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Gauthier-Fisher A, Lin DC, Greeve M, Kaplan DR, Rottapel R, Miller FD. Lfc and Tctex-1 regulate the genesis of neurons from cortical precursor cells. Nat Neurosci 2009; 12:735-44. [DOI: 10.1038/nn.2339] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 03/31/2009] [Indexed: 12/20/2022]
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Dupré DJ, Robitaille M, Rebois RV, Hébert TE. The role of Gbetagamma subunits in the organization, assembly, and function of GPCR signaling complexes. Annu Rev Pharmacol Toxicol 2009; 49:31-56. [PMID: 18834311 DOI: 10.1146/annurev-pharmtox-061008-103038] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The role of Gbetagamma subunits in cellular signaling has become well established in the past 20 years. Not only do they regulate effectors once thought to be the sole targets of Galpha subunits, but it has become clear that they also have a unique set of binding partners and regulate signaling pathways that are not always localized to the plasma membrane. However, this may be only the beginning of the story. Gbetagamma subunits interact with G protein-coupled receptors, Galpha subunits, and several different effector molecules during assembly and trafficking of receptor-based signaling complexes and not simply in response to ligand stimulation at sites of receptor cellular activity. Gbetagamma assembly itself seems to be tightly regulated via the action of molecular chaperones and in turn may serve a similar role in the assembly of specific signaling complexes. We propose that specific Gbetagamma subunits have a broader role in controlling the architecture, assembly, and activity of cellular signaling pathways.
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Affiliation(s)
- Denis J Dupré
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada.
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Montani L, Gerrits B, Gehrig P, Kempf A, Dimou L, Wollscheid B, Schwab ME. Neuronal Nogo-A modulates growth cone motility via Rho-GTP/LIMK1/cofilin in the unlesioned adult nervous system. J Biol Chem 2009; 284:10793-807. [PMID: 19208621 DOI: 10.1074/jbc.m808297200] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Nogo-A has been extensively studied as a myelin-associated neurite outgrowth inhibitor in the lesioned adult central nervous system. However, its role in the intact central nervous system has not yet been clarified. Analysis of the intact adult nervous system of C57BL/6 Nogo-A knock-out (KO) versus wild-type (WT) mice by a combined two-dimensional gel electrophoresis and isotope-coded affinity tagging approach revealed regulation of cytoskeleton-, transport-, and signaling growth-related proteins, pointing to regulation of the actin cytoskeleton, the neuronal growth machinery, and in particular the Rho-GTPase/LIMK1/cofilin pathway. Nogo-A KO adult neurons showed enlarged, more motile growth cones compared with WT neurons. The phenotype was reproduced by acute in vitro neutralization of neuronal Nogo-A. LIMK1 phosphorylation was increased in Nogo-A KO growth cones, and its reduction caused the decrease of KO growth cone motility to WT levels. Our study suggests that in the unlesioned adult nervous system, neuronal Nogo-A can restrict neuronal growth through negative modulation of growth cone motility.
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Affiliation(s)
- Laura Montani
- Brain Research Institute and Functional Genomics Center, University of Zurich, Switzerland
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Chang HCH, Dimlich DN, Yokokura T, Mukherjee A, Kankel MW, Sen A, Sridhar V, Fulga TA, Hart AC, Van Vactor D, Artavanis-Tsakonas S. Modeling spinal muscular atrophy in Drosophila. PLoS One 2008; 3:e3209. [PMID: 18791638 PMCID: PMC2527655 DOI: 10.1371/journal.pone.0003209] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 08/18/2008] [Indexed: 01/17/2023] Open
Abstract
Spinal Muscular Atrophy (SMA), a recessive hereditary neurodegenerative disease in humans, has been linked to mutations in the survival motor neuron (SMN) gene. SMA patients display early onset lethality coupled with motor neuron loss and skeletal muscle atrophy. We used Drosophila, which encodes a single SMN ortholog, survival motor neuron (Smn), to model SMA, since reduction of Smn function leads to defects that mimic the SMA pathology in humans. Here we show that a normal neuromuscular junction (NMJ) structure depends on SMN expression and that SMN concentrates in the post-synaptic NMJ regions. We conducted a screen for genetic modifiers of an Smn phenotype using the Exelixis collection of transposon-induced mutations, which affects approximately 50% of the Drosophila genome. This screen resulted in the recovery of 27 modifiers, thereby expanding the genetic circuitry of Smn to include several genes not previously known to be associated with this locus. Among the identified modifiers was wishful thinking (wit), a type II BMP receptor, which was shown to alter the Smn NMJ phenotype. Further characterization of two additional members of the BMP signaling pathway, Mothers against dpp (Mad) and Daughters against dpp (Dad), also modify the Smn NMJ phenotype. The NMJ defects caused by loss of Smn function can be ameliorated by increasing BMP signals, suggesting that increased BMP activity in SMA patients may help to alleviate symptoms of the disease. These results confirm that our genetic approach is likely to identify bona fide modulators of SMN activity, especially regarding its role at the neuromuscular junction, and as a consequence, may identify putative SMA therapeutic targets.
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Affiliation(s)
- Howard Chia-Hao Chang
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Douglas N. Dimlich
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Takakazu Yokokura
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ashim Mukherjee
- Department of Molecular and Human Genetics, Banaras Hindu University, Varanasi, India
| | - Mark W. Kankel
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anindya Sen
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Vasanthi Sridhar
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Tudor A. Fulga
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anne C. Hart
- Massachusetts General Hospital, Cancer Center and Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - David Van Vactor
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Spyros Artavanis-Tsakonas
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Collège de France, Paris, France
- * E-mail:
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Abstract
G protein betagamma subunits are central participants in G protein-coupled receptor signaling pathways. They interact with receptors, G protein alpha subunits and downstream targets to coordinate multiple, different GPCR functions. Much is known about the biology of Gbetagamma subunits but mysteries remain. Here, we will review what is known about general aspects of structure and function of Gbetagamma as well as discuss emerging mechanisms for regulation of Gbetagamma signaling. Recent data suggest that Gbetagamma is a potential therapeutic drug target. Thus, a thorough understanding of the molecular and physiological functions of Gbetagamma has significant implications.
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Affiliation(s)
- A V Smrcka
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
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