholesterol and phytosterols. Characterization of the NPC1L1 pathway revealed that ezetimibe specifically binds to NPC1L1 and inhibits its sterol transport function. NPC1L1 null mice were resistant to diet-induced hypercholesterolemia, and when crossed with apoE null mice, were completely resistant to the development of atherosclerosis. In NPC1L1/apoE null mice or apoE null mice treated with ezetimibe plasma cholesterol levels were reduced primarily in the apoB48 containing chylomicron remnant lipoproteins relative to untreated apoE null mice. SR-B1 has been proposed to play a role in intestinal cholesterol uptake, but in NPC1L1/SR-B1 double null mice intestinal cholesterol absorption was not different than NPC1L1 null alone mice. Therefore, NPC1L1 is the critical intestinal sterol transporter which influences whole body cholesterol homeostasis, and is the molecular target of ezetimibe.
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in vivo responsiveness to ezetimibe correlates with niemann pick c1 like 1 NPC1L1 binding affinity comparison of multiple species NPC1L1 orthologs
Molecular Pharmacology, 2007Co-Authors: Brian E Hawes, Harry R Davis, James H Crona, Michael P Graziano, Kim Oneill, Scott W AltmannAbstract:Ezetimibe is the first in class 2-azetidinone that decreases plasma cholesterol by blocking intestinal cholesterol absorption. Ezetimibe effectively reduces plasma cholesterol in several species including human, monkey, dog, hamster, rat, and mouse, but the potency ranges widely. One potential factor responsible for this variation in responsiveness is diversity in ezetimibe metabolism. After oral administration, ezetimibe is glucuronidated. Both ezetimibe and the glucuronide lower plasma cholesterol; however, the glucuronide exhibits greater potency. Recent identification of Niemann-Pick C1 Like-1 (NPC1L1) as the molecular target of ezetimibe enables direct binding studies to be performed. Here, we report the cloning of NPC1L1 derived from multiple species and assess amino acid sequence homology among human, monkey, dog, hamster, rat, and mouse. The rank order of affinity of glucuronidated ezetimibe for NPC1L1 in each species correlates with the rank order of in vivo activity with monkey > dog > hamster and rat ≫ mouse. Ezetimibe analogs that bind to NPC1L1 exhibit in vivo cholesterol-lowering activity, whereas compounds that do not bind NPC1L1 are inactive. Specific structural components of ezetimibe are identified as critical for binding to NPC1L1. The results demonstrate that small variations in ezetimibe structure or in NPC1L1 amino acid sequence can profoundly influence ezetimibe/NPC1L1 interaction and consequently in vivo activity. The results demonstrate that the ability of compounds to bind to NPC1L1 is the major determinant of in vivo responsiveness.
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characterization of the putative native and recombinant rat sterol transporter niemann pick c1 like 1 NPC1L1 protein
Biochimica et Biophysica Acta, 2005Co-Authors: Sai Prasad N Iyer, Harry R Davis, Lizbeth M Hoos, Glen Tetzloff, James H Crona, Michael P Graziano, Scott W AltmannAbstract:Abstract The exact mechanistic pathway of cholesterol absorption in the jejunum of the small intestines is a poorly understood process. Recently, a relatively novel gene, Niemann-Pick C1 Like 1 (NPC1L1), was identified as being critical for intestinal sterol absorption in a pathway which is sensitive to sterol absorption inhibitors such as ezetimibe. NPC1L1 is a multi-transmembrane protein, with a putative sterol sensing domain. Very little else is known about the NPC1L1 protein. In this report, we characterize the native and recombinant rat NPC1L1 protein. We show that NPC1L1 is a 145 kDa membrane protein, enriched in the brush border membrane of the intestinal enterocyte and is highly glycosylated. In addition, sequential detergent extraction of enterocytes result in highly enriched preparations of NPC1L1. An engineered Flag epitope tagged rat NPC1L1 cDNA was expressed as recombinant protein in CHO cells and demonstrated cell surface expression, similar to the native rat protein. These biochemical data indicate that NPC1L1 exists as a predominantly cell surface membrane expressed protein, consistent with its proposed role as the putative intestinal sterol transporter.
Hiroshi Suzuki - One of the best experts on this subject based on the ideXlab platform.
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pathophysiological importance of bile cholesterol reabsorption hepatic NPC1L1 exacerbated steatosis and decreasing vldl tg secretion in mice fed a high fat diet
Lipids in Health and Disease, 2019Co-Authors: Yu Toyoda, Tappei Takada, Yoshihide Yamanashi, Hiroshi SuzukiAbstract:Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide, although its pathogenesis remains to be elucidated. A recent study revealed that hepatic Niemann-Pick C1-Like 1 (NPC1L1), a cholesterol re-absorber from bile to the liver expressed on the bile canalicular membrane, is an exacerbation factor of NAFLD. Indeed, transgenic mice with hepatic expression of human NPC1L1 under a liver-specific promoter (L1-Tg mice) developed steatosis with a high-fat diet (HFD) containing cholesterol within a few weeks. However, the mechanism underlying diet-induced hepatic NPC1L1-mediated lipid accumulation is poorly defined. To achieve a deeper understanding of steatosis development in L1-Tg mice, the biochemical features of hepatic NPC1L1-mediated steatosis were investigated. Hemizygous L1-Tg mice and wild-type littermate controls fed a HFD or control-fat diet were used. At the indicated time points, the livers were evaluated for cholesterol and triglyceride (TG) contents as well as mRNA levels of hepatic genes involved in the maintenance of lipid homeostasis. The hepatic ability to secrete very low-density lipoprotein (VLDL)-TG was also investigated. Unlike the livers of wild-type mice that have little expression of hepatic NPC1L1, the livers of L1-Tg mice displayed time-dependent changes that indicated steatosis formation. In steatosis, there were three different stages of development: mild accumulation of hepatic cholesterol and TG (early stage), acceleration of hepatic TG accumulation (middle stage), and further accumulation of hepatic cholesterol (late stage). In the early stage, between WT and L1-Tg mice fed a HFD for 2 weeks, there were no significant differences in the hepatic expression of Pparα, Acox1, Fat/Cd36, Srebf1, and Srebf2; however, the hepatic ability to secrete VLDL-TG decreased in L1-Tg mice (P < 0.05). Furthermore, this decrease was completely prevented by administration of ezetimibe, an NPC1L1-selective inhibitor. Hepatic NPC1L1 exacerbates diet-induced steatosis, which was accompanied by decreased hepatic ability of VLDL-TG secretion. The obtained results provide a deeper understanding of L1-Tg mice as a promising NAFLD animal model that is able to re-absorb biliary-secreted cholesterol similar to humans. Furthermore, this work supports further studies of the pathophysiological impact of re-absorbed biliary cholesterol on the regulation of hepatic lipid homeostasis.
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identification of hepatic NPC1L1 as an nafld risk factor evidenced by ezetimibe mediated steatosis prevention and recovery
FASEB bioAdvances, 2019Co-Authors: Yu Toyoda, Tappei Takada, Masakazu Umezawa, Fumiya Tomura, Yoshihide Yamanashi, Ken Takeda, Hiroshi SuzukiAbstract:Non‐alcoholic fatty liver disease (NAFLD) is a serious global public health concern. Nevertheless, there are no specific medications for treating the associated abnormal accumulation of hepatic lipids such as cholesterol and triglycerides. While seminal findings suggest a link between hepatic cholesterol accumulation and NAFLD progression, the molecular bases of these associations are not well understood. Here, we experimentally demonstrate that hepatic Niemann‐Pick C1‐Like 1 (NPC1L1), a cholesterol re‐absorber from bile to the liver, can cause steatosis, an early stage of NAFLD using genetically engineered L1‐Tg mice characterized by hepatic expression of NPC1L1 under the control of ApoE promoter. Contrary to wild‐type mice that have little expression of hepatic NPC1L1, the livers of L1‐Tg mice fed a high‐fat diet became steatotic within only a few weeks. Moreover, hepatic NPC1L1‐mediated steatosis was not only prevented, but completely rescued, by orally administered ezetimibe, a well‐used lipid‐lowering drug on the global market, even under high‐fat diet feedings. These results indicate that hepatic NPC1L1 is an NAFLD‐exacerbating factor amendable to therapeutic intervention and would extend our understanding of the vital role of cholesterol uptake from bile in the development of NAFLD. Furthermore, administration of a TLR4 inhibitor also prevented the hepatic NPC1L1‐mediated steatosis formation, suggesting a latent link between physiological roles of hepatic NPC1L1 and regulation of innate immune system. Our results revealed that hepatic NPC1L1 is a novel NAFLD risk factor contributing to steatosis formation that is rescued by ezetimibe; additionally, our findings uncover feasible opportunities for repositioning drugs to treat NAFLD in the near future.
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Identification of hepatic NPC1L1 as an NAFLD risk factor evidenced by ezetimibe‐mediated steatosis prevention and recovery
FASEB bioAdvances, 2019Co-Authors: Yu Toyoda, Tappei Takada, Masakazu Umezawa, Fumiya Tomura, Yoshihide Yamanashi, Ken Takeda, Hiroshi SuzukiAbstract:Non‐alcoholic fatty liver disease (NAFLD) is a serious global public health concern. Nevertheless, there are no specific medications for treating the associated abnormal accumulation of hepatic lipids such as cholesterol and triglycerides. While seminal findings suggest a link between hepatic cholesterol accumulation and NAFLD progression, the molecular bases of these associations are not well understood. Here, we experimentally demonstrate that hepatic Niemann‐Pick C1‐Like 1 (NPC1L1), a cholesterol re‐absorber from bile to the liver, can cause steatosis, an early stage of NAFLD using genetically engineered L1‐Tg mice characterized by hepatic expression of NPC1L1 under the control of ApoE promoter. Contrary to wild‐type mice that have little expression of hepatic NPC1L1, the livers of L1‐Tg mice fed a high‐fat diet became steatotic within only a few weeks. Moreover, hepatic NPC1L1‐mediated steatosis was not only prevented, but completely rescued, by orally administered ezetimibe, a well‐used lipid‐lowering drug on the global market, even under high‐fat diet feedings. These results indicate that hepatic NPC1L1 is an NAFLD‐exacerbating factor amendable to therapeutic intervention and would extend our understanding of the vital role of cholesterol uptake from bile in the development of NAFLD. Furthermore, administration of a TLR4 inhibitor also prevented the hepatic NPC1L1‐mediated steatosis formation, suggesting a latent link between physiological roles of hepatic NPC1L1 and regulation of innate immune system. Our results revealed that hepatic NPC1L1 is a novel NAFLD risk factor contributing to steatosis formation that is rescued by ezetimibe; additionally, our findings uncover feasible opportunities for repositioning drugs to treat NAFLD in the near future.
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NPC1L1 is a key regulator of intestinal vitamin k absorption and a modulator of warfarin therapy
Science Translational Medicine, 2015Co-Authors: Tappei Takada, Yu Toyoda, Yoshihide Yamanashi, Kentaro Konishi, Takehito Yamamoto, Yusuke Masuo, Hideaki Yamamoto, Hiroshi SuzukiAbstract:Vitamin K (VK) is a micronutrient that facilitates blood coagulation. VK antagonists, such as warfarin, are used in the clinic to prevent thromboembolism. Because VK is not synthesized in the body, its intestinal absorption is crucial for maintaining whole-body VK levels. However, the molecular mechanism of this absorption is unclear. We demonstrate that Niemann-Pick C1-like 1 (NPC1L1) protein, a cholesterol transporter, plays a central role in intestinal VK uptake and modulates the anticoagulant effect of warfarin. In vitro studies using NPC1L1-overexpressing intestinal cells and in vivo studies with NPC1L1 -knockout mice revealed that intestinal VK absorption is NPC1L1-dependent and inhibited by ezetimibe, an NPC1L1-selective inhibitor clinically used for dyslipidemia. In addition, in vivo pharmacological studies demonstrated that the coadministration of ezetimibe and warfarin caused a reduction in hepatic VK levels and enhanced the pharmacological effect of warfarin. Adverse events caused by the coadministration of ezetimibe and warfarin were rescued by oral VK supplementation, suggesting that the drug-drug interaction effects observed were the consequence of ezetimibe-mediated VK malabsorption. This mechanism was supported by a retrospective evaluation of clinical data showing that, in more than 85% of warfarin-treated patients, the anticoagulant activity was enhanced by cotreatment with ezetimibe. Our findings provide insight into the molecular mechanism of VK absorption. This new drug-drug interaction mechanism between ezetimibe (a cholesterol transport inhibitor) and warfarin (a VK antagonist and anticoagulant) could inform clinical care of patients on these medications, such as by altering the kinetics of essential, fat-soluble vitamins.
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human NPC1L1 expression is positively regulated by pparα
Pharmaceutical Research, 2011Co-Authors: Yuki Iwayanagi, Tappei Takada, Fumiya Tomura, Yoshihide Yamanashi, Tomohiro Terada, Kenichi Inui, Hiroshi SuzukiAbstract:Purpose Niemann-Pick C1-like 1 (NPC1L1), a pharmacological target of ezetimibe, is responsible for cholesterol absorption in enterocytes and hepatocytes. In the present study, the involvement of peroxisome proliferator-activated receptor α (PPARα) and its cofactor, PPARγ coactivator 1α (PGC1α) in the transcriptional regulation of human NPC1L1 was analyzed.
Boliang Li - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of NPC1L1 variants in uygur and kazakh with extreme low density lipoprotein cholesterol
Biochemical and Biophysical Research Communications, 2016Co-Authors: Qinghua Yuan, Honghua Miao, Boliang Li, Baoliang Song, Yuxiu Qu, Zhenyan Fu, Peishan Li, Jie XuAbstract:Abstract Background Plasma levels of low-density lipoprotein cholesterol (LDL-C) are a major risk factor for cardiovascular disease and are influenced by both heredity and dietary habits. The Niemann-Pick C1 like 1 (NPC1L1) protein mediates efficient dietary cholesterol absorption and contributes to variations in human LDL-C levels. Methods In the present study, using high throughput sequencing we identified three non-synonymous (NS) variations and 64 synonymous variations in the NPC1L1 gene from subsets of Chinese Han, Uygur and Kazakh populations with high or low LDL-C. Subsequently, three NS variations encoding R174H, V177I and V1284L substitutions were observed only in Uygur and Kazakh individuals with limited maximal plasma LDL-C levels. Results In further experiments, we investigated cholesterol-regulated recycling and glycosylation and stability of these NS NPC1L1 variants. However, no significant differences between WT and variant NPC1L1 proteins were observed using in vivo assays in mouse livers with adenovirus-mediated expression, demonstrating that none of the three NPC1L1 NS variants caused decreased uptake of biliary cholesterol. Conclusions Simultaneously, these data indicate that R174H, V177I and V1284L NPC1L1 variations in high or low LDL-C individuals may not directly influence cholesterol absorption by NPC1L1.
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the clathrin adaptor numb regulates intestinal cholesterol absorption through dynamic interaction with NPC1L1
Nature Medicine, 2014Co-Authors: Peishan Li, Jinhui Zhang, Boliang Li, Zhenyan Fu, Yingyu Zhang, Chenqi Xu, Baoliang SongAbstract:Bao-Liang Song and colleagues report that the clathrin adaptor Numb recognizes a peptide motif within the cholesterol transporter NPC1L1 upon cholesterol binding and thus facilitates dietary cholesterol uptake into the gut. Inhibition of this Numb-NPC1L1 interaction in mice reduces serum cholesterol levels and thus may be a therapeutic target to treat hypercholesterolemia in the clinic.
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the small gtpase cdc42 interacts with niemann pick c1 like 1 NPC1L1 and controls its movement from endocytic recycling compartment to plasma membrane in a cholesterol dependent manner
Journal of Biological Chemistry, 2011Co-Authors: Na Li, Boliang Li, Zhengjun Chen, Baoliang SongAbstract:Niemann-Pick C1-like 1 (NPC1L1) is a multi-transmembrane protein that mediates the absorption of dietary and biliary cholesterol through vesicular endocytosis. The subcellular localization of NPC1L1 is regulated by cholesterol. Cholesterol depletion induces the transport of NPC1L1 to plasma membrane (PM) from endocytic recycling compartment that requires MyoVb·Rab11a·Rab11-FIP2 triple complex, and cholesterol-replenishment renders the internalization of NPC1L1 together with cholesterol. Here, we find that GTP-bound Cdc42 interacts with NPC1L1. Cholesterol depletion regulates the activation of Cdc42 and enhances NPC1L1-Cdc42 interaction. Overexpression of constitutive GTP-bound Cdc42 mutant form or knockdown of Cdc42 inhibits the transport of NPC1L1 to the PM and disturbs the cholesterol-regulated binding of NPC1L1 to Rab11a, MyoVb, and actin. Knockdown of Cdc42 downstream effectors N-WASP or Arp3 also leads to the similar results. In liver-specific Cdc42 knock-out (Cdc42 LKO) mice, NPC1L1 fails to localize to bile canaliculi, and the biliary cholesterol cannot be efficiently reabsorbed. These results indicate that Cdc42 controls the cholesterol-regulated transport and localization of NPC1L1, and plays a role in cholesterol absorption.
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the n terminal domain of NPC1L1 protein binds cholesterol and plays essential roles in cholesterol uptake
Journal of Biological Chemistry, 2011Co-Authors: Jinhui Zhang, Liang Ge, Wei Qi, Liqing Zhang, Honghua Miao, Boliang Li, Maojun Yang, Baoliang SongAbstract:Niemann-Pick C1-like 1 (NPC1L1) is a multitransmembrane protein playing a crucial role in dietary and biliary cholesterol absorption. Cholesterol promotes the formation and endocytosis of NPC1L1-flotillin-cholesterol membrane microdomains, which is an early step in cholesterol uptake. How cholesterol is sensed in this step is unknown. Here, we find that the N-terminal domain (NTD) of NPC1L1 binds cholesterol. Mutation of residue Leu-216 in NPC1L1-NTD eliminates cholesterol binding, decreases the formation of NPC1L1-flotillin-cholesterol membrane microdomains, and prevents NPC1L1-mediated cholesterol uptake in culture cells and mice livers. NPC1L1-NTD specifically binds cholesterol but not plant sterols, which may account for the selective cholesterol absorption in intestine. Furthermore, 25- or 27-hydroxycholesterol competes with cholesterol to bind NPC1L1-NTD and inhibits the cholesterol induced endocytosis of NPC1L1. Together, these results demonstrate that plasma membrane-localized NPC1L1 binds exogenous cholesterol via its NTD, and facilitates the formation of NPC1L1-flotillin-cholesterol membrane microdomains that are then internalized into cells through the clathrin-AP2 pathway. Our study uncovers the mechanism of cholesterol sensing by NPC1L1 and proposes a mechanism for selective cholesterol absorption.
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molecular characterization of the NPC1L1 variants identified from cholesterol low absorbers
Journal of Biological Chemistry, 2011Co-Authors: Lijuan Wang, Liang Ge, Boliang Li, Jing Wang, Na Li, Baoliang SongAbstract:Niemann-Pick C1-like 1 (NPC1L1) is an essential protein for dietary cholesterol absorption. Nonsynonymous (NS) variants of NPC1L1 in humans have been suggested to associate with cholesterol absorption variations. However, information concerning the characteristics and mechanism of these variants in cholesterol uptake is limited. In this study, we analyzed the cholesterol uptake ability of the 19 reported NS variants of NPC1L1 identified from cholesterol low absorbers. Among these variants, L110F, R306C, A395V, G402S, T413M, R693C, R1214H, and R1268H could partially mediate cellular cholesterol uptake and were categorized as partially dysfunctional variants. The other 11 variants including T61M, N132S, D398G, R417W, G434R, T499M, S620C, I647N, G672R, S881L, and R1108W could barely facilitate cholesterol uptake, and were classified into the severely dysfunctional group. The partially dysfunctional variants showed mild defects in one or multiple aspects of cholesterol-regulated recycling, subcellular localization, glycosylation, and protein stability. The severely dysfunctional ones displayed remarkable defects in all these aspects and were rapidly degraded through the ER-associated degradation (ERAD) pathway. In vivo analyses using adenovirus-mediated expression in mouse liver confirmed that the S881L variant failed to localize to liver canalicular membrane, and the mice showed defects in biliary cholesterol re-absorption, while the G402S variant appeared to be similar to wild-type NPC1L1 in mouse liver. This study suggests that the dysfunction of the 19 variants on cholesterol absorption is due to the impairment of recycling, subcellular localization, glycosylation, or stability of NPC1L1.
