1
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Banerjee R, Gunawardena S. Glycogen synthase kinase 3β (GSK3β) and presenilin (PS) are key regulators of kinesin-1-mediated cargo motility within axons. Front Cell Dev Biol 2023; 11:1202307. [PMID: 37363727 PMCID: PMC10288942 DOI: 10.3389/fcell.2023.1202307] [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: 04/08/2023] [Accepted: 05/25/2023] [Indexed: 06/28/2023] Open
Abstract
It has been a quarter century since the discovery that molecular motors are phosphorylated, but fundamental questions still remain as to how specific kinases contribute to particular motor functions, particularly in vivo, and to what extent these processes have been evolutionarily conserved. Such questions remain largely unanswered because there is no cohesive strategy to unravel the likely complex spatial and temporal mechanisms that control motility in vivo. Since diverse cargoes are transported simultaneously within cells and along narrow long neurons to maintain intracellular processes and cell viability, and disruptions in these processes can lead to cancer and neurodegeneration, there is a critical need to better understand how kinases regulate molecular motors. Here, we review our current understanding of how phosphorylation can control kinesin-1 motility and provide evidence for a novel regulatory mechanism that is governed by a specific kinase, glycogen synthase kinase 3β (GSK3β), and a scaffolding protein presenilin (PS).
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Affiliation(s)
- Rupkatha Banerjee
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL, United States
| | - Shermali Gunawardena
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, United States
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2
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Wan B, Belghazi M, Lemauf S, Poirié M, Gatti JL. Proteomics of purified lamellocytes from Drosophila melanogaster HopT um-l identifies new membrane proteins and networks involved in their functions. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 134:103584. [PMID: 34033897 DOI: 10.1016/j.ibmb.2021.103584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
In healthy Drosophila melanogaster larvae, plasmatocytes and crystal cells account for 95% and 5% of the hemocytes, respectively. A third type of hemocytes, lamellocytes, are rare, but their number increases after oviposition by parasitoid wasps. The lamellocytes form successive layers around the parasitoid egg, leading to its encapsulation and melanization, and finally the death of this intruder. However, the total number of lamellocytes per larva remains quite low even after parasitoid infestation, making direct biochemical studies difficult. Here, we used the HopTum-l mutant strain that constitutively produces large numbers of lamellocytes to set up a purification method and analyzed their major proteins by 2D gel electrophoresis and their plasma membrane surface proteins by 1D SDS-PAGE after affinity purification. Mass spectrometry identified 430 proteins from 2D spots and 344 affinity-purified proteins from 1D bands, for a total of 639 unique proteins. Known lamellocyte markers such as PPO3 and the myospheroid integrin were among the components identified with specific chaperone proteins. Affinity purification detected other integrins, as well as a wide range of integrin-associated proteins involved in the formation and function of cell-cell junctions. Overall, the newly identified proteins indicate that these cells are highly adapted to the encapsulation process (recognition, motility, adhesion, signaling), but may also have several other physiological functions (such as secretion and internalization of vesicles) under different signaling pathways. These results provide the basis for further in vivo and in vitro studies of lamellocytes, including the development of new markers to identify coexisting populations and their respective origins and functions in Drosophila immunity.
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Affiliation(s)
- Bin Wan
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France
| | - Maya Belghazi
- Institute of NeuroPhysiopathology (INP), UMR7051, CNRS, Aix-Marseille Université, Marseille, 13015, France
| | - Séverine Lemauf
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France
| | - Marylène Poirié
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France
| | - Jean-Luc Gatti
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France.
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3
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Palu RAS, Ong E, Stevens K, Chung S, Owings KG, Goodman AG, Chow CY. Natural Genetic Variation Screen in Drosophila Identifies Wnt Signaling, Mitochondrial Metabolism, and Redox Homeostasis Genes as Modifiers of Apoptosis. G3 (BETHESDA, MD.) 2019; 9:3995-4005. [PMID: 31570502 PMCID: PMC6893197 DOI: 10.1534/g3.119.400722] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/26/2019] [Indexed: 12/22/2022]
Abstract
Apoptosis is the primary cause of degeneration in a number of neuronal, muscular, and metabolic disorders. These diseases are subject to a great deal of phenotypic heterogeneity in patient populations, primarily due to differences in genetic variation between individuals. This creates a barrier to effective diagnosis and treatment. Understanding how genetic variation influences apoptosis could lead to the development of new therapeutics and better personalized treatment approaches. In this study, we examine the impact of the natural genetic variation in the Drosophila Genetic Reference Panel (DGRP) on two models of apoptosis-induced retinal degeneration: overexpression of p53 or reaper (rpr). We identify a number of known apoptotic, neural, and developmental genes as candidate modifiers of degeneration. We also use Gene Set Enrichment Analysis (GSEA) to identify pathways that harbor genetic variation that impact these apoptosis models, including Wnt signaling, mitochondrial metabolism, and redox homeostasis. Finally, we demonstrate that many of these candidates have a functional effect on apoptosis and degeneration. These studies provide a number of avenues for modifying genes and pathways of apoptosis-related disease.
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Affiliation(s)
- Rebecca A S Palu
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Elaine Ong
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Kaitlyn Stevens
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Shani Chung
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Katie G Owings
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Alan G Goodman
- School of Molecular Biosciences, and
- Paul G. Allen School for Global Animal Health, Washington State University College of Veterinary Medicine, Pullman, WA 99164
| | - Clement Y Chow
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112,
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4
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The Extracellular and Cytoplasmic Domains of Syndecan Cooperate Postsynaptically to Promote Synapse Growth at the Drosophila Neuromuscular Junction. PLoS One 2016; 11:e0151621. [PMID: 26987116 PMCID: PMC4795781 DOI: 10.1371/journal.pone.0151621] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/01/2016] [Indexed: 11/19/2022] Open
Abstract
The heparan sulfate proteoglycan (HSPG) Syndecan (Sdc) is a crucial regulator of synapse development and growth in both vertebrates and invertebrates. In Drosophila, Sdc binds via its extracellular heparan sulfate (HS) sidechains to the receptor protein tyrosine phosphatase LAR to promote the morphological growth of the neuromuscular junction (NMJ). To date, however, little else is known about the molecular mechanisms by which Sdc functions to promote synapse growth. Here we show that all detectable Sdc found at the NMJ is provided by the muscle, strongly suggesting a post-synaptic role for Sdc. We also show that both the cytoplasmic and extracellular domains of Sdc are required to promote synapse growth or to rescue Sdc loss of function. We report the results of a yeast two-hybrid screen using the cytoplasmic domains of Sdc as bait, and identify several novel candidate binding partners for the cytoplasmic domains of Sdc. Together, these studies provide new insight into the mechanism of Sdc function at the NMJ, and provide enticing future directions for further exploring how Sdc promotes synapse growth.
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5
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Zheng ZZ, Chao ML, Fan ZB, Zhao YJ, Song HS. Molecular cloning and characterization of presenilin gene in Bombyx mori. Mol Med Rep 2015; 12:5508-16. [PMID: 26133988 DOI: 10.3892/mmr.2015.4019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 06/05/2015] [Indexed: 11/06/2022] Open
Abstract
Presenilin (PS), the catalytic core of the γ-secretase complex, is considered to be a causative protein of the early‑onset familial form of Alzheimer's disease. Aging is a risk factor for Alzheimer's disease and a number of genetic studies have utilized Bombyx mori (B. mori) as a model, making it possible to use B. mori to investigate Alzheimer's disease. However, the homologous gene of human PS in B. mori has remained to be elucidated. In the present study, the PS homologue gene in B. mori was identified and characterized, and six B. mori presenilin (BmPS) mRNA transcripts were generated by selecting multiple transcription start sites and/or alternative splice sites. The longest mRNA of BmPS (termed BmPS1) contains a 153 nt 5' untranslated region (UTR), a 1,440 nt open reading frame and a 1,063 nt 3' UTR. The predicted protein of BmPS1 consists of 479 amino acid residues and has two highly‑conserved aspartate residues, which form the catalytic core of aspartic proteases. It exhibits a sequence identity of ~44 and 51% with homologues in Homo sapiens and Drosophila melanogaster, respectively. However, the amino acid sequence of the BmPS loop region does not completely match between the two B. mori strains R13Q and Dazao. Genomic analysis revealed that B. mori had a single copy of the BmPS gene, which was composed of 14 exons. A total of four isoforms of BmPS (BmPS‑A, ‑B, ‑C and ‑D) owing to multiple transcriptional start sites and alternative splice sites were identified. The alternative splicing events occurring in the loop region improved the diversity of the BmPS protein and were detectable in all tissues, as determined using reverse transcription quantitative polymerase chain reaction (RT‑qPCR). Furthermore, the expression levels of BmPS in the brain at different developmental stages were detected using RT‑qPCR, and significantly higher expression levels of BmPS were found in the adult stage compared with those in the larval and pupal stages. The present study on BmPS provided insight into the pathogenesis of Alzheimer's disease and mechanisms of silkworm developmental regulation.
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Affiliation(s)
- Zeng-Zhang Zheng
- Department of Neurosciences, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Meng-Ling Chao
- Department of Neurosciences, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Zong-Biao Fan
- Department of Neurosciences, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Yi-Jiao Zhao
- Department of Neurosciences, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Hong-Sheng Song
- Department of Neurosciences, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
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6
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Smolarkiewicz M, Skrzypczak T, Wojtaszek P. The very many faces of presenilins and the γ-secretase complex. PROTOPLASMA 2013; 250:997-1011. [PMID: 23504135 PMCID: PMC3788181 DOI: 10.1007/s00709-013-0494-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 03/01/2013] [Indexed: 05/02/2023]
Abstract
Presenilin is a central, catalytic component of the γ-secretase complex which conducts intramembrane cleavage of various protein substrates. Although identified and mainly studied through its role in the development of amyloid plaques in Alzheimer disease, γ-secretase has many other important functions. The complex seems to be evolutionary conserved throughout the Metazoa, but recent findings in plants and Dictyostelium discoideum as well as in archeons suggest that its evolution and functions might be much more diversified than previously expected. In this review, a selective survey of the multitude of functions of presenilins and the γ-secretase complex is presented. Following a brief overview of γ-secretase structure, assembly and maturation, three functional aspects are analyzed: (1) the role of γ-secretase in autophagy and phagocytosis; (2) involvement of the complex in signaling related to endocytosis; and (3) control of calcium fluxes by presenilins.
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Affiliation(s)
- Michalina Smolarkiewicz
- Department of Molecular and Cellular Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Tomasz Skrzypczak
- Department of Molecular and Cellular Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Przemysław Wojtaszek
- Department of Molecular and Cellular Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
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7
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Abstract
Filamins are essential, evolutionarily conserved, modular, multidomain, actin-binding proteins that organize the actin cytoskeleton and maintain extracellular matrix connections by anchoring actin filaments to transmembrane receptors. By cross-linking and anchoring actin filaments, filamins stabilize the plasma membrane, provide cellular cortical rigidity, and contribute to the mechanical stability of the plasma membrane and the cell cortex. In addition to binding actin, filamins interact with more than 90 other binding partners including intracellular signaling molecules, receptors, ion channels, transcription factors, and cytoskeletal and adhesion proteins. Thus, filamins scaffold a wide range of signaling pathways and are implicated in the regulation of a diverse array of cellular functions including motility, maintenance of cell shape, and differentiation. Here, we review emerging structural and functional evidence that filamins are mechanosensors and/or mechanotransducers playing essential roles in helping cells detect and respond to physical forces in their local environment.
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Affiliation(s)
- Ziba Razinia
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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8
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Zhong Y, Shtineman-Kotler A, Nguyen L, Iliadi KG, Boulianne GL, Rotin D. A splice isoform of DNedd4, DNedd4-long, negatively regulates neuromuscular synaptogenesis and viability in Drosophila. PLoS One 2011; 6:e27007. [PMID: 22110599 PMCID: PMC3215714 DOI: 10.1371/journal.pone.0027007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/07/2011] [Indexed: 11/29/2022] Open
Abstract
Background Neuromuscular (NM) synaptogenesis is a tightly regulated process. We previously showed that in flies, Drosophila Nedd4 (dNedd4/dNedd4S) is required for proper NM synaptogenesis by promoting endocytosis of commissureless from the muscle surface, a pre-requisite step for muscle innervation. DNedd4 is an E3 ubiquitin ligase comprised of a C2-WW(x3)-Hect domain architecture, which includes several splice isoforms, the most prominent ones are dNedd4-short (dNedd4S) and dNedd4-long (dNedd4Lo). Methodology/Principal Findings We show here that while dNedd4S is essential for NM synaptogenesis, the dNedd4Lo isoform inhibits this process and causes lethality. Our results reveal that unlike dNedd4S, dNedd4Lo cannot rescue the lethality of dNedd4 null (DNedd4T121FS) flies. Moreover, overexpression of UAS-dNedd4Lo specifically in wildtype muscles leads to NM synaptogenesis defects, impaired locomotion and larval lethality. These negative effects of dNedd4Lo are ameliorated by deletion of two regions (N-terminus and Middle region) unique to this isoform, and by inactivating the catalytic activity of dNedd4Lo, suggesting that these unique regions, as well as catalytic activity, are responsible for the inhibitory effects of dNedd4Lo on synaptogenesis. In accord with these findings, we demonstrate by sqRT-PCR an increase in dNedd4S expression relative to the expression of dNedd4Lo during embryonic stages when synaptogenesis takes place. Conclusion/Significance Our studies demonstrate that splice isoforms of the same dNedd4 gene can lead to opposite effects on NM synaptogenesis.
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Affiliation(s)
- Yunan Zhong
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Alina Shtineman-Kotler
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Leo Nguyen
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Konstantin G. Iliadi
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Gabrielle L. Boulianne
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Daniela Rotin
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
- * E-mail:
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9
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Barakat A, Mercer B, Cooper E, Chung HM. Examining requirement for formation of functional Presenilin proteins and their processing events in vivo. Genesis 2009; 47:161-8. [PMID: 19191327 DOI: 10.1002/dvg.20475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Presenilin (Psn) is a multipass transmembrane protein that functions as the catalytic subunit of gamma-secretase for mediating intramembrane cleavage of type 1 transmembrane proteins. Normally active Psn is in the form of a heterodimer composed by its N-terminal and C-terminal fragments that are generated from a Presenilinase-mediated endoproteolytic cleavage within its large cytosolic loop during assembly of the protease complex. Using the Psn forms that either bypass or disable Presenilinase-mediated endoproteolysis, and a Psn form that has most of the large cytosolic loop deleted, we have established an in vivo system to enable investigations of Psn functional domains in Drosophila. We show that the Presenilinase-mediated endoproteolytic event is not essential for producing Psn activity during animal development, and is regulated by integrity of the large cytosolic loop of Psn in Drosophila. The Psn transgenic flies described here could be applied to a broad range of studies on Psn functioning and its related gamma-secretase activity at any developmental stage.
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Affiliation(s)
- Ala Barakat
- Department of Biology, University of West Florida, Pensacola, Florida, USA
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10
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Park JH, Kim HJ, Choy HE, Kim K. Presence of presenilin 1/2 affects the invasion and replication of Salmonella typhimurium. Biochem Biophys Res Commun 2005; 332:1081-5. [PMID: 15922300 DOI: 10.1016/j.bbrc.2005.05.060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Accepted: 05/02/2005] [Indexed: 11/26/2022]
Abstract
In this study, we used four different cell lines, with or without presenilin-1 or -2, to investigate the hypothesis that the presence of presenilin, the most prominently mutated gene in Alzheimer's patients, affects the infection rate of host cells by Salmonella. The invasion and replication of Salmonella in presenilin 1/2-deficient cells were significantly lower than those in presenilin 1/2-expressing cells. Among several presenilin-interacting proteins, the expression of filamin-A in presenilin 1/2-deficient cells was significantly lower than in presenilin 1/2-expressing cells. However, Salmonella infection of filamin-A-deficient M2 cells did not significantly differ from infection of filamin-A-containing A7 cells, ruling out the possibility that filamin-A is a major protein inhibiting Salmonella invasion and replication. It is of interest to note that Hes-1 expression, a downstream target of Notch signaling pathway, was significantly decreased by Salmonella infection. Our results demonstrate that the presence of presenilins affects the invasion and replication processes of Salmonella.
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Affiliation(s)
- Jae-Hyo Park
- College of Pharmacy, Chonnam National University, Kwangju, Republic of Korea
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11
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Abstract
Familial AD (Alzheimer's disease) is a rare autosomal dominant form of AD, associated with clinical and pathological features similar to those identified in the more prevalent sporadic AD cases. The majority of familial AD cases are caused by mutations in either of the highly homologous PS (presenilins), an essential component of the γ-secretase enzyme complex, or amyloid precursor protein, a γ-secretase substrate and the precursor of amyloid β peptides. The observation that PS are absolutely required for γ-secretase activity, and parallel studies demonstrating that PS interact with several signalling molecules, modulate their stability or regulate their proteolysis, have led to the suggestion that involvement of PS in additional signalling pathways mediating key cellular functions may contribute to the pathogenesis and progression of neurodegeneration. In this paper, we review PS-regulated molecules, their role in cell signalling and possible involvement in neurodegeneration in patients suffering from AD.
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Affiliation(s)
- J V McCarthy
- Signal Transduction Laboratory, Biochemistry Department, Biosciences Institute, University College Cork, Cork, Ireland.
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12
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Louvi A, Sisodia SS, Grove EA. Presenilin 1 in migration and morphogenesis in the central nervous system. Development 2004; 131:3093-105. [PMID: 15163631 DOI: 10.1242/dev.01191] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Morphogenesis of the central nervous system relies in large part upon the correct migration of neuronal cells from birthplace to final position. Two general modes of migration govern CNS morphogenesis: radial, which is mostly glia-guided and topologically relatively simple; and tangential, which often involves complex movement of neurons in more than one direction. We describe the consequences of loss of function of presenilin 1 on these fundamental processes. Previous studies of the central nervous system in presenilin 1 homozygote mutant embryos identified a premature neuronal differentiation that is transient and localized, with cortical dysplasia at later stages. We document widespread effects on CNS morphogenesis that appear strongly linked to defective neuronal migration. Loss of presenilin 1 function perturbs both radial and tangential migration in cerebral cortex, and several tangential migratory pathways in the brainstem. The inability of cells to execute their migratory trajectories affects cortical lamination, formation of the facial branchiomotor nucleus, the spread of cerebellar granule cell precursors to form the external granule layer and development of the pontine nuclei. Finally, overall morphogenesis of the mid-hindbrain region is abnormal,resulting in incomplete midline fusion of the cerebellum and overgrowth of the caudal midbrain. These observations indicate that in the absence of presenilin 1 function, the ability of a cell to move can be severely impaired regardless of its mode of migration, and, at a grosser level, brain morphogenesis is perturbed. Our results demonstrate that presenilin 1 plays a much more important role in brain development than has been assumed, consistent with a pleiotropic involvement of this molecule in cellular signaling.
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Affiliation(s)
- Angeliki Louvi
- Department of Neurobiology, Pharmacology and Physiology, University of Chicago, 947 E. 58th Street, Chicago, IL 60637, USA.
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13
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Abstract
A number of approaches have been taken to recreate and to study the role of genes associated with human neurodegenerative diseases in the model organism Drosophila. These studies encompass the polyglutamine diseases, Parkinson's disease, Alzheimer's disease, and tau-associated pathologies. The findings highlight Drosophila as an important model system in which to study the fundamental pathways influenced by these genes and have led to new insights into aspects of pathogenesis and modifier mechanisms.
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Affiliation(s)
- Nancy M Bonini
- Department of Biology, Howard Hughes Medical Institute, University of Pennsylvania, 415 S. University Avenue, Philadelphia, PA 19104-6018, USA.
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14
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Abstract
Abstract
In Alzheimer's disease and related disorders, the microtubule-associated protein Tau is abnormally hyperphosphorylated and aggregated into neurofibrillary tangles. Mutations in the tau gene cause familial frontotemporal dementia. To investigate the molecular mechanisms responsible for Tau-induced neurodegeneration, we conducted a genetic modifier screen in a Drosophila model of tauopathy. Kinases and phosphatases comprised the major class of modifiers recovered, and several candidate Tau kinases were similarly shown to enhance Tau toxicity in vivo. Despite some clinical and pathological similarities among neurodegenerative disorders, a direct comparison of modifiers between different Drosophila disease models revealed that the genetic pathways controlling Tau and polyglutamine toxicity are largely distinct. Our results demonstrate that kinases and phosphatases control Tau-induced neurodegeneration and have important implications for the development of therapies in Alzheimer's disease and related disorders.
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Affiliation(s)
- Joshua M Shulman
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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15
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van der Flier A, Kuikman I, Kramer D, Geerts D, Kreft M, Takafuta T, Shapiro SS, Sonnenberg A. Different splice variants of filamin-B affect myogenesis, subcellular distribution, and determine binding to integrin [beta] subunits. J Cell Biol 2002; 156:361-76. [PMID: 11807098 PMCID: PMC2199218 DOI: 10.1083/jcb.200103037] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Integrins connect the extracellular matrix with the cell interior, and transduce signals through interactions of their cytoplasmic tails with cytoskeletal and signaling proteins. Using the yeast two-hybrid system, we isolated a novel splice variant (filamin-Bvar-1) of the filamentous actin cross-linking protein, filamin-B, that interacts with the cytoplasmic domain of the integrin beta1A and beta1D subunits. RT-PCR analysis showed weak, but wide, expression of filamin-Bvar-1 and a similar splice variant of filamin-A (filamin-Avar-1) in human tissues. Furthermore, alternative splice variants of filamin-B and filamin-C, from which the flexible hinge-1 region is deleted (DeltaH1), were induced during in vitro differentiation of C2C12 mouse myoblasts. We show that both filamin-Avar-1 and filamin-Bvar-1 bind more strongly than their wild-type isoforms to different integrin beta subunits. The mere presence of the high-affinity binding site for beta1A is not sufficient for targeting the filamin-Bvar-1 construct to focal contacts. Interestingly, the simultaneous deletion of the H1 region is required for the localization of filamin-B at the tips of actin stress fibers. When expressed in C2C12 cells, filamin-Bvar-1(DeltaH1) accelerates their differentiation into myotubes. Furthermore, filamin-B variants lacking the H1 region induce the formation of thinner myotubes than those in cells containing variants with this region. These findings suggest that specific combinations of filamin mRNA splicing events modulate the organization of the actin cytoskeleton and the binding affinity for integrins.
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Affiliation(s)
- Arjan van der Flier
- Netherlands Cancer Institute, Division of Cell Biology, 1066 CX Amsterdams, Netherlands
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16
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Zhang SX, Guo Y, Boulianne GL. Identification of a novel family of putative methyltransferases that interact with human and Drosophila presenilins. Gene 2001; 280:135-44. [PMID: 11738826 DOI: 10.1016/s0378-1119(01)00770-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Mutations in the presenilin genes have been shown to cause the majority of cases of early-onset familial Alzheimer's disease (AD). In addition to their role in AD, presenilins are also known to function during development by interacting with the Notch pathway. To determine if presenilins have additional functions during development and AD we have used a yeast two-hybrid approach to search for proteins that can bind to presenilins. Here, we show the identification and characterization of a novel putative methyltransferase (Metl) that interacts with the loop region of Drosophila presenilin as well as human presenilin-1 and presenilin-2, suggesting that this interaction is evolutionarily conserved and functionally important. Metl appears to be a member of a conserved family of methyltransferases that share homology with, but are distinct from, the UbiE family of methyltransferases involved in ubiquinone and menaquinone biosynthesis. In Drosophila, the metl gene gives rise to two major isoforms by alternative splicing that are broadly expressed throughout development and found in the central nervous system in an overlapping pattern with Drosophila presenilin. Finally, we show that two independent dominant adult phenotypes produced by overexpression of presenilin can be enhanced by overexpression of metl in the same tissue. Taken together, these results suggest that presenilin and Metl functionally and genetically interact during development.
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Affiliation(s)
- S X Zhang
- Program in Developmental Biology, The Hospital for Sick Children, 555 University Avenue, Ontario, Toronto, Canada
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van der Flier A, Sonnenberg A. Structural and functional aspects of filamins. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1538:99-117. [PMID: 11336782 DOI: 10.1016/s0167-4889(01)00072-6] [Citation(s) in RCA: 321] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Filamins are a family of high molecular mass cytoskeletal proteins that organize filamentous actin in networks and stress fibers. Over the past few years it has become clear that filamins anchor various transmembrane proteins to the actin cytoskeleton and provide a scaffold for a wide range of cytoplasmic signaling proteins. The recent cloning of three human filamins and studies on filamin orthologues from chicken and Drosophila revealed unexpected complexity of the filamin family, the biological implications of which have just started to be addressed. Expression of dysfunctional filamin-A leads to the genetic disorder of ventricular heterotopia and gives reason to expect that abnormalities in the other isogenes may also be connected with human disease. In this review aspects of filamin structure, its splice variants, binding partners and biological function will be discussed.
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Affiliation(s)
- A van der Flier
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
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Stossel TP, Condeelis J, Cooley L, Hartwig JH, Noegel A, Schleicher M, Shapiro SS. Filamins as integrators of cell mechanics and signalling. Nat Rev Mol Cell Biol 2001; 2:138-45. [PMID: 11252955 DOI: 10.1038/35052082] [Citation(s) in RCA: 771] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Filamins are large actin-binding proteins that stabilize delicate three-dimensional actin webs and link them to cellular membranes. They integrate cellular architectural and signalling functions and are essential for fetal development and cell locomotion. Here, we describe the history, structure and function of this group of proteins.
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Affiliation(s)
- T P Stossel
- Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
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