21 results on '"Strub GM"'
Search Results
2. Advanced laryngeal squamous cell carcinoma in an adolescent: A case and treatment considerations.
- Author
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Hunter CJ, Moreno MA, and Strub GM
- Abstract
Pediatric laryngeal SCCa is a rare malignancy in childhood. High index of suspicion is critical to obtain timely tissue sample and diagnosis. Shared decision making is important when choosing treatment modalities for curative management, especially when working with adolescent patients., Competing Interests: All authors of this manuscript declare no conflicts of interest to disclose., (© 2024 The Author(s). Clinical Case Reports published by John Wiley & Sons Ltd.)
- Published
- 2024
- Full Text
- View/download PDF
3. Quantitative plasma proteomic analysis in children after superior cavopulmonary anastomosis with pulmonary arteriovenous malformations.
- Author
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Bolin EH, Mourani PM, Byrum SD, Mackintosh SG, Dossey AM, Angtuaco MJ, Zakaria D, Greiten LE, Strub GM, Zhang H, and Richter GT
- Abstract
Approximately 1000 children are born every year in the United States with one effective cardiac pumping chamber, or single ventricle heart disease. One of the early causes of mortality in this population is pulmonary arteriovenous malformations (PAVMs), which allow blood to bypass gas exchange in the lungs. PAVMs most frequently occur in children after superior cavopulmonary anastomosis (SCPA), a procedure that redirects venous blood from the upper body to the lungs. Because plasma proteins are in part responsible for directing angiogenesis, we hypothesized that differential protein concentrations would be observed in superior caval blood among children after SCPA according to PAVM status. We performed quantitative plasma proteomics from 11 children with PAVMs and in seven children without PAVMs; an additional 11 children with Fontan circulation were included as a reference. Among children with SCPA, there were no significant differences in the plasma proteomes for those with and without PAVMs. When comparing children with Fontan circulation to those with SCPA and PAVMs, 18 proteins exhibited differential expression (10 downregulated and eight upregulated) in superior caval plasma. These results suggest that factors other than, or in addition to, plasma proteins may be responsible for single ventricle patients' susceptibility to PAVMs after SCPA. IMPACT: What is the key message of your article? We did not identify significant differences in plasma proteins when comparing those children with and without pulmonary arteriovenous malformations (PAVMs) after superior cavopulmonary anastomosis (SCPA). What does it add to the existing literature? The etiology of PAVMs in this population is likely due to factors other than, or in addition to, differences in plasma proteins. What is the impact? Further studies are needed to identify causes of PAVMs among children after SCPA., (© 2024. The Author(s), under exclusive licence to the International Pediatric Research Foundation, Inc.)
- Published
- 2024
- Full Text
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4. Massive Subcutaneous Emphysema after Hydrogen Peroxide Irrigation of a Penetrating Facial Injury.
- Author
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Gibson AC, Coleman M, Wilkins HB, Edala T, Nowroozizadeh S, Vandewalle R, and Strub GM
- Subjects
- Humans, Male, Subcutaneous Emphysema etiology, Subcutaneous Emphysema chemically induced, Hydrogen Peroxide adverse effects, Hydrogen Peroxide administration & dosage, Therapeutic Irrigation adverse effects, Therapeutic Irrigation methods, Facial Injuries, Wounds, Penetrating etiology
- Abstract
We present the case of a child impaled in the face by a meat thermometer who subsequently suffered a significant complication due to the administration of hydrogen peroxide to the wound. The soft tissues of the face rapidly expanded and blanched, the child experienced mental status changes, and imaging revealed massive subcutaneous emphysema, pneumomediastinum, and pneumo-orbit. Herein we review the literature on this rare complication and provide photodocumentation in the hopes that other practitioners, patients, and parents avoid administering hydrogen peroxide into or near any penetrating injury. Laryngoscope, 134:2954-2957, 2024., (© 2023 The American Laryngological, Rhinological and Otological Society, Inc.)
- Published
- 2024
- Full Text
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5. Upregulated MicroRNA-21 Drives the Proliferation of Lymphatic Malformation Endothelial Cells by Inhibiting PDCD4.
- Author
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Sun RW, Zhang H, Mehdi SJ, Richter GT, Bowman HH, Sifford J, Smith C, Burnett AK, Layman A, Washam CL, Byrum SD, Bennett JT, Jensen DM, Dmyterko V, Perkins JA, Shawber CJ, Wu JK, and Strub GM
- Subjects
- Apoptosis Regulatory Proteins, Cell Proliferation genetics, Endothelial Cells, MicroRNAs genetics
- Published
- 2023
- Full Text
- View/download PDF
6. Extracranial arteriovenous malformations demonstrate dysregulated TGF-β/BMP signaling and increased circulating TGF-β1.
- Author
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Wei T, Richter GT, Zhang H, Sun RW, Smith CH, and Strub GM
- Subjects
- Endoglin genetics, Growth Differentiation Factor 2, Humans, RNA, Messenger genetics, Transforming Growth Factor beta, Arteriovenous Malformations genetics, Arteriovenous Malformations pathology, Transforming Growth Factor beta1 genetics, Transforming Growth Factor beta1 metabolism
- Abstract
Extracranial arteriovenous malformations (AVMs) are characterized by anomalous arterial-to-venous connections, aberrant angiogenesis, local inflammation and hypoxia, and disorganized histological architecture; however, the precise molecular perturbations leading to this phenotype remain elusive. We hypothesized that extracranial AVM tissue would demonstrate deregulation of the TGF-β/BMP signaling pathway, which may serve as a potential target in the development of molecular-based therapies for AVMs. AVM tissue was harvested during resection from 10 patients with AVMs and compared to control tissue. Blood was collected from 14 AVM patients and 10 patients without AVMs as controls. Expression of TGF-β/BMP pathway components was analyzed using RT-PCR, western blotting, and immunohistochemistry. Circulating levels of TGF-β1 were analyzed by ELISA. Paired t tests were utilized to perform statistical analysis. The mRNA levels of TGF-β1, ALK1, Endoglin (ENG), Smad6, Smad7, and Smad8 were significantly elevated in AVM tissue when compared to controls. Protein levels of TGF-β1 and Smad3 were elevated in AVM tissue while protein levels of BMP-9, ALK1, Smad1, Smad6, and Smad8 were significantly decreased in AVMs. Immunohistochemistry demonstrated increased TGF-β1 in the perivascular cells of AVMs compared to normal controls, and circulating levels of TGF-β1 were significantly higher in AVM patients. Patients with AVMs demonstrate aberrant TGF-β/BMP expression in AVM tissue and blood compared to controls. Targeting aberrantly expressed components of the TGF-β/BMP pathway in extracranial AVMs may be a viable approach in the development of novel molecular therapies, and monitoring circulating TGF-β1 levels may be a useful indicator of treatment success., (© 2022. The Author(s).)
- Published
- 2022
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7. A novel algorithm to reduce bias and improve the quality and diversity of residency interviewees.
- Author
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Lau CO, Johnson AB, Nolder AR, King D, and Strub GM
- Abstract
Objective: Improve the quality and diversity of candidates invited for the Otolaryngology-Head and Neck Surgery residency match by reducing geographical and inter-rater bias with a novel geographic distribution algorithm., Methods: Interview applicants were divided into geographic regions and assigned to reviewers. Each reviewer selected by force-ranking a pre-determined number of applicants to invite for interviews based on the percentage of applications received for each region. Our novel geographic distribution algorithm was then applied to maintain the geographic representation and underrepresented minority status of invited applicants to match the applicant pool., Results: Analysis of previous interview selection methods demonstrated a statistically significant overrepresentation of local applicants invited for interviews. In 2022, 324 domestic applications were received for the otolaryngology match, which were divided into six geographic regions. There was no significant difference in USMLE scores between regions. The implementation of our distribution algorithm during applicant selection eliminated local overrepresentation in the invited pool of applicants and maintained the representation of underrepresented minority applicants. Following the match, reviewers indicated that implementation of the geographic distribution algorithm was simple and improved the quality and diversity of the group of interviewed applicants., Conclusion: Traditional methods of scoring and inviting otolaryngology residency applicants can be confounded by regional and inter-rater biases. Employing a geographic distribution algorithm improves the quality and diversity of invited applicants, eliminates bias, and maintains the representation of underrepresented minority applicants., Competing Interests: All authors confirm that they have no conflict of interest in the submission of this manuscript., (© 2022 The Authors. Laryngoscope Investigative Otolaryngology published by Wiley Periodicals LLC on behalf of The Triological Society.)
- Published
- 2022
- Full Text
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8. Bronchogenic cyst of the posterior neck mimicking lymphatic malformation.
- Author
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Yee A, Navuluri S, Sun R, Lindsey M, Gonzalez-Krellwitz LA, and Strub GM
- Abstract
Bronchogenic cysts are embryologic malformations of the foregut and are rarely found head and neck region. Here we present a case of an upper scapular/lower posterior neck cystic mass which was initially suspicious for lymphatic malformation but confirmed by pathology to be an ectopic bronchogenic cyst., Competing Interests: The authors report no personal or financial conflict of interest., (© 2021 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.)
- Published
- 2022
- Full Text
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9. Detection of Respiratory Pathogens Does Not Predict Risks After Outpatient Adenotonsillectomy.
- Author
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Vickers DM, Reddy A, Akmyradov C, Brown KM, Boyanton BL Jr, Wright HD, Taylor JA, Childress SH, Hartzell LD, Johnson AB, Key JM, Nolder AR, Richter GT, Wineland AM, and Strub GM
- Subjects
- Adolescent, Child, Child, Preschool, Cohort Studies, Double-Blind Method, Female, Humans, Infant, Male, Nasopharynx microbiology, Prospective Studies, Risk, Risk Factors, Adenoidectomy, Air Microbiology, Ambulatory Surgical Procedures, Respiratory Tract Infections microbiology, Surgical Wound Infection microbiology, Tonsillectomy
- Abstract
Objectives/hypothesis: To determine whether the presence of detectable upper respiratory infections (URIs) at the time of adenoidectomy/adenotonsillectomy is associated with increased morbidity, complications, and unexpected admissions., Study Design: Prospective double-blinded cohort., Methods: In this prospective cohort study, nasopharyngeal swabs were obtained intraoperatively from 164 pediatric patients undergoing outpatient adenoidectomy/tonsillectomy with or without pressure equalization tubes (PETs) and were analyzed with PCR for the presence of 22 known URIs, including SARS-CoV-2. Surgeons and families were blinded to the results. At the conclusion of the study, rates of detectable infection were determined and intraoperative and postoperative events (unexpected admissions, length of PACU stay, rates of laryngospasm/bronchospasm, oxygen desaturation, bradycardia, and postoperative presentation to an emergency department) were compared between infected and uninfected patients., Results: Of the 164 patients (50% male, 50% female, ages 8 mo-18 y), 136 patients (82.9%) tested positive for one or more URI at the time of surgery. Forty one patients (25.0%) tested positive for three or more URIs concurrently, and 11 (6.7%) tested positive for five or more URIs concurrently. There were no significant differences in admission rates, length of PACU stay, rates of laryngospasm/bronchospasm, oxygen desaturation, bradycardia, or postoperative presentation to an emergency department between positive and negative patients. No patients tested positive for SARS-CoV-2., Conclusions: A recent positive URI test does not confer any additional intraoperative or postoperative risk in the setting of outpatient adenoidectomy/tonsillectomy in healthy patients. There is no utility in preoperative URI testing, and delaying surgery due to a recent positive URI test is not warranted in this population., Level of Evidence: 3 Laryngoscope, 131:E2074-E2079, 2021., (© 2021 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)
- Published
- 2021
- Full Text
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10. NOTCH pathway activation in infantile hemangiomas.
- Author
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Zhang H, Wei T, Johnson A, Sun R, Richter G, and Strub GM
- Subjects
- Adrenergic beta-Antagonists therapeutic use, Angiogenesis Inhibitors therapeutic use, Child, Preschool, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Female, Hemangioma genetics, Hemangioma pathology, Hemangioma therapy, Humans, Infant, Infant, Newborn, Ligands, Male, Propranolol therapeutic use, Receptors, Notch genetics, Retrospective Studies, Signal Transduction, Transcription Factors genetics, Transcription Factors metabolism, Cell Proliferation drug effects, Hemangioma metabolism, Neovascularization, Pathologic, Receptors, Notch metabolism
- Abstract
Objective: The objective of this study was to characterize the role of NOTCH signaling cascade activation in the angiogenic drive of infantile hemangioma (IH) tissue., Methods: Both IH tissue and normal skin were collected from 55 surgical patients. Of these, 14 were proliferating hemangiomas, 14 were stationary, 14 were involuted, and 13 had been treated with propranolol. Protein and RNA were extracted from all tissues and subjected to Western blotting and reverse transcription-polymerase chain reaction, respectively, for components of the NOTCH signaling pathway., Results: Compared with normal skin from the same patients, proliferating IHs contained higher levels of messenger RNA and protein for the majority of NOTCH receptors and ligands as well as the downstream coactivator MAML1. Expression of NOTCH receptor ligand messenger RNA and protein was significantly lower in involuting and propranolol-treated IHs., Conclusions: Perturbations in NOTCH signaling follow the natural course and treatment outcome of IHs, suggesting a critical role in their pathogenesis., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2021
- Full Text
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11. MicroRNAs for the pediatric otolaryngologist.
- Author
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Strub GM and Perkins JA
- Subjects
- Child, Gene Expression Regulation, Genetic Markers, Humans, Otolaryngology, Otorhinolaryngologic Diseases diagnosis, Pediatrics, MicroRNAs, Otorhinolaryngologic Diseases genetics
- Abstract
The scope of pediatric otolaryngology is broad and encompasses a wide variety of diseases in which the fundamental phenotype-causing abnormality exists at the level of gene regulation and expression. Development of novel molecular biology instruments to diagnose disease, monitor treatment response, and prevent recurrence will facilitate the delivery of appropriate surgical and adjuvant medical treatments with lower morbidity. MicroRNAs (miRNAs) have emerged as a relatively new class of molecules that directly modulate gene expression and are abnormally expressed in a multitude of disease processes including those within the scope of pediatric otolaryngology. Functionally, miRNAs control multiple cellular functions including angiogenesis, cell proliferation, cell survival, genome stability, and inflammation. These short, non-protein coding RNA molecules are present and stable in tissue, blood, saliva, and urine, making them ideal disease biomarkers. The simple structure of miRNAs and their ability to directly modulate the expression of specific genes lends exciting therapeutic potential to miRNA-based therapies. Here we review the current literature of miRNAs as it relates to diseases within the scope of pediatric otolaryngology, and discuss their potential as diagnostic biomarkers and therapeutic targets., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2018
- Full Text
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12. Endothelial and circulating C19MC microRNAs are biomarkers of infantile hemangioma.
- Author
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Strub GM, Kirsh AL, Whipple ME, Kuo WP, Keller RB, Kapur RP, Majesky MW, and Perkins JA
- Abstract
Infantile hemangioma (IH) is the most common vascular tumor of infancy, and it uniquely regresses in response to oral propranolol. MicroRNAs (miRNAs) have emerged as key regulators of vascular development and are dysregulated in many disease processes, but the role of miRNAs in IH growth has not been investigated. We report expression of C19MC, a primate-specific megacluster of miRNAs expressed in placenta with rare expression in postnatal tissues, in glucose transporter 1-expressing (GLUT-1-expressing) IH endothelial cells and in the plasma of children with IH. Tissue or circulating C19MC miRNAs were not detectable in patients having 9 other types of vascular anomalies or unaffected children, identifying C19MC miRNAs as the first circulating biomarkers of IH. Levels of circulating C19MC miRNAs correlated with IH tumor size and propranolol treatment response, and IH tissue from children treated with propranolol or from children with partially involuted tumors contained lower levels of C19MC miRNAs than untreated, proliferative tumors, implicating C19MC miRNAs as potential drivers of IH pathogenesis. Detection of C19MC miRNAs in the circulation of infants with IH may provide a specific and noninvasive means of IH diagnosis and identification of candidates for propranolol therapy as well as a means to monitor treatment response., Competing Interests: The authors have declared that no conflict of interest exists.
- Published
- 2016
- Full Text
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13. Chronic facial pain and Meckel cave masses as the initial presentation of neurosarcoidosis: a case report.
- Author
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Strub GM, Moore JE, Huang AT, Stevenson AW, and Reiter ER
- Subjects
- Adrenal Cortex Hormones therapeutic use, Adult, Central Nervous System Diseases drug therapy, Cranial Fossa, Posterior, Humans, Magnetic Resonance Imaging, Male, Paresthesia etiology, Sarcoidosis drug therapy, Central Nervous System Diseases complications, Central Nervous System Diseases diagnosis, Chronic Pain etiology, Facial Pain etiology, Sarcoidosis complications, Sarcoidosis diagnosis
- Abstract
Sarcoidosis is a systemic inflammatory disease that can affect virtually every organ system, leading to a wide variety of clinical manifestations. Central nervous system involvement producing neurologic symptoms can occur in patients with sarcoidosis, yet rarely are these symptoms the initial manifestations of the disease. Here we present the case of a 38-year-old man who presented with a history of chronic facial pain, blurred vision, increased lacrimation, and periodontal abscesses. Physical examination revealed no evidence of infection or neoplasm. Magnetic resonance imaging revealed space-occupying lesions in Meckel cave bilaterally, with soft-tissue density extending into the left sphenoid and posterior ethmoid sinuses. Endoscopic biopsy of sinus mucosa demonstrated the presence of noncaseating granulomas and the absence of organisms, findings suggestive of neurosarcoidosis. The diagnosis was further supported by chest radiography, which demonstrated bilateral hilar adenopathy. The patient was treated with corticosteroids, and his facial pain improved markedly. In this article we discuss neurosarcoidosis and its manifestations, diagnosis, and clinical course.
- Published
- 2013
14. The use of negative-pressure therapy in the closure of complex head and neck wounds.
- Author
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Strub GM and Moe KS
- Subjects
- Humans, Wound Healing, Craniocerebral Trauma therapy, Neck Injuries therapy, Negative-Pressure Wound Therapy
- Abstract
The evolution of wound care has seen much technological advancement over many decades. Most recently, negative-pressure therapy, by which a vacuum pressure is applied through a wound bed, has dramatically improved the surgical outcomes of complex wounds. Although initial studies focused on wounds to the abdomen, torso, and extremities, more publications are appearing that demonstrate the efficacy of negative-pressure wound therapy in the head and neck. This article reviews the history and evolution of negative-pressure therapy, highlights the current opinions on its mechanism of action, and summarizes its use in complex head and neck wounds., (Copyright © 2013 Elsevier Inc. All rights reserved.)
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- 2013
- Full Text
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15. Massive transcranial parotid pleomorphic adenoma: recurrence after 30 years.
- Author
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Strub GM, Georgolios A, Graham RS, Powers CN, and Coelho DH
- Abstract
Pleomorphic adenoma, also known as benign mixed tumor, is the most common tumor affecting the parotid gland and can reach massive size; however, intracranial invasion is rare. Recurrence of pleomorphic adenoma after excision is a well-known phenomenon and can present decades after resection of the primary tumor. Here we present the case of a 53-year-old man who presented to our clinic with ear fullness, otalgia, and hearing loss 30 years after undergoing total parotidectomy and external beam radiotherapy for pleomorphic adenoma. Magnetic resonance imaging revealed a massive transcranial tumor invading the mastoid cavity, the dura of the posterior fossa, the fallopian and semicircular canals, the jugular foramen, the lateral infratemporal fossa skull base, the sigmoid and transverse sinuses, and the superior parapharyngeal region. Gross examination and histopathological studies confirmed that the mass was a recurrent pleomorphic adenoma. Here we discuss the features of recurrent pleomorphic adenoma and review the current literature.
- Published
- 2012
- Full Text
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16. Oromandibular reconstruction.
- Author
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Cannon TY, Strub GM, Yawn RJ, and Day TA
- Subjects
- Biocompatible Materials, Bone Transplantation, Dental Implants, Fibula transplantation, Free Tissue Flaps, Humans, Ilium transplantation, Mandible anatomy & histology, Mandible physiology, Plastic Surgery Procedures, Scapula transplantation, Mandible surgery
- Abstract
Mandibular reconstruction is often necessary due to congenital, traumatic, infectious, and following treatment for neoplasms of the region. Mandibular defects following ablative surgery for malignant tumors of the head and neck region impact both form and function and require a multidisciplinary approach to optimize functional and cosmetic outcomes. A variety of options exist for mandibular reconstruction and ranging from primary closure, allografts, and autografts, to locoregional and free tissue transfers. This article will focus upon the reconstructive and rehabilitative options for mandibular defects following treatment for head and neck tumors., (Copyright © 2011 Wiley-Liss, Inc.)
- Published
- 2012
- Full Text
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17. Sphingosine-1-phosphate produced by sphingosine kinase 2 in mitochondria interacts with prohibitin 2 to regulate complex IV assembly and respiration.
- Author
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Strub GM, Paillard M, Liang J, Gomez L, Allegood JC, Hait NC, Maceyka M, Price MM, Chen Q, Simpson DC, Kordula T, Milstien S, Lesnefsky EJ, and Spiegel S
- Subjects
- Amino Acid Sequence, Animals, Cell Line, Electron Transport Complex IV genetics, Humans, Mice, Mice, Inbred C57BL, Mice, Knockout, Myocytes, Cardiac enzymology, Myocytes, Cardiac metabolism, Oxygen Consumption physiology, Phosphotransferases (Alcohol Group Acceptor) genetics, Prohibitins, Repressor Proteins genetics, Sphingosine biosynthesis, Electron Transport Complex IV metabolism, Gene Expression Regulation, Enzymologic physiology, Lysophospholipids biosynthesis, Mitochondria, Heart enzymology, Phosphotransferases (Alcohol Group Acceptor) metabolism, Repressor Proteins metabolism, Sphingosine analogs & derivatives
- Abstract
The potent lipid mediator sphingosine-1-phosphate (S1P) regulates diverse physiological processes by binding to 5 specific GPCRs, although it also has intracellular targets. Here, we demonstrate that S1P, produced in the mitochondria mainly by sphingosine kinase 2 (SphK2), binds with high affinity and specificity to prohibitin 2 (PHB2), a highly conserved protein that regulates mitochondrial assembly and function. In contrast, S1P did not bind to the closely related protein PHB1, which forms large, multimeric complexes with PHB2. In mitochondria from SphK2-null mice, a new aberrant band of cytochrome-c oxidase was detected by blue native PAGE, and interaction between subunit IV of cytochrome-c oxidase and PHB2 was greatly reduced. Moreover, depletion of SphK2 or PHB2 led to a dysfunction in mitochondrial respiration through cytochrome-c oxidase. Our data point to a new action of S1P in mitochondria and suggest that interaction of S1P with homomeric PHB2 is important for cytochrome-c oxidase assembly and mitochondrial respiration.
- Published
- 2011
- Full Text
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18. Sphingosine-1-phosphate is a missing cofactor for the E3 ubiquitin ligase TRAF2.
- Author
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Alvarez SE, Harikumar KB, Hait NC, Allegood J, Strub GM, Kim EY, Maceyka M, Jiang H, Luo C, Kordula T, Milstien S, and Spiegel S
- Subjects
- Animals, Biocatalysis, Cell Line, Enzyme Activation, Humans, I-kappa B Kinase metabolism, I-kappa B Proteins metabolism, Lysine metabolism, Lysophospholipids biosynthesis, Lysophospholipids chemistry, Mice, Models, Molecular, NF-KappaB Inhibitor alpha, NF-kappa B metabolism, Phosphorylation, Phosphotransferases (Alcohol Group Acceptor) genetics, Phosphotransferases (Alcohol Group Acceptor) metabolism, Protein Binding, Protein Structure, Tertiary, Receptor-Interacting Protein Serine-Threonine Kinases metabolism, Sphingosine biosynthesis, Sphingosine chemistry, Sphingosine metabolism, Substrate Specificity, TNF Receptor-Associated Factor 2 chemistry, Tumor Necrosis Factor-alpha pharmacology, Ubiquitin-Conjugating Enzymes metabolism, Ubiquitination drug effects, Lysophospholipids metabolism, Sphingosine analogs & derivatives, TNF Receptor-Associated Factor 2 metabolism, Ubiquitin-Protein Ligases metabolism
- Abstract
Tumour-necrosis factor (TNF) receptor-associated factor 2 (TRAF2) is a key component in NF-kappaB signalling triggered by TNF-alpha. Genetic evidence indicates that TRAF2 is necessary for the polyubiquitination of receptor interacting protein 1 (RIP1) that then serves as a platform for recruitment and stimulation of IkappaB kinase, leading to activation of the transcription factor NF-kappaB. Although TRAF2 is a RING domain ubiquitin ligase, direct evidence that TRAF2 catalyses the ubiquitination of RIP1 is lacking. TRAF2 binds to sphingosine kinase 1 (SphK1), one of the isoenzymes that generates the pro-survival lipid mediator sphingosine-1-phosphate (S1P) inside cells. Here we show that SphK1 and the production of S1P is necessary for lysine-63-linked polyubiquitination of RIP1, phosphorylation of IkappaB kinase and IkappaBalpha, and IkappaBalpha degradation, leading to NF-kappaB activation. These responses were mediated by intracellular S1P independently of its cell surface G-protein-coupled receptors. S1P specifically binds to TRAF2 at the amino-terminal RING domain and stimulates its E3 ligase activity. S1P, but not dihydro-S1P, markedly increased recombinant TRAF2-catalysed lysine-63-linked, but not lysine-48-linked, polyubiquitination of RIP1 in vitro in the presence of the ubiquitin conjugating enzymes (E2) UbcH13 or UbcH5a. Our data show that TRAF2 is a novel intracellular target of S1P, and that S1P is the missing cofactor for TRAF2 E3 ubiquitin ligase activity, indicating a new paradigm for the regulation of lysine-63-linked polyubiquitination. These results also highlight the key role of SphK1 and its product S1P in TNF-alpha signalling and the canonical NF-kappaB activation pathway important in inflammatory, antiapoptotic and immune processes.
- Published
- 2010
- Full Text
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19. Extracellular and intracellular actions of sphingosine-1-phosphate.
- Author
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Strub GM, Maceyka M, Hait NC, Milstien S, and Spiegel S
- Subjects
- Animals, Arabidopsis metabolism, Extracellular Space metabolism, Humans, Intracellular Space metabolism, Mammals metabolism, Phosphotransferases (Alcohol Group Acceptor) metabolism, Receptors, Lysosphingolipid metabolism, Saccharomyces cerevisiae metabolism, Sphingolipids metabolism, Sphingosine metabolism, Lysophospholipids metabolism, Sphingosine analogs & derivatives
- Abstract
Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator with crucial roles in a wide variety of cellular functions across a broad range of organisms. Though a simple molecule in structure, S1P functions are complex. The formation of S1P is catalyzed by one of two sphingosine kinases that have differential cellular distributions as well as both overlapping and opposing functions and which are activated by many different stimuli. S1P can act on a family of G protein-coupled receptors (S1PRs) that are also differentially expressed in different cell types, which influences the cellular responses to S1P. In addition to acting on receptors located on the plasma membrane, S1P can also function inside the cell, independently of S1PRs. It also appears that both the intracellular location and the isotype of sphingosine kinase involved are major determinants of inside-out signaling of S1P in response to many extracellular stimuli. This chapter is focused on the current literature on extracellular and intracellular actions of S1P.
- Published
- 2010
- Full Text
- View/download PDF
20. Regulation of histone acetylation in the nucleus by sphingosine-1-phosphate.
- Author
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Hait NC, Allegood J, Maceyka M, Strub GM, Harikumar KB, Singh SK, Luo C, Marmorstein R, Kordula T, Milstien S, and Spiegel S
- Subjects
- Acetylation, Catalytic Domain, Cell Line, Tumor, Cyclin-Dependent Kinase Inhibitor p21 genetics, Cyclin-Dependent Kinase Inhibitor p21 metabolism, Epigenesis, Genetic, Genes, fos, Histone Deacetylase 1, Histone Deacetylase 2, Histone Deacetylase Inhibitors, Histone Deacetylases metabolism, Humans, Lysine metabolism, Nucleosomes metabolism, Phosphotransferases (Alcohol Group Acceptor) genetics, Phosphotransferases (Alcohol Group Acceptor) metabolism, Promoter Regions, Genetic, RNA Interference, Repressor Proteins antagonists & inhibitors, Repressor Proteins metabolism, Sphingosine metabolism, Tetradecanoylphorbol Acetate pharmacology, Cell Nucleus metabolism, Histones metabolism, Lysophospholipids metabolism, Sphingosine analogs & derivatives
- Abstract
The pleiotropic lipid mediator sphingosine-1-phosphate (S1P) can act intracellularly independently of its cell surface receptors through unknown mechanisms. Sphingosine kinase 2 (SphK2), one of the isoenzymes that generates S1P, was associated with histone H3 and produced S1P that regulated histone acetylation. S1P specifically bound to the histone deacetylases HDAC1 and HDAC2 and inhibited their enzymatic activity, preventing the removal of acetyl groups from lysine residues within histone tails. SphK2 associated with HDAC1 and HDAC2 in repressor complexes and was selectively enriched at the promoters of the genes encoding the cyclin-dependent kinase inhibitor p21 or the transcriptional regulator c-fos, where it enhanced local histone H3 acetylation and transcription. Thus, HDACs are direct intracellular targets of S1P and link nuclear S1P to epigenetic regulation of gene expression.
- Published
- 2009
- Full Text
- View/download PDF
21. Recovery from stress is a function of age and telomere length.
- Author
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Strub GM, Depcrynski A, Elmore LW, and Holt SE
- Subjects
- Cells, Cultured, Fibroblasts cytology, Fibroblasts drug effects, Fibroblasts enzymology, Humans, Metals, Heavy toxicity, Molecular Chaperones metabolism, Telomerase metabolism, Cellular Senescence drug effects, Stress, Physiological drug effects, Telomere metabolism
- Abstract
Cells are constantly exposed to a wide variety of stimuli and must be able to mount appropriate physiological responses in order to maintain proper form and function. Cells from every organism have evolved highly conserved mechanisms to cope with environmental changes, including the widely studied heat shock response (HSR), which is induced by a variety of cellular stresses such as heavy metal ion exposure. It has long been known that as organisms and individual cells age, their ability to appropriately cope with environmental stress is attenuated. Here, we examine the ability of two heavy metal ions (ZnCl(2), SnCl(2)) to induce the HSR in human fibroblasts by assessing the expression of heat shock proteins (Hsp90, Hsp70, and p23) and the ability of the cells to recover over time. We demonstrate that the induction and recovery of chaperone levels is attenuated with age and that cells immortalized with the human telomerase reverse transcriptase component of the telomerase enzyme do not attenuate their HSR as their replicative age increases. Our data suggest that the recovery of normal human cells from an HSR is related in part to age and the cell's overall telomere length.
- Published
- 2008
- Full Text
- View/download PDF
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