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1.
PM R ; 9(8): 795-803, 2017 Aug.
Article in English | MEDLINE | ID: mdl-27915067

ABSTRACT

BACKGROUND: Studies investigating the use and effectiveness of acupuncture in adults after exercise have been well documented. Fewer studies involving acupuncture have been completed in the adolescent athlete population. To our knowledge, there are no published studies that investigate the use of acupuncture in adolescent athletes within their field of play. OBJECTIVE: To primarily assess the feasibility of performing acupuncture in adolescent Nordic skiers within their athletic environment, and secondarily to measure the effect of acupuncture on muscle soreness and sense of well-being. DESIGN: Prospective feasibility study. SETTING: Local outdoor cross country ski trails and indoor lodge. PARTICIPANTS: Fifteen healthy participants (80% female, 20% male; age 14-17 years) were involved on at least 1 of 5 treatment days. INTERVENTION: Fifteen-minute treatments were administered using traditional needle acupuncture following the first 5 consecutive Nordic Ski Team practices of the season in an attempt to capture the effect of acupuncture on delayed-onset muscle soreness (DOMS). Acupuncture points specific to muscle groups in the lower limbs that are commonly reported as painful during Nordic skiing were chosen. Pre- and posttreatment surveys included visual analogue scales (VAS) to track participant responses. OUTCOME MEASURES: Time, cost, side effects, and participant to provider ratio was observed to determine feasibility. Effect on muscle soreness and sense of well-being was measured via pre- and posttreatment VAS (0-10) rating analyses. RESULTS: Total time required by research staff on treatment days was 90 minutes; total cost, $1500; temperature range, -13.9°C to -2.8°C, and largest participant to acupuncturist ratio, 7:1. No major side effects occurred. The majority (73%) of participants reported minimal side effects; most common was treatment site pain. The overall pre- to posttreatment effect on muscle soreness (average over 5 days) demonstrated significantly improved posttreatment scores (P = .04). The effect of the day (average over pre- and posttreatment values) demonstrated significantly higher muscle soreness scores on day 3 versus day 1 (P = .03). At study completion, all participants indicated that they would consider acupuncture in the future and would recommend treatments to friends or teammates. CONCLUSION: Providing acupuncture to adolescent Nordic ski athletes in the practice field under extreme temperatures is feasible with the appropriate resources. Despite mild side effects, acupuncture was well received by the athletes. Lessons learned from this trial can provide a framework for delivering acupuncture to other athletes in their training environment. LEVEL OF EVIDENCE: IV.


Subject(s)
Acupuncture Therapy/methods , Myalgia/rehabilitation , Skiing/physiology , Adolescent , Feasibility Studies , Female , Humans , Male , Pain Management , Pain Measurement , Prospective Studies , Risk Assessment , Scandinavian and Nordic Countries
3.
J Sports Sci Med ; 14(2): 276-83, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25983575

ABSTRACT

Minimalist running footwear has grown increasingly popular. Prior studies that have compared lower extremity biomechanics in minimalist running to traditional running conditions are largely limited to a single running velocity. This study compares the effects of running at various speeds on foot strike pattern, stride length, knee angles and ankle angles in traditional, barefoot, and minimalist running conditions. Twenty-six recreational runners (19-46 years of age) ran on a treadmill at a range of speeds (2.5-4.0 m·sec(-1)). Subjects ran with four different footwear conditions: personal, standard, and minimalist shoes and barefoot. 3D coordinates from video data were collected. The relationships between speed, knee and ankle angles at foot strike and toe-off, relative step length, and footwear conditions were evaluated by ANCOVA, with speed as the co-variate. Distribution of non-rearfoot strike was compared across shod conditions with paired t-tests. Non-rearfoot strike distribution was not significantly affected by speed, but was different between shod conditions (p < 0.05). Footwear condition and speed significantly affected ankle angle at touchdown, independent of one another (F [3,71] = 10.28, p < 0.001), with barefoot and minimalist running exhibiting greater plantarflexion at foot strike. When controlling for foot strike style, barefoot and minimalist runners exhibited greater plantarflexion than other conditions (p < 0.05). Ankle angle at lift-off and relative step length exhibited a significant interaction between speed and shod condition. Knee angles had a significant relationship with speed, but not with footwear. There is a clear influence of footwear, but not speed, on foot strike pattern. Additionally, speed and footwear predict ankle angles (greater plantarflexion at foot strike) and may have implications for minimalist runners and their risk of injury. Long-term studies utilizing various speeds and habituation times are needed. Key pointsFoot strike style does not change with speed, but does change with shod condition, with minimalist shoes exhibiting an intermediate distribution of forefoot strikes between barefoot and traditional shoes.Plantarflexion at touchdown does change with speed and with shoe type, with barefoot and minimalist shoes exhibiting a greater plantarflexion angle than traditional running shoes.Knee angles change with speed in all shod conditions, but knee flexion at touchdown is not different between shod conditions.Relative step length changes with speed and shod condition, but there is an interaction between these variables such that step length increases more quickly in traditional shoes as speed increases.

4.
Cancer Res ; 74(5): 1390-1403, 2014 Mar 01.
Article in English | MEDLINE | ID: mdl-24590809

ABSTRACT

Proteins that communicate signals from the cytoskeleton to the nucleus are prime targets for effectors of metastasis as they often transduce signals regulating adhesion, motility, and invasiveness. LIM domain proteins shuttle between the cytoplasm and the nucleus, and bind to partners in both compartments, often coupling changes in gene expression to extracellular cues. In this work, we characterize LIMD2, a mechanistically undefined LIM-only protein originally found to be overexpressed in metastatic lesions but absent in the matched primary tumor. LIMD2 levels in fresh and archival tumors positively correlate with cell motility, metastatic potential, and grade, including bladder, melanoma, breast, and thyroid tumors. LIMD2 directly contributes to these cellular phenotypes as shown by overexpression, knockdown, and reconstitution experiments in cell culture models. The solution structure of LIMD2 that was determined using nuclear magnetic resonance revealed a classic LIM-domain structure that was highly related to LIM1 of PINCH1, a core component of the integrin-linked kinase-parvin-pinch complex. Structural and biochemical analyses revealed that LIMD2 bound directly to the kinase domain of integrin-linked kinase (ILK) near the active site and strongly activated ILK kinase activity. Cells that were null for ILK failed to respond to the induction of invasion by LIMD2. This strongly suggests that LIMD2 potentiates its biologic effects through direct interactions with ILK, a signal transduction pathway firmly linked to cell motility and invasion. In summary, LIMD2 is a new component of the signal transduction cascade that links integrin-mediated signaling to cell motility/metastatic behavior and may be a promising target for controlling tumor spread.


Subject(s)
Cell Movement/genetics , LIM Domain Proteins/genetics , LIM Domain Proteins/metabolism , Neoplasms/genetics , Neoplasms/metabolism , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Animals , Disease Progression , Fibroblasts/pathology , HEK293 Cells , Humans , MCF-7 Cells , Mice , Neoplasm Metastasis/genetics , Neoplasm Metastasis/pathology , Neoplasms/pathology , Protein Binding/genetics , Signal Transduction/genetics
5.
Oncotarget ; 4(7): 1075-92, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23919967

ABSTRACT

Castrate-Resistant Prostate Cancer (CRPC) is characterized by persistent androgen receptor-driven tumor growth in the apparent absence of systemic androgens. Current evidence suggests that CRPC cells can produce their own androgens from endogenous sterol precursors that act in an intracrine manner to stimulate tumor growth. The mechanisms by which CRPC cells become steroidogenic during tumor progression are not well defined. Herein we describe a novel link between the elevated cholesterol phenotype of CRPC and the TERE1 tumor suppressor protein, a prenyltransferase that synthesizes vitamin K-2, which is a potent endogenous ligand for the SXR nuclear hormone receptor. We show that 50% of primary and metastatic prostate cancer specimens exhibit a loss of TERE1 expression and we establish a correlation between TERE1 expression and cholesterol in the LnCaP-C81 steroidogenic cell model of the CRPC. LnCaP-C81 cells also lack TERE1 protein, and show elevated cholesterol synthetic rates, higher steady state levels of cholesterol, and increased expression of enzymes in the de novo cholesterol biosynthetic pathways than the non-steroidogenic prostate cancer cells. C81 cells also show decreased expression of the SXR nuclear hormone receptor and a panel of directly regulated SXR target genes that govern cholesterol efflux and steroid catabolism. Thus, a combination of increased synthesis, along with decreased efflux and catabolism likely underlies the CRPC phenotype: SXR might coordinately regulate this phenotype. Moreover, TERE1 controls synthesis of vitamin K-2, which is a potent endogenous ligand for SXR activation, strongly suggesting a link between TERE1 levels, K-2 synthesis and SXR target gene regulation. We demonstrate that following ectopic TERE1 expression or induction of endogenous TERE1, the elevated cholesterol levels in C81 cells are reduced. Moreover, reconstitution of TERE1 expression in C81 cells reactivates SXR and switches on a suite of SXR target genes that coordinately promote both cholesterol efflux and androgen catabolism. Thus, loss of TERE1 during tumor progression reduces K-2 levels resulting in reduced transcription of SXR target genes. We propose that TERE1 controls the CPRC phenotype by regulating the endogenous levels of Vitamin K-2 and hence the transcriptional control of a suite of steroidogenic genes via the SXR receptor. These data implicate the TERE1 protein as a previously unrecognized link affecting cholesterol and androgen accumulation that could govern acquisition of the CRPC phenotype.


Subject(s)
Cholesterol/metabolism , Dimethylallyltranstransferase/metabolism , Prostatic Neoplasms, Castration-Resistant/genetics , Prostatic Neoplasms, Castration-Resistant/metabolism , Receptors, Steroid/genetics , Cell Line, Tumor , Cholesterol/biosynthesis , Dimethylallyltranstransferase/biosynthesis , Dimethylallyltranstransferase/genetics , Gene Expression Regulation, Neoplastic , Humans , Ligands , Male , Phenotype , Pregnane X Receptor , Prostatic Neoplasms, Castration-Resistant/pathology , Receptors, Steroid/metabolism , Transfection , Vitamin K/pharmacology
6.
Int J Oncol ; 43(2): 638-52, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23759948

ABSTRACT

Current studies of the TERE1 (UBIAD1) protein emphasize its multifactorial influence on the cell, in part due to its broad sub-cellular distribution to mitochondria, endoplasmic reticulum and golgi. However, the profound effects of TERE1 relate to its prenyltransferase activity for synthesis of the bioactive quinones menaquinone and COQ10. Menaquinone (aka, vitamin K-2) serves multiple roles: as a carrier in mitochondrial electron transport, as a ligand for SXR nuclear hormone receptor activation, as a redox modulator, and as an alkylator of cellular targets. We initially described the TERE1 (UBIAD1) protein as a tumor suppressor based upon reduced expression in urological cancer specimens and the inhibition of growth of tumor cell lines/xenografts upon ectopic expression. To extend this potential tumor suppressor role for the TERE1 protein to renal cell carcinoma (RCC), we applied TERE1 immunohistochemistry to a TMA panel of 28 RCC lesions and determined that in 57% of RCC lesions, TERE1 expression was reduced (36%) or absent (21%). Ectopic TERE1 expression caused an 80% decrease in growth of Caki-1 and Caki-2 cell lines, a significantly decreased colony formation, and increased caspase 3/7 activity in a panel of RCC cell lines. Furthermore, TERE1 expression increased mitochondrial oxygen consumption and hydrogen production, oxidative stress and NO production. Based on the elevated cholesterol and altered metabolic phenotype of RCC, we also examined the effects of TERE1 and the interacting protein TBL2 on cellular cholesterol. Ectopic TERE1 or TBL2 expression in Caki-1, Caki-2 and HEK 293 cells reduced cholesterol by up to 40%. RT-PCR analysis determined that TERE1 activated several SXR targets known to regulate lipid metabolism, consistent with predictions based on its role in menaquinone synthesis. Loss of TERE1 may contribute to the altered lipid metabolic phenotype associated with progression in RCC via an uncoupling of ROS/RNS and SXR signaling from apoptosis by elevation of cholesterol.


Subject(s)
Carcinoma, Renal Cell/pathology , Cholesterol/metabolism , Dimethylallyltranstransferase/metabolism , Kidney Neoplasms/pathology , Apoptosis , Carcinoma, Renal Cell/metabolism , Caspase 3/metabolism , Caspase 7/metabolism , Cell Line, Tumor , Cell Proliferation , Dimethylallyltranstransferase/biosynthesis , Gene Expression Regulation, Neoplastic , HEK293 Cells , Humans , Hydrogen/metabolism , Kidney Neoplasms/metabolism , Lipid Metabolism , Mitochondria/metabolism , Nitric Oxide/metabolism , Oxidative Stress , Oxygen/metabolism , Pregnane X Receptor , Reactive Oxygen Species/metabolism , Receptors, Steroid/genetics , Ubiquinone/analogs & derivatives , Ubiquinone/biosynthesis , Vitamin K 2/metabolism
7.
J Cell Biochem ; 114(9): 2170-87, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23564352

ABSTRACT

We originally discovered TERE1 as a potential tumor suppressor protein based upon reduced expression in bladder and prostate cancer specimens and growth inhibition of tumor cell lines/xenografts upon ectopic expression. Analysis of TERE1 (aka UBIAD1) has shown it is a prenyltransferase enzyme in the natural bio-synthetic pathways for both vitamin K-2 and COQ10 production and exhibits multiple subcellular localizations including mitochondria, endoplasmic reticulum, and golgi. Vitamin K-2 is involved in mitochondrial electron transport, SXR nuclear hormone receptor signaling and redox cycling: together these functions may form the basis for tumor suppressor function. To gain further insight into mechanisms of growth suppression and enzymatic regulation of TERE1 we isolated TERE1 associated proteins and identified the WD40 repeat, mitochondrial protein TBL2. We examined whether disease specific mutations in TERE1 affected interactions with TBL2 and the role of each protein in altering mitochondrial function, ROS/RNS production and SXR target gene regulation. Biochemical binding assays demonstrated a direct, high affinity interaction between TERE1 and TBL2 proteins; TERE1 was localized to both mitochondrial and non-mitochondrial membranes whereas TBL2 was predominantly mitochondrial; multiple independent single amino acid substitutions in TERE1 which cause a human hereditary corneal disease reduced binding to TBL2 strongly suggesting the relevance of this interaction. Ectopic TERE1 expression elevated mitochondrial trans-membrane potential, oxidative stress, NO production, and activated SXR targets. A TERE1-TBL2 complex likely functions in oxidative/nitrosative stress, lipid metabolism, and SXR signaling pathways in its role as a tumor suppressor.


Subject(s)
Dimethylallyltranstransferase/metabolism , GTP-Binding Proteins/metabolism , Mitochondria/metabolism , Oxidative Stress/physiology , Reactive Nitrogen Species/metabolism , Cell Line , Dimethylallyltranstransferase/genetics , Fluorescent Antibody Technique, Indirect , GTP-Binding Proteins/genetics , Humans , Immunoprecipitation , Lipid Metabolism/genetics , Lipid Metabolism/physiology , Membrane Potentials/genetics , Membrane Potentials/physiology , Microscopy, Immunoelectron , Oxidative Stress/genetics , Protein Binding , Reactive Oxygen Species/metabolism , Reverse Transcriptase Polymerase Chain Reaction
8.
DNA Cell Biol ; 30(11): 851-64, 2011 Nov.
Article in English | MEDLINE | ID: mdl-21740188

ABSTRACT

Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression.


Subject(s)
Cholesterol/metabolism , Intracellular Space/metabolism , Proteins/genetics , Proteins/metabolism , Urinary Bladder Neoplasms/metabolism , Urinary Bladder Neoplasms/pathology , Amino Acid Sequence , Animals , Apolipoproteins E/metabolism , Cell Line, Tumor , Corneal Dystrophies, Hereditary/genetics , Dimethylallyltranstransferase , Disease Progression , GTP-Binding Proteins/genetics , GTP-Binding Proteins/metabolism , Gene Expression Regulation, Neoplastic , HEK293 Cells , Humans , Mice , Mice, Nude , Models, Molecular , Molecular Sequence Data , Mutation , Neoplasm Invasiveness , Oligonucleotide Array Sequence Analysis , Phenotype , Protein Structure, Tertiary , Proteins/chemistry , Urinary Bladder Neoplasms/genetics
9.
PLoS One ; 5(5): e10760, 2010 May 21.
Article in English | MEDLINE | ID: mdl-20505825

ABSTRACT

BACKGROUND: Mutations in a novel gene, UBIAD1, were recently found to cause the autosomal dominant eye disease Schnyder corneal dystrophy (SCD). SCD is characterized by an abnormal deposition of cholesterol and phospholipids in the cornea resulting in progressive corneal opacification and visual loss. We characterized lesions in the UBIAD1 gene in new SCD families and examined protein homology, localization, and structure. METHODOLOGY/PRINCIPAL FINDINGS: We characterized five novel mutations in the UBIAD1 gene in ten SCD families, including a first SCD family of Native American ethnicity. Examination of protein homology revealed that SCD altered amino acids which were highly conserved across species. Cell lines were established from patients including keratocytes obtained after corneal transplant surgery and lymphoblastoid cell lines from Epstein-Barr virus immortalized peripheral blood mononuclear cells. These were used to determine the subcellular localization of mutant and wild type protein, and to examine cholesterol metabolite ratios. Immunohistochemistry using antibodies specific for UBIAD1 protein in keratocytes revealed that both wild type and N102S protein were localized sub-cellularly to mitochondria. Analysis of cholesterol metabolites in patient cell line extracts showed no significant alteration in the presence of mutant protein indicating a potentially novel function of the UBIAD1 protein in cholesterol biochemistry. Molecular modeling was used to develop a model of human UBIAD1 protein in a membrane and revealed potentially critical roles for amino acids mutated in SCD. Potential primary and secondary substrate binding sites were identified and docking simulations indicated likely substrates including prenyl and phenolic molecules. CONCLUSIONS/SIGNIFICANCE: Accumulating evidence from the SCD familial mutation spectrum, protein homology across species, and molecular modeling suggest that protein function is likely down-regulated by SCD mutations. Mitochondrial UBIAD1 protein appears to have a highly conserved function that, at least in humans, is involved in cholesterol metabolism in a novel manner.


Subject(s)
Corneal Dystrophies, Hereditary/enzymology , Corneal Dystrophies, Hereditary/genetics , Dimethylallyltranstransferase/genetics , Mitochondria/enzymology , Mitochondria/genetics , Mutation/genetics , Proteins/genetics , Amino Acid Sequence , Amino Acids , Base Sequence , Cholesterol/metabolism , Conserved Sequence , Cornea/enzymology , Cornea/pathology , Corneal Dystrophies, Hereditary/pathology , DNA Mutational Analysis , Demography , Family , Humans , Linear Models , Models, Molecular , Molecular Sequence Data , Mutant Proteins/chemistry , Mutant Proteins/metabolism , Protein Transport , Proteins/chemistry
10.
Mol Cell ; 28(5): 823-37, 2007 Dec 14.
Article in English | MEDLINE | ID: mdl-18082607

ABSTRACT

Tandem PHD and bromodomains are often found in chromatin-associated proteins and have been shown to cooperate in gene silencing. Each domain can bind specifically modified histones: the mechanisms of cooperation between these domains are unknown. We show that the PHD domain of the KAP1 corepressor functions as an intramolecular E3 ligase for sumoylation of the adjacent bromodomain. The RING finger-like structure of the PHD domain is required for both Ubc9 binding and sumoylation and directs modification to specific lysine residues in the bromodomain. Sumoylation is required for KAP1-mediated gene silencing and functions by directly recruiting the SETDB1 histone methyltransferase and the CHD3/Mi2 component of the NuRD complex via SUMO-interacting motifs. Sumoylated KAP1 stimulates the histone methyltransferase activity of SETDB1. These data provide a mechanistic explanation for the cooperation of PHD and bromodomains in gene regulation and describe a function of the PHD domain as an intramolecular E3 SUMO ligase.


Subject(s)
DNA-Binding Proteins/genetics , Gene Expression Regulation , Gene Silencing , RING Finger Domains , Repressor Proteins/genetics , Small Ubiquitin-Related Modifier Proteins/metabolism , Ubiquitin-Protein Ligases/metabolism , Adenosine Triphosphatases/genetics , Adenosine Triphosphatases/metabolism , Autoantigens/genetics , Autoantigens/metabolism , Bone Neoplasms/genetics , Bone Neoplasms/metabolism , Bone Neoplasms/pathology , Cells, Cultured , Chromatin/metabolism , DNA Helicases/genetics , DNA Helicases/metabolism , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/metabolism , Histone Deacetylases/genetics , Histone Deacetylases/metabolism , Histone-Lysine N-Methyltransferase , Humans , Kidney/metabolism , Lysine/chemistry , Mi-2 Nucleosome Remodeling and Deacetylase Complex , Osteosarcoma/genetics , Osteosarcoma/metabolism , Osteosarcoma/pathology , Protein Methyltransferases/genetics , Protein Methyltransferases/metabolism , Protein Processing, Post-Translational , Repressor Proteins/antagonists & inhibitors , Repressor Proteins/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/metabolism , Transcription, Genetic , Tripartite Motif-Containing Protein 28 , Two-Hybrid System Techniques , Ubiquitin-Conjugating Enzymes/genetics , Ubiquitin-Conjugating Enzymes/metabolism , Ubiquitin-Protein Ligases/genetics
11.
Cancer Res ; 67(19): 9097-106, 2007 Oct 01.
Article in English | MEDLINE | ID: mdl-17909014

ABSTRACT

The SNAG repression domain is comprised of a highly conserved 21-amino acid sequence, is named for its presence in the Snail/growth factor independence-1 class of zinc finger transcription factors, and is present in a variety of proto-oncogenic transcription factors and developmental regulators. The prototype SNAG domain containing oncogene, growth factor independence-1, is responsible for the development of T cell thymomas. The SNAIL proteins also encode the SNAG domain and play key roles in epithelial mesenchymal differentiation events during development and metastasis. Significantly, these oncogenic functions require a functional SNAG domain. The molecular mechanisms of SNAG domain-mediated transcriptional repression are largely unknown. Using a yeast two-hybrid strategy, we identified Ajuba, a multiple LIM domain protein that can function as a corepressor for the SNAG domain. Ajuba interacts with the SNAG domain in vitro and in vivo, colocalizes with it, and enhances SNAG-mediated transcriptional repression. Ajuba shuttles between the cytoplasm and the nucleus and may form a novel intracellular signaling system. Using an integrated reporter gene combined with chromatin immunoprecipitation, we observed rapid, SNAG-dependent assembly of a multiprotein complex that included Ajuba, SNAG, and histone modifications consistent with the repressed state. Thus, SNAG domain proteins may bind Ajuba, trapping it in the nucleus where it functions as an adapter or molecular scaffold for the assembly of macromolecular repression complexes at target promoters.


Subject(s)
Homeodomain Proteins/metabolism , Transcription Factors/metabolism , Amino Acid Sequence , Animals , Binding Sites , Cell Nucleus/metabolism , Cytoplasm/metabolism , Homeodomain Proteins/genetics , LIM Domain Proteins , Mice , Molecular Sequence Data , NIH 3T3 Cells , PAX3 Transcription Factor , Paired Box Transcription Factors/genetics , Paired Box Transcription Factors/metabolism , Protein Structure, Tertiary , Repressor Proteins/genetics , Repressor Proteins/metabolism , Snail Family Transcription Factors , Transcription Factors/genetics , Transcription, Genetic
12.
EMBO J ; 24(18): 3279-90, 2005 Sep 21.
Article in English | MEDLINE | ID: mdl-16107876

ABSTRACT

MDM2 is a RING domain ubiquitin E3 ligase and a major regulator of the p53 tumor suppressor. MDM2 binds to p53, inactivates p53 transcription function, inhibits p53 acetylation, and promotes p53 degradation. Here, we present evidence that MDM2 interacts with the nuclear corepressor KAP1. The binding is mediated by the N-terminal coiled-coil domain of KAP1 and the central acidic domain of MDM2. KAP1 stimulates formation of p53-HDAC1 complex and inhibits p53 acetylation by interacting with MDM2. Expression of KAP1 cooperates with MDM2 to promote p53 ubiquitination and degradation. The tumor suppressor ARF competes with KAP1 in MDM2 binding; oncogene induction of ARF expression reduces MDM2-KAP1 interaction. Depletion of endogenous KAP1 expression by RNAi stimulates p53 transcriptional activity, sensitizes p53 response to DNA damage, and increases apoptosis. Therefore, MDM2 interaction with KAP1 contributes to p53 functional regulation. ARF may regulate p53 acetylation and stability in part by inhibiting KAP1-MDM2 binding.


Subject(s)
Cell Nucleus/metabolism , DNA-Binding Proteins/metabolism , Nuclear Proteins/metabolism , Proto-Oncogene Proteins/metabolism , Repressor Proteins/metabolism , Tumor Suppressor Protein p53/antagonists & inhibitors , Tumor Suppressor Protein p53/metabolism , Acetylation , Cell Line , DNA/genetics , DNA Damage , DNA-Binding Proteins/genetics , Histone Deacetylase 1 , Histone Deacetylases/metabolism , Humans , Mutation/genetics , Nuclear Proteins/genetics , Protein Binding , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-mdm2 , Repressor Proteins/genetics , Tripartite Motif-Containing Protein 28 , Ubiquitin/metabolism
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