- Biomedical Sciences Graduate Program | Margaret A. Shupnik

Margaret A. Shupnik

Education

  • BS, Pennsylvania State University, University Park, PA
  • PhD, University of Wisconsin
  • Postdoc, Harvard School of Public Health

Primary Appointment

  • Professor, Medicine- Endocrinology and Metabolism

Contact

Research Interest(s)

Hypothalamic Peptide and Steroid Regulation of Pituitary Gene Transcription; Estrogen Action in Neuroendocrine and Reproductive Tissues; Estrogen Action in Breast Cancer

Research Description

We have two major research interests, including regulation of pituitary hormones by hypothalamic peptides and sex steroids, and estrogen action and cross-talk with intracellular signaling pathways in breast cancer.

Hypothalamic and steroid regulation of pituitary hormones, estrogen action in neuroendocrine tissues:

Pituitary hormones play a critical role in many processes, including growth, metabolism, reproduction and development. Our laboratory is interested in how hypothalamic peptides and steroids such as estrogen (E) and testosterone (T) directly and indirectly modulate pituitary hormone gene transcription. As one model, we study the gonadotropins, LH (luteinizing hormone) and FSH (follicle stimulating hormone), which control gamete development and the production of E and T from the gonads. LH and FSH each consist of a common alpha and specific beta subunit. We showed subunit-specific regulation of each gene by E and T, and frequency-dependent, subunit-specific modulation of transcription by hypothalamic GnRH. We have found that the genes have both common and unique regulatory elements, and are regulated by cooperative interactions between these regions. We are continuing to define the transcription factors binding to these regions and the coactivator proteins that modulate their activity. By performing chromatin immunoprecipitation (ChIP) assays, we find that there are defined patterns of transcription factor occupancy of the LHbeta gene after GnRH treatment, with intervals corresponding to the physiological GnRH pulse frequency. Our working hypothesis is that pulsatile regulation of gonadotropin gene transcription by GnRH is regulated by transcription factor synthesis and modification, differential activation by intracellular signaling pathways, and proteasome activity. We are testing this by mRNA and protein microarray analysis of transcription factor and signaling genes, measurement of activated signaling molecules, examination of transcription factor modification, and protein degradation studies. Comparison of the subunit genes for GnRH and steroid modulation by transfection, transcription and ChIP analysis will allow us to determine common and distinct regulatory mechanisms. We have also identified and cloned a unique truncated form of the estrogen receptor (ER)-alpha in female rat pituitaries. This receptor, TERP, is transcribed from its own intronic promoter and its expression is regulated by E and physiological state. TERP can modulate ER activity on model promoters positively by titrating repressor proteins, and negatively by forming heterodimers that cannot bind DNA. To understand the physiological role of this receptor, we are examining the interaction of the ER and TERP with regulatory proteins that may modify their activity, regulation of endogenous genes and physiological promoters by TERP, and the physiological consequences of a TERP promoter knock-out in mice. Estrogen action in breast cancer: Estrogen is a critical component in the development of breast cancer, and its nuclear receptor is often a target for antiestrogen therapy. We have found that estrogen, acting through its receptor, can rapidly activate some cytoplasmic enzymes, and we are examining interactions between the estrogen receptor and components of growth factor intracellular signaling pathways, including the STAT transcription factors. The STATS are activated in response to both EGF receptor activation and estrogen, and we propose that they may serve as a common pathway to both steroid and growth factor-dependent forms of breast cancer. We have found that estrogen receptor alpha (ERa) is a powerful modulator of STAT activity, and we have some evidence that this can occur in both the cytoplasm and nucleus. We are examining the biochemical and biological interactions of these pathways, and the role such interactions may have on breast cancer cell proliferation and apoptosis.

Selected Publications

  • Bagchi D, Andrade J, Shupnik M. A new role for wilms tumor protein 1: differential activities of + KTS and -KTS variants to regulate LHβ transcription. PloS one. 2015;10(1): e0116825. PMID: 25617744 | PMCID: PMC4305298
  • Modesitt S, Hallowell P, Slack-Davis J, Michalek R, Atkins K, Kelley S, Arapovic S, Shupnik M, Hoehn K. Women at extreme risk for obesity-related carcinogenesis: Baseline endometrial pathology and impact of bariatric surgery on weight, metabolic profiles and quality of life. Gynecologic oncology. 2015. PMID: 26013696
  • Young N, Wu L, Burd C, Friedman A, Kaffenberger B, Rajaram M, Schlesinger L, James H, Shupnik M, Jarjour W. Estrogen modulation of endosome-associated toll-like receptor 8: an IFNα-independent mechanism of sex-bias in systemic lupus erythematosus. Clinical immunology (Orlando, Fla.). 2014;151(1): 66-77. PMID: 24525049 | PMCID: PMC4066385
  • Andrade J, Quinn J, Becker R, Shupnik M. AMP-activated protein kinase is a key intermediary in GnRH-stimulated LHβ gene transcription. Molecular endocrinology (Baltimore, Md.). 2013;27(5): 828-39. PMID: 23518923 | PMCID: PMC3634116
  • Introduction to the year in basic science series...2009. Molecular endocrinology (Baltimore, Md.). 2009;24(1): 250-1. PMID: 20019125
  • Chu Z, Andrade J, Shupnik M, Moenter S. Differential regulation of gonadotropin-releasing hormone neuron activity and membrane properties by acutely applied estradiol: dependence on dose and estrogen receptor subtype. The Journal of neuroscience : the official journal of the Society for Neuroscience. 2009;29(17): 5616-27. PMID: 19403828 | PMCID: PMC2744362
  • Introduction to The Year in Basic Science series. Molecular endocrinology (Baltimore, Md.). 2008;22(12): 2741-2. PMID: 18845669
  • Fox E, Andrade J, Shupnik M. Novel actions of estrogen to promote proliferation: integration of cytoplasmic and nuclear pathways. Steroids. 2008;74(7): 622-7. PMID: 18996136 | PMCID: PMC2702758
  • Fox E, Bernaciak T, Wen J, Weaver A, Shupnik M, Silva C. Signal transducer and activator of transcription 5b, c-Src, and epidermal growth factor receptor signaling play integral roles in estrogen-stimulated proliferation of estrogen receptor-positive breast cancer cells. Molecular endocrinology (Baltimore, Md.). 2008;22(8): 1781-96. PMID: 18550772 | PMCID: PMC2505329
  • Fox E, Davis R, Shupnik M. ERbeta in breast cancer--onlooker, passive player, or active protector? Steroids. 2008;73(11): 1039-51. PMID: 18501937 | PMCID: PMC2583259
  • Walsh H, Shupnik M. Proteasome regulation of dynamic transcription factor occupancy on the GnRH-stimulated luteinizing hormone beta-subunit promoter. Molecular endocrinology (Baltimore, Md.). 2008;23(2): 237-50. PMID: 19095772 | PMCID: PMC2646621
  • Wen J, Li R, Lu Y, Shupnik M. Decreased BRCA1 confers tamoxifen resistance in breast cancer cells by altering estrogen receptor-coregulator interactions. Oncogene. 2008;28(4): 575-86. PMID: 18997820 | PMCID: PMC2714665
  • Ferris H, Walsh H, Stevens J, Fallest P, Shupnik M. Luteinizing hormone beta promoter stimulation by adenylyl cyclase and cooperation with gonadotropin-releasing hormone 1 in transgenic mice and LBetaT2 Cells. Biology of reproduction. 2007;77(6): 1073-80. PMID: 17699734
  • Haisenleder D, Burger L, Walsh H, Stevens J, Aylor K, Shupnik M, Marshall J. Pulsatile gonadotropin-releasing hormone stimulation of gonadotropin subunit transcription in rat pituitaries: evidence for the involvement of Jun N-terminal kinase but not p38. Endocrinology. 2007;149(1): 139-45. PMID: 17932215 | PMCID: PMC2194612
  • Kowase T, Walsh H, Darling D, Shupnik M. Estrogen enhances gonadotropin-releasing hormone-stimulated transcription of the luteinizing hormone subunit promoters via altered expression of stimulatory and suppressive transcription factors. Endocrinology. 2007;148(12): 6083-91. PMID: 17823254
  • Silva C, Shupnik M. Integration of steroid and growth factor pathways in breast cancer: focus on signal transducers and activators of transcription and their potential role in resistance. Molecular endocrinology (Baltimore, Md.). 2007;21(7): 1499-512. PMID: 17456797