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Yoshida Y, Oikawa M, Shimada T, Shinomiya A, Watanabe Y. Neonatal malnutrition impacts fibroblast growth factor 21-induced neuron neurite outgrowth and growth hormone-releasing hormone secretion in neonatal mouse brain. Biochem Biophys Res Commun 2023; 676:121-131. [PMID: 37506473 DOI: 10.1016/j.bbrc.2023.07.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/12/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
Neonatal malnutrition is one of the most common causes of neurological disorders. However, the mechanism of action of the factors associated with neonatal nutrition in the brain remains unclear. In this study, we focused on fibroblast growth factor (FGF) 21 to elucidate the effects of malnutrition on the neonatal brain. FGF21 is an endocrine factor produced by the liver during lactation which is the main source of nutrition during the neonatal period. In this study, malnourishment during nursing mice induced decreased levels of Fgf21 mRNA in the liver and decreased levels of FGF21 in the serum. RNA-seq analysis of neonatal mouse brain tissue revealed that FGF21 controlled the expression of Kalrn-201 in the neonatal mouse brain. Kalrn-201 is a transcript of Kalirin, a Ras homologous guanine nucleotide exchange factor at the synapse. In mouse neurons, FGF21 induced the expression of Kalirin-7 (a Kalirin isoform) by down-regulating Kalrn-201. FGF21-induced Kalirin-7 stimulated neurite outgrowth in Neuro-2a cells. FGF21 also induced Growth hormone-releasing hormone (GHRH) expression in Neuro-2a cells. Kalirin-7 and GHRH expression induced by FGF21 was altered by inhibiting the activity of SH2-containing tyrosine phosphatase (SHP2) which is located downstream of the FGF receptor (FGFR). Additionally, malnourished nursing induced intron retention of the SHP2 gene (Ptpn11), resulting in the alteration of Kalirin-7 and GHRH expression by FGF21 signaling. Ptpn11 intron retention is suggested to be involved in regulating SHP2 activity. Taken together, these results suggest that FGF21 plays a critical role in the induction of neuronal neurite outgrowth and GHRH secretion in the neonatal brain, and this mechanism is regulated by SHP2. Thus, Ptpn11 intron retention induced by malnourished nursing may be involved in SHP2 activity.
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Affiliation(s)
- Yuko Yoshida
- Faculty of Pharmacy, Musashino University, Tokyo, 202-8585, Japan; Research Institute of Pharmaceutical Sciences, Musashino University, Tokyo, 202-8585, Japan.
| | - Mana Oikawa
- Faculty of Pharmacy, Musashino University, Tokyo, 202-8585, Japan
| | - Taiga Shimada
- Faculty of Pharmacy, Musashino University, Tokyo, 202-8585, Japan
| | - Ai Shinomiya
- Faculty of Pharmacy, Musashino University, Tokyo, 202-8585, Japan
| | - Yoshifumi Watanabe
- Faculty of Pharmacy, Musashino University, Tokyo, 202-8585, Japan; Research Institute of Pharmaceutical Sciences, Musashino University, Tokyo, 202-8585, Japan
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2
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Chen L, Luo T, Cui W, Zhu M, Xu Z, Huang H. Kalirin is involved in epileptogenesis by modulating the activity of the Rac1 signaling pathway. J Chem Neuroanat 2023; 131:102289. [PMID: 37196826 DOI: 10.1016/j.jchemneu.2023.102289] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 05/19/2023]
Abstract
BACKGROUND AND OBJECTIVE Epilepsy is a common chronic brain disease. Despite the availability of various anti-seizure drugs, approximately 30 % of patients do not respond to treatment. Recent research suggests that Kalirin plays a role in regulating neurological function. However, the pathogenesis of Kalirin in epileptic seizures remains unclear. This study aims to investigate the role and mechanism of Kalirin in epileptogenesis. MATERIALS AND METHODS An epileptic model was induced by intraperitoneal injection of pentylenetetrazole (PTZ). Endogenous Kalirin was inhibited using shRNA. The expression of Kalirin, Rac1, and Cdc42 in the hippocampal CA1 region was measured using Western blotting. Spine and synaptic structures were examined using Golgi staining and electron microscopy. Moreover, the necrotic neurons in CA1 were examined using HE staining. RESULTS The results indicated that the epileptic score increased in epileptic animals, while inhibition of Kalirin decreased the epileptic scores and increased the latent period of the first seizure attack. Inhibition of Kalirin attenuated the increases in Rac1 expression, dendritic spine density, and synaptic vesicle number in the CA1 region induced by PTZ. However, the increase in Cdc42 expression was not affected by the inhibition of Kalirin. CONCLUSION This study suggests that Kalirin is involved in the development of seizures by modulating the activity of Rac1, providing a novel anti-epileptic target.
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Affiliation(s)
- Ling Chen
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi, Guizhou province 563003, China
| | - Ting Luo
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi, Guizhou province 563003, China
| | - Wenxiu Cui
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi, Guizhou province 563003, China
| | - ManMing Zhu
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi, Guizhou province 563003, China
| | - Zucai Xu
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi, Guizhou province 563003, China
| | - Hao Huang
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, 149 Dalian Road, Zunyi, Guizhou province 563003, China.
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3
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Rai SK, Singh D, Sarangi PP. Role of RhoG as a regulator of cellular functions: integrating insights on immune cell activation, migration, and functions. Inflamm Res 2023:10.1007/s00011-023-01761-9. [PMID: 37378671 DOI: 10.1007/s00011-023-01761-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/10/2023] [Accepted: 06/19/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND RhoG is a multifaceted member of the Rho family of small GTPases, sharing the highest sequence identity with the Rac subfamily members. It acts as a molecular switch, when activated, plays a central role in regulating the fundamental processes in immune cells, such as actin-cytoskeleton dynamics, transendothelial migration, survival, and proliferation, including immunological functions (e.g., phagocytosis and trogocytosis) during inflammatory responses. METHOD We have performed a literature review based on published original and review articles encompassing the significant effect of RhoG on immune cell functions from central databases, including PubMed and Google Scholar. RESULTS AND CONCLUSIONS Recently published data shows that the dynamic expression of different transcription factors, non-coding RNAs, and the spatiotemporal coordination of different GEFs with their downstream effector molecules regulates the cascade of Rho signaling in immune cells. Additionally, alterations in RhoG-specific signaling can lead to physiological, pathological, and developmental adversities. Several mutations and RhoG-modulating factors are also known to pre-dispose the downstream signaling with abnormal gene expression linked to multiple diseases. This review focuses on the cellular functions of RhoG, interconnecting different signaling pathways, and speculates the importance of this small GTPase as a prospective target against several pathological conditions.
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Affiliation(s)
- Shubham Kumar Rai
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Divya Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Pranita P Sarangi
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India.
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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.
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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.
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Abstract
The cognitive dysfunction experienced by patients with schizophrenia represents a major unmet clinical need. We believe that enhancing synaptic function and plasticity by targeting kalirin may provide a novel means to remediate these symptoms. Karilin (a protein encoded by the KALRN gene) has multiple functional domains, including two Dbl homology (DH) guanine exchange factor (GEF) domains, which act to enhance the activity of the Rho family guanosine triphosphate (GTP)-ases. Here, we provide an overview of kalirin's roles in brain function and its therapeutic potential in schizophrenia. We outline how it mediates diverse effects via a suite of distinct isoforms that couple to members of the Rho GTPase family to regulate synapse formation and stabilisation, and how genomic and post-mortem data implicate it in schizophrenia. We then review the current state of knowledge about the influence of kalirin on brain function at a systems level, based largely on evidence from transgenic mouse models, which support its proposed role in regulating dendritic spine function and plasticity. We demonstrate that, whilst the GTPases are classically considered to be 'undruggable', targeting kalirin and other Rho GEFs provides a means to indirectly modulate their activity. Finally, we integrate across the information presented to assess the therapeutic potential of kalirin for schizophrenia and highlight the key outstanding questions required to advance it in this capacity; namely, the need for more information about the diversity and function of its isoforms, how these change across neurodevelopment, and how they affect brain function in vivo.
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Duman JG, Blanco FA, Cronkite CA, Ru Q, Erikson KC, Mulherkar S, Saifullah AB, Firozi K, Tolias KF. Rac-maninoff and Rho-vel: The symphony of Rho-GTPase signaling at excitatory synapses. Small GTPases 2022; 13:14-47. [PMID: 33955328 PMCID: PMC9707551 DOI: 10.1080/21541248.2021.1885264] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 01/15/2023] Open
Abstract
Synaptic connections between neurons are essential for every facet of human cognition and are thus regulated with extreme precision. Rho-family GTPases, molecular switches that cycle between an active GTP-bound state and an inactive GDP-bound state, comprise a critical feature of synaptic regulation. Rho-GTPases are exquisitely controlled by an extensive suite of activators (GEFs) and inhibitors (GAPs and GDIs) and interact with many different signalling pathways to fulfill their roles in orchestrating the development, maintenance, and plasticity of excitatory synapses of the central nervous system. Among the mechanisms that control Rho-GTPase activity and signalling are cell surface receptors, GEF/GAP complexes that tightly regulate single Rho-GTPase dynamics, GEF/GAP and GEF/GEF functional complexes that coordinate multiple Rho-family GTPase activities, effector positive feedback loops, and mutual antagonism of opposing Rho-GTPase pathways. These complex regulatory mechanisms are employed by the cells of the nervous system in almost every step of development, and prominently figure into the processes of synaptic plasticity that underlie learning and memory. Finally, misregulation of Rho-GTPases plays critical roles in responses to neuronal injury, such as traumatic brain injury and neuropathic pain, and in neurodevelopmental and neurodegenerative disorders, including intellectual disability, autism spectrum disorder, schizophrenia, and Alzheimer's Disease. Thus, decoding the mechanisms of Rho-GTPase regulation and function at excitatory synapses has great potential for combatting many of the biggest current challenges in mental health.
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Affiliation(s)
- Joseph G. Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Francisco A. Blanco
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Integrative Molecular and Biomedical Science Graduate Program, Baylor College of Medicine, Houston, TX, USA
| | - Christopher A. Cronkite
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
| | - Qin Ru
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kelly C. Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Ali Bin Saifullah
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Karen Firozi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kimberley F. Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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Villar-Quiles RN, Le VT, Leonard-Louis S, Trang NT, Huong NT, Laddada L, Francou B, Maisonobe T, Azzedine H, Stojkovic T. Leukoencephalopathy and conduction blocks in PLEKHG5-associated intermediate CMT disease. Neuromuscul Disord 2021; 31:756-764. [PMID: 34244018 DOI: 10.1016/j.nmd.2021.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 02/05/2023]
Abstract
Biallelic variants in PLEKHG5 have been reported so far associated with different clinical phenotypes including Lower motor neuron disease (LMND) [also known as distal hereditary motor neuropathies (dHMN or HMN) or distal spinal muscular atrophy (DSMA4)] and intermediate Charcot-Marie-Tooth disease (CMT). We report four patients from two families presenting with intermediate CMT and atypical clinical and para-clinical findings. Patients presented with predominant distal weakness with none or mild sensory involvement and remain ambulant at last examination (22-36 years). Nerve conduction studies revealed, in all patients, intermediate motor nerve conduction velocities, reduced sensory amplitudes and multiple conduction blocks in upper limbs, outside of typical nerve compression sites. CK levels were strikingly elevated (1611-3867 U/L). CSF protein content was mildly elevated in two patients. Diffuse bilateral white matter lesions were detected in one patient. Genetic analysis revealed three novel frameshift variants c.1835_1860del and c.2308del (family 1) and c.104del (family 2). PLEKHG5-associated disease ranges from pure motor phenotypes with predominantly proximal involvement to intermediate CMT with predominant distal motor involvement and mild sensory symptoms. Leukoencephalopathy, elevated CK levels and the presence of conduction blocks associated with intermediate velocities in NCS are part of the phenotype and may arise suspicion of the disease, thus avoiding misdiagnosis and unnecessary therapeutics in these patients.
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Affiliation(s)
- Rocio-Nur Villar-Quiles
- Reference Center for Neuromuscular Disorders, APHP(,) Pitié-Salpêtrière Hospital, Paris, France; Centre de Recherche en Myologie, GH Pitié-Salpêtrière, Sorbonne Université-Inserm UMRS974, Paris(,) France
| | - Van Thuy Le
- Neurology department, Hanoi Medical University Hospital, Hanoi, Viet Nam
| | - Sarah Leonard-Louis
- Reference Center for Neuromuscular Disorders, APHP(,) Pitié-Salpêtrière Hospital, Paris, France
| | - Nguyen Thi Trang
- Genetics department, Hanoi Medical University Hospital, Hanoi Medical University Hanoi, Viet Nam
| | - Nguyen Thi Huong
- Neurology department, Hanoi Medical University Hospital, Hanoi, Viet Nam; Vinmec International Hospital, Hanoi, Viet Nam
| | - Lilia Laddada
- Department of Molecular Genetics Pharmacogenomics and Hormonology, APHP, Bicêtre Hospital, Paris, France; Plateforme d'expertise maladies rares AP-HP. Université Paris-Saclay(,) Le Kremlin Bicêtre(,) France
| | - Bruno Francou
- Department of Molecular Genetics Pharmacogenomics and Hormonology, APHP, Bicêtre Hospital, Paris, France
| | - Thierry Maisonobe
- Department of Neurophysiology, APHP, Hôpital Pitié Salpêtrière, Paris, France
| | - Hamid Azzedine
- Department of Pathology and Neuropathology, AMC, Amsterdam, Netherlands
| | - Tanya Stojkovic
- Reference Center for Neuromuscular Disorders, APHP(,) Pitié-Salpêtrière Hospital, Paris, France; Centre de Recherche en Myologie, GH Pitié-Salpêtrière, Sorbonne Université-Inserm UMRS974, Paris(,) France.
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8
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Afanasyeva EA, Gartlgruber M, Ryl T, Decaesteker B, Denecker G, Mönke G, Toprak UH, Florez A, Torkov A, Dreidax D, Herrmann C, Okonechnikov K, Ek S, Sharma AK, Sagulenko V, Speleman F, Henrich KO, Westermann F. Kalirin-RAC controls nucleokinetic migration in ADRN-type neuroblastoma. Life Sci Alliance 2021; 4:e201900332. [PMID: 33658318 PMCID: PMC8017594 DOI: 10.26508/lsa.201900332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 02/12/2021] [Accepted: 02/17/2021] [Indexed: 12/12/2022] Open
Abstract
The migrational propensity of neuroblastoma is affected by cell identity, but the mechanisms behind the divergence remain unknown. Using RNAi and time-lapse imaging, we show that ADRN-type NB cells exhibit RAC1- and kalirin-dependent nucleokinetic (NUC) migration that relies on several integral components of neuronal migration. Inhibition of NUC migration by RAC1 and kalirin-GEF1 inhibitors occurs without hampering cell proliferation and ADRN identity. Using three clinically relevant expression dichotomies, we reveal that most of up-regulated mRNAs in RAC1- and kalirin-GEF1-suppressed ADRN-type NB cells are associated with low-risk characteristics. The computational analysis shows that, in a context of overall gene set poverty, the upregulomes in RAC1- and kalirin-GEF1-suppressed ADRN-type cells are a batch of AU-rich element-containing mRNAs, which suggests a link between NUC migration and mRNA stability. Gene set enrichment analysis-based search for vulnerabilities reveals prospective weak points in RAC1- and kalirin-GEF1-suppressed ADRN-type NB cells, including activities of H3K27- and DNA methyltransferases. Altogether, these data support the introduction of NUC inhibitors into cancer treatment research.
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Affiliation(s)
- Elena A Afanasyeva
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Moritz Gartlgruber
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Tatsiana Ryl
- Department of Neurosurgery, University of Duisburg Essen, Essen, Germany
| | - Bieke Decaesteker
- Center for Medical Genetics, Ghent University, and Cancer Research Institute Ghent, Ghent, Belgium
| | - Geertrui Denecker
- Center for Medical Genetics, Ghent University, and Cancer Research Institute Ghent, Ghent, Belgium
| | - Gregor Mönke
- European Molecular Biology Laboratories, Heidelberg, Germany
| | - Umut H Toprak
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Andres Florez
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
- Center for Systems Biology, Faculty of Arts and Sciences, Harvard University, Cambridge, MA, USA
| | - Alica Torkov
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Daniel Dreidax
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Carl Herrmann
- Group of Cancer Regulatory Genomics B086, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Konstantin Okonechnikov
- Department of Pediatric Neurooncology, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Sara Ek
- Department of Immunotechnology, CREATE Health, Faculty of Engineering, Lund University, Lund, Sweden
| | - Ashwini Kumar Sharma
- Institute for Pharmacy and Molecular Biotechnology and BioQuant, Heidelberg University, Heidelberg, Germany
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Vitaliya Sagulenko
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Frank Speleman
- Center for Medical Genetics, Ghent University, and Cancer Research Institute Ghent, Ghent, Belgium
| | - Kai-Oliver Henrich
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
| | - Frank Westermann
- Department of Neuroblastoma Genomics, Hopp-Children's Cancer Center at the (NCT) Nationales Centrum für Tumorerkrankungen Heidelberg (KiTZ), Heidelberg, Germany
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9
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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.
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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
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10
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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.
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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.
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11
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Paskus JD, Herring BE, Roche KW. Kalirin and Trio: RhoGEFs in Synaptic Transmission, Plasticity, and Complex Brain Disorders. Trends Neurosci 2020; 43:505-518. [PMID: 32513570 DOI: 10.1016/j.tins.2020.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/15/2020] [Accepted: 05/05/2020] [Indexed: 02/07/2023]
Abstract
Changes in the actin cytoskeleton are a primary mechanism mediating the morphological and functional plasticity that underlies learning and memory. The synaptic Ras homologous (Rho) guanine nucleotide exchange factors (GEFs) Kalirin and Trio have emerged as central regulators of actin dynamics at the synapse. The increased attention surrounding Kalirin and Trio stems from the growing evidence for their roles in the etiology of a wide range of neurodevelopmental and neurodegenerative disorders. In this Review, we discuss recent findings revealing the unique and diverse functions of these paralog proteins in neurodevelopment, excitatory synaptic transmission, and plasticity. We additionally survey the growing literature implicating these proteins in various neurological disorders.
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Affiliation(s)
- Jeremiah D Paskus
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
| | - Bruce E Herring
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Katherine W Roche
- Receptor Biology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, USA.
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12
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Humphries BA, Wang Z, Yang C. MicroRNA Regulation of the Small Rho GTPase Regulators-Complexities and Opportunities in Targeting Cancer Metastasis. Cancers (Basel) 2020; 12:E1092. [PMID: 32353968 PMCID: PMC7281527 DOI: 10.3390/cancers12051092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 02/07/2023] Open
Abstract
The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.
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Affiliation(s)
- Brock A. Humphries
- Center for Molecular Imaging, Department of Radiology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Zhishan Wang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
| | - Chengfeng Yang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
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13
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Katsuno T, Belyantseva IA, Cartagena-Rivera AX, Ohta K, Crump SM, Petralia RS, Ono K, Tona R, Imtiaz A, Rehman A, Kiyonari H, Kaneko M, Wang YX, Abe T, Ikeya M, Fenollar-Ferrer C, Riordan GP, Wilson EA, Fitzgerald TS, Segawa K, Omori K, Ito J, Frolenkov GI, Friedman TB, Kitajiri SI. TRIOBP-5 sculpts stereocilia rootlets and stiffens supporting cells enabling hearing. JCI Insight 2019; 4:128561. [PMID: 31217345 DOI: 10.1172/jci.insight.128561] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 05/08/2019] [Indexed: 01/19/2023] Open
Abstract
TRIOBP remodels the cytoskeleton by forming unusually dense F-actin bundles and is implicated in human cancer, schizophrenia, and deafness. Mutations ablating human and mouse TRIOBP-4 and TRIOBP-5 isoforms are associated with profound deafness, as inner ear mechanosensory hair cells degenerate after stereocilia rootlets fail to develop. However, the mechanisms regulating formation of stereocilia rootlets by each TRIOBP isoform remain unknown. Using 3 new Triobp mouse models, we report that TRIOBP-5 is essential for thickening bundles of F-actin in rootlets, establishing their mature dimensions and for stiffening supporting cells of the auditory sensory epithelium. The coiled-coil domains of this isoform are required for reinforcement and maintenance of stereocilia rootlets. A loss of TRIOBP-5 in mouse results in dysmorphic rootlets that are abnormally thin in the cuticular plate but have increased widths and lengths within stereocilia cores, and causes progressive deafness recapitulating the human phenotype. Our study extends the current understanding of TRIOBP isoform-specific functions necessary for life-long hearing, with implications for insight into other TRIOBPopathies.
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Affiliation(s)
- Tatsuya Katsuno
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Alexander X Cartagena-Rivera
- Section on Auditory Mechanics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Keisuke Ohta
- Advanced Imaging Research Center, Kurume University School of Medicine, Kurume, Japan
| | - Shawn M Crump
- Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Kazuya Ono
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Risa Tona
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Ayesha Imtiaz
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Atteeq Rehman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Hiroshi Kiyonari
- Laboratory for Animal Resources and Genetic Engineering, Riken Center for Biosystems Dynamics Research, Kobe, Japan
| | - Mari Kaneko
- Laboratory for Animal Resources and Genetic Engineering, Riken Center for Biosystems Dynamics Research, Kobe, Japan
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Takaya Abe
- Laboratory for Animal Resources and Genetic Engineering, Riken Center for Biosystems Dynamics Research, Kobe, Japan
| | - Makoto Ikeya
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Cristina Fenollar-Ferrer
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA.,Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, NIH, Bethesda, Maryland, USA
| | - Gavin P Riordan
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Elisabeth A Wilson
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Tracy S Fitzgerald
- Mouse Auditory Testing Core Facility, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Kohei Segawa
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Koichi Omori
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Juichi Ito
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | | | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland, USA
| | - Shin-Ichiro Kitajiri
- Department of Otolaryngology-Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
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14
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Li MX, Qiao H, Zhang M, Ma XM. Role of Cdk5 in Kalirin7-Mediated Formation of Dendritic Spines. Neurochem Res 2019; 44:1243-1251. [PMID: 30875016 DOI: 10.1007/s11064-019-02771-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 03/04/2019] [Accepted: 03/07/2019] [Indexed: 02/06/2023]
Abstract
A majority of excitatory synapses in the brain are localized on the dendritic spines. Alterations of spine density and morphology are associated with many neurological diseases. Understanding the molecular mechanisms underlying spine formation is important for understanding these diseases. Kalirin7 (Kal-7) is localized to the postsynaptic side of excitatory synapses in the neurons. Overexpression of Kal-7 causes an increase in spine density whereas knockdown expression of endogenous Kal-7 results in a decrease in spine density in primary cultured cortical neurons. However, the mechanisms underlying Kal-7-mediated spine formation are not entirely clear. Cyclin-dependent kinase 5 (Cdk5) plays a vital role in the formation of spines and synaptic plasticity. Kal-7 is phosphorylated by CDK5 at Thr1590, the unique Cdk5 phosphorylation site in the Kal-7 protein. This study was to explore the role of CDK5-mediated phosphorylation of Kal-7 in spine formation and the underlying mechanisms. Our results showed expression of Kal-7T/D (mimicked phosphorylation), Kal-7T/A mutants (blocked phosphorylation) or wild-type (Wt) Kal-7 caused in a similar increase in spine density, while spine size of Wt Kal-7-expressing cortical neurons was bigger than that in Kal-7 T\A-expressing neurons, but smaller than that in Kal-7T/D-expressing neurons. The fluorescence intensity of NMDA receptor subunit NR2B (GluN2B) staining was stronger along the MAP2 positive dendrites of Kal-7T/D-expressing neurons than that in Kal-7T/A- or Wt Kal-7-expressing neurons. The fluorescence intensity of AMPA receptor subunit GluR1 (GluA1) staining showed the same trend as GluN2B staining. These findings suggest that Cdk5 affects the function of Kal-7 on spine morphology and function via GluN2B and GluA1 receptors during dendritic spine formation.
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Affiliation(s)
- Ming-Xing Li
- State Key Laboratory of Subtropical Agro-Bioresource Conservation and Utilization, Guangxi University, Nanning, 530004, Guangxi, China
- College of Life Science, Shaanxi Normal University, Xi'an, 710062, Shaanxi, China
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Hui Qiao
- College of Life Science, Shaanxi Normal University, Xi'an, 710062, Shaanxi, China
| | - Ming Zhang
- State Key Laboratory of Subtropical Agro-Bioresource Conservation and Utilization, Guangxi University, Nanning, 530004, Guangxi, China
| | - Xin-Ming Ma
- College of Life Science, Shaanxi Normal University, Xi'an, 710062, Shaanxi, China.
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030, USA.
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15
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Valdivia A, Goicoechea SM, Awadia S, Zinn A, Garcia-Mata R. Regulation of circular dorsal ruffles, macropinocytosis, and cell migration by RhoG and its exchange factor, Trio. Mol Biol Cell 2017; 28:1768-1781. [PMID: 28468978 PMCID: PMC5491185 DOI: 10.1091/mbc.e16-06-0412] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 11/11/2022] Open
Abstract
The small GTPase RhoG and its exchange factor, Trio, regulate the formation and size of circular dorsal ruffles and associated functions, including macropinocytosis and cell migration. Circular dorsal ruffles (CDRs) are actin-rich structures that form on the dorsal surface of many mammalian cells in response to growth factor stimulation. CDRs represent a unique type of structure that forms transiently and only once upon stimulation. The formation of CDRs involves a drastic rearrangement of the cytoskeleton, which is regulated by the Rho family of GTPases. So far, only Rac1 has been consistently associated with CDR formation, whereas the role of other GTPases in this process is either lacking or inconclusive. Here we show that RhoG and its exchange factor, Trio, play a role in the regulation of CDR dynamics, particularly by modulating their size. RhoG is activated by Trio downstream of PDGF in a PI3K- and Src-dependent manner. Silencing RhoG expression decreases the number of cells that form CDRs, as well as the area of the CDRs. The regulation of CDR area by RhoG is independent of Rac1 function. In addition, our results show the RhoG plays a role in the cellular functions associated with CDR formation, including macropinocytosis, receptor internalization, and cell migration. Taken together, our results reveal a novel role for RhoG in the regulation of CDRs and the cellular processes associated with their formation.
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Affiliation(s)
- Alejandra Valdivia
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606.,Division of Cardiology, School of Medicine, Emory University, Atlanta, GA 30322
| | | | - Sahezeel Awadia
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Ashtyn Zinn
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Rafael Garcia-Mata
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
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16
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Goicoechea SM, Zinn A, Awadia SS, Snyder K, Garcia-Mata R. A RhoG-mediated signaling pathway that modulates invadopodia dynamics in breast cancer cells. J Cell Sci 2017; 130:1064-1077. [PMID: 28202690 DOI: 10.1242/jcs.195552] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 01/14/2017] [Indexed: 01/11/2023] Open
Abstract
One of the hallmarks of cancer is the ability of tumor cells to invade surrounding tissues and metastasize. During metastasis, cancer cells degrade the extracellular matrix, which acts as a physical barrier, by developing specialized actin-rich membrane protrusion structures called invadopodia. The formation of invadopodia is regulated by Rho GTPases, a family of proteins that regulates the actin cytoskeleton. Here, we describe a novel role for RhoG in the regulation of invadopodia disassembly in human breast cancer cells. Our results show that RhoG and Rac1 have independent and opposite roles in the regulation of invadopodia dynamics. We also show that SGEF (also known as ARHGEF26) is the exchange factor responsible for the activation of RhoG during invadopodia disassembly. When the expression of either RhoG or SGEF is silenced, invadopodia are more stable and have a longer lifetime than in control cells. Our findings also demonstrate that RhoG and SGEF modulate the phosphorylation of paxillin, which plays a key role during invadopodia disassembly. In summary, we have identified a novel signaling pathway involving SGEF, RhoG and paxillin phosphorylation, which functions in the regulation of invadopodia disassembly in breast cancer cells.
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Affiliation(s)
- Silvia M Goicoechea
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606, USA
| | - Ashtyn Zinn
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606, USA
| | - Sahezeel S Awadia
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606, USA
| | - Kyle Snyder
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606, USA
| | - Rafael Garcia-Mata
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606, USA
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17
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Schulz J, Franke K, Frick M, Schumacher S. Different roles of the small GTPases Rac1, Cdc42, and RhoG in CALEB/NGC-induced dendritic tree complexity. J Neurochem 2016; 139:26-39. [DOI: 10.1111/jnc.13735] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 06/24/2016] [Accepted: 07/08/2016] [Indexed: 12/01/2022]
Affiliation(s)
- Jana Schulz
- Institute of Molecular and Cellular Anatomy; Ulm University; Ulm Germany
| | - Kristin Franke
- Institute of Molecular and Cellular Anatomy; Ulm University; Ulm Germany
| | - Manfred Frick
- Institute of General Physiology; Ulm University; Ulm Germany
| | - Stefan Schumacher
- Institute of Molecular and Cellular Anatomy; Ulm University; Ulm Germany
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18
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Kalirin is required for BDNF-TrkB stimulated neurite outgrowth and branching. Neuropharmacology 2016; 107:227-238. [PMID: 27036892 DOI: 10.1016/j.neuropharm.2016.03.050] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 03/03/2016] [Accepted: 03/28/2016] [Indexed: 01/19/2023]
Abstract
Exogenous brain-derived neurotrophic factor (BDNF), acting through TrkB, is known to promote neurite formation and branching. This response to BDNF was eliminated by inhibition of TrkB kinase and by specific inhibition of the GEF1 domain of Kalirin, which activates Rac1. Neurons from Kalrn knockout mice were unable to activate Rac1 in response to BDNF. BDNF-triggered neurite outgrowth was abolished when Kalrn expression was reduced using shRNA that targets all of the major Kalrn isoforms, and reduced in neurons from Kalrn knockout mice. The Kalrn isoforms expressed early in development also include a GEF2 domain that activates RhoA. However, BDNF-stimulated neurite outgrowth in Kalrn knockout neurons was rescued by expression of Kalirin-7, which includes only the GEF1 domain but lacks the GEF2 domain. Dendritic morphogenesis, which requires spatially restricted, coordinated changes in the actin cytoskeleton and in the organization of microtubules, involves essential contributions from multiple Rho GEFs. Since Tiam1, another Rho GEF, is also required for BDNF-stimulated neurite outgrowth, an inhibitory fragment of Tiam1 (PHn-CC-EX) was tested and found to interfere with both Kalirin and Tiam1 GEF activity. The prolonged TrkB activation observed in response to BDNF in Kalrn knockout neurons and the altered time course and extent of ERK, CREB and Akt activation observed in the absence of Kalrn would be expected to alter the response of these neurons to other regulatory factors.
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19
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Hartmann H, Hoehne K, Rist E, Louw AM, Schlosshauer B. miR-124 disinhibits neurite outgrowth in an inflammatory environment. Cell Tissue Res 2015; 362:9-20. [DOI: 10.1007/s00441-015-2183-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/25/2015] [Indexed: 02/07/2023]
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20
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A role for Kalirin-7 in nociceptive sensitization via activity-dependent modulation of spinal synapses. Nat Commun 2015; 6:6820. [PMID: 25865668 PMCID: PMC4403379 DOI: 10.1038/ncomms7820] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/03/2015] [Indexed: 12/20/2022] Open
Abstract
Synaptic plasticity is the cornerstone of processes underlying persistent nociceptive activity-induced changes in normal nociceptive sensitivity. Kalirin-7 is a multifunctional guanine-nucleotide-exchange factor (GEF) for Rho GTPases that is characterized by its localization at excitatory synapses, interactions with glutamate receptors and its ability to dynamically modulate the neuronal cytoskeleton. Here we show that spinally expressed Kalirin-7 is required for persistent nociceptive activity-dependent synaptic long-term potentiation as well as activity-dependent remodelling of synaptic spines in the spinal dorsal horn, thereby orchestrating functional and structural plasticity during the course of inflammatory pain.
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21
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May V, Clason TA, Buttolph TR, Girard BM, Parsons RL. Calcium influx, but not intracellular calcium release, supports PACAP-mediated ERK activation in HEK PAC1 receptor cells. J Mol Neurosci 2014; 54:342-50. [PMID: 24723666 PMCID: PMC4194181 DOI: 10.1007/s12031-014-0300-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 03/28/2014] [Indexed: 01/10/2023]
Abstract
In HEK cells expressing GFP-tagged PAC1Hop1 receptors, PACAP augments ERK phosphorylation through two parallel pathways: one through PACAP/PAC1 receptor internalization/endosome MEK/ERK signaling and the other through PLC/DAG/PKC activation. We examined whether elevation of intracellular calcium ([Ca(2+)]i) was required for either of the PACAP/PAC1 receptor-mediated ERK activation mechanisms. The PACAP (25 nM)-induced elevation of [Ca(2+)]i was greater with cells maintained in Ca(2+)-containing than in Ca(2+)-deficient solution, suggesting that both calcium release from internal stores and calcium influx contributed to the rise in [Ca(2+)]i. A thapsigargin-induced increase in [Ca(2+)]i also was greater with calcium in the external solution. OAG, the cell permeable analogue of DAG, increased [Ca(2+)]i, but only in Ca(2+)-containing solution. Decreasing external calcium or depleting internal calcium stores did not block PACAP-induced PAC1 receptor internalization. Omission of calcium from the external solution, but not thapsigargin pretreatment, significantly blunted PACAP-stimulated ERK phosphorylation. The PKC inhibitor BimI decreased PACAP-mediated ERK activation in both Ca(2+)-containing or Ca(2+)-deficient solutions. In contrast, following Pitstop 2 pretreatment to block endocytic mechanisms, PACAP activated ERK only when calcium was present in the external solution. We conclude that the endosome signaling pathway is largely calcium-independent whereas calcium influx appears necessary for the PLC/DAG/PKC component of PACAP-induced ERK activation.
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Affiliation(s)
- Victor May
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, VT, 05405, USA
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22
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Bolton MM, Heaney CF, Murtishaw AS, Sabbagh JJ, Magcalas CM, Kinney JW. Postnatal alterations in GABA
B
receptor tone produce sensorimotor gating deficits and protein level differences in adulthood. Int J Dev Neurosci 2014; 41:17-27. [DOI: 10.1016/j.ijdevneu.2014.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/30/2014] [Accepted: 10/01/2014] [Indexed: 01/05/2023] Open
Affiliation(s)
- Monica M. Bolton
- Behavioral Neuroscience LaboratoryDepartment of PsychologyUniversity of NevadaLas VegasUnited States
| | - Chelcie F. Heaney
- Behavioral Neuroscience LaboratoryDepartment of PsychologyUniversity of NevadaLas VegasUnited States
| | - Andrew S. Murtishaw
- Behavioral Neuroscience LaboratoryDepartment of PsychologyUniversity of NevadaLas VegasUnited States
| | - Jonathan J. Sabbagh
- Behavioral Neuroscience LaboratoryDepartment of PsychologyUniversity of NevadaLas VegasUnited States
| | - Christy M. Magcalas
- Behavioral Neuroscience LaboratoryDepartment of PsychologyUniversity of NevadaLas VegasUnited States
| | - Jefferson W. Kinney
- Behavioral Neuroscience LaboratoryDepartment of PsychologyUniversity of NevadaLas VegasUnited States
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23
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Cai DC, Fonteijn H, Guadalupe T, Zwiers M, Wittfeld K, Teumer A, Hoogman M, Arias-Vásquez A, Yang Y, Buitelaar J, Fernández G, Brunner HG, van Bokhoven H, Franke B, Hegenscheid K, Homuth G, Fisher SE, Grabe HJ, Francks C, Hagoort P. A genome-wide search for quantitative trait loci affecting the cortical surface area and thickness of Heschl's gyrus. GENES BRAIN AND BEHAVIOR 2014; 13:675-85. [DOI: 10.1111/gbb.12157] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 07/10/2014] [Accepted: 07/24/2014] [Indexed: 12/21/2022]
Affiliation(s)
- D.-C. Cai
- Institute of Psychology; Chinese Academy of Sciences; Beijing China
- Max Planck Institute for Psycholinguistics
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Graduate University of Chinese Academy of Sciences; Beijing China
| | - H. Fonteijn
- Max Planck Institute for Psycholinguistics
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
| | | | - M. Zwiers
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - K. Wittfeld
- German Center for Neurodegenerative Diseases (DZNE), Rostock/Greifswald; Greifswald Germany
| | | | - M. Hoogman
- Max Planck Institute for Psycholinguistics
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - A. Arias-Vásquez
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - Y. Yang
- Institute of Psychology; Chinese Academy of Sciences; Beijing China
| | - J. Buitelaar
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - G. Fernández
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - H. G. Brunner
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - H. van Bokhoven
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | - B. Franke
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
- Departments of Human Genetics, Psychiatry and Cognitive Neuroscience; Radboud University Nijmegen Medical Centre; Nijmegen The Netherlands
| | | | - G. Homuth
- Interfaculty Institute for Genetics and Functional Genomics; University Medicine Greifswald; Greifswald
| | - S. E. Fisher
- Max Planck Institute for Psycholinguistics
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
| | - H. J. Grabe
- German Center for Neurodegenerative Diseases (DZNE), Rostock/Greifswald; Greifswald Germany
- Department of Psychiatry and Psychotherapy; University Medicine Greifswald, HELIOS Hospital Stralsund; Stralsund Germany
| | - C. Francks
- Max Planck Institute for Psycholinguistics
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
| | - P. Hagoort
- Max Planck Institute for Psycholinguistics
- Donders Institute for Brain, Cognition and Behaviour; Radboud University Nijmegen; Nijmegen The Netherlands
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24
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Dynamic Microtubules Catalyze Formation of Navigator-TRIO Complexes to Regulate Neurite Extension. Curr Biol 2014; 24:1778-85. [DOI: 10.1016/j.cub.2014.06.037] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 05/07/2014] [Accepted: 06/13/2014] [Indexed: 01/22/2023]
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25
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May V, Buttolph TR, Girard BM, Clason TA, Parsons RL. PACAP-induced ERK activation in HEK cells expressing PAC1 receptors involves both receptor internalization and PKC signaling. Am J Physiol Cell Physiol 2014; 306:C1068-79. [PMID: 24696141 DOI: 10.1152/ajpcell.00001.2014] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The pituitary adenylate cyclase-activating polypeptide (PACAP)-selective PAC1 receptor (Adcyap1r1) is a G protein-coupled receptor (GPCR) that activates adenylyl cyclase and PLC. Similar to many other GPCRs, our previous studies showed that the PAC1 receptor is internalized after ligand binding to form signaling endosomes, which recruit additional second messenger pathways. Using a human embryonic kidney (HEK 293) PAC1Hop1-EGFP receptor cell line, we have examined how different PAC1 receptor signaling mechanisms contribute to MEK/ERK activation. Unlike PAC1 receptor-stimulated adenylyl cyclase/cAMP production in the plasma membrane, PACAP-mediated ERK phosphorylation was partly dependent on receptor internalization, as determined by treatment with pharmacological inhibitors of endocytosis or temperature reduction, which also suppressed receptor internalization. Stimulation of cAMP generation by forskolin or exposure to the cell-permeable cAMP analogs 8-bromo-cAMP and dibutyryl cAMP had minimal effects on ERK phosphorylation in this system. The ability of reduced temperature (24°C) to consistently suppress ERK activation to a greater extent than the endocytosis inhibitors Pitstop 2 and dynasore indicated that other mechanisms, in addition to PAC1 internalization/endosome activation, were involved. Inhibition of PAC1 receptor-stimulated PLC/diacylglycerol/PKC signaling by bisindoylmaleimide I also attenuated ERK phosphorylation, and direct PKC activation with phorbol ester increased ERK phosphorylation in a temperature-dependent manner. Inhibition of PAC1 receptor endocytosis and PKC activation completely blocked PACAP-stimulated ERK activation. PACAP augmented phosphorylated ERK staining uniformly over the cytoplasm and nucleus, and PKC signaling facilitated nuclear phosphorylated ERK translocation. In sum, our results show that PACAP/PAC1 receptor endocytosis and PLC/diacylglycerol/PKC activation represent two complementary mechanisms contributing to PACAP-induced ERK activation.
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Affiliation(s)
- Victor May
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Thomas R Buttolph
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Beatrice M Girard
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Todd A Clason
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
| | - Rodney L Parsons
- Department of Neurological Sciences, College of Medicine, University of Vermont, Burlington, Vermont
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26
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Abstract
Development of the nervous system requires efficient extension and guidance of axons and dendrites culminating in synapse formation. Axonal growth and navigation during embryogenesis are controlled by extracellular cues. Many of the same extracellular signals also regulate axonal branching. The emergence of collateral branches from the axon augments the complexity of nervous system innervation and provides an additional mechanism for target selection. Rho-family GTPases play an important role in regulating intracellular cytoskeletal and signaling pathways that facilitate axonal morphological changes. RhoA/G and Rac1 GTPase functions are complex and they can induce or inhibit branch formation, depending on neuronal type, cell context or signaling mechanisms. Evidence of a role of Cdc42 in axon branching is mostly lacking. In contrast, Rac3 has thus far been implicated in the regulation of axon branching. Future analysis of the upstream regulators and downstream effectors mediating the effects of Rho-family GTPase will provide insights into the cellular processes effected, and shed light on the sometimes opposing roles of these GTPases in the regulation of axon branching.
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Affiliation(s)
- Mirela Spillane
- Shriners Hospitals Pediatric Research Center; Center for Neural Repair and Rehabilitation; Temple University; Department of Anatomy and Cell Biology; Philadelphia, PA USA
| | - Gianluca Gallo
- Shriners Hospitals Pediatric Research Center; Center for Neural Repair and Rehabilitation; Temple University; Department of Anatomy and Cell Biology; Philadelphia, PA USA
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Kiraly DD, Nemirovsky NE, LaRese TP, Tomek SE, Yahn SL, Olive MF, Eipper BA, Mains RE. Constitutive knockout of kalirin-7 leads to increased rates of cocaine self-administration. Mol Pharmacol 2013; 84:582-90. [PMID: 23894151 PMCID: PMC3781382 DOI: 10.1124/mol.113.087106] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 07/26/2013] [Indexed: 01/01/2023] Open
Abstract
Kalirin-7 (Kal7) is a Rho-guanine nucleotide exchange factor that is localized in neuronal postsynaptic densities. Kal7 interacts with the NR2B subunit of the NMDA receptor and regulates aspects of dendritic spine dynamics both in vitro and in vivo. Chronic treatment with cocaine increases dendritic spine density in the nucleus accumbens (NAc) of rodents and primates. Kal7 mRNA and protein are upregulated in the NAc following cocaine treatment, and the presence of Kal7 is necessary for the normal proliferation of dendritic spines following cocaine use. Mice that constitutively lack Kal7 [Kalirin-7 knockout mice (Kal7(KO))] demonstrate increased locomotor sensitization to cocaine and a decreased place preference for cocaine. Here, using an intravenous cocaine self-administration paradigm, Kal7(KO) mice exhibit increased administration of cocaine at lower doses as compared with wild-type (Wt) mice. Analyses of mRNA transcript levels from the NAc of mice that self-administered saline or cocaine reveal that larger splice variants of the Kalrn gene are increased by cocaine more dramatically in Kal7(KO) mice than in Wt mice. Additionally, transcripts encoding the NR2B subunit of the NMDA receptor increased in Wt mice that self-administered cocaine but were unchanged in similarly experienced Kal7(KO) mice. These findings suggest that Kal7 participates in the reinforcing effects of cocaine, and that Kal7 and cocaine interact to alter the expression of genes related to critical glutamatergic signaling pathways in the NAc.
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Affiliation(s)
- Drew D Kiraly
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut (D.D.K., T.P.L., B.A.E., R.E.M.); and Department of Psychology, Program in Behavioral Neuroscience (N.E.N., S.E.T., S.L.Y., M.F.O.) and Interdisciplinary Graduate Program in Neuroscience (M.F.O.), Arizona State University, Tempe, Arizona
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Cheung HNM, Dunbar C, Mórotz GM, Cheng WH, Chan HYE, Miller CCJ, Lau KF. FE65 interacts with ADP-ribosylation factor 6 to promote neurite outgrowth. FASEB J 2013; 28:337-49. [PMID: 24056087 DOI: 10.1096/fj.13-232694] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
FE65 is an adaptor protein that binds to the amyloid precursor protein (APP). As such, FE65 has been implicated in the pathogenesis of Alzheimer's disease. In addition, evidence suggests that FE65 is involved in brain development. It is generally believed that FE65 participates in these processes by recruiting various interacting partners to form functional complexes. Here, we show that via its first phosphotyrosine binding (PTB) domain, FE65 binds to the small GTPase ADP-ribosylation factor 6 (ARF6). FE65 preferentially binds to ARF6-GDP, and they colocalize in neuronal growth cones. Interestingly, FE65 stimulates the activation of both ARF6 and its downstream GTPase Rac1, a regulator of actin dynamics, and functions in growth cones to stimulate neurite outgrowth. We show that transfection of FE65 and/or ARF6 promotes whereas small interfering RNA knockdown of FE65 or ARF6 inhibits neurite outgrowth in cultured neurons as compared to the mock-transfected control cells. Moreover, knockdown of ARF6 attenuates FE65 stimulation of neurite outgrowth and defective neurite outgrowth seen in FE65-deficient neurons is partially corrected by ARF6 overexpression. Notably, the stimulatory effect of FE65 and ARF6 on neurite outgrowth is abrogated either by dominant-negative Rac1 or knockdown of Rac1. Thus, we identify FE65 as a novel regulator of neurite outgrowth via controlling ARF6-Rac1 signaling.
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Affiliation(s)
- Hei Nga Maggie Cheung
- 1School of Life Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
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29
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Miller MB, Yan Y, Eipper BA, Mains RE. Neuronal Rho GEFs in synaptic physiology and behavior. Neuroscientist 2013; 19:255-73. [PMID: 23401188 DOI: 10.1177/1073858413475486] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the mammalian brain, the majority of excitatory synapses are housed in micron-sized dendritic protrusions called spines, which can undergo rapid changes in shape and number in response to increased or decreased synaptic activity. These dynamic alterations in dendritic spines require precise control of the actin cytoskeleton. Within spines, multidomain Rho guanine nucleotide exchange factors (Rho GEFs) coordinate activation of their target Rho GTPases by a variety of pathways. In this review, we focus on the handful of disease-related Rho GEFs (Kalirin; Trio; Tiam1; P-Rex1,2; RasGRF1,2; Collybistin) localized at synapses and known to affect electrophysiology, spine morphology, and animal behavior. The goal is to integrate structure/function studies with measurements of synaptic function and behavioral phenotypes in animal models.
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Affiliation(s)
- Megan B Miller
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401, USA
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30
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Abstract
RhoG is a member of the Rho family of small GTPases sharing highest sequence similarity with Rac and Cdc42. Mig-2 and Mtl represent the functional equivalents of RhoG in Caenorhabditis elegans and Drosophila, respectively. RhoG has attracted great interest because it plays a central role in the regulation of cytoskeletal reorganization in various physiological and pathophysiological situations. For example, it is fundamental to phagocytotic processes, is able to regulate gene expression, cell survival and proliferation, and is involved in cell migration and in the invasion of pathogenic bacteria. The activation of Rac1 via an ELMO/Dock180 module has been elaborated to be important for RhoG signaling. Although a stimulatory role for neurite outgrowth in the pheochromocytoma PC12 cell line has been assigned to RhoG, the exact function of this GTPase for the development of the processes of primary neurons remains to be clarified. In this view, we discuss the impact of RhoG on axonal and dendritic differentiation, its role as a conductor of Rac1 and Cdc42 activity and the functional regulation of RhoG expression by the microRNA miR-124.
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Affiliation(s)
- Stefan Schumacher
- Institute of Molecular and Cellular Anatomy, Ulm University, Ulm, Germany.
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31
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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.
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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:
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Mandela P, Yankova M, Conti LH, Ma XM, Grady J, Eipper BA, Mains RE. Kalrn plays key roles within and outside of the nervous system. BMC Neurosci 2012; 13:136. [PMID: 23116210 PMCID: PMC3541206 DOI: 10.1186/1471-2202-13-136] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 10/22/2012] [Indexed: 11/23/2022] Open
Abstract
Background The human KALRN gene, which encodes a complex, multifunctional Rho GDP/GTP exchange factor, has been linked to cardiovascular disease, psychiatric disorders and neurodegeneration. Examination of existing Kalrn knockout mouse models has focused only on neuronal phenotypes. However, Kalirin was first identified through its interaction with an enzyme involved in the synthesis and secretion of multiple bioactive peptides, and studies in C.elegans revealed roles for its orthologue in neurosecretion. Results We used a broad array of tests to evaluate the effects of ablating a single exon in the spectrin repeat region of Kalrn (KalSRKO/KO); transcripts encoding Kalrn isoforms containing only the second GEF domain can still be produced from the single remaining functional Kalrn promoter. As expected, KalSRKO/KO mice showed a decrease in anxiety-like behavior and a passive avoidance deficit. No changes were observed in prepulse inhibition of acoustic startle or tests of depression-like behavior. Growth rate, parturition and pituitary secretion of growth hormone and prolactin were deficient in the KalSRKO/KO mice. Based on the fact that a subset of Kalrn isoforms is expressed in mouse skeletal muscle and the observation that muscle function in C.elegans requires its Kalrn orthologue, KalSRKO/KO mice were evaluated in the rotarod and wire hang tests. KalSRKO/KO mice showed a profound decrease in neuromuscular function, with deficits apparent in KalSR+/KO mice; these deficits were not as marked when loss of Kalrn expression was restricted to the nervous system. Pre- and postsynaptic deficits in the neuromuscular junction were observed, along with alterations in sarcomere length. Conclusions Many of the widespread and diverse deficits observed both within and outside of the nervous system when expression of Kalrn is eliminated may reflect its role in secretory granule function and its expression outside of the nervous system.
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Affiliation(s)
- Prashant Mandela
- Department of Neuroscience, University of Connecticut Health Science Center, Farmington, CT 06030-3401, USA
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33
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Ma XM, Huang JP, Xin X, Yan Y, Mains RE, Eipper BA. A role for kalirin in the response of rat medium spiny neurons to cocaine. Mol Pharmacol 2012; 82:738-45. [PMID: 22828798 DOI: 10.1124/mol.112.080044] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Kalirin-7 (Kal7), the major kalirin isoform in adult brain, plays a key role in the formation of dendritic spines in hippocampal/cortical neurons. Its role in the GABAergic medium spiny neurons (MSNs) of the nucleus accumbens (NAc) and striatum, the areas known to play a key role in the common reward pathway, is not as well understood. Although Kal7 expression in mouse NAc increased in response to cocaine, MSN dendritic spine density did not differ from that for the wild type in Kal7-null mice. Unlike wild-type mice, Kal7-null mice did not respond to cocaine with an increase in MSN dendritic spine density. To explore further the role of Kal7 in cocaine-induced alterations in MSN morphology, we turned to the rat. Based on immunostaining, both Kal7 and Kal12 are expressed at moderate levels in the MSNs of the NAc and striatum. Expression of Kal7 and Kal12 in MSNs of both areas increases after repeated cocaine treatments. Overexpression of Kal7 in cultured MSN neurons increases dendritic spine density, as observed in rats after long-term cocaine administration. Reducing endogenous expression of all major kalirin isoforms in cultured MSN neurons causes a decrease in total dendritic length and dendritic spine density. These data suggest that kalirin is essential for maintaining spine density in NAc MSNs under normal conditions and that Kal7 is an obligatory intermediate in the response of MSNs to repeated exposure to cocaine.
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Affiliation(s)
- Xin-Ming Ma
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Ave., MC-3401, Farmington, CT, USA.
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Gonzalez-Billault C, Muñoz-Llancao P, Henriquez DR, Wojnacki J, Conde C, Caceres A. The role of small GTPases in neuronal morphogenesis and polarity. Cytoskeleton (Hoboken) 2012; 69:464-85. [PMID: 22605667 DOI: 10.1002/cm.21034] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 04/12/2012] [Accepted: 04/16/2012] [Indexed: 12/21/2022]
Abstract
The highly dynamic remodeling and cross talk of the microtubule and actin cytoskeleton support neuronal morphogenesis. Small RhoGTPases family members have emerged as crucial regulators of cytoskeletal dynamics. In this review we will comprehensively analyze findings that support the participation of RhoA, Rac, Cdc42, and TC10 in different neuronal morphogenetic events ranging from migration to synaptic plasticity. We will specifically address the contribution of these GTPases to support neuronal polarity and axonal elongation.
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Affiliation(s)
- Christian Gonzalez-Billault
- Faculty of Sciences, Laboratory of Cell and Neuronal Dynamics, Department of Biology and Institute for Cell Dynamics and Biotechnology, Universidad de Chile, Santiago, Chile.
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35
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miR-124-regulated RhoG reduces neuronal process complexity via ELMO/Dock180/Rac1 and Cdc42 signalling. EMBO J 2012; 31:2908-21. [PMID: 22588079 DOI: 10.1038/emboj.2012.130] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/05/2012] [Indexed: 12/19/2022] Open
Abstract
The small GTPase RhoG plays a central role in actin remodelling during diverse biological processes such as neurite outgrowth, cell migration, phagocytosis of apoptotic cells, and the invasion of pathogenic bacteria. Although it is known that RhoG stimulates neurite outgrowth in the rat pheochromocytoma PC12 cell line, neither the physiological function nor the regulation of this GTPase in neuronal differentiation is clear. Here, we identify RhoG as an inhibitor of neuronal process complexity, which is regulated by the microRNA miR-124. We find that RhoG inhibits dendritic branching in hippocampal neurons in vitro and in vivo. RhoG also inhibits axonal branching, acting via an ELMO/Dock180/Rac1 signalling pathway. However, RhoG inhibits dendritic branching dependent on the small GTPase Cdc42. Finally, we show that the expression of RhoG in neurons is suppressed by the CNS-specific microRNA miR-124 and connect the regulation of RhoG expression by miR-124 to the stimulation of neuronal process complexity. Thus, RhoG emerges as a cellular conductor of Rac1 and Cdc42 activity, in turn regulated by miR-124 to control axonal and dendritic branching.
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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.
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Affiliation(s)
- Patrick S Murray
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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37
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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.
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Ephexin4 and EphA2 mediate resistance to anoikis through RhoG and phosphatidylinositol 3-kinase. Exp Cell Res 2011; 317:1701-13. [PMID: 21621533 DOI: 10.1016/j.yexcr.2011.05.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 04/28/2011] [Accepted: 05/13/2011] [Indexed: 12/22/2022]
Abstract
Disruption of cell-extracellular matrix interaction causes epithelial cells to undergo apoptosis called anoikis, and resistance to anoikis has been suggested to be a critical step for cancer cells to metastasize. EphA2 is frequently overexpressed in a variety of human cancers, and recent studies have found that overexpression of EphA2 contributes to malignant cellular behavior, including resistance to anoikis, in several different types of cancer cells. Here we show that Ephexin4, a guanine nucleotide exchange factor for the small GTPase RhoG that interacts with EphA2, plays an important role in the regulation of anoikis. Knockdown of Ephexin4 promoted anoikis in HeLa cells, and experiments using a knockdown-rescue approach showed that activation of RhoG, phosphatidylinositol 3-kinase (PI3K), and Akt was required for the Ephexin4-mediated suppression of anoikis. Indeed, Ephexin4 knockdown caused a decrease in RhoG activity and Akt phosphorylation in HeLa cells cultured in suspension. In addition, Ephexin4 was involved in the EphA2-mediated suppression of anoikis. Taken together, these results suggest that Ephexin4 mediates resistance to anoikis through activation of RhoG and PI3K downstream of EphA2.
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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.
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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
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40
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Kiraly DD, Eipper-Mains JE, Mains RE, Eipper BA. Synaptic plasticity, a symphony in GEF. ACS Chem Neurosci 2010; 1:348-365. [PMID: 20543890 DOI: 10.1021/cn100012x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dendritic spines are the postsynaptic sites for the majority of excitatory synapses in the mammalian forebrain. While many spines display great stability, others change shape in a matter of seconds to minutes. These rapid alterations in dendritic spine number and size require tight control of the actin cytoskeleton, the main structural component of dendritic spines. The ability of neurons to alter spine number and size is essential for the expression of neuronal plasticity. Within spines, guanine nucleotide exchange factors (GEFs) act as critical regulators of the actin cytoskeleton by controlling the activity of Rho-GTPases. In this review we focus on the Rho-GEFs expressed in the nucleus accumbens and localized to the postsynaptic density, and thus positioned to effect rapid alterations in the structure of dendritic spines. We review literature that ties these GEFs to different receptor systems and intracellular signaling cascades and discuss the effects these interactions are likely to have on synaptic plasticity.
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Affiliation(s)
- Drew D. Kiraly
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Jodi E. Eipper-Mains
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, Connecticut
| | - Richard E. Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
| | - Betty A. Eipper
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut
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Samson T, Welch C, Monaghan-Benson E, Hahn KM, Burridge K. Endogenous RhoG is rapidly activated after epidermal growth factor stimulation through multiple guanine-nucleotide exchange factors. Mol Biol Cell 2010; 21:1629-42. [PMID: 20237158 PMCID: PMC2861620 DOI: 10.1091/mbc.e09-09-0809] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In this article it is shown that EGF stimulation leads to rapid activation of RhoG through Vav GEFs and the GEF PLEKHG6. Importantly, different cellular responses induced by EGF are determined by the available GEFs. Furthermore, this article presents results showing that EGF-stimulated cell migration and EGFR internalization are regulated by RhoG. RhoG is a member of the Rac-like subgroup of Rho GTPases and has been linked to a variety of different cellular functions. Nevertheless, many aspects of RhoG upstream and downstream signaling remain unclear; in particular, few extracellular stimuli that modulate RhoG activity have been identified. Here, we describe that stimulation of epithelial cells with epidermal growth factor leads to strong and rapid activation of RhoG. Importantly, this rapid activation was not observed with other growth factors tested. The kinetics of RhoG activation after epidermal growth factor (EGF) stimulation parallel the previously described Rac1 activation. However, we show that both GTPases are activated independently of one another. Kinase inhibition studies indicate that the rapid activation of RhoG and Rac1 after EGF treatment requires the activity of the EGF receptor kinase, but neither phosphatidylinositol 3-kinase nor Src kinases. By using nucleotide-free RhoG pull-down assays and small interfering RNA-mediated knockdown studies, we further show that guanine-nucleotide exchange factors (GEFs) of the Vav family mediate EGF-induced rapid activation of RhoG. In addition, we found that in certain cell types the recently described RhoG GEF PLEKHG6 can also contribute to the rapid activation of RhoG after EGF stimulation. Finally, we present results that show that RhoG has functions in EGF-stimulated cell migration and in regulating EGF receptor internalization.
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Affiliation(s)
- Thomas Samson
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
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May V, Lutz E, MacKenzie C, Schutz KC, Dozark K, Braas KM. Pituitary adenylate cyclase-activating polypeptide (PACAP)/PAC1HOP1 receptor activation coordinates multiple neurotrophic signaling pathways: Akt activation through phosphatidylinositol 3-kinase gamma and vesicle endocytosis for neuronal survival. J Biol Chem 2010; 285:9749-9761. [PMID: 20093365 PMCID: PMC2843224 DOI: 10.1074/jbc.m109.043117] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
MAPK and Akt pathways are predominant mediators of trophic signaling for many neuronal systems. Among the vasoactive intestinal peptide/secretin/glucagon family of related peptides, pituitary adenylate cyclase-activating polypeptide (PACAP) binding to specific PAC(1) receptor isoforms can engage multiple signaling pathways and promote neuroprotection through mechanisms that are not well understood. Using a primary sympathetic neuronal system, the current studies demonstrate that PACAP activation of PAC(1)HOP1 receptors engages both MAPK and Akt neurotrophic pathways in an integrated program to facilitate neuronal survival after growth factor withdrawal. PACAP not only stimulated prosurvival ERK1/2 and ERK5 activation but also abrogated SAPK/JNK and p38 MAPK signaling in parallel. In contrast to the potent and rapid effects of PACAP in ERK1/2 phosphorylation, PACAP stimulated Akt phosphorylation in a late phase of PAC(1)HOP1 receptor signaling. From inhibitor and immunoprecipitation analyses, the PACAP/PAC(1)HOP1 receptor-mediated Akt responses did not represent transactivation mechanisms but appeared to depend on G alpha(q)/phosphatidylinositol 3-kinase gamma activity and vesicular internalization pathways. Phosphatidylinositol 3-kinase gamma-selective inhibitors blocked PACAP-stimulated Akt phosphorylation in primary neuronal cultures and in PAC(1)HOP1-overexpressing cell lines; RNA interference-mediated knockdown of the receptor effectors attenuated PACAP-mediated Akt activation. Similarly, perturbation of endocytic pathways also blocked Akt phosphorylation. Between ERK and Akt pathways, PACAP-stimulated Akt signaling was the primary cascade that attenuated cultured neuron apoptosis after growth factor withdrawal. The partitioning of PACAP-mediated Akt signaling in endosomes may be a key mechanism contributing to the high spatial and temporal specificity in signal transduction necessary for survival pathways.
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Affiliation(s)
- Victor May
- Departments of Anatomy and Neurobiology and of Pharmacology, The University of Vermont College of Medicine, Burlington, Vermont 05405.
| | - Eve Lutz
- University of Strathclyde, Strathclyde Institute of Pharmacy and Biomedical Sciences, Royal College, 204 George Street, Glasgow G1 1XW, Scotland, United Kingdom
| | - Christopher MacKenzie
- University of Strathclyde, Strathclyde Institute of Pharmacy and Biomedical Sciences, Royal College, 204 George Street, Glasgow G1 1XW, Scotland, United Kingdom
| | - Kristin C Schutz
- Departments of Anatomy and Neurobiology and of Pharmacology, The University of Vermont College of Medicine, Burlington, Vermont 05405
| | - Kate Dozark
- Departments of Anatomy and Neurobiology and of Pharmacology, The University of Vermont College of Medicine, Burlington, Vermont 05405
| | - Karen M Braas
- Departments of Anatomy and Neurobiology and of Pharmacology, The University of Vermont College of Medicine, Burlington, Vermont 05405
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Fujimoto S, Negishi M, Katoh H. RhoG promotes neural progenitor cell proliferation in mouse cerebral cortex. Mol Biol Cell 2009; 20:4941-50. [PMID: 19812248 DOI: 10.1091/mbc.e09-03-0200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In early cortical development, neural progenitor cells (NPCs) expand their population in the ventricular zone (VZ), and produce neurons. Although a series of studies have revealed the process of neurogenesis, the molecular mechanisms regulating NPC proliferation are still largely unknown. Here we found that RhoG, a member of Rho family GTPases, was expressed in the VZ at early stages of cortical development. Expression of constitutively active RhoG promoted NPC proliferation and incorporation of bromodeoxyuridine (BrdU) in vitro, and the proportion of Ki67-positive cells in vivo. In contrast, knockdown of RhoG by RNA interference suppressed the proliferation, BrdU incorporation, and the proportion of Ki67-positive cells in NPCs. However, knockdown of RhoG did not affect differentiation and survival of NPC. The RhoG-induced promotion of BrdU incorporation required phosphatidylinositol 3-kinase (PI3K) activity but not the interaction with ELMO. Taken together, these results indicate that RhoG promotes NPC proliferation through PI3K in cortical development.
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Affiliation(s)
- Satoshi Fujimoto
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Sharma AK, Searfoss GH, Reams RY, Jordan WH, Snyder PW, Chiang AY, Jolly RA, Ryan TP. Kainic Acid-induced F-344 Rat model of Mesial Temporal Lobe Epilepsy: Gene Expression and Canonical Pathways. Toxicol Pathol 2009; 37:776-89. [DOI: 10.1177/0192623309344202] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Mesial temporal lobe epilepsy (MTLE) is a severe neurological condition of unknown pathogenesis for which several animal models have been developed. To obtain a better understanding of the underlying molecular mechanisms and identify potential biomarkers of lesion progression, we used a rat kainic acid (KA) treatment model of MTLE coupled with global gene expression analysis to examine temporal (four hours, days 3, 14, or 28) gene regulation relative to hippocampal histopathological changes. The authors recommend reviewing the companion histopathology paper ( Sharma et al. 2008 ) to get a better understanding of the work presented here. Analysis of filtered gene expression data using Ingenuity Pathways Analysis (Ingenuity Systems, http://www.ingenuity.com ) revealed that a number of genes pertaining to neuronal plasticity (RhoA, Rac1, Cdc42, BDNF, and Trk), neurodegeneration (Caspase3, Calpain 1, Bax, a Cytochrome c, and Smac/Diablo), and inflammation/immune-response pathways (TNF-α, CCL2, Cox2) were modulated in a temporal fashion after KA treatment. Expression changes for selected genes known to have a role in neuronal plasticity were subsequently validated by quantitative polymerase chain reaction (qPCR). Notably, canonical pathway analysis revealed that a number of genes within the axon guidance signaling canonical pathway were up-regulated from Days 3 to 28, which correlated with aberrant mossy fiber (MF) sprouting observed histologically beginning at Day 6. Importantly, analysis of the gene expression data also identified potential biomarkers for monitoring neurodegeneration (Cox2) and neuronal/synaptic plasticity (Kalrn).
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Affiliation(s)
- Alok K. Sharma
- Department of Pathology, Covance Laboratories Inc., Madison, WI 53704, USA
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
| | - George H. Searfoss
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN 46285, USA
| | - Rachel Y. Reams
- Department of Pathology, Covance Laboratories Inc., Greenfield, IN 46140, USA
| | - William H. Jordan
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN 46285, USA
| | - Paul W. Snyder
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
| | - Alan Y. Chiang
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN 46285, USA
| | - Robert A. Jolly
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN 46285, USA
| | - Timothy P. Ryan
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN 46285, USA
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Ueda S, Fujimoto S, Hiramoto K, Negishi M, Katoh H. Dock4 regulates dendritic development in hippocampal neurons. J Neurosci Res 2009; 86:3052-61. [PMID: 18615735 DOI: 10.1002/jnr.21763] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Dendrite development is required for establishing proper neuronal connectivity. Rho-family small GTPases have been reported to play important roles in the regulation of dendritic growth and morphology. However, the molecular mechanisms that control the activities of Rho GTPases in developing dendrites are not well understood. In the present study we found Dock4, an activator of the small GTPase Rac, to have a role in regulating dendritic growth and branching in rat hippocampal neurons. Dock4 is highly expressed in the developing rat brain, predominantly in hippocampal neurons. In dissociated cultured hippocampal neurons, the expression of Dock4 protein is up-regulated after between 3 and 8 days in culture, when dendrites begin to grow. Knockdown of endogenous Dock4 results in reduced dendritic growth and branching. Conversely, overexpression of Dock4 with its binding partner ELMO2 enhances the numbers of dendrites and dendritic branches. These morphological effects elicited by Dock4 and ELMO2 require Rac activation and the C-terminal Crk-binding region of Dock4. Indeed, Dock4 forms a complex with ELMO2 and CrkII in hippocampal neurons. These findings demonstrate a new function of the Rac activator Dock4 in dendritic morphogenesis in hippocampal neurons.
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Affiliation(s)
- Shuhei Ueda
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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Heasman SJ, Ridley AJ. Mammalian Rho GTPases: new insights into their functions from in vivo studies. Nat Rev Mol Cell Biol 2008; 9:690-701. [PMID: 18719708 DOI: 10.1038/nrm2476] [Citation(s) in RCA: 1434] [Impact Index Per Article: 89.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Rho GTPases are key regulators of cytoskeletal dynamics and affect many cellular processes, including cell polarity, migration, vesicle trafficking and cytokinesis. These proteins are conserved from plants and yeast to mammals, and function by interacting with and stimulating various downstream targets, including actin nucleators, protein kinases and phospholipases. The roles of Rho GTPases have been extensively studied in different mammalian cell types using mainly dominant negative and constitutively active mutants. The recent availability of knockout mice for several members of the Rho family reveals new information about their roles in signalling to the cytoskeleton and in development.
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Affiliation(s)
- Sarah J Heasman
- Randall Division of Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK.
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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.
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Affiliation(s)
- Xiaonan Xin
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3401, USA
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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.
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Affiliation(s)
- Martin R Schiller
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA.
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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: 71] [Impact Index Per Article: 4.4] [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.
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Affiliation(s)
- Ivan de Curtis
- Cell Adhesion Unit, San Raffaele Scientific Institute, Milan, Italy.
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D'Angelo R, Aresta S, Blangy A, Del Maestro L, Louvard D, Arpin M. Interaction of ezrin with the novel guanine nucleotide exchange factor PLEKHG6 promotes RhoG-dependent apical cytoskeleton rearrangements in epithelial cells. Mol Biol Cell 2007; 18:4780-93. [PMID: 17881735 PMCID: PMC2096603 DOI: 10.1091/mbc.e06-12-1144] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 07/18/2006] [Accepted: 09/11/2007] [Indexed: 01/12/2023] Open
Abstract
The mechanisms underlying functional interactions between ERM (ezrin, radixin, moesin) proteins and Rho GTPases are not well understood. Here we characterized the interaction between ezrin and a novel Rho guanine nucleotide exchange factor, PLEKHG6. We show that ezrin recruits PLEKHG6 to the apical pole of epithelial cells where PLEKHG6 induces the formation of microvilli and membrane ruffles. These morphological changes are inhibited by dominant negative forms of RhoG. Indeed, we found that PLEKHG6 activates RhoG and to a much lesser extent Rac1. In addition we show that ezrin forms a complex with PLEKHG6 and RhoG. Furthermore, we detected a ternary complex between ezrin, PLEKHG6, and the RhoG effector ELMO. We demonstrate that PLEKHG6 and ezrin are both required in macropinocytosis. After down-regulation of either PLEKHG6 or ezrin expression, we observed an inhibition of dextran uptake in EGF-stimulated A431 cells. Altogether, our data indicate that ezrin allows the local activation of RhoG at the apical pole of epithelial cells by recruiting upstream and downstream regulators of RhoG and that both PLEKHG6 and ezrin are required for efficient macropinocytosis.
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Affiliation(s)
- Romina D'Angelo
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris 75248, France
- Institut Curie, Centre de Recherche, Paris 75248, France
| | | | - Anne Blangy
- Centre National de la Recherche Scientifique, Centre de Recherche de Biochimie Macromoléculaire, 34293 Montpellier Cedex 5, France
| | - Laurence Del Maestro
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris 75248, France
- Institut Curie, Centre de Recherche, Paris 75248, France
| | - Daniel Louvard
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris 75248, France
- Institut Curie, Centre de Recherche, Paris 75248, France
| | - Monique Arpin
- *Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, Paris 75248, France
- Institut Curie, Centre de Recherche, Paris 75248, France
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