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1.
J Cell Physiol ; 239(4): e31204, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38419397

ABSTRACT

Mitochondria and endoplasmic reticulum (ER) contact sites (MERCs) are protein- and lipid-enriched hubs that mediate interorganellar communication by contributing to the dynamic transfer of Ca2+, lipid, and other metabolites between these organelles. Defective MERCs are associated with cellular oxidative stress, neurodegenerative disease, and cardiac and skeletal muscle pathology via mechanisms that are poorly understood. We previously demonstrated that skeletal muscle-specific knockdown (KD) of the mitochondrial fusion mediator optic atrophy 1 (OPA1) induced ER stress and correlated with an induction of Mitofusin-2, a known MERC protein. In the present study, we tested the hypothesis that Opa1 downregulation in skeletal muscle cells alters MERC formation by evaluating multiple myocyte systems, including from mice and Drosophila, and in primary myotubes. Our results revealed that OPA1 deficiency induced tighter and more frequent MERCs in concert with a greater abundance of MERC proteins involved in calcium exchange. Additionally, loss of OPA1 increased the expression of activating transcription factor 4 (ATF4), an integrated stress response (ISR) pathway effector. Reducing Atf4 expression prevented the OPA1-loss-induced tightening of MERC structures. OPA1 reduction was associated with decreased mitochondrial and sarcoplasmic reticulum, a specialized form of ER, calcium, which was reversed following ATF4 repression. These data suggest that mitochondrial stress, induced by OPA1 deficiency, regulates skeletal muscle MERC formation in an ATF4-dependent manner.


Subject(s)
Activating Transcription Factor 4 , Neurodegenerative Diseases , Animals , Mice , Activating Transcription Factor 4/genetics , Activating Transcription Factor 4/metabolism , Calcium/metabolism , Endoplasmic Reticulum/metabolism , Endoplasmic Reticulum Stress/genetics , Lipids , Mitochondria/metabolism , Muscle, Skeletal/metabolism , Neurodegenerative Diseases/pathology , Male , Mice, Inbred C57BL , Cells, Cultured , GTP Phosphohydrolases/metabolism
2.
Adv Biol (Weinh) ; 7(10): e2200202, 2023 10.
Article in English | MEDLINE | ID: mdl-37140138

ABSTRACT

Mitochondria respond to metabolic demands of the cell and to incremental damage, in part, through dynamic structural changes that include fission (fragmentation), fusion (merging of distinct mitochondria), autophagic degradation (mitophagy), and biogenic interactions with the endoplasmic reticulum (ER). High resolution study of mitochondrial structural and functional relationships requires rapid preservation of specimens to reduce technical artifacts coupled with quantitative assessment of mitochondrial architecture. A practical approach for assessing mitochondrial fine structure using two dimensional and three dimensional high-resolution electron microscopy is presented, and a systematic approach to measure mitochondrial architecture, including volume, length, hyperbranching, cristae morphology, and the number and extent of interaction with the ER is described. These methods are used to assess mitochondrial architecture in cells and tissue with high energy demand, including skeletal muscle cells, mouse brain tissue, and Drosophila muscles. The accuracy of assessment is validated in cells and tissue with deletion of genes involved in mitochondrial dynamics.


Subject(s)
Mitochondria , Mitochondrial Membranes , Mice , Animals , Mitochondria/metabolism , Mitochondrial Membranes/metabolism , Microscopy, Electron, Scanning , Cells, Cultured
3.
Adv Biol (Weinh) ; 7(6): e2200221, 2023 06.
Article in English | MEDLINE | ID: mdl-36869426

ABSTRACT

Various intracellular degradation organelles, including autophagosomes, lysosomes, and endosomes, work in tandem to perform autophagy, which is crucial for cellular homeostasis. Altered autophagy contributes to the pathophysiology of various diseases, including cancers and metabolic diseases. This paper aims to describe an approach to reproducibly identify and distinguish subcellular structures involved in macroautophagy. Methods are provided that help avoid common pitfalls. How to distinguish between lysosomes, lipid droplets, autolysosomes, autophagosomes, and inclusion bodies are also discussed. These methods use transmission electron microscopy (TEM), which is able to generate nanometer-scale micrographs of cellular degradation components in a fixed sample. Serial block face-scanning electron microscopy is also used to visualize the 3D morphology of degradation machinery using the Amira software. In addition to TEM and 3D reconstruction, other imaging techniques are discussed, such as immunofluorescence and immunogold labeling, which can be used to classify cellular organelles, reliably and accurately. Results show how these methods may be used to accurately quantify cellular degradation machinery under various conditions, such as treatment with the endoplasmic reticulum stressor thapsigargin or ablation of the dynamin-related protein 1.


Subject(s)
Imaging, Three-Dimensional , Lysosomes , Microscopy, Electron, Transmission , Lysosomes/metabolism , Lysosomes/ultrastructure , Autophagy/physiology , Endoplasmic Reticulum
4.
Autophagy ; 18(9): 2161-2177, 2022 09.
Article in English | MEDLINE | ID: mdl-35104184

ABSTRACT

Impairments in macroautophagy/autophagy, which degrades dysfunctional organelles as well as long-lived and aggregate proteins, are associated with several cardiomyopathies; however, the regulation of cardiac autophagy remains insufficiently understood. In this regard, ULK1 and ULK2 are thought to play primarily redundant roles in autophagy initiation, but whether their function is developmentally determined, potentially having an impact on cardiac integrity and function remains unknown. Here, we demonstrate that perinatal loss of ULK1 or ULK2 in cardiomyocytes (cU1-KO and cU2-KO mice, respectively) enhances basal autophagy without altering autophagy machinery content while preserving cardiac function. This increased basal autophagy is dependent on the remaining ULK protein given that perinatal loss of both ULK1 and ULK2 in cU1/2-DKO mice impaired autophagy causing age-related cardiomyopathy and reduced survival. Conversely, adult loss of cardiac ULK1, but not of ULK2 (i.e., icU1-KO and icU2-KO mice, respectively), led to a rapidly developing cardiomyopathy, heart failure and early death. icU1-KO mice had impaired autophagy with robust deficits in mitochondrial respiration and ATP synthesis. Trehalose ameliorated autophagy impairments in icU1-KO hearts but did not delay cardiac dysfunction suggesting that ULK1 plays other critical, autophagy-independent, functions in the adult heart. Collectively, these results indicate that cardiac ULK1 and ULK2 are functionally redundant in the developing heart, while ULK1 assumes a more unique, prominent role in the adult heart.Abbreviations: ATG4: autophagy related 4, cysteine peptidase; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG9: autophagy related 9; ATG13: autophagy related 13; CYCS: Cytochrome C; DNM1L, dynamin 1-like; MAP1LC3A: microtubule-associated protein 1 light chain 3 alpha; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MFN1: mitofusin 1; MFN2: mitofusin 2; MT-CO1: mitochondrially encoded cytochrome c oxidase I; MYH: myosin, heavy polypeptide; NBR1: NBR1 autophagy cargo receptor; NDUFA9: NADH:ubiquinone oxidoreductase subunit A9; OPA1: OPA1, mitochondrial dynamin like GTPase; PPARGC1A, peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; SDHA: succinate dehydrogenase complex, subunit A, flavoprotein (Fp); SQSTM1: sequestosome 1; ULK1: unc-51 like kinase 1; ULK2: unc-51 like kinase 2; UQCRC1: ubiquinol-cytochrome c reductase core protein 1.


Subject(s)
Autophagy , Microtubule-Associated Proteins , Animals , Autophagy-Related Protein-1 Homolog/metabolism , Electron Transport Complex I/metabolism , Mice , Microtubule-Associated Proteins/metabolism , Mitochondria/metabolism , Protein Serine-Threonine Kinases
5.
Curr Psychopharmacol ; 102021 Feb 15.
Article in English | MEDLINE | ID: mdl-34707969

ABSTRACT

BACKGROUND: The risk for all addictive drug and non-drug behaviors, especially, in the unmyelinated Prefrontal Cortex (PFC) of adolescents, is important and complex. Many animal and human studies show the epigenetic impact on the developing brain in adolescents, compared to adults. Some reveal an underlying hyperdopaminergia that seems to set our youth up for risky behaviors by inducing high quanta pre-synaptic dopamine release at reward site neurons. In addition, altered reward gene expression in adolescents caused epigenetically by social defeat, like bullying, can continue into adulthood. In contrast, there is also evidence that epigenetic events can elicit adolescent hypodopaminergia. This complexity suggests that neuroscience cannot make a definitive claim that all adolescents carry a hyperdopaminergia trait. OBJECTIVE: The primary issue involves the question of whether there exists a mixed hypo or hyper-dopaminergia in this population. METHOD: Genetic Addiction Risk Score (GARS®) testing was carried out of 24 Caucasians of ages 12-19, derived from families with RDS. RESULTS: We have found that adolescents from this cohort, derived from RDS parents, displayed a high risk for any addictive behavior (a hypodopaminergia), especially, drug-seeking (95%) and alcohol-seeking (64%). CONCLUSION: The adolescents in our study, although more work is required, show a hypodopaminergic trait, derived from a family with Reward Deficiency Syndrome (RDS). Certainly, in future studies, we will analyze GARS in non-RDS Caucasians between the ages of 12-19. The suggestion is first to identify risk alleles with the GARS test and, then, use well-researched precision, pro-dopamine neutraceutical regulation. This "two-hit" approach might prevent tragic fatalities among adolescents, in the face of the American opioid/psychostimulant epidemic.

6.
Mol Neurobiol ; 58(7): 3335-3346, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33683627

ABSTRACT

Millions of Americans experience pain daily. In 2017, opioid overdose claimed 64,000 lives increasing to 84,000 lives in 2020, resulting in a decrease in national life expectancy. Chronic opioid use results in dependency, drug tolerance, neuroadaptation, hyperalgesia, potential addictive behaviors, or Reward Deficiency Syndrome (RDS) caused by a hypodopaminergia. Evaluation of pain clinic patients with the Genetic Addiction Risk Score (GARS) test and the Addiction Severity Index (ASI- Media Version V) revealed that GARS scores equal to or greater than 4 and 7 alleles significantly predicted drug and alcohol severity, respectively. We utilized RT-PCR for SNP genotyping and multiplex PCR/capillary electrophoresis for fragment analysis of the role of eleven alleles in a ten-reward gene panel, reflecting the activity of brain reward circuitry in 121 chronic opioid users. The study consisted of 55 males and 66 females averaging ages 54 and 53 years of age, respectively. The patients included Caucasians, African Americans, Hispanics, and Asians. Inclusion criteria mandated that the Morphine Milligram Equivalent (MME) was 30-600 mg/day (males) and 20 to 180 mg/day (females) for treatment of chronic pain over 12 months. Ninety-six percent carried four or more risk alleles, and 73% carried seven or more risk alleles, suggesting a high predictive risk for opioid and alcohol dependence, respectively. These data indicate that chronic, legally prescribed opioid users attending a pain clinic possess high genetic risk for drug and alcohol addiction. Early identification of genetic risk, using the GARS test upon entry to treatment, may prevent iatrogenic induced opioid dependence.


Subject(s)
Analgesics, Opioid/adverse effects , Chronic Pain/genetics , Genetic Predisposition to Disease/genetics , Inappropriate Prescribing/adverse effects , Opioid-Related Disorders/genetics , Patient Acuity , Adolescent , Adult , Aged , Aged, 80 and over , Analgesics, Opioid/administration & dosage , Behavior, Addictive/diagnosis , Behavior, Addictive/genetics , Chronic Pain/diagnosis , Chronic Pain/drug therapy , Female , Humans , Male , Middle Aged , Opioid-Related Disorders/diagnosis , Pilot Projects , Polymorphism, Single Nucleotide/genetics , Young Adult
7.
Com. Ciências Saúde ; 32(1): 141-146, jan.-mar.2021.
Article in Portuguese, English | LILACS-Express | LILACS | ID: biblio-1357995

ABSTRACT

Objetivo: Descrever a experiência da implantação de uma horta medicinal em uma Unidade de Saúde de um município baiano. Método: relato de experiência da implantação em 3 etapas: reuniões de planejamento, realização de oficinas e a implantação da horta. Resultados e Discussão: As oficinas evidenciaram práticas inseguras relacionadas ao uso de plantas medicinais concomitante com medicamentos alopáticos e substituição do fármaco pelo tratamento com as plantas. Conclusão: a implantação da horta possibilitou a discussão entre a comunidade e os profissionais da unidade sobre o uso de plantas medicinais trazendo a reflexão sobre o resgate de saberes e sentidos das plantas medicinais.


Objective: To describe the experience of implementing a medicinal vegetable garden in a Health Unit in a municipality in Bahia. Method: Experience report of the implementation in 3 stages: planning meetings, holding workshops and setting up the vegetable garden. Results and Discussion: the workshops highlighted unsafe practices related to the use of medicinal plants by users, as well as concomitant use with allopathic drugs and substitution of the drug by treatment with the plants. Conclusion: The implementation of the garden made possible the discussion between the community and the professionals of the unit about the use of medicinal plants bringing the reflection on the rescue of knowledge and senses of medicinal plants.

8.
Curr Psychopharmacol ; 9(1): 7-21, 2020.
Article in English | MEDLINE | ID: mdl-32432025

ABSTRACT

BACKGROUND: The search for an accurate, gene-based test to identify heritable risk factors for Reward Deficiency Syndrome (RDS) was conducted based on hundreds of published studies about the role of dopamine in addictive behaviors, including risk for drug dependence and compulsive/impulsive behavior disorders. The term RDS was first coined by Blum's group in 1995 to identify a group of behaviors with a common neurobiological mechanism associated with a polymorphic allelic propensity for hypodopaminergia. OBJECTIVES: To outline the process used to select risk alleles of reward genes for the Genetic Addiction Risk Score (GARS) test. Consequently, to address the limitations caused by inconsistent results that occur in many case-control behavioral association studies. These limitations are perhaps due to the failure of investigators to adequately screen controls for drug and alcohol use disorder, and any of the many RDS behaviors, including nicotine dependence, obesity, pathological gambling, and internet gaming addiction. METHODS: Review of the literature related to the function of risk alleles of reward genes associated with hypodopaminergia relevant case-control association studies for the selection of alleles to be measured by the Genetic Addiction Risk Score (GARS) test. RESULTS: The prevalence of the DRD2 A1 allele in unscreened controls (33.3%), compared to "Super-Controls" [highly screened RDS controls (3.3%) in proband and family] is used to exemplify a possible solution. CONCLUSION: Unlike one gene-one disease (OGOD), RDS is polygenetic, and very complex. In addition, any RDS-related behaviors must be eliminated from the control group in order to obtain the best possible statistical analysis instead of comparing the phenotype with disease-ridden controls.

9.
J Am Heart Assoc ; 9(7): e014366, 2020 04 07.
Article in English | MEDLINE | ID: mdl-32248761

ABSTRACT

Background Nuclear-to-mitochondrial communication regulating gene expression and mitochondrial function is a critical process following cardiac ischemic injury. In this study, we determined that cyclin C, a component of the Mediator complex, regulates cardiac and mitochondrial function in part by modifying mitochondrial fission. We tested the hypothesis that cyclin C functions as a transcriptional cofactor in the nucleus and a signaling molecule stimulating mitochondrial fission in response to stimuli such as cardiac ischemia. Methods and Results We utilized gain- and loss-of-function mouse models in which the CCNC (cyclin C) gene was constitutively expressed (transgenic, CycC cTg) or deleted (knockout, CycC cKO) in cardiomyocytes. The knockout and transgenic mice exhibited decreased cardiac function and altered mitochondria morphology. The hearts of knockout mice had enlarged mitochondria with increased length and area, whereas mitochondria from the hearts of transgenic mice were significantly smaller, demonstrating a role for cyclin C in regulating mitochondrial dynamics in vivo. Hearts from knockout mice displayed altered gene transcription and metabolic function, suggesting that cyclin C is essential for maintaining normal cardiac function. In vitro and in vivo studies revealed that cyclin C translocates to the cytoplasm, enhancing mitochondria fission following stress. We demonstrated that cyclin C interacts with Cdk1 (cyclin-dependent kinase 1) in vivo following ischemia/reperfusion injury and that, consequently, pretreatment with a Cdk1 inhibitor results in reduced mitochondrial fission. This finding suggests a potential therapeutic target to regulate mitochondrial dynamics in response to stress. Conclusions Our study revealed that cyclin C acts as a nuclear-to-mitochondrial signaling factor that regulates both cardiac hypertrophic gene expression and mitochondrial fission. This finding provides new insights into the regulation of cardiac energy metabolism following acute ischemic injury.


Subject(s)
Cyclin C/metabolism , Energy Metabolism , Mitochondria, Heart/metabolism , Mitochondrial Dynamics , Myocardial Reperfusion Injury/metabolism , Myocytes, Cardiac/metabolism , Animals , CDC2 Protein Kinase/antagonists & inhibitors , CDC2 Protein Kinase/metabolism , Cells, Cultured , Cyclin C/deficiency , Cyclin C/genetics , Disease Models, Animal , Energy Metabolism/drug effects , Humans , Mice, Inbred C57BL , Mice, Knockout , Mitochondria, Heart/drug effects , Mitochondria, Heart/pathology , Mitochondrial Dynamics/drug effects , Myocardial Reperfusion Injury/genetics , Myocardial Reperfusion Injury/pathology , Myocardial Reperfusion Injury/prevention & control , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/pathology , Protein Kinase Inhibitors/pharmacology , Protein Transport , Rats, Wistar , Signal Transduction
10.
Curr Pharm Biotechnol ; 21(6): 528-541, 2020.
Article in English | MEDLINE | ID: mdl-31820688

ABSTRACT

BACKGROUND/AIMS: This case series presents the novel Genetic Addiction Risk Score (GARS®) coupled with a customized pro-dopamine regulator matched to polymorphic reward genes having a hypodopaminergic risk. METHODS: The proband is a female with a history of drug abuse and alcoholism. She experienced a car accident under the influence and voluntarily entered treatment. Following an assessment, she was genotyped using the GARS, and started a neuronutrient with a KB220 base indicated by the identified polymorphisms. She began taking it in April 2018 and continues. RESULTS: She had success in recovery from Substance Use Disorder (SUD) and improvement in socialization, family, economic status, well-being, and attenuation of Major Depression. She tested negative over the first two months in treatment and a recent screening. After approximately two months, her parents also decided to take the GARS and started taking the recommended variants. The proband's father (a binge drinker) and mother (no SUD) both showed improvement in various behavioral issues. Finally, the proband's biological children were also GARS tested, showing a high risk for SUD. CONCLUSION: This three-generation case series represents an example of the impact of genetic information coupled with an appropriate DNA guided "Pro-Dopamine Regulator" in recovery and enhancement of life.


Subject(s)
Behavior, Addictive/genetics , Dopamine/deficiency , Dopamine/genetics , Substance-Related Disorders/genetics , Behavior, Addictive/drug therapy , Behavior, Addictive/psychology , Catecholamines/therapeutic use , Child , Female , Genetic Predisposition to Disease , Humans , Monoamine Oxidase/therapeutic use , Neprilysin/therapeutic use , Nuclear Family , Polymorphism, Genetic , Reward , Substance-Related Disorders/drug therapy , Substance-Related Disorders/psychology
11.
JCI Insight ; 2(15)2017 Aug 03.
Article in English | MEDLINE | ID: mdl-28768905

ABSTRACT

Widespread changes in cardiac gene expression occur during heart failure, yet the mechanisms responsible for coordinating these changes remain poorly understood. The Mediator complex represents a nodal point for modulating transcription by bridging chromatin-bound transcription factors with RNA polymerase II activity; it is reversibly regulated by its cyclin-dependent kinase 8 (Cdk8) kinase submodule. Here, we identified increased Cdk8 protein expression in human failing heart explants and determined the consequence of this increase in cardiac-specific Cdk8-expressing mice. Transgenic Cdk8 overexpression resulted in progressive dilated cardiomyopathy, heart failure, and premature lethality. Prior to functional decline, left ventricular cardiomyocytes were dramatically elongated, with disorganized transverse tubules and dysfunctional calcium handling. RNA sequencing results showed that myofilament gene isoforms not typically expressed in adult cardiomyocytes were enriched, while oxidative phosphorylation and fatty acid biosynthesis genes were downregulated. Interestingly, candidate upstream transcription factor expression levels and MAPK signaling pathways thought to determine cardiomyocyte size remained relatively unaffected, suggesting that Cdk8 functions within a novel growth regulatory pathway. Our findings show that manipulating cardiac gene expression through increased Cdk8 levels is detrimental to the heart by establishing a transcriptional program that induces pathological remodeling and eccentric hypertrophy culminating in heart failure.

12.
Am J Physiol Heart Circ Physiol ; 312(4): H768-H780, 2017 Apr 01.
Article in English | MEDLINE | ID: mdl-28159809

ABSTRACT

The mediator complex, a multisubunit nuclear complex, plays an integral role in regulating gene expression by acting as a bridge between transcription factors and RNA polymerase II. Genetic deletion of mediator subunit 1 (Med1) results in embryonic lethality, due in large part to impaired cardiac development. We first established that Med1 is dynamically expressed in cardiac development and disease, with marked upregulation of Med1 in both human and murine failing hearts. To determine if Med1 deficiency protects against cardiac stress, we generated two cardiac-specific Med1 knockout mouse models in which Med1 is conditionally deleted (Med1cKO mice) or inducibly deleted in adult mice (Med1cKO-MCM mice). In both models, cardiac deletion of Med1 resulted in early lethality accompanied by pronounced changes in cardiac function, including left ventricular dilation, decreased ejection fraction, and pathological structural remodeling. We next defined how Med1 deficiency alters the cardiac transcriptional profile using RNA-sequencing analysis. Med1cKO mice demonstrated significant dysregulation of genes related to cardiac metabolism, in particular genes that are coordinated by the transcription factors Pgc1α, Pparα, and Errα. Consistent with the roles of these transcription factors in regulation of mitochondrial genes, we observed significant alterations in mitochondrial size, mitochondrial gene expression, complex activity, and electron transport chain expression under Med1 deficiency. Taken together, these data identify Med1 as an important regulator of vital cardiac gene expression and maintenance of normal heart function.NEW & NOTEWORTHY Disruption of transcriptional gene expression is a hallmark of dilated cardiomyopathy; however, its etiology is not well understood. Cardiac-specific deletion of the transcriptional coactivator mediator subunit 1 (Med1) results in dilated cardiomyopathy, decreased cardiac function, and lethality. Med1 deletion disrupted cardiac mitochondrial and metabolic gene expression patterns.


Subject(s)
Mediator Complex Subunit 1/genetics , Ventricular Remodeling/genetics , Animals , Echocardiography , Electron Transport Chain Complex Proteins/metabolism , Female , Gene Deletion , Heart/diagnostic imaging , Heart/embryology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Myocardium/enzymology , PPAR gamma/genetics , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics , Pregnancy , Receptors, Estrogen/genetics , Stroke Volume , Transcription, Genetic , Up-Regulation , Ventricular Dysfunction, Left/diagnostic imaging , Ventricular Dysfunction, Left/genetics , Ventricular Dysfunction, Left/physiopathology , ERRalpha Estrogen-Related Receptor
14.
PLoS Genet ; 11(5): e1005231, 2015 May.
Article in English | MEDLINE | ID: mdl-25996830

ABSTRACT

Mutations in the human LMNA gene cause muscular dystrophy by mechanisms that are incompletely understood. The LMNA gene encodes A-type lamins, intermediate filaments that form a network underlying the inner nuclear membrane, providing structural support for the nucleus and organizing the genome. To better understand the pathogenesis caused by mutant lamins, we performed a structural and functional analysis on LMNA missense mutations identified in muscular dystrophy patients. These mutations perturb the tertiary structure of the conserved A-type lamin Ig-fold domain. To identify the effects of these structural perturbations on lamin function, we modeled these mutations in Drosophila Lamin C and expressed the mutant lamins in muscle. We found that the structural perturbations had minimal dominant effects on nuclear stiffness, suggesting that the muscle pathology was not accompanied by major structural disruption of the peripheral nuclear lamina. However, subtle alterations in the lamina network and subnuclear reorganization of lamins remain possible. Affected muscles had cytoplasmic aggregation of lamins and additional nuclear envelope proteins. Transcription profiling revealed upregulation of many Nrf2 target genes. Nrf2 is normally sequestered in the cytoplasm by Keap-1. Under oxidative stress Nrf2 dissociates from Keap-1, translocates into the nucleus, and activates gene expression. Unexpectedly, biochemical analyses revealed high levels of reducing agents, indicative of reductive stress. The accumulation of cytoplasmic lamin aggregates correlated with elevated levels of the autophagy adaptor p62/SQSTM1, which also binds Keap-1, abrogating Nrf2 cytoplasmic sequestration, allowing Nrf2 nuclear translocation and target gene activation. Elevated p62/SQSTM1 and nuclear enrichment of Nrf2 were identified in muscle biopsies from the corresponding muscular dystrophy patients, validating the disease relevance of our Drosophila model. Thus, novel connections were made between mutant lamins and the Nrf2 signaling pathway, suggesting new avenues of therapeutic intervention that include regulation of protein folding and metabolism, as well as maintenance of redox homoeostasis.


Subject(s)
Intracellular Signaling Peptides and Proteins/metabolism , Lamin Type A/genetics , Muscular Dystrophies/genetics , NF-E2-Related Factor 2/metabolism , Signal Transduction , Adaptor Proteins, Signal Transducing/genetics , Adaptor Proteins, Signal Transducing/metabolism , Animals , Cell Nucleus , Drosophila/genetics , Drosophila/metabolism , Gene Expression Profiling , Gene Expression Regulation , Homeostasis , Intracellular Signaling Peptides and Proteins/genetics , Kelch-Like ECH-Associated Protein 1 , Lamin Type A/metabolism , Muscle, Skeletal/metabolism , Mutation , NF-E2-Related Factor 2/genetics , Nuclear Lamina/genetics , Nuclear Lamina/metabolism , Oxidative Stress , Protein Conformation , Protein Folding , Sequestosome-1 Protein
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