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1.
Sci Data ; 9(1): 184, 2022 04 21.
Article in English | MEDLINE | ID: mdl-35449141

ABSTRACT

Understanding the neural basis of human movement in naturalistic scenarios is critical for expanding neuroscience research beyond constrained laboratory paradigms. Here, we describe our Annotated Joints in Long-term Electrocorticography for 12 human participants (AJILE12) dataset, the largest human neurobehavioral dataset that is publicly available; the dataset was recorded opportunistically during passive clinical epilepsy monitoring. AJILE12 includes synchronized intracranial neural recordings and upper body pose trajectories across 55 semi-continuous days of naturalistic movements, along with relevant metadata, including thousands of wrist movement events and annotated behavioral states. Neural recordings are available at 500 Hz from at least 64 electrodes per participant, for a total of 1280 hours. Pose trajectories at 9 upper-body keypoints were estimated from 118 million video frames. To facilitate data exploration and reuse, we have shared AJILE12 on The DANDI Archive in the Neurodata Without Borders (NWB) data standard and developed a browser-based dashboard.


Subject(s)
Electrocorticography , Movement , Humans , Software
3.
J Neurosci ; 36(12): 3623-32, 2016 Mar 23.
Article in English | MEDLINE | ID: mdl-27013690

ABSTRACT

The human motor system is capable of remarkably precise control of movements--consider the skill of professional baseball pitchers or surgeons. This precise control relies upon stable representations of movements in the brain. Here, we investigated the stability of cortical activity at multiple spatial and temporal scales by recording local field potentials (LFPs) and action potentials (multiunit spikes, MSPs) while two monkeys controlled a cursor either with their hand or directly from the brain using a brain-machine interface. LFPs and some MSPs were remarkably stable over time periods ranging from 3 d to over 3 years; overall, LFPs were significantly more stable than spikes. We then assessed whether the stability of all neural activity, or just a subset of activity, was necessary to achieve stable behavior. We showed that projections of neural activity into the subspace relevant to the task (the "task-relevant space") were significantly more stable than were projections into the task-irrelevant (or "task-null") space. This provides cortical evidence in support of the minimum intervention principle, which proposes that optimal feedback control (OFC) allows the brain to tightly control only activity in the task-relevant space while allowing activity in the task-irrelevant space to vary substantially from trial to trial. We found that the brain appears capable of maintaining stable movement representations for extremely long periods of time, particularly so for neural activity in the task-relevant space, which agrees with OFC predictions. SIGNIFICANCE STATEMENT: It is unknown whether cortical signals are stable for more than a few weeks. Here, we demonstrate that motor cortical signals can exhibit high stability over several years. This result is particularly important to brain-machine interfaces because it could enable stable performance with infrequent recalibration. Although we can maintain movement accuracy over time, movement components that are unrelated to the goals of a task (such as elbow position during reaching) often vary from trial to trial. This is consistent with the minimum intervention principle of optimal feedback control. We provide evidence that the motor cortex acts according to this principle: cortical activity is more stable in the task-relevant space and more variable in the task-irrelevant space.


Subject(s)
Biofeedback, Psychology/physiology , Brain-Computer Interfaces , Evoked Potentials, Motor/physiology , Motor Cortex/physiology , Movement/physiology , Psychomotor Performance/physiology , Animals , Female , Haplorhini , Longitudinal Studies , Male , Reproducibility of Results , Sensitivity and Specificity
4.
Thorac Cardiovasc Surg ; 64(1): 36-43, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26474008

ABSTRACT

BACKGROUND: A plethora of valves and valve conduits are available for reconstruction of the right ventricular outflow tract (RVOT) for grown-up congenital heart patients. However, for several reasons, the ideal pulmonary valve substitute still remains the subject of debate. In this study, we investigated the preliminary clinical and echocardiographic results after implantation of the RVOT Elan (Vascutek, Renfrewshire, United Kingdom) conduit in adolescents and adults. MATERIAL AND METHODS: Between October 2012 and December 2014, a total of 27 patients (19 males, mean age: 23.7 ± 22.5; range: 9-74 years) received a RVOT Elan conduit for RVOT reconstruction and were prospectively followed up clinically and echocardiographically. Twenty-five patients had previous cardiac surgery. The median number of prior operations per patient was 2 (range: 1-4). Tetralogy of Fallot was the most common diagnosis (n = 7). RESULTS: At a mean follow-up time of 0.9 ± 0.61 years (100% complete), all patients (27 of 27) were alive and in New York Heart Association Class I. Adverse events defined as valve failure, thrombosis, embolism, bleeding, or endocarditis did not occur. Freedom from reoperation in general was 100%. At 1-year follow-up, median peak pressure gradients (Δ Pmax) across the RVOT Elan conduit were 15 ± 3.2; 15.3 ± 2.1Δ, 16 ± 4.8, and 16.3 ± 5.1 mm Hg for the 19 (n = 3), 21 (n = 3), 23 (n = 6), and 25 mm (n = 15) conduit size, respectively. CONCLUSION: The RVOT Elan conduit revealed excellent preliminary clinical and hemodynamic performances independent from the underlying cardiac pathology with insignificant transvalvular gradients and nonturbulent flow characteristics.


Subject(s)
Bioprosthesis , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis , Heart Defects, Congenital/surgery , Heart Valve Prosthesis Implantation/instrumentation , Heart Valve Prosthesis , Pulmonary Artery/transplantation , Pulmonary Valve/transplantation , Adolescent , Adult , Aged , Blood Vessel Prosthesis Implantation/adverse effects , Child , Female , Heart Defects, Congenital/diagnosis , Heart Defects, Congenital/physiopathology , Heart Valve Prosthesis Implantation/adverse effects , Hemodynamics , Humans , Male , Middle Aged , Postoperative Complications/etiology , Prosthesis Design , Pulmonary Artery/diagnostic imaging , Pulmonary Artery/physiopathology , Pulmonary Valve/diagnostic imaging , Pulmonary Valve/physiopathology , Reoperation , Retrospective Studies , Time Factors , Treatment Outcome , Young Adult
5.
Innovations (Phila) ; 10(4): 282-4, 2015.
Article in English | MEDLINE | ID: mdl-26355691

ABSTRACT

A 23-year-old woman with a history of arterial hypertension presented to our institution complaining of dyspnea and chest pain. Her workup including echocardiography and magnetic resonance imaging revealed an aneurysm of the left atrial appendage. No thrombus was identified in the aneurysm or left atrial appendage, and the patient was in sinus rhythm. She was started on prophylactic anticoagulation, and surgical resection of the aneurysm was recommended as a definitive treatment of this lesion. The surgery was performed using a minimally invasive left-sided thoracoscopy approach. The entire left atrial appendage including the aneurysm was removed at its base using an articulating endoscopic stapler device. On postoperative echocardiography, no residual left atrial appendage tissue was evident. The patient could be taken off oral anticoagulation and left the hospital in good condition.


Subject(s)
Atrial Appendage/surgery , Heart Aneurysm/drug therapy , Heart Aneurysm/surgery , Minimally Invasive Surgical Procedures/methods , Adult , Atrial Appendage/diagnostic imaging , Echocardiography , Endoscopy/methods , Factor Xa Inhibitors/therapeutic use , Female , Follow-Up Studies , Heart Aneurysm/congenital , Heart Aneurysm/diagnostic imaging , Humans , Magnetic Resonance Imaging/methods , Radiography , Rare Diseases , Rivaroxaban/therapeutic use , Thoracoscopy/methods , Treatment Outcome
6.
Interact Cardiovasc Thorac Surg ; 21(1): 114-6, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25820760

ABSTRACT

An anomalous origin of the left circumflex coronary artery that arises as a side branch of the right coronary artery from the right coronary sinus of Valsalva encircling the aortic annulus is usually an incidental finding. However, in patients undergoing aortic valve procedures, its existence can significantly complicate the surgical treatment. We report our operative strategy in patients with an anomalous left circumflex coronary artery, a bicuspid aortic valve morphology and different aortic valve pathologies.


Subject(s)
Aortic Aneurysm/surgery , Aortic Valve Insufficiency/surgery , Aortic Valve Stenosis/surgery , Aortic Valve/abnormalities , Aortic Valve/pathology , Blood Vessel Prosthesis Implantation , Calcinosis/surgery , Coronary Vessel Anomalies/complications , Heart Valve Diseases/surgery , Heart Valve Prosthesis Implantation , Aged , Aged, 80 and over , Aortic Aneurysm/complications , Aortic Aneurysm/diagnosis , Aortic Valve/surgery , Aortic Valve Insufficiency/diagnosis , Aortic Valve Insufficiency/etiology , Aortic Valve Stenosis/diagnosis , Aortic Valve Stenosis/etiology , Aortography/methods , Bicuspid Aortic Valve Disease , Bioprosthesis , Calcinosis/diagnosis , Calcinosis/etiology , Coronary Angiography/methods , Coronary Vessel Anomalies/diagnosis , Female , Heart Valve Diseases/complications , Heart Valve Diseases/diagnosis , Heart Valve Prosthesis , Heart Valve Prosthesis Implantation/instrumentation , Humans , Male , Middle Aged , Prosthesis Design , Risk Factors , Tomography, X-Ray Computed , Treatment Outcome
7.
Diabetes ; 64(1): 36-48, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25071026

ABSTRACT

Numerous studies have characterized the antidiabetic effects of adiponectin, yet the precise cellular mechanisms in skeletal muscle, in particular, changes in autophagy, require further clarification. In the current study, we used a high-fat diet (HFD) to induce obesity and insulin resistance in wild-type (WT) or adiponectin knockout (Ad-KO) mice with and without adiponectin replenishment. Temporal analysis of glucose tolerance and insulin sensitivity using hyperinsulinemic-euglycemic clamp and muscle insulin receptor substrate and Akt phosphorylation demonstrated exaggerated and more rapid HFD-induced insulin resistance in skeletal muscle of Ad-KO mice. Superoxide dismutase activity, the reduced glutathione-to-glutathione disulfide ratio, and lipid peroxidation indicated that HFD-induced oxidative stress was corrected by adiponectin. Gene array analysis implicated several antioxidant enzymes, including Gpxs, Prdx, Sod, and Nox4, in mediating this effect. Adiponectin also attenuated palmitate-induced reactive oxygen species production in cultured myotubes and improved insulin-stimulated glucose uptake in primary muscle cells. Increased LC3-II and decreased p62 expression suggested that HFD induced autophagy in muscle of WT mice; however, these changes were not observed in Ad-KO mice. Replenishing adiponectin in Ad-KO mice increased LC3-II and Beclin1 and decreased p62 protein levels, induced fibroblast growth factor-21 expression, and corrected HFD-induced decreases in LC3, Beclin1, and ULK1 gene expression. In vitro studies examining changes in phospho-ULK1 (Ser555), LC3-II, and lysosomal enzyme activity confirmed that adiponectin directly induced autophagic flux in cultured muscle cells in an AMPK-dependent manner. We overexpressed an inactive mutant of Atg5 to create an autophagy-deficient cell model, and together with pharmacological inhibition of autophagy, demonstrated reduced insulin sensitivity under these conditions. In summary, adiponectin stimulated skeletal muscle autophagy and antioxidant potential to reduce insulin resistance caused by HFD.


Subject(s)
Adiponectin/blood , Autophagy/physiology , Insulin Resistance/physiology , Muscle, Skeletal/metabolism , Oxidative Stress/physiology , Adiponectin/genetics , Animals , Antioxidants/metabolism , Autophagy-Related Protein 5 , Cathepsin B/metabolism , Cell Line , Diet, High-Fat , Glucose Clamp Technique , Glucose Tolerance Test , Green Fluorescent Proteins/genetics , Hyperinsulinism/metabolism , Luminescent Proteins/genetics , Mice, Knockout , Microtubule-Associated Proteins/genetics , Microtubule-Associated Proteins/metabolism , Muscle, Skeletal/cytology , Primary Cell Culture , Superoxide Dismutase/metabolism , Red Fluorescent Protein
8.
BMC Biotechnol ; 14: 2, 2014 Jan 09.
Article in English | MEDLINE | ID: mdl-24405853

ABSTRACT

BACKGROUND: The Rho-associated coiled-coil kinase-2 (ROCK2) is an important signaling transducer in the transmission of extracellular signals effecting organization of the actin cytoskeleton. ROCK2 has been implicated in numerous pathologies and the current focus is on understanding the molecular events that couple ROCK2 activity to biological function. To aid in the search for new ROCK2 substrates, we have developed an analog-sensitive (AS) ROCK2 protein that allows the use of selective ATP analogs that are not efficiently utilized by other protein kinases. RESULTS: The analog sensitive protein, M160A ROCK2, was highly active and could phosphorylate proteins from a cellular homogenate with γ32P-N6 (benzyl)ATP. We show the utility of this approach by identifying a putative ROCK2 substrate, elongation initiation factor-1-α1. We further show that the major site of ROCK2 phosphorylation of EIF1α1 is Thr432. CONCLUSIONS: Our work demonstrates that AS-ROCK2 could be useful in a systematic proteomic approach for identifying novel ROCK2 substrates.


Subject(s)
Adenosine Triphosphate/analogs & derivatives , rho-Associated Kinases/metabolism , Amino Acid Substitution , Eukaryotic Initiation Factor-1/metabolism , HEK293 Cells , Humans , Mutagenesis, Site-Directed , Phosphorylation , Signal Transduction , rho-Associated Kinases/genetics
9.
Rev Endocr Metab Disord ; 15(2): 157-67, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24019064

ABSTRACT

The increased prevalence of obesity has mandated extensive research focused on mechanisms responsible for associated clinical complications. Emerging from the focus on adipose tissue biology as a vitally important adipokine is adiponectin which is now believed to mediate anti-diabetic, anti-atherosclerotic, anti-inflammatory, cardioprotective and cancer modifying actions. Adiponectin mediates these primarily beneficial effects via direct signaling effects and via enhancing insulin sensitivity via crosstalk with insulin signaling pathways. Reduced adiponectin action is detrimental and occurs in obesity via decreased circulating levels of adiponectin action or development of adiponectin resistance. This review will focus on cellular mechanisms of adiponectin action, their crosstalk with insulin signaling and the resultant role of adiponectin in cardiovascular disease, diabetes and cancer and reviews data from in vitro cell based studies through animal models to clinical observations.


Subject(s)
Adiponectin/metabolism , Cardiovascular Diseases/metabolism , Diabetes Mellitus, Type 2/metabolism , Metabolic Syndrome/metabolism , Neoplasms/metabolism , Signal Transduction/physiology , Humans
10.
Thorac Cardiovasc Surg Rep ; 3(1): 16-8, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25798352

ABSTRACT

Neoaortic root dilatation can develop during long-term follow-up after an arterial switch operation (ASO). Although few patients require surgical reintervention, significant valve regurgitation is still an important cause of late morbidity. We report on a 15-year-old boy with significant dilatation of the neoaortic root that was treated with the valve-sparing reimplantation technique. There is only one reported case of valve-preserving surgery late after the ASO. Valve preservation is believed to be superior to valve replacement in patients with aortic regurgitation due to better hemodynamic performance and avoidance of anticoagulation therapy.

11.
Article in English | MEDLINE | ID: mdl-24109685

ABSTRACT

Local field potentials (LFPs) have the potential to provide robust, long-lasting control signals for brain-machine interfaces (BMIs). Moreover, they have been hypothesized to be a stable signal source. Here we assess the long-term stability of LFPs and multi-unit spikes (MSPs) in two monkeys using both LFP-based and MSP-based, biomimetic BMIs to control a computer cursor. The monkeys demonstrated highly accurate performance using both the LFP- and MSP-based BMIs. This performance remained high for 11 and 6 months, respectively, without adapting or retraining. We evaluated the stability of the LFP features and MSPs themselves by building, in each session, linear decoders of the BMI-controlled cursor velocity using single features or single MSPs. We then used these single-feature decoders to decode BMI-controlled cursor velocity in the last session. Many of the LFP features and MSPs showed stably-high correlations with the cursor velocity over the entire study period. This implies that the monkeys were able to maintain a stable mapping between either motor cortical field potentials or multi-spike potentials and BMI-controlled outputs.


Subject(s)
Brain-Computer Interfaces , Action Potentials , Animals , Humans , Macaca mulatta , Motor Cortex/physiology , Signal Processing, Computer-Assisted
12.
J Biol Chem ; 288(39): 28293-302, 2013 Sep 27.
Article in English | MEDLINE | ID: mdl-23963453

ABSTRACT

MEKK2 (MAP/ERK kinase kinase-2) is a serine/threonine kinase that belongs to the MEKK/STE11 family of MAP kinase kinase kinases (MAP(3)Ks). MEKK2 integrates stress and mitogenic signals to the activation of NF-κB, JNK1/2, p38, and ERK5 pathways. We have found that MEKK2 is regulated through a phosphorylation-dependent association with 14-3-3, a group of adapters that modulate dimerization and association between proteins. We found that MEKK2 was phosphorylated at Thr-283, which resulted in decreased activation loop phosphorylation at Ser-519 and consequently reduced activity. Mechanistically, we found that MEKK2 associated with inactive MEKK2 in the absence of 14-3-3 binding, which led to trans-autophosphorylation of Ser-519. Enforced binding with 14-3-3 reduced Ser-519 trans-autophosphorylation. Expression of T283A MEKK2 within a MEKK2(-/-) background enhanced stress-activated c-Jun N-terminal kinase activity while elevating IL-6 expression, but also reduced ERK activation with a corresponding reduced proliferation rate. These results indicate that Thr-283 phosphorylation is an important regulatory mechanism for MEKK2 activation.


Subject(s)
14-3-3 Proteins/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Kinase Kinase 2/metabolism , Animals , Binding Sites , Cell Proliferation , Dimerization , Fibroblasts/metabolism , Gene Expression Regulation, Enzymologic , MAP Kinase Signaling System , Mice , Phosphorylation , Protein Binding , Threonine/chemistry
13.
J Neural Eng ; 10(5): 056005, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23918061

ABSTRACT

OBJECTIVE: Brain machine interfaces (BMIs) have the potential to restore movement to people with paralysis. However, a clinically-viable BMI must enable consistently accurate control over time spans ranging from years to decades, which has not yet been demonstrated. Most BMIs that use single-unit spikes as inputs will experience degraded performance over time without frequent decoder re-training. Two other signals, local field potentials (LFPs) and multi-unit spikes (MSPs), may offer greater reliability over long periods and better performance stability than single-unit spikes. Here, we demonstrate that LFPs can be used in a biomimetic BMI to control a computer cursor. APPROACH: We implanted two rhesus macaques with intracortical microelectrodes in primary motor cortex. We recorded LFP and MSP signals from the monkeys while they performed a continuous reaching task, moving a cursor to randomly-placed targets on a computer screen. We then used the LFP and MSP signals to construct biomimetic decoders for control of the cursor. MAIN RESULTS: Both monkeys achieved high-performance, continuous control that remained stable or improved over nearly 12 months using an LFP decoder that was not retrained or adapted. In parallel, the monkeys used MSPs to control a BMI without retraining or adaptation and had similar or better performance, and that predominantly remained stable over more than six months. In contrast to their stable online control, both LFP and MSP signals showed substantial variability when used offline to predict hand movements. SIGNIFICANCE: Our results suggest that the monkeys were able to stabilize the relationship between neural activity and cursor movement during online BMI control, despite variability in the relationship between neural activity and hand movements.


Subject(s)
Brain-Computer Interfaces , Evoked Potentials/physiology , Algorithms , Animals , Data Interpretation, Statistical , Female , Hand/physiology , Macaca mulatta , Male , Microelectrodes , Motor Cortex , Neural Prostheses , Prosthesis Design , Psychomotor Performance/physiology , Reproducibility of Results , Reward
14.
Eur J Cardiothorac Surg ; 44(4): e272-9, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23818571

ABSTRACT

OBJECTIVES: Matrix P® and Matrix P plus® tissue-engineered pulmonary valves (TEPV) were offered as an improvement for pulmonary valve replacement (PVR) because of recellularization by host cells. The high frequency of graft failure gave reason to evaluate the underlying morphological substrate using magnetic resonance imaging (MRI) and histology. METHODS: Between June 2006 and August 2008, 17 Matrix P® and 10 Matrix P plus® TEPVs were implanted in 26 patients with a median age of 12.4 (range: 0.8-38.7, interquartile range: 6.1-18.1) years. The grafts were studied by MRI, and underwent histological examination when explantation was required. RESULTS: Surgical (n = 13) or transcatheter (n = 1) TEPV replacement because of graft failure was needed in 14 cases (52%) 19 (0.5-53) months after implantation. MRI detected significant TEPV stenosis with mild insufficiency (V(max) = 3.7 ± (standard deviation) 0.5 m/s, regurgitant fraction (RGF) = 10 ± 3%) and stenosis with moderate-to-severe insufficiency (V(max) = 3.5 ± 0.8 m/s, RGF = 38 ± 10%) in 6 patients, respectively, and severe insufficiency (RGF = 40%) in 1 patient. In patients with graft failure, MRI showed hyperenhancement and TEPV wall thickening. Histology revealed severe inflammation, increased fibrous tissue and foreign-body reaction against valve leaflets and fascial tissue, while TEPV endothelialization was not detected in any case. CONCLUSIONS: The high frequency of Matrix P® and Matrix P plus® graft failure can be related to inflammation and fibrosis revealed by MRI and histology. Our results do not support the use of these valves for PVR and suggest careful follow-up examinations, including MRI for early detection of graft inflammation and fibrosis.


Subject(s)
Bioprosthesis/adverse effects , Heart Valve Prosthesis Implantation/adverse effects , Heart Valve Prosthesis/adverse effects , Adolescent , Adult , Cardiac Catheterization , Child , Child, Preschool , Echocardiography , Female , Heart Valve Diseases , Heart Valve Prosthesis Implantation/instrumentation , Heart Valve Prosthesis Implantation/methods , Humans , Infant , Kaplan-Meier Estimate , Magnetic Resonance Imaging , Male , Postoperative Complications/etiology , Postoperative Complications/pathology , Prosthesis Failure , Retrospective Studies , Tissue Engineering/methods , Young Adult
15.
Mol Cell Biol ; 33(3): 498-513, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23166294

ABSTRACT

Cell division control protein A7 (CDCA7) is a recently identified target of MYC-dependent transcriptional regulation. We have discovered that CDCA7 associates with MYC and that this association is modulated in a phosphorylation-dependent manner. The prosurvival kinase AKT phosphorylates CDCA7 at threonine 163, promoting binding to 14-3-3, dissociation from MYC, and sequestration to the cytoplasm. Upon serum withdrawal, induction of CDCA7 expression in the presence of MYC sensitized cells to apoptosis, whereas CDCA7 knockdown reduced MYC-dependent apoptosis. The transformation of fibroblasts by MYC was reduced by coexpression of CDCA7, while the non-MYC-interacting protein Δ(156-187)-CDCA7 largely inhibited MYC-induced transformation. These studies provide insight into a new mechanism by which AKT signaling to CDCA7 could alter MYC-dependent growth and transformation, contributing to tumorigenesis.


Subject(s)
Apoptosis , Cell Transformation, Neoplastic/metabolism , Nuclear Proteins/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Proto-Oncogene Proteins c-myc/metabolism , 14-3-3 Proteins/metabolism , Amino Acid Sequence , Animals , Cell Line , Cell Transformation, Neoplastic/genetics , Gene Expression Regulation , Gene Expression Regulation, Neoplastic , HEK293 Cells , Humans , Mice , Molecular Sequence Data , NIH 3T3 Cells , Nuclear Proteins/chemistry , Nuclear Proteins/genetics , Phosphorylation , Rats , Sequence Alignment
17.
Biochem J ; 419(1): 141-8, 2009 Apr 01.
Article in English | MEDLINE | ID: mdl-19099536

ABSTRACT

ROCK (Rho-associated coiled-coil kinase) 2 is a member of the AGC kinase family that plays an essential role downstream of Rho in actin cytoskeleton assembly and contractility. The process of ROCK2 activation is complex and requires suppression of an autoinhibitory mechanism that is facilitated by Rho binding. ROCK2 harbours a C-terminal extension within the kinase domain that contains a hydrophobic cluster of phenylalanine and tyrosine residues surrounding a key threonine residue. In growth-factor-stimulated AGC kinases, the hydrophobic motif is important for the transition of the kinase from inactive to active complex and requires phosphorylation of the conserved serine/threonine residue. Less is understood about the contribution that the hydrophobic motif plays in the activation of ROCK, and the role of the hydrophobic motif threonine at position 405. In the present study, we show that this residue of ROCK is essential for substrate phosphorylation and kinase domain dimerization. However, in contrast with the growth-factor-activated AGC kinases, a phosphomimetic residue at position 405 was inhibitory for ROCK2 activity and dimerization. A soluble hydrophobic motif peptide allosterically activated ROCK2 In vitro, but not the equivalent peptide with Asp(405) substitution. Mechanistically, both ROCK2 activity and dimerization were dependent upon the interaction between Thr(405) of the hydrophobic motif and Asp(39) of the N-terminal extension. The reciprocal exchange of these residues was permissive for kinase activity, but dimerization was lost. These results support the rationale for development of small-molecule inhibitors designed to block ROCK activation by selectively interfering with hydrophobic motif-mediated activation-state transition and dimer formation.


Subject(s)
rho-Associated Kinases/chemistry , rho-Associated Kinases/metabolism , Amino Acid Motifs , Animals , Aspartic Acid/genetics , Aspartic Acid/metabolism , Cell Line , Dimerization , HeLa Cells , Humans , Hydrophobic and Hydrophilic Interactions , Immunoblotting , Immunoprecipitation , Mice , Mutagenesis, Site-Directed , NIH 3T3 Cells , Phosphorylation , Protein Binding , Protein Structure, Tertiary , Threonine/genetics , Threonine/metabolism , rho-Associated Kinases/genetics
18.
Cell Signal ; 20(11): 2038-49, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18718528

ABSTRACT

Protein kinase B (PKB; also known as Akt) is important for mediating survival and proliferation signals. Following activation, PKB shuttles to various compartments of the cell, including the nucleus, where it phosphorylates an array of targets. PKB is phosphorylated at T308 by its activator PDK1. PDK1 is normally excluded from the nucleus via a nuclear exclusion sequence (NES), and our previous work suggested that nuclear exclusion can be attenuated by IGF-1-induced phosphorylation of S396 proximal to the NES. No studies have been done to test the significance of S396 phosphorylation or the impact of nuclear accumulation of PDK1 on PKB activation. To address these questions, we created isogenic embryonic stem cell (ESC) lines expressing various alleles of PDK1 within a PDK1-/- background. Disruption of the NES domain of PDK1 correlated with elevated PKB phosphorylation at both T308 and S473. In contrast, mutation of S396 to alanine reduced PDK1 nuclear localization and reduced PKB phosphorylation and activation. The loss of phosphorylation of PKB by S396A mutation was rescued by forcing nuclear PDK1 or by conversion of S396 to an aspartic acid. The phosphorylation of the PKB substrate FOXO3alpha was reduced in S396A PDK1 ESC. Other known and suspected PKB substrates, including GSK3 and Raf1, were unaffected. This study therefore reveals that S396 plays a role in the activation of PKB leading to the regulated phosphorylation of some PKB substrates including FOXO3alpha.


Subject(s)
Protein Serine-Threonine Kinases/chemistry , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Serine/metabolism , 3-Phosphoinositide-Dependent Protein Kinases , Amino Acid Motifs , Animals , Cell Line , Clone Cells , Embryonic Stem Cells/enzymology , Enzyme Activation , Extracellular Signal-Regulated MAP Kinases/metabolism , Forkhead Box Protein O3 , Forkhead Transcription Factors/metabolism , Glycogen Synthase Kinase 3/metabolism , MAP Kinase Kinase Kinases/metabolism , Mice , Mutation/genetics , Phosphorylation , Protein Structure, Tertiary , Protein Transport , Recombinases/metabolism , Ribosomal Protein S6 Kinases/metabolism , Structure-Activity Relationship , Substrate Specificity
19.
J Biol Chem ; 283(19): 13261-8, 2008 May 09.
Article in English | MEDLINE | ID: mdl-18308725

ABSTRACT

The protein kinase MEKK3 is essential for tumor necrosis factor alpha (TNFalpha)- and lipopolysaccharide-induced activation of nuclear factor kappaB, although the mechanism by which TNF receptor 1 and Toll-like receptors regulate MEKK3 is largely unknown. In this study we have identified MEKK3 Thr(294) as a novel site of phosphorylation that regulates MEKK3 binding with 14-3-3. Phosphorylation of MEKK3 at Thr(294) was observed for both endogenous and ectopically expressed MEKK3. Mutation of Thr(294) to alanine abolished 14-3-3-MEKK3 association and incubation with phosphorylated peptides mimicking Thr(P)(294) competed for 14-3-3 binding. Mutation of Thr(294) did not alter Ser(526) phosphorylation within the activation loop. However, expression of T294A MEKK3 elevated TNFalpha-stimulated NF-kappaB transcriptional activity, suggesting that Thr(294) phosphorylation and 14-3-3 binding negatively regulate MEKK3. Stimulation with TNFalpha or lipopolysaccharide caused a rapid decrease in Thr(294) phosphorylation of endogenous MEKK3 and subsequent loss of 14-3-3 association. Thus, this study identifies a potentially important regulatory step in MEKK3 signaling via dephosphorylation of Thr(294), which reduces 14-3-3 binding correlating with MEKK3 pathway activation.


Subject(s)
14-3-3 Proteins/metabolism , MAP Kinase Kinase Kinase 3/metabolism , NF-kappa B/metabolism , Animals , Antibodies/immunology , Catalysis , Cell Line , Humans , Lipopolysaccharides/pharmacology , MAP Kinase Kinase Kinase 3/genetics , MAP Kinase Kinase Kinase 3/immunology , MAP Kinase Signaling System , Mice , Phosphorylation , Protein Binding , Threonine/genetics , Threonine/metabolism , Tumor Necrosis Factor-alpha/pharmacology
20.
J Biol Chem ; 280(40): 34025-32, 2005 Oct 07.
Article in English | MEDLINE | ID: mdl-16079129

ABSTRACT

Mutations in the PTEN-induced kinase 1 (PINK1) gene have recently been implicated in autosomal recessive early onset Parkinson Disease (1, 2). To investigate the role of PINK1 in neurodegeneration, we designed human and murine neuronal cell lines expressing either wild-type PINK1 or PINK1 bearing a mutation associated with Parkinson Disease. We show that under basal and staurosporine-induced conditions, the number of terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL)-positive cells was lower in wild-type PINK1 expressing SH-SY5Y cells than in mock-transfected cells. This phenotype was due to a PINK1-mediated reduction in cytochrome c release from mitochondria, which prevents subsequent caspase-3 activation. We show that overexpression of wild-type PINK1 strongly reduced both basal and staurosporine-induced caspase 3 activity. Overexpression of wild-type PINK1 also reduced the levels of cleaved caspase-9, caspase-3, caspase-7, and activated poly(ADP-ribose) polymerase under both basal and staurosporine-induced conditions. In contrast, Parkinson disease-related mutations and a kinase-inactive mutation in PINK1 abrogated the protective effect of PINK1. Together, these results suggest that PINK1 reduces the basal neuronal pro-apoptotic activity and protects neurons from staurosporine-induced apoptosis. Loss of this protective function may therefore underlie the degeneration of nigral dopaminergic neurons in patients with PINK1 mutations.


Subject(s)
Apoptosis/genetics , Parkinson Disease/genetics , Protein Kinases/genetics , Protein Kinases/physiology , Aged , Amino Acid Sequence , Caspase 3 , Caspases/metabolism , Cell Culture Techniques , Cell Line , Cytochromes c/metabolism , DNA Mutational Analysis , Fibroblasts , Gene Expression Profiling , Humans , Male , Mitochondria/metabolism , Molecular Sequence Data , Neurons/physiology , Parkinson Disease/pathology , Parkinson Disease/physiopathology , Phenotype , Receptors, Dopamine/physiology , Reverse Transcriptase Polymerase Chain Reaction
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