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Kimball SR, O'Malley JP, Anthony JC, Crozier SJ, Jefferson LS. Assessment of biomarkers of protein anabolism in skeletal muscle during the life span of the rat: sarcopenia despite elevated protein synthesis. Am J Physiol Endocrinol Metab 2004; 287:E772-80. [PMID: 15187001 DOI: 10.1152/ajpendo.00535.2003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Loss of muscle strength is a principal factor in the development of physical frailty, a condition clinically associated with increased risk of bone fractures, impairments in the activities of daily living, and loss of independence in older humans. A primary determinant in the decline in muscle strength that occurs during aging is a loss of muscle mass, which could occur through a reduction in the rate of protein synthesis, an elevation in protein degradation, or a combination of both. In the present study, rates of protein synthesis and the relative expression and function of various biomarkers involved in the initiation of mRNA translation in skeletal muscle were examined at different times throughout the life span of the rat. It was found that between 1 and 6 mo of age, body weight increased fourfold. However, by 6 mo, gastrocnemius protein synthesis and RNA content per gram of muscle were lower than values observed in 1-mo-old rats. Moreover, the relative expression of two proteins involved in the binding of initiator methionyl-tRNA to the 40S ribosomal subunit, eukaryotic initiation factors (eIF)2 and eIF2B, as well as the 70-kDa ribosomal protein S6 kinase, S6K1, was lower at 6 mo compared with 1 mo of age. Muscle mass, protein synthesis, and the aforementioned biomarkers remained unchanged until approximately 21 mo. Between 21 and 24 mo of age, muscle mass decreased precipitously. Surprisingly, during this period protein synthesis, relative RNA content, eIF2B activity, relative eIF2 expression, and S6K1 phosphorylation all increased. The results are consistent with a model wherein protein synthesis is enhanced during aging in a futile attempt to maintain muscle mass.
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Affiliation(s)
- Scot R Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey 17033, USA
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van der Knaap MS, van Berkel CGM, Herms J, van Coster R, Baethmann M, Naidu S, Boltshauser E, Willemsen MAAP, Plecko B, Hoffmann GF, Proud CG, Scheper GC, Pronk JC. eIF2B-related disorders: antenatal onset and involvement of multiple organs. Am J Hum Genet 2003; 73:1199-207. [PMID: 14566705 PMCID: PMC1180499 DOI: 10.1086/379524] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2003] [Accepted: 09/02/2003] [Indexed: 11/03/2022] Open
Abstract
Leukoencephalopathy with vanishing white matter, also called "childhood ataxia with central nervous system hypomyelination," is the first human disease related to mutations in any of the five genes encoding subunits of eukaryotic initiation factor eIF2B or any translation factor at all. eIF2B is essential in all cells of the body for protein synthesis and the regulation of this protein synthesis under different stress conditions. It is surprising that mutations in the eIF2B genes have been reported to lead to abnormalities of the white matter of the brain only, although it has been shown recently that ovarian failure may accompany the leukoencephalopathy. Another surprising observation is that the onset of the disease varies from early childhood to adulthood, with the exception of Cree leukoencephalopathy, a disease related to a particular mutation in one of the eIF2B genes, which invariably has its onset within the first year of life. We analyzed the eIF2B genes of nine patients with an antenatal- or early-infantile-onset encephalopathy and an early demise and found mutations in eight of the patients. In addition to signs of a serious encephalopathy, we found oligohydramnios, intrauterine growth retardation, cataracts, pancreatitis, hepatosplenomegaly, hypoplasia of the kidneys, and ovarian dysgenesis. Until now, no evidence had been found for a genotype-phenotype correlation, but the consistently severe phenotype in affected siblings among our patients and in Cree encephalopathy patients suggests an influence of the genotype on the phenotype.
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Affiliation(s)
- Marjo S van der Knaap
- Department of Child Neurology, Free University Medical Center, Amsterdam, The Netherlands.
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Fogli A, Rodriguez D, Eymard-Pierre E, Bouhour F, Labauge P, Meaney BF, Zeesman S, Kaneski CR, Schiffmann R, Boespflug-Tanguy O. Ovarian failure related to eukaryotic initiation factor 2B mutations. Am J Hum Genet 2003; 72:1544-50. [PMID: 12707859 PMCID: PMC1180314 DOI: 10.1086/375404] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2003] [Accepted: 03/04/2003] [Indexed: 11/03/2022] Open
Abstract
Ovarian failure (OF) at age <40 years occurs in approximately 1% of all women. Other than karyotype abnormalities, very few genes are known to be associated with this ovarian dysfunction. We studied eight patients who presented with premature OF and white-matter abnormalities on magnetic resonance imaging. Neurological signs may be absent or present after OF. In seven patients, we report for the first time mutations in three of the five EIF2B genes (EIF2B2, -4, and -5) that were recently shown to cause childhood ataxia with central nervous system hypomyelination/vanishing white-matter disease leukodystrophy. The correlation we observed between the age at onset of the neurological deterioration and the severity of OF suggests a common pathophysiological pathway.
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Affiliation(s)
- Anne Fogli
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Diana Rodriguez
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Eléonore Eymard-Pierre
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Françoise Bouhour
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Pierre Labauge
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Brandon F. Meaney
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Susan Zeesman
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Christine R. Kaneski
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Raphael Schiffmann
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
| | - Odile Boespflug-Tanguy
- INSERM Unité Mixte de Recherche 384, Faculté de Médecine, Clermont-Ferrand, France; Service de Neuropédiatrie, Hôpital A. Trousseau, INSERM U546, Paris; Neurologie A, Hôpital Pierre Wertheimer, Lyon, France; Département de Neurologie, Centre Hospitalier Universitaire, Nîmes, France; Department of Pediatrics, McMaster University, and Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Canada; and Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda
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