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Jason S Carroll

Publications and source records attributed to Jason S Carroll.

17 recordsLinked to original sources
PubMed2026

The transcription factor BACH1 couples chromatin priming and repression to enable macrophage plasticity and adaptation.

Macrophage activation and tissue adaptation involve precise transcriptional control by lineage-determining transcription factors (LDTFs) and stimulus-dependent TFs. The heme-regulated transcriptional repressor BACH1 clusters with myeloid LDTFs in unstimulated macrophages, suggesting a role in shaping macrophage identity and function. We found that BACH1 bound to both inactive and active regulatory regions, including latent enhancers. BACH1 recruited the NuRD complex and had dual functions, establishing early chromatin accessibility while actively repressing transcription. Upon inflammatory stimulation, BACH1 rapidly redistributed in cis to nearby promoters, reshaping chromatin occupancy, motif specificity, and enhancer-promoter interactions. BACH1 constrained 3D chromatin architecture, limiting enhancer mobility and TF complex dynamics. In vivo, Bach1 deletion impaired macrophage polarization and tissue adaptation and limited resilience during systemic and regenerative inflammation. Thus, BACH1 acts as an early chromatin accessibility-priming factor while actively repressing transcription-a regulatory activity that can be defined as pioneer repression-thereby shaping the macrophage epigenome in response to inflammatory and tissue contexts.

Basic-Leucine Zipper Transcription Factors↗
PubMed2025

Why do we continue to have an incomplete understanding of estrogen receptor(s) actions in cancer systems?

The topic proposed asks why we have an incomplete understanding of estrogen receptor (ER) action in cancer. We agree that the role of ER in some cancers is poorly understood, but the role of ER in luminal breast cancer (which represents the biggest subtype of the most common cancer in women) is very well characterised. Although technologies evolve and allow us to learn more about the intricacies of the genome and the multitude of ways breast cancer can adapt to bypass treatments, our understanding of how ER regulates gene expression is extraordinary. We would posit that the key events in ER-mediated cell cycle progression are already known and although new information adds granular information to our paradigms of ER action, we need to better characterise what has been discovered already.

Humans↗
PubMed2006

Genome-wide analysis of estrogen receptor binding sites.

The estrogen receptor is the master transcriptional regulator of breast cancer phenotype and the archetype of a molecular therapeutic target. We mapped all estrogen receptor and RNA polymerase II binding sites on a genome-wide scale, identifying the authentic cis binding sites and target genes, in breast cancer cells. Combining this unique resource with gene expression data demonstrates distinct temporal mechanisms of estrogen-mediated gene regulation, particularly in the case of estrogen-suppressed genes. Furthermore, this resource has allowed the identification of cis-regulatory sites in previously unexplored regions of the genome and the cooperating transcription factors underlying estrogen signaling in breast cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2006

A cell-type-specific transcriptional network required for estrogen regulation of cyclin D1 and cell cycle progression in breast cancer.

Estrogen stimulates the proliferation of the most common type of human breast cancer that expresses estrogen receptor alpha (ERalpha) through the activation of the cyclin D1 (CCND1) oncogene. However, our knowledge of ERalpha transcriptional mechanisms remains limited. Hence, it is still elusive why ERalpha ectopically expressed in ER-negative breast cancer cells (BCC) is functional on ectopic reporter constructs but lacks activity on many endogenous target genes, including CCND1. Here, we show that estradiol (E2) stimulation of CCND1 expression in BCC depends on a novel cell-type-specific enhancer downstream from the CCND1 coding region, which is the primary ERalpha recruitment site in estrogen-responsive cells. The pioneer factor FoxA1 is specifically required for the active chromatin state of this enhancer and as such is crucial for both CCND1 expression and subsequent cell cycle progression. Interestingly, even in BCC, CCND1 levels and proliferation are tightly controlled by E2 through the establishment of a negative feedforward loop involving the induction of NFIC, a putative tumor suppressor capable of directly repressing CCND1 transcription. Taken together, our results reveal an estrogen-regulated combinatorial network including cell-specific cis- and trans-regulators of CCND1 expression where ERalpha collaborates with other transcription factors associated with the ER-positive breast cancer phenotype, including FoxA1 and NFIC.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Model-based analysis of tiling-arrays for ChIP-chip.

We propose a fast and powerful analysis algorithm, titled Model-based Analysis of Tiling-arrays (MAT), to reliably detect regions enriched by transcription factor chromatin immunoprecipitation (ChIP) on Affymetrix tiling arrays (ChIP-chip). MAT models the baseline probe behavior by considering probe sequence and copy number on each array. It standardizes the probe value through the probe model, eliminating the need for sample normalization. MAT uses an innovative function to score regions for ChIP enrichment, which allows robust P value and false discovery rate calculations. MAT can detect ChIP regions from a single ChIP sample, multiple ChIP samples, or multiple ChIP samples with controls with increasing accuracy. The single-array ChIP region detection feature minimizes the time and monetary costs for laboratories newly adopting ChIP-chip to test their protocols and antibodies and allows established ChIP-chip laboratories to identify samples with questionable quality that might contaminate their data. MAT is developed in open-source Python and is available at http://chip.dfci.harvard.edu/ approximately wli/MAT. The general framework presented here can be extended to other oligonucleotide microarrays and tiling array platforms.

Algorithms↗
PubMed2006

p63 regulates an adhesion programme and cell survival in epithelial cells.

p63 is critical for epithelial development yet little is known about the transcriptional programmes it regulates. By characterising transcriptional changes and cellular effects following modulation of p63 expression, we have defined a vital role for p63 in cellular adhesion. Knockdown of p63 expression caused downregulation of cell adhesion-associated genes, cell detachment and anoikis in mammary epithelial cells and keratinocytes. Conversely, overexpression of the TAp63gamma or deltaNp63alpha isoforms of p63 upregulated cell adhesion molecules, increased cellular adhesion and conferred resistance to anoikis. Apoptosis induced by loss of p63 was rescued by signalling downstream of beta4 integrin. Our results implicate p63 as a key regulator of cellular adhesion and survival in basal cells of the mammary gland and other stratified epithelial tissues.

Anoikis↗
PubMed2006

Estrogen receptor target gene: an evolving concept.

Estrogen receptor (ER) functions as a transcription factor to induce gene expression events sufficient for cell division and breast cancer progression. A significant body of work exists on the identification of ER gene targets and the cofactors that contribute to these transcription events, yet surprisingly little is known of the cis-regulatory elements involved. In this review, we investigate the advances in technology that contribute to a comprehensive understanding of ER target genes and explore recent work identifying cis-regulatory domains that augment transcription of these targets. Specifically, we find that ER association with gene targets results from an association with the pioneer factor FoxA1, responsible for recruitment of ER to the genome. Recruitment of ER to the genome does not occur at promoter proximal regions, but instead involves distal enhancer elements that function to tether the ER complex to the target gene promoters. These advances in technology permit a more detailed investigation of ER activity and may aid in the development of superior drug interventions.

Animals↗
PubMed2006

The marriage moments program for couples transitioning to parenthood: divergent conclusions from formative and outcome evaluation data.

This article presents the results of a pilot study of the Marriage Moments program, designed to prevent relationship deterioration during the 1st year of parenthood. The self-guided, low-intensity program emphasizes strengthening marital virtues and partnership during this time of significant personal and family transition. One hundred fifty-five married couples participated in a randomized clinical trial with 2 psychoeducational treatment groups (a self-guided group and an instructor-encouraged group) and a comparable control group. Despite positive formative evaluation results from program participants, hierarchical linear modeling analyses failed to find significant Group x Time differences on spouses' reports of marital virtues and a set of relational outcome measures. This failure reinforces the need for psychoeducators to invest in outcome evaluation research before claiming program success.

Adult↗
PubMed2005

Spatial and temporal recruitment of androgen receptor and its coactivators involves chromosomal looping and polymerase tracking.

Androgen receptor (AR) plays a critical role in the development and progression of prostate cancer, where it is a key therapeutic target. Here we report that, in contrast to estrogen receptor transcription complexes which form within minutes and recycle hourly, the levels of regulatory regions bound by AR complexes rise over a 16 hr period and then slowly decline. AR regulation of the prostate specific antigen (PSA) gene involves both a promoter-proximal sequence as well as an enhancer approximately 4 kb upstream. Recruitment of AR and its essential coactivators at both sites creates a chromosomal loop that allows RNA polymerase II (pol II) to track from the enhancer to the promoter. Phosphorylation of the pol II C-terminal domain is required for pol II tracking but not chromosomal looping. Development of improved hormonal therapies for prostate cancer must take in account the specific spatial and temporal modes of AR-mediated gene regulation.

Androgens↗
PubMed2005

Chromosome-wide mapping of estrogen receptor binding reveals long-range regulation requiring the forkhead protein FoxA1.

Estrogen plays an essential physiologic role in reproduction and a pathologic one in breast cancer. The completion of the human genome has allowed the identification of the expressed regions of protein-coding genes; however, little is known concerning the organization of their cis-regulatory elements. We have mapped the association of the estrogen receptor (ER) with the complete nonrepetitive sequence of human chromosomes 21 and 22 by combining chromatin immunoprecipitation (ChIP) with tiled microarrays. ER binds selectively to a limited number of sites, the majority of which are distant from the transcription start sites of regulated genes. The unbiased sequence interrogation of the genuine chromatin binding sites suggests that direct ER binding requires the presence of Forkhead factor binding in close proximity. Furthermore, knockdown of FoxA1 expression blocks the association of ER with chromatin and estrogen-induced gene expression demonstrating the necessity of FoxA1 in mediating an estrogen response in breast cancer cells.

Animals↗
PubMed2005

Estrogen and insulin/IGF-1 cooperatively stimulate cell cycle progression in MCF-7 breast cancer cells through differential regulation of c-Myc and cyclin D1.

Estrogen and insulin/insulin-like growth factor-I (IGF-I) are major mitogens for breast epithelial cells and when co-administered, synergistically induce G(1)-S phase cell cycle progression. We investigated this cooperativity by evaluating if the key cell cycle regulators, c-Myc and cyclin D1, represent points of convergence in the action of these mitogens in MCF-7 breast cancer cells. These studies demonstrated that estrogen significantly increased both c-Myc and cyclin D1 protein, while insulin predominantly increased cyclin D1 levels. This cumulative increase in c-Myc and cyclin D1 contributes to the cooperativity of these mitogens, since ectopic expression of c-Myc or cyclin D1 cooperates with either the estrogen or insulin signaling pathways to increase cell cycle progression. Inhibition of the MAPK or PI3-kinase pathways significantly reduced c-Myc and cyclin D1 protein levels and cell cycle progression. Ectopic expression of cyclin D1 partially overcame this inhibition, while ectopic expression of c-Myc partially overcame MAPK but not PI3-kinase inhibition. Therefore, estrogen and insulin/IGF-1 differentially regulate c-Myc and cyclin D1 to cooperatively stimulate breast cancer cell proliferation.

Breast Neoplasms↗
PubMed2003

p27(Kip1) induces quiescence and growth factor insensitivity in tamoxifen-treated breast cancer cells.

Tamoxifen, a selective estrogen-receptor modulator, is effective in the treatment and prevention of breast cancer, but therapeutic resistance is common. Pure steroidal antiestrogens are efficacious in tamoxifen-resistant disease and, unlike tamoxifen, arrest cells in a state of quiescence from which they cannot reenter the cell cycle after growth factor stimulation. We now show that in hydroxytamoxifen-treated cells, transduction of the cell cycle inhibitor p27(Kip1) induces quiescence and insensitivity to growth stimulation by insulin/insulin-like growth factor I and epidermal growth factor/transforming growth factor alpha. Furthermore, reinitiation of cell cycle progression by insulin/insulin-like growth factor I in hydroxytamoxifen-arrested cells involves dissociation of the corepressors nuclear receptor corepressor (N-CoR) and silencing mediator for retinoid and thyroid hormone receptor (SMRT) from nuclear estrogen receptor alpha and redistribution to the cytoplasm, a process that is inhibited by mitogen-activated protein/extracellular signal-regulated kinase, but not phosphatidylinositol 3'-kinase, inhibitors. These data suggest that agents that up-regulate p27(Kip1) or inhibit growth factor signaling via the extracellular signal-regulated kinases should be tested as therapeutic strategies in tamoxifen-resistant breast cancer.

Breast Neoplasms↗
PubMed2003

Contrasting effects of prenyltransferase inhibitors on estrogen-dependent cell cycle progression and estrogen receptor-mediated transcriptional activity in MCF-7 cells.

Activation of estrogen receptors (ERs) by estrogens triggers both ER nuclear transcriptional activity and Src/Ras/Erks pathway-dependent mitogenic activity. The present study implicates prenylated proteins in both estrogenic actions. The farnesyltransferase and geranylgeranyltransferase I inhibitors (FTI-277 and GGTI-298, respectively) antagonize estradiol-stimulated cell cycle progression, progesterone receptor, cyclin D1, and c-Myc expression. In contrast, the inhibitors markedly stimulate transcription from two genes containing estrogen response elements, both in the absence and presence of estradiol. The pure antiestrogen ICI 182,780 inhibits by more than 85% these effects on transcription. We demonstrate that both FTI-277 and GGTI-298 increase the association of steroid receptor coactivator-1 with ER alpha and FTI-277 decreases the association of ER alpha with the histone deacetylase 1, a known transcriptional repressor. In addition, FTI-277 has no marked effect on the association of the two corepressors, nuclear receptor corepressor and silencing mediator of retinoid and thyroid receptor with ER alpha, whereas GGTI-298, similar to tamoxifen, clearly increased these associations. Together, these results demonstrate that prenylated proteins play a role in estradiol stimulation of proliferation and progesterone receptor expression. However, they antagonize the ability of ER alpha to stimulate estrogen response element-dependent transcriptional activity, acting presumably through coregulator complex formation.

Alkyl and Aryl Transferases↗
PubMed2002

Constitutive overexpression of cyclin D1 but not cyclin E confers acute resistance to antiestrogens in T-47D breast cancer cells.

Cyclin D1 and cyclin E are overexpressed in approximately 45% and 30% of breast cancers, respectively, and adverse associations with patient outcome have been reported. The potential roles of cyclin D1 and cyclin E expression as markers of therapeutic responsiveness to the pure steroidal antiestrogen ICI 182780 were investigated using T-47D breast cancer cell lines constitutively overexpressing cyclin D1 or cyclin E. Measurement of S phase fraction, phosphorylation states of the retinoblastoma protein, and cyclin E-cyclin-dependent kinase (Cdk) 2 activity demonstrated that overexpression of cyclin D1 decreased sensitivity to antiestrogen inhibition at 24 and 48 h. Overexpression of cyclin E produced a less pronounced early cell cycle effect indicating only partial resistance to antiestrogen inhibition in the short-term. In ICI 182780-treated cyclin D1-overexpressing cells, sufficient Cdk activity was retained to allow retinoblastoma protein phosphorylation and cell proliferation, despite an increase in the association of p21 and p27 with cyclin D1-Cdk4/6 and cyclin E-Cdk2 complexes. After longer-term (>7 days) treatment, antiestrogens inhibited colony growth in cyclin D1- or cyclin E-overexpressing breast cancer cells, but with an approximately 2-2.5-fold decrease in dose sensitivity. This was associated with a fall in cyclin D1 levels, a reduction in the half-life of cyclin D1 protein and a decline in cyclin E-Cdk2 activity in cyclin D1-overexpressing cells, and the maintenance of cyclin E-p27 association in the cyclin E-overexpressing cells. These data confirm that cyclin D1 expression and cyclin E-p27 association play important roles in antiestrogen action, and suggest that cyclin D1 or cyclin E overexpression has subtle effects on antiestrogen sensitivity. Additional studies to elucidate the contribution of alterations in cyclin D1 stability to antiestrogen action and to assess the relationship between antiestrogen sensitivity and expression of cyclin D1, cyclin E, or p27 in a clinical setting are required.

Breast Neoplasms↗
PubMed2002

Mechanisms of growth arrest by c-myc antisense oligonucleotides in MCF-7 breast cancer cells: implications for the antiproliferative effects of antiestrogens.

The proto-oncogene c-myc is up-regulated by estrogen stimulation of hormone-dependent breast cancer cells and is frequently overexpressed in breast and other cancers. Therapeutic interventions that inhibit c-Myc expression have been extensively investigated, including antisense oligonucleotides that have high specificity and potential clinical application. This investigation compared antiestrogen-mediated growth arrest with the molecular events after repression of c-Myc expression in MCF-7 breast cancer cells using an antisense oligonucleotide. We show that the decreased cellular proliferation of MCF-7 cells after direct inhibition of c-Myc is a consequence of inhibition of cyclin D1 expression, subsequent redistribution of p21(WAF1/CIP1) from cyclin D1-Cdk4 to cyclin E-Cdk2 complexes, and a decline in cyclin E-Cdk2 enzymatic activity. Simultaneous repression of p21(WAF1/CIP1) can attenuate the growth-inhibitory effects of reduced c-Myc expression emphasizing the importance of this cyclin-dependent kinase (CDK) inhibitor in growth arrest. These molecular events are similar to the initial changes in cyclin gene expression, CDK complex formation and CDK activity seen after antiestrogen (ICI 182780)-mediated growth inhibition of MCF-7 cells, which suggests that the down-regulation of c-Myc by ICI 182780 is a primary event that culminates in cell cycle arrest.

Breast Neoplasms↗
PubMed2002

The Families and Democracy Project.

The Families and Democracy Project moves family therapists and other professionals into the community via a critique of traditional provider/consumer models of family services, a set of principles about the civic engagement of families in partnership with professionals, and a set of public practices for working on community problems. We describe the Families and Democracy model and three specific projects. We distinguish the model from traditional hierarchical and collaborative models of working with families. And we discuss lessons we have learned, and our plans to take this work to its next developmental stage.

Adolescent↗