Erin Shanle - Academia.edu (original) (raw)

Papers by Erin Shanle

Transgenic Research, 2009

Taxadiene synthase gene from Taxus brevifolia was constitutively expressed in the moss Physcomitr... more Taxadiene synthase gene from Taxus brevifolia was constitutively expressed in the moss Physcomitrella patens using a ubiquitin promoter to produce taxa-4(5),11(12)-diene, the precursor of the anticancer drug paclitaxel. In stable moss transformants, taxa-4(5),11(12)-diene was produced up to 0.05% fresh weight of tissue, without significantly affecting the amounts of the endogenous diterpenoids (ent-kaurene and 16-hydroxykaurane). Unlike higher plants that had been genetically modified to produce taxa-4(5),11(12)-diene, transgenic P. patens did not exhibit growth inhibition due to alteration of diterpenoid metabolic pools. Thus we propose that P. patens is a promising alternative host for the biotechnological production of paclitaxel and its precursors.

Biochemistry and molecular biology education : a bimonthly publication of the International Union of Biochemistry and Molecular Biology, Jan 5, 2015

Course-based undergraduate research experiences (CUREs) provide an opportunity for students to en... more Course-based undergraduate research experiences (CUREs) provide an opportunity for students to engage in experiments with outcomes that are unknown to both the instructor and students. These experiences allow students and instructors to collaboratively bridge the research laboratory and classroom, and provide research experiences for a large number of students relative to traditional individual mentored research. Here, we describe a molecular biology CURE investigating the impact of clinically relevant mutations found in the bromodomain of the p300 transcriptional regulator on acetylated histone interaction. In the CURE, students identified missense mutations in the p300 bromodomain using the Catalogue of Somatic Mutations in Cancer (COSMIC) database and hypothesized the effects of the mutation on the acetyl-binding function of the domain. They cloned and purified the mutated bromodomain and performed peptide pulldown assays to define its potential to bind to acetylated histones. Up...

American journal of translational research, 2015

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype for which there is a ... more Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype for which there is a need to identify new therapeutic targets. Full-length estrogen receptor beta (ERβ1) may be a possible target given its antiproliferative effects on breast cancer cells. The prognostic significance of ERβ in breast cancer subtypes has remained elusive, and disparate results observed across previously published reports might be due to the detection of multiple ERβ isoforms, the lack of specific antibodies and the use of different cutoffs to define ERβpositivity. The objective of this retrospective study was to determine the association between ERβ1 expression and disease-free and overall survival, as well as Ki67 expression, in non-metastatic TNBC. Immunohistochemical protocols were optimized using xenograft tissues obtained from a breast cancer cell line with inducible ERβ1 expression. ERβ1 localization and expression were assessed in two cohorts of TNBC using the VECTRA(TM) platform. The...

PLoS ONE, 2012

Estrogens play essential roles in the progression of mammary and prostatic diseases. The transcri... more Estrogens play essential roles in the progression of mammary and prostatic diseases. The transcriptional effects of estrogens are transduced by two estrogen receptors, ERa and ERb, which elicit opposing roles in regulating proliferation: ERa is proliferative while ERb is anti-proliferative. Exogenous expression of ERb in ERa-positive cancer cell lines inhibits cell proliferation in response to estrogen and reduces xenografted tumor growth in vivo, suggesting that ERb might oppose ERa's proliferative effects via formation of ERa/b heterodimers. Despite biochemical and cellular evidence of ERa/b heterodimer formation in cells co-expressing both receptors, the biological roles of the ERa/b heterodimer remain to be elucidated. Here we report the identification of two phytoestrogens that selectively activate ERa/b heterodimers at specific concentrations using a cell-based, two-step high throughput small molecule screen for ER transcriptional activity and ER dimer selectivity. Using ERa/b heterodimer-selective ligands at defined concentrations, we demonstrate that ERa/b heterodimers are growth inhibitory in breast and prostate cells which co-express the two ER isoforms. Furthermore, using Automated Quantitative Analysis (AQUA) to examine nuclear expression of ERa and ERb in human breast tissue microarrays, we demonstrate that ERa and ERb are co-expressed in the same cells in breast tumors. The co-expression of ERa and ERb in the same cells supports the possibility of ERa/b heterodimer formation at physio-and pathological conditions, further suggesting that targeting ERa/b heterodimers might be a novel therapeutic approach to the treatment of cancers which coexpress ERa and ERb.

Planta, 2009

Gibberellins are ent-kaurene derived phytohormones that are involved in seed germination, stem el... more Gibberellins are ent-kaurene derived phytohormones that are involved in seed germination, stem elongation, and flower induction in seed plants, as well as in antheridia formation and spore germination in ferns. Although ubiquitous in vascular plants, the occurrence and potential function(s) of gibberellins in bryophytes have not yet been resolved. To determine the potential role of gibberellin and/or gibberellin-like compounds in mosses, the effect of AMO-1618 on spores of Physcomitrella patens (Hedw.) B.S.G. was tested. AMO-1618, which inhibited ent-kaurene and gibberellin biosynthesis in angiosperms, also inhibited the bifunctional copalyl diphosphate synthase (E.C. 5.5.1.13)/ent-kaurene synthase (E.C. 4.2.3.19) of P. patens. AMO-1618 also caused a decrease in spore germination rates of P. patens, and this inhibitory effect was less pronounced in the presence of ent-kaurene. These results suggest that ent-kaurene biosynthesis is required by P. patens spores to germinate, implying the presence of gibberellin-like phytohormones in mosses.

Molecular Endocrinology, 2013

Breast cancers that are negative for estrogen receptor ␣ (ER␣), progesterone receptor, and human ... more Breast cancers that are negative for estrogen receptor ␣ (ER␣), progesterone receptor, and human epidermal growth factor receptor 2 are known as triple-negative breast cancers (TNBC). TNBCs are associated with an overall poor prognosis because they lack expression of therapeutic targets like ER␣ and are biologically more aggressive. A second estrogen receptor, ER␤, has been found to be expressed in 50 -90% of ER␣-negative breast cancers, and ER␤ expression in TNBCs has been shown to correlate with improved disease-free survival and good prognosis. To elucidate the role of ER␤ in regulating gene expression and cell proliferation in TNBC cells, the TNBC cell line MDA-MB-468 was engineered with inducible expression of full length ER␤. In culture, ER␤ expression inhibited cell growth by inducing a G1 cell cycle arrest, which was further enhanced by 17␤-estradiol treatment. In xenografts, ER␤ expression also inhibited tumor formation and growth, and 17␤estradiol treatment resulted in rapid tumor regression. Further, genomic RNA sequencing identified both ligand dependent and independent ER␤ target genes, some of which were also regulated by ER␤ in other TNBC cell lines and correlated with ER␤ expression in a cohort of TNBCs from the Cancer Genome Atlas Network. ER␤ target genes were enriched in genes that regulate cell death and survival, cell movement, cell development, and growth and proliferation, as well as genes involved in the Wnt/␤-catenin and the G1/S cell cycle phase checkpoint pathways. In addition to confirming the anti-proliferative effects of ER␤ in TNBC cells, these data provide a comprehensive resource of ER␤ target genes and suggest that ER␤ may be targeted with ligands that can stimulate its growth inhibitory effects.

Journal of Molecular Endocrinology, 2012

Ligand structure can affect the activation of nuclear receptors, such as estrogen receptors (ERs)... more Ligand structure can affect the activation of nuclear receptors, such as estrogen receptors (ERs), and their control of signaling pathways for cellular responses including death and differentiation. We hypothesized that distinct biological functions of similar estradiol (E 2 ) analogs could be identified by integrating gene expression patterns obtained from human tumor cell lines with receptor binding and functional data for the purpose of developing compounds for treatment of a variety of diseases. We compared the estrogen receptor subtype selectivity and impact on signaling pathways for three distinct, but structurally similar, analogs of E 2 . Modifications in the core structure of E 2 led to pronounced changes in subtype selectivity for estrogen receptors, ER-a or ER-b, along with varying degrees of ER dimerization and activation. While all three E 2 analogs are predominantly ER-b agonists, the cell growth inhibitory activity commonly associated with this class of compounds was detected for only two of the analogs and might be explained by a ligand-specific pattern of gene transcription. Microarray studies using three different human tumor cell lines demonstrated that the analogs distinctly affect the transcription of genes in signaling pathways for chromosome replication, cell death, and oligodendrocyte progenitor cell differentiation. That the E 2 analogs could lower tumor cell viability and stimulate neuronal differentiation confirmed that gene expression data could accurately distinguish biological activity of the E 2 analogs. The findings reported here confirm that cellular responses can be regulated by making key structural alterations to the core structure of endogenous ER ligands.

Chemical Research in Toxicology, 2011

Many endocrine disrupting chemicals (EDCs) adversely impact estrogen signaling by interacting wit... more Many endocrine disrupting chemicals (EDCs) adversely impact estrogen signaling by interacting with two estrogen receptors (ERs): ERα and ERβ. Though the receptors have similar ligand binding and DNA binding domains, ERα and ERβ have some unique properties in terms of ligand selectivity and target gene regulation. EDCs that target ER signaling can modify genomic and nongenomic ER activity through direct interactions with ERs, indirectly through transcription factors such as the aryl hydrocarbon receptor (AhR), or through modulation of metabolic enzymes that are critical for normal estrogen synthesis and metabolism. Many EDCs act through multiple mechanisms as exemplified by chemicals that bind both AhR and ER, such as 3-methylcholanthrene. Other EDCs that target ER signaling include phytoestrogens, bisphenolics, and organochlorine pesticides, and many alter normal ER signaling through multiple mechanisms. EDCs can also display tissue-selective ER agonist and antagonist activities similar to selective estrogen receptor modulators (SERMs) designed for pharmaceutical use. Thus, biological effects of EDCs need to be carefully interpreted because EDCs can act through complex tissue-selective modulation of ERs and other signaling pathways in vivo. Current requirements by the U.S. Environmental Protection Agency require some in vitro and cell-based assays to identify EDCs that target ER signaling through direct and metabolic mechanisms. Additional assays may be useful screens for identifying EDCs that act through alternative mechanisms prior to further in vivo study.

Biochemical Pharmacology, 2011

Advanced Drug Delivery Reviews, 2010

Estrogens regulate growth and development through the action of two distinct estrogen receptors (... more Estrogens regulate growth and development through the action of two distinct estrogen receptors (ERs), ERα and ERβ, which mediate proliferation and differentiation of cells. For decades, ERα mediated estrogen signaling has been therapeutically targeted to treat breast cancer, most notably with the selective estrogen receptor modulator (SERM) tamoxifen. Selectively targeting ERs occurs at two levels: tissue selectivity and receptor subtype selectivity. SERMs have been developed with emphasis on tissue selectivity to target ER signaling for breast cancer treatment. Additionally, new approaches to selectively target the action of ERα going beyond ligand-dependent activity are under current investigation. As evidence of the anti-proliferative role of ERβ accumulates, selectively targeting ERβ is an attractive approach for designing new cancer therapies with the emphasis shifted to designing ligands with subtype selectivity. This review will present the mechanistic and structural features of ERs that determine tissue and subtype selectivity with an emphasis on current approaches to selectively target ERα and ERβ for cancer treatment.

The YEATS domain, found in a number of chromatin-associated proteins, has recently been shown to ... more The YEATS domain, found in a number of chromatin-associated proteins, has recently been shown to have the capacity to bind histone lysine acetylation. Here, we show that the YEATS domain of Taf14, a member of key transcrip-tional and chromatin-modifying complexes in yeast, is a selective reader of histone H3 Lys9 acetylation (H3K9ac). Structural analysis reveals that acetylated Lys9 is sandwiched in an aromatic cage formed by F62 and W81. Disruption of this binding in cells impairs gene transcription and the DNA damage response. Our findings establish a highly conserved acetyllysine reader function for the YEATS domain protein family and highlight the significance of this interaction for Taf14.

Cell, Jan 15, 2015

We characterize the Polycomb system that assembles repressive subtelomeric domains of H3K27 methy... more We characterize the Polycomb system that assembles repressive subtelomeric domains of H3K27 methylation (H3K27me) in the yeast Cryptococcus neoformans. Purification of this PRC2-like protein complex reveals orthologs of animal PRC2 components as well as a chromodomain-containing subunit, Ccc1, which recognizes H3K27me. Whereas removal of either the EZH or EED ortholog eliminates H3K27me, disruption of mark recognition by Ccc1 causes H3K27me to redistribute. Strikingly, the resulting pattern of H3K27me coincides with domains of heterochromatin marked by H3K9me. Indeed, additional removal of the C. neoformans H3K9 methyltransferase Clr4 results in loss of both H3K9me and the redistributed H3K27me marks. These findings indicate that the anchoring of a chromatin-modifying complex to its product suppresses its attraction to a different chromatin type, explaining how enzymes that act on histones, which often harbor product recognition modules, may deposit distinct chromatin domains despit...