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Pressman PS, Carter DJ, Ramos EM, Molden J, Smith K, Dino F, McMillan C, Irwin D, Rascovsky K, Ghoshal N, Knudtson M, Rademakers R, Geschwind D, Gendron T, Petrucelli L, Heuer H, Boeve BF, Barmada S, Boxer A, Tempini MLG, Rosen HJ. Symptomatic progression of frontotemporal dementia with the TARDBP I383V variant. Neurocase 2024:1-9. [PMID: 38757415 DOI: 10.1080/13554794.2024.2354540] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
We present a longitudinal description of a man with the TARDBP I383V variant of frontotemporal dementia (FTD). His progressive changes in behavior and language resulted in a diagnosis of the right temporal variant of FTD, also called the semantic behavioral variant (sbvFTD). We also present data from a small series of patients with the TARDBP I383V variant who were enrolled in a nationwide FTD research collaboration (ALLFTD). These data support slowly progressive loss of semantic function. While semantic dementia is infrequently considered genetic, the TARDBP I383V variant seems to be an exception. Longitudinal analyses in larger samples are warranted.
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Affiliation(s)
- Peter S Pressman
- Alzheimer and Cognition Center, University of Colorado, Aurora, CO, US
| | - Danelle J Carter
- Alzheimer and Cognition Center, University of Colorado, Aurora, CO, US
| | - Eliana Marisa Ramos
- Department of Neurology, Anschutz Medical Campus, School of Medicine, University of California, Los Angeles, CA, US
| | - Joie Molden
- Department of Neurosurgery, University of Colorado, Boulder, CO, US
| | - Kaitlin Smith
- Alzheimer and Cognition Center, University of Colorado, Aurora, CO, US
| | - Francesca Dino
- Alzheimer and Cognition Center, University of Colorado, Aurora, CO, US
| | - Corey McMillan
- Penn Frontotemporal Degeneration Center, University of Pennsylvania, Philadelphia, PA, US
| | - David Irwin
- Penn Frontotemporal Degeneration Center, University of Pennsylvania, Philadelphia, PA, US
| | - Katya Rascovsky
- Penn Frontotemporal Degeneration Center, University of Pennsylvania, Philadelphia, PA, US
| | - Nupur Ghoshal
- Departments of Neurology and Psychiatry, Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Rosa Rademakers
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, US
| | - Daniel Geschwind
- Division of Behavioral Neurology, Mayo Clinic College Rochester, Rochester, MN, USA
| | - Tania Gendron
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, US
| | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, US
| | - Hilary Heuer
- Memory and Aging Center, University of California, San Francisco, CA, USA
| | - Bradley F Boeve
- Department of Neuroscience, Mayo Clinic Jacksonville, Jacksonville, FL, US
| | - Sami Barmada
- Division of Behavioral Neurology, Mayo Clinic College Rochester, Rochester, MN, USA
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Adam Boxer
- Memory and Aging Center, University of California, San Francisco, CA, USA
| | | | - Howard J Rosen
- Memory and Aging Center, University of California, San Francisco, CA, USA
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Pressman PS, Molden J, Wortzel HS, Plys E, Woodcock JH, Filley CM, Arciniegas DB. Psychiatric Screening Measures in Behavioral Variant Frontotemporal Dementia. J Neuropsychiatry Clin Neurosci 2023; 36:160-165. [PMID: 37981780 DOI: 10.1176/appi.neuropsych.20230041] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
OBJECTIVE Behavioral variant frontotemporal dementia (bvFTD) is sometimes misdiagnosed as a primary psychiatric disorder, such as major depressive disorder, bipolar disorder, an anxiety disorder, autism spectrum disorder (ASD), or attention-deficit hyperactivity disorder (ADHD). Nonspecialists often use screening measures for primary psychiatric disorders in early assessments of persons with bvFTD. The investigators aimed to evaluate the manifestations of bvFTD in surveys intended to screen for primary psychiatric disorders. METHODS Patients with bvFTD (N=27) presenting to an academic neurobehavior specialty clinic and their caregivers were provided questionnaire packets including the Mood Disorder Questionnaire (MDQ), the Patient Health Questionnaire-9 (PHQ-9), the Generalized Anxiety Disorder-7 scale (GAD-7), the Adult ADHD Self-Report Scale, version 1.1, the Ritvo Autism and Asperger Diagnostic Scale, and the Neuropsychiatric Inventory Questionnaire. Established cutoff scores suggesting the presence of a primary psychiatric disorder were used to define a "positive" response. Individual questions from each screening questionnaire were examined for a more granular characterization of bvFTD. RESULTS Overall, 15% of bvFTD patients screened positive for bipolar disorder, 54% screened positive for ADHD, and 89% screened positive for ASD. Hyperactivity or hypersensitivity symptoms were infrequently endorsed. In addition, 57% of respondents screened positive for depressive symptoms on the PHQ-9, and 43% screened positive for anxiety symptoms on the GAD-7. CONCLUSIONS The use of cutoff scores on screening measures for primary psychiatric disorders resulted in potentially problematic positive screens of primary psychiatric disorders among persons with bvFTD. Identifying specific questions that distinguish between bvFTD and primary psychiatric disorders requires further study.
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Affiliation(s)
- Peter S Pressman
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
| | - Joie Molden
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
| | - Hal S Wortzel
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
| | - Evan Plys
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
| | - Jonathan H Woodcock
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
| | - Christopher M Filley
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
| | - David B Arciniegas
- Behavioral Neurology Section, Department of Neurology (Pressman, Wortzel, Woodcock, Filley, Arciniegas), and Department of Psychiatry (Wortzel, Filley, Arciniegas), University of Colorado School of Medicine, Aurora; Departments of Neurosurgery (Molden) and Psychiatry (Plys) and the Marcus Institute for Brain Health (Filley, Arciniegas), University of Colorado Anschutz Medical Campus, Aurora; Rocky Mountain Mental Illness Research, Education, and Clinical Center for Suicide Prevention, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora (Wortzel); Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque (Arciniegas)
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Molden J, Plys E, Williams K, Nichols C, Eades A, Engleman L, Qualls S, Segal D. THE HEALTHY LIVING PROJECT: AN INTERDISCIPLINARY WELLNESS PROGRAM FOR OLDER ADULTS. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.2982] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J. Molden
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - E. Plys
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - K. Williams
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - C. Nichols
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - A. Eades
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - L. Engleman
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - S.H. Qualls
- University of Colorado Colorado Springs, Colorado Springs, Colorado
| | - D.L. Segal
- University of Colorado Colorado Springs, Colorado Springs, Colorado
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Molden J, Maxfield M. A-19The Effect of Mixed Aging Stereotype Priming on Older Adults’ Memory Performance. Arch Clin Neuropsychol 2016. [DOI: 10.1093/arclin/acw043.19] [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: 11/14/2022] Open
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Abstract
Dementia worry, an anxiety-related response to the possibility of developing dementia, represents an important yet underexplored health concern for an aging population. Such a construct is likely impacted by stereotypes concerning aging, including biased associations of aging with inevitable cognitive decline. The present article explores the impact of mixed positive and negative aging stereotype messages on levels of dementia worry. The Fear of Alzheimer's Disease Scale (FADS) was used to measure impact of priming with different proportions of positive and negative aging stereotype words. The priming intervention was modeled after Levy (J Pers Soc Psychol 71:1092-1107, 1996, doi:10.1037/0022-3514.71.6.1092). Eighty older adult participants (Mage = 71.65, SD = 6.57) were exposed to mostly positive aging stereotype words, half positive/half negative words, mostly negative words, all negative words, or non-stereotype words. Mean FADS item response was significantly impacted by priming such that those in the all negative condition had highest levels of dementia worry, F(4, 75) = 2.48, p = .05, [Formula: see text]. This effect was strengthened when relevance of aging stereotypes was controlled for, p < .01. Results suggested that brief exposure to negative aging stereotype content increased levels of dementia worry, particularly when stereotypes were self-relevant. These findings indicate addressing aging stereotypes may be one way of impacting dementia worry.
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Affiliation(s)
- Joie Molden
- Department of Psychology, University of Colorado Colorado Springs, Colorado Springs, CO 80918 USA
| | - Molly Maxfield
- Department of Psychology, University of Colorado Colorado Springs, Colorado Springs, CO 80918 USA
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Abstract
Dementia worry, an anxiety-related response to the possibility of developing dementia, represents an important yet underexplored health concern for an aging population. Such a construct is likely impacted by stereotypes concerning aging, including biased associations of aging with inevitable cognitive decline. The present article explores the impact of mixed positive and negative aging stereotype messages on levels of dementia worry. The Fear of Alzheimer's Disease Scale (FADS) was used to measure impact of priming with different proportions of positive and negative aging stereotype words. The priming intervention was modeled after Levy (J Pers Soc Psychol 71:1092-1107, 1996, doi:10.1037/0022-3514.71.6.1092). Eighty older adult participants (Mage = 71.65, SD = 6.57) were exposed to mostly positive aging stereotype words, half positive/half negative words, mostly negative words, all negative words, or non-stereotype words. Mean FADS item response was significantly impacted by priming such that those in the all negative condition had highest levels of dementia worry, F(4, 75) = 2.48, p = .05, [Formula: see text]. This effect was strengthened when relevance of aging stereotypes was controlled for, p < .01. Results suggested that brief exposure to negative aging stereotype content increased levels of dementia worry, particularly when stereotypes were self-relevant. These findings indicate addressing aging stereotypes may be one way of impacting dementia worry.
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Affiliation(s)
- Joie Molden
- Department of Psychology, University of Colorado Colorado Springs, Colorado Springs, CO 80918 USA
| | - Molly Maxfield
- Department of Psychology, University of Colorado Colorado Springs, Colorado Springs, CO 80918 USA
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Molden J, Maxfield M, Gavett BE. P3‐274: Dementia worry among a sample of older adults seeking memory screening. Alzheimers Dement 2015. [DOI: 10.1016/j.jalz.2015.06.1647] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Joie Molden
- University of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Molly Maxfield
- University of Colorado Colorado SpringsColorado SpringsCOUSA
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Molden J, Renn BN, Gurnani AS, Nicoll T, Tyrrell C, Luther EC, Gavett BE. P4‐107: Feasibility and outcomes of a national memory screening day at a community senior mental health clinic. Alzheimers Dement 2015. [DOI: 10.1016/j.jalz.2015.06.1813] [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: 11/25/2022]
Affiliation(s)
- Joie Molden
- University of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Brenna N. Renn
- University of Colorado Colorado SpringsColorado SpringsCOUSA
| | | | - Tracie Nicoll
- University of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Caitlin Tyrrell
- University of Colorado Colorado SpringsColorado SpringsCOUSA
| | - Emily C. Luther
- University of Colorado Colorado SpringsColorado SpringsCOUSA
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O'Brien TR, Kedes D, Ganem D, Macrae DR, Rosenberg PS, Molden J, Goedert JJ. Evidence for concurrent epidemics of human herpesvirus 8 and human immunodeficiency virus type 1 in US homosexual men: rates, risk factors, and relationship to Kaposi's sarcoma. J Infect Dis 1999; 180:1010-7. [PMID: 10479125 DOI: 10.1086/315039] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
We examined human herpesvirus 8 (HHV-8) seroprevalence and seroincidence among 245 homosexual men from New York City (NYC) and Washington, DC (DC) who have been followed since 1982. An immunofluorescence assay measured antibodies to a latent HHV-8 nuclear antigen. Seroprevalence was 20.4% in 1982; seroincidence was approximately 15%/year during 1982-1983 but fell sharply thereafter. NYC men had a higher seroprevalence (odds ratio, 3.43; P<.001) and seroincidence (rate ratio, 2.13; P=.01) than DC men. Risk of Kaposi's sarcoma (KS) was increased in seropositive men (adjusted relative hazard, 3.58; P=.02). Among men who were seropositive for both human immunodeficiency virus type 1 and HHV-8, the 10-year cumulative risk of KS was 39%; time from coinfection to KS diagnosis ranged from 15 to 154 months (median, 63.5 months). This study shows an epidemic of HHV-8 among US homosexual men in the early 1980s that was associated with a high risk of developing KS.
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Affiliation(s)
- T R O'Brien
- Viral Epidemiology Branch, National Cancer Institute, EPS 8016, Rockville, MD 20852, USA.
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Longmore GD, You Y, Molden J, Liu KD, Mikami A, Lai SY, Pharr P, Goldsmith MA. Redundant and selective roles for erythropoietin receptor tyrosines in erythropoiesis in vivo. Blood 1998; 91:870-8. [PMID: 9446647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cytokine receptors have been shown in cell culture systems to use phosphotyrosine residues as docking sites for certain signal transduction intermediates. Studies using various cellular backgrounds have yielded conflicting information about the importance of such residues. The present studies were undertaken to determine whether or not tyrosine residues within the erythropoietin receptor (EPOR) are essential for biologic activity during hematopoiesis in vivo. A variant of the EPOR was constructed that contains both a substitution (R129C) causing constitutive receptor activation as well as replacement of all eight cytoplasmic tyrosines by phenylalanines (cEPORYF). A comparison between animals exposed to recombinant retroviruses expressing cEPOR and cEPORYF showed that efficient red blood cell (RBC) development in vivo is dependent on the pressence of tyrosine residues in the cytoplasmic domain of the EPOR. In addition, an inefficient EPOR tyrosine independent pathway supporting RBC development was detected. Tyrosine add-back mutants showed that multiple individual tyrosines have the capacity to restore full erythropoietic potential to the EPOR as determined in whole animals. The analysis of primary erythroid progenitors transduced with the various cEPOR tyrosine mutants and tyrosine add-backs showed that only tyrosine 343 (Y1) and tyrosine 479 (Y8) were capable of supporting immature burst-forming unit-erythroid progenitor development. Thus, this receptor is characterized by striking functional redundancy of tyrosines in a biologically relevant context. However, selective tyrosine residues may be uniquely important for early signals supporting erythroid development.
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Affiliation(s)
- G D Longmore
- Department of Medicine, Washington University School of Medicine, St Louis, MO, USA
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Molden J, Chang Y, You Y, Moore PS, Goldsmith MA. A Kaposi's sarcoma-associated herpesvirus-encoded cytokine homolog (vIL-6) activates signaling through the shared gp130 receptor subunit. J Biol Chem 1997; 272:19625-31. [PMID: 9235971 DOI: 10.1074/jbc.272.31.19625] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.4] [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
The present studies analyzed the biologic activity of a gene product (vIL-6) encoded by the recently discovered Kaposi's sarcoma-associated herpesvirus (KSHV) bearing 24.8% amino acid identity with human interleukin-6 (huIL-6). Based on this similarity, we hypothesized that this viral homolog might trigger the JAK/STAT pathway, which typically is engaged by IL-6 and other cytokines. Activation of receptor-associated Janus tyrosine kinases (JAKs) results in the subsequent phosphorylation of signal transducers and activators of transcription (STATs) leading to nuclear entry and transcriptional regulation of target genes. Treatment of HepG2 cells with culture medium containing recombinant KSHV-encoded vIL-6 led to rapid induction of JAK1 phosphorylation and a nuclear DNA-binding activity found to contain STAT1 and STAT3. An antibody to the IL-6 receptor (IL-6R) alpha subunit effectively neutralized the response to huIL-6 but failed to block STAT activation by vIL-6. In contrast, an antibody reactive with the gp130 subunit of IL-6R abrogated signaling of both responses. Moreover, a transfected cell line expressing human gp130 without IL-6Ralpha exhibited a robust response to vIL-6 but not to huIL-6. These results demonstrate that KSHV encodes a cytokine that activates specific JAK/STAT signaling via interactions with the gp130 signal transducing subunit independently of the IL-6Ralpha chain. This activity may have an impact on gp130-mediated signaling in response to native cytokines and thereby influence disease pathogenesis upon KSHV infection.
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Affiliation(s)
- J Molden
- Gladstone Institute of Virology and Immunology, San Francisco, California 94141-9100, USA
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Lai SY, Molden J, Goldsmith MA. Shared gamma(c) subunit within the human interleukin-7 receptor complex. A molecular basis for the pathogenesis of X-linked severe combined immunodeficiency. J Clin Invest 1997; 99:169-77. [PMID: 9005984 PMCID: PMC507783 DOI: 10.1172/jci119144] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [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: 02/03/2023] Open
Abstract
Genetic evidence suggests that mutations in the gamma(c) receptor subunit cause X-linked severe combined immunodeficiency (X-SCID). The gamma(c) subunit can be employed in receptor complexes for IL-2, -4, -7, -9, and -15, and the multiple signaling defects that would result from a defective gamma(c) chain in these receptors are proposed to cause the severe phenotype of X-SCID patients. Interestingly, gene disruption of either IL-7 or the IL-7 receptor (IL-7R) alpha subunit in mice leads to immunological defects that are similar to human X-SCID. These observations suggest the functional importance of gamma(c) in the IL-7R complex. In the present study, structure/function analyses of the IL-7R complex using a chimeric receptor system demonstrated that gamma(c) is indeed critical for IL-7R function. Nonetheless, only a limited portion of the cytoplasmic domain of gamma(c) is necessary for IL-7R signal transduction. Furthermore, replacement of the gamma(c) cytoplasmic domain by a severely truncated erythropoeitin receptor does not affect measured IL-7R signaling events. These findings support a model in which gamma(c) serves primarily to activate signal transduction by the IL-7R complex, while IL-7R alpha determines specific signaling events through its association with cytoplasmic signaling molecules. Finally, these studies are consistent with the hypothesis that the molecular pathogenesis of X-SCID is due primarily to gamma(c)-mediated defects in the IL-7/IL-7R system.
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Affiliation(s)
- S Y Lai
- Gladstone Institute of Virology and Immunology, San Francisco, California 94141-9100, USA
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Lai SY, Molden J, Liu KD, Puck JM, White MD, Goldsmith MA. Interleukin-4-specific signal transduction events are driven by homotypic interactions of the interleukin-4 receptor alpha subunit. EMBO J 1996; 15:4506-14. [PMID: 8887542 PMCID: PMC452180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Interleukin-4 (IL-4) exerts its effects through a heterodimeric receptor complex (IL-4R), which contains the IL-4R(alpha) and gamma(c) subunits. IL-4R(alpha) also functions with other partner subunits in several receptor types, including the IL-13 receptor. To examine the roles of the individual subunits within IL-4R complexes, we employed a chimeric system that recapitulates native IL-4R function as verified by the activation of the kinases, JAK1 and JAK3, and induction of STAT-6. When a mutant gamma(c) subunit in which the four cytoplasmic tyrosines were converted to phenylalanine was paired with the cytoplasmic domain of the IL-4R(alpha) chain, specificity within the JAK-STAT pathway was not altered. Signaling events were examined further in cells expressing the IL-4R(alpha) chimera alone without the gamma(c) chimera. Ligand-induced homodimerization of these receptors activated the IL-4 signaling program despite the absence of gamma(c), including induction of JAK1 and STAT-6, phosphorylation of the insulin-related substrate 1 and cellular proliferation. Thus, homotypic interactions of the IL-4R(alpha) subunit are sufficient for the initiation and determination of IL-4-specific signaling events, and such interactions may be integral to signaling through IL-4R complexes.
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Affiliation(s)
- S Y Lai
- Gladstone Institute of Virology and Immunology, University of California, San Francisco, USA
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Lai SY, Molden J, Liu KD, Puck JM, White MD, Goldsmith MA. Interleukin-4-specific signal transduction events are driven by homotypic interactions of the interleukin-4 receptor alpha subunit. EMBO J 1996. [DOI: 10.1002/j.1460-2075.1996.tb00828.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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