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  • 1
    Publication Date: 2009-08-21
    Description: The precise spatio-temporal dynamics of protein activity are often critical in determining cell behaviour, yet for most proteins they remain poorly understood; it remains difficult to manipulate protein activity at precise times and places within living cells. Protein activity has been controlled by light, through protein derivatization with photocleavable moieties or using photoreactive small-molecule ligands. However, this requires use of toxic ultraviolet wavelengths, activation is irreversible, and/or cell loading is accomplished via disruption of the cell membrane (for example, through microinjection). Here we have developed a new approach to produce genetically encoded photoactivatable derivatives of Rac1, a key GTPase regulating actin cytoskeletal dynamics in metazoan cells. Rac1 mutants were fused to the photoreactive LOV (light oxygen voltage) domain from phototropin, sterically blocking Rac1 interactions until irradiation unwound a helix linking LOV to Rac1. Photoactivatable Rac1 (PA-Rac1) could be reversibly and repeatedly activated using 458- or 473-nm light to generate precisely localized cell protrusions and ruffling. Localized Rac activation or inactivation was sufficient to produce cell motility and control the direction of cell movement. Myosin was involved in Rac control of directionality but not in Rac-induced protrusion, whereas PAK was required for Rac-induced protrusion. PA-Rac1 was used to elucidate Rac regulation of RhoA in cell motility. Rac and Rho coordinate cytoskeletal behaviours with seconds and submicrometre precision. Their mutual regulation remains controversial, with data indicating that Rac inhibits and/or activates Rho. Rac was shown to inhibit RhoA in mouse embryonic fibroblasts, with inhibition modulated at protrusions and ruffles. A PA-Rac crystal structure and modelling revealed LOV-Rac interactions that will facilitate extension of this photoactivation approach to other proteins.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2766670/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2766670/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wu, Yi I -- Frey, Daniel -- Lungu, Oana I -- Jaehrig, Angelika -- Schlichting, Ilme -- Kuhlman, Brian -- Hahn, Klaus M -- GM057464/GM/NIGMS NIH HHS/ -- GM64346/GM/NIGMS NIH HHS/ -- R01 GM057464/GM/NIGMS NIH HHS/ -- R01 GM057464-09/GM/NIGMS NIH HHS/ -- U54 GM064346/GM/NIGMS NIH HHS/ -- U54 GM064346-089026/GM/NIGMS NIH HHS/ -- England -- Nature. 2009 Sep 3;461(7260):104-8. doi: 10.1038/nature08241. Epub 2009 Aug 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA. yiwu@med.unc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19693014" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Avena/genetics ; Cell Line ; *Cell Movement/radiation effects ; Cell Surface Extensions ; Cell Survival ; Cryptochromes ; Crystallization ; Crystallography, X-Ray ; Embryo, Mammalian/cytology ; Enzyme Activation/radiation effects ; Fibroblasts ; Flavoproteins/chemistry/genetics/metabolism ; Fluorescence Recovery After Photobleaching ; Genetic Engineering/*methods ; HeLa Cells ; Humans ; Mice ; Models, Molecular ; Myosins/metabolism ; Protein Conformation ; rac1 GTP-Binding Protein/chemistry/*genetics/*metabolism/radiation effects ; rho GTP-Binding Proteins/antagonists & inhibitors/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2015-09-10
    Description: Dendritic spines are the major loci of synaptic plasticity and are considered as possible structural correlates of memory. Nonetheless, systematic manipulation of specific subsets of spines in the cortex has been unattainable, and thus, the link between spines and memory has been correlational. We developed a novel synaptic optoprobe, AS-PaRac1 (activated synapse targeting photoactivatable Rac1), that can label recently potentiated spines specifically, and induce the selective shrinkage of AS-PaRac1-containing spines. In vivo imaging of AS-PaRac1 revealed that a motor learning task induced substantial synaptic remodelling in a small subset of neurons. The acquired motor learning was disrupted by the optical shrinkage of the potentiated spines, whereas it was not affected by the identical manipulation of spines evoked by a distinct motor task in the same cortical region. Taken together, our results demonstrate that a newly acquired motor skill depends on the formation of a task-specific dense synaptic ensemble.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4634641/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4634641/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hayashi-Takagi, Akiko -- Yagishita, Sho -- Nakamura, Mayumi -- Shirai, Fukutoshi -- Wu, Yi I -- Loshbaugh, Amanda L -- Kuhlman, Brian -- Hahn, Klaus M -- Kasai, Haruo -- GM102924/GM/NIGMS NIH HHS/ -- NS071216/NS/NINDS NIH HHS/ -- R01 GM102924/GM/NIGMS NIH HHS/ -- R21 NS071216/NS/NINDS NIH HHS/ -- England -- Nature. 2015 Sep 17;525(7569):333-8. doi: 10.1038/nature15257. Epub 2015 Sep 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033. ; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan. ; CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan. ; Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut 06032, USA. ; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA. ; Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA. ; Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26352471" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Dendritic Spines/physiology/radiation effects ; Hippocampus/cytology/physiology/radiation effects ; In Vitro Techniques ; Light ; Long-Term Potentiation/physiology/radiation effects ; Male ; Memory/*physiology/*radiation effects ; Mice ; Molecular Probes ; Motor Cortex/cytology/*physiology/*radiation effects ; Motor Skills/physiology/radiation effects ; Neuronal Plasticity/*physiology/*radiation effects ; Rotarod Performance Test ; Spatio-Temporal Analysis ; Synapses/*physiology/*radiation effects
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2004-04-26
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 4
    Publication Date: 2015-01-21
    Description: Polarized Rac1 signaling is a hallmark of many cellular functions, including cell adhesion, motility, and cell division. The two steps of Rac1 activation are its translocation to the plasma membrane and the exchange of nucleotide from GDP to GTP. It is, however, unclear whether these two processes are regulated independent...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 5
    Publication Date: 1971-05-01
    Print ISSN: 0556-2813
    Electronic ISSN: 1089-490X
    Topics: Physics
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  • 6
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