1
|
André R, Pacheco R, Alves AC, Santos HM, Bourbon M, Serralheiro ML. The Hypocholesterolemic Potential of the Edible Algae Fucus vesiculosus: Proteomic and Quantitative PCR Analysis. Foods 2023; 12:2758. [PMID: 37509850 PMCID: PMC10379601 DOI: 10.3390/foods12142758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/29/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
A brown seaweed consumed worldwide, Fucus vesiculosus, has been used to prevent atherosclerosis and hypercholesterolemia, among other uses. However, the mechanisms of action that lead to these effects are not yet fully understood. This work aims to study the in vitro effect of an aqueous extract of F. vesiculosus, previously characterized as rich in phlorotannins and peptides, on the expression of different proteins involved in the synthesis and transport of cholesterol. A proteomic analysis, Western blot, and qRT-PCR analysis were performed to identify protein changes in HepG2 cells exposed to 0.25 mg/mL of the F. vesiculosus extract for 24 h. The proteomic results demonstrated that, in liver cells, the extract decreases the expression of four proteins involved in the cholesterol biosynthesis process (CYP51A1, DHCR24, HMGCS1 and HSD17B7). Additionally, a 12.76% and 18.40% decrease in the expression of two important transporters proteins of cholesterol, NPC1L1 and ABCG5, respectively, was also observed, as well as a 30% decrease in NPC1L1 mRNA levels in the cells exposed to the extract compared to control cells. Our study reveals some of the mechanisms underlying the actions of bioactive compounds from F. vesiculosus that may explain its previously reported hypocholesterolemic effect, future prospecting its use as a functional food.
Collapse
Affiliation(s)
- Rebeca André
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Rita Pacheco
- Department of Chemical Engineering, ISEL-Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal
- Centro de Química Estrutural, Institute of Molecular Sciences, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Ana Catarina Alves
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Unidade de I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal
| | - Hugo M Santos
- LAQV@REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- PROTEOMASS Scientific Society, Madan Park, Rúa dos Inventores, 2825-182 Caparica, Portugal
| | - Mafalda Bourbon
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Unidade de I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal
| | - Maria Luísa Serralheiro
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- Department of Chemistry and Biochemistry, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, C8 Bldg, 1749-016 Lisboa, Portugal
| |
Collapse
|
2
|
Wang Y, Yang P, Zhang B, Ding Y, Lei S, Hou Y, Guan X, Li Q. Hepatic NPC1L1 overexpression attenuates alcoholic autophagy in mice. Mol Med Rep 2019; 20:3224-3232. [PMID: 31432115 PMCID: PMC6755247 DOI: 10.3892/mmr.2019.10549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 06/27/2019] [Indexed: 01/25/2023] Open
Abstract
Alcohol consumption causes liver steatosis in humans. Metabolic disorders of lipids are one of the factors that cause liver steatosis in hepatocytes. Hepatic Niemann‑Pick C1‑like 1 (NPC1L1) regulates lipid homeostasis in mammals. The relationship between NPC1L1 and autophagy in those with a history of alcohol abuse is unclear. The present study aimed to investigate the function of NPC1L1 in the activation of hepatic autophagy in a mouse model with a human (h)NPC1L1 transgene under alcohol feeding conditions. The mice expressing hNPC1L1 (Ad‑L1) or controls (Ad‑null) were created by retro‑orbital adenovirus injection. The Ad‑L1 and Ad‑null mice were fed with alcohol or a non‑alcoholic diet to mimic chronic alcohol consumption in humans. Hepatic autophagy was demonstrated in isolated primary hepatocytes by monitoring autophagic vacuoles under fluorescence microscopy, and by western blotting for autophagic makers. Isolated hepatocytes from the livers of Ad‑L1 mice were treated with different doses of ezetimibe to study the restoration of autophagy. Chronic alcohol feeding caused liver injury and steatosis, shown by significantly higher levels of plasma alanine transaminase and aspartate transaminase activity, and by hematoxylin and eosin staining in Ad‑L1 and Ad‑null mice. Compared to Ad‑null control mice, the microtubule‑associated proteins 1A/1B light chain 3 (LC3) particles in the isolated hepatocytes of Ad‑L1 mice were decreased, both under alcohol and non‑alcoholic feeding. The ratio of LC3II/LC3I was significantly decreased, and the level of p62/sequestosome‑1 protein was significantly increased in Ad‑L1 mice compared with Ad‑null mice after alcohol feeding. Levels of LC3II protein were statistically increased in hepatocytes isolated from Ad‑L1 mice with ezetimibe treatment. The increase in LC3II expression was dose dependent. Within the tested range, it reached its highest level at 40 µM. The livers of Ad‑L1 mice represent a more human‑like state for the study of hepatic autophagy. Hepatic expression of human NPC1L1 resulted in an inhibition of autophagy; it may contribute to alcoholic fatty liver disease in humans.
Collapse
Affiliation(s)
- Youlin Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, P.R. China
| | - Pan Yang
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA
| | - Bo Zhang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, P.R. China
| | - Yao Ding
- Department of Oncology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Shun Lei
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing 400038, P.R. China
| | - Yuning Hou
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA
| | - Xiaoqing Guan
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA
| | - Qingwang Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, P.R. China
| |
Collapse
|
3
|
Mercer KE, Bhattacharyya S, Diaz-Rubio ME, Piccolo BD, Pack LM, Sharma N, Chaudhury M, Cleves MA, Chintapalli SV, Shankar K, Ronis MJJ, Yeruva L. Infant Formula Feeding Increases Hepatic Cholesterol 7α Hydroxylase (CYP7A1) Expression and Fecal Bile Acid Loss in Neonatal Piglets. J Nutr 2018; 148:702-711. [PMID: 30053282 PMCID: PMC6857617 DOI: 10.1093/jn/nxy038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/16/2017] [Accepted: 02/09/2018] [Indexed: 12/14/2022] Open
Abstract
Background During the postnatal feeding period, formula-fed infants have higher cholesterol synthesis rates and lower circulating cholesterol concentrations than their breastfed counterparts. Although this disparity has been attributed to the uniformly low dietary cholesterol content of typical infant formulas, little is known of the underlying mechanisms associated with this altered cholesterol metabolism phenotype. Objective We aimed to determine the molecular etiology of diet-associated changes in early-life cholesterol metabolism with the use of a postnatal piglet feeding model. Methods Two-day-old male and female White-Dutch Landrace piglets were fed either sow milk (Sow group) or dairy-based (Milk group; Similac Advance powder) or soy-based (Soy group; Emfamil Prosobee Lipil powder) infant formulas until day 21. In addition to measuring serum cholesterol concentrations, hepatic and intestinal genes involved in enterohepatic circulation of cholesterol and bile acids were analyzed by real-time reverse-transcriptase polymerase chain reaction and Western blot. Bile acid concentrations were measured by liquid chromatography-mass spectrometry in serum, liver, and feces. Results Compared with the Sow group, hepatic cholesterol 7α hydroxylase (CYP7A1) protein expression was 3-fold higher in the Milk group (P < 0.05) and expression was 10-fold higher in the Soy group compared with the Milk group (P < 0.05). Likewise, fecal bile acid concentrations were 3-fold higher in the Soy group compared with the Milk group (P < 0.05). Intestinal mRNA expression of fibroblast factor 19 (Fgf19) was reduced in the Milk and Soy groups, corresponding to 54% and 67% decreases compared with the Sow group. In the Soy group, small heterodimer protein (SHP) protein expression was 30% lower compared with the Sow group (P < 0.05). Conclusions These results indicate that formula feeding leads to increased CYP7A1 protein expression and fecal bile acid loss in neonatal piglets, and this outcome is linked to reduced efficacy in inhibiting CYP7A1 expression through FGF19 and SHP transcriptional repression mechanisms.
Collapse
Affiliation(s)
| | | | | | | | | | - Neha Sharma
- Arkansas Children's Nutrition Center, Little Rock, AR
| | | | | | | | | | - Martin J J Ronis
- Louisiana State University Health Sciences Center, New Orleans, LA
| | - Laxmi Yeruva
- Arkansas Children's Nutrition Center, Little Rock, AR
| |
Collapse
|
4
|
Masko EM, Alfaqih MA, Solomon KR, Barry WT, Newgard CB, Muehlbauer MJ, Valilis NA, Phillips TE, Poulton SH, Freedland AR, Sun S, Dambal SK, Sanders SE, Macias E, Freeman MR, Dewhirst MW, Pizzo SV, Freedland SJ. Evidence for Feedback Regulation Following Cholesterol Lowering Therapy in a Prostate Cancer Xenograft Model. Prostate 2017; 77:446-457. [PMID: 27900797 PMCID: PMC5822711 DOI: 10.1002/pros.23282] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 11/04/2016] [Indexed: 12/17/2022]
Abstract
BACKGROUND Epidemiologic data suggest cholesterol-lowering drugs may prevent the progression of prostate cancer, but not the incidence of the disease. However, the association of combination therapy in cholesterol reduction on prostate or any cancer is unclear. In this study, we compared the effects of the cholesterol lowering drugs simvastatin and ezetimibe alone or in combination on the growth of LAPC-4 prostate cancer in vivo xenografts. METHODS Proliferation assays were conducted by MTS solution and assessed by Student's t-test. 90 male nude mice were placed on a high-cholesterol Western-diet for 7 days then injected subcutaneously with 1 × 105 LAPC-4 cells. Two weeks post-injection, mice were randomized to control, 11 mg/kg/day simvastatin, 30 mg/kg ezetimibe, or the combination and sacrificed 42 days post-randomization. We used a generalized linear model with the predictor variables of treatment, time, and treatment by time (i.e., interaction term) with tumor volume as the outcome variable. Total serum and tumor cholesterol were measured. Tumoral RNA was extracted and cDNA synthesized from 1 ug of total RNA for quantitative real-time PCR. RESULTS Simvastatin directly reduced in vitro prostate cell proliferation in a dose-dependent, cell line-specific manner, but ezetimibe had no effect. In vivo, low continuous dosing of ezetimibe, delivered by food, or simvastatin, delivered via an osmotic pump had no effect on tumor growth compared to control mice. In contrast, dual treatment of simvastatin and ezetimibe accelerated tumor growth. Ezetimibe significantly lowered serum cholesterol by 15%, while simvastatin had no effect. Ezetimibe treatment resulted in higher tumor cholesterol. A sixfold induction of low density lipoprotein receptor mRNA was observed in ezetimibe and the combination with simvastatin versus control tumors. CONCLUSIONS Systemic cholesterol lowering by ezetimibe did not slow tumor growth, nor did the cholesterol independent effects of simvastatin and the combined treatment increased tumor growth. Despite lower serum cholesterol, tumors from ezetimibe treated mice had higher levels of cholesterol. This study suggests that induction of low density lipoprotein receptor is a possible mechanism of resistance that prostate tumors use to counteract the therapeutic effects of lowering serum cholesterol. Prostate 77:446-457, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Elizabeth M. Masko
- Division of Urologic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Mahmoud A. Alfaqih
- Division of Urologic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Keith R. Solomon
- Department of Orthopedic Surgery, Harvard Medical School, Boston, Massachusetts
| | - William T. Barry
- Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina
| | - Christopher B. Newgard
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, North Carolina
| | - Michael J. Muehlbauer
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, North Carolina
| | - Nikolaos A. Valilis
- Division of Urologic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Tameika E. Phillips
- Division of Urologic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Susan H. Poulton
- Division of Urologic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Alexis R. Freedland
- Division of Urology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California
| | - Stephanie Sun
- Department of Surgery, Durham Veterans Administration Hospital, Durham, North Carolina
| | - Shweta K. Dambal
- Division of Urology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California
| | - Sergio E. Sanders
- Division of Urology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California
| | - Everardo Macias
- Division of Urologic Surgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina
- Division of Urology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California
| | - Michael R. Freeman
- Division of Urology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California
| | - Mark W. Dewhirst
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - Salvatore V. Pizzo
- Department of Pathology, Duke University Medical Center, Durham, North Carolina
| | - Stephen J. Freedland
- Division of Urology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California
- Department of Surgery, Durham Veterans Administration Hospital, Durham, North Carolina
- Correspondence to: Dr. Stephen Freedland, Division of Urology, Department of Surgery, Cedars Sinai Medical Center, 8635 West 3rd Street Suite 1070W, Los Angeles, CA 90048.
| |
Collapse
|
5
|
Pelton K, Coticchia CM, Curatolo AS, Schaffner CP, Zurakowski D, Solomon KR, Moses MA. Hypercholesterolemia induces angiogenesis and accelerates growth of breast tumors in vivo. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 184:2099-110. [PMID: 24952430 DOI: 10.1016/j.ajpath.2014.03.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 03/20/2014] [Accepted: 03/26/2014] [Indexed: 12/19/2022]
Abstract
Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo.
Collapse
Affiliation(s)
- Kristine Pelton
- Department of Urology, Boston Children's Hospital, Boston, Massachusetts
| | - Christine M Coticchia
- The Program in Vascular Biology, Boston Children's Hospital, Boston, Massachusetts; Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts
| | - Adam S Curatolo
- The Program in Vascular Biology, Boston Children's Hospital, Boston, Massachusetts
| | - Carl P Schaffner
- Department of Microbiology and Biochemistry, Waksman Institute, Rutgers, the State University of New Jersey, New Brunswick, New Jersey
| | - David Zurakowski
- Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts; Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - Keith R Solomon
- Department of Urology, Boston Children's Hospital, Boston, Massachusetts; Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts; Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.
| | - Marsha A Moses
- The Program in Vascular Biology, Boston Children's Hospital, Boston, Massachusetts; Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts
| |
Collapse
|
6
|
Naruse R, Hori KI, Terasawa T, Hara K, Suetsugu M, Takebayashi K, Morita K, Aso Y, Inukai T. Alterations of plant sterols, lathosterol, oxidative stress and inflammatory markers after the combination therapy of ezetimibe and statin drugs in type 2 diabetic patients. Obes Res Clin Pract 2015; 9:67-74. [DOI: 10.1016/j.orcp.2014.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 02/09/2014] [Accepted: 02/21/2014] [Indexed: 11/29/2022]
|
7
|
Xie P, Zhu H, Jia L, Ma Y, Tang W, Wang Y, Xue B, Shi H, Yu L. Genetic demonstration of intestinal NPC1L1 as a major determinant of hepatic cholesterol and blood atherogenic lipoprotein levels. Atherosclerosis 2014; 237:609-17. [PMID: 25463095 DOI: 10.1016/j.atherosclerosis.2014.09.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 09/08/2014] [Accepted: 09/17/2014] [Indexed: 12/21/2022]
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.
Collapse
Affiliation(s)
- Ping Xie
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Department of Biochemistry, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
| | - Hongling Zhu
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Lin Jia
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Department of Biochemistry, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Yinyan Ma
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Department of Biochemistry, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Weiqing Tang
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Youlin Wang
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Bingzhong Xue
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Hang Shi
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Liqing Yu
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Department of Biochemistry, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA; Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA.
| |
Collapse
|
8
|
Fu ZD, Cui JY, Klaassen CD. Atorvastatin induces bile acid-synthetic enzyme Cyp7a1 by suppressing FXR signaling in both liver and intestine in mice. J Lipid Res 2014; 55:2576-86. [PMID: 25278499 DOI: 10.1194/jlr.m053124] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Statins are effective cholesterol-lowering drugs to treat CVDs. Bile acids (BAs), the end products of cholesterol metabolism in the liver, are important nutrient and energy regulators. The present study aims to investigate how statins affect BA homeostasis in the enterohepatic circulation. Male C57BL/6 mice were treated with atorvastatin (100 mg/kg/day po) for 1 week, followed by BA profiling by ultra-performance LC-MS/MS. Atorvastatin decreased BA pool size, mainly due to less BA in the intestine. Surprisingly, atorvastatin did not alter total BAs in the serum or liver. Atorvastatin increased the ratio of 12α-OH/non12α-OH BAs. Atorvastatin increased the mRNAs of the BA-synthetic enzymes cholesterol 7α-hydroxylase (Cyp7a1) (over 10-fold) and cytochrome P450 27a1, the BA uptake transporters Na⁺/taurocholate cotransporting polypeptide and organic anion transporting polypeptide 1b2, and the efflux transporter multidrug resistance-associated protein 2 in the liver. Noticeably, atorvastatin suppressed the expression of BA nuclear receptor farnesoid X receptor (FXR) target genes, namely small heterodimer partner (liver) and fibroblast growth factor 15 (ileum). Furthermore, atorvastatin increased the mRNAs of the organic cation uptake transporter 1 and cholesterol efflux transporters Abcg5 and Abcg8 in the liver. The increased expression of BA-synthetic enzymes and BA transporters appear to be a compensatory response to maintain BA homeostasis after atorvastatin treatment. The Cyp7a1 induction by atorvastatin appears to be due to suppressed FXR signaling in both the liver and intestine.
Collapse
Affiliation(s)
- Zidong Donna Fu
- Departments of Pharmacology, Toxicology, and Therapeutics University of Kansas Medical Center, Kansas City, KS 66160 Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin, Heilongjiang Province, People's Republic of China 150081
| | - Julia Yue Cui
- Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160
| | - Curtis D Klaassen
- Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160
| |
Collapse
|
9
|
Bonamassa B, Moschetta A. Atherosclerosis: lessons from LXR and the intestine. Trends Endocrinol Metab 2013; 24:120-8. [PMID: 23158108 DOI: 10.1016/j.tem.2012.10.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/12/2012] [Accepted: 10/18/2012] [Indexed: 12/17/2022]
Abstract
Modulation of the cholesterol-sensing liver X receptors (LXRs) and their downstream targets has emerged as promising therapeutic avenues in atherosclerosis. The intestine is important for its unique capabilities to act as a gatekeeper for cholesterol absorption and to participate in the process of cholesterol elimination in the feces and reverse cholesterol transport (RCT). Pharmacological and genetic intestine-specific LXR activation have been shown to protect against atherosclerosis. In this review we discuss the LXR-targeted molecular players in the enterocytes as well as the intestine-driven pathways contributing to cholesterol homeostasis with therapeutic potential as targets in the prevention and treatment of atherosclerosis..
Collapse
Affiliation(s)
- Barbara Bonamassa
- Laboratory of Lipid Metabolism and Cancer, Department of Translational Pharmacology, Consorzio Mario Negri Sud, Via Nazionale 8/A, 66030 Santa Maria Imbaro (CH), Italy
| | | |
Collapse
|
10
|
Jia L, Betters JL, Yu L. Niemann-pick C1-like 1 (NPC1L1) protein in intestinal and hepatic cholesterol transport. Annu Rev Physiol 2011; 73:239-59. [PMID: 20809793 DOI: 10.1146/annurev-physiol-012110-142233] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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 counter-balances 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 of metabolic diseases.
Collapse
Affiliation(s)
- Lin Jia
- Section on Lipid Sciences, Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1040, USA
| | | | | |
Collapse
|
11
|
Tremblay AJ, Lamarche B, Lemelin V, Hoos L, Benjannet S, Seidah NG, Davis HR, Couture P. Atorvastatin increases intestinal expression of NPC1L1 in hyperlipidemic men. J Lipid Res 2010; 52:558-65. [PMID: 21123766 DOI: 10.1194/jlr.m011080] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Inhibition of cholesterol synthesis by 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoAR) inhibitors has been associated with an increase in intestinal cholesterol absorption. This study examined how HMG-CoAR inhibition by atorvastatin modulates expression of key genes involved in intestinal cholesterol metabolism. A crossover study was conducted in which 22 hyperlipidemic men received atorvastatin, 40 mg/day, or placebo, each for 12 weeks. Gene expression was assessed by real-time PCR using duodenal biopsy samples obtained at the end of each phase of treatment. Treatment with atorvastatin was associated with a 76% reduction in lathosterol and significant increases in sitosterol (70%). Atorvastatin significantly increased intestinal mRNA levels of HMG-CoAR (59%), LDL receptor (LDLR) (52%), PCSK9 (187%), SREBP-2 (44%), and HNF-4α (13%). Furthermore, atorvastatin significantly increased intestinal mRNA levels of NPC1L1 by 19% and decreased mRNA levels of both ABCG5 and ABCG8 by 14%. Positive correlations were observed between changes in SREBP-2 and HNF-4α expression and concurrent changes in the intestinal mRNA levels of HMG-CoAR, LDLR, and NPC1L1. These results indicate that HMG-CoAR inhibition with atorvastatin stimulates the intestinal expression of NPC1L1, LDLR, and PCSK9; increases cholesterol absorption; and reduces expression of ABCG5/8; these effects are most likely mediated by upregulation of the transcription factors SREBP-2 and HNF-4α.
Collapse
Affiliation(s)
- André J Tremblay
- Lipid Research Centre, Laval University, Quebec City, Quebec, Canada
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Rodrigues AC. Efflux and uptake transporters as determinants of statin response. Expert Opin Drug Metab Toxicol 2010; 6:621-32. [PMID: 20367534 DOI: 10.1517/17425251003713519] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
IMPORTANCE OF THE FIELD The important role of drug transporters in drug absorption and disposition has been well documented. Statins are subjected to active transport of membrane proteins of the superfamilies ATP-binding cassette and solute carrier, and there is limited understanding of the mechanisms by which differences in transporter expression and activity contributes to variability of pharmacokinetics (PKs)/pharmacodynamics (PDs) of statins. AREAS COVERED IN THIS REVIEW This review aims to discuss the roles of drug transporters in the PKs and PDs of statins, and in drug interactions with statins. WHAT THE READER WILL GAIN A comprehensive summary of the literature on this subject including in vitro and in vivo observations. TAKE HOME MESSAGE In vivo and in vitro studies have shown that efflux and uptake transporters modulate the PKs/PDs of statins. Until now organic anion transporting polypeptides (OATP)1B1 variants have been considered major factors in limiting the uptake of statins and increasing statin exposure, and, consequently, increasing risk of myopathy. Further studies in pharmacogenetics and in vitro models to assess statin disposition and toxicity are required to understand the contribution of others transporters, such as multidrug resistance-associated protein (MRP)1, MRP2, breast cancer resistance protein, OATP2B1, OAT1B3 and OATP1A2, in interindividual variability to statins efficacy and safety.
Collapse
Affiliation(s)
- Alice C Rodrigues
- University of Sao Paulo, Department of Clinical and Toxicological Analysis, Faculty of Pharmaceutical Sciences, Av. Prof. Lineu Prestes, 580, bl17s, Sao Paulo 05508-000, SP, Brazil.
| |
Collapse
|
13
|
Jia L, Ma Y, Liu G, Yu L. Dietary cholesterol reverses resistance to diet-induced weight gain in mice lacking Niemann-Pick C1-Like 1. J Lipid Res 2010; 51:3024-33. [PMID: 20601625 DOI: 10.1194/jlr.m008599] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Niemann-Pick C1-Like 1 (NPC1L1) mediates intestinal cholesterol absorption. NPC1L1 knockout (L1-KO) mice were recently shown to be resistant to high-fat diet (HFD)-induced obesity in one study, which was contrary to several other studies. Careful comparison of dietary compositions in these studies implies a potential role of dietary cholesterol in regulating weight gain. To examine this potential, wild-type (WT) and L1-KO mice were fed one of three sets of diets for various durations: (1) a HFD without added cholesterol for 5 weeks; (2) a high-carbohydrate diet with or without added cholesterol for 5 weeks; or (3) a synthetic HFD with or without added cholesterol for 18 weeks. We found that L1-KO mice were protected against diet-induced weight gain only on a diet without added cholesterol but not on a diet containing 0.16% or 0.2% (w/w) cholesterol, an amount similar to a typical Western diet, regardless of the major energy source of the diet. Food intake and intestinal fat absorption were similar between the two genotypes. Intestinal cholesterol absorption was blocked, and fecal cholesterol excretion increased in L1-KO mice. Under all diets, L1-KO mice were protected from hepatosteatosis. In conclusion, increasing dietary cholesterol restores diet-induced weight gain in mice deficient in NPC1L1-dependent cholesterol absorption.
Collapse
Affiliation(s)
- Lin Jia
- Department of Pathology and Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | | | | | | |
Collapse
|
14
|
Betters JL, Yu L. NPC1L1 and cholesterol transport. FEBS Lett 2010; 584:2740-7. [PMID: 20307540 PMCID: PMC2909875 DOI: 10.1016/j.febslet.2010.03.030] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 03/15/2010] [Accepted: 03/16/2010] [Indexed: 12/18/2022]
Abstract
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.
Collapse
Affiliation(s)
- Jenna L. Betters
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| | - Liqing Yu
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| |
Collapse
|
15
|
Abstract
Dysregulation of cholesterol balance contributes significantly to atherosclerotic cardiovascular disease (ASCVD), the leading cause of death in the United States. The intestine has the unique capability to act as a gatekeeper for entry of cholesterol into the body, and inhibition of intestinal cholesterol absorption is now widely regarded as an attractive non-statin therapeutic strategy for ASCVD prevention. In this chapter we discuss the current state of knowledge regarding sterol transport across the intestinal brush border membrane. The purpose of this work is to summarize substantial progress made in the last decade in regards to protein-mediated sterol trafficking, and to discuss this in the context of human disease.
Collapse
Affiliation(s)
| | - Liqing Yu
- Address correspondence to: Liqing Yu, M.D., Ph.D., Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157-1040, Tel: 336-716-0920, Fax: 336-716-6279,
| |
Collapse
|
16
|
Transporters as drug targets: discovery and development of NPC1L1 inhibitors. Clin Pharmacol Ther 2009; 87:117-21. [PMID: 19907422 DOI: 10.1038/clpt.2009.209] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The potent cholesterol absorption inhibitor ezetimibe was developed as a first-in-class drug for treating hypercholesterolemia even before its molecular target, Niemann-Pick C1-like 1 (NPC1L1), had been identified. The NPC1L1 protein mediates sterol transport across the enterocyte brush border membrane and is essential for intestinal cholesterol absorption, a major pathway controlling whole-body cholesterol homeostasis. An elucidation of the mechanism underlying NPC1L1-dependent cholesterol absorption would greatly facilitate the discovery and development of new cholesterol-lowering agents for treating hypercholesterolemia and other cholesterol-related metabolic disorders.
Collapse
|
17
|
Scheri RC, Lee J, Barofsky DF, Curtis LR. Chlordecone increased subcellular distribution of scavenger receptor class B type II to murine hepatic microsomes without altering cytosolic cholesterol binding proteins. Toxicol Lett 2009; 191:20-5. [PMID: 19666090 DOI: 10.1016/j.toxlet.2009.07.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 10/20/2022]
Abstract
Pretreatment of male C57BL/6 mice with low doses of the persistent organochlorine pesticide, chlordecone (CD), stimulated biliary excretion of exogenous cholesterol (CH) up to 3-fold. Increased biliary excretion occurred without changes in hepatic ATP-binding cassette transporter G8 (ABCG8) of the bile canaliculus or scavenger receptor class B type I (SR-BI) of the sinusoidal surface. A variety of tissues express scavenger receptor class B type II (SR-BII) and this protein was identified as a splice variant from the SR-BI gene. Although the function of SR-BII has not been elucidated it may play a role in CH homeostasis and trafficking distinctly different than SR-BI. Western blotting demonstrated that a single dose of CD promoted subcellular distribution of SR-BII to murine hepatic microsomes about 2.2-fold when compared to controls without effect on liver crude membrane SR-BII content. This was consistent with increased vesicular CH trafficking. Relative quantification of hepatic cytosolic proteins in a fraction that sequestered [(14)C]CH by mass spectrometry (MS) indicated no role for cytosolic CH binding proteins in CD altered CH homeostasis. Western blotting verified no effect of CD on liver fatty acid-binding protein (L-FABP) in cytosol. MS detected a statistically significant increase in myosin-9, which was also consistent with increased vesicular trafficking.
Collapse
Affiliation(s)
- Richard C Scheri
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | | | | | | |
Collapse
|
18
|
Brown JM, Yu L. Opposing Gatekeepers of Apical Sterol Transport: Niemann-Pick C1-Like 1 (NPC1L1) and ATP-Binding Cassette Transporters G5 and G8 (ABCG5/ABCG8). IMMUNOLOGY, ENDOCRINE & METABOLIC AGENTS IN MEDICINAL CHEMISTRY 2009; 9:18-29. [PMID: 20174593 PMCID: PMC2824437 DOI: 10.2174/187152209788009797] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholesterol is essential for the growth and function of all mammalian cells, but abnormally elevated levels of circulating low-density lipoprotein cholesterol (LDL-C) are a major risk factor for the development of atherosclerotic cardiovascular disease (ASCVD). For many years, statin drugs have been used to effectively lower LDL-C, but ASCVD still persists in most of the world. Hence, additional LDL-C lowering is now recommended, and the search for therapeutic strategies that work in synergy with statins has now begun. Intestinal absorption and biliary excretion of cholesterol represent two major pathways and continue to show promise as druggable processes. Importantly, both of these complex physiological pathways are tightly regulated by key proteins located at the apical surface of the small intestine and the liver. One of these proteins, the target of ezetimibe Niemann-Pick C1-Like 1 (NPC1L1), was recently identified to be essential for intestinal cholesterol absorption and protect against excessive biliary sterol loss. In direct opposition of NPC1L1, the heterodimer of ATP-binding cassette transporters G5 and G8 (ABCG5/ABCG8) has been shown to be critical for promoting biliary cholesterol secretion in the liver, and has also been proposed to play a direct role in intestinal disposal of sterols. The purpose of this review is to summarize the current state of knowledge regarding the function of these opposing apical cholesterol transporters, and provide a framework for future studies examining these proteins.
Collapse
Affiliation(s)
- J. Mark Brown
- Department of Pathology-Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| | - Liqing Yu
- Department of Pathology-Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| |
Collapse
|
19
|
Temel RE, Brown JM, Ma Y, Tang W, Rudel LL, Ioannou YA, Davies JP, Yu L. Diosgenin stimulation of fecal cholesterol excretion in mice is not NPC1L1 dependent. J Lipid Res 2009; 50:915-23. [PMID: 19141868 DOI: 10.1194/jlr.m800631-jlr200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
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 (mumol/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.
Collapse
Affiliation(s)
- Ryan E Temel
- Department of Pathology, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
PURPOSE OF REVIEW Intestinal absorption and biliary excretion of cholesterol represent two major pathways by which the body regulates cholesterol homeostasis. Niemann-Pick C1-like 1 (NPC1L1) is a polytopic transmembrane protein containing a sterol-sensing domain of unknown function. In 2004, NPC1L1 was identified to be essential for intestinal cholesterol absorption, a process that is sensitive to a cholesterol absorption inhibitor ezetimibe. This review summarizes recent studies on NPC1L1 function and proposes a model for NPC1L1-dependent cholesterol uptake. RECENT FINDINGS Cell culture experiments have shown that NPC1L1 mediates cellular uptake of various sterols but seems to have lower affinity to plant sterols than cholesterol. Transgenic animal studies have demonstrated that hepatic NPC1L1 has the potential to regulate biliary cholesterol excretion. Cholesterol and many transcriptional factors appear to regulate NPC1L1 gene expression. NPC1L1 protein is enriched in the apical membrane of polarized cells and its intracellular itineraries are clearly regulated by cholesterol availability. Evidence suggests cholesterol-regulated clathrin-mediated endocytosis is likely the cellular basis for NPC1L1-dependent cholesterol uptake, which may reconcile disagreement regarding NPC1L1 subcellular localization. SUMMARY NPC1L1 may have evolved at two sites (apical membrane of enterocytes and canalicular membrane of hepatocytes) to mediate cholesterol uptake through a clathrin-mediated endocytic process, protecting the body against fecal and biliary loss of cholesterol.
Collapse
Affiliation(s)
- Liqing Yu
- Department of Pathology Section on Lipid Sciences, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157-1040, USA.
| |
Collapse
|