John M. Stafford, Ph.D., M.D.Associate Professor
Nashville, TN 37232-6303
Overview of research topic: Death and disease from obesity are largely due to the development of insulin resistance. Insulin resistance leads to diabetes and a dyslipidemia characterized by high triglycerides and low HDL. Our lab aims to understand how obesity alters control points in lipid metabolism. We focus on the mechanisms by which metabolism of glucose and triglyceride are coordinated -the body's two main energy sources. The corollary is that relatively subtle failure this coordinate regulation could lead to abnormalities in both glucose and lipid metabolism -such as seen with obesity. We also study sex-difference in cardiovascular risk, which may related to the ability of estrogen to coordinate glucose and triglyceride metabolism.
For humans, elevated serum triglycerides lead to elevated triglycerides in other lipoproteins. Triglyceride-enrichment of HDL promotes more rapid HDL clearance, and may impair HDL's protective cardiovascular effects. Rodents do not mimic this biology well. Thus, one research focus is to develop rodent models that are more similar to humans with regard to lipid metabolism. Mice transgenic for cholesteryl ester transfer protein (CETP) have increased transfer of triglyceride into HDL. We have found that cholesteryl ester transfer protein expressing mice model certain HDL changes with obesity. Rodent models with biology more similar to humans may serve as a bridge between basic research and human disease, and help define how obesity and diabetes impact cardiovascular risk
In addition to our experimental goals, a main focus is to train the next generation of scientist. We will create a research environment that is conductive to learning and testing new skills, as well as scientific ideas.
Research and Projects:
Innovative Techniques: The liver coordinates metabolism of the glucose and TG through the convergence of multiple metabolic signals, including hormonal signals such as insulin and glucagon, and substrate concentrations of glucose and fatty acids. The corollary is that relatively subtle failure this convergent signaling could lead to abnormalities in both glucose and lipid metabolism -such as seen in obesity and diabetes. Traditional methods to study liver metabolism in vivo are confounded by counter-regulatory changes in glucose and insulin action. In our lab, our approach has been to use chronically-catheterized mice and rats. We then incorporate metabolic clamp techniques to control serum insulin, glucose, and glucagon levels, and thus avoid compensatory metabolic changes. This approach is the gold standard to define insulin sensitivity in vivo, but has not been widely applied to studying TG metabolism in rodents. On top of physiologic definition of insulin sensitivity and TG production, we use metabolic tracers to define the metabolic fate glucose and synthesis of TG. We overlay cutting-edge proteomics, metabolomics and transcriptomics techniques to relate lipid metabolism to insulin sensitivity.
Specific research projects include:
1) Sex-Differences in Cardiovascular risk: Compared to men, women have a delay in the onset of cardiovascular disease. In some studies, this is as much as 10 to 20 years. Some of this protection may be due to protection from the metabolic complications of obesity, including diabetes and a dyslipidemia characterized by increased VLDL, and low HDL. Our lab is interested in defining the molecular pathways that contribute to sex-differences in cardiovascular risk. We use genetic models with tissue-specific knock-out of estrogen receptor alpha. Our lab has identified important roles of ovarian hormones in protecting from abnormalities in liver metabolism with obesity. We have found that ovarian hormones have a protective role against HDL changes associated with high-fat feeding.
2) HDL composition and function: High density lipoprotein (HDL) protects from coronary heart disease (CHD). HDL prevents inflammation, and accepts cholesterol from tissues by reverse cholesterol transport (RCT). In obesity, HDL may lose its ability to limit inflammation and participate in RCT. In humans, impaired HDL function correlated with the development of obesity, insulin resistance, and fatty liver. Our lab studies how changes in glucose and triglyceride metabolism with obesity contribute to alterations in HDL composition and function. We use both targeted and shotgun proteomics to define HDL composition changes in our obesity models, and relate this to HDL function assays.
Mueller PA, Zhu L, Tavori H, Huynh K, Giunzioni I, Stafford JM, Linton MF, Fazio S. Deletion of Macrophage Low-Density Lipoprotein Receptor-Related Protein 1 (LRP1) Accelerates Atherosclerosis Regression and Increases C-C Chemokine Receptor Type 7 (CCR7) Expression in Plaque Macrophages. Circulation. 2018 Oct 10/23/2018; 138(17): 1850-63. PMID: 29794082, PMCID: PMC6343494, PII: CIRCULATIONAHA.117.031702, DOI: 10.1161/CIRCULATIONAHA.117.031702, ISSN: 1524-4539.
Palmisano BT, Zhu L, Eckel RH, Stafford JM. Sex differences in lipid and lipoprotein metabolism. Mol Metab [print-electronic]. 2018 Sep; 15: 45-55. PMID: 29858147, PMCID: PMC6066747, PII: S2212-8778(18)30315-6, DOI: 10.1016/j.molmet.2018.05.008, ISSN: 2212-8778.
Zhu L, Shi J, Luu TN, Neuman JC, Trefts E, Yu S, Palmisano BT, Wasserman DH, Linton MF, Stafford JM. Hepatocyte estrogen receptor alpha mediates estrogen action to promote reverse cholesterol transport during Western-type diet feeding. Mol Metab [print-electronic]. 2018 Feb; 8: 106-16. PMID: 29331506, PMCID: PMC5985047, PII: S2212-8778(17)30683-X, DOI: 10.1016/j.molmet.2017.12.012, ISSN: 2212-8778.
Palmisano BT, Stafford JM, Pendergast JS. High-Fat Feeding Does Not Disrupt Daily Rhythms in Female Mice because of Protection by Ovarian Hormones. Front Endocrinol (Lausanne). 2017; 8: 44. PMID: 28352249, PMCID: PMC5348546, DOI: 10.3389/fendo.2017.00044, ISSN: 1664-2392.
Palmisano BT, Zhu L, Stafford JM. Role of Estrogens in the Regulation of Liver Lipid Metabolism. Adv. Exp. Med. Biol. 2017; 1043: 227-56. PMID: 29224098, PMCID: PMC5763482, DOI: 10.1007/978-3-319-70178-3_12, ISSN: 0065-2598.
Zhu L, Giunzioni I, Tavori H, Covarrubias R, Ding L, Zhang Y, Ormseth M, Major AS, Stafford JM, Linton MF, Fazio S. Loss of Macrophage Low-Density Lipoprotein Receptor-Related Protein 1 Confers Resistance to the Antiatherogenic Effects of Tumor Necrosis Factor-a Inhibition. Arterioscler. Thromb. Vasc. Biol [print-electronic]. 2016 Aug; 36(8): 1483-95. PMID: 27365402, PMCID: PMC5346022, PII: ATVBAHA.116.307736, DOI: 10.1161/ATVBAHA.116.307736, ISSN: 1524-4636.
Palmisano BT, Le TD, Zhu L, Lee YK, Stafford JM. Cholesteryl ester transfer protein alters liver and plasma triglyceride metabolism through two liver networks in female mice. J. Lipid Res [print-electronic]. 2016 Aug; 57(8): 1541-51. PMID: 27354419, PMCID: PMC4959869, PII: jlr.M069013, DOI: 10.1194/jlr.M069013, ISSN: 1539-7262.
Cholesteryl Ester Transfer Protein Alters Liver and Plasma Triglyceride Metabolism Through Two Liver Networks in Female Mice. JLR. 2016 Jun 6/27/2016.
Loss of Macrophage LDL Receptor Related Protein 1 (LRP1) Confers Resistance to the Anti-atherogenic Effects of TNFa Inhibition. ATVB. 2016 Jun 6/20/2016.
Dai C, Kayton NS, Shostak A, Poffenberger G, Cyphert HA, Aramandla R, Thompson C, Papagiannis IG, Emfinger C, Shiota M, Stafford JM, Greiner DL, Herrera PL, Shultz LD, Stein R, Powers AC. Stress-impaired transcription factor expression and insulin secretion in transplanted human islets. J. Clin. Invest [print-electronic]. 2016 Apr 4/11/2016; PMID: 27064285, PII: 83657, DOI: 10.1172/JCI83657, ISSN: 1558-8238.
Cappel DA, Lantier L, Palmisano BT, Wasserman DH, Stafford JM. CETP Expression Protects Female Mice from Obesity-Induced Decline in Exercise Capacity. PLoS ONE. 2015; 10(8): e0136915. PMID: 26313355, PMCID: PMC4551677, PII: PONE-D-15-17738, DOI: 10.1371/journal.pone.0136915, ISSN: 1932-6203.
Otero YF, Stafford JM, McGuinness OP. Pathway-selective insulin resistance and metabolic disease: the importance of nutrient flux. J. Biol. Chem. 2014 Jul 7/25/2014; 289(30): 20462-9. PMID: 24907277, PMCID: PMC4110258, PII: R114.576355, DOI: 10.1074/jbc.R114.576355, ISSN: 1083-351X.
Zhu L, Martinez MN, Emfinger CH, Palmisano BT, Stafford JM. Estrogen signaling prevents diet-induced hepatic insulin resistance in male mice with obesity. Am. J. Physiol. Endocrinol. Metab [print-electronic]. 2014 May 5/15/2014; 306(10): E1188-97. PMID: 24691030, PMCID: PMC4116406, PII: ajpendo.00579.2013, DOI: 10.1152/ajpendo.00579.2013, ISSN: 1522-1555.
Luo P, Dematteo A, Wang Z, Zhu L, Wang A, Kim HS, Pozzi A, Stafford JM, Luther JM. Aldosterone deficiency prevents high-fat-feeding-induced hyperglycaemia and adipocyte dysfunction in mice. Diabetologia [print-electronic]. 2013 Apr; 56(4): 901-10. PMID: 23314847, PMCID: PMC3593801, DOI: 10.1007/s00125-012-2814-8, ISSN: 1432-0428.
Zhu L, Brown WC, Cai Q, Krust A, Chambon P, McGuinness OP, Stafford JM. Estrogen treatment after ovariectomy protects against fatty liver and may improve pathway-selective insulin resistance. Diabetes [print-electronic]. 2013 Feb; 62(2): 424-34. PMID: 22966069, PMCID: PMC3554377, PII: db11-1718, DOI: 10.2337/db11-1718, ISSN: 1939-327X.
Cappel DA, Palmisano BT, Emfinger CH, Martinez MN, McGuinness OP, Stafford JM. Cholesteryl ester transfer protein protects against insulin resistance in obese female mice. Mol Metab. 2013; 2(4): 457-67. PMID: 24327961, PMCID: PMC3854988, PII: S2212-8778(13)00091-4, DOI: 10.1016/j.molmet.2013.08.007, ISSN: 2212-8778.
Rojas JM, Stafford JM, Saadat S, Printz RL, Beck-Sickinger AG, Niswender KD. Central nervous system neuropeptide Y signaling via the Y1 receptor partially dissociates feeding behavior from lipoprotein metabolism in lean rats. Am. J. Physiol. Endocrinol. Metab [print-electronic]. 2012 Dec 12/15/2012; 303(12): E1479-88. PMID: 23074243, PMCID: PMC3532466, PII: ajpendo.00351.2012, DOI: 10.1152/ajpendo.00351.2012, ISSN: 1522-1555.
Martinez MN, Emfinger CH, Overton M, Hill S, Ramaswamy TS, Cappel DA, Wu K, Fazio S, McDonald WH, Hachey DL, Tabb DL, Stafford JM. Obesity and altered glucose metabolism impact HDL composition in CETP transgenic mice: a role for ovarian hormones. J. Lipid Res [print-electronic]. 2012 Mar; 53(3): 379-89. PMID: 22215797, PMCID: PMC3276461, PII: jlr.M019752, DOI: 10.1194/jlr.M019752, ISSN: 0022-2275.
Wu, K., D. Cappel, M. Martinez, and J.M. Stafford. Impaired-inactivation of FoxO1 contributes to glucose-mediated increases in serum VLDL. Endocrinology. 2010; 151((8)): 3566-76.
Stafford JM, Yu F, Printz R, Hasty AH, Swift LL, Niswender KD. Central nervous system neuropeptide Y signaling modulates VLDL triglyceride secretion. Diabetes [print-electronic]. 2008 Jun; 57(6): 1482-90. PMID: 18332095, PMCID: PMC3968924, PII: db07-1702, DOI: 10.2337/db07-1702, ISSN: 1939-327X.
Stafford JM, Elasy T. Treatment update: thiazolidinediones in combination with metformin for the treatment of type 2 diabetes. Vasc Health Risk Manag. 2007; 3(4): 503-10. PMID: 17969380, PMCID: PMC2291335, ISSN: 1176-6344.
Stafford JM, Wilkinson JC, Beechem JM, Granner DK. Accessory factors facilitate the binding of glucocorticoid receptor to the phosphoenolpyruvate carboxykinase gene promoter. J. Biol. Chem [print-electronic]. 2001 Oct 10/26/2001; 276(43): 39885-91. PMID: 11518712, PII: M105370200, DOI: 10.1074/jbc.M105370200, ISSN: 0021-9258.
Yoon JC, Puigserver P, Chen G, Donovan J, Wu Z, Rhee J, Adelmant G, Stafford J, Kahn CR, Granner DK, Newgard CB, Spiegelman BM. Control of hepatic gluconeogenesis through the transcriptional coactivator PGC-1. Nature. 2001 Sep 9/13/2001; 413(6852): 131-8. PMID: 11557972, PII: 35093050, DOI: 10.1038/35093050, ISSN: 0028-0836.
Stafford JM, Waltner-Law M, Granner DK. Role of accessory factors and steroid receptor coactivator 1 in the regulation of phosphoenolpyruvate carboxykinase gene transcription by glucocorticoids. J. Biol. Chem [print-electronic]. 2001 Feb 2/9/2001; 276(6): 3811-9. PMID: 11069927, PII: M009389200, DOI: 10.1074/jbc.M009389200, ISSN: 0021-9258.
Wang JC, Stafford JM, Scott DK, Sutherland C, Granner DK. The molecular physiology of hepatic nuclear factor 3 in the regulation of gluconeogenesis. J. Biol. Chem. 2000 May 5/12/2000; 275(19): 14717-21. PMID: 10799560, PII: 275/19/14717, ISSN: 0021-9258.
Pierreux CE, Stafford J, Demonte D, Scott DK, Vandenhaute J, O'Brien RM, Granner DK, Rousseau GG, Lemaigre FP. Antiglucocorticoid activity of hepatocyte nuclear factor-6. Proc. Natl. Acad. Sci. U.S.A. 1999 Aug 8/3/1999; 96(16): 8961-6. PMID: 10430878, PMCID: PMC17715, ISSN: 0027-8424.
Wang JC, Stafford JM, Granner DK. SRC-1 and GRIP1 coactivate transcription with hepatocyte nuclear factor 4. J. Biol. Chem. 1998 Nov 11/20/1998; 273(47): 30847-50. PMID: 9812974, PMCID: PMC3968904, ISSN: 0021-9258.
Scott DK, O'Doherty RM, Stafford JM, Newgard CB, Granner DK. The repression of hormone-activated PEPCK gene expression by glucose is insulin-independent but requires glucose metabolism. J. Biol. Chem. 1998 Sep 9/11/1998; 273(37): 24145-51. PMID: 9727036, ISSN: 0021-9258.
We are interested in recruiting an experienced animal physiologist and molecular biologists as a postdoctoral fellow.
The goal of our research program is to define and target pathways to reduce cardiovascular disease associated with obesity and diabetes. Most of our projects center around sex differences in lipoprotein metabolism and risk of atherosclerosis with obesity and diabetes. Our studies involve exposure to techniques ranging from molecular biology to animal physiology. We use in vivo metabolism and tracers to understand how hepatic pathways controlling lipoprotein metabolism are altered with obesity and sex hormones.
Experience with animal surgical techniques is not required but preferred. A research background in diabetes or lipid biology is required. Molecular biology experience is required, though training will be provided for specific techniques. Common techniques include: hyperinsulinemic-euglycemic clamps, atherosclerosis studies, HDL function studies, lipoprotein chromatography and lipid assays, western blots for protein, RT-PCR, cell culture, adenovirus purification.
Ideal applicants will be: bright, enthusiastic, focused on work activities during working-hours, meticulous to detail and record keeping. A high level of independence, autonomy and intellectual collaboration is encouraged.
Applicants must be NIH training grant eligible (US citizen or US permanent resident).
For more information, please contact:
John M. Stafford MD, PhD