Tung Liang Lee

Sumoylation of p45/NF-E2: Nuclear Positioning and Transcriptional Activation of the Mammalian β-Like Globin Gene Locus

ABSTRACT NF-E2 is a transcription activator for the regulation of a number of erythroid- and megakaryocytic lineage-specific genes. Here we present evidence that the large subunit of mammalian NF-E2, p45, is sumoylated in vivo in human erythroid K562 cells and in mouse fetal liver. By in vitro sumoylation reaction and DNA transfection experiments, we show that the sumoylation occurs at lysine 368 (K368) of human p45/NF-E2. Furthermore, p45 sumoylation enhances the transactivation capability of NF-E2, and this is accompanied by an increase of the NF-E2 DNA binding affinity. More interestingly, we have found that in K562 cells, the β-globin gene loci in the euchromatin regions are predominantly colocalized with the nuclear bodies promyelocytic leukemia protein (PML) oncogenic domains that are enriched with the PML, SUMO-1, RNA polymerase II, and sumoylatable p45/NF-E2. Chromatin immunoprecipitation assays further showed that the intact sumoylation site of p45/NF-E2 is required for its binding to the DNase I-hypersensitive sites of the β-globin locus control region. Finally, we demonstrated by stable transfection assay that only the wild-type p45, but not its mutant form p45 (K368R), could efficiently rescue β-globin gene expression in the p45-null, erythroid cell line CB3. These data together point to a model of mammalian β-like globin gene activation by sumoylated p45/NF-E2 in erythroid cells.

Chromatin-binding in vivo of the erythroid kruppel-like factor, EKLF, in the murine globin loci

EKLF is an erythroid-specific, zinc finger-containing transcription factor essential for the activation of the mammalian beta globin gene in erythroid cells of definitive lineage. We have prepared a polyclonal anti-mouse EKLF antibody suitable for Western blotting and immunoprecipitation (IP) qualities, and used it to define the expression patterns of the EKLF protein during mouse erythroid development. We have also used this antibody for the chromatin-immunoprecipitation (ChIP) assay. EKLF was found to bind in vivo at both the mouse beta-major-globin promoter and the HS2 site of beta-LCR in the mouse erythroleukemia cells (MEL) in a DMSO-inducible manner. The DMSO-induced bindings of EKLF as well as three other proteins, namely, RNA polymerase II, acetylated histone H3, and methylated histone H3, were not abolished but significantly lowered in CB3, a MEL-derived cell line with null-expression of p45/NF-E2, an erythroid-enriched factor needed for activation of the mammalian globin loci. Interestingly, binding of EKLF in vivo was also detected in the mouse alpha-like globin locus, at the adult alpha globin promoter and its far upstream regulatory element alpha-MRE (HS26). This study provides direct evidence for EKLF-binding in vivo at the major regulatory elements of the mouse beta-like globin gene clusters the data also have interesting implications with respect to the role of EKLF-chromatin interaction in mammalian globin gene regulation.

Attention-deficit hyperactivity disorder, its treatment with medication and the probability of developing a depressive disorder: A nationwide population-based study in Taiwan

OBJECTIVE The purpose of this study is to determine the risk of developing depressive disorders by evaluating children with attention-deficit/hyperactivity disorder (ADHD) in comparison to controls that do not have ADHD, as well as to analyze whether the medications used to treat ADHD, methylphenidate (MPH) and atomoxetine (ATX), influence the risk of depression. METHODS A group of patients newly diagnosed with ADHD (n=71,080) and age- and gender-matching controls (n=71,080) were chosen from Taiwans National Health Insurance database during the period of January 2000 to December 2011. Both the patients and controls were monitored through December 31, 2011. We also explore the potential influence of the length of MPH and ATX treatment on developing depressive disorders. RESULTS The ADHD patients showed a significantly increased probability of developing a depressive disorder when compared to the control group (ADHD: 5.3% vs. CONTROLS 0.7%; aHR, 7.16, 99% CI: 6.28-8.16). Regarding treatment with MPH, a longer MPH use demonstrates significant protective effects against developing a depressive disorder (aOR, 0.91, 99%CI: 0.88-0.94). However, the duration of ATX treatment could not be significantly correlated with the probability of developing a depressive disorder. LIMITATIONS The database employed in this study lacks of comprehensive clinical information for the patients with ADHD. Potential moderating factors between ADHD and depression were not considered in-depth in this study. CONCLUSIONS The results of this study reveal that youths diagnosed with ADHD have a greater risk of developing depressive disorders. Long-term treatment with MPH correlated to the reduced probability of developing a depressive disorder among youths with ADHD.

Attention-deficit/hyperactivity disorder, methylphenidate use and the risk of developing schizophrenia spectrum disorders: A nationwide population-based study in Taiwan

This study estimated the risk of developing psychotic disorders by comparing children with ADHD to non-ADHD controls, and to examine whether methylphenidate (MPH) treatment influences the risks of psychotic disorders. A nationwide cohort of patients who were newly diagnosed with ADHD (n=73,049) and age- and gender-matched controls (n=73,049) were selected from Taiwans National Health Insurance database from January 2000 to December 2011. All participants were observed until December 31, 2011. Cox regression models were used to estimate the effects of ADHD diagnosis and MPH use on subsequent outcomes. Having a diagnosis of any psychotic disorder and of schizophrenia were set as two different outcomes and were analyzed separately. Compared to the control group, the ADHD group showed significantly increased risk of developing any psychotic disorder (adjusted hazard ratio [aHR], 5.20; 95% confidence interval [CI], 4.30-6.30) and schizophrenia (aHR, 4.65; 95% CI, 3.59-6.04). Compared to ADHD patients without psychosis, patients with ADHD who developed psychosis had significantly older age at first diagnosis of ADHD (9.4±3.3years vs. 10.6±4.0years). Among patients with ADHD, MPH use significantly increased the risk of developing any psychotic disorder (aHR, 1.20; 95% CI, 1.04-1.40), but did not increase the risk of developing schizophrenia (aHR, 1.16; 95% CI, 0.94-1.42). The results indicated that previous diagnoses of ADHD are a powerful indicator of developing psychotic disorders. Nevertheless, the specific mechanisms of the relationships between ADHD, MPH use and psychotic disorders need further elucidation in future clinical studies.

Subcellular Transport of EKLF and Switch-On of Murine Adult βmaj Globin Gene Transcription

ABSTRACT Erythroid Krüppel-like factor (EKLF) is an essential transcription factor for mammalian β-like globin gene switching, and it specifically activates transcription of the adult β globin gene through binding of its zinc fingers to the promoter. It has been a puzzle that in the mouse, despite its expression throughout the erythroid development, EKLF activates the adult βmaj globin promoter only in erythroid cells beyond the stage of embryonic day 10.5 (E10.5) but not before. We show here that expression of the mouse βmaj globin gene in the aorta-gonad-mesonephros region of E10.5 embryos and in the E14.5 fetal liver is accompanied by predominantly nuclear localization of EKLF. In contrast, EKLF is mainly cytoplasmic in the erythroid cells of E9.5 blood islands in which βmaj is silenced. Remarkably, in a cultured mouse adult erythroleukemic (MEL) cell line, the activation of the βmaj globin gene by dimethyl sulfoxide (DMSO) or hexamethylene-bis-acetamide (HMBA) induction is also paralleled by a shift of the subcellular location of EKLF from the cytoplasm to the nucleus. Blockage of the nuclear import of EKLF in DMSO-induced MEL cells with a nuclear export inhibitor repressed the transcription of the βmaj globin gene. Transient transfection experiments further indicated that the full-sequence context of EKLF was required for the regulation of its subcellular locations in MEL cells during DMSO induction. Finally, in both the E14.5 fetal liver cells and induced MEL cells, the β-like globin locus is colocalized the PML oncogene domain nuclear body, and concentrated with EKLF, RNA polymerase II, and the splicing factor SC35. These data together provide the first evidence that developmental stage- and differentiation state-specific regulation of the nuclear transport of EKLF might be one of the steps necessary for the switch-on of the mammalian adult β globin gene transcription.

Itch regulates p45/NF-E2 in vivo by Lys63-linked ubiquitination

The hematopoietic-specific transcription factor p45/NF-E2 is an important transcriptional activator in the erythroid and megakaryocytic lineages. We describe the first in vivo evidence for the interaction between p45/NF-E2 and the E3 ubiquitin ligase Itch, and the subsequent ubiquitination of p45/NF-E2 by Itch. Interestingly, Itch suppressed the transactivation activity of p45/NF-E2 by adding a Lys63-linked polyubiquitin chain. Confocal microscopy revealed that ubiquitinated p45/NF-E2 became localized in the cytoplasm when Itch was over-expressed. Thus, Itch-mediated ubiquitination of p45/NF-E2 does not target the protein for proteasomal degradation, but instead retains p45/NF-E2 in the cytoplasm, where it cannot function as a transactivator. Finally, we suggest that this Itch-dependent p45/NF-E2 ubiquitination mechanism may regulate NF-E2 function during the development of hematopoietic cell lineages.

Attention-deficit hyperactivity disorder, its pharmacotherapy, and the risk of developing bipolar disorder: A nationwide population-based study in Taiwan

UNLABELLED In this study, we aimed to evaluate the relationship between attention-deficit/hyperactivity disorder (ADHD) during childhood and subsequent diagnoses of bipolar disorder (BD), as well as to determine whether the pharmacotherapy for ADHD (methylphenidate and atomoxetine) influence the risks of developing BD. A nationwide cohort of patients newly diagnosed with ADHD (n = 144,920) and age- and gender-matching controls (n = 144,920) were found in Taiwans National Health Insurance database from January 2000 to December 2011. Both patients and controls were observed until December 31, 2011. To determine the effect that the duration of methylphenidate and atomoxetine exposure had on BD, the difference in the risk of developing BD was compared among non-users, short-term users (≤ 365 days), and long-term users (>365 days). In comparison to the control group, the ADHD group showed a significantly increased risk of developing BD (ADHD: 2.1% vs. CONTROLS 0.4%; aHR: 7.85, 95% CI: 7.09-8.70), and had a younger mean age at the time of first diagnosis (ADHD: 12.0 years vs. CONTROLS 18.8 years). Compared to ADHD patients that had never taken methylphenidate, patients with long-term use of methylphenidate were less likely to be diagnosed with BD (aOR: 0.72, 95% CI: 0.65-0.80). However, the duration of exposure to atomoxetine did not have a significant relationship to a BD diagnosis. The results suggested that a previous diagnosis of ADHD was a powerful indicator of BD, particularly juvenile-onset BD. Nevertheless, the exact mechanisms of the relationships among ADHD, its pharmacotherapy, and BD require further clarification in the future.

Risk of mortality among patients treated with antipsychotic medications a nationwide population-based study in Taiwan

Abstract In this nationwide population-based study, we examined whether haloperidol exposure is associated with a higher risk of mortality than are other antipsychotic medications. Patients who newly received monotherapy with chlorpromazine (n = 2133), haloperidol (n = 4454), quetiapine (n = 1513), and risperidone (n = 1046) between January 1, 2001, and December 31, 2011, were selected from a random sample of the 1 million enrollees of the Taiwan National Health Insurance Research Database. The association between antipsychotic prescription and mortality was estimated through Cox proportional hazard regression. To examine the mortality rates of antipsychotics at different exposure durations, we compared the differences among short-term (⩽30 days), midterm (31–90 days), and long-term (>90 days) antipsychotic use. The mortality rates during the follow-up among the chlorpromazine, haloperidol, quetiapine, and risperidone groups were 17.4%, 45.5%, 26.8%, and 25.9%, respectively. The mortality risk among patients receiving haloperidol was the highest within 30 days of the prescription, after which the risk reduced rapidly. Compared with the patients receiving chlorpromazine, the mortality risk was higher in short-term (adjusted hazard ratio, 2.11; 95% confidence interval, 1.87–2.39) and midterm haloperidol users (1.86; 1.54–2.25) than in long-term users (0.99; 0.61–1.61). In conclusion, haloperidol use is associated with higher mortality risk than other antipsychotic medications. The mortality risk varies according to the duration of drug exposure. Underlying characteristics and medical conditions may influence the estimation of the mortality risk. Clinicians should pay attention to the mortality risk when prescribing antipsychotic medications, particularly for the elderly and critically ill patients.

Tight Regulation of a Timed Nuclear Import Wave of EKLF by PKCθ and FOE during Pro-E to Baso-E Transition

Erythropoiesis is a highly regulated process during which BFU-E are differentiated into RBCs through CFU-E, Pro-E, PolyCh-E, OrthoCh-E, and reticulocyte stages. Uniquely, most erythroid-specific genes are activated during the Pro-E to Baso-E transition. We show that a wave of nuclear import of the erythroid-specific transcription factor EKLF occurs during the Pro-E to Baso-E transition. We further demonstrate that this wave results from a series of finely tuned events, including timed activation of PKCθ, phosphorylation of EKLF at S68 by P-PKCθ(S676), and sumoylation of EKLF at K74. The latter EKLF modifications modulate its interactions with a cytoplasmic ankyrin-repeat-protein FOE and importinβ1, respectively. The role of FOE in the control of EKLF nuclear import is further supported by analysis of the subcellular distribution patterns of EKLF in FOE-knockout mice. This study reveals the regulatory mechanisms of the nuclear import of EKLF, which may also be utilized in the nuclear import of other factors.

Impact of negative media publicity on attention-deficit/hyperactivity disorder medication in Taiwan.

This study explores trends in attention‐deficit/hyperactivity disorder (ADHD) medications in Taiwan from 2000 to 2011 and whether negative media coverage of Ritalin in January 2010 impacted ADHD prescriptions throughout the country.