1
|
Liu J, Guo ZN, Yan XL, Yang Y, Huang S. Brain Pathogenesis and Potential Therapeutic Strategies in Myotonic Dystrophy Type 1. Front Aging Neurosci 2021; 13:755392. [PMID: 34867280 PMCID: PMC8634727 DOI: 10.3389/fnagi.2021.755392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 10/20/2021] [Indexed: 12/17/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy that affects multiple systems including the muscle and heart. The mutant CTG expansion at the 3'-UTR of the DMPK gene causes the expression of toxic RNA that aggregate as nuclear foci. The foci then interfere with RNA-binding proteins, affecting hundreds of mis-spliced effector genes, leading to aberrant alternative splicing and loss of effector gene product functions, ultimately resulting in systemic disorders. In recent years, increasing clinical, imaging, and pathological evidence have indicated that DM1, though to a lesser extent, could also be recognized as true brain diseases, with more and more researchers dedicating to develop novel therapeutic tools dealing with it. In this review, we summarize the current advances in the pathogenesis and pathology of central nervous system (CNS) deficits in DM1, intervention measures currently being investigated are also highlighted, aiming to promote novel and cutting-edge therapeutic investigations.
Collapse
Affiliation(s)
- Jie Liu
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, The First Hospital of Jilin University, Changchun, China
- China National Comprehensive Stroke Center, Changchun, China
- Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Zhen-Ni Guo
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, The First Hospital of Jilin University, Changchun, China
- China National Comprehensive Stroke Center, Changchun, China
- Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Xiu-Li Yan
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, The First Hospital of Jilin University, Changchun, China
| | - Yi Yang
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, The First Hospital of Jilin University, Changchun, China
- China National Comprehensive Stroke Center, Changchun, China
- Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| | - Shuo Huang
- Department of Neurology, Stroke Center & Clinical Trial and Research Center for Stroke, The First Hospital of Jilin University, Changchun, China
- China National Comprehensive Stroke Center, Changchun, China
- Jilin Provincial Key Laboratory of Cerebrovascular Disease, Changchun, China
| |
Collapse
|
2
|
Abstract
Myotonic dystrophy is a dominantly inherited multisystem disorder that results from increased CTG repeats in the 3' region of the myotonic dystrophy protein kinase gene (DMPK). The mutant DMPK mRNA remains in the nucleus and sequesters RNA-binding proteins, including regulators of mRNA splicing. Myotonic dystrophy is characterized by a highly variable phenotype that includes muscle weakness and myotonia, and the disorder may affect the function of many endocrine glands. DMPK mRNA is expressed in muscle, testis, liver, pituitary, thyroid, and bone; the mutated form leads to disruption of meiosis and an increase in fetal insulin receptor-A relative to adult insulin receptor-B, resulting in adult primary testicular failure and insulin resistance predisposing to diabetes, respectively. Patients with myotonic dystrophy are also at increased risk for hyperlipidemia, nonalcoholic fatty liver disease, erectile dysfunction, benign and malignant thyroid nodules, bone fractures, miscarriage, preterm delivery, and failed labor during delivery. Circulating parathyroid hormone and adrenocorticotropic hormone levels may be elevated, but the mechanisms for these associations are unclear. This review summarizes what is known about endocrine dysfunction in individuals with myotonic dystrophy.
Collapse
Affiliation(s)
- Stephen J Winters
- Division of Endocrinology, Metabolism and Diabetes, University of Louisville, Louisville, KY 40202, USA
| |
Collapse
|
3
|
Nieuwenhuis S, Okkersen K, Widomska J, Blom P, 't Hoen PAC, van Engelen B, Glennon JC. Insulin Signaling as a Key Moderator in Myotonic Dystrophy Type 1. Front Neurol 2019; 10:1229. [PMID: 31849810 PMCID: PMC6901991 DOI: 10.3389/fneur.2019.01229] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/05/2019] [Indexed: 12/15/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic disease characterized by multi-system involvement. Affected organ system includes skeletal muscle, heart, gastro-intestinal system and the brain. In this review, we evaluate the evidence for alterations in insulin signaling and their relation to clinical DM1 features. We start by summarizing the molecular pathophysiology of DM1. Next, an overview of normal insulin signaling physiology is given, and evidence for alterations herein in DM1 is presented. Clinically, evidence for involvement of insulin signaling pathways in DM1 is based on the increased incidence of insulin resistance seen in clinical practice and recent trial evidence of beneficial effects of metformin on muscle function. Indirectly, further support may be derived from certain CNS derived symptoms characteristic of DM1, such as obsessive-compulsive behavior features, for which links with altered insulin signaling has been demonstrated in other diseases. At the basic scientific level, several pathophysiological mechanisms that operate in DM1 may compromise normal insulin signaling physiology. The evidence presented here reflects the importance of insulin signaling in relation to clinical features of DM1 and justifies further basic scientific and clinical, therapeutically oriented research.
Collapse
Affiliation(s)
- Sylvia Nieuwenhuis
- Department of Cognitive Neuroscience, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Kees Okkersen
- Department of Neurology, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Joanna Widomska
- Department of Cognitive Neuroscience, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Paul Blom
- VDL Enabling Technologies Group B.V., Eindhoven, Netherlands
| | - Peter A C 't Hoen
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Baziel van Engelen
- Department of Neurology, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Jeffrey C Glennon
- Department of Cognitive Neuroscience, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands
| |
Collapse
|
4
|
Nakka K, Ghigna C, Gabellini D, Dilworth FJ. Diversification of the muscle proteome through alternative splicing. Skelet Muscle 2018; 8:8. [PMID: 29510724 PMCID: PMC5840707 DOI: 10.1186/s13395-018-0152-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/15/2018] [Indexed: 12/16/2022] Open
Abstract
Background Skeletal muscles express a highly specialized proteome that allows the metabolism of energy sources to mediate myofiber contraction. This muscle-specific proteome is partially derived through the muscle-specific transcription of a subset of genes. Surprisingly, RNA sequencing technologies have also revealed a significant role for muscle-specific alternative splicing in generating protein isoforms that give specialized function to the muscle proteome. Main body In this review, we discuss the current knowledge with respect to the mechanisms that allow pre-mRNA transcripts to undergo muscle-specific alternative splicing while identifying some of the key trans-acting splicing factors essential to the process. The importance of specific splicing events to specialized muscle function is presented along with examples in which dysregulated splicing contributes to myopathies. Though there is now an appreciation that alternative splicing is a major contributor to proteome diversification, the emergence of improved “targeted” proteomic methodologies for detection of specific protein isoforms will soon allow us to better appreciate the extent to which alternative splicing modifies the activity of proteins (and their ability to interact with other proteins) in the skeletal muscle. In addition, we highlight a continued need to better explore the signaling pathways that contribute to the temporal control of trans-acting splicing factor activity to ensure specific protein isoforms are expressed in the proper cellular context. Conclusions An understanding of the signal-dependent and signal-independent events driving muscle-specific alternative splicing has the potential to provide us with novel therapeutic strategies to treat different myopathies. Electronic supplementary material The online version of this article (10.1186/s13395-018-0152-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Kiran Nakka
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada
| | - Claudia Ghigna
- Istituto di Genetica Molecolare-Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
| | - Davide Gabellini
- Unit of Gene Expression and Muscular Dystrophy, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, DIBIT2, 5A3-44, via Olgettina 58, 20132, Milan, Italy.
| | - F Jeffrey Dilworth
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada. .,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada. .,Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, 501 Smyth Rd, Mailbox 511, Ottawa, ON, K1H 8L6, Canada.
| |
Collapse
|
5
|
Renna LV, Bosè F, Iachettini S, Fossati B, Saraceno L, Milani V, Colombo R, Meola G, Cardani R. Receptor and post-receptor abnormalities contribute to insulin resistance in myotonic dystrophy type 1 and type 2 skeletal muscle. PLoS One 2017; 12:e0184987. [PMID: 28915272 PMCID: PMC5600405 DOI: 10.1371/journal.pone.0184987] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 09/04/2017] [Indexed: 12/27/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are autosomal dominant multisystemic disorders caused by expansion of microsatellite repeats. In both forms, the mutant transcripts accumulate in nuclear foci altering the function of alternative splicing regulators which are necessary for the physiological mRNA processing. Missplicing of insulin receptor (IR) gene (INSR) has been associated with insulin resistance, however, it cannot be excluded that post-receptor signalling abnormalities could also contribute to this feature in DM. We have analysed the insulin pathway in skeletal muscle biopsies and in myotube cultures from DM patients to assess whether downstream metabolism might be dysregulated and to better characterize the mechanism inducing insulin resistance. DM skeletal muscle exhibits alterations of basal phosphorylation levels of Akt/PKB, p70S6K, GSK3β and ERK1/2, suggesting that these changes might be accompanied by a lack of further insulin stimulation. Alterations of insulin pathway have been confirmed on control and DM myotubes expressing fetal INSR isoform (INSR-A). The results indicate that insulin action appears to be lower in DM than in control myotubes in terms of protein activation and glucose uptake. Our data indicate that post-receptor signalling abnormalities might contribute to DM insulin resistance regardless the alteration of INSR splicing.
Collapse
Affiliation(s)
- Laura Valentina Renna
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Francesca Bosè
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Sara Iachettini
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Barbara Fossati
- Department of Neurology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Lorenzo Saraceno
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Valentina Milani
- Scientific Directorate, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Roberto Colombo
- Department of Biosciences, University of Milan, Milan, Italy
| | - Giovanni Meola
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy.,Department of Neurology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy.,Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese, Milan, Italy
| |
Collapse
|
6
|
Surgical treatment of obesity in DM1 – a case report and a review of the literature. Neuromuscul Disord 2015; 25:414-7. [DOI: 10.1016/j.nmd.2015.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 01/13/2015] [Accepted: 02/09/2015] [Indexed: 11/22/2022]
|
7
|
Chau A, Kalsotra A. Developmental insights into the pathology of and therapeutic strategies for DM1: Back to the basics. Dev Dyn 2015; 244:377-90. [PMID: 25504326 DOI: 10.1002/dvdy.24240] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/25/2014] [Accepted: 11/27/2014] [Indexed: 12/25/2022] Open
Abstract
Myotonic Dystrophy type 1 (DM1), the most prevalent adult onset muscular dystrophy, is a trinucleotide repeat expansion disease caused by CTG expansion in the 3'-UTR of DMPK gene. This expansion results in the expression of toxic gain-of-function RNA that forms ribonuclear foci and disrupts normal activities of RNA-binding proteins belonging to the MBNL and CELF families. Changes in alternative splicing, translation, localization, and mRNA stability due to sequestration of MBNL proteins and up-regulation of CELF1 are key to DM1 pathology. However, recent discoveries indicate that pathogenic mechanisms of DM1 involves many other factors as well, including repeat associated translation, activation of PKC-dependent signaling pathway, aberrant polyadenylation, and microRNA deregulation. Expression of the toxic repeat RNA culminates in the developmental remodeling of the transcriptome, which produces fetal isoforms of proteins that are unable to fulfill the physiological requirements of adult tissues. This review will describe advances in the understanding of DM1 pathogenesis as well as current therapeutic developments for DM1.
Collapse
Affiliation(s)
- Anthony Chau
- Department of Biochemistry, University of Illinois, Urbana-Champaign, Illinois; Department of Medical Biochemistry, University of Illinois, Urbana-Champaign, Illinois; Institute of Genomic Biology, University of Illinois, Urbana-Champaign, Illinois
| | | |
Collapse
|
8
|
Abstract
Myotonic dystrophy (dystrophia myotonica, DM) is one of the most common lethal monogenic disorders in populations of European descent. DM type 1 was first described over a century ago. More recently, a second form of the disease, DM type 2 was recognized, which results from repeat expansion in a different gene. Both disorders have autosomal dominant inheritance and multisystem features, including myotonic myopathy, cataract, and cardiac conduction disease. This article reviews the clinical presentation and pathophysiology of DM and discusses current management and future potential for developing targeted therapies.
Collapse
Affiliation(s)
- Charles A Thornton
- Department of Neurology, Center for Neural Development and Disease, Center for RNA Biology, University of Rochester Medical Center, Box 645, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| |
Collapse
|
9
|
Echeverria GV, Cooper TA. Muscleblind-like 1 activates insulin receptor exon 11 inclusion by enhancing U2AF65 binding and splicing of the upstream intron. Nucleic Acids Res 2013; 42:1893-903. [PMID: 24185704 PMCID: PMC3919616 DOI: 10.1093/nar/gkt1020] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Alternative splicing regulates developmentally and tissue-specific gene expression programs, disruption of which have been implicated in numerous diseases. Muscleblind-like 1 (MBNL1) regulates splicing transitions, which are disrupted on loss of MBNL1 function in myotonic dystrophy type 1 (DM1). One such event is MBNL1-mediated activation of insulin receptor exon 11 inclusion, which requires an intronic enhancer element downstream of exon 11. The mechanism of MBNL1-mediated activation of exon inclusion is unknown. We developed an in vitro splicing assay, which robustly recapitulates MBNL1-mediated splicing activation of insulin receptor exon 11 and found that MBNL1 activates removal of the intron upstream of exon 11 upon binding its functional response element in the downstream intron. MBNL1 enhances early spliceosome assembly as evidenced by enhanced complex A formation and binding of U2 small nuclear ribonucleoprotein auxiliary factor 65 kDa subunit (U2AF65) on the upstream intron. We demonstrated that neither the 5′ splice site nor exon 11 sequences are required for MBNL1-activated U2AF65 binding. Interestingly, the 5′ splice site is required for MBNL1-mediated activation of upstream intron removal, although MBNL1 has no effect on U1 snRNA recruitment. These results suggest that MBNL1 directly activates binding of U2AF65 to enhance upstream intron removal to ultimately activate alternative exon inclusion.
Collapse
Affiliation(s)
- Gloria V Echeverria
- Integrative Molecular and Biomedical Sciences Program, Baylor College of Medicine, Houston, TX 77030, USA, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA and Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | | |
Collapse
|
10
|
Echeverria GV, Cooper TA. RNA-binding proteins in microsatellite expansion disorders: mediators of RNA toxicity. Brain Res 2012; 1462:100-11. [PMID: 22405728 PMCID: PMC3372679 DOI: 10.1016/j.brainres.2012.02.030] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 12/22/2022]
Abstract
Although protein-mediated toxicity in neurological disease has been extensively characterized, RNA-mediated toxicity is an emerging mechanism of pathogenesis. In microsatellite expansion disorders, expansion of repeated sequences in noncoding regions gives rise to RNA that produces a toxic gain of function, while expansions in coding regions can disrupt protein function as well as produce toxic RNA. The toxic RNA typically aggregates into nuclear foci and contributes to disease pathogenesis. In many cases, toxicity of the RNA is caused by the disrupted functions of RNA-binding proteins. We will discuss evidence for RNA-mediated toxicity in microsatellite expansion disorders. Different microsatellite expansion disorders are linked with alterations in the same as well as disease-specific RNA-binding proteins. Recent studies have shown that microsatellite expansions can encode multiple repeat-containing toxic RNAs through bidirectional transcription and protein species through repeat-associated non-ATG translation. We will discuss approaches that have characterized the toxic contributions of these various factors.
Collapse
Affiliation(s)
- Gloria V. Echeverria
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030
| | - Thomas A. Cooper
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030
| |
Collapse
|
11
|
Zhong K, Lei SF, Yang F, Chen XD, Tan LJ, Zhu XZ, Tian Q, Deng HW. The differences of sarcopenia-related phenotypes: effects of gender and population. Eur Rev Aging Phys Act 2011. [DOI: 10.1007/s11556-011-0082-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Abstract
Sarcopenia is a serious condition especially in the elderly population mainly characterized by the loss of skeletal muscle mass and strength with aging. Extremity skeletal muscle mass index (EMMI) (sum of skeletal muscle mass in arms and legs/height2) is gaining popularity in sarcopenia definition (less than two standard deviations below the mean of a young adult reference group), but little is known about the gender- and population-specific differences of EMMI. This study aimed at investigating the differences of EMMI, arm muscle mass index (AMMI), and leg muscle mass index (LMMI) between gender groups and populations (Chinese vs. Caucasians). The participants included 1,809 Chinese and 362 Caucasians with normal weight aged from 19 to 45 years old. Extremity muscle mass, arm muscle mass, and leg muscle mass were measured by using dual energy x-ray absorptiometry. Independent sample t tests were used to analyze the differences in muscle mass indexes between the studied groups. All the study parameters including EMMIs, AMMIs, and LMMIs were significantly higher (P ≤ 0.0003) in the Caucasian group than in the Chinese group and also higher in the male group than in the female group, and these significant differences (P ≤ 0.0005) remained after adjusting for age by simple regressions. The detected differences of muscle mass indexes between different gender and ethnic groups may provide important implications in their different risk of future sarcopenia.
Collapse
|
12
|
Nie J, Xue B, Sukumaran S, Jusko WJ, DuBois DC, Almon RR. Differential muscle gene expression as a function of disease progression in Goto-Kakizaki diabetic rats. Mol Cell Endocrinol 2011; 338:10-7. [PMID: 21356272 PMCID: PMC3093670 DOI: 10.1016/j.mce.2011.02.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 01/26/2011] [Accepted: 02/17/2011] [Indexed: 11/23/2022]
Abstract
The Goto-Kakizaki (GK) rat, a polygenic non-obese model of type 2 diabetes, is a useful surrogate for study of diabetes-related changes independent of obesity. GK rats and appropriate controls were killed at 4, 8, 12, 16 and 20 weeks post-weaning and differential muscle gene expression along with body and muscle weights, plasma hormones and lipids, and blood cell measurements were carried out. Gene expression analysis identified 204 genes showing 2-fold or greater differences between GK and controls in at least 3 ages. Array results suggested increased oxidative capacity in GK muscles, as well as differential gene expression related to insulin resistance, which was also indicated by HOMA-IR measurements. In addition, potential new biomarkers in muscle gene expression were identified that could be either a cause or consequence of T2DM. Furthermore, we demonstrate here the presence of chronic inflammation evident both systemically and in the musculature, despite the absence of obesity.
Collapse
Affiliation(s)
- Jing Nie
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
| | - Bai Xue
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
| | - Siddharth Sukumaran
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
| | - William J. Jusko
- Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
- New York State Center of Excellence in Bioinformatics and Life Sciences
| | - Debra C. DuBois
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
- Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
| | - Richard R. Almon
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
- Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, N.Y. 14260 USA
- New York State Center of Excellence in Bioinformatics and Life Sciences
| |
Collapse
|
13
|
Xue B, Sukumaran S, Nie J, Jusko WJ, DuBois DC, Almon RR. Adipose tissue deficiency and chronic inflammation in diabetic Goto-Kakizaki rats. PLoS One 2011; 6:e17386. [PMID: 21364767 PMCID: PMC3045458 DOI: 10.1371/journal.pone.0017386] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/02/2011] [Indexed: 12/31/2022] Open
Abstract
Type 2 diabetes (T2DM) is a heterogeneous group of diseases that is progressive and involves multiple tissues. Goto-Kakizaki (GK) rats are a polygenic model with elevated blood glucose, peripheral insulin resistance, a non-obese phenotype, and exhibit many degenerative changes observed in human T2DM. As part of a systems analysis of disease progression in this animal model, this study characterized the contribution of adipose tissue to pathophysiology of the disease. We sacrificed subgroups of GK rats and appropriate controls at 4, 8, 12, 16 and 20 weeks of age and carried out a gene array analysis of white adipose tissue. We expanded our physiological analysis of the animals that accompanied our initial gene array study on the livers from these animals. The expanded analysis included adipose tissue weights, HbA1c, additional hormonal profiles, lipid profiles, differential blood cell counts, and food consumption. HbA1c progressively increased in the GK animals. Altered corticosterone, leptin, and adiponectin profiles were also documented in GK animals. Gene array analysis identified 412 genes that were differentially expressed in adipose tissue of GKs relative to controls. The GK animals exhibited an age-specific failure to accumulate body fat despite their relatively higher calorie consumption which was well supported by the altered expression of genes involved in adipogenesis and lipogenesis in the white adipose tissue of these animals, including Fasn, Acly, Kklf9, and Stat3. Systemic inflammation was reflected by chronically elevated white blood cell counts. Furthermore, chronic inflammation in adipose tissue was evident from the differential expression of genes involved in inflammatory responses and activation of natural immunity, including two interferon regulated genes, Ifit and Iipg, as well as MHC class II genes. This study demonstrates an age specific failure to accumulate adipose tissue in the GK rat and the presence of chronic inflammation in adipose tissue from these animals.
Collapse
Affiliation(s)
- Bai Xue
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Siddharth Sukumaran
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Jing Nie
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - William J. Jusko
- Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
- New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York, United States of America
| | - Debra C. DuBois
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
- Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Richard R. Almon
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
- Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, New York, United States of America
- New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York, United States of America
- * E-mail:
| |
Collapse
|
14
|
Abstract
Myotonic dystrophies (dystrophia myotonica, or DM) are inherited disorders characterized by myotonia and progressive muscle degeneration, which are variably associated with a multisystemic phenotype. To date, two types of myotonic dystrophy, type 1 (DM1) and type 2 (DM2), are known to exist; both are autosomal dominant disorders caused by expansion of an untranslated short tandem repeat DNA sequence (CTG)(n) and (CCTG)(n), respectively. These expanded repeats in DM1 and DM2 show different patterns of repeat-size instability. Phenotypes of DM1 and DM2 are similar but there are some important differences, most conspicuously in the severity of the disease (including the presence or absence of the congenital form), muscles primarily affected (distal versus proximal), involved muscle fiber types (type 1 versus type 2 fibers), and some associated multisystemic phenotypes. The pathogenic mechanism of DM1 and DM2 is thought to be mediated by the mutant RNA transcripts containing expanded CUG and CCUG repeats. Strong evidence supports the hypothesis that sequestration of muscle-blind like (MBNL) proteins by these expanded repeats leads to misregulated splicing of many gene transcripts in corroboration with the raised level of CUG-binding protein 1. However, additional mechanisms, such as changes in the chromatin structure involving CTCN-binding site and gene expression dysregulations, are emerging. Although treatment of DM1 and DM2 is currently limited to supportive therapies, new therapeutic approaches based on pathogenic mechanisms may become feasible in the near future.
Collapse
Affiliation(s)
- Tetsuo Ashizawa
- Department of Neurology, McKnight Brain Institute, The University of Texas Medical Branch, Galveston, TX, USA.
| | | |
Collapse
|
15
|
Ward AJ, Rimer M, Killian JM, Dowling JJ, Cooper TA. CUGBP1 overexpression in mouse skeletal muscle reproduces features of myotonic dystrophy type 1. Hum Mol Genet 2010; 19:3614-22. [PMID: 20603324 DOI: 10.1093/hmg/ddq277] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The neuromuscular disease myotonic dystrophy type I (DM1) affects multiple organ systems with the major symptoms being severe muscle weakness, progressive muscle wasting and myotonia. The causative mutation in DM1 is a CTG repeat expansion in the 3'-untranslated region of the DM protein kinase (DMPK) gene. RNA transcribed from the expanded allele contains the expanded CUG repeats and leads to the nuclear depletion of Muscleblind-like 1 (MBNL1) and to the increased steady-state levels of CUG-binding protein 1 (CUGBP1). The pathogenic effects of MBNL1 depletion have previously been tested by the generation of MBNL1 knockout mice, but the consequence of CUGBP1 overexpression in adult muscle is not known. In a DM1 mouse model expressing RNA containing 960 CUG repeats in skeletal muscle, CUGBP1 up-regulation is temporally correlated with severe muscle wasting. In this study, we generated transgenic mice with doxycycline-inducible and skeletal muscle-specific expression of CUGBP1. Adult mouse skeletal muscle overexpressing CUGBP1 reproduces molecular and physiological defects of DM1 tissue. The results from this study strongly suggest that CUGBP1 has a major role in DM1 skeletal muscle pathogenesis.
Collapse
Affiliation(s)
- Amanda J Ward
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | |
Collapse
|
16
|
Shieh K, Gilchrist JM, Promrat K. Frequency and predictors of nonalcoholic fatty liver disease in myotonic dystrophy. Muscle Nerve 2010; 41:197-201. [PMID: 19813185 DOI: 10.1002/mus.21484] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that is strongly associated with insulin resistance. Myotonic dystrophy (DM1) is the most common form of adult-onset muscular dystrophy, and there is a high frequency of insulin resistance due to insulin receptor mRNA splicing defects in muscle tissue. The frequency and predictors of NAFLD in this population have not been described. Thirty-six patients with DM1 were prospectively assessed for the presence of NAFLD and insulin resistance. NAFLD was defined by abnormal liver chemistry tests with ultrasound or pathologic evidence of steatosis in the absence of other liver disease. Abnormal liver chemistry tests were found in 44% of DM1 patients (mean ALT 73 +/- 21 U/L, AST 53 +/- 15 U/L), and 87% were attributable to NAFLD. Clinical predictors of NAFLD included increased insulin resistance by the homeostasis model assessment (HOMA) method (9.5 vs. 4.0 U, P = 0.03), elevated fasting insulin (40.4 vs. 16.1 microIU/ml, P = 0.03), abdominal obesity (98.6 vs. 90.8 cm, P = 0.03), elevated triglycerides (195.7 vs. 136.8 mg/dl, P = 0.02), and elevated total cholesterol (213.6 vs. 180.6 mg/dl, P = 0.02). NAFLD is very common and should be considered in the management of DM1. It is strongly associated with markers of insulin resistance and features of the metabolic syndrome. These findings support the role of peripheral insulin resistance in the pathogenesis of NAFLD.
Collapse
Affiliation(s)
- Kenneth Shieh
- Division of Gastroenterology and Hepatology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, 110 Lockwood Street, Suite 116, Providence, Rhode Island 02903, USA
| | | | | |
Collapse
|
17
|
Llagostera E, Carmona MC, Vicente M, Escorihuela RM, Kaliman P. High-fat diet induced adiposity and insulin resistance in mice lacking the myotonic dystrophy protein kinase. FEBS Lett 2009; 583:2121-5. [PMID: 19482024 DOI: 10.1016/j.febslet.2009.05.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 05/26/2009] [Accepted: 05/26/2009] [Indexed: 11/18/2022]
Abstract
Myotonic dystrophy 1 (MD1) is caused by a CTG expansion in the 3'-unstranslated region of the myotonic dystrophy protein kinase (DMPK) gene. MD1 patients frequently present insulin resistance and increased visceral adiposity. We examined whether DMPK deficiency is a genetic risk factor for high-fat diet-induced adiposity and insulin resistance using the DMPK knockout mouse model. We found that high-fat fed DMPK knockout mice had significantly increased body weights, hypertrophic adipocytes and whole-body insulin resistance compared with wild-type mice. This nutrient-genome interaction should be considered by physicians given the cardiometabolic risks and sedentary lifestyle associated with MD1 patients.
Collapse
Affiliation(s)
- Esther Llagostera
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | | | | | | | | |
Collapse
|
18
|
Abe H, Mita T, Kudo K, Funayama T, Tokoro M, Kaga H, Ikeda F, Kanazawa A, Hirose T, Kawamori R, Watada H. Dramatic improvement of blood glucose control after pioglitazone treatment in poorly controlled over-weight diabetic patients with myotonic dystrophy. Endocr J 2009; 56:911-3. [PMID: 19506327 DOI: 10.1507/endocrj.k09e-122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Insulin resistance is mainly present in skeletal muscle in non-obese patients with myotonic dystrophy. Thiazolidinediones are reported to reduce insulin resistance in these patients. However, the effects of pioglitazone in overweight patients with myotonic dystrophy and type 2 diabetes mellitus have not been established. Here, we evaluated the effect of pioglitazone in two poorly-controlled over-weight diabetic patients with myotonic dystrophy. Case 1 was a 41- year-old women (BMI 27.8 kg/m(2)) with myotonic dystrophy and type 2 diabetes had been treated with 3 mg/day glimepiride and 500 mg/day metformin, but the treatment failed to achieve good glycemic control (HbA(1C) 11.8 %). Following admission to the hospital, she was treated with low-dose insulin and 30 mg/day pioglitazone. At 10 days after initiation of therapy, glycemic control was improved, serum IL-6 and hs-CRP decreased, and adiponectin level increased rapidly. Case 2 was a 47-year-old women (BMI 29.2 kg/m(2)) with myotonic dystrophy and type 2 diabetes mellitus had been treated with insulin without successful glycemic control (HbA(1C) 10.3 %). After admission, she was treated with 15 mg/day pioglitazone. This improved glycemic control, reduced daily insulin requirement, decreased IL-6 and hs-CRP levels rapidly and increased adiponectin level at 10 days after initiation of therapy. In both cases, pioglitazone rapidly improved glycemic control, enhanced adiponectin production, and reduced inflammatory cytokines. These results suggest that pioglitazone may be suitable for these patients.
Collapse
Affiliation(s)
- Hiroko Abe
- Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Matsumura T, Iwahashi H, Funahashi T, Takahashi MP, Saito T, Yasui K, Saito T, Iyama A, Toyooka K, Fujimura H, Shinno S. A cross-sectional study for glucose intolerance of myotonic dystrophy. J Neurol Sci 2008; 276:60-5. [PMID: 18834994 DOI: 10.1016/j.jns.2008.08.037] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 07/12/2008] [Accepted: 08/26/2008] [Indexed: 01/31/2023]
Abstract
We made a cross-sectional study to analyze glucose intolerance of myotonic dystrophy type 1 (DM1) with several examination including oral glucose tolerance test (OGTT), insulin tolerance test (ITT) and adiponectin. Ninety-five DM1 patients participated in this study. Health examination data from general people were used as controls. In DM1, homeostasis model assessment-insulin resistance (HOMA-IR) was higher than control even in the lowest fasting blood sugar (FBS) stage (<80 mg/dl) and insulin sensitivity assessed by ITT was low regardless of their FBS. Insulinogenic index of DM1 was positively correlated to HOMA-IR. Insulinogenic index and sum of IRI in OGTT were markedly elevated in the lowest FBS stage and declined along with elevation of FBS. Consequently, as many as 13.3% of DM1 patients with 90-110 mg/dl of FBS exhibited DM pattern, while only 1.9% in control. Adiponectin was higher in DM1 than control. Although age correlated with adiponectin in both control and DM1, its impact was stronger in DM1. DM1 predisposes insulin resistance and compensatory hyperinsulinemia exist even in patients with low FBS. We should pay attention to glucose intolerance of DM1 patients earlier than that of the general population. It seemed that 90 mg/dl of FBS is an important index as an indication of careful managements.
Collapse
Affiliation(s)
- Tsuyoshi Matsumura
- Department of Neurology, National Hospital Organization Toneyama National Hospital, Toyonaka, Osaka, Japan.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Role of myotonic dystrophy protein kinase (DMPK) in glucose homeostasis and muscle insulin action. PLoS One 2007; 2:e1134. [PMID: 17987120 PMCID: PMC2043489 DOI: 10.1371/journal.pone.0001134] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 10/14/2007] [Indexed: 11/19/2022] Open
Abstract
Myotonic dystrophy 1 (DM1) is caused by a CTG expansion in the 3′-unstranslated region of the DMPK gene, which encodes a serine/threonine protein kinase. One of the common clinical features of DM1 patients is insulin resistance, which has been associated with a pathogenic effect of the repeat expansions. Here we show that DMPK itself is a positive modulator of insulin action. DMPK-deficient (dmpk−/−) mice exhibit impaired insulin signaling in muscle tissues but not in adipocytes and liver, tissues in which DMPK is not expressed. Dmpk−/− mice display metabolic derangements such as abnormal glucose tolerance, reduced glucose uptake and impaired insulin-dependent GLUT4 trafficking in muscle. Using DMPK mutants, we show that DMPK is required for a correct intracellular trafficking of insulin and IGF-1 receptors, providing a mechanism to explain the molecular and metabolic phenotype of dmpk−/− mice. Taken together, these findings indicate that reduced DMPK expression may directly influence the onset of insulin-resistance in DM1 patients and point to dmpk as a new candidate gene for susceptibility to type 2-diabetes.
Collapse
|
21
|
Abstract
The discovery that expansion of unstable repeats can cause a variety of neurological disorders has changed the landscape of disease-oriented research for several forms of mental retardation, Huntington disease, inherited ataxias, and muscular dystrophy. The dynamic nature of these mutations provided an explanation for the variable phenotype expressivity within a family. Beyond diagnosis and genetic counseling, the benefits from studying these disorders have been noted in both neurobiology and cell biology. Examples include insight about the role of translational control in synaptic plasticity, the role of RNA processing in the integrity of muscle and neuronal function, the importance of Fe-S-containing enzymes for cellular energy, and the dramatic effects of altering protein conformations on neuronal function and survival. It is exciting that within a span of 15 years, pathogenesis studies of this class of disorders are beginning to reveal pathways that are potential therapeutic targets.
Collapse
Affiliation(s)
- Harry T Orr
- Institute of Human Genetics, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | | |
Collapse
|
22
|
Abstract
Several examples have come to light in which mutations in non-protein-coding regions give rise to a deleterious gain-of-function by non-coding RNA. Expression of the toxic RNA is associated with formation of nuclear inclusions and late-onset degenerative changes in brain, heart or skeletal muscle. In the best studied example, myotonic dystrophy, it appears that the main pathogenic effect of the toxic RNA is to sequester binding proteins and compromise the regulation of alternative splicing. This review describes some of the recent advances in understanding the pathophysiology of RNA-dominant diseases.
Collapse
Affiliation(s)
- Robert J Osborne
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | | |
Collapse
|
23
|
Abstract
Myotonic dystrophy type 1 (DM1) is caused by a CTG expansion mutation located in the 3' untranslated portion of the dystrophica myotonin protein kinase gene. The identification and characterization of RNA-binding proteins that interact with expanded CUG repeats and the discovery that a similar transcribed but untranslated CCTG expansion in an intron causes myotonic dystrophy type 2 (DM2) have uncovered a new type of mechanism in which microsatellite expansion mutations cause disease through an RNA gain-of-function mechanism. This review discusses RNA pathogenesis in DM1 and DM2 and evidence that similar mechanisms may play a role in a growing number of dominant noncoding expansion disorders, including fragile X tremor ataxia syndrome (FXTAS), spinocerebellar ataxia type 8 (SCA8), SCA10, SCA12, and Huntington's disease-like 2 (HDL2).
Collapse
Affiliation(s)
- Laura P W Ranum
- Institute of Human Genetics and Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | | |
Collapse
|
24
|
Savkur RS, Philips AV, Cooper TA, Dalton JC, Moseley ML, Ranum LPW, Day JW. Insulin receptor splicing alteration in myotonic dystrophy type 2. Am J Hum Genet 2004; 74:1309-13. [PMID: 15114529 PMCID: PMC1182097 DOI: 10.1086/421528] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Accepted: 04/02/2004] [Indexed: 11/03/2022] Open
Abstract
Myotonic dystrophy (DM) is caused by either an untranslated CTG expansion in the 3' untranslated region of the DMPK gene on chromosome 19 (dystrophia myotonica type 1 [DM1]), or an untranslated CCTG tetranucleotide repeat expansion in intron 1 of the ZNF9 gene on chromosome 3 (dystrophia myotonica type 2 [DM2]). RNA-binding proteins adhere to transcripts of the repeat expansions that accumulate in the nucleus, and a trans-dominant dysregulation of pre-mRNA alternative splicing has been demonstrated for several genes. In muscle from patients with DM1, altered insulin-receptor splicing to the nonmuscle isoform corresponds to the insulin insensitivity and diabetes that are part of the DM phenotype; because of insulin-receptor species differences, this effect is not seen in mouse models of the disease. We now demonstrate that comparable splicing abnormalities occur in DM2 muscle prior to the development of muscle histopathology, thus demonstrating an early pathogenic effect of RNA expansions.
Collapse
Affiliation(s)
- R S Savkur
- Department of Pathology, Baylor University, Houston, TX, USA
| | | | | | | | | | | | | |
Collapse
|
25
|
Savkur RS, Philips AV, Cooper TA. Aberrant regulation of insulin receptor alternative splicing is associated with insulin resistance in myotonic dystrophy. Nat Genet 2001; 29:40-7. [PMID: 11528389 DOI: 10.1038/ng704] [Citation(s) in RCA: 569] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is caused by a CTG trinucleotide expansion in the 3' untranslated region of the DM protein kinase gene. People with DM1 have an unusual form of insulin resistance caused by a defect in skeletal muscle. Here we demonstrate that alternative splicing of the insulin receptor (IR) pre-mRNA is aberrantly regulated in DM1 skeletal muscle tissue, resulting in predominant expression of the lower-signaling nonmuscle isoform (IR-A). IR-A also predominates in DM1 skeletal muscle cultures, which exhibit a decreased metabolic response to insulin relative to cultures from normal controls. Steady-state levels of CUG-BP, a regulator of pre-mRNA splicing proposed to mediate some aspects of DM1 pathogenesis, are increased in DM1 skeletal muscle; overexpression of CUG-BP in normal cells induces a switch to IR-A. The CUG-BP protein mediates this switch through an intronic element located upstream of the alternatively spliced exon 11, and specifically binds within this element in vitro. These results support a model in which increased expression of a splicing regulator contributes to insulin resistance in DM1 by affecting IR alternative splicing.
Collapse
Affiliation(s)
- R S Savkur
- Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, USA
| | | | | |
Collapse
|
26
|
Furling D, Marette A, Puymirat J. Insulin-like growth factor I circumvents defective insulin action in human myotonic dystrophy skeletal muscle cells. Endocrinology 1999; 140:4244-50. [PMID: 10465298 DOI: 10.1210/endo.140.9.7057] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Primary human skeletal muscle cell cultures derived from muscles of a myotonic dystrophy (DM) fetus provided a model in which both resistance to insulin action described in DM patient muscles and the potential ability of insulin-like growth factor I (IGF-I) to circumvent this defect could be investigated. Basal glucose uptake was the same in cultured DM cells as in normal myotubes. In DM cells, a dose of 10 nM insulin produced no stimulatory effect on glucose uptake, and at higher concentrations, stimulation of glucose uptake remained significantly lower than that in normal myotubes. In addition, basal and insulin-mediated protein synthesis were both significantly reduced compared with those in normal cells. In DM myotubes, insulin receptor messenger RNA expression and insulin receptor binding were significantly diminished, whereas the expression of GLUT1 and GLUT4 glucose transporters was not affected. These results indicate that impaired insulin action is retained in DM cultured myotubes. The action of recombinant human IGF-I (rhIGF-I) was evaluated in this cellular model. We showed that rhIGF-I is able to stimulate glucose uptake to a similar extent as in control cells and restore normal protein synthesis level in DM myotubes. Thus, rhIGF-I is able to bypass impaired insulin action in DM myotubes. This provides a solid foundation for the eventual use of rhIGF-I as an effective treatment of muscle weakness and wasting in DM.
Collapse
Affiliation(s)
- D Furling
- Department of Medicine, Laval University Medical Research Center, University Hospital Center of Québec, Canada
| | | | | |
Collapse
|
27
|
Gómez JM, Martínez-Matos JA. Leptin after IGF-I generation test in a patient with hypopituitarism and myotonic dystrophy disease. Pituitary 1999; 1:121-3. [PMID: 11081190 DOI: 10.1023/a:1009984505312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A 54-years-old woman diagnosed of myotonic dystrophy (MyD) with past medical history of massive postpartum haemorrhage at age 28 and panhypopituitarism was studied. BMI and body composition were determined and we determined baseline serum IGF-I, IGFBP3, insulin and leptin levels and after the IGF-I generation test performed after the GH administration of 0.1 U/kg/day s.c each evening for 4 days. As expected the patient had lower baseline IGF-I and IGFBP3 with high insulin and leptin levels. After IGF-I generation test, IGF-I, IGFBP3 and insulin levels increases without changes in body composition and leptin levels. In the current study, high leptin baseline levels may reflect the hyperinsulinism action over the adipose tissue in MyD and the effect of hypopituitarism over leptin regulation. After 4 days of GH administration, we demonstrated the lack of a modulatory role on leptin levels of GH and acute insulin increase, and a direct effect of GH on leptin can be excluded.
Collapse
Affiliation(s)
- J M Gómez
- Endocrinology Service, Universitaria de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain.
| | | |
Collapse
|
28
|
Annane D, Fiorelli M, Mazoyer B, Pappata S, Eymard B, Radvanyi H, Junien C, Fardeau M, Merlet P, Gajdos P, Syrota A, Sansom Y, Duboc D. Impaired cerebral glucose metabolism in myotonic dystrophy: a triplet-size dependent phenomenon. Neuromuscul Disord 1998; 8:39-45. [PMID: 9565989 DOI: 10.1016/s0960-8966(97)00144-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Myotonic dystrophy (DM) is caused by an expansion of a CTG triplet repeat sequence in the 3'-noncoding region of a protein kinase gene, yet the mechanism by which the triplet repeat expansion causes disease remains unknown. Impaired glucose penetration into brain tissues has been described in DM patients and is a phenomenon that remains unexplained. The present study shows that altered brain glucose metabolism is triplet repeat dependent. We studied brain glucose metabolism (CMRGlu, mumol/100 g/min) by the use of positron emission tomography and 18F-fluoro-2-deoxy-D-glucose in 11 ambulatory non-obese DM patients and in 11 age and sex matched healthy subjects. All subjects underwent a glucose tolerance test with plasma insulin determinations. The expansion of CTG triplet repeats was analyzed in patients with the probe cDNA25 after EcoRI digestion. As compared to controls, in DM patients, the CMRGlu was significantly decreased (26.26 +/- 5.05 vs. 33.43 +/- 2.18, mumol/100 g/min, P = 0.004), and after oral glucose loading, plasma insulin levels were significantly higher and plasma glucose levels remained unchanged (respectively, F = 11.21, P = 0.004 and F = 0.20, P = 0.66). Subsequently, the glucose/insulin ratio was significantly lower in DM patients (F = 6.25, P = 0.02). The length of the expansion of the CTG repeats correlated negatively with the CMRGlu (r2 = 0.63, P = 0.003) and positively with the area under the curve for insulin changes over time after oral glucose (r2 = 0.49, P = 0.016). We conclude that, in DM patients, the brain metabolism of glucose is impaired in a repeat dependent manner.
Collapse
Affiliation(s)
- D Annane
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, Commissariat à L'Energie Atomique, Orsay, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Gómez Sáez JM, Fernández Real JM, Fernández Castañer M, Navarro Moreno MA, Martínez Matos JA, Soler Ramón J. Study on growth hormone and insulin secretion in myotonic dystrophy. THE CLINICAL INVESTIGATOR 1994; 72:508-11. [PMID: 7981578 DOI: 10.1007/bf00207479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Growth hormone (GH) levels were measured in 12 patients with myotonic dystrophy (MD; 7 men and 5 women, aged 21-49 years) and 14 volunteers after administration of 100 micrograms GH-releasing hormone (GHRH; 1-29). A 75-g oral glucose tolerance test was carried out to determine glucose, insulin, plasma C-peptide, and urinary C-peptide. The GH level in six MD patients responded normally to GHRH (group I), with a peak of 17.1 +/- 1.46 micrograms/l, compared with controls (27.8 +/- 19.6 micrograms/l, NS), and that in the other six patients responded subnormally, with a peak of 3.15 +/- 1.46 micrograms/l, lower than in controls and in group I patients (P < 0.001). In group I the insulin response to the glucose tolerance test showed hyperinsulinism and was lower than that in group II patients; stimulated C-peptide was also higher in group II than in group I and in controls; urinary C-peptide levels were parallel to those in previous data. In all MD patients there were a negative correlation between absolute values of GH response to GHRH and insulin response to glucose tolerance test (r = -0.79, P < 0.001). Our data suggest that the failure in GH release and peripheral insulin action is due to a generalized defect in cellular membrane function in MD patients.
Collapse
Affiliation(s)
- J M Gómez Sáez
- Endocrine Service, Hormonal Laboratory, Ciutat Sanitària i Universitària de Bellvitge, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
30
|
Rifai Z, Kingston WJ, McCraith B, Moxley RT. Forearm 3-methylhistidine efflux in myotonic dystrophy. Ann Neurol 1993; 34:682-6. [PMID: 8239562 DOI: 10.1002/ana.410340510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Myotonic dystrophy is associated with progressive muscular atrophy. To define the mechanism of muscle wasting in this disease, we studied myofibrillar proteolysis in vivo in 8 men moderately affected with myotonic dystrophy, and compared the results with those of 10 normal men. Myofibrillar proteolysis was estimated by measuring the 3-methylhistidine arteriovenous difference (A-V) and efflux (Q) across the forearm in the postabsorptive state. Plasma 3-methylhistidine concentrations were determined by high-performance liquid chromatography with postcolumn o-phthalaldehyde derivatization and fluorescence detection. Plasma flow to the forearm muscles (F) was estimated to represent 85% of total forearm plasma flow as determined by the indicator-dilution technique. Forearm 3-methylhistidine efflux was calculated as: Q = F(A-V). Mean muscle mass (24-hour creatinine excretion), lean body mass, and forearm volume were decreased in the patients with myotonic dystrophy, confirming the presence of muscle atrophy. Mean forearm 3-methylhistidine arteriovenous difference and efflux were not significantly different in the two groups. We conclude that myofibrillar protein degradation is not increased in myotonic dystrophy, even when measured in a muscle compartment selectively affected by wasting. Muscle atrophy in myotonic dystrophy is probably the result of defective anabolism rather than accelerated catabolism.
Collapse
Affiliation(s)
- Z Rifai
- Department of Neurology, University of Rochester, NY 14642
| | | | | | | |
Collapse
|
31
|
Abstract
It is proposed that an intracellular cycle exists to limit or terminate the insulin signal. The cycle involves increased synthesis of sn-1,2-diacylglycerol (DAG) in response to insulin. The DAG activates protein kinase C (PKC) which phosphorylates glycogen synthase either directly or through other protein kinases to render it inactive. Protein kinase C may also inhibit the insulin receptor by phosphorylation of receptor serine residues. Insulin resistance could then arise as a consequence of a persistent increase in DAG levels. Such an increase could occur in three different ways. Chronic hyperinsulinaemia could increase DAG levels by de-novo synthesis from phosphatidic acid, by hydrolysis of phosphatidylcholine, or by hydrolysis of glycosyl-phosphatidylinositol; DAG is also formed by hydrolysis of phosphatidylinositol 4,5-biphosphate (PIP2). This reaction, known as the 'PI response,' may be the connection between hypertension and insulin resistance. A third mechanism for an increase in DAG involves neural abnormalities. Thus, muscle denervation in the rat is characterized both by a profound insulin resistance and a large increase in DAG. It is possible that a similar increase occurs in humans and may explain the association between denervation, inactivity, and insulin resistance.
Collapse
Affiliation(s)
- E Shmueli
- Department of Medicine, University of Newcastle Upon Tyne, UK
| | | | | |
Collapse
|
32
|
Fantus IG, Janjua N, Senni H, Andermann E. Glucose intolerance in first-degree relatives of patients with Friedreich's ataxia is associated with insulin resistance: evidence for a closely linked inherited trait. Metabolism 1991; 40:788-93. [PMID: 1861628 DOI: 10.1016/0026-0495(91)90004-g] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Multiple and different genetic defects may be associated with the development of diabetes mellitus. Friedreich's ataxia (FA) is an autosomal recessively inherited neurologic disease associated with a high prevalence of diabetes. We previously demonstrated that patients with FA have insulin resistance prior to the development of overt diabetes mellitus. To determine if insulin resistance is an inherited characteristic in this group, we performed oral glucose tolerance tests (OGTT) on first-degree relatives, 21 parents and 17 siblings, of patients with FA. While fasting concentrations were normal, both glucose and insulin concentrations in response to oral glucose were significantly elevated compared with controls. Corrected insulin responses, CIR = I x 100/G (G-70) (I = insulin, G = glucose), were not different from controls, whereas peripheral insulin activities, A = 10(4)/Ip Gp (p = values of I and G at peak glucose concentration), were significantly decreased (FA, 0.66 +/- 0.11, P less than .001; parents, 0.63 +/- 0.06, P less than .001; siblings, 0.72 +/- 0.09, P less than .01; v controls, 1.52 +/- 0.19), indicating the presence of insulin resistance in patients and first-degree relatives. Multiple discriminant analysis was used to separate patients with FA from controls. The combination of GLUT (sum of glucose values 0 to 3 hours of the OGTT) and CIR achieved significant separation (P less than .0004). Subsequent assignment of the relatives showed that 17 of 18 parents and 11 of 16 siblings (69%) fell in the range of FA, rather than with controls. These data suggest that insulin resistance is an inherited trait in this group.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- I G Fantus
- Department of Medicine, Royal Victoria Hospital, Montreal, Quebec, Canada
| | | | | | | |
Collapse
|
33
|
Krentz AJ, Williams AC, Nattrass M. Insulin resistance in multiple aspects of intermediary metabolism in myotonic dystrophy. Metabolism 1991; 40:866-72. [PMID: 1861635 DOI: 10.1016/0026-0495(91)90017-q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The responses of circulating intermediary metabolites to a low-dose incremental insulin infusion (basal, 0.005, 0.01, and 0.05 U.kg-1.h-1) were examined in eight ambulant subjects with the multisystem disorder, myotonic dystrophy. Eight healthy subjects matched for age, gender, and body mass index served as controls. Oral glucose tolerance (75 g) was normal in all subjects. Basal (postabsorptive) hyperinsulinemia was observed in the subjects with myotonic dystrophy (8.4 +/- 2.0 v 2.3 +/- 0.2 mU/L, P less than .01) with increased basal C-peptide levels. Basal blood glycerol (0.09 +/- 0.02 v 0.05 +/- 0.01 mmol/L, P less than .05), lactate (1.14 +/- 0.12 v 0.77 +/- 0.07 mmol/L, P less than .02), and pyruvate (0.08 +/- 0.01 v 0.05 +/- 0.01 mmol/L, P less than .02) were also elevated in these subjects. During the incremental insulin infusion, circulating insulin (F = 8.2, P less than .02) and C-peptide (F = 5.1, P less than .05) levels were significantly higher in the myotonic subjects. Despite the hyperinsulinemia, circulating concentrations of lactate (F = 9.8, P less than .01), pyruvate (7.8, P less than .02), and glycerol (F = 7.5, P less than .02) were also higher in the subjects with myotonic dystrophy, providing prima facie evidence of insulin resistance in the regulation of these metabolites. During the highest insulin rate, isotopically determined metabolic clearance rate of glucose was significantly lower in the myotonic subjects (3.6 +/- 0.4 v 5.5 +/- 0.7 mL.kg-1.min-1, P less than .05), indicating impaired peripheral glucose metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- A J Krentz
- Diabetic Clinic, General Hospital, Birmingham, UK
| | | | | |
Collapse
|
34
|
Krentz AJ, Coles NH, Williams AC, Nattrass M. Abnormal regulation of intermediary metabolism after oral glucose ingestion in myotonic dystrophy. Metabolism 1990; 39:938-42. [PMID: 2202885 DOI: 10.1016/0026-0495(90)90304-u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The responses of plasma insulin and blood intermediary metabolites to oral glucose (75 g) were determined in 10 subjects with myotonic dystrophy. Results were compared with responses in 10 normal control subjects matched for age, sex, and body mass index. Fasting hyperinsulinemia was observed in the myotonic subjects (7.5 +/- 1.6 v 2.4 +/- 0.4 mU/L; P less than .005) and plasma insulin concentration remained significantly higher following oral glucose (F = 38.09; P less than .001). Total cumulative insulin release was markedly higher in the myotonic subjects (4,984.3 v 1,286.6 mU/L; P less than .0001). Basal blood glucose concentration was normal (4.8 +/- 0.2 v 4.7 +/- 0.1 mmol/L), although overall blood glucose was elevated in the myotonic subjects following oral glucose ingestion (F = 5.37; P less than .05). Glucose tolerance was normal in all subjects. Fasting blood lactate was higher in the myotonic subjects (1.31 +/- 0.13 v 0.94 +/- 0.08 mmol/L; P less than .05) and remained significantly elevated following the ingestion of glucose (F = 7.22; P less than .02). Blood pyruvate response was also higher in the myotonic subjects (F = 5.88; P less than .05). Basal blood glycerol was elevated in the myotonic subjects (0.12 +/- 0.02 v 0.05 +/- 0.01 mmol/L; P less than .005) and remained elevated following oral glucose (F = 11.31; P less than .005). No significant overall differences were observed in ketone bodies, alanine, or fatty acids between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
|
35
|
Griggs RC, Jozefowicz R, Kingston W, Nair KS, Herr BE, Halliday D. Mechanism of muscle wasting in myotonic dystrophy. Ann Neurol 1990; 27:505-12. [PMID: 2360792 DOI: 10.1002/ana.410270509] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Myotonic dystrophy is associated with progressive muscular atrophy. In order to determine the mechanism of muscle wasting in this condition, we measured fractional mixed skeletal muscle protein synthesis in the postabsorptive state in 8 patients with myotonic dystrophy, and compared the results with those of 10 normal subjects. Fractional muscle protein synthesis was determined by measuring the increment of 13C leucine in mixed skeletal muscle protein obtained by needle biopsy from the quadriceps muscle during a primed-continuous infusion of L-(1-13C) leucine. We used plasma 13C alpha-ketoisocaproate (representing intracellular leucine labeling) as the precursor pool for the calculation of fractional muscle protein synthesis and leucine kinetics. Fractional muscle protein synthesis was depressed in the patients with myotonic dystrophy (28% decrease, p less than 0.02). Leucine flux, leucine oxidation, and the nonoxidative portion of leucine flux were not different between the patients with myotonic dystrophy and the normal control subjects. Muscle atrophy in myotonic dystrophy reflects a selective decrease in muscle protein synthesis without any similar decrease in nonmuscle protein synthesis. This decrease may result from an impaired end-organ response to anabolic hormones or substrates.
Collapse
Affiliation(s)
- R C Griggs
- Department of Neurology, University of Rochester, School of Medicine, NY 14642
| | | | | | | | | | | |
Collapse
|
36
|
|
37
|
Griggs RC, Halliday D, Kingston W, Moxley RT. Effect of testosterone on muscle protein synthesis in myotonic dystrophy. Ann Neurol 1986; 20:590-6. [PMID: 2431651 DOI: 10.1002/ana.410200506] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Muscle wasting in myotonic dystrophy may result from decreased muscle anabolic processes rather than from increased catabolism. Male patients with myotonic dystrophy often have low levels of circulating androgens, and androgen administration has been shown to increase their muscle mass. We have studied the effect of testosterone enanthate administration (3 mg/kg weekly for 3 months) on muscle and whole body protein synthesis in 6 male patients with myotonic dystrophy. Muscle protein synthesis was estimated from the rate of isotope incorporation into muscle protein obtained by quadriceps muscle biopsy during a primed continuous infusion of L-[1-13C]leucine. Testosterone administration resulted in a significant increase in muscle protein synthesis in all patients. Whole body protein synthesis did not increase, indicating that protein synthesis in other tissues may have declined. Muscle ribonucleic acid content rose significantly in response to testosterone administration, suggesting that testosterone initiated its effect by hormone receptor interaction with muscle nuclei.
Collapse
|
38
|
Khan RJ, Andermann E, Fantus IG. Glucose intolerance in Friedreich's ataxia: association with insulin resistance and decreased insulin binding. Metabolism 1986; 35:1017-23. [PMID: 3534514 DOI: 10.1016/0026-0495(86)90037-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Friedreich's Ataxia (FA) is a neurologic disorder associated with a high prevalence of diabetes mellitus. To assess insulin secretion and insulin resistance, glucose and insulin responses to oral glucose and insulin binding to circulating monocytes and dextran gradient fractionated and unfractionated red blood cells (RBCs) were compared in 11 subjects with FA to 11 age-matched controls. Glucose and insulin responses were elevated from one to three hours after oral glucose in FA. The mean corrected insulin responses were not different while peripheral insulin activity (A) was significantly decreased (1.38 +/- 0.22 v 0.77 +/- 0.16, control v FA, P less than 0.025) indicating the presence of insulin resistance. A significant correlation between the degree of insulin resistance (A) and duration of neurologic symptoms was found (r = .65. P less than 0.025). Resistance to exogenous insulin was confirmed in ten subjects with FA by intravenous insulin tolerance tests (KITT, %/min, 6.25 +/- 0.90 v 3.93 +/- 0.61, P less than .05). Both FA and control groups showed highest insulin binding to fraction A (youngest) RBCs, but no difference was observed between the two groups. However, insulin binding to monocytes was significantly decreased in subjects with FA (% specific binding/10(7) cells/mL, 6.37 +/- 0.71 v 4.51 +/- 0.39, P less than 0.05, control v FA). This was associated with a decrease in apparent receptor affinity. We conclude that FA is associated with insulin resistance, which increases with the duration of neurologic impairment. The insulin binding to monocytes suggests that the insulin resistance may be partially explained by a receptor defect.
Collapse
|
39
|
Abstract
Patients with myotonic dystrophy are markedly insulin resistant and have an associated abnormality in the regulation of arterialized amino acid concentrations during euglycemic insulin infusions. We studied the effect of testosterone treatment on whole body amino acid balance in myotonic dystrophy, since it increases muscle mass and muscle protein synthesis rate. Six patients with myotonic dystrophy underwent studies of glucose disposal and amino acid regulation during low dose insulin infusions with maintenance of euglycemia, prior to and after 10 to 13 weeks of testosterone (3 mg/kg/wk). Testosterone increased the insulin-stimulated decline of certain amino acids, but did not improve whole body glucose uptake. The anabolic effect of testosterone is separate from the anabolic effect of insulin.
Collapse
|
40
|
Kingston WJ, Livingston JN, Moxley RT. Enhancement of insulin action after oral glucose ingestion. J Clin Invest 1986; 77:1153-62. [PMID: 3082935 PMCID: PMC424451 DOI: 10.1172/jci112416] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Previous investigations in normal humans and rats have shown an increase in insulin sensitivity and binding affinity of adipocytes isolated 1-3 h after glucose ingestion. To determine whether a rapid enhancement of the action of insulin follows glucose ingestion in vivo, the present studies have utilized 120-min 20 mU/m2 X min euglycemic insulin infusions before and after 7.5-, 15-, 25-, and 100-g oral glucose loads. Euglycemic insulin infusions after the carbohydrate challenge were begun after arterialized blood glucose and insulin values had returned to baseline. After 15- and 25-g oral glucose loads during the 20-120-min interval of insulin infusion, glucose infusion rates increased by 44 +/- 6% (P less than 0.0001) and 47 +/- 9% (P less than 0.0002), respectively. No significant differences in arterialized glucose or insulin values existed between basal and post-glucose insulin infusions. In addition, no significant differences in hepatic glucose production or counter-regulatory hormone levels were found between basal and post-glucose insulin infusions. Control infusion studies including subjects who ingested saline or mannitol failed to show an increase in insulin action. Studies were carried out to mimic the insulin curve seen after 15- and 25-g oral glucose loads. Euglycemic insulin infusions after these insulin simulation studies show a 34 +/- 7% enhancement compared to baseline euglycemic insulin infusions. These results demonstrate a rapid enhancement of insulin action after oral glucose challenge in normal humans. The insulin simulation studies suggest that insulin itself either directly or through release of another factor acts on muscle to increase insulin sensitivity. The increase in insulin action demonstrated in these investigations may represent an important regulatory mechanism to modulate tissue insulin sensitivity.
Collapse
|
41
|
Halliday D, Ford GC, Edwards RH, Rennie MJ, Griggs RC. In vivo estimation of muscle protein synthesis in myotonic dystrophy. Ann Neurol 1985; 17:65-9. [PMID: 3985589 DOI: 10.1002/ana.410170115] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The rate of muscle protein synthesis in patients with myotonic dystrophy has been studied, and results correlated with total muscle mass. Whole body and skeletal muscle protein synthesis were estimated by stable isotope methodology with a primed, continuous infusion of 1-[13C]leucine with measurement of incorporation of [13C]leucine into muscle protein in biopsy samples. Whole body leucine flux, protein synthesis, and protein breakdown were only slightly depressed, but muscle protein synthesis was markedly decreased, in myotonic dystrophy. This depression of muscle protein synthesis in myotonic dystrophy correlates with previous observations of impaired insulin-induced muscle uptake of amino acids and supports the suggestion that muscle wasting in this disease is the consequence of defective anabolism in muscle.
Collapse
|
42
|
Karpati G. Abnormal insulin homeostasis in myotonic dystrophy. Trends Neurosci 1985. [DOI: 10.1016/0166-2236(85)90057-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
43
|
Abstract
A study has been made of the I125 insulin binding and postbinding effects on excised soleus muscles from the 129 ReJ strain of dystrophic mice. Results are compared with those in sex- and weight-matched controls. The data suggest that, in the range of physiological hormone concentrations, the affinity of insulin receptors on dystrophic muscles is less than normal and that the insulin-dependent uptake of both 2-deoxyglucose (2-DG) and aminoisobutyric acid (AIB) is impaired. These findings are taken to indicate that many of the biochemical and electrophysiological abnormalities observed in murine dystrophy could arise from some genetic defect in the receptor proteins controlling uptake of raw materials.
Collapse
|
44
|
Abstract
To quantitate the degree of whole body insulin resistance in patients with myotonic dystrophy, three separate euglycemic insulin infusions were given to ambulatory patients and the results compared with findings in normal control subjects. Basal glucose and insulin values were similar for the two groups. There was no significant difference in insulin clearance rates between normal subjects and patients at the three insulin infusion rates used. A highly significant decrease in the whole body glucose disposal rate was seen during the 120-minute insulin infusion in the patients with myotonic dystrophy compared with normal subjects at all three insulin dosages (20 mU/m2/min: 2.18 +/- 0.29 [standard error] versus 5.49 +/- 1.72 mg/kg/min, p less than 0.0001; 80 mU/m2/min: 4.16 +/- 0.34 versus 8.49 +/- 0.45 mg/kg/min, p less than 0.0001; 200 mU/m2/min: 5.22 +/- 0.53 versus 10.06 +/- 0.50 mg/kg/min, p less than 0.0001). These marked decreases in glucose disposal rates for the patients were adjusted in accordance with their 24-hour urinary creatinine excretion rate to correct for the difference in muscle mass between patients and controls. This adjusted glucose disposal rate was 15 to 25% lower (p less than 0.02) in the patients with myotonic dystrophy at insulin infusion rates of 20 and 80 mU. During the 200 mU insulin infusions, the adjusted glucose disposal rate remained lower than that in normal subjects but was of borderline statistical significance. These studies suggest that moderately severe whole body insulin resistance is responsible for the postprandial hyperinsulinemia typically seen in patients with myotonic dystrophy.
Collapse
|
45
|
Griggs RC, Rennie MJ. Muscle wasting in muscular dystrophy: decreased protein synthesis or increased degradation? Ann Neurol 1983; 13:125-32. [PMID: 6338807 DOI: 10.1002/ana.410130204] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
46
|
Fratino P, Bellomo G, Bellazzi R, Nicotera PL, Sandrini G, Nappi G. Insulin receptors in myotonic dystrophy: a study with mononuclear leucocytes and erythrocytes. ITALIAN JOURNAL OF NEUROLOGICAL SCIENCES 1982; 3:99-106. [PMID: 6749756 DOI: 10.1007/bf02043939] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We evaluated insulin receptor activity on mononuclear leucocytes and erythrocytes in 9 patients with myotonic dystrophy and in 9 controls. The results demonstrated that in myotonic dystrophy: 1. insulin binding to specific receptors was significantly impaired (P less than 0.01) because of a reduction in the number of high and low affinity receptors. 2. the affinity constants were not significantly affected 3. there was no correlation between receptor activity, insulin behaviour and glucose tolerance. These data obtained in two different cellular systems suggest that the constant numerical reduction of insulin receptors was probably due to a systemic membrane defect, typical of myotonic dystrophy.
Collapse
|
47
|
Durelli L, Mutani R, Fassio F, Satta A, Bartoli E. Taurine and hyperexcitable human muscle: effects of taurine on potassium-induced hyperexcitability of dystrophic myotonic and normal muscles. Ann Neurol 1982; 11:258-65. [PMID: 7092178 DOI: 10.1002/ana.410110305] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Progressively increasing concentrations of potassium chloride in Evans blue saline were administered to patients affected with myotonic dystrophy and to healthy volunteers before and after parenteral treatment with taurine. Excitability changes of thenar eminence muscles were related to the venous potassium and chloride concentrations. The actual electrolyte concentrations were compared to those to be expected if no infused electrolytes had been transported into cells. The expected concentrations were calculated by means of Evans blue dilution. This method permitted quantification of changes of muscle-excitability in terms of the potassium chloride concentration capable of disturbing the electrical activity of the studied muscles. The method also provided an indirect evaluation of electrolyte movements across muscle membrane in vivo in humans. Dystrophic myotonic muscles appeared highly sensitive to extracellular potassium and, unlike normal muscles, were unable to accumulate potassium-induced muscle hyperexcitability and favored electrolyte accumulation in dystrophic myotonic muscles. The stabilizing effect of taurine is discussed in relation to its ability to increase intracellular potassium concentration, membrane conductance, or both.
Collapse
|
48
|
Moxley RT, Livingston JN, Lockwood DH, Griggs RC, Hill RL. Abnormal regulation of monocyte insulin-binding affinity after glucose ingestion in patients with myotonic dystrophy. Proc Natl Acad Sci U S A 1981; 78:2567-71. [PMID: 7017735 PMCID: PMC319390 DOI: 10.1073/pnas.78.4.2567] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Insulin insensitivity of uncertain etiology often exists in myotonic muscular dystrophy, a multitissue, autosomal dominant disorder hypothesized to be a hereditary membrane disease. The present studies show that monocytes from patients with myotonic dystrophy fail to demonstrate the normally observed qualitative increase in insulin-binding affinity after oral glucose loading. Monocytes from 10 normal volunteers developed a significantly increased insulin-binding affinity by 2 hr after glucose ingestion (mean +/- SEM, 11.7 +/- 2.7 ng/ml compared to basal 50% insulin displacement value of 23.3 +/- 2.2 ng/ml, P less than 0.005). This increase was maintained at 5 hr (13.5 +/- 2.7 ng/ml, P less than 0.05). In contrast, no significant increase in monocyte insulin-binding affinity occurred in cells from nine myotonic dystrophy patients at 2 and 5 hr after glucose loading (50% insulin displacement values: basal, 14.2 +/- 2.8 ng/ml; 2 hr, 16.7 +/- 1.7 ng/ml; 5 hr, 10.8 +/- 2.1 ng/ml). These alterations document the presence of abnormalities in the insulin receptor or receptor-associated processes that modulate insulin binding. A hereditary plasma membrane defect may underlie these findings. This abnormality may have an etiologic role in the decreased insulin sensitivity that frequently afflicts patients with myotonic dystrophy.
Collapse
|
49
|
Rizza RA, Mandarino LJ, Gerich JE. Mechanisms of insulin resistance in man. Assessment using the insulin dose-response curve in conjunction with insulin-receptor binding. Am J Med 1981; 70:169-76. [PMID: 7006389 DOI: 10.1016/0002-9343(81)90423-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During the past few years it has become increasingly apparent that insulin resistance may be a more frequent cause of carbohydrate intolerance or contributing factor in carbohydrate intolerance than was hitherto appreciated. Abnormal insulin action may result from prereceptor, receptor or postreceptor defects. These may be manifested by an increase in the concentration of insulin necessary for a half-maximal effect (decreased sensitivity) or a decrease in the maximal response to insulin (decreased responsiveness), or both. Alterations in sensitivity and responsiveness to insulin can be distinguished only by evaluating insulin dose-response curves. When used in conjunction with measurements of insulin binding to its receptor, the characteristics of these curves can provide insight into the mechanism or mechanisms responsible for insulin resistance.
Collapse
|
50
|
Li JB. Protein synthesis and degradation in skeletal muscle of normal and dystrophic hamsters. THE AMERICAN JOURNAL OF PHYSIOLOGY 1980; 239:E401-6. [PMID: 6160771 DOI: 10.1152/ajpendo.1980.239.6.e401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Dystrophic hamsters (BIO 53.58) had lower body weights and gastrocnemius muscle weights than normal hamsters (BIO RB). Dystrophic muscle contained less protein than normal muscle. The proportion of collagenous to noncollagenous protein remained unchanged. Loss of protein in the dystrophic muscle was the result of an increase in the rate of protein degradation. This was accompanied by higher activities of two lysosomal proteases, cathepsins B and D. The net effect of the increase in protein degradation was blunted by an increase in the rate of synthesis of total protein and myosin. The faster rate of synthesis in dystrophic muscle was partially due to an increase in the concentration of cellular RNA. Rates of peptide-chain initiation and protein synthesis decreased in muscles of normal hamsters perfused in the absence of insulin. In the presence of insulin, these processes were maintained at higher rates. However, the rate of protein synthesis in dystrophic muscle appeared less insulin-dependent than normal muscle. Protein degradation was inhibited by insulin in both types of muscle.
Collapse
|