Bio

Clinical Focus


  • Endocrinology
  • Diabetes andMetabolism

Academic Appointments


Honors & Awards


  • Mentored Clinical Scientist Development Award (K08), NIDDK (NIH) (2011-2016)
  • Fellow, Stanford Clinical Investigator Pathway (ABIM Research Pathway) (2005-2011)
  • Roy G. Williams Award for Research in Basic Medical Science, UPenn School of Medicine (2002)

Professional Education


  • Fellowship:Stanford Hospital and Clinics (2011) CA
  • Residency:Stanford Hospital and Clinics (2007) CA
  • Internship:Stanford Hospital and Clinics (2006) CA
  • Board Certification: Endocrinology, Diabetes andMetabolism, American Board of Internal Medicine (2010)
  • Board Certification: Internal Medicine, American Board of Internal Medicine (2008)
  • Medical Education:University of Pennsylvania School of Medicine (2005) PA
  • Ph.D., University of Pennsylvania, Cell and Molecular Biology (2003)

Research & Scholarship

Current Research and Scholarly Interests


hormonal regulation of pancreatic beta cell growth, proliferation and function

Publications

Journal Articles


  • Regulation of fasted blood glucose by resistin SCIENCE Banerjee, R. R., Rangwala, S. M., Shapiro, J. S., Rich, A. S., Rhoades, B., Qi, Y., Wang, J., Rajala, M. W., Pocai, A., Scherer, P. E., Steppan, C. M., Ahima, R. S., Obici, S., Rossetti, L., Lazar, M. A. 2004; 303 (5661): 1195-1198

    Abstract

    The association between obesity and diabetes supports an endocrine role for the adipocyte in maintaining glucose homeostasis. Here we report that mice lacking the adipocyte hormone resistin exhibit low blood glucose levels after fasting, due to reduced hepatic glucose production. This is partly mediated by activation of adenosine monophosphate-activated protein kinase and decreased expression of gluconeogenic enzymes in the liver. The data thus support a physiological function for resistin in the maintenance of blood glucose during fasting. Remarkably, lack of resistin diminishes the increase in post-fast blood glucose normally associated with increased weight, suggesting a role for resistin in mediating hyperglycemia associated with obesity.

    View details for Web of Science ID 000189074700047

    View details for PubMedID 14976316

  • Resistin: molecular history and prognosis JOURNAL OF MOLECULAR MEDICINE-JMM Banerjee, R. R., Lazar, M. A. 2003; 81 (4): 218-226

    Abstract

    Obesity and diabetes have reached epidemic proportions worldwide. The antidiabetic thiazolidinedione (TZD) drugs are insulin-sensitizing agents now widely used in the treatment of type 2 diabetes. TZDs are ligands for the nuclear hormone receptor peroxisome proliferator activated receptor gamma, which is a master regulator of adipogenesis and adipocyte metabolism. The molecular mechanisms by which TZDs improve insulin sensitivity have not been fully identified. Here we consider a novel secreted factor first identified as a TZD-suppressible gene in mouse adipocytes, called resistin, and discuss what is currently known about resistin regulation and function in mouse and human.

    View details for DOI 10.1007/s00109-003-0428-9

    View details for Web of Science ID 000183629500002

    View details for PubMedID 12700889

  • Dimerization of resistin and resistin-like molecules is determined by a single cysteine JOURNAL OF BIOLOGICAL CHEMISTRY Banerjee, R. R., Lazar, M. A. 2001; 276 (28): 25970-25973

    Abstract

    Resistin is a peptide hormone secreted by adipocytes. Cysteine residues comprise 11 of 94 (12%) amino acids in resistin. The arrangement of these cysteines is unique to resistin and its recently discovered family of tissue-specific secreted proteins, which have been independently termed resistin-like molecules (RELMs) and the FIZZ (found in inflammatory zone) family. Here we show that resistin is a disulfide-linked homodimer that can be converted to a monomer by reducing conditions. The intestine-specific RELM beta has similar characteristics. Remarkably, however, the adipose-enriched RELM alpha is a monomer under non-reducing conditions. We note that RELM alpha lacks a cysteine residue, closest to the cleaved N terminus, that is present in resistin and RELM beta in multiple species. Conversion of this cysteine to alanine abolishes dimerization of resistin. Thus, a single disulfide bond is necessary to connect two resistin subunits in a homodimer. The additional 10 cysteines most likely participate in intramolecular disulfide bonds that define the conserved structure of the family members. The monomeric nature of RELM alpha suggests structural and potentially functional divergence between resistin and this close family member.

    View details for Web of Science ID 000169823300045

    View details for PubMedID 11358969

  • The hormone resistin links obesity to diabetes NATURE Steppan, C. M., Bailey, S. T., Bhat, S., Brown, E. J., Banerjee, R. R., Wright, C. M., Patel, H. R., Ahima, R. S., Lazar, M. A. 2001; 409 (6818): 307-312

    Abstract

    Diabetes mellitus is a chronic disease that leads to complications including heart disease, stroke, kidney failure, blindness and nerve damage. Type 2 diabetes, characterized by target-tissue resistance to insulin, is epidemic in industrialized societies and is strongly associated with obesity; however, the mechanism by which increased adiposity causes insulin resistance is unclear. Here we show that adipocytes secrete a unique signalling molecule, which we have named resistin (for resistance to insulin). Circulating resistin levels are decreased by the anti-diabetic drug rosiglitazone, and increased in diet-induced and genetic forms of obesity. Administration of anti-resistin antibody improves blood sugar and insulin action in mice with diet-induced obesity. Moreover, treatment of normal mice with recombinant resistin impairs glucose tolerance and insulin action. Insulin-stimulated glucose uptake by adipocytes is enhanced by neutralization of resistin and is reduced by resistin treatment. Resistin is thus a hormone that potentially links obesity to diabetes.

    View details for Web of Science ID 000166434300037

    View details for PubMedID 11201732

  • Mouse and human resistins impair glucose transport in primary mouse cardiomyocytes, and oligomerization is required for this biological action JOURNAL OF BIOLOGICAL CHEMISTRY Graveleau, C., Zaha, V. G., Mohajer, A., Banerjee, R. R., Dudley-Rucker, N., Steppan, C. M., Rajala, M. W., Scherer, P. E., Ahima, R. S., Lazar, M. A., Abel, E. D. 2005; 280 (36): 31679-31685

    Abstract

    The adipocytokine resistin impairs glucose tolerance and insulin sensitivity in rodents. Here, we examined the effect of resistin on glucose uptake in isolated adult mouse cardiomyocytes. Murine resistin reduced insulin-stimulated glucose uptake, establishing the heart as a resistin target tissue. Notably, human resistin also impaired insulin action in mouse cardiomyocytes, providing the first evidence that human and mouse resistin homologs have similar functions. Resistin is a cysteine-rich molecule that circulates as a multimer of a dimeric form dependent upon a single intermolecular disulfide bond, which, in the mouse, involves Cys26; mutation of this residue to alanine (C26A) produces a monomeric molecule that appears to be bioactive in the liver. Remarkably, unlike native resistin, monomeric C26A resistin had no effect on basal or insulin-stimulated glucose uptake in mouse cardiomyocytes. Resistin impairs glucose uptake in cardiomyocytes by mechanisms that involve altered vesicle trafficking. Thus, in cardiomyocytes, both mouse and human resistins directly impair glucose transport; and in contrast to effects on the liver, these actions of resistin require oligomerization.

    View details for DOI 10.1074/jbc.M504008200

    View details for Web of Science ID 000231665200044

    View details for PubMedID 15983036

  • A family of tissue-specific resistin-like molecules PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Steppan, C. M., Brown, E. J., Wright, C. M., Bhat, S., Banerjee, R. R., Dai, C. Y., Enders, G. H., Silberg, D. G., Wen, X. M., Wu, G. D., Lazar, M. A. 2001; 98 (2): 502-506

    Abstract

    We have identified a family of resistin-like molecules (RELMs) in rodents and humans. Resistin is a hormone produced by fat cells. RELMalpha is a secreted protein that has a restricted tissue distribution with highest levels in adipose tissue. Another family member, RELMbeta, is a secreted protein expressed only in the gastrointestinal tract, particularly the colon, in both mouse and human. RELMbeta gene expression is highest in proliferative epithelial cells and is markedly increased in tumors, suggesting a role in intestinal proliferation. Resistin and the RELMs share a cysteine composition and other signature features. Thus, the RELMs together with resistin comprise a class of tissue-specific signaling molecules.

    View details for Web of Science ID 000166485300028

    View details for PubMedID 11209052

  • Studies of the interaction between Rad52 protein and the yeast single-stranded DNA binding protein RPA MOLECULAR AND CELLULAR BIOLOGY Hays, S. L., Firmenich, A. A., Massey, P., Banerjee, R., Berg, P. 1998; 18 (7): 4400-4406

    Abstract

    The RFA1 gene encodes the large subunit of the yeast trimeric single-stranded DNA binding protein replication protein A (RPA), which is known to play a critical role in DNA replication. A Saccharomyces cerevisiae strain carrying the rfa1-44 allele displays a number of impaired recombination and repair phenotypes, all of which are suppressible by overexpression of RAD52. We demonstrate that a rad52 mutation is epistatic to the rfa1-44 mutation, placing RFA1 and RAD52 in the same genetic pathway. Furthermore, two-hybrid analysis indicates the existence of interactions between Rad52 and all three subunits of RPA. The nature of this Rad52-RPA interaction was further explored by using two different mutant alleles of rad52. Both mutations lie in the amino terminus of Rad52, a region previously defined as being responsible for its DNA binding ability (U. H. Mortenson, C. Beudixen, I. Sunjeuaric, and R. Rothstein, Proc. Natl. Acad. Sci. USA 93:10729-10734, 1996). The yeast two-hybrid system was used to monitor the protein-protein interactions of the mutant Rad52 proteins. Both of the mutant proteins are capable of self-interaction but are unable to interact with Rad51. The mutant proteins also lack the ability to interact with the large subunit of RPA, Rfa1. Interestingly, they retain their ability to interact with the medium-sized subunit, Rfa2. Given the location of the mutations in the DNA binding domain of Rad52, a model incorporating the role of DNA in the protein-protein interactions involved in the repair of DNA double-strand breaks is presented.

    View details for Web of Science ID 000074380100078

    View details for PubMedID 9632824

Stanford Medicine Resources: