{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T15:20:54Z","timestamp":1773674454332,"version":"3.50.1"},"reference-count":38,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2016,7,13]],"date-time":"2016-07-13T00:00:00Z","timestamp":1468368000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Science and Technology","award":["MOST 103-2320-B-038-044"],"award-info":[{"award-number":["MOST 103-2320-B-038-044"]}]},{"name":"Ministry of Science and Technology","award":["103-2815-C-038-024-B"],"award-info":[{"award-number":["103-2815-C-038-024-B"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>In chronic liver diseases, regardless of their etiology, the development of fibrosis is the first step toward the progression to cirrhosis, portal hypertension, and hepatocellular carcinoma. Hepatic stellate cells (HSCs) are the main profibrogenic cells that promote the pathogenesis of liver fibrosis, and so it is important to identify the molecules that regulate HSCs activation and liver fibrosis. Niemann-Pick type C2 (NPC2) protein plays an important role in the regulation of intracellular cholesterol homeostasis by directly binding with free cholesterol. However, the roles of NPC2 in HSCs activation and liver fibrosis have not been explored in detail. Since a high-cholesterol diet exacerbates liver fibrosis progression in both rodents and humans, we propose that the expression of NPC2 affects free cholesterol metabolism and regulates HSCs activation. In this study, we found that NPC2 is decreased in both thioacetamide- and carbon tetrachloride-induced liver fibrosis tissues. In addition, NPC2 is expressed in quiescent HSCs, but its activation status is down-regulated. Knockdown of NPC2 in HSC-T6 cells resulted in marked increases in transforming growth factor-\u03b21 (TGF-\u03b21)-induced collagen type 1 \u03b11 (Col1a1), \u03b1-smooth muscle actin (\u03b1-SMA) expression, and Smad2 phosphorylation. In contrast, NPC2 overexpression decreased TGF-\u03b21-induced HSCs activation. We further demonstrated that NPC2 deficiency significantly increased the accumulation of free cholesterol in HSCs, increasing Col1a1 and \u03b1-SMA expression and activating Smad2, and leading to sensitization of HSCs to TGF-\u03b21 activation. In contrast, overexpression of NPC2 decreased U18666A-induced free cholesterol accumulation and inhibited the subsequent HSCs activation. In conclusion, our study has demonstrated that NPC2 plays an important role in HSCs activation by regulating the accumulation of free cholesterol. NPC2 overexpression may thus represent a new treatment strategy for liver fibrosis.<\/jats:p>","DOI":"10.3390\/ijms17071122","type":"journal-article","created":{"date-parts":[[2016,7,13]],"date-time":"2016-07-13T09:48:45Z","timestamp":1468403325000},"page":"1122","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Niemann-Pick Type C2 Protein Mediates Hepatic Stellate Cells Activation by Regulating Free Cholesterol Accumulation"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0327-0738","authenticated-orcid":false,"given":"Yuh-Ching","family":"Twu","sequence":"first","affiliation":[{"name":"Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang-Ming University, 112 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tzong-Shyuan","family":"Lee","sequence":"additional","affiliation":[{"name":"Department &amp; Institute of Physiology, National Yang-Ming University, 112 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yun-Lian","family":"Lin","sequence":"additional","affiliation":[{"name":"College of Biopharmaceutical and Food Sciences, China Medical University, 404 Taichung, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shih-Ming","family":"Hsu","sequence":"additional","affiliation":[{"name":"Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, 112 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuan-Hsi","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, 110 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chia-Yu","family":"Liao","sequence":"additional","affiliation":[{"name":"School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, 110 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chung-Kwe","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of International Medicine, Taipei City Hospital Ranai Branch, 106 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0889-2747","authenticated-orcid":false,"given":"Yu-Chih","family":"Liang","sequence":"additional","affiliation":[{"name":"School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, 110 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9836-1503","authenticated-orcid":false,"given":"Yi-Jen","family":"Liao","sequence":"additional","affiliation":[{"name":"School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, 110 Taipei, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,7,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1016\/S0140-6736(08)60383-9","article-title":"Liver cirrhosis","volume":"371","author":"Schuppan","year":"2008","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1172\/JCI24282","article-title":"Liver fibrosis","volume":"115","author":"Bataller","year":"2005","journal-title":"J. Clin. Investig."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"S38","DOI":"10.1016\/S0168-8278(02)00429-4","article-title":"Liver fibrosis\u2014From bench to bedside","volume":"38","author":"Friedman","year":"2003","journal-title":"J. Hepatol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"876","DOI":"10.1016\/j.bbadis.2012.11.002","article-title":"Extracellular matrix degradation in liver fibrosis: Biochemistry and regulation","volume":"1832","author":"Iredale","year":"2013","journal-title":"Biochim. Biophys. Acta"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1172\/JCI30542","article-title":"Models of liver fibrosis: Exploring the dynamic nature of inflammation and repair in a solid organ","volume":"117","author":"Iredale","year":"2007","journal-title":"J. Clin. Investig."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1146\/annurev-pathol-011110-130246","article-title":"Pathogenesis of liver fibrosis","volume":"6","author":"Friedman","year":"2011","journal-title":"Annu. Rev. Pathol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1016\/j.bpg.2011.02.006","article-title":"Liver fibrogenic cells","volume":"25","author":"Forbes","year":"2011","journal-title":"Best Pract. Res. Clin. Gastroenterol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1016\/j.tox.2008.06.013","article-title":"Hepatic fibrosis\u2014Overview","volume":"254","author":"Friedman","year":"2008","journal-title":"Toxicology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1655","DOI":"10.1053\/j.gastro.2008.03.003","article-title":"Mechanisms of hepatic fibrogenesis","volume":"134","author":"Friedman","year":"2008","journal-title":"Gastroenterology"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"530","DOI":"10.1038\/nrgastro.2012.114","article-title":"Hepatic stem cells and transforming growth factor \u03b2 in hepatocellular carcinoma","volume":"9","author":"Majumdar","year":"2012","journal-title":"Nat. Rev. Gastroenterol. Hepatol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/j.bpg.2011.02.005","article-title":"Mechanisms of hepatic fibrogenesis","volume":"25","author":"Lee","year":"2011","journal-title":"Best Pract. Res. Clin. Gastroenterol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1136\/gut.2005.088690","article-title":"Emerging insights into transforming growth factor \u03b2 Smad signal in hepatic fibrogenesis","volume":"56","author":"Inagaki","year":"2007","journal-title":"Gut"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"G709","DOI":"10.1152\/ajpgi.00451.2010","article-title":"Therapeutic targets in liver fibrosis","volume":"300","author":"Fallowfield","year":"2011","journal-title":"Am. J. Physiol. Gastrointest. Liver Physiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1022","DOI":"10.1053\/jhep.2002.32673","article-title":"Dose-dependent inhibition of hepatic fibrosis in mice by a TGF-\u03b2 soluble receptor: Implications for antifibrotic therapy","volume":"35","author":"Yata","year":"2002","journal-title":"Hepatology"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.bbalip.2004.08.007","article-title":"Structure and function of the NPC2 protein","volume":"1685","author":"Vanier","year":"2004","journal-title":"Biochim. Biophys. Acta"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2298","DOI":"10.1126\/science.290.5500.2298","article-title":"Identification of HE1 as the second gene of Niemann-Pick C disease","volume":"290","author":"Naureckiene","year":"2000","journal-title":"Science"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1016\/j.bbalip.2009.02.001","article-title":"Niemann-Pick C2 (NPC2) and intracellular cholesterol trafficking","volume":"1791","author":"Storch","year":"2009","journal-title":"Biochim. Biophys. Acta"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2518","DOI":"10.1073\/pnas.0530027100","article-title":"The integrity of a cholesterol-binding pocket in Niemann-Pick C2 protein is necessary to control lysosome cholesterol levels","volume":"100","author":"Ko","year":"2003","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"5886","DOI":"10.1073\/pnas.0308456101","article-title":"Genetic evidence for nonredundant functional cooperativity between NPC1 and NPC2 in lipid transport","volume":"101","author":"Sleat","year":"2004","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.bbalip.2004.08.009","article-title":"Lipid and cholesterol trafficking in NPC","volume":"1685","author":"Mukherjee","year":"2004","journal-title":"Biochim. Biophys. Acta"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1341","DOI":"10.1002\/ijc.29507","article-title":"Niemann-Pick type C2 protein regulates liver cancer progression via modulating ERK1\/2 pathway: Clinicopathological correlations and therapeutical implications","volume":"137","author":"Liao","year":"2015","journal-title":"Int. J. Cancer"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Liao, Y.J., Lin, M.W., Yen, C.H., Lin, Y.T., Wang, C.K., Huang, S.F., Chen, K.H., Yang, C.P., Chen, T.L., and Hou, M.F. (2013). Characterization of Niemann-Pick type C2 protein expression in multiple cancers using a novel NPC2 monoclonal antibody. PLoS ONE, 8.","DOI":"10.1371\/journal.pone.0077586"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1002\/hep.22941","article-title":"Association between dietary nutrient composition and the incidence of cirrhosis or liver cancer in the united states population","volume":"50","author":"Ioannou","year":"2009","journal-title":"Hepatology"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.jhep.2007.02.013","article-title":"Statins in non-alcoholic fatty liver disease and chronically elevated liver enzymes: A histopathological follow-up study","volume":"47","author":"Ekstedt","year":"2007","journal-title":"J. Hepatol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1053\/j.gastro.2011.09.049","article-title":"A high-cholesterol diet exacerbates liver fibrosis in mice via accumulation of free cholesterol in hepatic stellate cells","volume":"142","author":"Teratani","year":"2012","journal-title":"Gastroenterology"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"938","DOI":"10.1053\/j.gastro.2011.12.044","article-title":"Autophagy releases lipid that promotes fibrogenesis by activated hepatic stellate cells in mice and in human tissues","volume":"142","author":"Rozenfeld","year":"2012","journal-title":"Gastroenterology"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.jhep.2014.03.018","article-title":"Acyl-CoA:Cholesterol acyltransferase 1 mediates liver fibrosis by regulating free cholesterol accumulation in hepatic stellate cells","volume":"61","author":"Tomita","year":"2014","journal-title":"J. Hepatol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"154","DOI":"10.1002\/hep.26604","article-title":"Free cholesterol accumulation in hepatic stellate cells: Mechanism of liver fibrosis aggravation in nonalcoholic steatohepatitis in mice","volume":"59","author":"Tomita","year":"2014","journal-title":"Hepatology"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1095\/biolreprod54.4.847","article-title":"Molecular cloning and characterization of HE1, a major secretory protein of the human epididymis","volume":"54","author":"Kirchhoff","year":"1996","journal-title":"Biol. Reprod."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"612","DOI":"10.1038\/nature04399","article-title":"Role of cholesterol and lipid organization in disease","volume":"438","author":"Maxfield","year":"2005","journal-title":"Nature"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1243","DOI":"10.1038\/nm1102-1243","article-title":"The liver X receptor gene team: Potential new players in atherosclerosis","volume":"8","author":"Repa","year":"2002","journal-title":"Nat. Med."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1038\/nrm2336","article-title":"Cellular cholesterol trafficking and compartmentalization","volume":"9","author":"Ikonen","year":"2008","journal-title":"Nat. Rev. Mol. Cell Biol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"657","DOI":"10.1038\/35089558","article-title":"Multidrug permeases and subcellular cholesterol transport","volume":"2","author":"Ioannou","year":"2001","journal-title":"Nat. Rev. Mol. Cell Biol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"208","DOI":"10.1016\/j.cmet.2009.07.003","article-title":"Nogo-B receptor stabilizes Niemann-Pick Type C2 protein and regulates intracellular cholesterol trafficking","volume":"10","author":"Harrison","year":"2009","journal-title":"Cell Metab."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.cmet.2006.07.006","article-title":"Mitochondrial free cholesterol loading sensitizes to TNF- and FAS-mediated steatohepatitis","volume":"4","author":"Mari","year":"2006","journal-title":"Cell Metab."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1006\/taap.2001.9304","article-title":"The role of tumor necrosis factor-\u03b1 in liver toxicity, inflammation, and fibrosis induced by carbon tetrachloride","volume":"177","author":"Simeonova","year":"2001","journal-title":"Toxicol. Appl. Pharmacol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"36688","DOI":"10.1074\/jbc.M304011200","article-title":"Tumor necrosis factor \u03b1-dependent up-regulation of LRH-1 and MRP3(ABCC3) reduces liver injury in obstructive cholestasis","volume":"278","author":"Bohan","year":"2003","journal-title":"J. Biol. Chem."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"704","DOI":"10.1111\/j.1582-4934.2007.00060.x","article-title":"Immortal hepatic stellate cell lines: Useful tools to study hepatic stellate cell biology and function?","volume":"11","author":"Herrmann","year":"2007","journal-title":"J. Cell. Mol. Med."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/17\/7\/1122\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:26:04Z","timestamp":1760210764000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/17\/7\/1122"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,7,13]]},"references-count":38,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2016,7]]}},"alternative-id":["ijms17071122"],"URL":"https:\/\/doi.org\/10.3390\/ijms17071122","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,7,13]]}}}