Michael L Whitfield

Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States

Are you Michael L Whitfield?

Claim your profile

Publications (52)323.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective. Accumulation of myofibroblasts in the fibrotic skin is a hallmark of systemic sclerosis (SSc), but the origins of these cells remain unknown. Since loss of intradermal adipose tissue is a consistent feature of cutaneous fibrosis, we sought to examine the hypothesis that myofibroblasts populating fibrotic dermis derive from adipocytic progenitors.Methods. Loss of intradermal adipose tissue and its potential role in fibrosis was investigated in mice with bleomycin-induced scleroderma by genetic fate mapping. Modulation of adipocytic phenotypes ex vivo was investigated in adipose-derived cells in culture.Results. Striking loss of intradermal adipose and its replacement with fibrous tissue was consistently observed during bleomycin-induced fibrosis. Loss of adipose and decline in expression of canonical adipogenic markers in the lesional skin preceded the onset of dermal fibrosis and expression of fibrogenic markers. Ex vivo, subcutaneous adipocytes were driven to preferentially undergo fibrogenic differentiation by transforming growth factor-ß. Cell fate-mapping studies using transgenic mice with adiponectin promoter driving Cre recombinase to specifically label mature adipocytes indicated that adiponectin-positive progenitors that are normally confined to the intradermal adipose compartment distributed throughout the lesional dermis over time, lost their adipocytic markers and expressed myofibroblast markers, in bleomycin-treated mice.Conclusions. These observations establish a novel link between intradermal adipose loss and dermal fibrosis, and demonstrate that adiponectin-positive intradermal progenitors give rise to dermal myofibroblasts. Adipose loss and adipocyte-myofibroblast transition might be primary events in the pathogenesis of cutaneous fibrosis that represent novel potential targets for anti-fibrotic intervention. This article is protected by copyright. All rights reserved.
    Arthritis & Rheumatology. 12/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Systemic sclerosis (SSc) is a polygenic, autoimmune disorder of unknown etiology, characterized by the excessive accumulation of extracellular matrix (ECM) proteins, vascular alterations, and autoantibodies. The tight skin (Tsk)2/+ mouse model of SSc demonstrates signs similar to SSc including tight skin and excessive deposition of dermal ECM proteins. By linkage analysis, we mapped the Tsk2 gene mutation to less than 3 megabases on chromosome 1. We performed both RNA sequencing of skin transcripts and genome capture DNA sequencing of the region spanning this interval in Tsk2/+ and wild-type littermates. A missense point mutation in the procollagen III amino terminal propeptide segment (PIIINP) of Col3a1 was found to be the best candidate for Tsk2, so both in vivo and in vitro genetic complementation tests were used to prove that this Col3a1 mutation is the Tsk2 gene. All previously documented mutations in the human Col3a1 gene are associated with Ehlers-Danlos syndrome, a connective tissue disorder that leads to a defect in type III collagen synthesis. To our knowledge, the Tsk2 point mutation is the first documented gain-of-function mutation associated with Col3a1, which leads instead to fibrosis. This discovery provides insight into the mechanism of skin fibrosis manifested by Tsk2/+ mice.Journal of Investigative Dermatology accepted article preview online, 20 October 2014. doi:10.1038/jid.2014.455.
    The Journal of investigative dermatology. 10/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous studies have suggested a role for pathogens as a trigger of systemic sclerosis (SSc), though neither a pathogen nor a mechanism of pathogenesis is known. Here we show enrichment of Rhodotorula sequences in the skin of patients with early, diffuse SSc compared to normal controls. RNA-seq was performed on four SSc and four controls, to a depth of 200 million reads per patient. Data were analyzed to quantify the non-human sequence reads in each sample. We found little difference between bacterial microbiome and viral read counts, but found a significant difference between the read counts for a mycobiome component, R. glutinis. Normal samples contained almost no detected R. glutinis or other Rhodotorula sequence reads (mean score 0.021 for R. glutinis, 0.024 for all Rhodotorula). In contrast, SSc samples had a mean score of 5.039 for R. glutinis (5.232 for Rhodotorula). We were able to assemble the D1-D2 hypervariable region of the 28 S rRNA of R. glutinis from each of the SSc samples. Taken together, these results suggest R. glutinis may be present in the skin of early SSc patients at higher levels than normal skin, raising the possibility that it may be triggering the inflammatory response found in SSc.Journal of Investigative Dermatology accepted article preview online, 7 March 2014; doi:10.1038/jid.2014.127.
    Journal of Investigative Dermatology 03/2014; · 6.19 Impact Factor
  • Michael L. Whitfield
    Arthritis & Rheumatology. 01/2014; 66(1).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We identified the cell cycle-regulated mRNA transcripts genome-wide in the osteosarcoma derived U2OS cell line. This resulted in 2140 transcripts mapping to 1871 unique cell cycle-regulated genes that show periodic oscillations across multiple synchronous cell cycles. We identified genomic loci bound by the G2/M transcription factor FOXM1 by Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) and associated these with cell cycle-regulated genes. FOXM1 was bound to cell cycle-regulated genes with peak expression in both S phase and G2/M phases. ChIP-seq genomic loci were shown to be responsive to FOXM1 using a real-time luciferase assay in live cells, showing that FOXM1 strongly activates promoters of G2/M phase genes and weakly activates those induced in S phase. Analysis of ChIP-seq data from a panel of cell cycle-transcription factors (E2F1, E2F4, E2F6, and GABPA) from ENCODE and ChIP-seq data for the DREAM complex, found that a set of core cell cycle genes regulated in both U2OS and HeLa cells are bound by multiple cell cycle transcription factors. These data identify the cell cycle-regulated genes in a second cancer derived cell line and provide a comprehensive picture of the transcriptional regulatory systems controlling periodic gene expression in the human cell division cycle.
    Molecular biology of the cell 10/2013; · 5.98 Impact Factor
  • Source
    Chao Cheng, Matthew Ung, Gavin D Grant, Michael L Whitfield
    [Show abstract] [Hide abstract]
    ABSTRACT: Cell cycle is a complex and highly supervised process that must proceed with regulatory precision to achieve successful cellular division. Despite the wide application, microarray time course experiments have several limitations in identifying cell cycle genes. We thus propose a computational model to predict human cell cycle genes based on transcription factor (TF) binding and regulatory motif information in their promoters. We utilize ENCODE ChIP-seq data and motif information as predictors to discriminate cell cycle against non-cell cycle genes. Our results show that both the trans- TF features and the cis- motif features are predictive of cell cycle genes, and a combination of the two types of features can further improve prediction accuracy. We apply our model to a complete list of GENCODE promoters to predict novel cell cycle driving promoters for both protein-coding genes and non-coding RNAs such as lincRNAs. We find that a similar percentage of lincRNAs are cell cycle regulated as protein-coding genes, suggesting the importance of non-coding RNAs in cell cycle division. The model we propose here provides not only a practical tool for identifying novel cell cycle genes with high accuracy, but also new insights on cell cycle regulation by TFs and cis-regulatory elements.
    PLoS Computational Biology 07/2013; 9(7):e1003132. · 4.87 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective Pulmonary arterial hypertension (PAH), a common complication of limited cutaneous systemic sclerosis (lcSSc), is associated with alterations of markers of inflammation and vascular damage in peripheral blood mononuclear cells (PBMCs). Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) have been implicated in autoimmune and inflammatory diseases. The goal of this study was to assess whether markers of ER stress and the UPR are present in PBMCs from lcSSc patients with PAH. MethodsPBMCs were purified from 36 healthy controls, 32 lcSSc patients with PAH, and 34 lcSSc patients without PAH. Gene expression in healthy control PBMCs stimulated with thapsigargin was analyzed by DNA microarray. Genes were validated by quantitative real-time reverse transcription–polymerase chain reaction in PBMCs from healthy controls and lcSSc patients. ResultsSeveral ER stress/UPR genes, including BiP, activating transcription factor 4 (ATF-4), ATF-6, and a spliced form of X-box binding protein 1, were up-regulated in PBMCs from lcSSc patients, with the highest levels in patients with PAH. Thapsigargin up-regulated heat-shock proteins (HSPs) and interferon (IFN)–regulated genes in PBMCs from healthy controls. Selected HSP genes (particularly DnaJB1) and IFN-related genes were also found at significantly elevated levels in PBMCs from lcSSc patients, while IFN regulatory factor 4 expression was significantly decreased. There was a positive correlation between DnaJB1 and severity of PAH (measured by pulmonary artery pressure) (r = 0.56, P < 0.05) and between ER stress markers and interleukin-6 levels (r = 0.53, P < 0.0001) in PBMCs from lcSSc patients. Conclusion This study demonstrates an association between select ER stress/UPR markers and lcSSc with PAH, suggesting that ER stress and the UPR may contribute to the altered function of circulating immune cells in lcSSc.
    Arthritis & Rheumatology 05/2013; 65(5). · 7.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Heterogeneity in systemic sclerosis (SSc) confounds clinical trials. We previously identified "intrinsic" gene expression subsets by analysis of SSc skin. Here we test the hypotheses that skin gene expression signatures including intrinsic subset are associated with modified Rodnan skin score (MRSS) improvement during mycophenolate mofetil (MMF) treatment. Gene expression and intrinsic subset assignment were measured in 12 SSc patients' biopsies and 10 controls at baseline, and from serial biopsies of 1 cyclophosphamide-treated patient and 9 MMF-treated patients. Gene expression changes during treatment were determined using paired t-tests corrected for multiple hypothesis testing. MRSS improved in four of seven MMF-treated patients classified as the inflammatory intrinsic subset. Three patients without MRSS improvement were classified as normal-like or fibroproliferative intrinsic subsets. A total of 321 genes (false discovery rate (FDR)<5%) were differentially expressed at baseline between patients with and without MRSS improvement during treatment. The expression of 571 genes (FDR<10%) changed between pre- and post-MMF treatment biopsies for patients showing MRSS improvement. Gene expression changes in skin are only seen in patients with MRSS improvement. Baseline gene expression in skin, including intrinsic subset assignment, may identify SSc patients whose MRSS will improve during MMF treatment, suggesting that gene expression in skin may allow targeted treatment in SSc.Journal of Investigative Dermatology advance online publication, 16 May 2013; doi:10.1038/jid.2013.130.
    Journal of Investigative Dermatology 03/2013; · 6.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We developed a system to monitor periodic luciferase activity from cell cycle-regulated promoters in synchronous cells. Reporters were driven by a minimal human E2F1 promoter with peak expression in G1/S or a basal promoter with six Forkhead DNA-binding sites with peak expression at G2/M. After cell cycle synchronization, luciferase activity was measured in live cells at 10-min intervals across three to four synchronous cell cycles, allowing unprecedented resolution of cell cycle-regulated gene expression. We used this assay to screen Forkhead transcription factors for control of periodic gene expression. We confirmed a role for FOXM1 and identified two novel cell cycle regulators, FOXJ3 and FOXK1. Knockdown of FOXJ3 and FOXK1 eliminated cell cycle-dependent oscillations and resulted in decreased cell proliferation rates. Analysis of genes regulated by FOXJ3 and FOXK1 showed that FOXJ3 may regulate a network of zinc finger proteins and that FOXK1 binds to the promoter and regulates DHFR, TYMS, GSDMD, and the E2F binding partner TFDP1. Chromatin immunoprecipitation followed by high-throughput sequencing analysis identified 4329 genomic loci bound by FOXK1, 83% of which contained a FOXK1-binding motif. We verified that a subset of these loci are activated by wild-type FOXK1 but not by a FOXK1 (H355A) DNA-binding mutant.
    Molecular biology of the cell 06/2012; 23(16):3079-93. · 5.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Progressive fibrosis in systemic sclerosis (SSc) is linked to aberrant transforming growth factor beta (TGF-beta) signaling. Peroxisome proliferator-activated receptor gamma (PPAR-gamma) blocks fibrogenic TGF-beta responses in vitro and in vivo. Reduced expression and function of PPAR-gamma in patients with SSc may contribute to progression of fibrosis. Here we evaluated the levels of adiponectin, a sensitive and specific index of PPAR-gamma activity, as a potential fibrogenic biomarker in SSc. Adiponectin levels were determined in the sera of 129 patients with SSc and 86 healthy controls, and serial determinations were performed in 27 patients. Levels of adiponectin mRNA in skin biopsies from SSc patients were assessed in an expression profiling microarray dataset. Regulation of adiponectin gene expression in explanted human subcutaneous preadipocytes and fibroblasts was examined by real-time quantitative PCR. Patients with diffuse cutaneous SSc had reduced serum adiponectin levels. A significant inverse correlation between adiponectin levels and the modified Rodnan skin score was observed. In longitudinal studies changes in serum adiponectin levels were inversely correlated with changes in skin fibrosis. Skin biopsies from a subset of SSc patients showed reduced adiponectin mRNA expression which was inversely correlated with the skin score. An agonist ligand of PPAR-gamma potently induced adiponectin expression in explanted mesenchymal cells in vitro. Levels of adiponectin, reflecting PPAR-gamma activity, are correlated with skin fibrosis and might have potential utility as a biomarker in SSc.
    Arthritis research & therapy 05/2012; 14(3):R102. · 4.27 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Development of personalized treatment regimens is hampered by lack of insight into how individual animal models reflect subsets of human disease, and autoimmune and inflammatory conditions have proven resistant to such efforts. Scleroderma is a lethal autoimmune disease characterized by fibrosis, with no effective therapy. Comparative gene expression profiling showed that murine sclerodermatous graft-versus-host disease (sclGVHD) approximates an inflammatory subset of scleroderma estimated at 17% to 36% of patients analyzed with diffuse, 28% with limited, and 100% with localized scleroderma. Both sclGVHD and the inflammatory subset demonstrated IL-13 cytokine pathway activation. Host dermal myeloid cells and graft T cells were identified as sources of IL-13 in the model, and genetic deficiency of either IL-13 or IL-4Rα, an IL-13 signal transducer, protected the host from disease. To identify therapeutic targets, we explored the intersection of genes coordinately up-regulated in sclGVHD, the human inflammatory subset, and IL-13-treated fibroblasts; we identified chemokine CCL2 as a potential target. Treatment with anti-CCL2 antibodies prevented sclGVHD. Last, we showed that IL-13 pathway activation in scleroderma patients correlated with clinical skin scores, a marker of disease severity. Thus, an inflammatory subset of scleroderma is driven by IL-13 and may benefit from IL-13 or CCL2 blockade. This approach serves as a model for personalized translational medicine, in which well-characterized animal models are matched to molecularly stratified patient subsets.
    American Journal Of Pathology 03/2012; 180(3):1080-94. · 4.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Fibrosis in human diseases and animal models is associated with aberrant Wnt/β-catenin pathway activation. The aim of this study was to characterize the regulation, activity, mechanism of action, and significance of Wnt/β-catenin signaling in the context of systemic sclerosis (SSc). The expression of Wnt signaling pathway components in SSc skin biopsy specimens was analyzed. The regulation of profibrotic responses by canonical Wnt/β-catenin was examined in explanted human mesenchymal cells. Fibrotic responses were studied using proliferation, migration, and gel contraction assays. The cell fate specification of subcutaneous preadipocytes by canonical Wnt signaling was evaluated. Analysis of published genome-wide expression data revealed elevated expression of the Wnt receptor FZD2 and the Wnt target LEF1 and decreased expression of Wnt antagonists DKK2 and WIF1 in skin biopsy specimens from subsets of patients with diffuse cutaneous SSc compared to the other distinct subsets. Immunohistochemical analysis showed increased nuclear β-catenin expression in these biopsy specimens. In vitro, Wnt-3a induced β-catenin activation, stimulated fibroblast proliferation and migration, collagen gel contraction, and myofibroblast differentiation, and enhanced profibrotic gene expression. Genetic and pharmacologic approaches were used to demonstrate that these profibrotic responses involved autocrine transforming growth factor β signaling via Smads. In contrast, in explanted subcutaneous preadipocytes, Wnt-3a repressed adipogenesis and promoted myofibroblast differentiation. Canonical Wnt signaling was hyperactivated in SSc skin biopsy specimens. In explanted mesenchymal cells, Wnt-3a stimulated fibrogenic responses while suppressing adipogenesis. Taken together, these results indicate that Wnts have potent profibrotic effects, and that canonical Wnt signaling plays an important role in the pathogenesis of fibrosis and lipoatrophy in SSc.
    Arthritis & Rheumatology 02/2012; 64(8):2734-45. · 7.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Skin biopsy gene expression was analyzed by DNA microarray from 13 diffuse cutaneous systemic sclerosis (dSSc) patients enrolled in an open-label study of rituximab, 9 dSSc patients not treated with rituximab, and 9 healthy controls. These data recapitulate the patient "intrinsic" gene expression subsets described previously, including fibroproliferative, inflammatory, and normal-like groups. Serial skin biopsies showed consistent and non-progressing gene expression over time, and importantly, the patients in the inflammatory subset do not move to the fibroproliferative subset, and vice versa. We were unable to detect significant differences in gene expression before and after rituximab treatment, consistent with an apparent lack of clinical response. Serial biopsies from each patient stayed within the same gene expression subset, regardless of treatment regimen or the time point at which they were taken. Collectively, these data emphasize the heterogeneous nature of SSc and demonstrate that the intrinsic subsets are an inherent, reproducible, and stable feature of the disease that is independent of disease duration. Moreover, these data have fundamental importance for the future development of personalized therapy for SSc; drugs targeting inflammation are likely to benefit those patients with an inflammatory signature, whereas drugs targeting fibrosis are likely to benefit those with a fibroproliferative signature.
    Journal of Investigative Dermatology 02/2012; 132(5):1363-73. · 6.19 Impact Factor
  • Source
    Jennifer L Sargent, Michael L Whitfield
    [Show abstract] [Hide abstract]
    ABSTRACT: Heterogeneity in the clinical presentation and basic science findings of systemic sclerosis (SSc) has hindered the understanding of pathogenesis and development of effective treatments. Genome-wide profiling of SSc has measured this heterogeneity. Gene expression studies of diffuse SSc skin have shown reproducible, disease-specific gene expression signatures when compared with healthy controls and, surprisingly, disease-specific gene expression was found in both lesional and non-lesional skin. SSc-specific gene expression in peripheral blood cells and the lungs has also been demonstrated. Hypothesis-driven approaches that assess the contribution of individual pathways provide insight into the etiology of gene expression subsets.
    Expert Review of Clinical Immunology 07/2011; 7(4):463-73. · 2.89 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Eosinophilia-myalgia syndrome (EMS) is characterized by subacute onset of myalgias and peripheral eosinophilia, followed by chronic neuropathy and skin induration. An epidemic of EMS in 1989 was linked to consumption of L-tryptophan that had originated from a single source. Following the ban by the Food and Drug Administration (FDA) on the sale of L-tryptophan, the incidence of EMS declined rapidly. Moreover, no new cases have been described since the FDA ban was lifted in 2005. We report the clinical, histopathologic, and immunogenetic features of a new case of L-tryptophan-associated EMS, along with evidence of activated transforming growth factor β and interleukin-4 signaling in the lesional skin.
    Arthritis & Rheumatology 06/2011; 63(11):3633-9. · 7.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To explore the relationship between biomarkers of pulmonary arterial hypertension (PAH), interferon (IFN)-regulated gene expression, and the alternative activation pathway in systemic sclerosis (SSc). Peripheral blood mononuclear cells (PBMCs) were purified from healthy controls, patients with idiopathic PAH, and SSc patients (classified as having diffuse cutaneous SSc, limited cutaneous SSc [lcSSc] without PAH, and lcSSc with PAH). IFN-regulated and "PAH biomarker" genes were compared after supervised hierarchical clustering. Messenger RNA levels of selected IFN-regulated genes (Siglec1 and MX1), biomarker genes (IL13RA1, CCR1, and JAK2), and the alternative activation marker gene (MRC1) were analyzed on PBMCs and on CD14- and CD14+ cell populations. Interleukin-13 (IL-13) and IL-4 concentrations were measured in plasma by immunoassay. CD14, MRC1, and IL13RA1 surface expression was analyzed by flow cytometry. Increased PBMC expression of both IFN-regulated and biomarker genes distinguished SSc patients from healthy controls. Expression of genes in the biomarker cluster, but not in the IFN-regulated cluster, distinguished lcSSc with PAH from lcSSc without PAH. The genes CCR1 (P<0.001) and JAK2 (P<0.001) were expressed more highly in lcSSc patients with PAH compared with controls and mainly by CD14+ cells. MRC1 expression was increased exclusively in lcSSc patients with PAH (P<0.001) and correlated strongly with pulmonary artery pressure (r=0.52, P=0.03) and higher mortality (P=0.02). MRC1 expression was higher in CD14+ cells and was greatly increased by stimulation with IL-13. IL-13 concentrations in plasma were most highly increased in lcSSc patients with PAH (P<0.001). IFN-regulated and biomarker genes represent distinct, although related, clusters in lcSSc patients with PAH. MRC1, a marker for the effect of IL-13 on alternative monocyte/macrophage activation, is associated with this severe complication and is related to mortality.
    Arthritis & Rheumatology 03/2011; 63(6):1718-28. · 7.48 Impact Factor
  • Tamiko R Katsumoto, Michael L Whitfield, M Kari Connolly
    [Show abstract] [Hide abstract]
    ABSTRACT: Systemic sclerosis (SSc), also known as scleroderma, is a rare connective tissue disease characterized by vascular and immune dysfunction, leading to fibrosis that can damage multiple organs. Its pathogenesis is complex and poorly understood. Two major clinical subtypes are the limited and diffuse forms. Research into SSc has been hampered by its rarity, its clinical heterogeneity, and the lack of mouse models that accurately recapitulate the disease. Clinical and basic studies have yielded some mechanistic clues regarding pathogenesis. Recent insights gained through the use of microarrays have revealed distinctive subsets of SSc within and beyond the limited and diffuse subsets. In this review, we discuss potential mechanisms underlying the vascular, autoimmune, and fibrotic points of dysregulation. Proper categorization of SSc patients for research studies by use of microarrays or other biomarkers is critical, as disease heterogeneity may explain some of the inconsistencies of prior studies.
    Annual Review of Pathology Mechanisms of Disease 02/2011; 6:509-37. · 25.79 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Transforming growth factor-ß (TGF-ß) signaling is implicated in the pathogenesis of fibrosis in scleroderma or systemic sclerosis (SSc), but the precise mechanisms are poorly understood. The immediate-early gene Egr-1 is an inducible transcription factor with key roles in mediating fibrotic TGF-ß responses. To elucidate Egr-1 function in SSc-associated fibrosis, we examined change in gene expression induced by Egr-1 in human fibroblasts at the genome-wide level. Using microarray expression analysis, we derived a fibroblast "Egr-1-responsive gene signature" comprising over 600 genes involved in cell proliferation, TGF-ß signaling, wound healing, extracellular matrix synthesis and vascular development. The experimentally derived "Egr-1-responsive gene signature" was then evaluated in an expression microarray dataset comprising skin biopsies from 27 patients with localized and systemic forms of scleroderma and six healthy controls. We found that the "Egr-1 responsive gene signature" was substantially enriched in the "diffuse-proliferation" subset comprising exclusively of patients with diffuse cutaneous SSc (dcSSc) of skin biopsies. A number of Egr-1-regulated genes was also associated with the "inflammatory" intrinsic subset. Only a minority of Egr-1-regulated genes was concordantly regulated by TGF-ß. These results indicate that Egr-1 induces a distinct profibrotic/wound healing gene expression program in fibroblasts that is associated with skin biopsies from SSc patients with diffuse cutaneous disease. These observations suggest that targeting Egr-1 expression or activity might be a novel therapeutic strategy to control fibrosis in specific SSc subsets.
    PLoS ONE 01/2011; 6(9):e23082. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Transcription of long noncoding RNAs (lncRNAs) within gene regulatory elements can modulate gene activity in response to external stimuli, but the scope and functions of such activity are not known. Here we use an ultrahigh-density array that tiles the promoters of 56 cell-cycle genes to interrogate 108 samples representing diverse perturbations. We identify 216 transcribed regions that encode putative lncRNAs, many with RT-PCR-validated periodic expression during the cell cycle, show altered expression in human cancers and are regulated in expression by specific oncogenic stimuli, stem cell differentiation or DNA damage. DNA damage induces five lncRNAs from the CDKN1A promoter, and one such lncRNA, named PANDA, is induced in a p53-dependent manner. PANDA interacts with the transcription factor NF-YA to limit expression of pro-apoptotic genes; PANDA depletion markedly sensitized human fibroblasts to apoptosis by doxorubicin. These findings suggest potentially widespread roles for promoter lncRNAs in cell-growth control.
    Nature Genetics 01/2011; 43(7):621-9. · 35.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Abnormal fibrillinogenesis is associated with connective tissue disorders (CTDs), including Marfan syndrome (MFS), systemic sclerosis (SSc) and Tight-skin (Tsk) mice. We have previously shown that TGF-beta and Wnt stimulate fibrillin-1 assembly and that fibrillin-1 and the developmental regulator CCN3 are both highly increased in Tsk skin. We investigated the role of CCN3 in abnormal fibrillinogenesis in Tsk mice, MFS, and SSc. Smad3 deletion in Tsk mice decreased CCN3 overexpression, suggesting that TGF-beta mediates at least part of the effect of Tsk fibrillin on CCN3 which is consistent with a synergistic effect of TGF-beta and Wnt in vitro on CCN3 expression. Disruption of fibrillin-1 assembly by MFS fibrillin decreased CCN3 expression and skin from patients with early diffuse SSc showed a strong correlation between increased CCN3 and fibrillin-1 expression, suggesting that CCN3 regulation by fibrillin-1 extends to these CTDs. Diffuse SSc skin and sera also showed evidence of increased Wnt activity, implicating a Wnt stimulus behind this correlation. CCN3 overexpression markedly repressed fibrillin-1 assembly and also blocked other TGFbeta- and Wnt-regulated profibrotic gene expression. Together, these data indicate that CCN3 counter-regulates positive signals from TGF-beta and Wnt for fibrillin fibrillogenesis and profibrotic gene expression.
    Journal of Investigative Dermatology 02/2010; 130(6):1514-23. · 6.19 Impact Factor

Publication Stats

3k Citations
323.67 Total Impact Points


  • 2006–2014
    • Geisel School of Medicine at Dartmouth
      • Department of Genetics
      Hanover, New Hampshire, United States
    • Princeton University
      • Department of Molecular Biology
      Princeton, New Jersey, United States
  • 2011–2013
    • University of Illinois at Chicago
      • Section of Rheumatology
      Chicago, IL, United States
    • University of Massachusetts Boston
      Boston, Massachusetts, United States
  • 2012
    • Ljubljana University Medical Centre
      • Department of Rheumatology
      Lubliano, Ljubljana, Slovenia
  • 2009–2012
    • Northwestern University
      • Feinberg School of Medicine
      Evanston, IL, United States
  • 2010
    • Boston University
      • Section of Rheumatology
      Boston, MA, United States
    • Dartmouth College
      Hanover, New Hampshire, United States
  • 2005
    • Stanford Medicine
      Stanford, California, United States
  • 2004
    • Howard Hughes Medical Institute
      Ashburn, Virginia, United States
  • 1995–2004
    • University of North Carolina at Chapel Hill
      • Department of Biochemistry and Biophysics
      Chapel Hill, NC, United States
  • 2003
    • University of California, San Francisco
      • Department of Dermatology
      San Francisco, CA, United States