Margaret A. Shupnik, PhD
Graduate School: University of Wisconsin
Primary Appointment: Professor, Medicine, Endocrinology and Metabolism
Secondary Appointment: Molecular Physiology and Biological Physics
Hypothalmic Peptide and Steroid Regulation of Pituitary Gene Transcription; Estrogen Action in Neuroendocrine and Reproductive Tissues; Estrogen Action in Breast Cancer
Email Address: firstname.lastname@example.org
We have two major research areas: (1) regulation of pituitary hormones by hypothalamic peptides and sex steroids; and (2) steroid action and cross-talk with growth factor signaling in breast and endometrial cancer. Hypothalamic and steroid regulation of pituitary hormones: Pituitary hormones play a critical role in metabolism and reproduction. Our research focuses on how hypothalamic peptides and steroids such as estrogen (E) and testosterone (T) modulate pituitary hormone gene transcription. 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 genes by E and T, and frequency-dependent, subunit-specific modulation of transcription by GnRH. The genes have both common and unique regulatory elements, and are regulated by cooperative interactions between these regions. In defining regulatory protein binding to promoters by chromatin immunoprecipitation (ChIP) assays, we see precise binding patterns to LHb and FSHb genes after GnRH treatment, with intervals corresponding to physiological GnRH pulse frequency. Our hypothesis is that pulsatile GnRH regulation of transcription is regulated by transcription factor synthesis and modification (including ubiquitination), differential activation by signaling pathways, and proteasome activity. We are testing this by RNAseq and ChIPseq analysis, activated signaling molecules and transcription factor modification and degradation in clonal cell lines and pre-natally androgenized mice, as a model of polycystic ovarian disease. These animals have altered LH and T secretion, with dysregulated pituitary gene expression and signaling pathways.
Steroid action in cancer: Estrogen is a critical component in the development of breast and endometrial cancer, and its receptor (ER)is often a target for antiestrogen therapy. We find ER rapidly activates some cytoplasmic enzymes, and are examining interactions between ER and components of growth factor intracellular signaling pathways, including STAT transcription factors. STATS are activated in response to both EGF and estrogen, and may serve as a common pathway to both steroid and growth factor-dependent forms of breast cancer, and in therapeutic resistance. We found ERa is a powerful modulator of STAT activity in cytoplasm and nucleus. We are examining the biochemical and biological interactions of these pathways, the role such interactions may have on breast and endometrial cancer cell proliferation and apoptosis, and the role of specific ER and progesterone receptor isoforms may have in therapeutic response and resistance.
Andrade J, Quinn J, Becker R, Shupnik MA.AMP-Activated Protein Kinase is a Key Intermediary in GnRH-stimulated LHβ Gene Transcription Molecular Endocrinology me.2012-1323; doi:10.1210/me.2012-1323
Fox EM, Andrade J, Shupnik MA. Novel actions of estrogen to promote proliferation: integration of cytoplasmic and nuclear pathways. Steroids. 2009 Jul;74(7):622-7. doi: 10.1016/j.steroids.2008.10.014. Epub 2008 Nov 5. Review. PubMed PMID: 18996136; PubMed Central PMCID: PMC2702758.
Chu Z, Andrade J, Shupnik MA, Moenter SM. Differential regulation of gonadotropin-releasing hormone neuron activity and membrane properties by acutely applied estradiol: dependence on dose and estrogen receptor subtype. J Neurosci. 2009 Apr 29;29(17):5616-27. doi: 10.1523/JNEUROSCI.0352-09.2009. PubMed PMID: 19403828; PubMed Central PMCID: PMC2744362.
Walsh HE, Shupnik MA. Proteasome regulation of dynamic transcription factor occupancy on the GnRH-stimulated luteinizing hormone beta-subunit promoter. Mol Endocrinol. 2009 Feb;23(2):237-50. doi: 10.1210/me.2008-0098. Epub 2008 Dec 18. PubMed PMID: 19095772; PubMed Central PMCID: PMC2646621.
Wen J, Li R, Lu Y, Shupnik MA. Decreased BRCA1 confers tamoxifen resistance in breast cancer cells by altering estrogen receptor-coregulator interactions. Oncogene. 2009 Jan 29;28(4):575-86. doi: 10.1038/onc.2008.405. Epub 2008 Nov 10. PubMed PMID: 18997820; PubMed Central PMCID: PMC2714665.
Fox EM, Davis RJ, Shupnik MA. ERbeta in breast cancer--onlooker, passive player, or active protector? Steroids. 2008 Oct;73(11):1039-51. doi: 10.1016/j.steroids.2008.04.006. Epub 2008 Apr 20. Review. PubMed PMID: 18501937; PubMed Central PMCID: PMC2583259
Ferris HA, Shupnik MA. Mechanisms for pulsatile regulation of the gonadotropin subunit genes by GNRH Biol Reprod 2006; 74:993-998
Fox EM, Bernaciak TM, Wen J, Weaver AM, Shupnik MA, Silva CM. 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. Mol Endocrinol. 2008 Aug;22(8):1781-96. doi: 10.1210/me.2007-0419. Epub 2008 Jun 11. PubMed PMID: 18550772; PubMed Central PMCID: PMC2505329.
Haisenleder DJ, Burger LL, Walsh HE, Stevens J, Aylor KW, Shupnik MA, Marshall JC. 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. 2008 Jan;149(1):139-45. Epub 2007 Oct 11. PubMed PMID: 17932215; PubMed Central PMCID: PMC2194612.
Ferris HA, Walsh HE, Stevens J, Fallest PC, Shupnik MA. Luteinizing hormone beta promoter stimulation by adenylyl cyclase and cooperation with gonadotropin-releasing hormone 1 in transgenic mice and LBetaT2 Cells. Biol Reprod. 2007 Dec;77(6):1073-80. Epub 2007 Aug 15. PubMed PMID: 17699734.