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1.
Am J Physiol Renal Physiol ; 311(6): F1271-F1279, 2016 12 01.
Article in English | MEDLINE | ID: mdl-27582098

ABSTRACT

Proteinuria is a major risk factor for chronic kidney disease progression. Furthermore, exposure of proximal tubular epithelial cells to excess albumin promotes tubular atrophy and fibrosis, key predictors of progressive organ dysfunction. However, the link between proteinuria and tubular damage is unclear. We propose that pathological albumin exposure impairs proximal tubular autophagy, an essential process for recycling damaged organelles and toxic intracellular macromolecules. In both mouse primary proximal tubule and immortalized human kidney cells, albumin exposure decreased the number of autophagosomes, visualized by the autophagosome-specific fluorescent markers monodansylcadaverine and GFP-LC3, respectively. Similarly, renal cortical tissue harvested from proteinuric mice contained reduced numbers of autophagosomes on electron micrographs, and immunoblots showed reduced steady-state LC3-II content. Albumin exposure decreased autophagic flux in vitro in a concentration-dependent manner as assessed by LC3-II accumulation rate in the presence of bafilomycin, an H+-ATPase inhibitor that prevents lysosomal LC3-II degradation. In addition, albumin treatment significantly increased the half-life of radiolabeled long-lived proteins, indicating that the primary mechanism of degradation, autophagy, is dysfunctional. In vitro, mammalian target of rapamycin (mTOR) activation, a potent autophagy inhibitor, suppressed autophagy as a result of intracellular amino acid accumulation from lysosomal albumin degradation. mTOR activation was demonstrated by the increased phosphorylation of its downstream target, S6K, with free amino acid or albumin exposure. We propose that excess albumin uptake and degradation inhibit proximal tubule autophagy via an mTOR-mediated mechanism and contribute to progressive tubular injury.


Subject(s)
Autophagosomes/metabolism , Autophagy/physiology , Kidney Tubules, Proximal/metabolism , Proteinuria/metabolism , Animals , Cell Line , Humans , Mice , Phosphorylation , TOR Serine-Threonine Kinases/metabolism
2.
Gene ; 589(1): 1-11, 2016 Sep 01.
Article in English | MEDLINE | ID: mdl-27155521

ABSTRACT

The family of JADE proteins includes three paralogues encoded by individual genes and designated PHF17 (JADE1), PHF16 (JADE2), and PHF15 (JADE3). All three JADE proteins bear in tandem two Plant Homeo-domains (PHD) which are zinc finger domains. This review focuses on one member of the JADE family, JADE1. Studies addressing the biochemical, cellular and biological role of JADE1 are discussed. Recent discoveries of JADE1 function in the regulation of the epithelial cell cycle with potential relevance to disease are presented. Unresolved questions and future directions are formulated.


Subject(s)
Acute Kidney Injury/genetics , Epithelial Cells/metabolism , Gene Expression Regulation , Homeodomain Proteins/genetics , Neoplasms/genetics , Regeneration/genetics , Tumor Suppressor Proteins/genetics , Acute Kidney Injury/metabolism , Acute Kidney Injury/pathology , Amino Acid Sequence , Animals , Cell Cycle/genetics , Chromosomes, Human, Pair 4/chemistry , Epithelial Cells/cytology , Homeodomain Proteins/chemistry , Homeodomain Proteins/metabolism , Humans , Mice , Neoplasms/metabolism , Neoplasms/pathology , Protein Isoforms/chemistry , Protein Isoforms/genetics , Protein Isoforms/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Signal Transduction , Tumor Suppressor Proteins/chemistry , Tumor Suppressor Proteins/metabolism , Von Hippel-Lindau Tumor Suppressor Protein/genetics , Von Hippel-Lindau Tumor Suppressor Protein/metabolism
3.
Cell Cycle ; 14(17): 2821-34, 2015.
Article in English | MEDLINE | ID: mdl-26151225

ABSTRACT

JADE1 belongs to a small family of PHD zinc finger proteins that interacts with histone acetyl transferase (HAT) HBO1 and is associated with chromatin. We recently reported JADE1 chromatin shuttling and phosphorylation during G2/M to G1 transition, which was sensitive to Aurora A inhibition. In the current study we examined mechanisms of the cell cycle regulation by the small isoform of JADE1 protein, JADE1S, and report data showing that JADE1S has a novel function in the regulation of cytokinesis. Using FACS assays, we show that, JADE1S depletion facilitated rates of G1-cells accumulation in synchronously dividing HeLa cell cultures. Depletion of JADE1S protein in asynchronously dividing cells decreased the proportion of cytokinetic cells, and increased the proportion of multi-nuclear cells, indicative of premature and failed cytokinesis. In contrast, moderate overexpression of JADE1S increased the number of cytokinetic cells in time- and dose- dependent manner, indicating cytokinetic delay. Pharmacological inhibition of Aurora B kinase resulted in the release of JADE1S-mediated cytokinetic delay and allowed progression of abscission in cells over-expressing JADE1S. Finally, we show that JADE1S protein localized to centrosomes in interphase and mitotic cells, while during cytokinesis JADE1S localized to the midbody. Neither JADE1L nor partner of JADE1, HAT HBO1 was localized to the centrosomes or midbodies. Our study identifies the novel role for JADE1S in regulation of cytokinesis and suggests function in Aurora B kinase-mediated cytokinesis checkpoint.


Subject(s)
Cytokinesis/physiology , Epithelial Cells/physiology , Homeodomain Proteins/physiology , Tumor Suppressor Proteins/physiology , HEK293 Cells , HeLa Cells , Humans , MCF-7 Cells
4.
Cell Cycle ; 13(12): 1885-901, 2014.
Article in English | MEDLINE | ID: mdl-24739512

ABSTRACT

HAT HBO1 interacts with 2 isoforms of JADE1: JADE1S and JADE1L. JADE1 promotes acetylation of nucleosomal histones by HBO1. HBO1-JADE1 complex facilitates cell proliferation by unclear mechanisms. Here we report intracellular chromatin shuttling of HBO1-JADE1 complex during mitosis coupled to phosphorylation of JADE1. In interphase of dividing cells JADE1S was localized to the nucleus and associated with chromatin. As cells approached mitosis, specifically prophase, JADE1S dissociated from chromatin and associated with cytoplasm. JADE1S chromatin re-association began in telophase and paralleled nuclear envelope membrane reassembly. By early G1, JADE1S was re-associated with chromatin and localized to the nucleus. Importantly, cytoplasmic but not chromatin-associated JADE1 protein was phosphorylated. Mass-Spectrometric analysis of JADE1S protein isolated from G2/M-arrested cells identified 6 phosphorylated amino acid residues: S89, T92, S102, S121, S392, and T468, including 3 novel sites. Temporally, JADE1S phosphorylation and dephosphorylation during mitosis correlated with JADE1S chromatin dissociation and recruitment. JADE1S chromatin recruitment was accompanied by the global histone H4 acetylation. Pharmacological inhibitor of Aurora A kinase prevented JADE1S protein band shift and chromatin dissociation, suggesting regulatory function for phosphorylation. In vivo experiments supported our in vitro results. In mouse kidneys, JADE1S transiently accumulated in the cytoplasm of tubular epithelial cells during kidney regeneration. The transient increase in the number of cells with cytoplasmic JADE1S directly correlated with activation of tubular cell proliferation and inversely correlated with the number of cells with nuclear JADE1S staining, supporting biological role of HBO1-JADE1 shuttling during organ regeneration.


Subject(s)
Cell Cycle/physiology , Chromatin/metabolism , Histone Acetyltransferases/metabolism , Homeodomain Proteins/metabolism , Tumor Suppressor Proteins/metabolism , Acute Kidney Injury/metabolism , Acute Kidney Injury/pathology , Acute Kidney Injury/physiopathology , Animals , Cell Line, Tumor , Epithelial Cells/pathology , Epithelial Cells/physiology , Humans , Kidney Glomerulus/metabolism , Kidney Glomerulus/pathology , Kidney Glomerulus/physiopathology , Male , Mice, Inbred C57BL , Mitosis , Multiprotein Complexes/metabolism , Phosphorylation , Regeneration , Reperfusion Injury/metabolism , Reperfusion Injury/pathology , Reperfusion Injury/physiopathology
5.
Am J Pathol ; 182(1): 152-62, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23159946

ABSTRACT

HBO1 acetylates lysine residues of histones and is involved in DNA replication and gene transcription. Two isoforms of JADE1, JADE1S and JADE1L, bind HBO1 and promote acetylation of histones in chromatin context. We characterized the role of JADE1-HBO1 complexes in vitro and in vivo during epithelial cell replication. Down-regulation of JADE1 by siRNA diminished the rate of DNA synthesis in cultured cells, decreased endogenous HBO1 protein expression, and prevented chromatin recruitment of replication factor Mcm7, demonstrating that JADE1 is required for cell proliferation. We used a murine model of acute kidney injury to examine expression of HBO1-JADE1S/L in injured and regenerating epithelial tissue. In control kidneys, JADE1S, JADE1L, and HBO1 were expressed in nuclei of proximal and distal tubular epithelial cells. Ischemia and reperfusion injury resulted in an initial decrease in JADE1S, JADE1L, and HBO1 protein levels, which returned to baseline during renal recovery. HBO1 and JADE1S recovered as cell proliferation reached its maximum, whereas JADE1L recovered after bulk proliferation had ceased. The temporal expression of JADE1S correlated with the acetylation of histone H4 on lysines 5 and 12, but not with acetylation of histone H3 on lysine 14, demonstrating that the JADE1S-HBO1 complex specifically marks H4 during epithelial cell proliferation. These data implicate JADE1-HBO1 complex in acute kidney injury and suggest distinct roles for JADE1 isoforms during epithelial cell recovery.


Subject(s)
Epithelial Cells/physiology , Histone Acetyltransferases/metabolism , Homeodomain Proteins/biosynthesis , Tumor Suppressor Proteins/biosynthesis , Acute Kidney Injury/etiology , Acute Kidney Injury/genetics , Acute Kidney Injury/pathology , Acute Kidney Injury/physiopathology , Animals , Cell Line , Cell Nucleus/metabolism , Cell Proliferation , DNA Replication , Down-Regulation , Epithelial Cells/metabolism , Gene Silencing , Histone Acetyltransferases/biosynthesis , Histone Acetyltransferases/genetics , Homeodomain Proteins/genetics , Humans , Kidney Tubules/metabolism , Mice , Protein Isoforms/biosynthesis , Protein Isoforms/genetics , RNA, Small Interfering/genetics , Regeneration/genetics , Regeneration/physiology , Reperfusion Injury/complications , Reperfusion Injury/genetics , Reperfusion Injury/metabolism , Reperfusion Injury/pathology , Tumor Suppressor Proteins/genetics
6.
Hum Mol Genet ; 21(26): 5456-71, 2012 Dec 15.
Article in English | MEDLINE | ID: mdl-23001567

ABSTRACT

Autosomal-dominant polycystic kidney disease (ADPKD) and von Hippel-Lindau (VHL) disease lead to large kidney cysts that share pathogenetic features. The polycystin-1 (PC1) and pVHL proteins may therefore participate in the same key signaling pathways. Jade-1 is a pro-apoptotic and growth suppressive ubiquitin ligase for beta-catenin and transcriptional coactivator associated with histone acetyltransferase activity that is stabilized by pVHL in a manner that correlates with risk of VHL renal disease. Thus, a relationship between Jade-1 and PC1 was sought. Full-length PC1 bound, stabilized and colocalized with Jade-1 and inhibited Jade-1 ubiquitination. In contrast, the cytoplasmic tail or the naturally occurring C-terminal fragment of PC1 (PC1-CTF) promoted Jade-1 ubiquitination and degradation, suggesting a dominant-negative mechanism. ADPKD-associated PC1 mutants failed to regulate Jade-1, indicating a potential disease link. Jade-1 ubiquitination was mediated by Siah-1, an E3 ligase that binds PC1. By controlling Jade-1 abundance, PC1 and the PC1-CTF differentially regulate Jade-1-mediated transcriptional activity. A key target of PC1, the cyclin-dependent kinase inhibitor p21, is also up-regulated by Jade-1. Through Jade-1, PC1 and PC1 cleaved forms may exert fine control of beta-catenin and canonical Wnt signaling, a critical pathway in cystic renal disease. Thus, Jade-1 is a transcription factor and ubiquitin ligase whose activity is regulated by PC1 in a manner that is physiologic and may correlate with disease. Jade-1 may be an important therapeutic target in renal cystogenesis.


Subject(s)
Gene Expression Regulation , Homeodomain Proteins/metabolism , TRPP Cation Channels/metabolism , Tumor Suppressor Proteins/metabolism , Ubiquitination , Amino Acid Sequence , Apoptosis , Cyclin-Dependent Kinase Inhibitor p21/genetics , Cyclin-Dependent Kinase Inhibitor p21/metabolism , HEK293 Cells , Half-Life , Homeodomain Proteins/genetics , Humans , Kidney/cytology , Kidney/pathology , Molecular Sequence Data , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Polycystic Kidney, Autosomal Dominant/genetics , Polycystic Kidney, Autosomal Dominant/pathology , Proteasome Endopeptidase Complex/metabolism , TRPP Cation Channels/genetics , Transcription Factors/genetics , Transcription Factors/metabolism , Tumor Suppressor Proteins/genetics , Ubiquitin-Protein Ligases/genetics , Ubiquitin-Protein Ligases/metabolism , Up-Regulation , Von Hippel-Lindau Tumor Suppressor Protein/genetics , Von Hippel-Lindau Tumor Suppressor Protein/metabolism , Wnt Signaling Pathway , beta Catenin/genetics , beta Catenin/metabolism , von Hippel-Lindau Disease/genetics , von Hippel-Lindau Disease/metabolism
7.
Nat Cell Biol ; 10(10): 1208-16, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18806787

ABSTRACT

The von Hippel-Lindau protein pVHL suppresses renal tumorigenesis in part by promoting the degradation of hypoxia-inducible HIF-alpha transcription factors; additional mechanisms have been proposed. pVHL also stabilizes the plant homeodomain protein Jade-1, which is a candidate renal tumour suppressor that may correlate with renal cancer risk. Here we show that Jade-1 binds the oncoprotein beta-catenin in Wnt-responsive fashion. Moreover, Jade-1 destabilizes wild-type beta-catenin but not a cancer-causing form of beta-catenin. Whereas the well-established beta-catenin E3 ubiquitin ligase component beta-TrCP ubiquitylates only phosphorylated beta-catenin, Jade-1 ubiquitylates both phosphorylated and non-phosphorylated beta-catenin and therefore regulates canonical Wnt signalling in both Wnt-off and Wnt-on phases. Thus, the different characteristics of beta-TrCP and Jade-1 may ensure optimal Wnt pathway regulation. Furthermore, pVHL downregulates beta-catenin in a Jade-1-dependent manner and inhibits Wnt signalling, supporting a role for Jade-1 and Wnt signalling in renal tumorigenesis. The pVHL tumour suppressor and the Wnt tumorigenesis pathway are therefore directly linked through Jade-1.


Subject(s)
Homeodomain Proteins/metabolism , Signal Transduction , Tumor Suppressor Proteins/metabolism , Ubiquitination , Von Hippel-Lindau Tumor Suppressor Protein/metabolism , Wnt Proteins/metabolism , beta Catenin/metabolism , Animals , Cell Line , Humans , Protein Binding , Wnt Proteins/antagonists & inhibitors , Xenopus
8.
J Biol Chem ; 283(43): 28817-26, 2008 Oct 24.
Article in English | MEDLINE | ID: mdl-18684714

ABSTRACT

Regulation of global chromatin acetylation is important for chromatin remodeling. A small family of Jade proteins includes Jade-1L, Jade-2, and Jade-3, each bearing two mid-molecule tandem plant homology domain (PHD) zinc fingers. We previously demonstrated that the short isoform of Jade-1L protein, Jade-1, is associated with endogenous histone acetyltransferase (HAT) activity. It has been found that Jade-1L/2/3 proteins co-purify with a novel HAT complex, consisting of HBO1, ING4/5, and Eaf6. We investigated a role for Jade-1/1L in the HBO1 complex. When overexpressed individually, neither Jade-1/1L nor HBO1 affected histone acetylation. However, co-expression of Jade-1/1L and HBO1 increased acetylation of the bulk of endogenous histone H4 in epithelial cells in a synergistic manner, suggesting that Jade1/1L positively regulates HBO1 HAT activity. Conversely, small interfering RNA-mediated depletion of endogenous Jade resulted in reduced levels of H4 acetylation. Moreover, HBO1-mediated H4 acetylation activity was enhanced severalfold by the presence of Jade-1/1L in vitro. The removal of PHD fingers affected neither binding nor mutual Jade-1-HBO1 stabilization but completely abrogated the synergistic Jade-1/1L- and HBO1-mediated histone H4 acetylation in live cells and in vitro with reconstituted oligonucleosome substrates. Therefore, PHDs are necessary for Jade-1/1L-induced acetylation of nucleosomal histones by HBO1. In contrast to Jade-1/1L, the PHD zinc finger protein ING4/5 failed to synergize with HBO1 to promote histone acetylation. The physical interaction of ING4/5 with HBO1 occurred in the presence of Jade-1L or Jade-3 but not with the Jade-1 short isoform. In summary, this study demonstrates that Jade-1/1L are crucial co-factors for HBO1-mediated histone H4 acetylation.


Subject(s)
Histone Acetyltransferases/physiology , Homeodomain Proteins/physiology , Tumor Suppressor Proteins/physiology , Cell Line , Cell Nucleus/metabolism , Chromatin/metabolism , Gene Expression Regulation , Gene Expression Regulation, Enzymologic , Genes, Reporter , Histone Acetyltransferases/metabolism , Histones/metabolism , Homeodomain Proteins/metabolism , Humans , Models, Biological , Protein Isoforms , RNA, Small Interfering/metabolism , Transfection , Tumor Suppressor Proteins/metabolism
9.
Am J Physiol Lung Cell Mol Physiol ; 291(2): L232-43, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16473861

ABSTRACT

Neutrophil elastase (NE) plays an important role in emphysema, a pulmonary disease associated with excessive elastolysis and ineffective repair of interstitial elastin. Besides its direct elastolytic activity, NE releases soluble epidermal growth factor receptor (EGFR) ligands and initiates EGFR/MEK/ERK signaling to downregulate tropoelastin mRNA in neonatal rat lung fibroblasts (DiCamillo SJ, Carreras I, Panchenko MV, Stone PJ, Nugent MA, Foster JA, and Panchenko MP. J Biol Chem 277: 18938-18946, 2002). We now report that NE downregulates tropoelastin mRNA in the rat fetal lung fibroblast line RFL-6. The tropoelastin mRNA downregulation is preceded by release of EGF-like and TGF-alpha-like polypeptides and requires EGFR/MEK/ERK signaling, because it is prevented by the EGFR inhibitor AG1478 and the MEK/ERK uncoupler U0126. Tropoelastin expression in RFL-6 fibroblasts is governed by autocrine TGF-beta signaling, because TGF-beta type I receptor kinase inhibitor or TGF-beta neutralizing antibody dramatically decreases tropoelastin mRNA and protein levels. Half-life of tropoelastin mRNA in RFL-6 cells is >24 h, but it is decreased to approximately 8 h by addition of TGF-beta neutralizing antibody, EGF, TGF-alpha, or NE. Tropoelastin mRNA destabilization by NE, EGF, or TGF-alpha is abolished by AG1478 or U0126. EGF-dependent tropoelastin mRNA downregulation is reversed upon ligand withdrawal, whereas chronic EGF treatment leads to persistent downregulation of tropoelastin mRNA and protein levels and decreases insoluble elastin deposition. We conclude that NE-initiated EGFR/MEK/ERK signaling cascade overrides the autocrine TGF-beta signaling on tropoelastin mRNA stability and, therefore, decreases the elastogenic response in RFL-6 fibroblasts. We hypothesize that persistent EGFR/MEK/ERK signaling could impede the TGF-beta-induced elastogenesis/elastin repair in the chronically inflamed, elastase/anti-elastase imbalanced lung in emphysema.


Subject(s)
ErbB Receptors/metabolism , Extracellular Signal-Regulated MAP Kinases/metabolism , Fibroblasts/physiology , Leukocyte Elastase/metabolism , MAP Kinase Kinase 1/metabolism , Signal Transduction/physiology , Transforming Growth Factor beta/metabolism , Tropoelastin/metabolism , Animals , Autocrine Communication , Cell Line , Dichlororibofuranosylbenzimidazole/metabolism , Enzyme Inhibitors/metabolism , Fibroblasts/cytology , Fibroblasts/ultrastructure , Gene Expression Regulation , Humans , Lung/cytology , Mice , Nucleic Acid Synthesis Inhibitors/metabolism , RNA Stability , RNA, Messenger/metabolism , Rats , Tropoelastin/genetics
10.
Proc Natl Acad Sci U S A ; 102(31): 11035-40, 2005 Aug 02.
Article in English | MEDLINE | ID: mdl-16046545

ABSTRACT

Medical therapies are lacking for advanced renal cancer, so there is a great need to understand its pathogenesis. Most renal cancers have defects in the von Hippel-Lindau tumor suppressor pVHL. The mechanism by which pVHL protein functions in renal tumor suppression remains unclear. Jade-1 is a short-lived, kidney-enriched transcription factor that is stabilized by direct interaction with pVHL. Loss of Jade-1 stabilization by pVHL correlates with renal cancer risk, making the relationship between Jade-1 and renal cancer compelling. We report that Jade-1 expression was barely detectable in all tested renal cancer cell lines, regardless of VHL status. Strikingly, proteasome inhibitor treatment increased endogenous Jade-1 expression up to 10-fold. Jade-1 inhibited renal cancer cell growth, colony formation, and tumor formation in nude mice. Intriguingly, Jade-1 also affected the pattern of cell growth in monolayer culture and 3D culture. Jade-1 increased apoptosis by 40-50% and decreased levels of antiapoptotic Bcl-2. Antisense Jade-1-expressing cells confirmed these results. Therefore, Jade-1 may suppress renal cancer cell growth in part by increasing apoptosis. Jade-1 may represent a proapoptotic barrier to proliferation that must be overcome generally in renal cancer, perhaps initially by pVHL inactivation and subsequently by increased proteasomal activity. Therefore, Jade-1 may be a renal tumor suppressor.


Subject(s)
Homeodomain Proteins/genetics , Kidney Neoplasms/genetics , Kidney Neoplasms/pathology , Tumor Suppressor Proteins/genetics , Animals , Apoptosis , Cell Line, Tumor , DNA, Antisense/genetics , Gene Expression/drug effects , Genes, Tumor Suppressor , Homeodomain Proteins/physiology , Humans , Male , Mice , Mice, Nude , Protease Inhibitors/pharmacology , Tumor Suppressor Proteins/physiology , Ubiquitin-Protein Ligases/genetics , Von Hippel-Lindau Tumor Suppressor Protein
11.
J Biol Chem ; 279(53): 56032-41, 2004 Dec 31.
Article in English | MEDLINE | ID: mdl-15502158

ABSTRACT

Jade-1 was identified as a protein partner of the von Hippel-Lindau tumor suppressor pVHL. The interaction of Jade-1 and pVHL correlates with renal cancer risk. We have investigated the molecular function of Jade-1. Jade-1 has two zinc finger motifs called plant homeodomains (PHD). A line of evidence suggests that the PHD finger functions in chromatin remodeling and protein-protein interactions. We determined the cellular localization of Jade-1 and examined whether Jade-1 might have transcriptional and histone acetyltransferase (HAT) functions. Biochemical cell fractionation studies as well as confocal images of cells immunostained with a specific Jade-1 antibody revealed that endogenous Jade-1 is localized predominantly in the cell nucleus. Tethering of Gal4-Jade-1 fusion protein to Gal4-responsive promoters in co-transfection experiments activated transcription 5-6-fold, indicating that Jade-1 is a possible transcriptional activator. It was remarkable that overexpression of Jade-1 in cultured cells specifically increased levels of endogenous acetylated histone H4, but not histone H3, strongly suggesting that Jade-1 associates with HAT activity specific for histone H4. Deletion of the two PHD fingers completely abolished Jade-1 transcriptional and HAT activities, indicating that these domains are indispensable for Jade-1 nuclear functions. In addition, we demonstrated that TIP60, a known HAT with histone H4/H2A specificity, physically associates with Jade-1 and is able to augment Jade-1 HAT function in live cells, strongly suggesting that TIP60 might mediate Jade-1 HAT activity. Thus, Jade-1 is a novel candidate transcriptional co-activator associated with HAT activity and may play a key role in the pathogenesis of renal cancer and von Hippel-Lindau disease.


Subject(s)
Acetyltransferases/metabolism , Homeodomain Proteins/metabolism , Tumor Suppressor Proteins/metabolism , Ubiquitin-Protein Ligases/metabolism , Cell Line , Cell Nucleus/metabolism , Chloramphenicol O-Acetyltransferase/metabolism , Dose-Response Relationship, Drug , Electrophoresis, Polyacrylamide Gel , Genes, Reporter , Genetic Vectors , HeLa Cells , Histone Acetyltransferases , Histones/chemistry , Histones/metabolism , Humans , Immunoprecipitation , Lysine Acetyltransferase 5 , Microscopy, Confocal , Models, Biological , Models, Genetic , Promoter Regions, Genetic , Protein Binding , Protein Structure, Tertiary , Sodium Chloride/pharmacology , Subcellular Fractions , Transcription, Genetic , Transcriptional Activation , Transfection , Von Hippel-Lindau Tumor Suppressor Protein , Zinc Fingers
12.
J Biol Chem ; 277(21): 18938-46, 2002 May 24.
Article in English | MEDLINE | ID: mdl-11889128

ABSTRACT

Elastase/anti-elastase imbalance is a hallmark of emphysema, a chronic obstructive pulmonary disease associated with the rupture and inefficient repair of interstitial elastin. We report that neutrophil elastase (NE) at low physiologic concentrations, ranging from 35 nm to 1 microm, invokes transient, peaking at 15 min, activation of extracellular signal-regulated kinases 1 and 2 (ERK) in elastogenic lung fibroblasts. ERK activation is preceded by the release of soluble 25-26-kDa forms of epidermal growth factor (EGF) and transactivation of EGF receptor (EGFR) in NE-exposed cells. The stimulatory effect of NE on ERK is abrogated in the presence of anti-EGF-neutralizing antibodies, EGFR tyrosine kinase inhibitor (AG1478), and ERK kinase inhibitor (PD98059), as well as abolished in both EGFR-desensitized and endocytosis-arrested fibroblasts. Nuclear accumulation of activated ERK is associated with transient, peaking at 30 min, induction of c-Fos and sustained, observed at 24-48 h, decrease of tropoelastin mRNA levels in NE-challenged cells. Pretreatment of fibroblasts with AG1478 or PD98059 abrogates the NE-initiated tropoelastin mRNA suppression. We conclude that proteolytically released EGF signals directly via EGFR and ERK to down-regulate tropoelastin mRNA in NE-challenged lung fibroblasts.


Subject(s)
Down-Regulation , Epidermal Growth Factor/metabolism , ErbB Receptors/metabolism , Leukocyte Elastase/metabolism , Lung/metabolism , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinases/metabolism , Tropoelastin/genetics , Animals , Epidermal Growth Factor/antagonists & inhibitors , Fibroblasts/metabolism , Humans , Lung/cytology , Mitogen-Activated Protein Kinase 3 , Quinazolines , RNA, Messenger/genetics , Rats , Rats, Sprague-Dawley , Signal Transduction , Tyrphostins/pharmacology
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