Bio

Bio


Annie Nguyen-Lin is a post-doctoral clinical fellow in Cutaneous Lymphoma. She completed a research fellowship at the National Institutes of Health, then went on to earn her MD from Stanford University School of Medicine. Dr. Nguyen-Lin completed her Internal Medicine Residency at Santa Clara Valley Medical Center, where she was the recipient of the Resident Teaching Award for excellence in medical student education. She is board certified by the American Board of Internal Medicine, and is a member of the American College of Physicians.

Professional Education


  • Post-doctoral Fellowship, Stanford Cutaneous Lymphoma Fellowship (2014)
  • Internal Medicine Residency, Santa Clara Valley Medical Center (2014)
  • Doctor of Medicine, Stanford University School of Medicine (2011)
  • Research Fellowship, The National Institutes of Health (2006)
  • Bachelor of Science, The George Washington University (2004)

Stanford Advisors


  • Youn Kim, Postdoctoral Faculty Sponsor

Publications

Journal Articles


  • G(s)alpha Deficiency in Adipose Tissue Leads to a Lean Phenotype with Divergent Effects on Cold Tolerance and Diet-Induced Thermogenesis CELL METABOLISM Chen, M., Chen, H., Nguyen, A., Gupta, D., Wang, J., Lai, E. W., Pacak, K., Gavrilova, O., Quon, M. J., Weinstein, L. S. 2010; 11 (4): 320-330

    Abstract

    G(s)alpha, the G protein that mediates receptor-stimulated cAMP generation, has been implicated as a regulator of adipogenesis and adipose tissue function. Heterozygous G(s)alpha mutations lead to obesity in Albright hereditary osteodystrophy (AHO) patients and in mice. In this study, we generated mice with adipose-specific G(s)alpha deficiency. Heterozygotes had 50% loss of G(s)alpha expression in adipose tissue and no obvious phenotype, suggesting that adipose-specific G(s)alpha deficiency is not the cause of obesity in AHO. Homozygotes (FGsKO) had severely reduced adipose tissue, indicating that G(s)alpha is required for adipogenesis. Although FGsKO mice had impaired cold tolerance and reduced responsiveness of brown adipose tissue (BAT) to sympathetic signaling, diet-induced thermogenesis and fatty acid oxidation in skeletal muscle were increased. In normal mice, high-fat diet raised sympathetic nerve activity in muscle, but not in BAT. Our results show that cold- and diet-induced thermogenesis may occur in separate tissues, especially when BAT function is impaired.

    View details for DOI 10.1016/j.cmet.2010.02.013

    View details for Web of Science ID 000276546700014

    View details for PubMedID 20374964

  • Alternative Gnas gene products have opposite effects on glucose and lipid metabolism. Proceedings of the National Academy of Sciences of the United States of America Chen, M., Gavrilova, O., Liu, J., Xie, T., Deng, C., Nguyen, A. T., Nackers, L. M., Lorenzo, J., Shen, L., Weinstein, L. S. 2005; 102 (20): 7386-91

    Abstract

    Gnas is an imprinted gene with multiple gene products resulting from alternative splicing of different first exons onto a common exon 2. These products include stimulatory G protein alpha-subunit (G(s)alpha), the G protein required for receptor-stimulated cAMP production; extralarge G(s)alpha (XLalphas), a paternally expressed G(s)alpha isoform; and neuroendocrine-specific protein (NESP55), a maternally expressed chromogranin-like protein. G(s)alpha undergoes tissue-specific imprinting, being expressed primarily from the maternal allele in certain tissues. Heterozygous mutation of exon 2 on the maternal (E2m-/+) or paternal (E2+/p-) allele results in opposite effects on energy metabolism. E2m-/+ mice are obese and hypometabolic, whereas E2+/p- mice are lean and hypermetabolic. We now studied the effects of G(s)alpha deficiency without disrupting other Gnas gene products by deleting G(s)alpha exon 1 (E1). E1+/p- mice lacked the E2+/p- phenotype and developed obesity and insulin resistance. The lean, hypermetabolic, and insulin-sensitive E2+/p- phenotype appears to result from XLalphas deficiency, whereas loss of paternal-specific G(s)alpha expression in E1+/p- mice leads to an opposite metabolic phenotype. Thus, alternative Gnas gene products have opposing effects on glucose and lipid metabolism. Like E2m-/+ mice, E1m-/+ mice had s.c. edema at birth, presumably due to loss of maternal G(s)alpha expression. However, E1m-/+ mice differed from E2m-/+ mice in other respects, raising the possibility for the presence of other maternal-specific gene products. E1m-/+ mice had more severe obesity and insulin resistance and lower metabolic rate relative to E1+/p- mice. Differences between E1m-/+ and E1+/p- mice presumably result from differential effects on G(s)alpha expression in tissues where G(s)alpha is normally imprinted.

    View details for DOI 10.1073/pnas.0408268102

    View details for PubMedID 15883378

  • Increased glucose tolerance and reduced adiposity in the absence of fasting hypoglycemia in mice with liver-specific Gs alpha deficiency. The Journal of clinical investigation Chen, M., Gavrilova, O., Zhao, W. Q., Nguyen, A., Lorenzo, J., Shen, L., Nackers, L., Pack, S., Jou, W., Weinstein, L. S. 2005; 115 (11): 3217-27

    Abstract

    The G protein G(s)alpha is essential for hormone-stimulated cAMP generation and is an important metabolic regulator. We investigated the role of liver G(s)-signaling pathways by developing mice with liver-specific G(s)alpha deficiency (LGsKO mice). LGsKO mice had increased liver weight and glycogen content and reduced adiposity, whereas survival, body weight, food intake, and metabolic rates at ambient temperature were unaffected. LGsKO mice had increased glucose tolerance with both increased glucose-stimulated insulin secretion and increased insulin sensitivity in liver and muscle. Fed LGsKO mice were hypoglycemic and hypoinsulinemic, with low expression of hepatic gluconeogenic enzymes and PPARgamma coactivator-1. However, LGsKO mice maintained normal fasting glucose and insulin levels, probably due to prolonged breakdown of glycogen stores and possibly increased extrahepatic gluconeogenesis. Lipid metabolism was unaffected in fed LGsKO mice, but fasted LGsKO mice had increased lipogenic and reduced lipid oxidation gene expression in liver and increased serum triglyceride and FFA levels. LGsKO mice had very high serum glucagon and glucagon-like peptide-1 levels and pancreatic alpha cell hyperplasia, probably secondary to hepatic glucagon resistance and/or chronic hypoglycemia. Our results define novel roles for hepatic G(s)-signaling pathways in glucose and lipid regulation, which may prove useful in designing new therapeutic targets for diabetes and obesity.

    View details for DOI 10.1172/JCI24196

    View details for PubMedID 16239968

  • Metal-catalyzed oxidation induces carbonylation of peroxisomal proteins and loss of enzymatic activities. Archives of biochemistry and biophysics Nguyen, A. T., Donaldson, R. P. 2005; 439 (1): 25-31

    Abstract

    Peroxisomes are involved in oxidative metabolic reactions and have the capacity to generate large amounts of reactive oxygen species that could damage biomolecules including their own resident proteins. The purpose of this study was to determine whether peroxisomal proteins are susceptible to oxidation and whether oxidative damage affects their enzymatic activity. Peroxisomal proteins were subjected to metal-catalyzed oxidation (MCO) with CuCl(2)/ascorbate and derivatized with 2,4-dinitrophenylhydrazine which allowed for spectrophotometric quantification of carbonylation. Immunochemical detection of carbonylated peroxisomal proteins, resolved by gel electrophoresis and detected with anti-DNP antibodies, revealed five oxidatively modified proteins with the following molecular weights: 80, 66, 62, 55, and 50 kDa. The proteins at 66, 62, and 55 kDa were identified as malate synthase (MS), isocitrate lyase, and catalase (CAT), respectively. MS and CAT were estimated to contain 2-3 mol of carbonyl/mol of protein as a result of MCO. Enzymatic assays revealed varying degrees of activity loss. Isocitrate lyase and malate synthase showed significant loss of activity while catalase and malate dehydrogenase were less inhibited by carbonylation. Our findings show that peroxisomal proteins are vulnerable to MCO damage and thus may also be affected by in vivo exposure to reactive oxygen species.

    View details for DOI 10.1016/j.abb.2005.04.018

    View details for PubMedID 15922287

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