All Publications

  • PPARγ (Peroxisome Proliferator-Activated Receptor γ) Deacetylation Suppresses Aging-Associated Atherosclerosis and Hypercholesterolemia. Arteriosclerosis, thrombosis, and vascular biology Zahr, T., Liu, L., Chan, M., Zhou, Q., Cai, B., He, Y., Aaron, N., Accili, D., Sun, L., Qiang, L. 2022


    Atherosclerosis is a medical urgency manifesting at the onset of hypercholesterolemia and is associated with aging. Activation of PPARγ (peroxisome proliferator-activated receptor γ) counteracts metabolic dysfunction influenced by aging, and its deacetylation displays an atheroprotective property. Despite the marked increase of PPARγ acetylation during aging, it is unknown whether PPARγ acetylation is a pathogenic contributor to aging-associated atherosclerosis.Mice with constitutive deacetylation-mimetic PPARγ mutations on lysine residues K268 and K293 (2KR) in an LDL (low-density lipoprotein)-receptor knockout (Ldlr-/-) background (2KR:Ldlr-/-) were aged for 18 months on a standard laboratory diet to examine the cardiometabolic phenotype, which was confirmed in Western-type diet-fed 2KR:Ldlr+/- mice. Whole-liver RNA-sequencing and in vitro studies in bone marrow-derived macrophages were conducted to decipher the mechanism.In contrast to severe atherosclerosis in WT:Ldlr-/- mice, aged 2KR:Ldlr-/- mice developed little to no plaque, which was underlain by a significantly improved plasma lipid profile, with particular reductions in circulating LDL. The protection from hypercholesterolemia was recapitulated in Western-type diet-fed 2KR:Ldlr+/- mice. Liver RNA-sequencing analysis revealed suppression of liver inflammation rather than changes in cholesterol metabolism. This anti-inflammatory effect of 2KR was attributed to polarized M2 activation of macrophages. Additionally, the upregulation of core circadian component Bmal1, perceived to be involved in anti-inflammatory immunity, was observed in the liver and bone marrow-derived macrophages.PPARγ deacetylation in mice prevents the development of aging-associated atherosclerosis and hypercholesterolemia, in association with the anti-inflammatory phenotype of 2KR macrophages.

    View details for DOI 10.1161/ATVBAHA.122.318061

    View details for PubMedID 36453279

  • Lobar versus sublobar resection in clinical stage IA primary lung cancer with occult N2 disease. European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery Liou, D. Z., Chan, M., Bhandari, P., Lui, N. S., Backhus, L. M., Shrager, J. B., Berry, M. F. 2022


    Sublobar resection is increasingly being utilized for early-stage lung cancers, but optimal management when final pathology shows unsuspected mediastinal nodal disease is unclear. This study tested the hypothesis that lobectomy has improved survival compared to sublobar resection for clinical stage IA tumors with occult N2 disease.The use of sublobar resection and lobectomy for patients in the National Cancer Database who underwent primary surgical resection for clinical stage IA non-small cell lung cancer with pathologic N2 disease between 2010 and 2017 was evaluated using logistic regression. Survival was assessed with Kaplan-Meier analysis, log-rank test, and Cox proportional hazards model.A total of 2,419 patients comprised the study cohort, including 320 sublobar resections (13.2%) and 2,099 lobectomies (86.8%). Older age, female sex, smaller tumour size, and treatment at an academic facility predicted the use of sublobar resection. Patients undergoing lobectomy had larger tumors (2.40 vs 2.05 cm, p < 0.001) and more lymph nodes examined (11 vs 5, p < 0.001). Adjuvant chemotherapy use was similar between the two groups (sublobar 79.4% vs lobectomy 77.4%, p = 0.434). Sublobar resection was not associated with worse survival compared to lobectomy in both univariate (5-year survival 46.6% vs 45.2%, p = 0.319) and multivariable Cox proportional hazards analysis (HR 0.97, p = 0.789).Clinical stage IA non-small cell lung cancer patients with N2 disease on final pathology have similar long-term survival with either sublobar resection or lobectomy. Patients with occult N2 disease after sublobar resection may not require reoperation for completion lobectomy but should instead proceed to adjuvant chemotherapy.

    View details for DOI 10.1093/ejcts/ezac440

    View details for PubMedID 36063054

  • Adipsin deficiency does not impact atherosclerosis development in Ldlr(-/-) mice AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM Liu, L., Chan, M., Yu, L., Wang, W., Qiang, L. 2021; 320 (1): 87-92


    Obesity is a potent risk factor for atherosclerotic morbidity and mortality. Cytokines secreted from adipose tissue, namely, adipokines, have been suggested to be actively involved in atherosclerosis. One of the most abundant adipokines, adipsin, is downregulated in obesity. It catalyzes the rate-limiting step of alternative complement activation, which is one of the three complement pathways potentially involved in inflammation in atherosclerosis. Interestingly, adipsin has been identified as a novel biomarker in human coronary artery disease. However, its role in the development of atherosclerosis remains unexplored. We crossed adipsin-/- mice onto an Ldlr-/- background [double-knockout (DKO) mice] and induced atherogenesis by high-fat and high-cholesterol feeding. Metabolic profiles were systemically characterized, and atherosclerotic plaques were measured at both aortic root and arch regions. Western blotting was conducted to assess adipsin level and complement activity. The DKO mice exhibited similar sizes of atherosclerotic lesions as Ldlr-/- control mice at both the aortic root and arch regions. Accordingly, they displayed comparable metabolic parameters, including body weight, insulin sensitivity, and lipid profiles, along with compensated complement activity. Adipsin deficiency does not impact the development of atherosclerosis in Ldlr-/- mice despite its crucial function in alternative complement activation. Therefore, it is unlikely to play an important role in mediating the risk of atherosclerotic complications in obesity.NEW & NOTEWORTHY Adipsin deficiency does not impact the development of atherosclerosis in Ldlr-/- mice despite its crucial function in alternative complement activation. Therefore, it is unlikely to play an important role in mediating the risk of atherosclerotic complications in obesity.

    View details for DOI 10.1152/ajpendo.00440.2020

    View details for Web of Science ID 000613698700010

    View details for PubMedID 33135458

    View details for PubMedCentralID PMC8194410

  • PPAR gamma Deacetylation Confers the Antiatherogenic Effect and Improves Endothelial Function in Diabetes Treatment DIABETES Liu, L., Fan, L., Chan, M., Kraakman, M. J., Yang, J., Fan, Y., Aaron, N., Wan, Q., Carrillo-Sepulveda, M., Tall, A. R., Tabas, I., Accili, D., Qiang, L. 2020; 69 (8): 1793-1803


    Cardiovascular disease (CVD) is the leading cause of death in patients with diabetes, and tight glycemic control fails to reduce the risk of developing CVD. Thiazolidinediones (TZDs), a class of peroxisome proliferator-activated receptor γ (PPARγ) agonists, are potent insulin sensitizers with antiatherogenic properties, but their clinical use is limited by side effects. PPARγ deacetylation on two lysine residues (K268 and K293) induces brown remodeling of white adipose tissue and uncouples the adverse effects of TZDs from insulin sensitization. Here we show that PPARγ deacetylation confers antiatherogenic properties and retains the insulin-sensitizing effects of TZD while circumventing its detriments. We generated mice homozygous with mice with deacetylation-mimetic PPARγ mutations K268R/K293R (2KR) on an LDL-receptor knockout (Ldlr -/- ) background. 2KR:Ldlr -/- mice showed smaller atherosclerotic lesion areas than Ldlr -/- mice, particularly in aortic arches. With rosiglitazone treatment, 2KR:Ldlr -/- mice demonstrated a residual antiatherogenic response and substantial protection against bone loss and fluid retention. The antiatherosclerotic effect of 2KR was attributed to the protection of endothelium, indicated by improved endothelium-dependent vasorelaxation and repressed expression of proatherogenic factors including inducible nitric oxide synthase, interleukin-6, and NADPH oxidase 2. Therefore, manipulating PPARγ acetylation is a promising therapeutic strategy to control risk of CVD in diabetes treatment.

    View details for DOI 10.2337/db20-0217

    View details for Web of Science ID 000550463400018

    View details for PubMedID 32409492

    View details for PubMedCentralID PMC7372079

  • Identification of a natural beige adipose depot in mice JOURNAL OF BIOLOGICAL CHEMISTRY Chan, M., Lim, Y., Yang, J., Namwanje, M., Liu, L., Qiang, L. 2019; 294 (17): 6751-6761


    Beige fat is a potential therapeutic target for obesity and other metabolic diseases due to its inducible brown fat-like functions. Inguinal white adipose tissue (iWAT) can undergo robust brown remodeling with appropriate stimuli and is therefore widely considered as a representative beige fat depot. However, adipose tissues residing in different anatomic depots exhibit a broad range of plasticity, raising the possibility that better beige fat depots with greater plasticity may exist. Here we identified and characterized a novel, naturally-existing beige fat depot, thigh adipose tissue (tAT). Unlike classic WATs, tAT maintains beige fat morphology at room temperature, whereas high-fat diet (HFD) feeding or aging promotes the development of typical WAT features, namely unilocular adipocytes. The brown adipocyte gene expression in tAT is consistently higher than in iWAT under cold exposure, HFD feeding, and rosiglitazone treatment conditions. Our molecular profiling by RNA-Seq revealed up-regulation of energy expenditure pathways and repressed inflammation in tAT relative to eWAT and iWAT. Furthermore, we demonstrated that the master fatty acid oxidation regulator peroxisome proliferator-activated receptor α is dispensable for maintaining and activating the beige character of tAT. Therefore, we have identified tAT as a natural beige adipose depot in mice with a unique molecular profile that does not require peroxisome proliferator-activated receptor α.

    View details for DOI 10.1074/jbc.RA118.006838

    View details for Web of Science ID 000467394700013

    View details for PubMedID 30824545

    View details for PubMedCentralID PMC6497956

  • The depot-specific and essential roles of CBP/p300 in regulating adipose plasticity JOURNAL OF ENDOCRINOLOGY Namwanje, M., Liu, L., Chan, M., Aaron, N., Kraakman, M. J., Qiang, L. 2019; 240 (2): 257-269


    Fat remodeling has been extensively explored through protein deacetylation, but not yet acetylation, as a viable therapeutic approach in the management of obesity and related metabolic disorders. Here, we investigated the functions of key acetyltransferases CBP/p300 in adipose remodeling and their physiological effects by generating adipose-specific deletion of CBP (Cbp-AKO), p300 (p300-AKO) and double-knockout (Cbp/p300-AKO) models. We demonstrated that Cbp-AKO exhibited marked brown remodeling of inguinal WAT (iWAT) but not epididymal WAT (eWAT) after cold exposure and that this pattern was exaggerated in diet-induced obesity (DIO). Despite this striking browning phenotype, loss of Cbp was insufficient to impact body weight or glucose tolerance. In contrast, ablation of p300 in adipose tissues had minimal effects on fat remodeling and adiposity. Surprisingly, double-knockout mice (Cbp/p300-AKO) developed severe lipodystrophy along with marked hepatic steatosis, hyperglycemia and hyperlipidemia. Furthermore, we demonstrated that pharmacological inhibition of Cbp and p300 activity suppressed adipogenesis. Collectively, these data suggest that (i) CBP, but not p300, has distinct functions in regulating fat remodeling and that this occurs in a depot-selective manner; (ii) brown remodeling occurs independently of the improvements in glucose metabolism and obesity and (iii) the combined roles of CBP and p300 are indispensable for normal adipose development.

    View details for DOI 10.1530/JOE-18-0361

    View details for Web of Science ID 000453043400014

    View details for PubMedID 30530904

    View details for PubMedCentralID PMC6813822

  • PPAR gamma deacetylation dissociates thiazolidinedione's metabolic benefits from its adverse effects JOURNAL OF CLINICAL INVESTIGATION Kraakman, M. J., Liu, Q., Postigo-Fernandez, J., Ji, R., Kon, N., Larre, D., Namwanje, M., Fan, L., Chan, M., Area-Gomez, E., Fu, W., Creusot, R. J., Qiang, L. 2018; 128 (6): 2600-2612


    Thiazolidinediones (TZDs) are PPARγ agonists with potent insulin-sensitizing effects. However, their use has been curtailed by substantial adverse effects on weight, bone, heart, and hemodynamic balance. TZDs induce the deacetylation of PPARγ on K268 and K293 to cause the browning of white adipocytes. Here, we show that targeted PPARγ mutations resulting in constitutive deacetylation (K268R/K293R, 2KR) increased energy expenditure and protected from visceral adiposity and diet-induced obesity by augmenting brown remodeling of white adipose tissues. Strikingly, when 2KR mice were treated with rosiglitazone, they maintained the insulin-sensitizing, glucose-lowering response to TZDs, while displaying little, if any, adverse effects on fat deposition, bone density, fluid retention, and cardiac hypertrophy. Thus, deacetylation appears to fulfill the goal of dissociating the metabolic benefits of PPARγ activation from its adverse effects. Strategies to leverage PPARγ deacetylation may lead to the design of safer, more effective agonists of this nuclear receptor in the treatment of metabolic diseases.

    View details for DOI 10.1172/JCI98709

    View details for Web of Science ID 000433908900037

    View details for PubMedID 29589839

    View details for PubMedCentralID PMC5983311

  • Testing the cancer stem cell hypothesis using the hybrid spheroid assay and Koch's postulates Lange, C. S., Syed, T., Zhang, M., Sabalvaro, C., Lim, H. I., Salame, G., Chilli, B., Llonzo, I., Ansari, A., Chan, M., Li, C., Xu, J., Chen, X. AMER ASSOC CANCER RESEARCH. 2016
  • First visualization of the cancer stem cell niche for solid tumors and the effects of radiation dose on its architecture. Radiation Research 60th Annual Meeting Lange, C., Syed, T., Zhang, M., Sabalvaro, C., Lim, H., Salame, G., Palileo, A., Chan, M., Li, C. 2014