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Wei C, Benzow K, Koob MD, Gomez CM, Du X. Correction: The Transcription Factor, α1ACT, Acts Through a MicroRNA Network to Regulate Neurogenesis and Cell Death During Neonatal Cerebellar Development. Cerebellum 2024; 23:876. [PMID: 37198370 PMCID: PMC10950944 DOI: 10.1007/s12311-023-01567-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Affiliation(s)
- Cenfu Wei
- Department of Neurology, University of Chicago, Chicago, IL, 60637, USA
| | - Kellie Benzow
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Michael D Koob
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA
| | | | - Xiaofei Du
- Department of Neurology, University of Chicago, Chicago, IL, 60637, USA.
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Benzow K, Karanjeet K, Oblak AL, Carter GW, Sasner M, Koob MD. Gene replacement-Alzheimer's disease (GR-AD): Modeling the genetics of human dementias in mice. Alzheimers Dement 2024; 20:3080-3087. [PMID: 38343132 PMCID: PMC11032548 DOI: 10.1002/alz.13730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/11/2024] [Accepted: 01/15/2024] [Indexed: 03/07/2024]
Abstract
INTRODUCTION Genetic studies conducted over the past four decades have provided us with a detailed catalog of genes that play critical roles in the etiology of Alzheimer's disease (AD) and related dementias (ADRDs). Despite this progress, as a field we have had only limited success in incorporating this rich complexity of human AD/ADRD genetics findings into our animal models of these diseases. Our primary goal for the gene replacement (GR)-AD project is to develop mouse lines that model the genetics of AD/ADRD as closely as possible. METHODS To do this, we are generating mouse lines in which the genes of interest are precisely and completely replaced in the mouse genome by their full human orthologs. RESULTS Each model set consists of a control line with a wild-type human allele and variant lines that precisely match the human genomic sequence in the control line except for a high-impact pathogenic mutation or risk variant.
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Affiliation(s)
- Kellie Benzow
- Laboratory Medicine and Pathology, and Institute for Translational Neuroscience University of MinnesotaMinneapolisMinnesotaUSA
| | - Kul Karanjeet
- Laboratory Medicine and Pathology, and Institute for Translational Neuroscience University of MinnesotaMinneapolisMinnesotaUSA
| | | | | | | | - Michael D. Koob
- Laboratory Medicine and Pathology, and Institute for Translational Neuroscience University of MinnesotaMinneapolisMinnesotaUSA
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Duvick L, Southern WM, Benzow KA, Burch ZN, Handler HP, Mitchell JS, Kuivinen H, Gadiparthi U, Yang P, Soles A, Sheeler CA, Rainwater O, Serres S, Lind EB, Nichols-Meade T, You Y, O'Callaghan B, Zoghbi HY, Cvetanovic M, Wheeler VC, Ervasti JM, Koob MD, Orr HT. Mapping SCA1 regional vulnerabilities reveals neural and skeletal muscle contributions to disease. JCI Insight 2024; 9:e176057. [PMID: 38512434 DOI: 10.1172/jci.insight.176057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 03/19/2024] [Indexed: 03/23/2024] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by an expanded polyglutamine tract in the widely expressed ataxin-1 (ATXN1) protein. To elucidate anatomical regions and cell types that underlie mutant ATXN1-induced disease phenotypes, we developed a floxed conditional knockin mouse (f-ATXN1146Q/2Q) with mouse Atxn1 coding exons replaced by human ATXN1 exons encoding 146 glutamines. f-ATXN1146Q/2Q mice manifested SCA1-like phenotypes including motor and cognitive deficits, wasting, and decreased survival. Central nervous system (CNS) contributions to disease were revealed using f-ATXN1146Q/2Q;Nestin-Cre mice, which showed improved rotarod, open field, and Barnes maze performance by 6-12 weeks of age. In contrast, striatal contributions to motor deficits using f-ATXN1146Q/2Q;Rgs9-Cre mice revealed that mice lacking ATXN1146Q/2Q in striatal medium-spiny neurons showed a trending improvement in rotarod performance at 30 weeks of age. Surprisingly, a prominent role for muscle contributions to disease was revealed in f-ATXN1146Q/2Q;ACTA1-Cre mice based on their recovery from kyphosis and absence of muscle pathology. Collectively, data from the targeted conditional deletion of the expanded allele demonstrated CNS and peripheral contributions to disease and highlighted the need to consider muscle in addition to the brain for optimal SCA1 therapeutics.
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Affiliation(s)
- Lisa Duvick
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - W Michael Southern
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Kellie A Benzow
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Zoe N Burch
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Hillary P Handler
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Jason S Mitchell
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Hannah Kuivinen
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Udaya Gadiparthi
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Praseuth Yang
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Alyssa Soles
- Institute of Translational Neuroscience
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Carrie A Sheeler
- Institute of Translational Neuroscience
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Orion Rainwater
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Shannah Serres
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Erin B Lind
- Institute of Translational Neuroscience
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Tessa Nichols-Meade
- Institute of Translational Neuroscience
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yun You
- Mouse Genetics Laboratory, University of Minnesota, Minneapolis. Minnesota, USA
| | - Brennon O'Callaghan
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Huda Y Zoghbi
- Departments of Molecular and Human Genetics, Pediatrics, and Howard Hughes Medical Institute, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, USA
| | - Marija Cvetanovic
- Institute of Translational Neuroscience
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Vanessa C Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Michael D Koob
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
| | - Harry T Orr
- Institute of Translational Neuroscience
- Department of Laboratory Medicine and Pathology, and
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Wei C, Benzow K, Koob MD, Gomez CM, Du X. The Transcription Factor, α1ACT, Acts Through a MicroRNA Network to Regulate Neurogenesis and Cell Death During Neonatal Cerebellar Development. Cerebellum 2023; 22:651-662. [PMID: 35729466 PMCID: PMC10307715 DOI: 10.1007/s12311-022-01431-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/09/2022] [Indexed: 11/29/2022]
Abstract
MicroRNAs, a class of small RNA regulators, function throughout neurodevelopment, from neural stem cell neurogenesis to neuronal maturation, synaptic formation, and plasticity. α1ACT, a transcription factor (TF), plays a critical role in neonatal cerebellar development by regulating an ensemble of genes. Of these, ChIP-seq analysis matched near 50% genes directly regulated by α1ACT. Yet, more than half the regulated transcripts lacked direct interaction with α1ACT. To investigate whether α1ACT acts through a microRNA network, we studied α1ACT-associated simultaneous miRNA:mRNA transcriptome profiles, using miRNA-seq paired with RNA-seq. Thirty-one differentially expressed miRNAs (DEMs) associated with α1ACT-regulated differentially expressed genes (DEGs) were profiled in α1ACT-overexpressing PC12 cells and were further validated in neonatal transgenic mouse cerebellum overexpressing α1ACT in a context-dependent manner. Here, we also demonstrated that α1ACT facilitates neurogenesis and development of dendritic synapses and is partially a result of the downregulation of the miR-99 cluster, miR-143, miR-23, miR-146, miR-363, and miR-484. On the other hand, the miR-181, miR-125, and miR-708 clusters were upregulated by α1ACT, which inhibit MAPK signaling and cell death pathways by targeting Ask1, Odc1, Atf4, and Nuf2 for decreased expression. MiR-181a-5p was verified as the most abundant DEM in neonatal cerebellum, which was further induced by α1ACT. Overall, under α1ACT modulation, up-/downregulated miRNA clusters with their paired target genes may form a regulatory network controlling the balance between the neuronal proliferation, differentiation, and cell death in the cerebellum to promote neonatal development. Our findings concerning the α1ACT-related miRNA/mRNA expression profiles in neonatal cerebellum may inform future investigations for cerebellar development.
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Affiliation(s)
- Cenfu Wei
- Department of Neurology, University of Chicago, Chicago, IL, 60637, USA
| | - Kellie Benzow
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Michael D Koob
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, 55455, USA
| | | | - Xiaofei Du
- Department of Neurology, University of Chicago, Chicago, IL, 60637, USA.
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Duvick L, Southern WM, Benzow K, Burch ZN, Handler HP, Mitchell JS, Kuivinen H, Gadiparthi UK, Yang P, Soles A, Scheeler C, Rainwater O, Serres S, Lind E, Nichols-Meade T, O'Callaghan B, Zoghbi HY, Cvetanovic M, Wheeler VC, Ervasti JM, Koob MD, Orr HT. Delineating regional vulnerability in the neurodegenerative disease SCA1 using a conditional mutant ATXN1 mouse. bioRxiv 2023:2023.02.08.527710. [PMID: 36798410 PMCID: PMC9934664 DOI: 10.1101/2023.02.08.527710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by an expanded polyglutamine tract in the widely expressed ATXN1 protein. To elucidate anatomical regions and cell types that underlie mutant ATXN1-induced disease phenotypes, we developed a floxed conditional knockout mouse model ( f-ATXN1 146Q/2Q ) having mouse Atxn1 coding exons replaced by human exons encoding 146 glutamines. F-ATXN1 146Q/2Q mice manifest SCA1-like phenotypes including motor and cognitive deficits, wasting, and decreased survival. CNS contributions to disease were revealed using ATXN1 146Q/2Q ; Nestin-Cre mice, that showed improved rotarod, open field and Barnes maze performances. Striatal contributions to motor deficits were examined using f-ATXN1 146Q/2Q ; Rgs9-Cre mice. Mice lacking striatal ATXN1 146Q/2Q had improved rotarod performance late in disease. Muscle contributions to disease were revealed in f-ATXN1 146Q/2Q ; ACTA1-Cre mice which lacked muscle pathology and kyphosis seen in f-ATXN1 146Q/2Q mice. Kyphosis was not improved in f-ATXN1 146Q/2Q ;Nestin - Cre mice. Thus, optimal SCA1 therapeutics will require targeting mutant ATXN1 toxic actions in multiple brain regions and muscle.
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Perissinotti PP, Martínez-Hernández E, He Y, Koob MD, Piedras-Rentería ES. Genetic Deletion of KLHL1 Leads to Hyperexcitability in Hypothalamic POMC Neurons and Lack of Electrical Responses to Leptin. Front Neurosci 2021; 15:718464. [PMID: 34566565 PMCID: PMC8458657 DOI: 10.3389/fnins.2021.718464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/05/2021] [Indexed: 11/13/2022] Open
Abstract
Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltage-gated calcium channels. The KLHL1 knockout (KO) model displays altered calcium channel expression in various brain regions. We analyzed the electrical behavior of hypothalamic POMC (proopiomelanocortin) neurons and their response to leptin. Leptin's effects on POMC neurons include enhanced gene expression, activation of the ERK1/2 pathway and increased electrical excitability. The latter is initiated by activation of the Jak2-PI3K-PLC pathway, which activates TRPC1/5 (Transient Receptor Potential Cation) channels that in turn recruit T-type channel activity resulting in increased excitability. Here we report over-expression of CaV3.1 T-type channels in the hypothalamus of KLHL1 KO mice increased T-type current density and enhanced POMC neuron basal excitability, rendering them electrically unresponsive to leptin. Electrical sensitivity to leptin was restored by partial blockade of T-type channels. The overexpression of hypothalamic T-type channels in POMC neurons may partially contribute to the obese and abnormal feeding phenotypes observed in KLHL1 KO mice.
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Affiliation(s)
- Paula P Perissinotti
- Cell and Molecular Physiology Department and Neuroscience Division of the Cardiovascular Research Institute, Loyola University Chicago, Maywood, IL, United States
| | - Elizabeth Martínez-Hernández
- Cell and Molecular Physiology Department and Neuroscience Division of the Cardiovascular Research Institute, Loyola University Chicago, Maywood, IL, United States
| | - Yungui He
- Institute for Translational Neuroscience and Department of Lab Medicine & Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Michael D Koob
- Institute for Translational Neuroscience and Department of Lab Medicine & Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Erika S Piedras-Rentería
- Cell and Molecular Physiology Department and Neuroscience Division of the Cardiovascular Research Institute, Loyola University Chicago, Maywood, IL, United States
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Castro M, Venkateswaran N, Peters ST, Deyle DR, Bower M, Koob MD, Boeve BF, Vossel K. Case Report: Early-Onset Behavioral Variant Frontotemporal Dementia in Patient With Retrotransposed Full-Length Transcript of Matrin-3 Variant 5. Front Neurol 2020; 11:600468. [PMID: 33408686 PMCID: PMC7779795 DOI: 10.3389/fneur.2020.600468] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 11/19/2020] [Indexed: 11/13/2022] Open
Abstract
Frontotemporal dementia (FTD) rarely occurs in individuals under the age of 30, and genetic causes of early-onset FTD are largely unknown. The current report follows a 27 year-old patient with no significant past medical history presenting with two years of progressive changes in behavior, rushed speech, verbal aggression, and social withdrawal. MRI and FDG-PET imaging of the brain revealed changes maximally in the frontal and temporal lobes, which along with the clinical features, are consistent with behavioral variant FTD. Next generation sequencing of a panel of 28 genes associated with dementia and amyotrophic lateral sclerosis (ALS) initially revealed a duplication of exon 15 in Matrin-3 (MATR3). Whole genome sequencing determined that this genetic anomaly was, in fact, a sequence corresponding with full-length MATR3 variant 5 inserted into chromosome 12, indicating retrotransposition from a messenger RNA intermediate. To our knowledge, this is a novel mutation of MATR3, as the majority of mutations in MATR3 linked to FTD-ALS are point mutations. Genomic DNA analysis revealed that this mutation is also present in one unaffected first-degree relative and one unaffected second-degree relative. This suggests that the mutation is either a disease-causing mutation with incomplete penetrance, which has been observed in heritable FTD, or a benign variant. Retrotransposons are not often implicated in neurodegenerative diseases; thus, it is crucial to clarify the potential role of this MATR3 variant 5 retrotransposition in early-onset FTD.
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Affiliation(s)
- Madelyn Castro
- Department of Neurology, N. Bud Grossman Center for Memory Research and Care, University of Minnesota, Minneapolis, MN, United States
| | - Nisha Venkateswaran
- Department of Neurology, N. Bud Grossman Center for Memory Research and Care, University of Minnesota, Minneapolis, MN, United States.,Department of Neurology, Mary S. Easton Center for Alzheimer's Disease Research at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Samuel T Peters
- Department of Neurology, N. Bud Grossman Center for Memory Research and Care, University of Minnesota, Minneapolis, MN, United States
| | - David R Deyle
- Department of Clinical Genomics, Mayo Clinic Rochester, Rochester, MN, United States
| | - Matthew Bower
- Division of Genetics and Metabolism, University of Minnesota, Minneapolis, MN, United States.,Molecular Diagnostics Laboratory, M Health-Fairview, University of Minnesota, Minneapolis, MN, United States
| | - Michael D Koob
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Bradley F Boeve
- Department of Neurology, Mayo Clinic Rochester, Rochester, MN, United States
| | - Keith Vossel
- Department of Neurology, N. Bud Grossman Center for Memory Research and Care, University of Minnesota, Minneapolis, MN, United States.,Department of Neurology, Mary S. Easton Center for Alzheimer's Disease Research at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.,Institute for Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN, United States
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Yoon YG, Koob MD. Intramitochondrial transfer and engineering of mammalian mitochondrial genomes in yeast. Mitochondrion 2019; 46:15-21. [PMID: 30980913 DOI: 10.1016/j.mito.2019.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/19/2018] [Accepted: 03/20/2019] [Indexed: 01/17/2023]
Abstract
Mitochondrial genomes (mtDNA) depend on the nuclear genome with which they have evolved to provide essential replication functions and have been known to replicate as xenotransplants only in the cells of closely related species. We now report that complete mouse mitochondrial genomes can be stably transplanted into the mitochondrial network in yeast devoid of their own mtDNA. Our analyses of these xenomitochondrial yeast cells show that they are accurately replicating intact mouse mtDNA genomes without rearrangement and that these mtDNA genomes have the same overall topology as the mtDNA present in the mouse mitochondrial network (i.e., circular monomers). Moreover, non-mtDNA replication and selection sequences required for maintaining the mitochondrial genomes in bacterial hosts are dispensable in these yeast mitochondria and could be efficiently and seamlessly removed by targeted homologous recombination within the mitochondria. These findings demonstrate that the yeast mtDNA replication system is capable of accurately replicating intact mammalian mtDNA genomes without sequence loss or rearrangement and that yeast mitochondria are a highly versatile host system for engineering complete mammalian mitochondrial genomes.
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Affiliation(s)
- Young Geol Yoon
- Department of Biomedical Science, Jungwon University, 85 Munmu-ro, Goesan-eup, Goesan-gun, Chungbuk 28024, Republic of Korea.
| | - Michael D Koob
- Institutes for Translational Neuroscience (ITN) & of Human Genetics (IHG), Department of Laboratory Medicine and Pathology, University of Minnesota, Wallin Medical Bioscience Building, 2101 6th St SE, Minneapolis, MN 55455, United States.
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Perissinotti PP, Ethington EA, Almazan E, Martínez-Hernández E, Kalil J, Koob MD, Piedras-Rentería ES. Calcium current homeostasis and synaptic deficits in hippocampal neurons from Kelch-like 1 knockout mice. Front Cell Neurosci 2015; 8:444. [PMID: 25610372 PMCID: PMC4285801 DOI: 10.3389/fncel.2014.00444] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/10/2014] [Indexed: 11/30/2022] Open
Abstract
Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltage-gated CaV2.1 (P/Q-type) and CaV3.2 (α1H T-type) calcium channels; KLHL1 knockdown experiments (KD) cause down-regulation of both channel types and altered synaptic properties in cultured rat hippocampal neurons (Perissinotti et al., 2014). Here, we studied the effect of ablation of KLHL1 on calcium channel function and synaptic properties in cultured hippocampal neurons from KLHL1 knockout (KO) mice. Western blot data showed the P/Q-type channel α1A subunit was less abundant in KO hippocampus compared to wildtype (WT); and P/Q-type calcium currents were smaller in KO neurons than WT during early days in vitro, although this decrease was compensated for at late stages by increases in L-type calcium current. In contrast, T-type currents did not change in culture. However, biophysical properties and western blot analysis revealed a differential contribution of T-type channel isoforms in the KO, with CaV3.2 α1H subunit being down-regulated and CaV3.1 α1G up-regulated. Synapsin I levels were also reduced in the KO hippocampus and cultured neurons displayed a concomitant reduction in synapsin I puncta and decreased miniature excitatory postsynaptic current (mEPSC) frequency. In summary, genetic ablation of the calcium channel modulator resulted in compensatory mechanisms to maintain calcium current homeostasis in hippocampal KO neurons; however, synaptic alterations resulted in a reduction of excitatory synapse number, causing an imbalance of the excitatory-inhibitory synaptic input ratio favoring inhibition.
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Affiliation(s)
- Paula P Perissinotti
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA
| | - Elizabeth A Ethington
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA
| | - Erik Almazan
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA
| | - Elizabeth Martínez-Hernández
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA
| | - Jennifer Kalil
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA
| | - Michael D Koob
- Department of Laboratory Medicine and Pathology, Institute for Translational Neuroscience, University of Minnesota Minneapolis, MN, USA
| | - Erika S Piedras-Rentería
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA ; Neuroscience Institute, Loyola University Chicago, Stritch School of Medicine Maywood, IL, USA
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Aromolaran KA, Benzow KA, Cribbs L, Koob MD, Piedras-Renteria ES. Kelch-like 1 protein up-regulates T-type currents by an actin-F dependent increase in α1H channels via the recycling endosome. Channels (Austin) 2014; 3:402-12. [DOI: 10.4161/chan.3.6.9858] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Perissinotti PP, Ethington EG, Cribbs L, Koob MD, Martin J, Piedras-Rentería ES. Down-regulation of endogenous KLHL1 decreases voltage-gated calcium current density. Cell Calcium 2014; 55:269-80. [PMID: 24703904 DOI: 10.1016/j.ceca.2014.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 03/04/2014] [Accepted: 03/09/2014] [Indexed: 10/25/2022]
Abstract
The actin-binding protein Kelch-like 1 (KLHL1) can modulate voltage-gated calcium channels in vitro. KLHL1 interacts with actin and with the pore-forming subunits of Cav2.1 and CaV3.2 calcium channels, resulting in up-regulation of P/Q and T-type current density. Here we tested whether endogenous KLHL1 modulates voltage gated calcium currents in cultured hippocampal neurons by down-regulating the expression of KLHL1 via adenoviral delivery of shRNA targeted against KLHL1 (shKLHL1). Control adenoviruses did not affect any of the neuronal properties measured, yet down-regulation of KLHL1 resulted in HVA current densities ~68% smaller and LVA current densities 44% smaller than uninfected controls, with a concomitant reduction in α(1A) and α(1H) protein levels. Biophysical analysis and western blot experiments suggest Ca(V)3.1 and 3.3 currents are also present in shKLHL1-infected neurons. Synapsin I levels, miniature postsynaptic current frequency, and excitatory and inhibitory synapse number were reduced in KLHL1 knockdown. This study corroborates the physiological role of KLHL1 as a calcium channel modulator and demonstrates a novel, presynaptic role.
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Affiliation(s)
- Paula P Perissinotti
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Elizabeth G Ethington
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Leanne Cribbs
- Office of Research Services, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Michael D Koob
- Institute for Translational Neuroscience, Department of Lab Medicine & Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jody Martin
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA; Neuroscience Institute, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA
| | - Erika S Piedras-Rentería
- Cell and Molecular Physiology Department, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA; Neuroscience Institute, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA.
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12
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Piedras‐Renteria ES, Perissinotti PP, Ethington EG, He Y, Martin J, Cribbs L, Koob MD. The Kelch‐Like 1 Actin Binding Protein Modulates Neuronal Voltage Gated Calcium Channels. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.913.51] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Yungui He
- Institute of Human Genetics and Dept. of Lab Medicine & PathologyUniversity of MinnesotaMinneapolisMN
| | - Jody Martin
- PhysiologyLoyola University ChicagoMaywoodIL
| | | | - Michael D Koob
- Institute of Human Genetics and Dept. of Lab Medicine & PathologyUniversity of MinnesotaMinneapolisMN
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Abstract
We have developed a new method for introducing large numbers of isolated mitochondria into tissue culture cells. Direct microinjection of mitochondria into typical mammalian cells has been found to be impractical due to the large size of mitochondria relative to microinjection needles. To circumvent this problem, we inject isolated mitochondria through appropriately sized microinjection needles into rodent oocytes or single-cell embryos, which are much larger than tissue culture cells, and then withdraw a ‘mitocytoplast’ cell fragment containing the injected mitochondria using a modified holding needle. These mitocytoplasts are then fused to recipient cells through viral-mediated membrane fusion and the injected mitochondria are transferred into the cytoplasm of the tissue culture cell. Since mouse oocytes contain large numbers of mouse mitochondria that repopulate recipient mouse cells along with the injected mitochondria, we used either gerbil single-cell embryos or rat oocytes to package injected mouse mitochondria. We found that the gerbil mitochondrial DNA (mtDNA) is not maintained in recipient rho0 mouse cells and that rat mtDNA initially replicated but was soon completely replaced by the injected mouse mtDNA, and so with both procedures mouse cells homoplasmic for the mouse mtDNA in the injected mitochondria were obtained.
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Affiliation(s)
- Yi-Wei Yang
- Graduate Program in Molecular Cellular Developmental Biology and Genetics, Institutes for Translational Neuroscience & of Human Genetics, University of Minnesota, Medical Bioscience Building, 2101 6th St SE, Minneapolis, Minnesota 55455, USA
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Yoon YG, Koob MD, Yoo YH. Mitochondrial genome-maintaining activity of mouse mitochondrial transcription factor A and its transcript isoform in Saccharomyces cerevisiae. Gene 2011; 484:52-60. [PMID: 21683127 PMCID: PMC3150443 DOI: 10.1016/j.gene.2011.05.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 05/26/2011] [Accepted: 05/30/2011] [Indexed: 01/27/2023]
Abstract
Mitochondrial transcription factor A (Tfam) binds to and organizes mitochondrial DNA (mtDNA) genome into a mitochondrial nucleoid (mt-nucleoid) structure, which is necessary for mtDNA transcription and maintenance. Here, we demonstrate the mtDNA-organizing activity of mouse Tfam and its transcript isoform (Tfam(iso)), which has a smaller high-mobility group (HMG)-box1 domain, using a yeast model system that contains a deletion of the yeast homolog of mouse Tfam protein, Abf2p. When the mouse Tfam genes were introduced into the ABF2 locus of yeast genome, the corresponding mouse proteins, Tfam and Tfam(iso), can functionally replace the yeast Abf2p and support mtDNA maintenance and mitochondrial biogenesis in yeast. Growth properties, mtDNA content and mitochondrial protein levels of genes encoded in the mtDNA were comparable in the strains expressing mouse proteins and the wild-type yeast strain, indicating that the proteins have robust mtDNA-maintaining and -expressing function in yeast mitochondria. These results imply that the mtDNA-organizing activities of the mouse mt-nucleoid proteins are structurally and evolutionary conserved, thus they can maintain the mtDNA of distantly related and distinctively different species, such as yeast.
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Affiliation(s)
- Young Geol Yoon
- Mitochondria Hub Regulation Center and Department of Anatomy and Cell Biology, Dong-A University College of Medicine, Busan 602–714, Republic of Korea
| | - Michael D. Koob
- Institute of Human Genetics and Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN55455, USA
| | - Young Hyun Yoo
- Mitochondria Hub Regulation Center and Department of Anatomy and Cell Biology, Dong-A University College of Medicine, Busan 602–714, Republic of Korea
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15
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Yoon YG, Koob MD, Yoo YH. Re-engineering the mitochondrial genomes in mammalian cells. Anat Cell Biol 2010; 43:97-109. [PMID: 21189990 PMCID: PMC2998782 DOI: 10.5115/acb.2010.43.2.97] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 05/20/2010] [Accepted: 05/25/2010] [Indexed: 02/04/2023] Open
Abstract
Mitochondria are subcellular organelles composed of two discrete membranes in the cytoplasm of eukaryotic cells. They have long been recognized as the generators of energy for the cell and also have been known to associate with several metabolic pathways that are crucial for cellular function. Mitochondria have their own genome, mitochondrial DNA (mtDNA), that is completely separated and independent from the much larger nuclear genome, and even have their own system for making proteins from the genes in this mtDNA genome. The human mtDNA is a small (~16.5 kb) circular DNA and defects in this genome can cause a wide range of inherited human diseases. Despite of the significant advances in discovering the mtDNA defects, however, there are currently no effective therapies for these clinically devastating diseases due to the lack of technology for introducing specific modifications into the mitochondrial genomes and for generating accurate mtDNA disease models. The ability to engineer the mitochondrial genomes would provide a powerful tool to create mutants with which many crucial experiments can be performed in the basic mammalian mitochondrial genetic studies as well as in the treatment of human mtDNA diseases. In this review we summarize the current approaches associated with the correction of mtDNA mutations in cells and describe our own efforts for introducing engineered mtDNA constructs into the mitochondria of living cells through bacterial conjugation.
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Affiliation(s)
- Young Geol Yoon
- Mitochondria Hub Regulation Center and Department of Anatomy and Cell Biology, Dong-A University, Busan, Korea
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16
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Aromolaran KA, Benzow KA, Cribbs LL, Koob MD, Piedras-Rentería ES. T-type current modulation by the actin-binding protein Kelch-like 1. Am J Physiol Cell Physiol 2010; 298:C1353-62. [PMID: 20147652 DOI: 10.1152/ajpcell.00235.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report a novel form of modulation of T-type calcium currents carried out by the neuronal actin-binding protein (ABP) Kelch-like 1 (KLHL1). KLHL1 is a constitutive neuronal ABP localized to the soma and dendritic arbors; its genetic elimination in Purkinje neurons leads to dendritic atrophy and motor insufficiency. KLHL1 participates in neurite outgrowth and upregulates voltage-gated P/Q-type calcium channel function; here we investigated KLHL1's role as a modulator of low-voltage-gated calcium channels and determined the molecular mechanism of this modulation with electrophysiology and biochemistry. Coexpression of KLHL1 with Ca(V)3.1 or Ca(V)3.2 (alpha(1G) or alpha(1H) subunits) caused increases in T-type current density (35%) and calcium influx (75-83%) when carried out by alpha(1H) but not by alpha(1G). The association between KLHL1 and alpha(1H) was determined by immunoprecipitation and immunolocalization in brain membrane fractions and in vitro in HEK-293 cells. Noise analysis showed that neither alpha(1H) single-channel conductance nor open probability was altered by KLHL1, yet a significant increase in channel number was detected and further corroborated by Western blot analysis. KLHL1 also induced an increase in alpha(1H) current deactivation time (tau(deactivation)). Interestingly, the majority of KLHL1's effects were eliminated when the actin-binding motif (kelch) was removed, with the exception of the calcium influx increase during action potentials, indicating that KLHL1 interacts with alpha(1H) and actin and selectively regulates alpha(1H) function by increasing the number of alpha(1H) channels. This constitutes a novel regulatory mechanism of T-type calcium currents and supports the role of KLHL1 in the modulation of cellular excitability.
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Lee JY, Sung BH, Yu BJ, Lee JH, Lee SH, Kim MS, Koob MD, Kim SC. Phenotypic engineering by reprogramming gene transcription using novel artificial transcription factors in Escherichia coli. Nucleic Acids Res 2008; 36:e102. [PMID: 18641039 PMCID: PMC2532725 DOI: 10.1093/nar/gkn449] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Now that many genomes have been sequenced and the products of newly identified genes have been annotated, the next goal is to engineer the desired phenotypes in organisms of interest. For the phenotypic engineering of microorganisms, we have developed novel artificial transcription factors (ATFs) capable of reprogramming innate gene expression circuits in Escherichia coli. These ATFs are composed of zinc finger (ZF) DNA-binding proteins, with distinct specificities, fused to an E. coli cyclic AMP receptor protein (CRP). By randomly assembling 40 different types of ZFs, we have constructed more than 6.4 × 104 ATFs that consist of 3 ZF DNA-binding domains and a CRP effector domain. Using these ATFs, we induced various phenotypic changes in E. coli and selected for industrially important traits, such as resistance to heat shock, osmotic pressure and cold shock. Genes associated with the heat-shock resistance phenotype were then characterized. These results and the general applicability of this platform clearly indicate that novel ATFs are powerful tools for the phenotypic engineering of microorganisms and can facilitate microbial functional genomic studies.
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Affiliation(s)
- Ju Young Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Bong Hyun Sung
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Byung Jo Yu
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jun Hyoung Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Sang Hee Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mi Sun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Michael D. Koob
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Sun Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Biomass Team, Korea Institute of Energy Research, Daejeon, Korea and Department of Laboratory Medicine and Pathology, Institute of Human Genetics, University of Minnesota, Minneapolis, MN 55455, USA
- *To whom correspondence should be addressed. Tel: +82 42 869 2619; Fax: +82 42 869 2610;
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18
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Aromolaran KA, Benzow KA, Koob MD, Piedras-Rentería ES. The Kelch-like protein 1 modulates P/Q-type calcium current density. Neuroscience 2007; 145:841-50. [PMID: 17289272 DOI: 10.1016/j.neuroscience.2006.12.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 12/14/2006] [Accepted: 12/16/2006] [Indexed: 11/21/2022]
Abstract
The actin-binding protein Kelch-like 1 (KLHL1) is a neuronal protein that belongs to the evolutionarily-conserved Kelch protein super-family. The mammalian KLHL1 is brain-specific, cytosolic and can form multimers and bind actin filaments. KLHL1's function is likely that of an actin-organizing protein, possibly modulating neurite outgrowth, the dynamic morphology of dendritic spine heads; or anchoring proteins essential for post-synaptic function, like ion channels. Targeted deletion of the KLHL1 gene in Purkinje neurons results in dendritic deficits in these neurons, abnormal gait, and progressive loss of motor coordination in mice [He Y, Zu T, Benzow KA, Orr HT, Clark HB, Koob MD (2006) Targeted deletion of a single SCA8 ataxia locus allele in mice causes abnormal gait, progressive loss of motor coordination, and Purkinje cell dendritic deficits. J Neurosci 26:9975-9982]. Here we tested the hypothesis that KLHL1 may interact and modulate voltage-gated calcium channels by assessing the interaction of the principal subunit of P/Q-type channels, alpha(1A), with KLHL1. Experiments in human embryonic kidney line HEK 293 (HEK) cells and cerebellar primary cultures revealed co-incidence of alpha(1A) and KLHL1 immunoreactivity when testing both the endogenous or epitope-tagged versions of the proteins. Similarly, co-immunoprecipitation experiments in HEK cells and brain tissue exposed the presence of KLHL1 in protein samples immunoprecipitated with FLAG-tagged or alpha(1A) antibodies. Functional studies of KLHL1 on P/Q-type current properties probed with whole-cell patch clamp revealed a significant increase in mean current density in the presence of KLHL1 (80% increase; from -13.2+/-2.0 pA/pF to -23.7+/-4.2 pA/pF, P<0.02), as well as a shift in steady state activation V(50) of -5.5 mV (from 12.8+/-1.8 mV to 7.3+/-1.0 mV, P<0.02). Our data are consistent with a modulatory effect of KLHL1 on the P/Q-type calcium channel function and suggest a possible novel role for KLHL1 in cellular excitability.
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Affiliation(s)
- K A Aromolaran
- Neuroscience Graduate Program, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
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19
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Yoon YG, Haug CL, Koob MD. Interspecies mitochondrial fusion between mouse and human mitochondria is rapid and efficient. Mitochondrion 2006; 7:223-9. [PMID: 17251069 PMCID: PMC2693707 DOI: 10.1016/j.mito.2006.11.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2006] [Revised: 11/28/2006] [Accepted: 11/30/2006] [Indexed: 10/23/2022]
Abstract
A detailed molecular understanding of mitochondrial fusion and fission in mammalian cells is rapidly emerging. In this report, we demonstrate for the first time cross-species mitochondrial fusion between distantly related species using green and red fluorescent proteins targeted to the mitochondrial matrix. We found that mouse mitochondria were able to efficiently fuse to unmodified mitochondria of human cells and that the contents of the mitochondrial matrix were completely mixed in less than 4h. We also observed that mitochondria from the mtDNA-less (rho(0)) mouse cells can homogeneously fuse to the mitochondria of human cells. We were, however, unable to maintain human mitochondrial DNA in the mouse cells. These results indicate that mitochondrial fusion proteins in mouse and human cells have enough functional homology to mediate efficient cross-species mitochondrial fusion, but mouse nuclear and human mitochondrial genomes have not retained functional compatibility with one another.
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Affiliation(s)
| | | | - Michael D. Koob
- Corresponding author. Tel.: +1 612 626 6516; fax: +1 612 626 7031. E-mail address: (M.D. Koob)
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20
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He Y, Zu T, Benzow KA, Orr HT, Clark HB, Koob MD. Targeted deletion of a single Sca8 ataxia locus allele in mice causes abnormal gait, progressive loss of motor coordination, and Purkinje cell dendritic deficits. J Neurosci 2006; 26:9975-82. [PMID: 17005861 PMCID: PMC6674467 DOI: 10.1523/jneurosci.2595-06.2006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Spinocerebellar ataxia type 8 (SCA8) patients typically have a slowly progressive, adult-onset ataxia. SCA8 is dominantly inherited and is caused by large CTG repeat expansions in the untranslated antisense RNA of the Kelch-like 1 gene (KLHL1), but the molecular mechanism through which this expansion leads to disease is still unknown. To more fully characterize the underlying molecular mechanisms involved in SCA8, we developed a mouse model in which Klhl1 is deleted in either all tissues or is deleted specifically in Purkinje cells only. We found that mice that are either homozygous or heterozygous for the Klhl1 deletion have significant gait abnormalities at an early age and develop a significant loss of motor coordination by 24 weeks of age. This loss progresses more rapidly in homozygous knock-outs. Mice with Klhl1 specifically deleted in only Purkinje cells had a loss of motor coordination that was almost identical to the total-tissue deletion mice. Finally, we found significant Purkinje cell dendritic deficits, as measured by the thickness of the molecular layer, in all mice in which Klhl1 was deleted (both total and Purkinje cell-specific deletions) and an intermediate reduction in molecular layer thickness in mice with reduced levels of Klhl1 expression (heterozygous deletions). The results from this mouse model show that even a partial loss of Klhl1 function leads to degeneration of Purkinje cell function and indicates that loss of KLHL1 activity is likely to play a significant part in the underlying pathophysiology of SCA8.
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Affiliation(s)
- Yungui He
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
| | - Tao Zu
- Institute of Human Genetics
| | - Kellie A. Benzow
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
| | - Harry T. Orr
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
| | - H. Brent Clark
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
- Neurology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Michael D. Koob
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
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21
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Abstract
We have developed a method for transferring exogenous DNA molecules into isolated mammalian mitochondria using bacterial conjugation. In general, we accomplish this by (i) inserting an origin of DNA transfer (oriT) sequence into a DNA construct, (ii) transforming the construct into an appropriate Escherichia coli strain and then (iii) introducing the mobilizable DNA into mitochondria through conjugation. We tested this approach by transferring plasmid DNA containing a T7 promoter sequence into mitochondria that we had engineered to contain T7 RNA polymerase. After conjugation between E.coli and mitochondria, we detected robust levels of T7 transcription from the DNA constructs that had been transferred into the mitochondria. This approach for engineering DNA constructs in vitro and subsequent transfer into mitochondria by conjugation offers an attractive experimental system for studying many aspects of vertebrate mitochondrial gene expression and is a potential route for transforming mitochondrial networks within mammalian cells.
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Affiliation(s)
- Young Geol Yoon
- Department of Laboratory Medicine and Pathology, University of Minnesota420 Delaware Street SE, Minneapolis, MN 55455, USA
- Institute of Human Genetics, University of Minnesota420 Delaware Street SE, Minneapolis, MN 55455, USA
| | - Michael D. Koob
- Department of Laboratory Medicine and Pathology, University of Minnesota420 Delaware Street SE, Minneapolis, MN 55455, USA
- Institute of Human Genetics, University of Minnesota420 Delaware Street SE, Minneapolis, MN 55455, USA
- To whom correspondence should be addressed. Tel: +1 612 626 6516; Fax: +1 612 626 7031;
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22
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Mutsuddi M, Marshall CM, Benzow KA, Koob MD, Rebay I. The Spinocerebellar Ataxia 8 Noncoding RNA Causes Neurodegeneration and Associates with Staufen in Drosophila. Curr Biol 2004; 14:302-8. [PMID: 14972680 DOI: 10.1016/j.cub.2004.01.034] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2003] [Revised: 12/18/2003] [Accepted: 12/29/2003] [Indexed: 11/29/2022]
Abstract
Spinocerebellar Ataxia 8 (SCA8) appears unique among triplet repeat expansion-induced neurodegenerative diseases because the predicted gene product is a noncoding RNA. Little is currently known about the normal function of SCA8 in neuronal survival or how repeat expansion contributes to neurodegeneration. To investigate the molecular context in which SCA8 operates, we have expressed the human SCA8 noncoding RNA in Drosophila. SCA8 induces late-onset, progressive neurodegeneration in the Drosophila retina. Using this neurodegenerative phenotype as a sensitized background for a genetic modifier screen, we have identified mutations in four genes: staufen, muscle-blind, split ends, and CG3249. All four encode neuronally expressed RNA binding proteins conserved in Drosophila and humans. Although expression of both wild-type and repeat-expanded SCA8 induce neurodegeneration, the strength of interaction with certain modifiers differs between the two SCA8 backgrounds, suggesting that CUG expansions alter associations with specific RNA binding proteins. Our demonstration that SCA8 can recruit Staufen and that the interaction domain maps to the portion of the SCA8 RNA that undergoes repeat expansion in the human disease suggests a specific mechanism for SCA8 function and disease. Genetic modifiers identified in our SCA8-based screens may provide candidates for designing therapeutic interventions to treat this disease.
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Affiliation(s)
- Mousumi Mutsuddi
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
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23
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Yoon YG, Koob MD. Efficient cloning and engineering of entire mitochondrial genomes in Escherichia coli and transfer into transcriptionally active mitochondria. Nucleic Acids Res 2003; 31:1407-15. [PMID: 12595548 PMCID: PMC149821 DOI: 10.1093/nar/gkg228] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We have devised an efficient method for replicating and stably maintaining entire mitochondrial genomes in Escherichia coli and have shown that we can engineer these mitochondrial DNA (mtDNA) genome clones using standard molecular biological techniques. In general, we accomplish this by inserting an E.coli replication origin and selectable marker into isolated, circular mtDNA at random locations using an in vitro transposition reaction and then transforming the modified genomes into E.coli. We tested this approach by cloning the 16.3 kb mouse mitochondrial genome and found that the resulting clones could be engineered and faithfully maintained when we used E.coli hosts that replicated them at moderately low copy numbers. When these recombinant mtDNAs were replicated at high copy numbers, however, mtDNA sequences were partially or fully deleted from the original clone. We successfully electroporated recombinant mouse mitochondrial genomes into isolated mouse mitochondria devoid of their own DNA and detected robust in organello RNA synthesis by RT-PCR. This approach for modifying mtDNA and subsequent in organello analysis of the recombinant genomes offers an attractive experimental system for studying many aspects of vertebrate mitochondrial gene expression and is a first step towards true in vivo engineering of mammalian mitochondrial genomes.
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Affiliation(s)
- Young Geol Yoon
- Institute of Human Genetics, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA
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Abstract
Anticipation--earlier onset and more severe disease in the offspring generation--is a well documented feature of familial chronic lymphocytic leukaemia (CLL). In a number of Mendelian diseases, anticipation is caused by expansion of contiguous triplets of nucleotides. The severity of disease expression and penetrance is related to the extent of the triplet expansion. To investigate whether repeat nucleotide repeat expansion is a feature of CLL, the repeat expansion detection (RED) technique was applied to samples from 17 patients with familial disease and 32 patients with early-onset CLL disease. No potentially pathological CAG expansions were detected. We conclude that unstable CAG repeat expansion is not a feature of CLL and that other processes are likely to be involved in generating anticipation in familial forms of the disease.
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Affiliation(s)
- Kellie A Benzow
- Institute of Human Genetics, University of Minnesota, Minneapolis, MN, USA
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25
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Yu BJ, Sung BH, Koob MD, Lee CH, Lee JH, Lee WS, Kim MS, Kim SC. Minimization of the Escherichia coli genome using a Tn5-targeted Cre/loxP excision system. Nat Biotechnol 2002; 20:1018-23. [PMID: 12244329 DOI: 10.1038/nbt740] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2002] [Accepted: 07/15/2002] [Indexed: 11/08/2022]
Abstract
An increasing number of microbial genomes have been completely sequenced, and functional analyses of these genomic sequences are under way. To facilitate these analyses, we have developed a genome-engineering tool for determining essential genes and minimizing bacterial genomes. We made two large pools of independent transposon mutants in Escherichia coli using modified Tn5 transposons with two different selection markers and precisely mapped the chromosomal location of 800 of these transposons. By combining a mapped transposon mutation from each of the mutant pools into the same chromosome using phage P1 transduction and then excising the flanked genomic segment by Cre-mediated loxP recombination, we obtained E. coli strains in which large genomic fragments (59-117 kilobases) were deleted. Some of these individual deletions were then combined into a single "cumulative deletion strain" that lacked 287 open reading frames (313.1 kilobases) but that nevertheless exhibited normal growth under standard laboratory conditions.
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Affiliation(s)
- Byung Jo Yu
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, 305-701, Korea
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26
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Abstract
Spinocerebellar ataxia type 8 (SCA8) is caused by a CTG expansion in an untranslated, endogenous antisense RNA that overlaps the Kelch-like 1 ( KLHL1) gene. The normal function of this transcript is currently unknown. We have now identified the promoter region for the KLHL1-antisense ( KLHL1AS) RNA and report that a Klhl1as transcript is present in the mouse as well. Human and mouse KLHL1AS are transcribed from homologous promoter regions in the first intron of KLHL1 and extend through the transcription and translation start sites as well as the first splice donor sequence of KLHL1. We found that the mouse Klhl1as RNA is not spliced and terminates in a polyadenylation site in the Klhl1 promoter region, whereas both the present and previous work show that human KLHL1AS is highly variably spliced into processed transcripts that contain up to six exons. Mouse Klhl1as transcript was detected in RNA isolated from the cerebellum and from total adult brain and total fetal tissue, and at a low level in testis and ovary. Similarly, human KLHL1AS is expressed in various brain tissues, including the cerebellum, the tissue most affected by SCA8, and was detected at low levels in testis and kidney. The evolutionary conservation of this antisense/sense transcriptional organization strongly indicates that KLHL1AS transcripts play a significant biological role in both human and mouse, presumably as a regulator of KLHL1 expression.
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Affiliation(s)
- Kellie A Benzow
- Institute of Human Genetics, MMC 206 UMHC, 420 Delaware St. SE., University of Minnesota, Minneapolis, Minnesota 55455, USA
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27
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Benzow KA, Koob MD. TheKLHLI-antisense transcript (KLHLIAS) is evolutionarily conserved. Mamm Genome 2002. [DOI: 10.1007/bf02684017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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Moseley ML, Schut LJ, Bird TD, Koob MD, Day JW, Ranum LP. SCA8 CTG repeat: en masse contractions in sperm and intergenerational sequence changes may play a role in reduced penetrance. Hum Mol Genet 2000; 9:2125-30. [PMID: 10958651 DOI: 10.1093/hmg/9.14.2125] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We recently described an untranslated CTG expansion that causes a previously undescribed form of spinocerebellar ataxia (SCA8). The SCA8 CTG repeat is preceded by a polymorphic but stable CTA tract, with the configuration (CTA)(1-21)(CTG)(n). The CTG portion of the repeat is elongated on pathogenic alleles, which nearly always change in size when transmitted from generation to generation. To better understand the reduced penetrance and maternal penetrance bias associated with SCA8 we analyzed the sequence configurations and instability patterns of the CTG repeat in affected and unaffected family members. In contrast to other triplet repeat diseases, expanded alleles found in affected SCA8 individuals can have either a pure uninterrupted CTG repeat tract or an allele with one or more CCG, CTA, CTC, CCA or CTT interruptions. Surprisingly, we found six different sequence configurations of the CTG repeat on expanded alleles in a seven generation family. In two instances duplication of CCG interruptions occurred over a single generation and in other instances duplications that had occurred in different branches of the family could be inferred. We also evaluated SCA8 instability in sperm samples from individuals with expansions ranging in size from 80 to 800 repeats in blood. Surprisingly the SCA8 repeat tract in sperm underwent contractions, with nearly all of the resulting expanded alleles having repeat lengths of <100 CTGs, a size that is not often associated with disease. These en masse repeat contractions in sperm likely underlie the reduced penetrance associated with paternal transmission.
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Affiliation(s)
- M L Moseley
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
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Nemes JP, Benzow KA, Moseley ML, Ranum LP, Koob MD. The SCA8 transcript is an antisense RNA to a brain-specific transcript encoding a novel actin-binding protein (KLHL1). Hum Mol Genet 2000; 9:1543-51. [PMID: 10888605 DOI: 10.1093/hmg/9.10.1543] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spinocerebellar ataxia type 8 (SCA8) is a neurodegenerative disorder caused by the expansion of a CTG trinucleotide repeat that is transcribed as part of an untranslated RNA. As a step towards understanding the molecular pathology of SCA8, we have defined the genomic organization of the SCA8 RNA transcripts and assembled a 166 kb segment of genomic sequence containing the repeat. The most striking feature of the SCA8 transcripts is that the most 5' exon is transcribed through the first exon of another gene that is transcribed in the opposite orientation. This gene arrangement suggests that the SCA8 transcript is an endogenous antisense RNA that overlaps the transcription and translation start sites as well as the first splice donor sequence of the sense gene. The sense transcript encodes a 748 amino acid protein with a predicted domain structure typical of a family of actin-organizing proteins related to the Drosophila Kelch gene, and so has been given the name Kelch-like 1 (KLHL1). We have identified the full-length cDNA sequence for both the human and mouse KLHLI genes, and have elucidated the general genomic organization of the human gene. The predicted open reading frame and promoter region are highly conserved, and both genes are primarily expressed in specific brain tissues, including the cerebellum, the tissue most affected by SCA8. Transfection studies with epitope-tagged KLHL1 demonstrate that the protein localizes to the cytoplasm, suggesting that it may play a role in organizing the actin cytoskeleton of the brain cells in which it is expressed.
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Affiliation(s)
- J P Nemes
- Department of Neurology and Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA
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Abstract
Spinocerebellar ataxia type 7 (SCA7) belongs to a group of neurological disorders caused by a CAG repeat expansion in the coding region of the associated gene. To gain insight into the pathogenesis of SCA7 and possible functions of ataxin-7, we examined the subcellular localization of ataxin-7 in transfected COS-1 cells using SCA7 cDNA clones with different CAG repeat tract lengths. In addition to a diffuse distribution throughout the nucleus, ataxin-7 associated with the nuclear matrix and the nucleolus. The location of the putative SCA7 nuclear localization sequence (NLS) was confirmed by fusing an ataxin-7 fragment with the normally cytoplasmic protein chicken muscle pyruvate kinase. Mutation of this NLS prevented protein from entering the nucleus. Thus, expanded ataxin-7 may carry out its pathogenic effects in the nucleus by altering a matrix-associated nuclear structure and/or by disrupting nucleolar function.
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Affiliation(s)
- M D Kaytor
- Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA
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Koob MD, Moseley ML, Schut LJ, Benzow KA, Bird TD, Day JW, Ranum LP. An untranslated CTG expansion causes a novel form of spinocerebellar ataxia (SCA8). Nat Genet 1999; 21:379-84. [PMID: 10192387 DOI: 10.1038/7710] [Citation(s) in RCA: 464] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Myotonic dystrophy (DM) is the only disease reported to be caused by a CTG expansion. We now report that a non-coding CTG expansion causes a novel form of spinocerebellar ataxia (SCA8). This expansion, located on chromosome 13q21, was isolated directly from the genomic DNA of an ataxia patient by RAPID cloning. SCA8 patients have expansions similar in size (107-127 CTG repeats) to those found among adult-onset DM patients. SCA8 is the first example of a dominant SCA not caused by a CAG expansion translated as a polyglutamine tract.
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Affiliation(s)
- M D Koob
- Department of Neurology, Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA.
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Moseley ML, Benzow KA, Schut LJ, Bird TD, Gomez CM, Barkhaus PE, Blindauer KA, Labuda M, Pandolfo M, Koob MD, Ranum LP. Incidence of dominant spinocerebellar and Friedreich triplet repeats among 361 ataxia families. Neurology 1998; 51:1666-71. [PMID: 9855520 DOI: 10.1212/wnl.51.6.1666] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To determine the incidence of spinocerebellar ataxia (SCA) types 1, 2, 3, 6, and 7 and Friedreich's ataxia (FA) among a large panel of ataxia families. BACKGROUND The ataxias are a clinically and genetically heterogeneous group of neurodegenerative diseases that variably affect the cerebellum, brainstem, and spinocerebellar tracts. Trinucleotide repeat expansions have been shown to be the mutational mechanism for five dominantly inherited SCAs as well as FA. METHODS We collected DNA samples and clinical data from patients representing 361 families with adult-onset ataxia of unknown etiology. Patients with a clinical diagnosis of FA were specifically excluded from our collection. RESULTS Among the 178 dominant kindreds, we found SCA1 expansion at a frequency of 5.6%, SCA2 expansion at a frequency of 15.2%, SCA3 expansion at a frequency of 20.8%, SCA6 expansion at a frequency of 15.2%, and SCA7 expansion at a frequency of 4.5%. FA alleles were found in 11.4% of apparently recessive and 5.2% of apparently sporadic patients. Among these patients the repeat sizes for one or both FA alleles were relatively small, with sizes for the smaller allele ranging from 90 to 600 GAA repeats. The clinical presentation for these patients is atypical for FA, with one or more of the following characteristics: adult onset of disease, retained tendon reflexes, normal plantar response, and intact or partially intact sensory perceptions. CONCLUSIONS Pathogenic trinucleotide repeat expansions were found among 61% of the dominant kindreds. Among patients with apparently recessive or negative family histories of ataxia, 6.8% and 4.4% tested positive for a CAG expansion at one of the dominant loci, and 11.4 and 5.2% of patients with apparently recessive or sporadic forms of ataxia had FA expansions. Because of the significant implications that a dominant versus recessive inheritance pattern has for future generations, it is important to screen patients who do not have a clearly dominant inheritance pattern for expansions at both the FA and the dominant ataxia loci.
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Affiliation(s)
- M L Moseley
- Department of Neurology, University of Minnesota, Minneapolis 55455, USA
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Abstract
We report the mapping of a second myotonic dystrophy locus, myotonic dystrophy type 2 (DM2). Myotonic dystrophy (DM) is a multi-system disease and the most common form of muscular dystrophy in adults. In 1992, DM was shown to be caused by an expanded CTG repeat in the 3' untranslated region of the dystrophia myotonica-protein kinase gene (DMPK) on chromosome 19 (refs 2-6). Although several theories have been put forth to explain how the CTG expansion causes the broad spectrum of clinical features associated with DM, it is not understood how this mutation, which does not alter the protein-coding region of a gene, causes an affect at the cellular level. We have identified a five-generation family (MN1) with a genetically distinct form of myotonic dystrophy. Affected members exhibit remarkable clinical similarity to DM (myotonia, proximal and distal limb weakness, frontal balding, cataracts and cardiac arrhythmias) but do not have the chromosome-19 D CTG expansion. We have mapped the disease locus (DM2) of the MN1 family to a 10-cM region of chromosome 3q. Understanding the common molecular features of two different forms of the disease should shed light on the mechanisms responsible for the broad constellation of seemingly unrelated clinical features present in both diseases.
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Affiliation(s)
- L P Ranum
- Department of Neurology and Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA.
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Abstract
Trinucleotide repeat expansions have been shown to cause a number of neurodegenerative diseases. A hallmark of most of these diseases is the presence of anticipation, a decrease in the age at onset in consecutive generations due to the tendency of the unstable trinucleotide repeat to lengthen when passed from one generation to the next. The involvement of trinucleotide repeat expansions in a number of other diseases--including familial spastic paraplegia, schizophrenia, bipolar affective disorder and spinocerebellar ataxia type 7 (SCA7; ref. 10)--is suggested both by the presence of anticipation and by repeat expansion detection (RED) analysis of genomic DNA samples. The involvement of trinucleotide expansions in these diseases, however, can be conclusively confirmed only by the isolation of the expansions present in these populations and detailed analysis to assess each expansion as a possible pathogenic mutation. We describe a novel procedure for quick isolation of expanded trinucleotide repeats and the corresponding flanking nucleotide sequence directly from small amounts of genomic DNA by a process of Repeat Analysis, Pooled Isolation and Detection of individual clones containing expanded trinucleotide repeats (RAPID cloning). We have used this technique to clone the pathogenic SCA7 CAG expansion from an archived DNA sample of an individual affected with ataxia and retinal degeneration.
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Affiliation(s)
- M D Koob
- Department of Neurology, University of Minnesota, Minneapolis 55455, USA.
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Pósfai G, Koob MD, Kirkpatrick HA, Blattner FR. Versatile insertion plasmids for targeted genome manipulations in bacteria: isolation, deletion, and rescue of the pathogenicity island LEE of the Escherichia coli O157:H7 genome. J Bacteriol 1997; 179:4426-8. [PMID: 9209066 PMCID: PMC179272 DOI: 10.1128/jb.179.13.4426-4428.1997] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A system of versatile insertion plasmids was constructed that permits efficient delivery of the target sites of an ultra-rare-cutting endonuclease and the recombinase FLP into preselected sites of the bacterial genome. With the help of this system, the pathogenicity island LEE of the Escherichia coli O157:H7 genome was excised and isolated in vitro, deleted in vivo, rescued as a plasmid, and transferred into another strain.
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Affiliation(s)
- G Pósfai
- Institute of Biochemistry, Biological Research Center, Szeged, Hungary.
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Affiliation(s)
- M D Koob
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison 53706
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Hauser MA, Koob MD, Roth JA. Variation of neutrophil function with age in calves. Am J Vet Res 1986; 47:152-3. [PMID: 3946895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Neutrophil function was evaluated on 2 occasions in 5 calves from each of the following age groups: 4 to 5 weeks, 9 to 11 weeks, 16 to 19 weeks, and 12 to 14 months. Of the neutrophil functions examined, the iodination reaction, which evaluates the activity of the myeloperoxidase-hydrogen peroxide-halide antibacterial system of the neutrophil, reflected the most marked differences among age groups. The iodination values for the 2 youngest age groups were approximately 52% of the value for the oldest cattle. This difference could not be attributed to the amount of myeloperoxidase in the neutrophil granules. Antibody-dependent cell-mediated cytotoxicity also tended to be lower in neutrophils from the 3 younger age groups. Nitroblue tetrazolium reduction, a measure of superoxide anion generation by neutrophils, was lower in the youngest age group only. The capability of neutrophils to ingest Staphylococcus aureus was higher in the 3 youngest groups of calves than in the oldest group. The observed differences in neutrophil function in young vs older calves may be partially responsible for the increased susceptibility of young calves to infectious disease.
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