1
|
A Novel Cis-Regulatory lncRNA, Kalnc2, Downregulates Kalrn Protein-Coding Transcripts in Mouse Neuronal Cells. Noncoding RNA 2023; 9:ncrna9010007. [PMID: 36649036 PMCID: PMC9844340 DOI: 10.3390/ncrna9010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/29/2022] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
The KALRN gene encodes several multi-domain protein isoforms that localize to neuronal synapses, conferring the ability to grow and retract dendritic spines and shaping axonal outgrowth, dendrite morphology, and dendritic spine re-modeling. The KALRN genomic locus is implicated in several neurodevelopmental and neuropsychiatric diseases, including autism, schizophrenia, bipolar disease, and intellectual disability. We have previously shown that a novel brain-specific long non-coding RNA (lncRNA) arising from the 5' end of the kalrna gene, called durga, regulates neuronal morphology in zebrafish. Here, we characterized mammalian Kalrn loci, annotating and experimentally validating multiple novel non-coding RNAs, including linear and circular variants. Comparing the mouse and human loci, we show that certain non-coding RNAs and Kalrn protein-coding isoforms arising from the locus show similar expression dynamics during development. In humans, mice, and zebrafish, the 5' end of the Kalrn locus gives rise to a chromatin-associated lncRNA that is present in adult ovaries, besides being expressed during brain development and enriched in certain regions of the adult brain. Ectopic expression of this lncRNA led to the downregulation of all the major Kalrn mRNA isoforms. We propose that this lncRNA arising from the 5' end of the Kalrn locus is functionally the mammalian ortholog of zebrafish lncRNA durga.
Collapse
|
2
|
Grubisha MJ, DeGiosio RA, Wills ZP, Sweet RA. Trio and Kalirin as unique enactors of Rho/Rac spatiotemporal precision. Cell Signal 2022; 98:110416. [PMID: 35872089 DOI: 10.1016/j.cellsig.2022.110416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 12/18/2022]
Abstract
Rac1 and RhoA are among the most widely studied small GTPases. The classic dogma surrounding their biology has largely focused on their activity as an "on/off switch" of sorts. However, the advent of more sophisticated techniques, such as genetically-encoded FRET-based sensors, has afforded the ability to delineate the spatiotemporal regulation of Rac1 and RhoA. As a result, there has been a shift from this simplistic global view to one incorporating the precision of spatiotemporal modularity. This review summarizes emerging data surrounding the roles of Rac1 and RhoA as cytoskeletal regulators and examines how these new data have led to a revision of the traditional dogma which placed Rac1 and RhoA in antagonistic pathways. This more recent evidence suggests that rather than absolute activity levels, it is the tight spatiotemporal regulation of Rac1 and RhoA across multiple roles, from oppositional to complementary, that is necessary to execute coordinated cytoskeletal processes affecting cell structure, function, and migration. We focus on how Kalirin and Trio, as dual GEFs that target Rac1 and RhoA, are uniquely designed to provide the spatiotemporally-precise shifts in Rac/Rho balance which mediate changes in neuronal structure and function, particularly by way of cytoskeletal rearrangements. Finally, we review how alterations in Trio and/or Kalirin function are associated with cellular abnormalities and neuropsychiatric disease.
Collapse
Affiliation(s)
- M J Grubisha
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - R A DeGiosio
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Z P Wills
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - R A Sweet
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
3
|
Mould AW, Hall NA, Milosevic I, Tunbridge EM. Targeting synaptic plasticity in schizophrenia: insights from genomic studies. Trends Mol Med 2021; 27:1022-1032. [PMID: 34419330 DOI: 10.1016/j.molmed.2021.07.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 12/12/2022]
Abstract
Patients with schizophrenia experience cognitive dysfunction and negative symptoms that do not respond to current drug treatments. Historical evidence is consistent with the hypothesis that these deficits are due, at least in part, to altered cortical synaptic plasticity (the ability of synapses to strengthen or weaken their activity), making this an attractive pathway for therapeutic intervention. However, while synaptic transmission and plasticity is well understood in model systems, it has been challenging to identify specific therapeutic targets for schizophrenia. New information is emerging from genomic findings, which converge on synaptic plasticity and provide a new window on the neurobiology of schizophrenia. Translating this information into therapeutic advances will require a multidisciplinary and collaborative approach.
Collapse
Affiliation(s)
- Arne W Mould
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, UK
| | - Nicola A Hall
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, UK
| | - Ira Milosevic
- Wellcome Centre for Human Genetics, Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK; Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Elizabeth M Tunbridge
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health NHS Foundation Trust, Oxford, UK.
| |
Collapse
|
4
|
Bäck N, Mains RE, Eipper BA. PAM: diverse roles in neuroendocrine cells, cardiomyocytes, and green algae. FEBS J 2021; 289:4470-4496. [PMID: 34089560 DOI: 10.1111/febs.16049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/28/2021] [Accepted: 06/02/2021] [Indexed: 12/13/2022]
Abstract
Our understanding of the ways in which peptides are used for communication in the nervous and endocrine systems began with the identification of oxytocin, vasopressin, and insulin, each of which is stored in electron-dense granules, ready for release in response to an appropriate stimulus. For each of these peptides, entry of its newly synthesized precursor into the ER lumen is followed by transport through the secretory pathway, exposing the precursor to a sequence of environments and enzymes that produce the bioactive products stored in mature granules. A final step in the biosynthesis of many peptides is C-terminal amidation by peptidylglycine α-amidating monooxygenase (PAM), an ascorbate- and copper-dependent membrane enzyme that enters secretory granules along with its soluble substrates. Biochemical and cell biological studies elucidated the highly conserved mechanism for amidated peptide production and raised many questions about PAM trafficking and the effects of PAM on cytoskeletal organization and gene expression. Phylogenetic studies and the discovery of active PAM in the ciliary membranes of Chlamydomonas reinhardtii, a green alga lacking secretory granules, suggested that a PAM-like enzyme was present in the last eukaryotic common ancestor. While the catalytic features of human and C. reinhardtii PAM are strikingly similar, the trafficking of PAM in C. reinhardtii and neuroendocrine cells and secretion of its amidated products differ. A comparison of PAM function in neuroendocrine cells, atrial myocytes, and C. reinhardtii reveals multiple ways in which altered trafficking allows PAM to accomplish different tasks in different species and cell types.
Collapse
Affiliation(s)
- Nils Bäck
- Department of Anatomy, University of Helsinki, Finland
| | - Richard E Mains
- Department of Neuroscience, UConn Health, Farmington, CT, USA
| | - Betty A Eipper
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
| |
Collapse
|
5
|
Machin PA, Tsonou E, Hornigold DC, Welch HCE. Rho Family GTPases and Rho GEFs in Glucose Homeostasis. Cells 2021; 10:cells10040915. [PMID: 33923452 PMCID: PMC8074089 DOI: 10.3390/cells10040915] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/11/2021] [Accepted: 04/13/2021] [Indexed: 12/17/2022] Open
Abstract
Dysregulation of glucose homeostasis leading to metabolic syndrome and type 2 diabetes is the cause of an increasing world health crisis. New intriguing roles have emerged for Rho family GTPases and their Rho guanine nucleotide exchange factor (GEF) activators in the regulation of glucose homeostasis. This review summates the current knowledge, focusing in particular on the roles of Rho GEFs in the processes of glucose-stimulated insulin secretion by pancreatic β cells and insulin-stimulated glucose uptake into skeletal muscle and adipose tissues. We discuss the ten Rho GEFs that are known so far to regulate glucose homeostasis, nine of which are in mammals, and one is in yeast. Among the mammalian Rho GEFs, P-Rex1, Vav2, Vav3, Tiam1, Kalirin and Plekhg4 were shown to mediate the insulin-stimulated translocation of the glucose transporter GLUT4 to the plasma membrane and/or insulin-stimulated glucose uptake in skeletal muscle or adipose tissue. The Rho GEFs P-Rex1, Vav2, Tiam1 and β-PIX were found to control the glucose-stimulated release of insulin by pancreatic β cells. In vivo studies demonstrated the involvement of the Rho GEFs P-Rex2, Vav2, Vav3 and PDZ-RhoGEF in glucose tolerance and/or insulin sensitivity, with deletion of these GEFs either contributing to the development of metabolic syndrome or protecting from it. This research is in its infancy. Considering that over 80 Rho GEFs exist, it is likely that future research will identify more roles for Rho GEFs in glucose homeostasis.
Collapse
Affiliation(s)
- Polly A. Machin
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; (P.A.M.); (E.T.)
| | - Elpida Tsonou
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; (P.A.M.); (E.T.)
- Bioscience Metabolism, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Cambridge CB22 3AT, UK;
| | - David C. Hornigold
- Bioscience Metabolism, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Cambridge CB22 3AT, UK;
| | - Heidi C. E. Welch
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; (P.A.M.); (E.T.)
- Correspondence: ; Tel.: +44-(0)1223-496-596
| |
Collapse
|
6
|
Bircher JE, Koleske AJ. Trio family proteins as regulators of cell migration and morphogenesis in development and disease - mechanisms and cellular contexts. J Cell Sci 2021; 134:jcs248393. [PMID: 33568469 PMCID: PMC7888718 DOI: 10.1242/jcs.248393] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The well-studied members of the Trio family of proteins are Trio and kalirin in vertebrates, UNC-73 in Caenorhabditis elegans and Trio in Drosophila Trio proteins are key regulators of cell morphogenesis and migration, tissue organization, and secretion and protein trafficking in many biological contexts. Recent discoveries have linked Trio and kalirin to human disease, including neurological disorders and cancer. The genes for Trio family proteins encode a series of large multidomain proteins with up to three catalytic activities and multiple scaffolding and protein-protein interaction domains. As such, Trio family proteins engage a wide array of cell surface receptors, substrates and interaction partners to coordinate changes in cytoskeletal regulatory and protein trafficking pathways. We provide a comprehensive review of the specific mechanisms by which Trio family proteins carry out their functions in cells, highlight the biological and cellular contexts in which they occur, and relate how alterations in these functions contribute to human disease.
Collapse
Affiliation(s)
- Josie E Bircher
- Department of Molecular Biochemistry and Biophysics, Yale School of Medicine, Yale University, New Haven, CT 06511 USA
| | - Anthony J Koleske
- Department of Molecular Biochemistry and Biophysics, Yale School of Medicine, Yale University, New Haven, CT 06511 USA
| |
Collapse
|
7
|
Parnell E, Shapiro LP, Voorn RA, Forrest MP, Jalloul HA, Loizzo DD, Penzes P. KALRN: A central regulator of synaptic function and synaptopathies. Gene 2020; 768:145306. [PMID: 33189799 DOI: 10.1016/j.gene.2020.145306] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/28/2020] [Accepted: 11/06/2020] [Indexed: 12/23/2022]
Abstract
The synaptic regulator, kalirin, plays a key role in synaptic plasticity and formation of dendritic arbors and spines. Dysregulation of the KALRN gene has been linked to various neurological disorders, including autism spectrum disorder, Alzheimer's disease, schizophrenia, addiction and intellectual disabilities. Both genetic and molecular studies highlight the importance of normal KALRN expression for healthy neurodevelopment and function. This review aims to give an in-depth analysis of the structure and molecular mechanisms of kalirin function, particularly within the brain. These data are correlated to genetic evidence of patient mutations within KALRN and animal models of Kalrn that together give insight into the manner in which this gene may be involved in neurodevelopment and the etiology of disease. The emerging links to human disease from post-mortem, genome wide association (GWAS) and exome sequencing studies are examined to highlight the disease relevance of kalirin, particularly in neurodevelopmental diseases. Finally, we will discuss efforts to pharmacologically regulate kalirin protein activity and the implications of such endeavors for the treatment of human disease. As multiple disease states arise from deregulated synapse formation and altered KALRN expression and function, therapeutics may be developed to provide control over KALRN activity and thus synapse dysregulation. As such, a detailed understanding of how kalirin regulates neuronal development, and the manner in which kalirin dysfunction promotes neurological disease, may support KALRN as a valuable therapeutic avenue for future pharmacological intervention.
Collapse
Affiliation(s)
- Euan Parnell
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA
| | - Lauren P Shapiro
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA
| | - Roos A Voorn
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA
| | - Marc P Forrest
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA
| | - Hiba A Jalloul
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA
| | - Daniel D Loizzo
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA
| | - Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA; Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, 60611 IL, USA; Northwestern University Center for Autism and Neurodevelopment, Chicago, IL 60611, USA.
| |
Collapse
|
8
|
Kotelevets L, Chastre E. Rac1 Signaling: From Intestinal Homeostasis to Colorectal Cancer Metastasis. Cancers (Basel) 2020; 12:cancers12030665. [PMID: 32178475 PMCID: PMC7140047 DOI: 10.3390/cancers12030665] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/06/2020] [Accepted: 03/08/2020] [Indexed: 12/14/2022] Open
Abstract
The small GTPase Rac1 has been implicated in a variety of dynamic cell biological processes, including cell proliferation, cell survival, cell-cell contacts, epithelial mesenchymal transition (EMT), cell motility, and invasiveness. These processes are orchestrated through the fine tuning of Rac1 activity by upstream cell surface receptors and effectors that regulate the cycling Rac1-GDP (off state)/Rac1-GTP (on state), but also through the tuning of Rac1 accumulation, activity, and subcellular localization by post translational modifications or recruitment into molecular scaffolds. Another level of regulation involves Rac1 transcripts stability and splicing. Downstream, Rac1 initiates a series of signaling networks, including regulatory complex of actin cytoskeleton remodeling, activation of protein kinases (PAKs, MAPKs) and transcription factors (NFkB, Wnt/β-catenin/TCF, STAT3, Snail), production of reactive oxygen species (NADPH oxidase holoenzymes, mitochondrial ROS). Thus, this GTPase, its regulators, and effector systems might be involved at different steps of the neoplastic progression from dysplasia to the metastatic cascade. After briefly placing Rac1 and its effector systems in the more general context of intestinal homeostasis and in wound healing after intestinal injury, the present review mainly focuses on the several levels of Rac1 signaling pathway dysregulation in colorectal carcinogenesis, their biological significance, and their clinical impact.
Collapse
Affiliation(s)
- Larissa Kotelevets
- Institut National de la Santé et de la Recherche Médicale, UMR S 938, Centre de Recherche Saint-Antoine, 75012 Paris, France
- Sorbonne Université, Hôpital Saint-Antoine, Site Bâtiment Kourilsky, 75012 Paris, France
- Correspondence: (L.K.); (E.C.)
| | - Eric Chastre
- Institut National de la Santé et de la Recherche Médicale, UMR S 938, Centre de Recherche Saint-Antoine, 75012 Paris, France
- Sorbonne Université, Hôpital Saint-Antoine, Site Bâtiment Kourilsky, 75012 Paris, France
- Correspondence: (L.K.); (E.C.)
| |
Collapse
|
9
|
Kumar D, Mains RE, Eipper BA, King SM. Ciliary and cytoskeletal functions of an ancient monooxygenase essential for bioactive amidated peptide synthesis. Cell Mol Life Sci 2019; 76:2329-2348. [PMID: 30879092 PMCID: PMC6529398 DOI: 10.1007/s00018-019-03065-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/28/2019] [Accepted: 03/07/2019] [Indexed: 02/07/2023]
Abstract
Many secreted peptides used for cell-cell communication require conversion of a C-terminal glycine to an amide for bioactivity. This reaction is catalyzed only by the integral membrane protein peptidylglycine α-amidating monooxygenase (PAM). PAM has been highly conserved and is found throughout the metazoa; PAM-like sequences are also present in choanoflagellates, filastereans, unicellular and colonial chlorophyte green algae, dinoflagellates and haptophytes. Recent studies have revealed that in addition to playing a key role in peptidergic signaling, PAM also regulates ciliogenesis in vertebrates, planaria and chlorophyte algae, and is required for the stability of actin-based microvilli. Here we briefly introduce the basic principles involved in ciliogenesis, the sequential reactions catalyzed by PAM and the trafficking of PAM through the secretory and endocytic pathways. We then discuss the multi-faceted roles this enzyme plays in the formation and maintenance of cytoskeleton-based cellular protrusions and propose models for how PAM protein and amidating activity might contribute to ciliogenesis. Finally, we consider why some ciliated organisms lack PAM, and discuss the potential ramifications of ciliary localized PAM for the endocrine features commonly observed in patients with ciliopathies.
Collapse
Affiliation(s)
- Dhivya Kumar
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Betty A Eipper
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Stephen M King
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA.
| |
Collapse
|
10
|
Kratzer MC, England L, Apel D, Hassel M, Borchers A. Evolution of the Rho guanine nucleotide exchange factors Kalirin and Trio and their gene expression in Xenopus development. Gene Expr Patterns 2019; 32:18-27. [PMID: 30844509 DOI: 10.1016/j.gep.2019.02.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/26/2019] [Accepted: 02/26/2019] [Indexed: 01/23/2023]
Abstract
Guanine nucleotide exchange factors (GEFs) activate Rho GTPases by accelerating their GDP/GTP exchange. Trio and its paralog Kalirin (Kalrn) are unique members of the Rho-GEFs that harbor three catalytic domains: two functional GEF domains and a serine/threonine kinase domain. The N-terminal GEF domain activates Rac1 and RhoG GTPases, while the C-terminal GEF domain acts specifically on RhoA. Trio and Kalrn have an evolutionary conserved function in morphogenetic processes including neuronal development. De novo mutations in TRIO have lately been identified in patients with intellectual disability, suggesting that this protein family plays an important role in development and disease. Phylogenetic and domain analysis revealed that a Kalrn/Trio ancestor originated in Prebilateria and duplicated in Urbilateria to yield Kalrn and Trio. Only few taxa outside the vertebrates retained both of these highly conserved proteins. To obtain first insights into their redundant or distinct functions in a vertebrate model system, we show for the first time a detailed comparative analysis of trio and kalrn expression in Xenopus laevis development. The mRNAs are maternally transcribed and expression increases starting with neurula stages. Trio and kalrn are detected in mesoderm/somites and different neuronal populations in the neural plate/tube and later also in the brain. However, only trio is expressed in migrating neural crest cells, while kalrn expression is detected in the cranial nerves, suggesting distinct functions. Thus, our expression analysis provides a good basis for further functional studies.
Collapse
Affiliation(s)
- Marie-Claire Kratzer
- Philipps-Universität Marburg, Faculty of Biology, Molecular Embryology, Marburg, Germany; DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany
| | - Laura England
- Philipps-Universität Marburg, Faculty of Biology, Molecular Embryology, Marburg, Germany
| | - David Apel
- Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, Marburg, Germany; DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany
| | - Monika Hassel
- Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, Marburg, Germany; DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany
| | - Annette Borchers
- Philipps-Universität Marburg, Faculty of Biology, Molecular Embryology, Marburg, Germany; DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany.
| |
Collapse
|
11
|
LaRese TP, Rheaume BA, Abraham R, Eipper BA, Mains RE. Sex-Specific Gene Expression in the Mouse Nucleus Accumbens Before and After Cocaine Exposure. J Endocr Soc 2019; 3:468-487. [PMID: 30746506 PMCID: PMC6364626 DOI: 10.1210/js.2018-00313] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/09/2019] [Indexed: 12/18/2022] Open
Abstract
The nucleus accumbens plays a major role in the response of mammals to cocaine. In animal models and human studies, the addictive effects of cocaine and relapse probability have been shown to be greater in females. Sex-specific differential expression of key transcripts at baseline and after prolonged withdrawal could underlie these differences. To distinguish between these possibilities, gene expression was analyzed in four groups of mice (cycling females, ovariectomized females treated with estradiol or placebo, and males) 28 days after they had received seven daily injections of saline or cocaine. As expected, sensitization to the locomotor effects of cocaine was most pronounced in the ovariectomized mice receiving estradiol, was greater in cycling females than in males, and failed to occur in ovariectomized/placebo mice. After the 28-day withdrawal period, RNA prepared from the nucleus accumbens of the individual cocaine- or saline-injected mice was subjected to RNA sequencing analysis. Baseline expression of 3% of the nucleus accumbens transcripts differed in the cycling female mice compared with the male mice. Expression of a similar number of transcripts was altered by ovariectomy or was responsive to estradiol treatment. Nucleus accumbens transcripts differentially expressed in cycling female mice withdrawn from cocaine exhibited substantial overlap with those differentially expressed in cocaine-withdrawn male mice. A small set of transcripts were similarly affected by cocaine in the placebo- or estradiol-treated ovariectomized mice. Sex and hormonal status have profound effects on RNA expression in the nucleus accumbens of naive mice. Prolonged withdrawal from cocaine alters the expression of a much smaller number of common and sex hormone-specific transcripts.
Collapse
Affiliation(s)
- Taylor P LaRese
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Bruce A Rheaume
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Ron Abraham
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Betty A Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Richard E Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| |
Collapse
|
12
|
Sarangdhar MA, Chaubey D, Bhatt A, Km M, Kumar M, Ranjan S, Pillai B. A Novel Long Non-coding RNA, durga Modulates Dendrite Density and Expression of kalirin in Zebrafish. Front Mol Neurosci 2017; 10:95. [PMID: 28442991 PMCID: PMC5385350 DOI: 10.3389/fnmol.2017.00095] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 03/21/2017] [Indexed: 01/06/2023] Open
Abstract
Kalirin, a key player in axonal development, nerve growth and synaptic re-modeling, is implicated in many pathological conditions like schizophrenia and autism-spectrum disorders. Alternative promoters and splicing lead to functionally distinct isoforms, but the post-transcriptional regulation of Kalirin has not been studied. Here, we report a novel non-coding RNA, which we name durga, arising from the first exon of kalirin a (kalrna) in the antisense orientation in zebrafish. The kalrna and durga transcripts are barely detectable during early development, but steadily increase by 24 hours post-fertilization (hpf) as the brain develops. Over-expression of durga in the zebrafish embryo led to an increase in kalrna expression. The morphology of the neurons cultured from durga injected embryos had significantly fewer and shorter dendrites. Although durga has no apparent sequence homolog in mammals, based on gene synteny, we found a non-coding RNA arising from the 5′ end of the human Kalrn gene and expressed in the human neuronal cell line, SH-SY5Y. We propose that the zebrafish lncRNA durga maintains dendritic length and density through regulation of kalrna expression and this may have further implications in mammalian systems.
Collapse
Affiliation(s)
- Mayuresh A Sarangdhar
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India.,Academy of Scientific and Innovative Research (AcSIR)New Delhi, India
| | - Divya Chaubey
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India
| | - Abhishek Bhatt
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India
| | - Monisha Km
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India
| | - Manish Kumar
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India
| | - Shashi Ranjan
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India
| | - Beena Pillai
- Functional Genomics, Council of Scientific and Industrial Research (CSIR), Institute of Genomics and Integrative Biology (IGIB)New Delhi, India.,Academy of Scientific and Innovative Research (AcSIR)New Delhi, India
| |
Collapse
|
13
|
Lee HJ, Lee JO, Lee YW, Kim SA, Park SH, Kim HS. Kalirin, a GEF for Rac1, plays an important role in FSTL-1-mediated glucose uptake in skeletal muscle cells. Cell Signal 2017; 29:150-157. [DOI: 10.1016/j.cellsig.2016.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/27/2016] [Accepted: 10/28/2016] [Indexed: 12/22/2022]
|
14
|
Boroumand M, Ziaee S, Zarghami N, Anvari MS, Cheraghi S, Abbasi SH, Jalali A, Pourgholi L. The Kalirin Gene rs9289231 Polymorphism as a Novel Predisposing Marker for Coronary Artery Disease. Lab Med 2016; 45:302-8. [PMID: 25316661 DOI: 10.1309/lmls813zdphrfluu] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
BACKGROUND Atherosclerosis is the leading cause of death and disability worldwide. Genetic variations play a major role in the process of atherosclerosis. Recently, rs9289231 genetic variations of the Kalirin gene (KALRN) on chromosome 3q21.2 have been introduced as potential genetic markers for coronary artery disease (CAD). OBJECTIVE In this case-control study, we investigated the association between genetic susceptibility to CAD and rs9289231 G/T polymorphism, located on the KALRN gene, in an Iranian population. METHODS Our cohort consisted of 1486 individuals undergoing coronary angiography. Of these, we considered the 1007 patients with CAD to be case individuals and the 479 individuals with normal coronary conditions to be control individuals. We performed single-nucleotide polymorphism (SNP) genotyping via the high resolution melting (HRM) technique. RESULTS Our data showed that the minor allele (G) frequency of rs9289231 SNP was higher in our CAD group than that in our control group (odds ratio, 1:37; confidence interval, 1.07-1.74; P = .01). The results of our data analysis highlighted a genetic association between rs9289231 polymorphism and severity and development of CAD. CONCLUSIONS We consider the GG genotype and the G allele of rs9289231 polymorphism of KALRN to be genetic risk factors for CAD in an Iranian population, especially in early-stage atherosclerotic vascular disease.
Collapse
Affiliation(s)
- Mohammadali Boroumand
- Department of Pathology and Laboratory Medicine and Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Shayan Ziaee
- Department of Molecular Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Nosratollah Zarghami
- Department of Medical Biotechnology, Tabriz University of Medical Science, Tabriz, Iran
| | - Maryam Sotudeh Anvari
- Department of Pathology and Laboratory Medicine and Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Sara Cheraghi
- Department of Molecular Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Arash Jalali
- Department of Molecular Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Leila Pourgholi
- Department of Molecular Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| |
Collapse
|
15
|
Son K, Smith TC, Luna EJ. Supervillin binds the Rac/Rho-GEF Trio and increases Trio-mediated Rac1 activation. Cytoskeleton (Hoboken) 2015; 72:47-64. [PMID: 25655724 DOI: 10.1002/cm.21210] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/21/2015] [Indexed: 01/06/2023]
Abstract
We investigated cross-talk between the membrane-associated, myosin II-regulatory protein supervillin and the actin-regulatory small GTPases Rac1, RhoA, and Cdc42. Supervillin knockdown reduced Rac1-GTP loading, but not the GTP loading of RhoA or Cdc42, in HeLa cells with normal levels of the Rac1-activating protein Trio. No reduction in Rac1-GTP loading was observed when supervillin levels were reduced in Trio-depleted cells. Conversely, overexpression of supervillin isoform 1 (SV1) or, especially, isoform 4 (SV4) increased Rac1 activation. Inhibition of the Trio-mediated Rac1 guanine nucleotide exchange activity with ITX3 partially blocked the SV4-mediated increase in Rac1-GTP. Both SV4 and SV1 co-localized with Trio at or near the plasma membrane in ruffles and cell surface projections. Two sequences within supervillin bound directly to Trio spectrin repeats 4-7: SV1-171, which contains N-terminal residues found in both SV1 and SV4 and the SV4-specific differentially spliced coding exons 3, 4, and 5 within SV4 (SV4-E345; SV4 amino acids 276-669). In addition, SV4-E345 interacted with the homologous sequence in rat kalirin (repeats 4-7, amino acids 531-1101). Overexpressed SV1-174 and SV4-E345 affected Rac1-GTP loading, but only in cells with endogenous levels of Trio. Trio residues 771-1057, which contain both supervillin-interaction sites, exerted a dominant-negative effect on cell spreading. Supervillin and Trio knockdowns, separately or together, inhibited cell spreading, suggesting that supervillin regulates the Rac1 guanine nucleotide exchange activity of Trio, and potentially also kalirin, during cell spreading and lamellipodia extension.
Collapse
Affiliation(s)
- Kyonghee Son
- Department of Cell and Developmental Biology, Program in Cell & Developmental Dynamics, University of Massachusetts Medical School, Worcester, Massachusetts
| | | | | |
Collapse
|
16
|
Zong W, Liu S, Wang X, Zhang J, Zhang T, Liu Z, Wang D, Zhang A, Zhu M, Gao J. Trio gene is required for mouse learning ability. Brain Res 2015; 1608:82-90. [PMID: 25727174 DOI: 10.1016/j.brainres.2015.02.040] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 02/03/2015] [Accepted: 02/15/2015] [Indexed: 01/08/2023]
Abstract
Trio is a guanine nucleotide exchange factor with multiple guanine nucleotide exchange factor domains. Trio regulates cytoskeleton dynamics and actin remodeling and is involved in cell migration and axonal guidance in neuronal development. The null allele of the Trio gene led to embryonic lethality, and Trio null embryos displayed aberrant organization in several regions of the brain at E18.5, including hippocampus. Nestin-Trio-/- mice, in which the Trio gene was deleted specifically in the neuronal system by the Nestin-Cre system, displayed severe phenotypes, including low survival rate, ataxia and multiple developmental defects of the cerebellum. All Nestin-Trio-/- mice died before reaching adulthood, which hinders research on Trio gene function in adult mice. Thus, we generated EMX1-Trio-/- mice by crossing Trio-floxed mice with EMX1-Cre mice in which Cre is expressed in the brain cortex and hippocampus. EMX1-Trio-/- mice can survive to adulthood. Trio gene deletion results in smaller brains, an abnormal hippocampus and disordered granule cells in the dentate gyrus (DG) and cornu ammonis (CA). Behavior tests showed that Trio deletion interfered with the hippocampal-dependent spatial learning in the mice, suggesting that Trio plays critical roles in the learning ability of adult mice. We conclude that the Trio gene regulates the neuronal development of the hippocampus and that it affects the intelligence of adult mice.
Collapse
Affiliation(s)
- Wen Zong
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China
| | - Shuoyang Liu
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China
| | - Xiaotong Wang
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Jian Zhang
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China
| | - Tingting Zhang
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China
| | - Ziyi Liu
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China
| | - Dongdong Wang
- Department of Neurobiology, Shandong Provincial Key Laboratory of Mental Disorders, School of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Aizhen Zhang
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China
| | - Minsheng Zhu
- Model Animal Research Center, Key Laboratory of Model Animal for Disease Study of Ministry of Education, Nanjing University, Nanjing210061, China.
| | - Jiangang Gao
- Key Laboratory of the Ministry of Education for Experimental Teratology and School of Life Science, Shandong University, Jinan 250100, China.
| |
Collapse
|
17
|
Jones KA, Eng AG, Raval P, Srivastava DP, Penzes P. Scaffold protein X11α interacts with kalirin-7 in dendrites and recruits it to Golgi outposts. J Biol Chem 2014; 289:35517-29. [PMID: 25378388 PMCID: PMC4271236 DOI: 10.1074/jbc.m114.587709] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Pyramidal neurons in the mammalian forebrain receive their synaptic inputs through their dendritic trees, and dendritic spines are the sites of most excitatory synapses. Dendritic spine structure is important for brain development and plasticity. Kalirin-7 is a guanine nucleotide-exchange factor for the small GTPase Rac1 and is a critical regulator of dendritic spine remodeling. The subcellular localization of kalirin-7 is thought to be important for regulating its function in neurons. A yeast two-hybrid screen has identified the adaptor protein X11α as an interacting partner of kalirin-7. Here, we show that kalirin-7 and X11α form a complex in the brain, and this interaction is mediated by the C terminus of kalirin-7. Kalirin-7 and X11α co-localize at excitatory synapses in cultured cortical neurons. Using time-lapse imaging of fluorescence recovery after photobleaching, we show that X11α is present in a mobile fraction of the postsynaptic density. X11α also localizes to Golgi outposts in dendrites, and its overexpression induces the removal of kalirin-7 from spines and accumulation of kalirin-7 in Golgi outposts. In addition, neurons overexpressing X11α displayed thinner spines. These data support a novel mechanism of regulation of kalirin-7 localization and function in dendrites, providing insight into signaling pathways underlying neuronal plasticity. Dissecting the molecular mechanisms of synaptic structural plasticity will improve our understanding of neuropsychiatric and neurodegenerative disorders, as kalirin-7 has been associated with schizophrenia and Alzheimer disease.
Collapse
Affiliation(s)
| | - Andrew G Eng
- the Interdepartmental Neuroscience Graduate Program, Northwestern University, Chicago, Illinois 60611, and
| | - Pooja Raval
- the Department of Neuroscience and Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London SE5 9NU, United Kingdom
| | - Deepak P Srivastava
- From the Departments of Physiology and the Department of Neuroscience and Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London SE5 9NU, United Kingdom
| | - Peter Penzes
- From the Departments of Physiology and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611,
| |
Collapse
|
18
|
Schmidt S, Debant A. Function and regulation of the Rho guanine nucleotide exchange factor Trio. Small GTPases 2014; 5:e29769. [PMID: 24987837 DOI: 10.4161/sgtp.29769] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Rho GTPases oscillate between an inactive GDP-bound state and an active GTP-bound state. They are activated by Rho Guanine nucleotide Exchange Factors (GEF), which accelerate the GDP to GTP exchange. RhoGEFs fall into two different classes: the Dbl family and the DOCK family of proteins. In this review, we focus on the function and regulation of the Dbl family RhoGEF Trio. Trio and its paralog Kalirin are unique within this family in that they display two GEF domains of distinct specificity. Trio is a major regulator of neuronal development, and its function is conserved through evolution. Moreover, Trio plays an important role in cell adhesion and in signaling pathways elicited by Gαq protein-coupled receptors. Combined, these observations suggest that Trio has a major role in cellular physiology. Of note, Trio is an essential gene for mouse development, with a prominent role in the development of the nervous system. Finally, Trio expression is significantly increased in different types of tumors and it has been proposed that it could participate in oncogenesis.
Collapse
Affiliation(s)
- Susanne Schmidt
- Centre de Recherche en Biochimie Macromoléculaire; CNRS - UMR 5237; Université de Montpellier; Montpellier, France
| | - Anne Debant
- Centre de Recherche en Biochimie Macromoléculaire; CNRS - UMR 5237; Université de Montpellier; Montpellier, France
| |
Collapse
|
19
|
Molina-Navarro MM, Roselló-Lletí E, Tarazón E, Ortega A, Sánchez-Izquierdo D, Lago F, González-Juanatey JR, García-Pavía P, Salvador A, Montero JA, Portolés M, Rivera M. Heart failure entails significant changes in human nucleocytoplasmic transport gene expression. Int J Cardiol 2013; 168:2837-43. [PMID: 23651824 DOI: 10.1016/j.ijcard.2013.03.192] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/26/2013] [Accepted: 03/30/2013] [Indexed: 01/04/2023]
Abstract
BACKGROUND Heart failure (HF) induces alterations in nucleocytoplasmic transport, which is essential to the cardiomyocyte biology. The objective of this study was to analyze the changes in gene expression in human HF, particularly focusing on nucleocytoplasmic transport-related genes. METHODS AND RESULTS 29 RNA heart samples from dilated cardiomyopathy (DCM, n = 12) and ischemic cardiomyopathy (ICM, n = 12) patients undergoing heart transplantation and control donors (CNT, n = 5) were extracted to perform a microarray profiling using Affymetrix Human Gene® 1.0 ST arrays. We focused on the study of 5 nucleocytoplasmic transport-related genes, since this functional category has not previously been studied in HF. XPO1, GABPB2, and RANBP17 were upregulated, while KALRN was downregulated in both DCM and ICM, and XPO5 only in DCM. Validation of the results by RT-qPCR increasing the total heart samples up to 41 showed a high degree of consistency with microarray results. Moreover, we observed a strong relationship between the XPO1 mRNA and robust left ventricular function parameters in ICM: left ventricular end-systolic (r = 0.81, p<0.0001) and end-diastolic diameters (r = 0.80, p<0.0001), and ejection fraction (r = -0.57, p<0.05). CONCLUSIONS We show that the expression of nucleocytoplasmic transport-related genes is altered in HF. Furthermore, XPO1 mRNA level is closely related with robust left ventricular function parameters in ICM patients. These changes may help to distinguish DCM and ICM in HF at the level of the transcriptome and provide a base for novel therapeutic approaches.
Collapse
|
20
|
Tsai YC, Riess O, Soehn AS, Nguyen HP. The Guanine nucleotide exchange factor kalirin-7 is a novel synphilin-1 interacting protein and modifies synphilin-1 aggregate transport and formation. PLoS One 2012; 7:e51999. [PMID: 23284848 PMCID: PMC3527391 DOI: 10.1371/journal.pone.0051999] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 11/09/2012] [Indexed: 11/19/2022] Open
Abstract
Synphilin-1 has been identified as an interaction partner of α-synuclein, a key protein in the pathogenesis of Parkinson disease (PD). To further explore novel binding partners of synphilin-1, a yeast two hybrid screening was performed and kalirin-7 was identified as a novel interactor. We then investigated the effect of kalirin-7 on synphilin-1 aggregate formation. Coexpression of kalirin-7 and synphilin-1 caused a dramatic relocation of synphilin-1 cytoplasmic small inclusions to a single prominent, perinuclear inclusion. These perinuclear inclusions were characterized as being aggresomes according to their colocalization with microtubule organization center markers, and their formation was microtubule-dependent. Furthermore, kalirin-7 increased the susceptibility of synphilin-1 inclusions to be degraded as demonstrated by live cell imaging and quantification of aggregates. However, the kalirin-7-mediated synphilin-1 aggresome response was not dependent on the GEF activity of kalirin-7 since various dominant negative small GTPases could not inhibit the formation of aggresomes. Interestingly, the aggresome response was blocked by HDAC6 catalytic mutants and the HDAC inhibitor trichostatin A (TSA). Moreover, kalirin-7 decreased the level of acetylated α-tubulin in response to TSA, which suggests an effect of kalirin-7 on HDAC6-mediated protein transportation and aggresome formation. In summary, this is the first report demonstrating that kalirin-7 leads to the recruitment of synphilin-1 into aggresomes in a HDAC6-dependent manner and also links kalirin-7 to microtubule dynamics.
Collapse
Affiliation(s)
- Yu-Chun Tsai
- Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany
| | - Olaf Riess
- Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany
| | - Anne S. Soehn
- Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany
| | - Huu Phuc Nguyen
- Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany
- * E-mail:
| |
Collapse
|
21
|
Abstract
Small Rho-GTPases are enzymes that are bound to GDP or GTP, which determines their inactive or active state, respectively. The exchange of GDP for GTP is catalyzed by so-called Rho-guanine nucleotide exchange factors (GEFs). Rho-GEFs are characterized by a Dbl-homology (DH) and adjacent Pleckstrin-homology (PH) domain that serves as enzymatic unit for the GDP/GTP exchange. Rho-GEFs show different GTPase specificities, meaning that a particular GEF can activate either multiple GTPases or only one specific GTPase. We recently reported that the Rho-GEF Trio, known to be able to exchange GTP on Rac1, RhoG and RhoA, regulates lamellipodia formation to mediate cell spreading and migration in a Rac1-dependent manner. In this commentary, we review the current knowledge of Trio in several aspects of cell biology.
Collapse
Affiliation(s)
- Jos van Rijssel
- Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | | |
Collapse
|
22
|
Vishwanatha KS, Wang YP, Keutmann HT, Mains RE, Eipper BA. Structural organization of the nine spectrin repeats of Kalirin. Biochemistry 2012; 51:5663-73. [PMID: 22738176 DOI: 10.1021/bi300583s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Sequence analysis suggests that KALRN, a Rho GDP/GTP exchange factor genetically linked to schizophrenia, could contain as many as nine tandem spectrin repeats (SRs). We expressed and purified fragments of Kalirin containing from one to five putative SRs to determine whether they formed nested structures that could endow Kalirin with the flexible rodlike properties characteristic of spectrin and dystrophin. Far-UV circular dichroism studies indicated that Kalirin contains nine SRs. On the basis of thermal denaturation, sensitivity to chemical denaturants, and the solubility of pairs of repeats, the nine SRs of Kalirin form nested structures. Modeling studies confirmed this conclusion and identified an exposed loop in SR5; consistent with the modeling, this loop was extremely labile to proteolytic cleavage. Analysis of a direpeat fragment (SR4:5) encompassing the region of Kalirin known to interact with NOS2, DISC-1, PAM, and Arf6 identified this as the least stable region. Analytical ultracentrifugation indicated that SR1:3, SR4:6, and SR7:9 were monomers and adopted an extended conformation. Gel filtration suggested that ΔKal7, a natural isoform that includes SR5:9, was monomeric and was not more extended than SR5:9. Similarly, the nine SRs of Kal7, which was also monomeric, were not more extended than SR5:9. The rigidity and flexibility of the nine SRs of Kal7, which separate its essential N-terminal Sec14p domain from its catalytic domain, play an essential role in its contribution to the formation and function of dendritic spines.
Collapse
Affiliation(s)
- K S Vishwanatha
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
| | | | | | | | | |
Collapse
|
23
|
Tsai YC, Metzger S, Riess O, Soehn AS, Nguyen HP. Genetic analysis of polymorphisms in the kalirin gene for association with age-at-onset in European Huntington disease patients. BMC MEDICAL GENETICS 2012; 13:48. [PMID: 22720673 PMCID: PMC3433364 DOI: 10.1186/1471-2350-13-48] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 06/21/2012] [Indexed: 01/01/2023]
Abstract
Background Huntington disease (HD) is caused by an expanded CAG repeat in the HD gene. Although the length of the CAG repeat strongly correlates with the age-at-onset (AAO), AAO in HD individuals may differ dramatically in spite of similar expanded CAG repeat lengths. Additional genetic or environmental factors are thought to influence the disease onset. Several modifier genes have been discovered so far but they do not fully explain the variability of AAO in HD. To potentially identify a novel genetic modifier, we analyzed single nucleotide polymorphisms (SNPs) in the kalirin (KALRN) gene. Kalirin is a protein crucially involved in spine plasticity and its interaction with huntingtin-associated protein-1 (HAP-1) and a potential protein dysfunction might contribute to spine pathogenesis in HD. Methods The selected SNPs were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and association of SNPs with AAO was investigated with the framework of linear models in an analysis of variance and covariance. Results Eleven SNPs in the kalirin gene were examined in an association study in European HD patients. The ten coding SNPs under investigation were monomorphic, whereas SNP rs10934657 in the promoter region showed a minor allele frequency >1%. An analysis of covariance together with the influence of the expanded HD allele was applied in 680 HD patients. SNP rs10934657 did not affect the AAO of the examined HD population. Conclusions The results did not reveal an association between the analyzed kalirin polymorphisms and the AAO in HD. However, it does not exclude other SNPs of the kalirin gene as susceptible genetic modifiers.
Collapse
Affiliation(s)
- Yu-Chun Tsai
- Department of Medical Genetics, University of Tuebingen, Calwerstr 7, Tuebingen, 72076, Germany
| | | | | | | | | |
Collapse
|
24
|
Rajagopal C, Mains RE, Eipper BA. Signaling from the secretory granule to the nucleus. Crit Rev Biochem Mol Biol 2012; 47:391-406. [PMID: 22681236 DOI: 10.3109/10409238.2012.694845] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Neurons and endocrine cells use a complex array of signaling molecules to communicate with each other and with various targets. The majority of these signaling molecules are stored in specialized organelles awaiting release on demand: 40-60 nm vesicles carry conventional or small molecule neurotransmitters, and 200-400 nm granules contain bioactive peptides. The supply of small molecule neurotransmitters is tightly regulated by local feedback of synthetic rates and transport processes at sites of release. The larger granules that contain bioactive peptides present the secretory cell with special challenges, as the peptide precursors are inserted into the lumen of the secretory pathway in the cell soma and undergo biosynthetic processing while being transported to distant sites for eventual secretion. One solution to this dilemma in information handling has been to employ proteolytic cleavage of secretory granule membrane proteins to produce cytosolic fragments that can signal to the nucleus, affecting gene expression. The use of regulated intramembrane proteolysis to signal from secretory granules to the nucleus is compared to its much better understood role in relaying information from the endoplasmic reticulum by SREBP and ATF6 and from the plasma membrane by cadherins, Notch and ErbB4.
Collapse
Affiliation(s)
- Chitra Rajagopal
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| | | | | |
Collapse
|
25
|
Kalirin, a key player in synapse formation, is implicated in human diseases. Neural Plast 2012; 2012:728161. [PMID: 22548195 PMCID: PMC3324156 DOI: 10.1155/2012/728161] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 01/13/2012] [Indexed: 12/22/2022] Open
Abstract
Synapse formation is considered to be crucial for learning and memory. Understanding the underlying molecular mechanisms of synapse formation is a key to understanding learning and memory. Kalirin-7, a major isoform of Kalirin in adult rodent brain, is an essential component of mature excitatory synapses. Kalirin-7 interacts with multiple PDZ-domain-containing proteins including PSD95, spinophilin, and GluR1 through its PDZ-binding motif. In cultured hippocampal/cortical neurons, overexpression of Kalirin-7 increases spine density and spine size whereas reduction of endogenous Kalirin-7 expression decreases synapse number, and spine density. In Kalirin-7 knockout mice, spine length, synapse number, and postsynaptic density (PSD) size are decreased in hippocampal CA1 pyramidal neurons; these morphological alterations are accompanied by a deficiency in long-term potentiation (LTP) and a decreased spontaneous excitatory postsynaptic current (sEPSC) frequency. Human Kalirin-7, also known as Duo or Huntingtin-associated protein-interacting protein (HAPIP), is equivalent to rat Kalirin-7. Recent studies show that Kalirin is relevant to many human diseases such as Huntington's Disease, Alzheimer's Disease, ischemic stroke, schizophrenia, depression, and cocaine addiction. This paper summarizes our recent understanding of Kalirin function.
Collapse
|
26
|
Murray PS, Kirkwood CM, Gray MC, Ikonomovic MD, Paljug WR, Abrahamson EE, Henteleff RA, Hamilton RL, Kofler JK, Klunk WE, Lopez OL, Penzes P, Sweet RA. β-Amyloid 42/40 ratio and kalirin expression in Alzheimer disease with psychosis. Neurobiol Aging 2012; 33:2807-16. [PMID: 22429885 DOI: 10.1016/j.neurobiolaging.2012.02.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/03/2012] [Accepted: 02/12/2012] [Indexed: 12/13/2022]
Abstract
Psychosis in Alzheimer disease differentiates a subgroup with more rapid decline, is heritable, and aggregates within families, suggesting a distinct neurobiology. Evidence indicates that greater impairments of cerebral cortical synapses, particularly in dorsolateral prefrontal cortex, may contribute to the pathogenesis of psychosis in Alzheimer disease (AD) phenotype. Soluble β-amyloid induces loss of dendritic spine synapses through impairment of long-term potentiation. In contrast, the Rho guanine nucleotide exchange factor (GEF) kalirin is an essential mediator of spine maintenance and growth in cerebral cortex. We therefore hypothesized that psychosis in AD would be associated with increased soluble β-amyloid and reduced expression of kalirin in the cortex. We tested this hypothesis in postmortem cortical gray matter extracts from 52 AD subjects with and without psychosis. In subjects with psychosis, the β-amyloid(1-42)/β-amyloid(1-40) ratio was increased, due primarily to reduced soluble β-amyloid(1-40), and kalirin-7, -9, and -12 were reduced. These findings suggest that increased cortical β-amyloid(1-42)/β-amyloid(1-40) ratio and decreased kalirin expression may both contribute to the pathogenesis of psychosis in AD.
Collapse
Affiliation(s)
- Patrick S Murray
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Portales-Casamar E, Briançon-Marjollet A, Fromont S, Triboulet R, Debant A. Identification of novel neuronal isoforms of the Rho-GEF Trio. Biol Cell 2012; 98:183-93. [PMID: 16033331 DOI: 10.1042/bc20050009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION The large family of GEFs (guanine nucleotide-exchange factors) for Rho GTPases activate the GTPases by accelerating their GDP/GTP exchange. The multidomain protein Trio is the founding member of an intriguing subfamily of Rho-GEFs exhibiting two Rho-GEF and numerous additional domains. The members of the Trio family play an important role in neuronal physiology, and their structural organization is very well conserved through evolution. It has previously been shown that all the members, except mammalian Trio, display several isoforms, the functions of which have been well established. RESULTS In this study, we have identified, by a combination of different approaches, novel Trio isoforms that have been generated by alternative splicing, giving rise to proteins that exhibit one or two Rho-GEF domains (GEFDs). These isoforms are specifically expressed in the nervous system, at a higher level than the full-length Trio, which is ubiquitously expressed. In addition, we show that all the GEFD1-containing isoforms induce neurite outgrowth in neuroblastoma cells. CONCLUSIONS We have identified neuronal specific isoforms of Trio which could be essential for Trio function in neuronal morphology.
Collapse
|
28
|
Deo AJ, Cahill ME, Li S, Goldszer I, Henteleff R, Vanleeuwen JE, Rafalovich I, Gao R, Stachowski EK, Sampson AR, Lewis DA, Penzes P, Sweet RA. Increased expression of Kalirin-9 in the auditory cortex of schizophrenia subjects: its role in dendritic pathology. Neurobiol Dis 2011; 45:796-803. [PMID: 22120753 DOI: 10.1016/j.nbd.2011.11.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 11/07/2011] [Indexed: 11/25/2022] Open
Abstract
Reductions in dendritic arbor length and complexity are among the most consistently replicated changes in neuronal structure in post mortem studies of cerebral cortical samples from subjects with schizophrenia, however, the underlying molecular mechanisms have not been identified. This study is the first to identify an alteration in a regulatory protein which is known to promote both dendritic length and arborization in developing neurons, Kalirin-9. We found Kalirin-9 expression to be paradoxically increased in schizophrenia. We followed up this observation by overexpressing Kalirin-9 in mature primary neuronal cultures, causing reduced dendritic length and complexity. Kalirin-9 overexpression represents a potential mechanism for dendritic changes seen in schizophrenia.
Collapse
Affiliation(s)
- Anthony J Deo
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Plageman TF, Chauhan BK, Yang C, Jaudon F, Shang X, Zheng Y, Lou M, Debant A, Hildebrand JD, Lang RA. A Trio-RhoA-Shroom3 pathway is required for apical constriction and epithelial invagination. Development 2011; 138:5177-88. [PMID: 22031541 DOI: 10.1242/dev.067868] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Epithelial invagination is a common feature of embryogenesis. An example of invagination morphogenesis occurs during development of the early eye when the lens placode forms the lens pit. This morphogenesis is accompanied by a columnar-to-conical cell shape change (apical constriction or AC) and is known to be dependent on the cytoskeletal protein Shroom3. Because Shroom3-induced AC can be Rock1/2 dependent, we hypothesized that during lens invagination, RhoA, Rock and a RhoA guanine nucleotide exchange factor (RhoA-GEF) would also be required. In this study, we show that Rock activity is required for lens pit invagination and that RhoA activity is required for Shroom3-induced AC. We demonstrate that RhoA, when activated and targeted apically, is sufficient to induce AC and that RhoA plays a key role in Shroom3 apical localization. Furthermore, we identify Trio as a RhoA-GEF required for Shroom3-dependent AC in MDCK cells and in the lens pit. Collectively, these data indicate that a Trio-RhoA-Shroom3 pathway is required for AC during lens pit invagination.
Collapse
Affiliation(s)
- Timothy F Plageman
- The Visual Systems Group, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Rudock ME, Cox AJ, Ziegler JT, Lehtinen AB, Connelly JJ, Freedman BI, Carr JJ, Langefeld CD, Hauser ER, Horne BD, Bowden DW. Cigarette smoking status has a modifying effect on the association between polymorphisms in KALRN and measures of cardiovascular risk in the diabetes heart study. Genes Genomics 2011. [DOI: 10.1007/s13258-011-0069-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
31
|
Niciu MJ, Kelmendi B, Sanacora G. Overview of glutamatergic neurotransmission in the nervous system. Pharmacol Biochem Behav 2011; 100:656-64. [PMID: 21889952 DOI: 10.1016/j.pbb.2011.08.008] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Accepted: 08/10/2011] [Indexed: 02/07/2023]
Abstract
This introductory article to the special edition on glutamate neurotransmission in neuropsychiatric disorders provides an overview of glutamate neurotransmitter system physiology and pharmacology. Glutamate was only relatively recently recognized as the major excitatory neurotransmitter in the mammalian brain, in part due to its ubiquitous nature and diverse metabolic roles within the CNS. The extremely high concentration of glutamate in brain tissue paired with its excitotoxic potential requires tight physiological regulation of extracellular glutamate levels and receptor signaling in order to assure optimal excitatory neurotransmission but limits excitotoxic damage. In order to achieve this high level of control, the system has developed a complex physiology with multiple regulatory processes modulating glutamate metabolism, release, receptor signaling, and uptake. The basic physiology of the various regulatory components of the system including the rich receptor pharmacology is briefly reviewed. Potential contributions from each of the system's components to the pathophysiology of neuropsychiatric illnesses are briefly discussed, as are the many new pharmacological targets for drug development provided by the system, especially as they pertain to the proceeding preclinical and clinical articles in this issue.
Collapse
Affiliation(s)
- Mark J Niciu
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA
| | | | | |
Collapse
|
32
|
UNC-73/trio RhoGEF-2 activity modulates Caenorhabditis elegans motility through changes in neurotransmitter signaling upstream of the GSA-1/Galphas pathway. Genetics 2011; 189:137-51. [PMID: 21750262 DOI: 10.1534/genetics.111.131227] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Rho-family GTPases play regulatory roles in many fundamental cellular processes. Caenorhabditis elegans UNC-73 RhoGEF isoforms function in axon guidance, cell migration, muscle arm extension, phagocytosis, and neurotransmission by activating either Rac or Rho GTPase subfamilies. Multiple differentially expressed UNC-73 isoforms contain a Rac-specific RhoGEF-1 domain, a Rho-specific RhoGEF-2 domain, or both domains. The UNC-73E RhoGEF-2 isoform is activated by the G-protein subunit Gαq and is required for normal rates of locomotion; however, mechanisms of UNC-73 and Rho pathway regulation of locomotion are not clear. To better define UNC-73 function in the regulation of motility we used cell-specific and inducible promoters to examine the temporal and spatial requirements of UNC-73 RhoGEF-2 isoform function in mutant rescue experiments. We found that UNC-73E acts within peptidergic neurons of mature animals to regulate locomotion rate. Although unc-73 RhoGEF-2 mutants have grossly normal synaptic morphology and weak resistance to the acetylcholinesterase inhibitor aldicarb, they are significantly hypersensitive to the acetylcholine receptor agonist levamisole, indicating alterations in acetylcholine neurotransmitter signaling. Consistent with peptidergic neuron function, unc-73 RhoGEF-2 mutants exhibit a decreased level of neuropeptide release from motor neuron dense core vesicles (DCVs). The unc-73 locomotory phenotype is similar to those of rab-2 and unc-31, genes with distinct roles in the DCV-mediated secretory pathway. We observed that constitutively active Gαs pathway mutations, which compensate for DCV-mediated signaling defects, rescue unc-73 RhoGEF-2 and rab-2 lethargic movement phenotypes. Together, these data suggest UNC-73 RhoGEF-2 isoforms are required for proper neurotransmitter signaling and may function in the DCV-mediated neuromodulatory regulation of locomotion rate.
Collapse
|
33
|
Kiraly DD, Stone KL, Colangelo CM, Abbott T, Wang Y, Mains RE, Eipper BA. Identification of kalirin-7 as a potential post-synaptic density signaling hub. J Proteome Res 2011; 10:2828-41. [PMID: 21488700 DOI: 10.1021/pr200088w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Kalirin-7 (Kal7), a multifunctional Rho GDP/GTP exchange factor (GEF) for Rac1 and RhoG, is embedded in the postsynaptic density at excitatory synapses, where it participates in the formation and maintenance of dendritic spines. Kal7 has been implicated in long-term potentiation, fear memories, and addiction-like behaviors. Using liquid chromatography and tandem mass spectroscopy, we identified sites phosphorylated by six PSD-localized kinases implicated in synaptic plasticity and behavior, sites phosphorylated when myc-Kal7 was expressed in non-neuronal cells and sites phosphorylated in mouse brain Kal7. A site in the Sec14p domain phosphorylated by calcium/calmodulin dependent protein kinase II, protein kinase A and protein kinase C, was phosphorylated in mouse brain but not in non-neuronal cells. Phosphorylation in the spectrin-like repeat region was more extensive in mouse brain than in non-neuronal cells, with a total of 20 sites identified. Sites in the pleckstrin homology domain and in the linker region connecting the GEF domain to the PDZ binding motif were heavily phosphorylated in both non-neuronal cells and in mouse brain and affected GEF activity. We postulate that the kinase convergence and divergence observed in Kal7 identify it as a key player in integration of the multiple inputs that regulate synaptic structure and function.
Collapse
Affiliation(s)
- Drew D Kiraly
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
Bousquet-Moore D, Mains RE, Eipper BA. Peptidylgycine α-amidating monooxygenase and copper: a gene-nutrient interaction critical to nervous system function. J Neurosci Res 2011; 88:2535-45. [PMID: 20648645 DOI: 10.1002/jnr.22404] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Peptidylgycine alpha-amidating monooxygenase (PAM), a highly conserved copper-dependent enzyme, is essential for the synthesis of all amidated neuropeptides. Biophysical studies revealed that the binding of copper to PAM affects its structure, and cell biological studies demonstrated that the endocytic trafficking of PAM was sensitive to copper. We review data indicating that genetic reduction of PAM expression and mild copper deficiency in mice cause similar alterations in several physiological functions known to be regulated by neuropeptides: thermal regulation, seizure sensitivity, and anxiety-like behavior.
Collapse
|
35
|
Prosser DC, Tran D, Schooley A, Wendland B, Ngsee JK. A novel, retromer-independent role for sorting nexins 1 and 2 in RhoG-dependent membrane remodeling. Traffic 2011; 11:1347-62. [PMID: 20604901 DOI: 10.1111/j.1600-0854.2010.01100.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The sorting nexins SNX1 and SNX2 are members of the retromer complex involved in protein sorting within the endocytic pathway. While retromer-dependent functions of SNX1 and SNX2 have been well documented, potential retromer-independent roles remain unclear. Here, we show that SNX1 and SNX2 interact with the Rac1 and RhoG guanine nucleotide exchange factor Kalirin-7. Simultaneous overexpression of SNX1 or SNX2 and Kalirin-7 in epithelial cells causes partial redistribution of both SNX isoforms to the plasma membrane, and results in RhoG-dependent lamellipodia formation that requires functional Phox homology (PX) and Bin/Amphiphysin/Rvs (BAR) domains of SNX, but is Rac1- and retromer-independent. Conversely, depletion of endogenous SNX1 or SNX2 inhibits Kalirin-7-mediated lamellipodia formation. Finally, we demonstrate that SNX1 and SNX2 interact directly with inactive RhoG, suggesting a novel role for these SNX proteins in recruiting an inactive Rho GTPase to its exchange factor.
Collapse
Affiliation(s)
- Derek C Prosser
- Department of Cellular and Molecular Medicine, Ottawa Hospital Research Institute, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
| | | | | | | | | |
Collapse
|
36
|
Deletion and duplication of 15q24: Molecular mechanisms and potential modification by additional copy number variants. Genet Med 2010; 12:573-86. [DOI: 10.1097/gim.0b013e3181eb9b4a] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
|
37
|
Li W, Li QJ, An SC. Preventive effect of estrogen on depression-like behavior induced by chronic restraint stress. Neurosci Bull 2010; 26:140-6. [PMID: 20332819 DOI: 10.1007/s12264-010-0609-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVE To investigate the roles of estrogen and kalirin-7 in chronic restraint stress (CRS)-induced depression and the pathophysiological mechanism of depression. METHODS Healthy female mice from Institute of Cancer Research (ICR) were randomly divided into 3 groups: control group, CRS group, and estrogen + CRS group. CRS was used to establish the animal model of depression. Forced swimming test and immunohistochemistry method were utilized to investigate the animal behavior and kalirin-7 expression in the hippocampus, respectively. RESULTS Compared with the control group, the CRS mice displayed depression-like behaviors, including a significant reduction in body weight, a significant increase in immobility time in forced swimming test, and a dramatic decrease in kalirin-7 expression in the hippocampus. However, administration of estrogen attenuated the CRS-induced negative behaviors, and simultaneously increased kalirin-7 expression. CONCLUSION Estrogen replacement therapy (ERT) could prevent CRS-induced depression-like behaviors in female ICR mice. Besides, kalirin-7 also plays a role in preventing CRS-induced depression-like behaviors.
Collapse
Affiliation(s)
- Wei Li
- Institute of Brain and Behavior Science, College of Life Science, Shaanxi Normal University, Xi'an 710062, China
| | | | | |
Collapse
|
38
|
Modulation of Rho guanine exchange factor Lfc activity by protein kinase A-mediated phosphorylation. Mol Cell Biol 2009; 29:5963-73. [PMID: 19667072 DOI: 10.1128/mcb.01268-08] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Lfc is a guanine nucleotide exchange factor (GEF) for Rho that demonstrates an unusual ability to associate with microtubules. While several phosphorylated residues have been detected in the Lfc polypeptide, the mechanism(s) by which phosphorylation regulates the exchange activity of Lfc remains unclear. We confirm that Lfc is a phosphorylated protein and demonstrate that 14-3-3 interacts directly and in a phosphorylation-dependent manner with Lfc. We identify AKAP121 as an Lfc-binding protein and show that Lfc is phosphorylated in an AKAP-dependent manner by protein kinase A (PKA). Forskolin treatment induced 14-3-3 binding to Lfc and suppressed the exchange activity of wild-type Lfc on RhoA. Importantly, a mutant of Lfc that is unable to associate with 14-3-3 proteins was resistant to inhibition by forskolin. Tctex-1, a dynein motor light chain, binds to Lfc in a competitive manner with 14-3-3.
Collapse
|
39
|
Xin X, Wang Y, Ma XM, Rompolas P, Keutmann HT, Mains RE, Eipper BA. Regulation of Kalirin by Cdk5. J Cell Sci 2008; 121:2601-11. [PMID: 18628310 DOI: 10.1242/jcs.016089] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Kalirin, one of the few Rho guanine nucleotide exchange factors (GEFs) that contains spectrin-like repeats, plays a critical role in axon extension and maintenance of dendritic spines. PC12 cells were used to determine whether Cdk5, a critical participant in both processes, regulates the action of Kalirin. Expression of Kalirin-7 in nondifferentiated PC12 cells caused GEF-activity-dependent extension of broad cytoplasmic protrusions; coexpression of dominant-negative Cdk5 largely eliminated this response. The spectrin-like repeat region of Kalirin plays an essential role in this response, which is not mimicked by the GEF domain alone. Thr1590, which follows the first GEF domain of Kalirin, is the only Cdk5 phosphorylation site in Kalirin-7. Although mutant Kalirin-7 with Ala1590 retains GEF activity, it is unable to cause extension of protrusions. Kalirin-7 with an Asp1590 mutation has slightly increased GEF activity and dominant-negative Cdk5 fails to block its ability to cause extension of protrusions. Phosphorylation of Thr1590 causes a slight increase in GEF activity and Kalirin-7 solubility. Dendritic spines formed by cortical neurons in response to the expression of Kalirin-7 with Ala1590 differ in shape from those formed in response to wild-type Kalirin-7 or Kalirin-7 containing Asp1590. The presence of Thr1590 in each major Kalirin isoform would allow Cdk5 to regulate Kalirin function throughout development.
Collapse
Affiliation(s)
- Xiaonan Xin
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3401, USA
| | | | | | | | | | | | | |
Collapse
|
40
|
Zhao S, Xu C, Qian H, Lv L, Ji C, Chen C, Zhao X, Zheng D, Gu S, Xie Y, Mao Y. Cellular retinaldehyde-binding protein-like (CRALBPL), a novel human Sec14p-like gene that is upregulated in human hepatocellular carcinomas, may be used as a marker for human hepatocellular carcinomas. DNA Cell Biol 2008; 27:159-63. [PMID: 18271718 DOI: 10.1089/dna.2007.0634] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sec14p-like lipid-binding domain (SEC14 domain) is an evolutionarily conserved protein domain often found in secretory proteins, such as Saccharomyces cerevisiae phosphatidylinositol transfer protein Sec14p, and in lipid-regulated proteins, such as GTPase-activating proteins, guanine nucleotide exchange factors, and neurofibromin. We have cloned a novel human gene, cellular retinaldehyde-binding protein-like (CRALBPL), containing SEC14 domain from the cDNA library of human fetal brain. The RT-PCR expression pattern of 16 adult human tissues indicated that CRALBPL was only expressed in brain, while it was expressed in all of seven human carcinoma cell lines we used, especially in human gastric adenocarcinoma cell line, human rhabdomyoma cell line, human hepatocellular carcinoma (HCC) cell line, and human prostatic carcinoma cell line. Further, we found that CRALBPL has a remarkably more abundant RT-PCR expression pattern in human HCC cell lines than in normal human liver cell line, and the same result was gained when RT-PCR expression patterns between human HCC specimens and normal human liver specimens were compared. We also found that CRALBPL is located mainly in cytoplasm in human liver cell line L-02, which is consistent with the common function of Sec14p-like domain family. Our results show that CRALBPL may be used as a marker for human HCCs.
Collapse
Affiliation(s)
- Shuo Zhao
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, PR China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Schiller MR, Ferraro F, Wang Y, Ma XM, McPherson CE, Sobota JA, Schiller NI, Mains RE, Eipper BA. Autonomous functions for the Sec14p/spectrin-repeat region of Kalirin. Exp Cell Res 2008; 314:2674-91. [PMID: 18585704 DOI: 10.1016/j.yexcr.2008.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 05/16/2008] [Accepted: 05/16/2008] [Indexed: 01/22/2023]
Abstract
Kalirin is a GDP/GTP exchange factor (GEF) for Rho proteins that modulates the actin cytoskeleton in neurons. Alternative splicing generates Delta-isoforms, which encode the RhoGEF domain, but lack the N-terminal Sec14p domain and first 4 spectrin-like repeats of the full-length isoforms. Splicing has functional consequences, with Kal7 but not DeltaKal7 causing formation of dendritic spines. Cells lacking endogenous Kalirin were used to explore differences between these splice variants. Expression of DeltaKal7 in this system induces extensive lamellipodial sheets, while expression of Kal7 induces formation of adherent compact, round cells with abundant cortical actin. Based on in vitro and cell-based assays, Kal7 and DeltaKal7 are equally active GEFs, suggesting that other domains are involved in controlling cell morphology. Catalytically inactive Kal7 and a Kalirin fragment which includes only Sec14p and spectrin-like domains retain the ability to produce compact, round cells and fractionate as high molecular weight complexes. Separating the Sec14p domain from the spectrin-like repeats eliminates the ability of Kal7 to cause this response. The isolated Sec14p domain binds PI(3,5)P2 and PI3P, but does not alter cell morphology. We conclude that the Sec14p and N-terminal spectrin-like domains of Kalirin play critical roles in distinguishing the actions of full-length and Delta-Kalirin proteins.
Collapse
Affiliation(s)
- Martin R Schiller
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Ross CA, Becher MW, Colomer V, Engelender S, Wood JD, Sharp AH. Huntington's disease and dentatorubral-pallidoluysian atrophy: proteins, pathogenesis and pathology. Brain Pathol 2008; 7:1003-16. [PMID: 9217980 PMCID: PMC8098431 DOI: 10.1111/j.1750-3639.1997.tb00898.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Each of the glutamine repeat neurodegenerative diseases has a particular pattern of pathology largely restricted to the CNS. However, there is considerable overlap among the regions affected, suggesting that the diseases share pathogenic mechanisms, presumably involving the glutamine repeats. We focus on Huntington's disease (HD) and Dentatorubral-pallidoluysian atrophy (DRPLA) as models for this family of diseases, since they have striking similarities and also notable differences in their clinical features and pathology. We review the pattern of pathology in adult and juvenile onset cases. Despite selective pathology, the disease genes and their protein products (huntingtin and atrophin-1) are widely expressed. This presents a central problem for all the glutamine repeat diseases-how do widely expressed gene products give rise to restricted pathology? The pathogenic effects are believed to occur via a "gain of function" mechanism at the protein level. Mechanisms of cell death may include excitotoxicity, metabolic toxicity, apoptosis, and free radical stress. Emerging data indicate that huntingtin and atrophin-1 may have distinct protein interactions. The specific interaction partners may help explain the selective pathology of these diseases.
Collapse
Affiliation(s)
- C A Ross
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2196, USA
| | | | | | | | | | | |
Collapse
|
43
|
de Curtis I. Functions of Rac GTPases during neuronal development. Dev Neurosci 2008; 30:47-58. [PMID: 18075254 DOI: 10.1159/000109851] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 02/27/2007] [Indexed: 12/11/2022] Open
Abstract
The small GTPases of the Rho family are important regulators of the actin cytoskeleton and are critical for several aspects of neuronal development including the establishment of neuronal polarity, extension of axon and dendrites, neurite branching, axonal navigation and synapse formation. The aim of this review is to present evidence supporting the function of Rac and Rac-related proteins in different aspects of neuronal maturation, based on work performed with organisms including nematodes, Drosophila, Xenopus and mice, and with primary cultures of developing neurons. Three of the 4 vertebrate Rac-related genes, namely Rac1, Rac3 and RhoG, are expressed in the nervous system, and several data support an essential role of all 3 GTPases in distinct aspects of neuronal development and function. Two important points emerge from the analysis presented: highly homologous Rac-related proteins may perform different functions in the developing nervous system; on the other hand, the data also indicate that similar GTPases may perform redundant functions in vivo.
Collapse
Affiliation(s)
- Ivan de Curtis
- Cell Adhesion Unit, San Raffaele Scientific Institute, Milan, Italy.
| |
Collapse
|
44
|
Ferraro F, Ma XM, Sobota JA, Eipper BA, Mains RE. Kalirin/Trio Rho guanine nucleotide exchange factors regulate a novel step in secretory granule maturation. Mol Biol Cell 2007; 18:4813-25. [PMID: 17881726 PMCID: PMC2096607 DOI: 10.1091/mbc.e07-05-0503] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The molecular mechanisms involved in the maturation of secretory granules, organelles that store hormones and neuropeptides, are poorly understood. As granule content proteins are processed, the composition of granule membranes changes, yielding constitutive-like secretion of immature content proteins and producing secretagogue-responsive mature granules. Constitutive-like secretion was not previously recognized as a process subject to regulation. We show that Kalirin and Trio, homologous Rho guanine nucleotide exchange factors (GEFs), which interact with a secretory granule resident protein, modulate cargo secretion from immature granules. Some of the Kalirin and Trio isoforms expressed in neuroendocrine cells colocalize with immature granules. Overexpression of their N-terminal GEF domain (GEF1) enhances secretion from immature granules, depleting cells of secretory cargo in the absence of secretagogue. This response requires GEF1 activity and is mimicked by Kalirin/Trio substrates Rac1 and RhoG. Accordingly, selective pharmacological inhibition of endogenous GEF1 activity decreases secretagogue-independent release of hormone precursors, accumulating product peptide in mature secretory granules. Kalirin/Trio modulation of cargo secretion from immature granules provides secretory cells with an extra layer of control over the sets of peptides released. Control of this step enhances the range of physiological responses that can be elicited, whereas lack of control could have pathological consequences.
Collapse
Affiliation(s)
- Francesco Ferraro
- Neuroscience Department, University of Connecticut Health Center, Farmington, CT 06030-3401
| | - Xin-Ming Ma
- Neuroscience Department, University of Connecticut Health Center, Farmington, CT 06030-3401
| | - Jacqueline A. Sobota
- Neuroscience Department, University of Connecticut Health Center, Farmington, CT 06030-3401
| | - Betty A. Eipper
- Neuroscience Department, University of Connecticut Health Center, Farmington, CT 06030-3401
| | - Richard E. Mains
- Neuroscience Department, University of Connecticut Health Center, Farmington, CT 06030-3401
| |
Collapse
|
45
|
Arf6 recruits the Rac GEF Kalirin to the plasma membrane facilitating Rac activation. BMC Cell Biol 2007; 8:29. [PMID: 17640372 PMCID: PMC1939998 DOI: 10.1186/1471-2121-8-29] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Accepted: 07/18/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Many studies implicate Arf6 activity in Rac-mediated membrane ruffling and cytoskeletal reorganization. Although Arf6 facilitates the trafficking of Rac1 to the plasma membrane and in many cases Arf6 activation leads to the activation of Rac1, the details of how Arf6 influences Rac function remain to be elucidated. RESULTS We demonstrate in binding assays and by co-immunoprecipitation that GDP-bound Arf6 binds to Kalirin5, a Rho family guanine nucleotide exchange factor, through interaction with the spectrin repeat region. In cells, expression of wild type Arf6 recruits spectrin repeat 5 and Kalirin to the plasma membrane and leads to enhanced Kalirin5-induced ruffling. By contrast, expression of an Arf6 mutant that cannot become activated, Arf6 T27N, still recruits spectrin repeat 5 and Kalirin to membranes but inhibits Kalirin5-induced ruffling in HeLa cells. Kalirin5-induced Rac1 activation is increased by the expression of wild type Arf6 and decreased by Arf6T27N. Furthermore, expression of a catalytically-inactive mutant of Kalirin5 inhibits cytoskeletal changes observed in cells expressing EFA6, an Arf6 guanine nucleotide exchange factor that leads to activation of Rac. CONCLUSION We show here with over-expressed proteins that the GDP-bound form of Arf6 can bind to the spectrin repeat regions in Kalirin Rho family GEFs thereby recruiting Kalirin to membranes. Although Kalirin is recruited onto membranes by Arf6-GDP, subsequent Rac activation and membrane ruffling requires Arf6 activation. From these results, we suggest that Arf6 can regulate through its GTPase cycle the activation of Rac.
Collapse
|
46
|
Wang L, Hauser ER, Shah SH, Pericak-Vance MA, Haynes C, Crosslin D, Harris M, Nelson S, Hale AB, Granger CB, Haines JL, Jones CJH, Crossman D, Seo D, Gregory SG, Kraus WE, Goldschmidt-Clermont PJ, Vance JM. Peakwide mapping on chromosome 3q13 identifies the kalirin gene as a novel candidate gene for coronary artery disease. Am J Hum Genet 2007; 80:650-63. [PMID: 17357071 PMCID: PMC1852708 DOI: 10.1086/512981] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Accepted: 01/19/2007] [Indexed: 12/16/2022] Open
Abstract
A susceptibility locus for coronary artery disease (CAD) has been mapped to chromosome 3q13-21 in a linkage study of early-onset CAD. We completed an association-mapping study across the 1-LOD-unit-down supporting interval, using two independent white case-control data sets (CATHGEN, initial and validation) to evaluate association under the peak. Single-nucleotide polymorphisms (SNPs) evenly spaced at 100-kb intervals were screened in the initial data set (N=468). Promising SNPs (P<.1) were then examined in the validation data set (N=514). Significant findings (P<.05) in the combined initial and validation data sets were further evaluated in multiple independent data sets, including a family-based data set (N=2,954), an African American case-control data set (N=190), and an additional white control data set (N=255). The association between genotype and aortic atherosclerosis was examined in 145 human aortas. The peakwide survey found evidence of association in SNPs from multiple genes. The strongest associations were found in three SNPs from the kalirin (KALRN) gene, especially in patients with early-onset CAD (P=.00001-00028 in the combined CATHGEN data sets). In-depth investigation of the gene found that an intronic SNP, rs9289231, was associated with early-onset CAD in all white data sets examined (P<.05). In the joint analysis of all white early-onset CAD cases (N=332) and controls (N=546), rs9289231 was highly significant (P=.00008), with an odds-ratio estimate of 2.1. Furthermore, the risk allele of this SNP was associated with atherosclerosis burden (P=.03) in 145 human aortas. KALRN is a protein with many functions, including the inhibition of inducible nitric oxide synthase and guanine-exchange-factor activity. KALRN and two other associated genes identified in this study (CDGAP and MYLK) belong to the Rho GTPase-signaling pathway. Our data suggest the importance of the KALRN gene and the Rho GTPase-signaling pathway in the pathogenesis of CAD.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Jonathan L. Haines
- From the Center for Human Genetics (L.W.; E.R.H.; S.H.S.; M.A.P.-V.; C.H.; D.C.; M.H.; S.N.; A.B.H.; S.G.G.; J.M.V.) and Division of Cardiology (S.H.S.; C.B.G.; D.S.; W.E.K.), Department of Medicine, Duke Univeristy Medical Center, Durham, NC; Vanderbilt University, Nashville (J.L.H.); University of Wales College of Medicine, Cardiff (C.J.H.J.); University of Sheffield, Sheffield, United Kingdom (D.C.); and Miller School of Medicine, University of Miami, Miami (P.J.G.-C.)
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Steven R, Zhang L, Culotti J, Pawson T. The UNC-73/Trio RhoGEF-2 domain is required in separate isoforms for the regulation of pharynx pumping and normal neurotransmission in C. elegans. Genes Dev 2005; 19:2016-29. [PMID: 16140983 PMCID: PMC1199572 DOI: 10.1101/gad.1319905] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 07/06/2005] [Indexed: 11/24/2022]
Abstract
In both Caenorhabditis elegans and Drosophila, UNC-73/Trio functions in axon guidance by signaling through the Rac GTPase to regulate cytoskeletal rearrangements necessary for growth cone migrations. Here, we show that the complex C. elegans unc-73 gene encodes at least eight differentially expressed UNC-73 intracellular protein isoforms. Previously reported mutations affecting UNC-73 isoforms encoding the Rac-specific RhoGEF-1 domain cause uncoordinated movement, correlating with defects in axon guidance. Mutations in isoforms encoding the Rho-specific RhoGEF-2 domain, which we describe here, result in L1 stage larval lethality with no associated axon guidance defects. Isoform-specific rescue experiments reveal separate functions for the various RhoGEF-2-containing UNC-73 isoforms, which would not likely be discovered by conventional genetic screening. UNC-73 D1 and D2 appear to function redundantly in pharynx muscle to regulate the rate and strength of pharynx pumping, and in the HSN neurons and vulval muscles to control egg laying. Isoforms C1, C2, E, and F act redundantly within the nervous system to regulate the speed of locomotion. The multiple UNC-73 isoforms containing Rac- and Rho-specific RhoGEF domains therefore have distinct physiological functions. In addition to its previously identified role involving RhoGEF-1 in migrating cells and growth cones, our data indicate that UNC-73 signals through RhoGEF-2 to regulate pharynx and vulva musculature and to modulate synaptic neurotransmission.
Collapse
Affiliation(s)
- Robert Steven
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | | | | | | |
Collapse
|
48
|
Schiller MR, Blangy A, Huang J, Mains RE, Eipper BA. Induction of lamellipodia by Kalirin does not require its guanine nucleotide exchange factor activity. Exp Cell Res 2005; 307:402-17. [PMID: 15950621 DOI: 10.1016/j.yexcr.2005.03.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 03/18/2005] [Accepted: 03/18/2005] [Indexed: 11/26/2022]
Abstract
Guanine nucleotide exchange factor (GEF) domains of the Dbl family occur in a variety of proteins that include multiple protein-protein and protein-lipid interaction domains. We used an epithelial-derived cell line to investigate the mechanisms by which the two GEF domains of Kalirin, a neuronal Rho GEF, influence morphology. As expected, Kal-GEF1, an efficient GEF for Rac1 and RhoG, induced the formation of lamellipodia resembling those induced by active Rac1. Although Kal-GEF1 activated Rac and Pak, its ability to induce formation of lamellipodia was not blocked by dominant negative Rho GTPases or by catalytically inactive Pak. Consistent with this, a catalytically inactive mutant of Kal-GEF1 induced formation of lamellipodia and activated Pak. Active Pak was required for the GEF-activity independent effect of Kal-GEF1 and the lamellipodia produced were filled with ribs of filamentous actin. Kal-GEF1 and a GEF-dead mutant co-immunoprecipitated with Pak. The interaction of Kal-GEF1 with Pak is indirect and requires the regulatory protein binding domain of Pak. Filamin A, which is known to interact with and activate Pak, binds to both catalytically active and inactive Kal-GEF1, providing a link by which catalytically inactive Kal-GEF1 can activate Pak and induce lamellipodia. Together, our results indicate that Kal-GEF1 induces lamellipodia through activation of Pak, where GEF activity is not required. GEF-activity-independent effects on downstream targets may be a general property of RhoGEFs.
Collapse
Affiliation(s)
- Martin R Schiller
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030-3401, USA.
| | | | | | | | | |
Collapse
|
49
|
McPherson CE, Eipper BA, Mains RE. Multiple novel isoforms of Trio are expressed in the developing rat brain. Gene 2005; 347:125-35. [PMID: 15715966 DOI: 10.1016/j.gene.2004.12.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 11/20/2004] [Accepted: 12/15/2004] [Indexed: 11/16/2022]
Abstract
Mammalian Trio is a multifunctional, multidomain Rho guanine nucleotide exchange factor (GEF) closely related to Kalirin. Trio is important for proper axon guidance in Drosophila, and mice lacking Trio exhibit both skeletal muscle and neuronal disorders. Full length mammalian Trio and Kalirin both consist of a Sec14P-like domain, several spectrin-like domains, two Rho GEF domains each containing a Dbl-homology (DH) and a pleckstrin-homology (PH) domain, two src homology 3 domains (SH3), Ig/fibronectin-like domains (Ig/FN), and a kinase domain. We have previously described multiple isoforms of Kalirin derived through alternative splicing and multiple transcription start sites, but multiple isoforms of Trio containing different functional domains have not been described. Using a new antibody directed against the spectrin-like region of rat Trio coupled with reverse transcription PCR and cDNA sequencing, we have identified 4 novel isoforms of Trio expressed in rat cortex and cerebellum. Two isoforms, Trio 9S and Trio 9L, are derived through alternative splicing of Trio exon 48 and are abundantly expressed in rat brain. Trio 8 is expressed in postnatal day 30 and adult cerebellum, but not in cortex or skeletal muscle. Trio/duet is expressed in adult cortex and cerebellum. In the rat brain, each of these Trio isoforms is expressed at a higher level than full length Trio.
Collapse
Affiliation(s)
- Clifton E McPherson
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3401, USA
| | | | | |
Collapse
|
50
|
Rabiner CA, Mains RE, Eipper BA. Kalirin: a dual Rho guanine nucleotide exchange factor that is so much more than the sum of its many parts. Neuroscientist 2005; 11:148-60. [PMID: 15746383 DOI: 10.1177/1073858404271250] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A large number of Rho guanine nucleotide exchange factors (GEFs) and Rho GTPase activating proteins (GAPs) are used in the CNS to activate specific Rho GTPase family members, thereby inducing various signaling mechanisms that regulate neuronal shape, growth, and plasticity, in part through their effects on the actin cytoskeleton. Kalirin is a large neuronal dual Rho GEF that activates Rac1, RhoA, and RhoG via its two Rho GEF domains. This activation, which is spatially and temporally regulated, allows Kalirin to influence neurite initiation, axonal growth, and dendritic morphogenesis. In addition, this alternatively spliced gene generates developmentally regulated transcripts that yield proteins localized to the postsynaptic density (PSD). Kalirin-7, which interacts with PSD-95, is necessary for dendritic spine formation. In addition, Kalirins have the ability to regulate and influence other aspects of neuronal morphogenesis via protein-protein interactions with their other domains, including many spectrins, other protein and lipid interaction domains, and a potential kinase. These interactions have implications not only for neuronal morphogenesis but also for vesicle trafficking, secretion, neuronal maintenance, and neurodegenerative disease.
Collapse
Affiliation(s)
- Chana A Rabiner
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | | | | |
Collapse
|