ABSTRACT
Batten disease is characterized by early-onset blindness, juvenile dementia and death during the second decade of life. The most common genetic causes are mutations in the CLN3 gene encoding a lysosomal protein. There are currently no therapies targeting the progression of the disease, mostly due to the lack of knowledge about the disease mechanisms. To gain insight into the impact of CLN3 loss on cellular signaling and organelle function, we generated CLN3 knock-out cells in a human cell line (CLN3-KO), and performed RNA sequencing to obtain the cellular transcriptome. Following a multi-dimensional transcriptome analysis, we identified the transcriptional regulator YAP1 as a major driver of the transcriptional changes observed in CLN3-KO cells. We further observed that YAP1 pro-apoptotic signaling is hyperactive as a consequence of CLN3 functional loss in retinal pigment epithelia cells, and in the hippocampus and thalamus of CLN3exΔ7/8 mice, an established model of Batten disease. Loss of CLN3 activates YAP1 by a cascade of events that starts with the inability of releasing glycerophosphodiesthers from CLN3-KO lysosomes, which leads to perturbations in the lipid content of the nuclear envelope and nuclear dysmorphism. This results in increased number of DNA lesions, activating the kinase c-Abl, which phosphorylates YAP1, stimulating its pro-apoptotic signaling. Altogether, our results highlight a novel organelle crosstalk paradigm in which lysosomal metabolites regulate nuclear envelope content, nuclear shape and DNA homeostasis. This novel molecular mechanism underlying the loss of CLN3 in mammalian cells and tissues may open new c-Abl-centric therapeutic strategies to target Batten disease.
ABSTRACT
Background: Perindopril is an ACE inhibitor that aids in both blood pressure regulation and homocysteine reduction. Objectives: Our study aimed to evaluate the results of controlling blood pressure and blood homocysteine levels by perindopril in patients with primary hypertension. Materials and Methods: A cross-sectional descriptive study with a longitudinal follow-up was conducted on 105 primary hypertensive patients treated with perindopril. Results: The results of our study showed that after 6 weeks of treatment with perindopril, the proportion of patients with the target blood pressure (BP) level accounted for 70.5%, the rate of grade 1 hypertension decreased from 61.0% to 25.7%, grade 2 blood pressure decreased from 17.1% to 3.8%, and there was no case of grade 3 hypertension. At the same time, we also found that the rate of BP control in the group of patients who controlled Hcy below a threshold of 15 µmol/L was significantly higher than in the other group (p < 0.05). Concerning the efficacy of decreasing homocysteine in blood, we discovered that after 6 weeks of treatment with perindopril, the proportion of patients with elevated homocysteine reduced considerably from 74.3% to 40% (p < 0.05). In addition, the homocysteine concentration was 4.33 mol/L lower after treatment than before treatment (95% CI: 3.69-4.97) (p < 0.05). Conclusion: Perindopril helps control blood pressure and reduces blood homocysteine levels in patients with primary hypertension.
ABSTRACT
Batten disease, one of the most devastating types of neurodegenerative lysosomal storage disorders, is caused by mutations in CLN3. Here, we show that CLN3 is a vesicular trafficking hub connecting the Golgi and lysosome compartments. Proteomic analysis reveals that CLN3 interacts with several endo-lysosomal trafficking proteins, including the cation-independent mannose 6 phosphate receptor (CI-M6PR), which coordinates the targeting of lysosomal enzymes to lysosomes. CLN3 depletion results in mis-trafficking of CI-M6PR, mis-sorting of lysosomal enzymes, and defective autophagic lysosomal reformation. Conversely, CLN3 overexpression promotes the formation of multiple lysosomal tubules, which are autophagy and CI-M6PR-dependent, generating newly formed proto-lysosomes. Together, our findings reveal that CLN3 functions as a link between the M6P-dependent trafficking of lysosomal enzymes and lysosomal reformation pathway, explaining the global impairment of lysosomal function in Batten disease.
Subject(s)
Membrane Glycoproteins , Neuronal Ceroid-Lipofuscinoses , Humans , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Neuronal Ceroid-Lipofuscinoses/genetics , Neuronal Ceroid-Lipofuscinoses/metabolism , Receptor, IGF Type 2/genetics , Receptor, IGF Type 2/metabolism , Proteomics , Molecular Chaperones/metabolism , Lysosomes/metabolism , Hydrolases/metabolism , AutophagySubject(s)
Histiocytic Necrotizing Lymphadenitis , Lymphohistiocytosis, Hemophagocytic , Macrophage Activation Syndrome , Histiocytic Necrotizing Lymphadenitis/complications , Histiocytic Necrotizing Lymphadenitis/diagnosis , Humans , Lymphohistiocytosis, Hemophagocytic/diagnosis , Lymphohistiocytosis, Hemophagocytic/etiology , Staphylococcus epidermidisABSTRACT
BACKGROUND: Adherence to antiepileptic drugs (AEDs) remains the primary management tool to prevent recurrent seizures in patients with epilepsy. Adverse events associated with AEDs could have an impact on adherence and result in treatment failures. OBJECTIVE: The goal of this study was to assess the association between adverse events and discontinuation of AEDs for AED-naïve patients with epilepsy. Our second objective was to estimate the economic burden of AED discontinuation. METHODS: We retrospectively analyzed IBM MarketScan administrative data from 2014 to 2017. The cohort consisted of new users of AEDs with an epilepsy diagnosis and with two or more subsequent AED claims. Outpatient and inpatient cohorts were analyzed separately. Adverse events were identified by injury codes (E-CODES) or by International Classification of Diseases, Ninth/Tenth Edition (ICD-9/10) codes for disease manifestations reported in the literature or product inserts (LADE). Discontinuation of AEDs was defined as a gap of ≥ 60 days without a refill. All cost comparisons were based on 1:1 propensity-score matching. Associations between adverse events and discontinuation were estimated using logistic regression, adjusting for predefined covariates such as age, sex, Charlson Comorbidity Index, insurance type, and AED type. RESULTS: The overall discontinuation rate was 9% (E-CODES rate was 0.1% and LADE rate was 27%). The discontinued group was older (56.1 vs. 52.8 years; p < 0.0001). Adults aged ≥ 65 years had the highest discontinuation rate (11%). Patients who discontinued had fewer AED claims (6.8 vs. 9.2; p < 0.0001), more outpatient claims (19.3 vs. 17.8; p < 0.0001), and longer hospital stays (6.6 vs. 5.3 days; p < 0.0001). Differences in daily outpatient costs between patients with and without adverse events were statistically significant (E-CODES $US213 vs. 105; p = 0.001; LADE $US188 vs. 161; p < 0.0001). Additionally, total cost of AEDs in the outpatient cohort was higher for patients with adverse events (E-CODES and LADE). There was no association between E-CODES and AED discontinuation; however, there was a positive association between LADE and discontinuation in the outpatient cohort but a negative association in the inpatient cohort. CONCLUSION: We found that total costs of prescriptions claimed and total costs of outpatient visits among the outpatient cohort were higher for those with adverse drug events than for those without. An association between adverse events and discontinuation was inconclusive because it depended on the target population and how the adverse events were identified.
ABSTRACT
Objective. To compare first-year student pharmacists and nursing students with respect to their spirituality and perceptions of the role of spirituality in professional education and practice. Methods. This was a five-year, cross-sectional study. All first-year student pharmacists and nursing students were invited to participate in the survey during the first week of the fall semester in 2012 through 2016. Descriptive and inferential statistics were used to analyze the data. Results. A total of 1,084 students participated, including 735 student pharmacists and 349 nursing students. Significant differences in baseline demographics were noted between the groups. Students in both groups reported having frequent spiritual experiences. A significantly larger percentage of nursing students reported these experiences compared to student pharmacists. Furthermore, compared with student pharmacists, nursing students were more likely to anticipate that spirituality would play a role in their academic course work (76% vs 58%) and professional practice (90% vs 74%). Conclusion. Student pharmacists and nursing students reported having frequent spiritual experiences, and both groups anticipated that spirituality would be incorporated into their education and professional practice.
Subject(s)
Perception , Spirituality , Students, Nursing , Students, Pharmacy , Adult , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Young AdultABSTRACT
It is well established that pluripotent stem cells in fetal and postnatal liver (LPCs) can differentiate into both hepatocytes and cholangiocytes. However, the signaling pathways implicated in the differentiation of LPCs are still incompletely understood. Transcription Factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy, is known to be involved in osteoblast and myeloid differentiation, but its role in lineage commitment in the liver has not been investigated. Here we show that during development and upon regeneration TFEB drives the differentiation status of murine LPCs into the progenitor/cholangiocyte lineage while inhibiting hepatocyte differentiation. Genetic interaction studies show that Sox9, a marker of precursor and biliary cells, is a direct transcriptional target of TFEB and a primary mediator of its effects on liver cell fate. In summary, our findings identify an unexplored pathway that controls liver cell lineage commitment and whose dysregulation may play a role in biliary cancer.
Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Cell Lineage , Liver/cytology , Liver/physiology , Regeneration/physiology , Animals , Bile Duct Neoplasms/pathology , Bile Ducts/metabolism , Cell Differentiation , Cell Proliferation , Cholangiocarcinoma/pathology , Down-Regulation/genetics , Hepatocytes/cytology , Mice, Inbred C57BL , Mice, Transgenic , Models, Biological , Phenotype , Promoter Regions, Genetic/genetics , Protein Binding , SOX9 Transcription Factor/genetics , SOX9 Transcription Factor/metabolism , Spheroids, Cellular/cytology , Stem Cells/cytology , Stem Cells/metabolism , Up-Regulation/geneticsABSTRACT
Autophagy and energy metabolism are known to follow a circadian pattern. However, it is unclear whether autophagy and the circadian clock are coordinated by common control mechanisms. Here, we show that the oscillation of autophagy genes is dependent on the nutrient-sensitive activation of TFEB and TFE3, key regulators of autophagy, lysosomal biogenesis, and cell homeostasis. TFEB and TFE3 display a circadian activation over the 24-h cycle and are responsible for the rhythmic induction of genes involved in autophagy during the light phase. Genetic ablation of TFEB and TFE3 in mice results in deregulated autophagy over the diurnal cycle and altered gene expression causing abnormal circadian wheel-running behavior. In addition, TFEB and TFE3 directly regulate the expression of Rev-erbα (Nr1d1), a transcriptional repressor component of the core clock machinery also involved in the regulation of whole-body metabolism and autophagy. Comparative analysis of the cistromes of TFEB/TFE3 and REV-ERBα showed an extensive overlap of their binding sites, particularly in genes involved in autophagy and metabolic functions. These data reveal a direct link between nutrient and clock-dependent regulation of gene expression shedding a new light on the crosstalk between autophagy, metabolism, and circadian cycles.
Subject(s)
Autophagy , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/physiology , Circadian Clocks , Energy Metabolism , Nutrients/physiology , Animals , Autophagy/drug effects , Autophagy/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/drug effects , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Binding Sites , Cells, Cultured , Circadian Clocks/drug effects , Circadian Clocks/genetics , Circadian Rhythm/drug effects , Circadian Rhythm/physiology , Energy Metabolism/drug effects , Energy Metabolism/genetics , Gene Expression Regulation , HEK293 Cells , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Nuclear Receptor Subfamily 1, Group D, Member 1/genetics , Nuclear Receptor Subfamily 1, Group D, Member 1/physiology , Nutrients/pharmacology , Transcription Factors/drug effects , Transcription Factors/genetics , Transcription Factors/physiologyABSTRACT
INTRODUCTION: Chlorine exposure can lead to pulmonary obstruction, reactive airway dysfunction syndrome, acute respiratory distress syndrome and, rarely, death. OBJECTIVE: We performed a systematic review of published animal and human data regarding the management of chlorine exposure. METHODS: Three databases were searched from 2007 to 2017 using the following keywords "("chlorine gas" OR "chlorine-induced" OR" chlorine-exposed") AND ("therapy" OR "treatment" OR "post-exposure")". Forty-five relevant papers were found: 22 animal studies, 6 reviews, 19 case reports and 1 human randomized controlled study. General management: Once the casualty has been removed from the source of exposure and adequately decontaminated, chlorine-exposed patients should receive supportive care. Humidified oxygen: If dyspnea and hypoxemia are present, humidified oxygen should be administered. Inhaled bronchodilators: The use of nebulized or inhaled bronchodilators to counteract bronchoconstriction is standard therapy, and the combination of ipratropium bromide with beta2-agonists effectively reversed bronchoconstriction, airway irritation and increased airway resistance in experimental studies. Inhaled sodium bicarbonate: In a randomized controlled trial, humidified oxygen, intravenous prednisolone and inhaled salbutamol were compared with nebulized sodium bicarbonate. The only additional benefit of sodium bicarbonate was to increase the forced expiratory volume in one second, 2 and 4 h after administration. Corticosteroids: Dexamethasone 100 mg/kg intraperitoneally (IP) reduced lung edema when given within 1 h of chlorine inhalation and when administered within 6 h significantly decreased (p < 0.01) the leukocyte count in the bronchoalveolar lavage (BAL). As corticosteroids were never given alone in clinical studies, it is impossible to assess whether they had an additional beneficial effect. Antioxidants: An ascorbic acid/deferoxamine combination (equivalent to 100 mg/kg and 15 mg/kg, respectively) was administered intramuscularly 1 h after chlorine exposure, then every 12 h up to 60 h, then as an aerosol, and produced a significant reduction (p < 0.05) in BAL leukocytes and a significant reduction (p < 0.007) in mortality at 72 h. The single clinical case reported was uninterpretable. Sodium nitrite: Sodium nitrite 10 mg/kg intramuscularly (IM), 30 min post-chlorine exposure in mice and rabbits significantly reduced (p < 0.01) the number of leukocytes and the protein concentration in BAL and completely reversed mortality in rabbits and decreased mortality by about 50% in mice. No clinical studies have reported the use of sodium nitrite. Dimethylthiourea: Dimethylthiourea 100 mg/kg IP significantly decreased (p < 0.05) lymphocytes and neutrophils in BAL fluid 24 h after chlorine exposure in experimental studies. No clinical studies have been undertaken. AEOL 10150: Administration of AEOL10150 5 mg/kg IP at 1 h and 9 h post-chlorine exposure reduced significantly the neutrophil (p < 0.001) and macrophage (p < 0.05) bronchoalveolar cell counts. Transient receptor potential vanilloid 4 (TRPV4): IM or IP TRPV4 reduced significantly (p < 0.001) bronchoalveolar neutrophil and macrophage counts to baseline at 24 h. No clinical studies have been performed. Reparixin and triptolide: In experimental studies, triptolide 100-1000 µg/kg IP 1 h post-exposure caused a significant decrease (p < 0.001) in bronchoalveolar neutrophils, whereas reparixin 15 mg/kg IP 1 h post-exposure produced no benefit. Rolipram: Nanoemulsion formulated rolipram administered intramuscularly returned airway resistance to baseline. Rolipram (40%)/poly(lactic-co-glycolic acid) (60%) 0.36 mg/mouse given intramuscularly 1 h post-exposure significantly reduced (p < 0.05) extravascular lung water by 20% at t + 6 h. Prophylactic antibiotics: Studies in patients have failed to demonstrate benefit. Sevoflurane: Sevoflurane has been used in one intubated patient in addition to beta2-agonists. Although the peak inspiratory pressure was decreased after 60 min, the role of sevofluorine is not known. CONCLUSIONS: Various therapies seem promising based on animal studies or case reports. However, these recommendations are based on low-level quality data. A systematic list of outcomes to monitor and improve may help to design optimal therapeutic protocols to manage chlorine-exposed patients.
Subject(s)
Acute Lung Injury/chemically induced , Chlorine/toxicity , Inhalation Exposure/adverse effects , Acute Lung Injury/therapy , Animals , Emergency Medical Services/methods , HumansABSTRACT
The circadian clock operates as intrinsic time-keeping machinery to preserve homeostasis in response to the changing environment. While food is a known zeitgeber for clocks in peripheral tissues, it remains unclear how lack of food influences clock function. We demonstrate that the transcriptional response to fasting operates through molecular mechanisms that are distinct from time-restricted feeding regimens. First, fasting affects core clock genes and proteins, resulting in blunted rhythmicity of BMAL1 and REV-ERBα both in liver and skeletal muscle. Second, fasting induces a switch in temporal gene expression through dedicated fasting-sensitive transcription factors such as GR, CREB, FOXO, TFEB, and PPARs. Third, the rhythmic genomic response to fasting is sustainable by prolonged fasting and reversible by refeeding. Thus, fasting imposes specialized dynamics of transcriptional coordination between the clock and nutrient-sensitive pathways, thereby achieving a switch to fasting-specific temporal gene regulation.
Subject(s)
Circadian Rhythm/physiology , Fasting/physiology , Liver/physiology , Muscle, Skeletal/physiology , Animals , CLOCK Proteins/metabolism , Circadian Clocks/genetics , Feeding Behavior , Gene Expression Regulation , Male , Mice, Inbred C57BL , Organ Specificity/genetics , Time Factors , Transcription Factors/metabolismABSTRACT
TFE3 and TFEB are members of the MiT family of HLH-leucine zipper transcription factors. Recent studies demonstrated that they bind overlapping sets of promoters and are post-transcriptionally regulated through a similar mechanism. However, while Tcfeb knockout (KO) mice die during early embryonic development, no apparent phenotype was reported in Tfe3 KO mice. Thus raising the need to characterize the physiological role of TFE3 and elucidate its relationship with TFEB TFE3 deficiency resulted in altered mitochondrial morphology and function both in vitro and in vivo due to compromised mitochondrial dynamics. In addition, Tfe3 KO mice showed significant abnormalities in energy balance and alterations in systemic glucose and lipid metabolism, resulting in enhanced diet-induced obesity and diabetes. Conversely, viral-mediated TFE3 overexpression improved the metabolic abnormalities induced by high-fat diet (HFD). Both TFEB overexpression in Tfe3 KO mice and TFE3 overexpression in Tcfeb liver-specific KO mice (Tcfeb LiKO) rescued HFD-induced obesity, indicating that TFEB can compensate for TFE3 deficiency and vice versa Analysis of Tcfeb LiKO/Tfe3 double KO mice demonstrated that depletion of both TFE3 and TFEB results in additive effects with an exacerbation of the hepatic phenotype. These data indicate that TFE3 and TFEB play a cooperative, rather than redundant, role in the control of the adaptive response of whole-body metabolism to environmental cues such as diet and physical exercise.
Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Energy Metabolism , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Diet, High-Fat/adverse effects , Glucose/metabolism , Lipid Metabolism , Male , Mice, Inbred C57BL , Mice, Knockout , Mitochondrial Dynamics , Physical Conditioning, Animal , Up-RegulationABSTRACT
In massive catastrophic events, occupational health practitioners are more and more frequently involved in the management of such situations. We aim to describe the multiple aspects of the role that occupational health practitioners might play, by focusing on the recent example of the Paris terrorist attack of November 2015. During and after the Paris attack, occupational practitioners, in collaboration with emergency and security professionals, were involved in psychological care, assembling information, follow-up, return-to-work, and improving in-company safety plans. Based on this experience and other industrial disasters, we distinguish three phases: the critical phase, the post-critical phase, and the anticipation phase. In the critical phase, the occupational practitioner cares for patients before the emergency professionals take charge, initiates the psychological management, and may also play an organizational role for company health aspects. In the post-critical phase, he or she would be involved in monitoring those affected by the events and participate in preventing, to the extent possible, posttraumatic stress disorder, helping victims in the return-to-work process, and improving procedures and organizing drills. In addition to their usual work of primary prevention, occupational practitioners should endeavor to improve preparedness in the anticipation phase, by taking part in contingency planning, training in first aid, and defining immediately applicable protocols. In conclusion, recent events have highlighted the essential role of occupational health services in anticipation of a crisis, management during the crisis, and follow-up.
ABSTRACT
The activation of transcription factors is critical to ensure an effective defense against pathogens. In this study we identify a critical and complementary role of the transcription factors TFEB and TFE3 in innate immune response. By using a combination of chromatin immunoprecipitation, CRISPR-Cas9-mediated genome-editing technology, and in vivo models, we determined that TFEB and TFE3 collaborate with each other in activated macrophages and microglia to promote efficient autophagy induction, increased lysosomal biogenesis, and transcriptional upregulation of numerous proinflammatory cytokines. Furthermore, secretion of key mediators of the inflammatory response (CSF2, IL1B, IL2, and IL27), macrophage differentiation (CSF1), and macrophage infiltration and migration to sites of inflammation (CCL2) was significantly reduced in TFEB and TFE3 deficient cells. These new insights provide us with a deeper understanding of the transcriptional regulation of the innate immune response.
Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Immunity, Innate , Macrophages/metabolism , Animals , Autophagy , Cell Nucleus/metabolism , Cytosol/metabolism , Female , Gene Expression Regulation , HEK293 Cells , Humans , Inflammation , Macrophage Activation , Male , Mice , Microglia/metabolism , RAW 264.7 CellsABSTRACT
Attenuated auto-lysosomal system has been associated with Alzheimer disease (AD), yet all underlying molecular mechanisms leading to this impairment are unknown. We show that the amino acid sensing of mechanistic target of rapamycin complex 1 (mTORC1) is dysregulated in cells deficient in presenilin, a protein associated with AD. In these cells, mTORC1 is constitutively tethered to lysosomal membranes, unresponsive to starvation, and inhibitory to TFEB-mediated clearance due to a reduction in Sestrin2 expression. Normalization of Sestrin2 levels through overexpression or elevation of nuclear calcium rescued mTORC1 tethering and initiated clearance. While CLEAR network attenuation in vivo results in buildup of amyloid, phospho-Tau, and neurodegeneration, presenilin-knockout fibroblasts and iPSC-derived AD human neurons fail to effectively initiate autophagy. These results propose an altered mechanism for nutrient sensing in presenilin deficiency and underline an importance of clearance pathways in the onset of AD.
Subject(s)
Presenilins/genetics , Alzheimer Disease/metabolism , Amino Acids/metabolism , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Brain/metabolism , Brain/pathology , Calcium/metabolism , Cell Nucleus/metabolism , Cells, Cultured , Gene Regulatory Networks , Humans , Mechanistic Target of Rapamycin Complex 1 , Mice , Mice, Knockout , Multiprotein Complexes/metabolism , Nuclear Proteins/metabolism , Nutritional Physiological Phenomena , Peroxidases , Presenilins/metabolism , TOR Serine-Threonine Kinases/metabolismABSTRACT
BACKGROUND: Behavioral interventions for obesity are commonly delivered in groups, although the effect of group size on weight loss has not been empirically evaluated. This behavioral weight loss trial compared the 6- and 12-month weight changes associated with interventions delivered in a large group (LG) or small groups (SG). METHODS: Obese adults (N = 66; mean age = 50 years; mean BMI = 36.5 kg/m2; 47% African American; 86% women) recruited from a health maintenance organization were randomly assigned to: (1) LG treatment (30 members/group), or (2) SG treatment (12 members/group). Conditions were comparable in frequency and duration of treatment, which included 24 weekly group sessions (months 1-6) followed by six monthly extended care contacts (months 7-12). A mixed effects model with unstructured covariance matrix was applied to analyze the primary outcome of weight change while accounting for baseline weight and dependence among participants' measurements over time. RESULTS: SG participants lost significantly more weight than LG participants at Month 6 (-6.5 vs. -3.2 kg; p = 0.03) and Month 12 (-7.0 vs. -1.7 kg; p < 0.002). SG participants reported better treatment engagement and self-monitoring adherence at Months 6 and 12, ps < 0.04, with adherence fully mediating the relationship between group size and weight loss. CONCLUSIONS: Receiving obesity treatment in smaller groups may promote greater weight loss and weight loss maintenance. This effect may be due to improved adherence facilitated by SG interactions. These novel findings suggest that the perceived efficiency of delivering behavioral weight loss treatment to LGs should be balanced against the potentially better outcomes achieved by a SG approach.
Subject(s)
Feeding Behavior , Obesity/therapy , Weight Loss , Weight Reduction Programs/methods , Adult , Black or African American , Body Mass Index , Female , Florida , Follow-Up Studies , Health Behavior , Health Maintenance Organizations , Humans , Life Style , Male , Middle Aged , Motor Activity , Socioeconomic Factors , Treatment Outcome , Young AdultABSTRACT
The lysosomal-autophagic pathway is activated by starvation and plays an important role in both cellular clearance and lipid catabolism. However, the transcriptional regulation of this pathway in response to metabolic cues is uncharacterized. Here we show that the transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy, is induced by starvation through an autoregulatory feedback loop and exerts a global transcriptional control on lipid catabolism via Ppargc1α and Ppar1α. Thus, during starvation a transcriptional mechanism links the autophagic pathway to cellular energy metabolism. The conservation of this mechanism in Caenorhabditis elegans suggests a fundamental role for TFEB in the evolution of the adaptive response to food deprivation. Viral delivery of TFEB to the liver prevented weight gain and metabolic syndrome in both diet-induced and genetic mouse models of obesity, suggesting a new therapeutic strategy for disorders of lipid metabolism.
Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Lipid Metabolism , Metabolic Syndrome/metabolism , Obesity/metabolism , Starvation/metabolism , Animals , Autophagy/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/pharmacology , Caenorhabditis elegans/metabolism , Cell Line, Tumor , Energy Metabolism , Feedback, Physiological , Gene Expression Regulation , HeLa Cells , Homeostasis , Humans , Liver/metabolism , Lysosomes/genetics , Male , Metabolic Syndrome/genetics , Metabolic Syndrome/prevention & control , Mice , Mice, Inbred C57BL , Mice, Transgenic , Obesity/genetics , PPAR alpha/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , Starvation/genetics , Trans-Activators/metabolism , Transcription Factors , Transcription, Genetic , Weight GainABSTRACT
The lysosome plays a key role in cellular homeostasis by controlling both cellular clearance and energy production to respond to environmental cues. However, the mechanisms mediating lysosomal adaptation are largely unknown. Here, we show that the Transcription Factor EB (TFEB), a master regulator of lysosomal biogenesis, colocalizes with master growth regulator mTOR complex 1 (mTORC1) on the lysosomal membrane. When nutrients are present, phosphorylation of TFEB by mTORC1 inhibits TFEB activity. Conversely, pharmacological inhibition of mTORC1, as well as starvation and lysosomal disruption, activates TFEB by promoting its nuclear translocation. In addition, the transcriptional response of lysosomal and autophagic genes to either lysosomal dysfunction or pharmacological inhibition of mTORC1 is suppressed in TFEB-/- cells. Interestingly, the Rag GTPase complex, which senses lysosomal amino acids and activates mTORC1, is both necessary and sufficient to regulate starvation- and stress-induced nuclear translocation of TFEB. These data indicate that the lysosome senses its content and regulates its own biogenesis by a lysosome-to-nucleus signalling mechanism that involves TFEB and mTOR.
Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Cell Nucleus/physiology , Lysosomes/physiology , Proteins/metabolism , Signal Transduction , Animals , Cell Line , Humans , Immunoprecipitation , Lysosomal Membrane Proteins/metabolism , Lysosomes/metabolism , Mechanistic Target of Rapamycin Complex 1 , Mice , Mice, Knockout , Microscopy, Fluorescence , Models, Biological , Multiprotein Complexes , Protein Binding , Protein Interaction Mapping , TOR Serine-Threonine KinasesABSTRACT
The developmental role of the T-box transcription factor Tbx1 is exquisitely dosage-sensitive. In this study, we performed a microarray-based transcriptome analysis of E9.5 embryo tissues across a previously generated Tbx1 mouse allelic series. This analysis identified several genes whose expression was affected by Tbx1 dosage. Interestingly, we found that the expression of the gene encoding the cardiogenic transcription factor Mef2c was negatively correlated to Tbx1 dosage. In vivo data revealed Mef2c up-regulation in the second heart field (SHF) of Tbx1 null mutant embryos compared with wild-type littermates at E9.5. Conversely, Mef2c expression was decreased in the SHF and in somites of Tbx1 gain-of-function mutants. These results are consistent with the described role of Tbx1 in suppressing cardiac progenitor cell differentiation and indicate also a negative effect of Tbx1 on Mef2c during skeletal muscle differentiation. We show that Tbx1 occupies conserved regulatory regions of the Mef2c locus, suggesting a direct effect on Mef2c transcription. However, we also show that Tbx1 interferes with the Gata4â Mef2c regulatory pathway. Overall, our study uncovered a target of Tbx1 with critical developmental roles, so highlighting the power of the dosage gradient approach that we used.
Subject(s)
Myogenic Regulatory Factors/genetics , T-Box Domain Proteins/genetics , Alleles , Animals , Cell Differentiation , Genotype , MEF2 Transcription Factors , Mice , Mice, Transgenic , Myogenic Regulatory Factors/metabolism , Phenotype , T-Box Domain Proteins/metabolism , Transcriptome , Transfection , Up-RegulationABSTRACT
Autophagy is a cellular catabolic process that relies on the cooperation of autophagosomes and lysosomes. During starvation, the cell expands both compartments to enhance degradation processes. We found that starvation activates a transcriptional program that controls major steps of the autophagic pathway, including autophagosome formation, autophagosome-lysosome fusion, and substrate degradation. The transcription factor EB (TFEB), a master gene for lysosomal biogenesis, coordinated this program by driving expression of autophagy and lysosomal genes. Nuclear localization and activity of TFEB were regulated by serine phosphorylation mediated by the extracellular signal-regulated kinase 2, whose activity was tuned by the levels of extracellular nutrients. Thus, a mitogen-activated protein kinase-dependent mechanism regulates autophagy by controlling the biogenesis and partnership of two distinct cellular organelles.
Subject(s)
Autophagy , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Cell Nucleus/metabolism , Lysosomes/metabolism , Active Transport, Cell Nucleus , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , COS Cells , Cells, Cultured , Chlorocebus aethiops , Cytoplasm/metabolism , Gene Expression Regulation , HeLa Cells , Humans , Liver/metabolism , MAP Kinase Signaling System , Mice , Mice, Transgenic , Microtubule-Associated Proteins/metabolism , Mitogen-Activated Protein Kinase 1/metabolism , Phagosomes/metabolism , Phosphorylation , RNA Interference , Transcription, Genetic , Up-RegulationABSTRACT
Tbx1 is the candidate gene of DiGeorge syndrome and is required in humans and mice for the development of the cardiac outflow tract (OFT) and aortic arch arteries. Loss of function mutants present with reduced cell proliferation and premature differentiation of cardiac progenitor cells of the second heart field (SHF). Tbx1 regulates Fgf8 expression hence the hypothesis that the proliferation impairment may contribute to the heart phenotype of mutants. Here we show that forced Fgf8 expression modifies and partially rescues the OFT septation defects of Tbx1 mutants but only if there is some residual expression of Tbx1. This genetic experiment suggests that Tbx1, directly or indirectly, affects tissue response to Fgf8. Indeed, Tbx1(-/-) mouse embryonic fibroblasts were unable to respond to Fgf8 added to the culture media and showed defective response of Erk1/2 and Rsk1. Our data suggest a coordinated pathway modulating Fgf8 ligand expression and tissue response to it in the SHF.