Wen-Xing Ding, PhD
William Warner Abercrombie Professor
PhD, National University of Singapore, Singapore, 2002
Postdoctoral Fellowship, University of Pittsburgh, 2005
Autophagy and Apoptosis in liver injury and cancer therapy; Redox Signaling and Mitochondrial damage; Mitophagy
1. Mechanisms of autophagy in alcoholic liver disease and pancreatitis.
Macroautophagy (referred to as autophagy hereafter) is a major intracellular degradation system that is responsible for the degradation of long-lived proteins and other cellular contents. It is usually activated in response to adverse environment, such as the deprivation of nutrients or growth factors. Autophagy plays a role in development, in defending against microbial infections, in regulating lipid homeostasis and organelles turnover such as mitochondria, and in the pathogenesis of a number of diseases including cancer. In October 2016, The Noble Prize for Physiology and Medicine was given to Professor Yoshinori Ohsumi for his discovery of the mechanisms that regulate autophagy.
Alcohol abuse is a major cause of liver injury. The pathology of alcoholic liver disease develops over a prolonged period. However, the cellular defense mechanisms against the detrimental effects of alcohol are not well understood. We recently demonstrated that autophagy is activated and protects against acute ethanol-induced liver injury and steatosis in mice. Specifically, we found that ethanol-induced autophagy may selectively remove damaged mitochondria (mitophagy) and lipid droplets (lipophagy). However, chronic alcohol consumption impairs hepatic lysosomal biogenesis results in insufficient autophagy, a novel previously unappreciated autophagic flux scenario.
Ethanol induces mitophagy in mouse hepatocytes. (A) Confocal microscopy images of ethanol-treated mouse hepatocytes (green: GFP-LC3; Red: Mitotracker red). (B) Electron microscopy images of ethanol-treated mouse hepatocytes. Be noted double membrane enveloped mitochondria.
Ding et al., Gastroenterology 2010; Ding et al., EBM 2011; Ni et al Pharm Res. 2012; Ni et al AJP 2013; Williams et al., WJG 2014, Li Y et al., BioMedical Research International 2014; Williams et al., AJP 2015; Wang et al, Oncotarget 2016; Wang et al, ACER, 2016, Nagy et al Gastroenterology 2016, Wang & Ding, Gut 2016
Chronic alcohol impairs TFEB-mediated lysosomal biogenesis leading to alcohol-induced liver injury.
Chronic alcohol activates MTOR that leads to the phosphorylation of TFEB and inactivation of TFEB. Overexpression of TFEB increases lysosomal and mitochondrial biogenesis and protects against alcohol-induced steatosis and liver injury.
Chao X et al Gastroenterology 2018, Chao X et al, Autophagy 2018.
Using the recently established chronic plus acute binge alcohol (Gao-binge) model, we found that Gao-binge alcohol inhibits TFEB, a master regulator and transcription factor for the gene expression of lysosomal biogenesis and autophagy-related genes, resulting in insufficient autophagy in the liver. Moreover, we also found that TFEB-mediated lysosomal biogenesis also plays a critical role in alcohol-induced pancreatitis. We have generated several genetic mouse models (liver-specific or acinar cell specific TFEB and TFE3 knockout mice) and are currently investigating the role of TFEB in alcohol-induced liver injury and pancreatitis.
2. Mechanisms of mitochondria autophagy (mitophagy) and mitochondria dynamics and biogenesis
Mitochondria are dynamic organelles that are responsible for creating more than 90% of the energy needed by the body. Mitochondria are also the central-regulators for apoptosis and the major sources for the production of reactive oxygen species. Many environmental toxicants and chemotherapeutic drugs can damage mitochondria. Damaged mitochondria have been involved in cell death, ischemia and reperfusion injury, aging and many neurodegenerative conditions such as Alzheimer's and Parkinson's disease. It is thus important to eliminate damaged and aged mitochondria to protect the cells against its detrimental effects on the cells. It is now known that autophagy plays an important role to remove these damaged mitochondria, a process, called mitophagy. However, it is not known how damaged mitochondria are eventually recognized by the autophagosomes in mammalian cells although it has recently been reported that Atg32 is required for mitophagy in yeast. We and others recently found that Parkin, an E3 ligase which is commonly mutated in Parkinson's disease, promotes damaged mitochondria ubiquitination and p62 targeting and subsequent mitophagy. Our current research work is to study the molecular signals that could be involved in this process such as redox signaling and mitochondrial fission and fusion machinery. We are also using Parkin knockout mice to investigate the role of Parkin in mitophagy in vivo.
Mitochondria are dynamic organelles and constantly undergo fission and fusion. Fragmented mitochondria may favor autophagic removal due to its small size. We are currently investigating mitochondrial fission and fusion machinery in drug- and alcohol-induced mitophagy and its implication in liver injury.
CCCP induces Parkin-mediated mitophagy. Hela cells were transfected with mCherry parkin and treated with CCCP for 6 hrs.
Ding et al., JBC 2010 Ding et al., JBC 2012; Ding et al Biol Chem. 2012; Williams et al JBC 2015; Williams et al AJP 2015; Ni et al, Redox Biology 2015, Williams et al, Pharm Res 2015, Williams et al, Biol. Chem 2018
3. Targeting autophagy for drug-induced liver injury.
The liver is a vital organ that has a wide range of functions. One of the major functions of the liver is to metabolize and detoxify drugs. Consequently, liver is also often the major target to be damaged by drugs. Drug-induced liver injury is one of the most frequent reasons for the withdrawal of an approved drug from the market, and it accounts for up to 50% of acute liver failure cases. Acetaminophen (APAP) is a safe drug at therapeutic levels, but an overdose can cause severe liver injury in animals and man. We recently demonstrated that pharmacological induction of autophagy significantly inhibits APAP-induced liver injury in mouse by removing APAP-induced damaged mitochondria, a process called mitophagy. Induction of mitophagy can attenuate APAP-induced mitochondrial-mediated oxidative stress. Mechanistically, we demonstrated that acetaminophen administration activates Parkin, an E3 ubiquitin ligase, resulting in Parkin mitochondrial translocation and mitophagy in wild type mice. Intriguingly, we found that Parkin knockout mice are not more susceptible but rather are resistant to acetaminophen-induced liver injury due to compensatory effects. Acute knockdown of Parking using an adenovirus shRNA Parkin can overcome the compensatory effects of chronic genetic loss of Parkin. Our studies also raised concerns on the data interpretation for using genetic knockout mice. We are currently actively in investigating the role of Pink1, an upstream kinase of Parkin, in acetaminophen-induced liver injury. We are also investigating the role of mitochondria dynamics in acetaminophen-induced liver injury. With the rapid progress in the discovery of autophagy inducers rather than rapamycin, targeting autophagy could be a novel avenue for treating the APAP overdose patients.
Ni et al., Hepatology 2012; Ni et al., Autophagy, 2012; Ni et al., Toxi Sciences 2012; Ni et al., Pharm. Res. 2012; Ni et al., Redox Biology 2013, Williams, et al JBC, 2015.
We recently also made another important contribution to demonstrate that autophagy is important to remove acetaminophen protein adducts, in particular mitochondrial protein adducts, which are believed to be the initial trigger to induce mitochondria damage and subsequent necrosis. We also found that p62/SQSTM1, an autophagy receptor protein, is important for selective removal of APAP-adducts by autophagy.
Ni et al., J Hepatology 2016; Chao X et al., Liver International 2018.
4. SQSTM1/p62 mediated-Nrf2 activation promotes liver injury and tumorigenesis in Atg5 liver-specific knockout mice
Autophagy-deficient livers have increased accumulation of p62/SQSTM1, an autophagy substrate and receptor protein. p62 competes with Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) for binding to Keap1 (Kelch-like ECH-associated protein 1) resulting in dissociation of Nrf2 from Keap1 and activation of Nrf2, a transcription factor which regulates expression of cytoprotective genes and hepatic detoxification enzymes. Accumulation of p62 and activation of Nrf2 have been found in human HCCs. Interestingly, we recently demonstrated that p62/SQSTM1-mediated Nrf2 activation is the detrimental factor for the loss of hepatocyte Atg5-induced liver injury, fibrosis and eventual tumorigenesis. Ongoing work is aimed to determine how Nrf2, a traditional thought "good transcriptional factor" for antioxidant genes protecting against oxidative stress, actually cause cell death and tumorigenesis in Atg5-deficient liver. We are currently actively investigating the role of mTOR in Atg5-defiiency-induced liver injury and liver tumorigenesis.
Ni et al., J Hepatology 2014.
Selected Publications (recent 3 years)
Ding, W.X. and Jaeschke, H. (2016) Autophagy in Macrophages Regulates the Inflammasome and Protects Against Liver Injury. J Hepatology. 64(1): 16-8. PMID: 26456339. PMC4888871.
Xiong X, Wang G, Tao R, Wu P, Kono T, Li K, Ding WX, Tong X, Tersey SA, Harris RA, Mirmira RG, Evans-Molina C, Dong XC (2015). Sirtuin 6 regulates glucose-stimulated insulin secretion in mouse pancreatic beta cells. Diabetologia. PMID26471901.
Li, Y and Ding, W.X. (2016) A Gene Transcription Program Decides the Differential Regulation of Autophagy by acute vs Chronic Ethanol? Alcohol Clin Exp Res. 40(1):47-9. PMID: 26727521.
Wang S., Ni, H.M., Dorko, K., Kumer, S.C., Schmitt, T.M., Nawabi, A., Huang H and Ding, W.X. (2016) Increased hepatic expression of receptor interacting protein 3 due to impaired proteasomal functions contributes to Alcohol-induced steatosis and liver injury. Oncotarget 7(14):17681-98. PMID. 26769816. PMCID: PMC4951242.
Qian P, He XC, Paulson A, Li Z, Tao F, Perry JM, Guo F, Zhao M, Zhi L, Venkatraman A, Haug JS, Parmely T, Li H, Dobrowsky RT, Ding WX, Kono T, Ferguson-Smith AC, Li L. (2016) The Dlk1-Gtl2 Locus Preserves LT-HSC Function by Inhibiting the PI3K-mTOR Pathway to Restrict Mitochondrial Metabolism. Cell Stem Cell. 18(2):214-228. PMID: 26627594.
Klionsky, D., …, Ding, W.X., ..et al. (2016) Guidelines for the Use and Interpretation of Assays for Monitoring Autophagy (3rd edition). Autophagy. 12(1):1-222. PMID: 26799652. PMCID: PMC in progress.
Ni, H.M., McGill., M.R, Chao, X., Du, K., Williams, J.A., Xie, Y., Jaeschke, H., and Ding W.X. (2016) Removal of Acetaminophen-Protein Adducts by Autophagy Protects Against Acetaminophen-Induced Liver Injury in Mice. J of Hepatology. 65(2):354-62. PMID: 27151180. PMCID: PMC4955750.
Nagy, L.E., Ding, W.X., Cresci, G., Saikia, P and Shah, V. (2016) Linking pathogenic mechanisms of alcoholic liver disease with clinical phenotypes. Gastroenterology. 150(8):1756-68. PMID: 26919968. PMCID: PMC4887335.
Pan, J.A., Sun, Y., Jaber, N., Dou, Z., Yang, B., Chen, J.S., Catanzaro, J.M., Du, C., Ding, W.X., Moscat, J., Ozato, K., and Zong, W.X. (2016) TRIM21 suppresses protein sequestration and anti-oxidant response by ubiquitylating SQSTM1/p62. Mol Cell. 3;61(5):720-33. PMID: 26942676. PMCID; PMC4779181.
Li Y., McGreal S., Zhao, J., Huang, R., Zhou, Y., Zhong, H., Xia M and Ding, W.X. A cell-based quantitative high-throughput imaging screening identified novel autophagy modulators. (2016) Pharm. Res. 110:35-49. PMID: 27168224. PMCID PMC4995889.
Wang S.G., Pacher, P., De Lisle, R.C., Huang, H., and Ding, W.X. (2016) A mechanistic review of cell death in alcohol-induced liver injury. Alcohol Clin Exp Res. 2016 Apr 30. PMID: 27130888.
Ni, H.M., McGill, M.R, Chao, X., Woolbright, B., Jaeschke, H., and Ding W.X. (2016). Caspase inhibition prevents TNF-α-induced apoptosis and promotes necrotic cell death in mouse hepatocytes in vivo and in vitro. Am J. Pathol. 186(10):2623-36. PMID: 27616656. Selected as AJP Press Release.
Yang, H, Ni, HM, Guo, F, Ding, Y, Shi, YH, Lahiri, P, Fröhlich, LF, Rülicke, T, Smole, C, Schmidt, VC, Zatloukal, K, Cui, Y, Komatsu, M, Fan, J, Ding, WX. (2016) Sequestosome-1/p62 is associated with autophagic removal of excess endoplasmic reticulum in mice. J Biol Chem. 291(36):18663-74. PMID: 27325701. PMCID: PMC5009243.
Zhou, Y., Li, Y., Ni, H.M., Ding, W.X. and Zhong, H. (2016) Nrf2 but not autophagy inhibition is associated with the survival of wild-type epidermal growth factor receptor non-small lung cancer cells. Toxicol Appl Pharmacol. 310:140-149. PMID: 27639429. PMCID:
Wang, S. and Ding, W.X. (2016) A small RNA in neutrophils protects against acute-on-chronic liver injury. Gut 66(4):565-566. PMID: 27802158.
Li, Y. and Ding, W.X. (2017) Does genetic loss of immunoglobulin A have no impact on alcoholic liver disease? Alcohol Clin Exp Res. 41(1):20-22. PMID: 28042659. PMCID: PMC5215837.
Wang, Y., Ding, Y., Li, J., Chavan, H, Matye, D., Ni, H.M., Yoshimori, T., Chiang, Y.L., Krishnamurthy, P., Ding, W.X. and Li, T. (2017) Targeting the enterohepatic bile acid signaling induces hepatic autophagy via a CYP7A1-AKT-mTOR axis in mice. Cellular and Molecular Gastroenterology and Hepatology. 22;3(2):245-260. PMID: 28275691.PMCID:PMC5331786.
Morris, EM., McCoin, C., Allen, J., Gastecki, M., Koch, LG., Britton, SL., Fletcher, JA., Fu, X., , Burgess, SC., Ding, WX., Rector, RS., Thyfault, JP. (2017) Low Aerobic Capacity Increases Susceptibility to High-Fat, High-Cholesterol Diet-Induced Steatohepatitis. J of Physiology. PMID: 28504310.
Williams, J., Zhao, K., Jin, S.K. and Ding, W.X. (2017) New Methods for Monitoring Mitochondrial Biogenesis and Mitophagy in vitro and in vivo. Experimental Biology and Medicine. 242(8):781-787. PMID:28093935. PMCID: PMC5407538.
Yang, X., Wang, H., Ni, H.M., Wang, Z.T., Sesaki, H., Ding, W.X. and Yang, L. (2017) Inhibition of Drp1 protects against senecionine-induced mitochondria-mediated apoptosis in primary hepatocytes and in mice. Redox Biology 2;12:264-273. PMID:28282614. PMCID: PMC5344326.
Woolbright, B., Ding, W.X., and Jaeschke, H. (2017) Caspase inhibitors for the treatment of liver disease: friend or foe? Expert Review for Gastroenterology & Hepatology 4:1-3. PMID:28276808.
Li, Y and Ding, W.X. (2017) Adipose Tissue Autophagy and Homeostasis in Alcohol-Induced Liver Injury. Liver Research 1; 54-62.
Li, Y and Ding, W.X. (2017) Impaired Rab7 and Dynamin2 Block Fat Turnover by Autophagy in Alcoholic Fatty Livers. Hepatology Communications 1(6); 473-475.
New J, Arnold L, Ananth M, Alvi S, Thornton M, Werner L, Tawfik O, Dai H, Shnayder Y, Kakarala K, Tsue TT, Girod D, Ding WX, Anant S, Thomas SM. (2017) Secretory autophagy in cancer-associated fibroblasts promotes head and neck cancer progression and offers a novel therapeutic target. Cancer Research. 1;77(23):6679-6691. PMID:28972076. PMCID: PMC5712244.
Williams, J.A. and Ding, W.X. (2018) Mechanisms, Pathophysiological Roles, and Methods for Analyzing Mitophagy – Recent Insights. Biol Chem. 399(2):147-178. PMID:28976892.
Qian, Q, Zhang, Z, Orwig, A, Chen, S, Ding, WX, Xu, Y, Kunz, RC, Lind, NRL, Stamler, JS, Yang, L. S-nitrosoglutathione Reductase Dysfunction Contributes to Obesity-Associated Hepatic Insulin Resistance via Regulating Autophagy. Diabetes. 2017 Oct 26. PMID: 29074597. PMCID: PMC5959334.
Qiang, H, Chao, X and Ding, W.X. (2018) A PINK1-Mediated Mitophagy Pathway Decides the Fate a Tumor to be Benign or Malignant? Autophagy.9: 1-13. PMID 29313453.PMCID:
Wang, S., Wang, H, and Ding, W.X. (2018) Pyroptosis, a novel target for alcoholic hepatitis? Hepatology. ;67(5):1660-1662. PMID: 29222919. PMCID: PMC5906175.
Lang, A.L., Chen, L., Poff, G.D., Ding, W.X. Barnett, R.A., Arteel, G.E. and Beier, J.I. (2018) Vinyl chloride dysregulates metabolic homeostasis and enhances diet-induced liver injury in mice. Hepatology Communications. 9;2(3):270-284. PMID: 29507902. PMCID: PMC5831023.
Wang, Y., Ding, W.X. and Li, T. (2018) Cholesterol and bile acid-mediated regulation of autophagy in fatty liver diseases and atherosclerosis. Biochim Biophys Acta. 2018 Apr 10. PMID: 29653253.
Chao, X., Jaeschke and Ding, W.X. (2018) Role and mechanisms of autophagy in acetaminophen-induced liver injury. Liver International. PMID: 29682868.
Li, Y., Chao, X., Yang, L., Li, T., Ding, W.X. and Ni, H.M. (2018) Impaired Fasting-induced Adaptive Lipid Droplet Biogenesis in Liver-specific Atg5 Deficient Mouse Liver Is Mediated by Persistent Nrf2 Activation. Am. J. Pathol. PMID: 29823835.
Wang Y, Li J, Matye D, Zhang Y, Dennis K, Ding WX and Li T. (2018) Bile acids regulate cysteine catabolism and glutathione regeneration to modulate hepatic sensitivity to oxidative injury. JCI Insight. 2018 Apr 19;3(8). PMID: 29669937.
Wang Y, Ding WX and Li T. (20108) Cholestrol and bile acid-mediated regulation of autophagy in fatty liver diseases and atherosclerosis. Biochim Biophys Acta. 2018 Apr 10;1863(7):726-733. PMID: 29653253.
Chao X, Wang S, Zhao K, Li Y, Williams JA, Li T, Chavan H, Krishnamurthy P, He XC, Li L, Ballabio A, Ni HM, Ding WX. (2018) Impaired TFEB-mediated lysosomal biogenesis in acute-on-chronic alcohol induced-liver injury in mice. Gastroenterology. PMID: 29782848.
Chao, X., Ni, H.M. and Ding, W.X. (2018) Insufficient Autophagy: A Novel Autophagic Flux Scenario Uncovered by Impaired Liver TFEB-Mediated Lysosomal Biogenesis From Chronic Alcohol-Drinking Mice. Autophagy 2018. PMID: 29969942.
Wen-Xing Ding, Ph.D., FAASLD Professor
Department of Pharmacology, Toxicology and Therapeutics
The University of Kansas Medical Center
3901 Rainbow Blvd.
Kansas City, Kansas 66160
Fax: 913- 588-7501