Survivin in the human hair follicle.
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Epidermis↗
Biomedical subjects
Michael Kahn
Publications and source records attributed to Michael Kahn.
A clinico-pathologic correlation. Aggressive fibromatosis and peripheral ossifying fibroma.
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Diagnosis, Differential↗
A clinico-pathologic correlation. Synovial chondromatosis.
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Adult↗
Investigating Wnt signaling: a chemogenomic safari.
Chemical genomics is a powerful method to complement more traditional genetic techniques (i.e. knockout mice, siRNA) for the dissection of complex signaling networks. Wnt signaling in mammals is a complex and crucial regulator of diverse functions. The Wnt-beta-catenin pathway initiates a signaling cascade that is crucial in both normal development and the initiation and progression of cancer. A key step in Wnt activation of target genes is the nuclear translocation of beta-catenin and the formation of a complex between beta-catenin and members of the T-cell factor (TCF) family of transcription factors. Using a forward chemical genomics strategy, we identified ICG-001, a selective inhibitor of a subset of Wnt-beta-catenin-driven gene expression. This chemogenomic tool enables us to dissect this complex signaling network and to better understand the role of Wnt signaling in both normal and pathophysiological settings.
Animals↗
Specific inhibition of CBP/beta-catenin interaction rescues defects in neuronal differentiation caused by a presenilin-1 mutation.
Wnt/beta-catenin signaling has been shown to promote self-renewal in a variety of tissue stem cells, including neuronal stem cells and hematopoietic stem cells. However, activation of the Wnt/beta-catenin pathway promoted and inhibition of the pathway prevented differentiation of neuronal precursor cells. A clear explanation for the differential effects of Wnt/beta-catenin activation on neuronal precursors is not available at present. Presenilin-1 (PS-1) is a polytopic protein comprised of six to eight transmembrane domains. PS-1, as part of the gamma-secretase complex, is required for the intramembrane proteolysis of both amyloid precursor protein (APP) and Notch. Additionally, through interactions with beta-catenin, PS-1 is associated with modulation of Wnt/beta-catenin signaling. A familial Alzheimer's disease-associated PS-1 mutant, PS-1(L286V), causes a dramatic increase in T cell factor (TCF)/beta-catenin transcription in PC-12 cells, which prevents normal nerve growth factor (NGF)-induced neuronal differentiation and neurite outgrowth. Selective inhibition of TCF/beta-catenin/cAMP-response element-binding protein (CREB)-binding protein (CBP)-mediated transcription, but not TCF/beta-catenin/p300, with the recently described small molecule antagonist ICG-001 corrects these defects in neuronal differentiation, highlighting the importance of Wnt/beta-catenin signaling in this process. We propose that increased TCF/beta-catenin/CBP-mediated transcription, as well as a failure to switch to TCF/beta-catenin/p300-mediated transcription, play an important role in decreasing neuronal differentiation.
Animals↗
Differential roles for the coactivators CBP and p300 on TCF/beta-catenin-mediated survivin gene expression.
The inhibitor of apoptosis (IAP) protein survivin is highly expressed in cancers, but not in normal differentiated tissues. TCF/beta-catenin signaling has been reported to participate in the regulation of survivin transcription in colon cancer. We have recently characterized ICG-001, a small molecule specific inhibitor of the beta-catenin/Creb-binding protein (CBP) interaction. Inhibition of the beta-catenin/CBP interaction represses a subset of TCF/beta-catenin-mediated transcription. ICG-001 potently inhibits survivin gene transcription and expression. ICG-001-mediated downregulation of survivin expression enhanced caspase-3 activity and apoptosis, which was rescued by overexpression of wild type but not mutant (C84A) survivin. Small interfering RNA and genetic reduction of CBP also decreased survivin expression. Chromatin immunoprecipitation assay confirmed that CBP is the crucial coactivator for TCF/beta-catenin-mediated survivin transcription. Furthermore, ICG-001-induced recruitment of p300 to the survivin promoter led to concomitant recruitment of SUMO-1, HDAC6 and PML proteins, which have been associated with transcriptional repression. These findings demonstrate that CBP and p300 play very distinct roles in survivin gene transcription.
Animals↗
NF-kappaB plays a major role during the systemic and local acute inflammatory response following intestinal reperfusion injury.
1 The nuclear translocation of transcription factors may be a critical factor in the intracellular pathway involved in ischaemia/reperfusion (I/R) injury. Here, we examined whether NF-kappaB and AP-1 participated in the cascade of events leading to TNF-alpha production, neutrophil recruitment, tissue injury and lethality following intestinal I/R. 2 The superior mesenteric artery (SMA) of mice was made ischaemic for 60 min followed by 30 min of reperfusion. The effects of NF-kappaB and AP-1 were studied by the administration of the thioredoxin inhibitor, MOL-294 (methyl 4-hydroxy-4-(8-methyl-1,3-dioxo-2-phenyl-2,3,5,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]pyridazin-5-yl)but-2-ynoate), and the AP-1 inhibitor, PNRI-299 (N-benzyl-2-(3-cyanophenyl)-1,3,7-trioxo-2,3,7,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]pyridazine-5-carboxamide). After I/R, there was increase of translocation of NF-kappaB, but not of AP-1, in the intestine and lungs, as assessed by a gel shift assay. 3 Treatment with MOL-294 inhibited the increase in vascular permeability, neutrophil accumulation, hemorrhage and proinflammatory cytokine levels, induced by intestinal I/R injury in the intestine. In the lungs, MOL-294 partially inhibited edema formation, TNF-alpha production, but did not alter neutrophil recruitment. 4 Treatment with MOL-294 inhibited reperfusion-associated lethality, an effect likely to be secondary to the inhibition of systemic TNF-alpha levels. PNRI-299 had no effects on the inflammatory changes or lethality induced by I/R injury. 5 Our results point to an important role for NF-kappaB in triggering endogenous proinflammatory networks during intestinal I/R injury. Inhibition of NF-kappaB prevents tissue injury and lethality, and this was associated with inhibition of TNF-alpha production and decrease in neutrophil recruitment.
Animals↗
ICG-001, a novel small molecule regulator of TCF/beta-catenin transcription.
Inherited and somatic mutations in the APC gene, a human tumor-suppressor, occur in a large percentage of colon cancers, leading to elevated levels of nuclear beta-Catenin, and to activation of TCF/beta-Catenin-responsive genes including cyclin D1 and c-myc. To identify small molecule antagonists of this pathway, we screened transformed colorectal cells with a secondary structure-templated chemical library, in search of compounds that attenuated a TCF/beta-Catenin-responsive reporter gene. From this library we selected ICG-001 (IC50=3 microM) as a lead compound. Design and synthesis of the chemical library and some preliminary biological evaluation is described.
Bridged Bicyclo Compounds, Heterocyclic↗
A small molecule inhibitor of beta-catenin/CREB-binding protein transcription [corrected].
Inherited and somatic mutations in the adenomatous polyposis coli occur in most colon cancers, leading to activation of beta-catenin-responsive genes. To identify small molecule antagonists of this pathway, we challenged transformed colorectal cells with a secondary structure-templated chemical library, looking for compounds that inhibit a beta-catenin-responsive reporter. We identified ICG-001, a small molecule that down-regulates beta-catenin/T cell factor signaling by specifically binding to cyclic AMP response element-binding protein. ICG-001 selectively induces apoptosis in transformed cells but not in normal colon cells, reduces in vitro growth of colon carcinoma cells, and is efficacious in the Min mouse and nude mouse xenograft models of colon cancer.
Adenomatous Polyposis Coli↗
Design and synthesis of phosphotyrosine mimetics.
Selective inhibitors of protein tyrosine phosphatases (PTPases) are of great interest as therapeutic agents and research tools. Several phenylalanine derivatives (1, 2) designed as phosphotyrosine mimetics or irreversible active site inhibitors were successfully synthesized, then incorporated into a combinatorial library based on a peptidomimetic beta-strand template.
Biomimetic Materials↗
High-throughput synthesis and optimization of thrombin inhibitors via urazole alpha-addition and Michael addition.
A novel alpha-addition of propiolates to urazoles followed by Michael addition of a variety of nucleophiles has been developed for rapid production and optimization of peptidomimetic drug leads. This technology has produced a number of highly potent and selective inhibitors of the serine protease, thrombin.
Alkynes↗
Chemogenomic identification of Ref-1/AP-1 as a therapeutic target for asthma.
Asthma is characterized by an oxidantantioxidant imbalance in the lungs leading to activation of redox-sensitive transcription factors, nuclear factor kappaB (NF-kappaB), and activator protein-1 (AP-1). To develop therapeutic strategies for asthma, we used a chemogenomics approach to screen for small molecule inhibitor(s) of AP-1 transcription. We developed a beta-strand mimetic template that acts as a reversible inhibitor (pseudosubstrate) of redox proteins. This template incorporates an enedione moiety to trap reactive cysteine nucleophiles in the active sites of redox proteins. Specificity for individual redox factors was achieved through variations in X and Y functionality by using a combinatorial library approach. A limited array (2 x 6) was constructed where X was either NHCH(3) or NHCH(2) Ph and Y was methyl, phenyl, m-cyanophenyl, m-nitrophenyl, m-acetylaniline, or m-methylbenzoate. These analogs were evaluated for their ability to inhibit transcription in transiently transfected human lung epithelial A549 cells from either an AP-1 or NF-kappaB reporter. A small-molecule inhibitor, PNRI-299, was identified that selectively inhibited AP-1 transcription (IC(50) of 20 microM) without affecting NF-kappaB transcription (up to 200 microM) or thioredoxin (up to 200 microM). The molecular target of PNRI-299 was determined to be the oxidoreductase, redox effector factor-1 by an affinity chromatography approach. The selective redox effector factor-1 inhibitor, PNRI-299, significantly reduced airway eosinophil infiltration, mucus hypersecretion, edema, and IL-4 levels in a mouse asthma model. These data validate AP-1 as an important therapeutic target in allergic airway inflammation.
Animals↗
Chemogenomics with peptide secondary structure mimetics.
There is increasing evidence that redox regulation of transcription, particularly activator protein-1 (AP-1) and nuclear factor kappa B (NF-kappaB), is important in inflammatory diseases. Human thioredoxin (TRX), a member of the oxidoreductase superfamily, was initially identified, as a factor which augments the production of interleukin-2 receptor alpha (IL-2R alpha) in human T-cell lymphotropic virus type 1 (HTLV-1) infected patient T-cells. Substrates for the redox activity of TRX bind the active site cleft in extended strand structure. The rapid generation of high numbers of peptide secondary structure mimetics through solid-phase synthesis is a key technology for the identification of pharmaceutical leads based on such protein-peptide interactions. In this manuscript, we describe a chemogenomic approach utilizing an extended strand templated library to develop small molecule inhibitors to validate oxidoreductase molecular targets in a murine asthma model.
Animals↗
A small molecule inhibitor of redox-regulated NF-kappa B and activator protein-1 transcription blocks allergic airway inflammation in a mouse asthma model.
An oxidant/antioxidant imbalance is seen in the lungs of patients with asthma. This oxidative stress in asthmatic airways may lead to activation of redox-sensitive transcription factors, NF-kappaB and AP-1. We examined the effect of the small molecule inhibitor of redox-regulated NF-kappaB and AP-1 transcription, MOL 294 on airway inflammation and airway hyperreactivity (AHR) in a mouse model of asthma. MOL 294 is a potent nonpeptide inhibitor of NF-kappaB and AP-1 based upon a beta-strand template that binds to and inhibits the cellular redox protein thioredoxin. BALB/c mice after i.p. OVA sensitization (day 0) were challenged with intranasal OVA on days 14, 25, 26, and 27. MOL 294, administered intranasal on days 25-27, blocked the airway inflammatory response to OVA assessed 24 h after the last OVA challenge on day 28. MOL 294 reduced eosinophil, IL-13, and eotaxin levels in bronchoalveolar lavage fluid and airway tissue eosinophilia and mucus hypersecretion. MOL 294 also decreased AHR in vivo to methacholine. These results support redox-regulated transcription as a therapeutic target in asthma and demonstrate that selective inhibitors can reduce allergic airway inflammation and AHR.
Administration, Intranasal↗
Design, synthesis, and evaluation of opioid analogues with non-peptidic beta-turn scaffold: enkephalin and endomorphin mimetics.
We have identified a mu-selective opioid receptor agonist without a cationic amino group in the molecule from libraries of bicyclic beta-turn peptidomimetics. The biologically active conformation of the lead is proposed to mimic an endomorphin type III 4 --> 1 beta-turn conformation.
Enkephalins↗
Tryptase inhibition blocks airway inflammation in a mouse asthma model.
Release of human lung mast cell tryptase may be important in the pathophysiology of asthma. We examined the effect of the reversible, nonelectrophilic tryptase inhibitor MOL 6131 on airway inflammation and hyper-reactivity in a murine model of asthma. MOL 6131 is a potent selective nonpeptide inhibitor of human lung mast cell tryptase based upon a beta-strand template (K(i) = 45 nM) that does not inhibit trypsin (K(i) = 1,061 nM), thrombin (K(i) = 23, 640 nM), or other serine proteases. BALB/c mice after i.p. OVA sensitization (day 0) were challenged intratracheally with OVA on days 8, 15, 18, and 21. MOL 6131, administered days 18-21, blocked the airway inflammatory response to OVA assessed 24 h after the last OVA challenge on day 22; intranasal delivery (10 mg/kg) had a greater anti-inflammatory effect than oral delivery (10 or 25 mg/kg) of MOL 6131. MOL 6131 reduced total cells and eosinophils in bronchoalveolar lavage fluid, airway tissue eosinophilia, goblet cell hyperplasia, mucus secretion, and peribronchial edema and also inhibited the release of IL-4 and IL-13 in bronchoalveolar lavage fluid. However, tryptase inhibition did not alter airway hyper-reactivity to methacholine in vivo. These results support tryptase as a therapeutic target in asthma and indicate that selective tryptase inhibitors can reduce allergic airway inflammation.
Animals↗
Design, synthesis, and application of peptide secondary structure mimetics.
The secondary structure peptidomimetic approach is a rational way to develop novel nonpeptide pharmaceutical agents based upon biologically significant proteinaceous leads. A part of this approach elaborated in this laboratory over the past ten years is reviewed along with the recent developments in this field.
Crystallography, X-Ray↗
Temporal knowledge representation for scheduling tasks in clinical trial protocols.
Clinical trial protocols include detailed temporal constraints on treatment and associated tasks. Unlike health-care guidelines, protocols are highly prescriptive. Therefore, informatics applications that enforce such temporal constraints are more directly useful with protocols than with guidelines. Although there are some temporal knowledge representation efforts for health-care guidelines, we find these to be insufficiently expressive for clinical trial protocols. In this paper, we focus on temporal knowledge representation for clinical trial protocols and the task of patient-specific scheduling in protocols. We define a temporal ontology, use it to encode clinical trial protocols, and describe a prototype tool to carry out patient-specific scheduling for the tasks in protocols. We predict that an expressive temporal knowledge representation can support a number of scheduling and management tasks for protocol-based care.
Appointments and Schedules↗