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1.
Circ J ; 87(1): 111-119, 2022 12 23.
Article in English | MEDLINE | ID: mdl-36070930

ABSTRACT

BACKGROUND: Idiopathic bradyarrhythmia is considered to be due to pathological degeneration of the cardiac conduction system (CCS) during aging. There appears to have been no comprehensive genetic investigations in patients with idiopathic bradyarrhythmia.Methods and Results: Ten autopsy cases with advanced bradyarrhythmia (6 men and 4 women; age: 70-94 years, 81.5±6.9 years; 5 cases each of sinus node dysfunction [SND] and complete atrioventricular block [CAVB]) were genetically investigated by using whole-exome sequencing. Morphometric analysis of the CCS was performed with sex-, age- and comorbidity-matched control cases. As a result, severe loss of nodal cells and distal atrioventricular conduction system were found in SND and CAVB, respectively. However, the conduction tissue loss was not significant in either the atrioventricular node or the proximal bundle of His in CAVB cases. A total of 13 heterozygous potential variants were found in 3 CAVB and 2 SND cases. Of these 13 variants, 4 were missense in the known progressive cardiac conduction disease-related genes: GATA4 and RYR2. In the remaining 9 variants, 5 were loss-of-function mutation with highly possible pathogenicity. CONCLUSIONS: In addition to degenerative changes of selectively vulnerable areas in the heart during advancing age, the vulnerability of the CCS, which may be associated with "rare variants of small effect," may also be a contributing factor to the degeneration of CCS, leading to "idiopathic" bradyarrhythmia.


Subject(s)
Atrioventricular Block , Bradycardia , Male , Humans , Female , Aged , Aged, 80 and over , Bradycardia/genetics , Autopsy , Heart Conduction System , Atrioventricular Block/genetics , Atrioventricular Node , Sick Sinus Syndrome/genetics
2.
Neuropathol Appl Neurobiol ; 47(6): 891-893, 2021 10.
Article in English | MEDLINE | ID: mdl-33760283

ABSTRACT

We showed the results of pathological and genetic investigation for an autopsy case who was evaluated as longstanding Parkinson's disease (PD) in alive. Neuropathological investigation showed "pure nigropathy" without Lewy and tau pathology, and genetic analyses using next-generation sequencing detected novel TUBA4A nonsence mutation. Subsequent physiological study added to strength the hypothesis that the variant is pathogenic one. Present case showed TUBA4A is not only responsible gene for amyotrophic lateral sclerosis/frontotemporal dementia but also PD associated pure nigropathy. Also we found minimal but significant tau pathology high possibly associated with long-term deep brain stimulation in subthalamic nucleus.


Subject(s)
Brain/pathology , Mutation/genetics , Parkinson Disease/genetics , Tubulin/genetics , Amyotrophic Lateral Sclerosis/diagnosis , Amyotrophic Lateral Sclerosis/genetics , Autopsy/methods , Codon, Nonsense/genetics , Frontotemporal Dementia/diagnosis , Frontotemporal Dementia/genetics , Humans , Parkinson Disease/diagnosis , Parkinson Disease/pathology
3.
PLoS One ; 15(4): e0227393, 2020.
Article in English | MEDLINE | ID: mdl-32236096

ABSTRACT

BACKGROUND: TBX5 is a transcription factor that has an important role in development of heart. TBX5 variants in the region encoding the T-box domain have been shown to cause cardiac defects, such as atrial septal defect or ventricular septal defect, while TBX5 variants have also been identified in a few cardiomyopathy patients and considered causative. We identified a TBX5 variant (c.791G>A, p.Arg264Lys), that is over-represented in cardiomyopathy patients. This variant is located outside of the T-box domain, and its pathogenicity has not been confirmed by functional analyses. OBJECTIVE: To investigate whether the TBX5 R264K is deleterious and could contribute to the pathogenesis of cardiomyopathy. METHODS AND RESULTS: We developed mice expressing Tbx5 R264K. Mice homozygous for this variant displayed compensated dilated cardiomyopathy; mild decreased fractional shortening, dilatation of the left ventricle, left ventricular wall thinning and increased heart weight without major heart structural disorders. There was no difference in activation of the ANF promotor, a transcriptional target of Tbx5, compared to wild-type. However, analysis of RNA isolated from left ventricular samples showed significant increases in the expression of Acta1 in left ventricle with concomitant increases in the protein level of ACTA1. CONCLUSIONS: Mice homozygous for Tbx5 R264K showed compensated dilated cardiomyopathy. Thus, TBX5 R264K may have a significant pathogenic role in some cardiomyopathy patients independently of T-box domain pathway.


Subject(s)
Cardiomyopathy, Dilated/genetics , Heart Ventricles/pathology , Isolated Noncompaction of the Ventricular Myocardium/genetics , T-Box Domain Proteins/genetics , Actins/metabolism , Animals , Cardiomyopathy, Dilated/diagnosis , Cardiomyopathy, Dilated/pathology , Child , Disease Models, Animal , Echocardiography , Female , Gene Knock-In Techniques , Genetic Testing , HEK293 Cells , Heart Ventricles/diagnostic imaging , Heart Ventricles/growth & development , Heterozygote , Humans , Infant , Infant, Newborn , Isolated Noncompaction of the Ventricular Myocardium/diagnosis , Male , Mice , Mice, Transgenic , Mutation, Missense , Polymorphism, Single Nucleotide
4.
Brain Dev ; 42(2): 171-178, 2020 Feb.
Article in English | MEDLINE | ID: mdl-31677916

ABSTRACT

AIM: Dravet syndrome (DS) is characterized by high epilepsy-related premature mortality with a markedly young age at death, however, autopsy report of sudden unexpected death with DS has been fewer than expected. METHODS: We report two autopsy cases with sudden unexpected death from DS. Case 1 was a 13-year-old male who drowned in a bathtub, and Case 2 was a 3-year-old female who died while sleeping. In Case 1, the blood concentration of the anticonvulsant, valproic acid, was below the recommended therapeutic range. Neuropathological investigation and genetic analysis of 402 cardiovascular disease-related and 146 epilepsy-related genes by next generation sequencing were applied. RESULTS: No significant neuronal loss with gliosis was observed in the brain of either patient. Although possible mild malformations of cortical development were found in both, the degree thereof was similar to that of age-matched controls. Genetic analysis identified a novel variant in SCN1A intron 23 (c.4477-3T > C) in Case 1 that falls outside of the minor splicing consensus sequence. In vitro splicing functional assays with minigene constructs revealed that this intronic variant leads to a 2-bp insertion immediately before exon 24 that results in protein truncation. Similarly, a novel de novo missense mutation of unknown significance, SCN1A_Arg187Pro, was identified in Case 2. In both cases, we also identified cardiomyopathy-related variants classified as likely pathogenic; however, the effect of these variants at death was minimal because there was an absence of pathological change indicating inherited cardiomyopathy. CONCLUSION: The present cases emphasize the need for multifaceted examination of DS cases so as to obtain a definitive autopsy diagnosis and to explore the mechanism of sudden unexpected death.


Subject(s)
Epilepsies, Myoclonic/genetics , Epilepsies, Myoclonic/mortality , NAV1.1 Voltage-Gated Sodium Channel/genetics , Adolescent , Autopsy , Child, Preschool , Death, Sudden , Epilepsy , Female , Genetic Testing , High-Throughput Nucleotide Sequencing , Humans , Male , Mutation , NAV1.1 Voltage-Gated Sodium Channel/metabolism
5.
J Clin Med ; 8(4)2019 Apr 05.
Article in English | MEDLINE | ID: mdl-30959811

ABSTRACT

Myocyte disarray of >10% in the heart is broadly accepted as a diagnostic pitfall for hypertrophic cardiomyopathy (HCM) at postmortem. The present study aims to propose an additional diagnostic criterion of HCM. Heart specimens from 1387 serial forensic autopsy cases were examined. Cases with myocyte disarray were extracted and applied to morphometric analysis to determine the amount of myocyte disarray. Comprehensive genetic analysis by using next-generation sequencing was subsequently applied for cases with myocyte disarray. Fifteen cases with myocyte disarray were extracted as candidate cases (1.1%, 11 men and 4 women, aged 48⁻94 years). In terms of the cause of death, only 2 cases were cardiac or possible cardiac death, and the other was non-cardiac death. Six cases showed myocyte disarray of >10% and 3 cases showed myocyte disarray of 5% to 10%. The other 6 cases showed myocyte disarray of <5%. Nine rare variants in 5 HCM-related genes (MYBPC3, MYH7, MYH6, PRKAG2, and CAV3) were found in 8 of 9 cases with myocyte disarray of >5%. The remaining 1 and 6 cases with myocyte disarray of <5% did not have any such variant. Myocyte disarray of >5% with rare variants in related genes might be an appropriate postmortem diagnostic criterion for HCM, in addition to myocyte disarray of 10%.

6.
Mod Pathol ; 32(9): 1281-1290, 2019 09.
Article in English | MEDLINE | ID: mdl-31024045

ABSTRACT

Although relatively uncommon, pathologists may encounter minimal inflammatory foci in the absence of typical structural heart disease; however, the clinicopathological significance of minimal inflammatory foci, including correlation with sudden unexpected death, is unexplored. From 1072 serial autopsy subjects, cases with unexplained minimal inflammatory foci, the extent of which was under 1% of the whole examined ventricle, were extracted to exclude cases with borderline/focal myocarditis resulting from local, systemic infection, or autoimmune mechanisms. Immunohistochemistry and genetic analysis targeting viral genomes and heart disease-related genes using next generation sequencing were performed. We detected 10 cases with unexplained minimal inflammatory foci (five males, five females, aged 15-68 years). The cause and/or manner of death were sudden unexpected death (6 cases, 60%), sudden unexpected death with epilepsy (1 case, 10%), drowning in a hot bath (1 case, 10%), and suicide (2 cases, 20%). In none of these cases was pathogen-derived DNA or RNA detected. In 8 of the 10 cases (80%), 17 possible pathogenic genetic variants causative for arrhythmogenic right ventricular cardiomyopathy or dilated cardiomyopathy; DSP was the most frequently involved gene (three cases with two different variants), followed by LAMA4 and MYBPC3 (two cases, two variants for each gene), LDB3 (two cases, one variant), and the remaining 10 variants occurred in seven cases (DSC2, RYR2, SOS1, SCN5A, SGCD, LPL, PKP2, MYH11, GATA6, and DSG2). All mutations were missense mutations. DSP_Lys1581Glu and DSC2_p.Thr275Met were classified according to American College of Medical Genetics and Genomics consensus statement guidelines as pathogenic or likely pathogenic for arrhythmogenic cardiomyopathy in three patients (30%). The remaining 15 variants were classified as potentially pathogenic variants. Unexplained minimal inflammatory foci may be an early sign of inherited cardiomyopathy, and such cases might already have arrhythmogenic potential that can lead to sudden unexpected death. Detection of minimal inflammatory foci by careful pathological examination may indicate the value of conducting comprehensive genetic analysis, even if significant structural abnormalities are not evident.


Subject(s)
Cardiomyopathies/genetics , Death, Sudden, Cardiac/etiology , Inflammation/pathology , Adolescent , Adult , Aged , Cardiomyopathies/pathology , Female , Genetic Predisposition to Disease , High-Throughput Nucleotide Sequencing , Humans , Male , Middle Aged , Young Adult
7.
Appl Microbiol Biotechnol ; 102(3): 1307-1316, 2018 Feb.
Article in English | MEDLINE | ID: mdl-29238872

ABSTRACT

The enzyme responsible for the enantioselective production of (S)-1,1,1-trifluoro-2-propanol ((S)-TFP) from 1,1,1-trifluoroacetone (TFA) has been identified in Ogataea polymorpha NBRC 0799. We purified two carbonyl reductases, OpCRD-A and OpCRD-B from this strain, and revealed their characteristics. Both enzymes were specific to NADH, but the following characteristics were different: The molecular mass of subunit OpCRD-A was 40 kDa and that of OpCRD-B was 43 kDa. Amino acid sequences of both enzymes were only 21% identical. OpCRD-B contained 4 mol of zinc per mole of enzyme, but OpCRD-A did not. The optimal pH, temperature, pH stability, thermostability, and inhibitor specificity were also remarkably different. With regard to substrate specificity, both enzymes exhibited high reductase activity toward a wide variety of ketones, aldehydes and fluoroketones, and dehydrogenase activity toward 2-propanol and 2-butanol. The reductase activity was much higher than the dehydrogenase activity at acidic pH. OpCRD-A enantioselectively produced (S)-TFP from TFA, but OpCRD-B preferentially produced (R)-TFP. Thus, we concluded that OpCRD-A plays the main role in the production of (S)-TFP by a reaction of O. polymorpha NBRC 0799 cells and that OpCRD-A has great potential for efficient production of (S)-TFP, as it is an S-specific enzyme and does not catalyze the dehydrogenation of (S)-TFP.


Subject(s)
Alcohol Oxidoreductases/metabolism , Fungal Proteins/metabolism , Saccharomycetales/enzymology , 2-Propanol/metabolism , Alcohol Oxidoreductases/isolation & purification , Fungal Proteins/isolation & purification , Hydrogen-Ion Concentration , Ketones/metabolism , Kinetics , Molecular Weight , Oxidation-Reduction , Substrate Specificity , Temperature , Trifluoroacetic Acid/metabolism
8.
J Emerg Med ; 48(5): e111-6, 2015 May.
Article in English | MEDLINE | ID: mdl-25641410

ABSTRACT

BACKGROUND: Spontaneous isolated superior mesenteric artery dissection is a rare disease that may cause bowel ischemia or aneurysm rupture and subsequent death. Thus, the establishment of a correct diagnosis in the early stage is quite important. OBJECTIVE: To describe the presentation of 3 patients diagnosed with spontaneous isolated supramesenteric artery dissection and briefly summarize the diagnostic procedure, treatment, and clinical course. CASE REPORTS: We experienced three cases of isolated mesenteric artery dissection in the past 5 years. A definitive diagnosis was obtained by abdominal spiral computed tomography in two cases and angiography in one case. All patients were provided anticoagulation therapy. CONCLUSION: One patient died of bowel ischemia, 2 were discharged within 21 days without complications, and one was able to discontinue anticoagulation therapy 12 months after discharge. The remaining patient has continued warfarin, making it difficult to determine the end point of anticoagulation.


Subject(s)
Mesenteric Artery, Superior/injuries , Vascular Diseases/diagnostic imaging , Vascular Diseases/drug therapy , Abdominal Pain/etiology , Adult , Anticoagulants/therapeutic use , Heparin/therapeutic use , Humans , Male , Mesenteric Artery, Superior/diagnostic imaging , Mesenteric Ischemia/etiology , Middle Aged , Rupture, Spontaneous/diagnostic imaging , Tomography, Spiral Computed , Vascular Diseases/complications , Warfarin/therapeutic use
9.
J Neurosci ; 33(31): 12586-98, 2013 Jul 31.
Article in English | MEDLINE | ID: mdl-23904596

ABSTRACT

During NMDA receptor-mediated long-term potentiation (LTP), synapses are strengthened by trafficking AMPA receptors to the synapse through a calcium-dependent kinase cascade following activation of NMDA receptors. This process results in a long-lasting increase in synaptic strength that is thought to be a cellular mechanism for learning and memory. Over the past 20 years, many signaling pathways have been shown to be involved in the induction and maintenance of LTP including the MAPK cascade. However, the crucial link between NMDA receptors and the signaling cascades involved in AMPA receptor trafficking during LTP remains elusive. In this study, we aimed to identify and characterize NMDA receptor signaling proteins that link NMDA receptor activation to downstream signaling pathways that lead to trafficking of AMPA receptors. We have identified a novel NMDA receptor interacting signaling protein, AGAP3. AGAP3 contains multiple signaling domains, a GTPase-like domain, a pleckstrin homology domain, and an ArfGAP domain, and exists as a component of the NMDA receptor complex. In addition, we found that AGAP3 regulates NMDA receptor-mediated Ras/ERK and Arf6 signaling pathways during chemically induced LTP in rat primary neuronal cultures. Finally, knocking down AGAP3 expression leads to occlusion of AMPA receptor trafficking during chemically induced LTP. Together, AGAP3 is an essential signaling component of the NMDA receptor complex that links NMDA receptor activation to AMPA receptor trafficking.


Subject(s)
ADP-Ribosylation Factors/metabolism , GTPase-Activating Proteins/metabolism , Long-Term Potentiation/physiology , Neurons/physiology , Receptors, AMPA/metabolism , ADP-Ribosylation Factor 6 , ADP-Ribosylation Factors/genetics , Animals , Cells, Cultured , Cerebral Cortex/cytology , Embryo, Mammalian , Female , GTP Phosphohydrolases/metabolism , GTPase-Activating Proteins/genetics , Hippocampus/cytology , Humans , Long-Term Potentiation/drug effects , MAP Kinase Signaling System/genetics , MAP Kinase Signaling System/physiology , Male , Mutation/genetics , Neurons/cytology , Protein Transport/genetics , RNA, Small Interfering/genetics , Rats , Signal Transduction/physiology , Synapses/metabolism
10.
Article in English | MEDLINE | ID: mdl-22577464

ABSTRACT

Objective. The efficacy of influenza vaccination in patients treated with Japanese Oriental (Kampo) Medicine is unknown. The objectives of this study were to observe the efficacy of influenza vaccination in RA patients treated with Kampo. Methods. Trivalent influenza subunit vaccine was administered to 45 RA patients who had received Kampo. They were divided into 2 groups: RA patients treated without MTX ("without MTX group") and treated with MTX ("with MTX group"). Antibody titers were measured before and 4 weeks after vaccination using hemagglutination inhibition assay. Results. Geometric mean titers (GMTs) of anti-influenza antibodies significantly increased for all influenza strains. Response to the influenza vaccination in RA patients treated with Kampo was not lower than that of healthy subjects and the response in the "with MTX group" had a tendency to be higher than that in RA patients treated with MTX in the previous study. There was no significant difference in the GMT after 4 weeks between the "with MTX group" and the "without MTX group." A decreased efficacy in both seroprotection and seroconversion was not found in the "with MTX group." Conclusion. These observations may open the way for further clinical trials to establish the efficacy for the influenza vaccination in RA patients treated with Kampo.

11.
Integr Med Insights ; 6: 1-5, 2011.
Article in English | MEDLINE | ID: mdl-21614162

ABSTRACT

OBJECTIVE: To describe a patient with erhythema and edema after Radix Astragali was added to a kampo formula. CASE SUMMARY: A 21-year-old male, who was diagnosed as having atopic dermatitis in 1989, demonstrated systemic dry eruptions and consulted our department for treatment with traditional herbal medicine (THM) in 2004. The oral administration of herbal medicine resulted in decreased symptoms as well as a reduction in the serum IgE level. In August 2007, he complained of sweating on the neck and we added Radix Astragali to the previous formula. About 18 hours after he ingested the new formula including Radix Astragali, erhythema appeared with swelling of the bilateral hands and feet. Administration of the formula was discontinued and about 48 hours later, his symptoms had almost disappeared. Astragaloside, which is the main ingredient of Radix Astragali, was negative on lymphocyte transforming test (LTT) and we could not determine the ingredient that induced erhythema. CONCLUSION: We consider that the Radix Astragali induced acute erhythema with swelling based on the clinical course. Acute edematous erythema due to THM is very rare and we discuss allergic reactions to traditional herbs and review the litrature.

12.
Altern Ther Health Med ; 16(1): 46-51, 2010.
Article in English | MEDLINE | ID: mdl-20085177

ABSTRACT

OBJECTIVE: To assess the clinical effectiveness and safety of traditional herbal medicines (THM: Kampo) used in combination with oral methotrexate (MTX) in order to control the disease activity of rheumatoid arthritis (RA) in patients whose disease remains active despite treatment with MTX. METHODS: Patients (n=13; male:female = l:12) with RA who achieved only a suboptimal response to MTX therapy (> or =6 mg/week and > or =6 months) were enrolled in this assessment. All patients were treated with Keishinieppiittokaryojutsubu (KER; decoction) according to the traditional diagnostic system. Every 3 months, joint symptoms were examined, and routine blood analysis and general serological tests including anticyclic citrullinated peptide antibody (aCCP) were performed, and then we calculated the disease activity score of 28 joints (DAS28). RESULTS: One patient withdrew from the study after 4 weeks and discontinued consultations with our department for unknown reasons. Five (41.7%) of the twelve patients were defined as responders, and seven patients (58.3%) were classified as nonresponders based on DAS28-CRP findings. On comparison between responders and nonresponders, there was no significant difference with regard to age or disease duration and the dosages of concomitant prednisolone at baseline. KER responders had lower levels of aCCP at baseline than nonresponders (mean +/- standard deviation: 329.2 +/- 113.9 U/mL vs 623.8 +/- 242.8 U/mL, respectively) (P = .046, Mann-Whitney test). Furthermore, responders to KER showed a significant decrease in the serum levels of aCCP. The annual cost for KER treatment is much less than that for other new drugs. CONCLUSION: In patients whose active RA persists despite treatment with MTX, KER in combination with MTX is safe and well tolerated and provides clinical and economic benefits. Furthermore, pretreatment serum levels of aCCP are a useful predictor of a good response to KER treatment, and a decrease in serum levels of aCCP may be an adjunctive indicator in predicting the efficacy of this kind oftreatment.


Subject(s)
Antirheumatic Agents/administration & dosage , Arthritis, Rheumatoid/drug therapy , Drugs, Chinese Herbal/administration & dosage , Medicine, Kampo , Methotrexate/administration & dosage , Adult , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Therapy, Combination , Female , Humans , Male , Middle Aged , Severity of Illness Index , Treatment Outcome
13.
Integr Med Insights ; 5: 1-6, 2010.
Article in English | MEDLINE | ID: mdl-21614161

ABSTRACT

Traditional herbal (Kampo) medicines have been used since ancient times to treat patients with mental disorders. In the present report, we describe four patients with dysthymia successfully treated with Kampo medicines: Kamiuntanto (KUT). These four patients fulfilled the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for dysthymic disorder with easy fatigability and sleeplessness, but did not fulfill the criteria for major depressive disorder. Treatment with KUT relieved depressive status, fatigue and sleeplessness in these patients. As a result, their QOL (quality of life) was considerably improved. KUT may be useful as an additional or alternative treatment for dysthymia, especially in the field of primary health care.

14.
Methods Enzymol ; 448: 23-40, 2008.
Article in English | MEDLINE | ID: mdl-19111169

ABSTRACT

The stability of all RNA polymerase II transcripts depends on the 5'-terminal cap structure. Removal of the cap is a prerequisite for 5' to 3'-decay and is catalyzed by distinct cellular and viral decapping activities. Over the past decade, several decapping enzymes have been characterized through functional and structural studies. An emerging theme is that function is regulated by protein interactions; however, in vitro assays to dissect the effects on enzyme activity are unavailable. Here we present a kinetic assay to monitor decapping by the heterodimeric yeast Dcp1/Dcp2 complex. Kinetic constants related to RNA binding and the rate of the catalytic step can be determined with recombinant enzyme and cap-radiolabeled RNA substrate, allowing substrate specificity and the role of activating factors to be firmly established.


Subject(s)
Genetic Techniques , RNA Caps/metabolism , RNA Stability , Enzymes/metabolism , Humans , Kinetics , Protein Biosynthesis/genetics , RNA Caps/analysis , RNA Caps/genetics , Substrate Specificity
15.
Int J Clin Oncol ; 13(2): 185-9, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18463968

ABSTRACT

We report a 39-year-old woman with premenopausal breast cancer who developed estrogen-deficiency symptoms associated with chemotherapy-related amenorrhea, and was successfully treated with Nyoshinsan/TJ-67, a Japanese traditional herbal medicine (Kampo). Six other breast cancer survivors with menopausal symptoms were also treated with Nyoshinsan/TJ-67, and five of the six patients showed noticeable improvement without adverse effects. Managing estrogen-deficiency symptoms in breast cancer survivors is still problematic, and Nyoshinsan/TJ-67 may be a useful and safe agent for such symptoms in these patients.


Subject(s)
Antineoplastic Agents/adverse effects , Breast Neoplasms/drug therapy , Estrogens/deficiency , Plant Extracts/therapeutic use , Adult , Chemotherapy, Adjuvant/adverse effects , Female , Herbal Medicine , Humans , Middle Aged , Premenopause
16.
17.
J Mol Biol ; 356(4): 982-92, 2006 Mar 03.
Article in English | MEDLINE | ID: mdl-16405910

ABSTRACT

The cap-binding protein eIF4E is the first in a chain of translation initiation factors that recruit 40S ribosomal subunits to the 5' end of eukaryotic mRNA. During cap-dependent translation, this protein binds to the 5'-terminal m(7)Gppp cap of the mRNA, as well as to the adaptor protein eIF4G. The latter then interacts with small ribosomal subunit-bound proteins, thereby promoting the mRNA recruitment process. Here, we show apo-eIF4E to be a protein that contains extensive unstructured regions, which are induced to fold upon recognition of the cap structure. Binding of eIF4G to apo-eIF4E likewise induces folding of the protein into a state that is similar to, but not identical with, that of cap-bound eIF4E. At the same time, binding of each of the binding partners of eIF4E modulates the kinetics with which it interacts with the other partner. We present structural, kinetic and mutagenesis data that allow us to deduce some of the detailed folding transitions that take place during the eIF4E interactions.


Subject(s)
Eukaryotic Initiation Factor-4E/chemistry , Protein Conformation , Protein Folding , RNA Caps/chemistry , RNA, Messenger , Amino Acid Sequence , Eukaryotic Initiation Factor-4E/genetics , Eukaryotic Initiation Factor-4E/metabolism , Eukaryotic Initiation Factor-4G/chemistry , Eukaryotic Initiation Factor-4G/genetics , Eukaryotic Initiation Factor-4G/metabolism , Models, Molecular , Molecular Sequence Data , Nuclear Magnetic Resonance, Biomolecular , RNA, Messenger/chemistry , RNA, Messenger/metabolism , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Surface Plasmon Resonance
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