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Yonemura Y, Sakai Y, Nakata R, Hagita-Tatsumoto A, Miyasaka T, Misonou H. Active Transport by Cytoplasmic Dynein Maintains the Localization of MAP2 in Developing Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.26.538370. [PMID: 37163107 PMCID: PMC10168327 DOI: 10.1101/2023.04.26.538370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
MAP2 has been widely used as a marker of neuronal dendrites because of its extensive restriction in the somatodendritic region of neurons. Despite that, how the precise localization of such a soluble protein is established and maintained against thermal forces and diffusion has been elusive and long remained a mystery in neuroscience. In this study, we aimed to uncover the mechanism behind how MAP2 is retained in the somatodendritic region. Using GFP-tagged MAP2 expressed in cultured hippocampal neurons, we discovered a crucial protein region responsible for the localization of MAP2, the serine/proline-rich (S/P) region. Our pulse-chase live-cell imaging revealed the slow but steady migration of MAP2 toward distal dendrites, which was not observed in a MAP2 mutant lacking the S/P region, indicating that S/P-dependent transport is vital for the proper localization of MAP2. Furthermore, our experiments using an inhibitor of cytoplasmic Dynein, ciliobrevin D, as well as Dynein knockdown, showed that cytoplasmic Dynein is involved in the transport of MAP2 in dendrites. We also found that Dynein complex binds to MAP2 through the S/P region in heterologous cells. Using mathematical modeling based on experimental data, we confirmed that an intermittent active transport mechanism is essential. Thus, we propose that the cytoplasmic Dynein recruits and transports free MAP2 toward distal dendrites, thereby maintaining the precise dendritic localization of MAP2 in neurons. Our findings shed light on the previously unknown mechanism behind MAP2 localization and provide a new direction for soluble protein trafficking research in the field of cell biology of neurons.
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2
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Kounoupa Z, Tivodar S, Theodorakis K, Kyriakis D, Denaxa M, Karagogeos D. Rac1 and Rac3 GTPases and TPC2 are required for axonal outgrowth and migration of cortical interneurons. J Cell Sci 2023; 136:286920. [PMID: 36744839 DOI: 10.1242/jcs.260373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 01/31/2023] [Indexed: 02/07/2023] Open
Abstract
Rho GTPases, among them Rac1 and Rac3, are major transducers of extracellular signals and are involved in multiple cellular processes. In cortical interneurons, the neurons that control the balance between excitation and inhibition of cortical circuits, Rac1 and Rac3 are essential for their development. Ablation of both leads to a severe reduction in the numbers of mature interneurons found in the murine cortex, which is partially due to abnormal cell cycle progression of interneuron precursors and defective formation of growth cones in young neurons. Here, we present new evidence that upon Rac1 and Rac3 ablation, centrosome, Golgi complex and lysosome positioning is significantly perturbed, thus affecting both interneuron migration and axon growth. Moreover, for the first time, we provide evidence of altered expression and localization of the two-pore channel 2 (TPC2) voltage-gated ion channel that mediates Ca2+ release. Pharmacological inhibition of TPC2 negatively affected axonal growth and migration of interneurons. Our data, taken together, suggest that TPC2 contributes to the severe phenotype in axon growth initiation, extension and interneuron migration in the absence of Rac1 and Rac3.
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Affiliation(s)
- Zouzana Kounoupa
- Institute of Molecular Biology and Biotechnology (IMBB, FORTH), Heraklion 71110, Greece.,Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion 71110, Greece
| | - Simona Tivodar
- Institute of Molecular Biology and Biotechnology (IMBB, FORTH), Heraklion 71110, Greece.,Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion 71110, Greece
| | - Kostas Theodorakis
- Institute of Molecular Biology and Biotechnology (IMBB, FORTH), Heraklion 71110, Greece.,Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion 71110, Greece
| | - Dimitrios Kyriakis
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, L-4365 Esch-sur-Alzette, Luxembourg
| | - Myrto Denaxa
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Centre 'Al. Fleming', Vari, 16672, Greece
| | - Domna Karagogeos
- Institute of Molecular Biology and Biotechnology (IMBB, FORTH), Heraklion 71110, Greece.,Department of Basic Science, Faculty of Medicine, University of Crete, Heraklion 71110, Greece
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3
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Kingston R, Amin D, Misra S, Gross JM, Kuwajima T. Serotonin transporter-mediated molecular axis regulates regional retinal ganglion cell vulnerability and axon regeneration after nerve injury. PLoS Genet 2021; 17:e1009885. [PMID: 34735454 PMCID: PMC8594818 DOI: 10.1371/journal.pgen.1009885] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 11/16/2021] [Accepted: 10/17/2021] [Indexed: 11/19/2022] Open
Abstract
Molecular insights into the selective vulnerability of retinal ganglion cells (RGCs) in optic neuropathies and after ocular trauma can lead to the development of novel therapeutic strategies aimed at preserving RGCs. However, little is known about what molecular contexts determine RGC susceptibility. In this study, we show the molecular mechanisms underlying the regional differential vulnerability of RGCs after optic nerve injury. We identified RGCs in the mouse peripheral ventrotemporal (VT) retina as the earliest population of RGCs susceptible to optic nerve injury. Mechanistically, the serotonin transporter (SERT) is upregulated on VT axons after injury. Utilizing SERT-deficient mice, loss of SERT attenuated VT RGC death and led to robust retinal axon regeneration. Integrin β3, a factor mediating SERT-induced functions in other systems, is also upregulated in RGCs and axons after injury, and loss of integrin β3 led to VT RGC protection and axon regeneration. Finally, RNA sequencing analyses revealed that loss of SERT significantly altered molecular signatures in the VT retina after optic nerve injury, including expression of the transmembrane protein, Gpnmb. GPNMB is rapidly downregulated in wild-type, but not SERT- or integrin β3-deficient VT RGCs after injury, and maintaining expression of GPNMB in RGCs via AAV2 viruses even after injury promoted VT RGC survival and axon regeneration. Taken together, our findings demonstrate that the SERT-integrin β3-GPNMB molecular axis mediates selective RGC vulnerability and axon regeneration after optic nerve injury.
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Affiliation(s)
- Rody Kingston
- Department of Ophthalmology, The Louis J. Fox Center for Vision Restoration, Pittsburgh, Pennsylvania, United States of America
| | - Dwarkesh Amin
- Department of Ophthalmology, The Louis J. Fox Center for Vision Restoration, Pittsburgh, Pennsylvania, United States of America
| | - Sneha Misra
- Department of Ophthalmology, The Louis J. Fox Center for Vision Restoration, Pittsburgh, Pennsylvania, United States of America
| | - Jeffrey M. Gross
- Department of Ophthalmology, The Louis J. Fox Center for Vision Restoration, Pittsburgh, Pennsylvania, United States of America
- Department of Developmental Biology, The McGowan Institute for Regenerative Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Takaaki Kuwajima
- Department of Ophthalmology, The Louis J. Fox Center for Vision Restoration, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Dumitru CA, Brouwer E, Stelzer T, Nocerino S, Rading S, Wilkens L, Sandalcioglu IE, Karsak M. Dynein Light Chain Protein Tctex1: A Novel Prognostic Marker and Molecular Mediator in Glioblastoma. Cancers (Basel) 2021; 13:cancers13112624. [PMID: 34071761 PMCID: PMC8199143 DOI: 10.3390/cancers13112624] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 11/25/2022] Open
Abstract
Simple Summary Glioblastoma (GBM) remains one of the deadliest solid cancers, with only a dismal proportion of GBM patients achieving 5-year survival. Thus, it is critical to identify molecular mechanisms that could be targeted by novel therapeutic approaches in this tumor type. Our study identified Tctex1/DYNLT1 as an independent prognostic marker for the overall survival of GBM patients. Importantly, Tctex1 promoted the aggressiveness of GBM cells by enhancing tumor proliferation and invasion. These effects of Tctex1 appeared to be modulated via phosphorylation of retinoblastoma protein (RB) and the release of matrix metalloprotease 2 (MMP2), respectively. As Tctex1 can potentially be inhibited in vivo, our study provides a rationale for novel, individualized therapeutic strategies in GBM patients. Abstract The purpose of this study was to determine the role of Tctex1 (DYNLT1, dynein light chain-1) in the pathophysiology of glioblastoma (GBM). To this end, we performed immunohistochemical analyses on tissues from GBM patients (n = 202). Tctex1 was additionally overexpressed in two different GBM cell lines, which were then evaluated in regard to their proliferative and invasive properties. We found that Tctex1 levels were significantly higher in GBM compared to healthy adjacent brain tissues. Furthermore, high Tctex1 expression was significantly associated with the short overall- (p = 0.002, log-rank) and progression-free (p = 0.028, log-rank) survival of GBM patients and was an independent predictor of poor overall survival in multivariate Cox-regression models. In vitro, Tctex1 promoted the metabolic activity, anchorage-independent growth and proliferation of GBM cells. This phenomenon was previously shown to occur via the phosphorylation of retinoblastoma protein (phospho-RB). Here, we found a direct and significant correlation between the levels of Tctex1 and phospho-RB (Ser807/801) in tissues from GBM patients (p = 0.007, Rho = 0.284, Spearman’s rank). Finally, Tctex1 enhanced the invasiveness of GBM cells and the release of pro-invasive matrix metalloprotease 2 (MMP2). These findings indicate that Tctex1 promotes GBM progression and therefore might be a useful therapeutic target in this type of cancer.
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Affiliation(s)
- Claudia Alexandra Dumitru
- Department of Neurosurgery, Otto-von-Guericke University, 39120 Magdeburg, Germany;
- Correspondence: (C.A.D.); (M.K.)
| | - Eileen Brouwer
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (E.B.); (T.S.); (S.N.); (S.R.)
| | - Tamina Stelzer
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (E.B.); (T.S.); (S.N.); (S.R.)
| | - Salvatore Nocerino
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (E.B.); (T.S.); (S.N.); (S.R.)
| | - Sebastian Rading
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (E.B.); (T.S.); (S.N.); (S.R.)
| | - Ludwig Wilkens
- Department of Pathology, Nordstadt Hospital Hannover, 30167 Hannover, Germany;
| | | | - Meliha Karsak
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; (E.B.); (T.S.); (S.N.); (S.R.)
- Correspondence: (C.A.D.); (M.K.)
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5
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Xu M, Shaw KL. Extensive Linkage and Genetic Coupling of Song and Preference Loci Underlying Rapid Speciation in Laupala Crickets. J Hered 2021; 112:204-213. [PMID: 33438016 DOI: 10.1093/jhered/esab001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 01/11/2021] [Indexed: 12/20/2022] Open
Abstract
In nature, closely related species commonly display divergent mating behaviors, suggesting a central role for such traits in the origin of species. Elucidating the genetic basis of divergence in these traits is necessary to understand the evolutionary process leading to reproductive barriers and speciation. The rapidly speciating Hawaiian crickets of the genus Laupala provides an ideal system for dissecting the genetic basis of mating behavior divergence. In Laupala, closely related species differ markedly in male song pulse rate and female preference for pulse rate. These behaviors play an important role in determining mating patterns. Previous studies identified a genetic architecture consisting of numerous small to moderate effect loci causing interspecific differences in pulse rate and preference, including colocalizing pulse rate and preference QTL on linkage group one (LG1). To further interrogate these QTL, we conduct a fine mapping study using high-density SNP linkage maps. With improved statistical power and map resolution, we provide robust evidence for genetic coupling between song and preference, along with two additional pulse rate QTL on LG1, revealing a more resolved picture of the genetic architecture underlying mating behavior divergence. Our sequence-based genetic map, along with dramatically narrowed QTL confidence intervals, allowed us to annotate genes within the QTL regions and identify several exciting candidate genes underlying variation in pulse rate and preference divergence. Such knowledge suggests potential molecular mechanisms underlying the evolution of behavioral barriers.
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Affiliation(s)
- Mingzi Xu
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY
| | - Kerry L Shaw
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY
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6
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Saito M, Otsu W. [Mechanisms of cell proliferation through primary cilium]. Nihon Yakurigaku Zasshi 2019; 154:197-202. [PMID: 31597899 DOI: 10.1254/fpj.154.197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Primary cilium is a membrane-protruding sensory organelle, which is organized from a basal body in G0/G1 phase cells. The resorption of primary cilia under specific growth factor stimuli is coupled to cell cycle re-entry and cell proliferation, and the proliferative function is vital for the organization of organs at an embryonic stage. In fact, abnormalities in ciliogenesis and/or cilium-derived signaling lead to malformation of various organs, such as the brain, eyes, nose, ear, heart, lung, liver, kidney, and bones. The inborn genetic disorders are collectively called 〝ciliopathy〟. However, the pathogenesis of the ciliopathies has largely remained unexplained, especially little is known about the cellular machinery that controls the ciliary resorption. Tctex-1 (t-complex testis expressed-1), one of the light chains of cytoplasmic dynein complex, regulates intracellular trafficking along microtubule. Tctex-1 phosphorylated at Thr94 is, in turn, free from the dynein complex to execute dynein-free functions. This review summarizes the current situation of the mechanisms of ciliary resorption with a central focus on the role of phosphorylated Tctex-1.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Pharmacology, Tohoku University School of Medicine
| | - Wataru Otsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University.,Department of Biomedical Research, Gifu Pharmaceutical University
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7
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Sierra-Fonseca JA, Bracamontes C, Saldecke J, Das S, Roychowdhury S. Activation of β- and α2-adrenergic receptors stimulate tubulin polymerization and promote the association of Gβγ with microtubules in cultured NIH3T3 cells. Biochem Biophys Res Commun 2018; 503:102-108. [PMID: 29852176 DOI: 10.1016/j.bbrc.2018.05.188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 05/28/2018] [Indexed: 12/15/2022]
Abstract
Microtubules (MTs) constitute a crucial part of the cytoskeleton and are essential for cell division and differentiation, cell motility, intracellular transport, and cell morphology. Precise regulation of MT assembly and dynamics is essential for the performance of these functions. Although much progress has been made in identifying and characterizing the cellular factors that regulate MT assembly and dynamics, signaling events in this process is not well understood. Gβγ, an important component of the G protein-coupled receptor (GPCR) signaling pathway, has been shown to promote MT assembly in vitro and in cultured NIH3T3 and PC12 cells. Using the MT depolymerizing agent nocodazole, it has been demonstrated that the association of Gβγ with polymerized tubulin is critical for MT assembly. More recently, Gβγ has been shown to play a key role in NGF-induced neuronal differentiation of PC12 cells through its interaction with tubulin/MTs and modulation of MT assembly. Although NGF is known to exert its effect through tyrosine kinase receptor TrkA, the result suggests a possible involvement of GPCRs in this process. The present study was undertaken to determine whether agonist activation of GPCR utilizes Gβγ to promote MT assembly. We used isoproterenol and UK 14,304, agonists for two different GPCRs (β- and α2-adrenergic receptors, respectively) known to activate Gs and Gi respectively, with an opposing effect on production of cAMP. The results demonstrate that the agonist activation of β- and α2-adrenergic receptors promotes the association of Gβγ with MTs and stimulates MT assembly in NIH3T3 cells. Interestingly, the effects of these two agonists were more prominent when the cellular level of MT assembly was low (30% or less). In contrast to MT assembly, actin polymerization was not affected by isoproterenol or UK 14, 304 indicating that the effects of these agonists are limited to MTs. Thus, it appears that, upon cellular demand, GPCRs may utilize Gβγ to promote MT assembly. Stimulation of MT assembly appears to be a novel function of G protein-mediated signaling.
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Affiliation(s)
| | - Christina Bracamontes
- Department of Biological Sciences, 500 West University Avenue, 79968, El Paso, TX, USA; Department of Obstetrics and Gynecology, Texas Tech University Health Sciences Center at El Paso, TX, USA
| | - Jessica Saldecke
- Department of Biological Sciences, 500 West University Avenue, 79968, El Paso, TX, USA
| | - Siddhartha Das
- Department of Biological Sciences, 500 West University Avenue, 79968, El Paso, TX, USA; Infectious Diseases/Immunology, TX, USA
| | - Sukla Roychowdhury
- Department of Biological Sciences, 500 West University Avenue, 79968, El Paso, TX, USA; Neuromodulation Disorders Clusters, Border Biomedical Research Center, University of Texas, 79968, El Paso, TX, USA.
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8
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Ismail OZ, Sriranganathan S, Zhang X, Bonventre JV, Zervos AS, Gunaratnam L. Tctex-1, a novel interaction partner of Kidney Injury Molecule-1, is required for efferocytosis. J Cell Physiol 2018; 233:6877-6895. [PMID: 29693725 DOI: 10.1002/jcp.26578] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 03/01/2018] [Indexed: 02/04/2023]
Abstract
Kidney injury molecule-1 (KIM-1) is a phosphatidylserine receptor that is specifically upregulated on proximal tubular epithelial cells (PTECs) during acute kidney injury and mitigates tissue damage by mediating efferocytosis (the phagocytic clearance of apoptotic cells). The signaling molecules that regulate efferocytosis in TECs are not well understood. Using a yeast two-hybrid screen, we identified the dynein light chain protein, Tctex-1, as a novel KIM-1-interacting protein. Immunoprecipitation and confocal imaging studies suggested that Tctex-1 associates with KIM-1 in cells at baseline, but, dissociates from KIM-1 within 90 min of initiation of efferocytosis. Interfering with actin or microtubule polymerization interestingly prevented the dissociation of KIM-1 from Tctex-1. Moreover, the subcellular localization of Tctex-1 changed from being microtubule-associated to mainly cytosolic upon expression of KIM-1. Short hairpin RNA-mediated silencing of endogenous Tctex-1 in cells significantly inhibited efferocytosis to levels comparable to that of knock down of KIM-1 in the same cells. Importantly, Tctex-1 was not involved in the delivery of KIM-1 to the cell-surface. On the other hand, KIM-1 expression significantly inhibited the phosphorylation of Tctex-1 at threonine 94 (T94), a post-translational modification which is known to disrupt the binding of Tctex-1 to dynein on microtubules. In keeping with this, we found that KIM-1 bound less efficiently to the phosphomimic (T94E) mutant of Tctex-1 compared to wild type Tctex-1. Surprisingly, expression of Tctex-1 T94E did not influence KIM-1-mediated efferocytosis. Our studies uncover a previously unknown role for Tctex-1 in KIM-1-dependent efferocytosis in epithelial cells.
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Affiliation(s)
- Ola Z Ismail
- Matthew Mailing Center for Translational Transplant Studies, London Health Sciences Center, Lawson Health Research Institute, London, Ontario, Canada
| | - Saranga Sriranganathan
- Matthew Mailing Center for Translational Transplant Studies, London Health Sciences Center, Lawson Health Research Institute, London, Ontario, Canada
| | - Xizhong Zhang
- Matthew Mailing Center for Translational Transplant Studies, London Health Sciences Center, Lawson Health Research Institute, London, Ontario, Canada
| | - Joseph V Bonventre
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Antonis S Zervos
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, Florida
| | - Lakshman Gunaratnam
- Matthew Mailing Center for Translational Transplant Studies, London Health Sciences Center, Lawson Health Research Institute, London, Ontario, Canada.,Division of Nephrology, Department of Medicine, Schulich School of Medicine and Dentistry, London, Western University, Ontario, Canada
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9
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Guo Y, He X, Zhao L, Liu L, Song H, Wang X, Xu J, Ju X, Guo W, Zhu X. Gβ2 Regulates the Multipolar-Bipolar Transition of Newborn Neurons in the Developing Neocortex. Cereb Cortex 2018; 27:3414-3426. [PMID: 28334111 DOI: 10.1093/cercor/bhx042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Indexed: 01/14/2023] Open
Abstract
Proper neuronal migration is critical for the formation of the six-layered neocortex in the mammalian brain. However, the precise control of neuronal migration is not well understood. Heterotrimeric guanine nucleotide binding proteins (G proteins), composed of Gα and Gβγ, transduce signals from G protein-coupled receptors to downstream effectors and play crucial roles in brain development. However, the functions of individual subunits of G proteins in prenatal brain development remain unclear. Here, we report that Gβ2 is expressed in the embryonic neocortex, with abundant expression in the intermediate zone, and is significantly upregulated in differentiated neurons. Perturbation of Gβ2 expression impairs the morphogenetic transformation of migrating neurons from multipolar to bipolar and subsequently delays neuronal migration. Moreover, Gβ2 acts as a scaffold protein to organize the MP1-MEK1-ERK1/2 complex and mediates the phosphorylation of ERK1/2. Importantly, expression of a constitutively active variant of MEK1 rescues the migration defects that are caused by the loss of Gβ2. In conclusion, our findings reveal that Gβ2 regulates proper neuronal migration during neocortex development by activating the ERK1/2 signaling pathway.
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Affiliation(s)
- Ye Guo
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Xiaoxiao He
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Lu Zhao
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Lin Liu
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Huifang Song
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Xudong Wang
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Jiahui Xu
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Xingda Ju
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
| | - Weixiang Guo
- State Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaojuan Zhu
- Key Laboratory of Molecular Epigenetics, Ministry of Education and Institute of Cytology and Genetics, Northeast Normal University, Changchun 130024, China
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10
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Li G, Huang J, Yang J, He D, Wang C, Qi X, Taylor IA, Liu J, Peng YL. Structure based function-annotation of hypothetical protein MGG_01005 from Magnaporthe oryzae reveals it is the dynein light chain orthologue of dynlt1/3. Sci Rep 2018; 8:3952. [PMID: 29500373 PMCID: PMC5834530 DOI: 10.1038/s41598-018-21667-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 02/07/2018] [Indexed: 11/09/2022] Open
Abstract
Magnaporthe oryzae is a model fungal plant pathogen employed for studying plant-fungi interactions. Whole genome sequencing and bioinformatics analyses revealed that this fungal pathogen has more than 12,000 protein-coding genes with 65% of the genes remaining functionally un-annotated. Here, we determine the structure of the hypothetical protein, MGG_01005 and show that it is the Magnaporthe oryzae Dynein light chain Tctex-type 1 (dynlt1/3), demonstrated by its structural similarity to other orthologous dynlt1 proteins and its conserved interaction with the N-terminus of the Magnaporthe oryzae dynein intermediate chain, MoDyn1I2. In addition, we present the structure of the MGG_01005-MoDyn1I2 complex together with mutagenesis studies that reveals a di-histidine motif interaction with a glutamate residue in the dynein intermediate chain within a conserved molecular interface. These results demonstrate the utility of structure-based annotation and validate it as a viable approach for the molecular assignment of hypothetic proteins from phyto-pathogenic fungi.
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Affiliation(s)
- Guorui Li
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.,College of life science, Inner Mongolia University for Nationalities, No. 996 Xilamulun Street, Tongliao, 028043, China
| | - Jinguang Huang
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.,State key Laboratory of Agrobiotechnology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.,College of Agronomy and Plant Protection, Qingdao Agricultural University, Qingdao, Shandong, 266109, China
| | - Jun Yang
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.,State key Laboratory of Agrobiotechnology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China
| | - Dan He
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.,State key Laboratory of Agrobiotechnology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China
| | - Chao Wang
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China
| | - Xiaoxuan Qi
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.
| | - Junfeng Liu
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.
| | - You-Liang Peng
- MOA Key Laboratory of Plant Pathology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China. .,State key Laboratory of Agrobiotechnology, China Agricultural University, No2 Yunamingyuanxilu, Beijing, 100193, China.
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11
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Wang Y, Terrell AM, Riggio BA, Anand D, Lachke SA, Duncan MK. β1-Integrin Deletion From the Lens Activates Cellular Stress Responses Leading to Apoptosis and Fibrosis. Invest Ophthalmol Vis Sci 2017; 58:3896-3922. [PMID: 28763805 PMCID: PMC5539801 DOI: 10.1167/iovs.17-21721] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Purpose Previous research showed that the absence of β1-integrin from the mouse lens after embryonic day (E) 13.5 (β1MLR10) leads to the perinatal apoptosis of lens epithelial cells (LECs) resulting in severe microphthalmia. This study focuses on elucidating the molecular connections between β1-integrin deletion and this phenotype. Methods RNA sequencing was performed to identify differentially regulated genes (DRGs) in β1MLR10 lenses at E15.5. By using bioinformatics analysis and literature searching, Egr1 (early growth response 1) was selected for further study. The activation status of certain signaling pathways (focal adhesion kinase [FAK]/Erk, TGF-β, and Akt signaling) was studied via Western blot and immunohistochemistry. Mice lacking both β1-integrin and Egr1 genes from the lenses were created (β1MLR10/Egr1−/−) to study their relationship. Results RNA sequencing identified 120 DRGs that include candidates involved in the cellular stress response, fibrosis, and/or apoptosis. Egr1 was investigated in detail, as it mediates cellular stress responses in various cell types, and is recognized as an upstream regulator of numerous other β1MLR10 lens DRGs. In β1MLR10 mice, Egr1 levels are elevated shortly after β1-integrin loss from the lens. Further, pErk1/2 and pAkt are elevated in β1MLR10 LECs, thus providing the potential signaling mechanism that causes Egr1 upregulation in the mutant. Indeed, deletion of Egr1 from β1MLR10 lenses partially rescues the microphthalmia phenotype. Conclusions β1-integrin regulates the appropriate levels of Erk1/2 and Akt phosphorylation in LECs, whereas its deficiency results in the overexpression of Egr1, culminating in reduced cell survival. These findings provide insight into the molecular mechanism underlying the microphthalmia observed in β1MLR10 mice.
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Affiliation(s)
- Yichen Wang
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States
| | - Anne M Terrell
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States
| | - Brittany A Riggio
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States
| | - Deepti Anand
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States
| | - Melinda K Duncan
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States
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12
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Saito M, Otsu W, Hsu KS, Chuang JZ, Yanagisawa T, Shieh V, Kaitsuka T, Wei FY, Tomizawa K, Sung CH. Tctex-1 controls ciliary resorption by regulating branched actin polymerization and endocytosis. EMBO Rep 2017; 18:1460-1472. [PMID: 28607034 DOI: 10.15252/embr.201744204] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/13/2017] [Accepted: 05/16/2017] [Indexed: 11/09/2022] Open
Abstract
The primary cilium is a plasma membrane-protruding sensory organelle that undergoes regulated assembly and resorption. While the assembly process has been studied extensively, the cellular machinery that governs ciliary resorption is less well understood. Previous studies showed that the ciliary pocket membrane is an actin-rich, endocytosis-active periciliary subdomain. Furthermore, Tctex-1, originally identified as a cytoplasmic dynein light chain, has a dynein-independent role in ciliary resorption upon phosphorylation at Thr94. Here, we show that the remodeling and endocytosis of the ciliary pocket membrane are accelerated during ciliary resorption. This process depends on phospho(T94)Tctex-1, actin, and dynamin. Mechanistically, Tctex-1 physically and functionally interacts with the actin dynamics regulators annexin A2, Arp2/3 complex, and Cdc42. Phospho(T94)Tctex-1 is required for Cdc42 activation before the onset of ciliary resorption. Moreover, inhibiting clathrin-dependent endocytosis or suppressing Rab5GTPase on early endosomes effectively abrogates ciliary resorption. Taken together with the epistasis functional assays, our results support a model in which phospho(T94)Tctex-1-regulated actin polymerization and periciliary endocytosis play an active role in orchestrating the initial phase of ciliary resorption.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Pharmacology, Graduate School of Medicine, Tohoku University, Aoba-ku Sendai, Japan .,Department of Cellular Signaling, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku Sendai, Japan.,Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Wataru Otsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Kuo-Shun Hsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Jen-Zen Chuang
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Teruyuki Yanagisawa
- Department of Molecular Pharmacology, Graduate School of Medicine, Tohoku University, Aoba-ku Sendai, Japan
| | - Vincent Shieh
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA
| | - Taku Kaitsuka
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Ching-Hwa Sung
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY, USA .,Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, NY, USA
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13
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Neuert H, Yuva-Aydemir Y, Silies M, Klämbt C. Different modes of APC/C activation control growth and neuron-glia interaction in the developing Drosophila eye. Development 2017; 144:4673-4683. [DOI: 10.1242/dev.152694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 10/23/2017] [Indexed: 12/30/2022]
Abstract
The development of the nervous system requires tight control of cell division, fate specification and migration. The anaphase promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase that affects different steps of cell cycle progression, as well as having postmitotic functions in nervous system development. It can therefore link different developmental stages in one tissue. The two adaptor proteins Fizzy/Cdc20 and Fizzy-Related/Cdh1 confer APC/C substrate specificity. Here we show that two distinct modes of APC/C function act during Drosophila eye development. Fizzy/Cdc20 controls the early growth of the eye disc anlage and the concomitant entry of glial cells onto the disc. In contrast, fzr/cdh1 acts during neuronal patterning and photoreceptor axon growth, and subsequently affects neuron-glia interaction. To further address the postmitotic role of Fzr/Cdh1 in controlling neuron-glia interaction, we identified a series of novel APC/C candidate substrates. Four of our candidate genes are required for fzr/cdh1 dependent neuron-glia interaction, including the dynein light chain Dlc90F. Taken together, our data show how different modes of APC/C activation can couple early growth and neuron-glia interaction during eye disc development.
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Affiliation(s)
- Helen Neuert
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
- Present address: Department of Cellular and Physiological Sciences, Life Sciences Centre, 2350 Health Sciences Mall, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Yeliz Yuva-Aydemir
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
- Present address: Department of Neurology, UMASS Medical School, Worcester, MA 01605, USA
| | - Marion Silies
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
- European Neuroscience Institute, University Medical Center Goettingen, Grisebachstr. 5, 37077 Göttingen, Germany
| | - Christian Klämbt
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
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14
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Ochiai K, Morimatsu M, Kato Y, Ishiguro-Oonuma T, Udagawa C, Rungsuriyawiboon O, Azakami D, Michishita M, Ariyoshi Y, Ueki H, Nasu Y, Kumon H, Watanabe M, Omi T. Tumor suppressor REIC/DKK-3 and co-chaperone SGTA: Their interaction and roles in the androgen sensitivity. Oncotarget 2016; 7:3283-96. [PMID: 26658102 PMCID: PMC4823106 DOI: 10.18632/oncotarget.6488] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/21/2015] [Indexed: 12/16/2022] Open
Abstract
REIC/DKK-3 is a tumor suppressor, however, its intracellular physiological functions and interacting molecules have not been fully clarified. Using yeast two-hybrid screening, we found that small glutamine-rich tetratricopeptide repeat-containing protein α (SGTA), known as a negative modulator of cytoplasmic androgen receptor (AR) signaling, is a novel interacting partner of REIC/DKK-3. Mammalian two-hybrid and pull-down assay results indicated that the SGTA-REIC/DKK-3 interaction involved the N-terminal regions of both REIC/DKK-3 and SGTA and that REIC/DKK-3 interfered with the dimerization of SGTA, which is a component of the AR complex and a suppressor of dynein motor-dependent AR transport and signaling. A reporter assay in human prostate cancer cells that displayed suppressed AR signaling by SGTA showed recovery of AR signaling by REIC/DKK-3 expression. Considering these results and our previous data that REIC/DKK-3 interacts with the dynein light chain TCTEX-1, we propose that the REIC/DKK-3 protein interferes with SGTA dimerization, promotes dynein-dependent AR transport and then upregulates AR signaling.
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Affiliation(s)
- Kazuhiko Ochiai
- Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Masami Morimatsu
- Laboratory of Laboratory Animal Science and Medicine, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
| | - Yuiko Kato
- Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Toshina Ishiguro-Oonuma
- Department of Biological Resources, Integrated Center for Science, Ehime University, Ehime 791-0295, Japan
| | - Chihiro Udagawa
- Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Oumaporn Rungsuriyawiboon
- Department of Veterinary Technology Faculty of Veterinary Technology, Kasetsart University, Bangkok 10900, Thailand
| | - Daigo Azakami
- Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Masaki Michishita
- Department of Veterinary Pathology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Yuichi Ariyoshi
- Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Hideo Ueki
- Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Yasutomo Nasu
- Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Hiromi Kumon
- Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Masami Watanabe
- Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8558, Japan
| | - Toshinori Omi
- Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
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15
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Merino-Gracia J, Zamora-Carreras H, Bruix M, Rodríguez-Crespo I. Molecular Basis for the Protein Recognition Specificity of the Dynein Light Chain DYNLT1/Tctex1: CHARACTERIZATION OF THE INTERACTION WITH ACTIVIN RECEPTOR IIB. J Biol Chem 2016; 291:20962-20975. [PMID: 27502274 DOI: 10.1074/jbc.m116.736884] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Indexed: 01/19/2023] Open
Abstract
It has been suggested that DYNLT1, a dynein light chain known to bind to various cellular and viral proteins, can function both as a molecular clamp and as a microtubule-cargo adapter. Recent data have shown that the DYNLT1 homodimer binds to two dynein intermediate chains to subsequently link cargo proteins such as the guanine nucleotide exchange factor Lfc or the small GTPases RagA and Rab3D. Although over 20 DYNLT1-interacting proteins have been reported, the exact sequence requirements that enable their association to the canonical binding groove or to the secondary site within the DYNLT1 surface are unknown. We describe herein the sequence recognition properties of the hydrophobic groove of DYNLT1 known to accommodate dynein intermediate chain. Using a pepscan approach, we have substituted each amino acid within the interacting peptide for all 20 natural amino acids and identified novel binding sequences. Our data led us to propose activin receptor IIB as a novel DYNLT1 ligand and suggest that DYNLT1 functions as a molecular dimerization engine bringing together two receptor monomers in the cytoplasmic side of the membrane. In addition, we provide evidence regarding a dual binding mode adopted by certain interacting partners such as Lfc or the parathyroid hormone receptor. Finally, we have used NMR spectroscopy to obtain the solution structure of human DYNLT1 forming a complex with dynein intermediate chain of ∼74 kDa; it is the first mammalian structure available.
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Affiliation(s)
- Javier Merino-Gracia
- From the Departamento Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain and
| | - Héctor Zamora-Carreras
- Departamento Química Física Biológica, Instituto Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Serrano 119, 28006 Madrid, Spain
| | - Marta Bruix
- Departamento Química Física Biológica, Instituto Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Serrano 119, 28006 Madrid, Spain
| | - Ignacio Rodríguez-Crespo
- From the Departamento Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain and
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16
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Mestres I, Chuang JZ, Calegari F, Conde C, Sung CH. SARA regulates neuronal migration during neocortical development through L1 trafficking. Development 2016; 143:3143-53. [PMID: 27471254 DOI: 10.1242/dev.129338] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 07/17/2016] [Indexed: 12/21/2022]
Abstract
Emerging evidence suggests that endocytic trafficking of adhesion proteins plays a crucial role in neuronal migration during neocortical development. However, molecular insights into these processes remain elusive. Here, we study the early endosomal protein Smad anchor for receptor activation (SARA) in the developing mouse brain. SARA is enriched at the apical endfeet of radial glia of the neocortex. Although SARA knockdown did not lead to detectable neurogenic phenotypes, SARA-suppressed neurons exhibited impaired orientation and migration across the intermediate zone. Mechanistically, we show that SARA knockdown neurons exhibit increased surface expression of the L1 cell adhesion molecule. Neurons ectopically expressing L1 phenocopy the migration and orientation defects caused by SARA knockdown and display increased contact with neighboring neurites. L1 knockdown effectively rescues SARA suppression-induced phenotypes. SARA knockdown neurons eventually overcome their migration defect and enter later into the cortical plate. Nevertheless, these neurons localize at more superficial cortical layers than their control counterparts. These results suggest that SARA regulates the orientation, multipolar-to-bipolar transition and the positioning of cortical neurons via modulating surface L1 expression.
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Affiliation(s)
- Iván Mestres
- INIMEC, Instituto de Investigación Médica Mercedes y Martín Ferreyra, CONICET, Universidad Nacional de Córdoba UNC, Friuli 2434-5016, Córdoba, Argentina DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Fetscherstrasse 105, Dresden 01307, Germany
| | - Jen-Zen Chuang
- Department of Ophthalmology, Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Federico Calegari
- DFG-Research Center for Regenerative Therapies, Cluster of Excellence, TU-Dresden, Fetscherstrasse 105, Dresden 01307, Germany
| | - Cecilia Conde
- INIMEC, Instituto de Investigación Médica Mercedes y Martín Ferreyra, CONICET, Universidad Nacional de Córdoba UNC, Friuli 2434-5016, Córdoba, Argentina Instituto Universitario Ciencias Biomédicas Córdoba (IUCBC), Córdoba 5016, Argentina
| | - Ching-Hwa Sung
- Department of Ophthalmology, Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA Departments of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, NY 10065, USA
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17
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Impairments in dendrite morphogenesis as etiology for neurodevelopmental disorders and implications for therapeutic treatments. Neurosci Biobehav Rev 2016; 68:946-978. [PMID: 27143622 DOI: 10.1016/j.neubiorev.2016.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 02/08/2023]
Abstract
Dendrite morphology is pivotal for neural circuitry functioning. While the causative relationship between small-scale dendrite morphological abnormalities (shape, density of dendritic spines) and neurodevelopmental disorders is well established, such relationship remains elusive for larger-scale dendrite morphological impairments (size, shape, branching pattern of dendritic trees). Here, we summarize published data on dendrite morphological irregularities in human patients and animal models for neurodevelopmental disorders, with focus on autism and schizophrenia. We next discuss high-risk genes for these disorders and their role in dendrite morphogenesis. We finally overview recent developments in therapeutic attempts and we discuss how they relate to dendrite morphology. We find that both autism and schizophrenia are accompanied by dendritic arbor morphological irregularities, and that majority of their high-risk genes regulate dendrite morphogenesis. Thus, we present a compelling argument that, along with smaller-scale morphological impairments in dendrites (spines and synapse), irregularities in larger-scale dendrite morphology (arbor shape, size) may be an important part of neurodevelopmental disorders' etiology. We suggest that this should not be ignored when developing future therapeutic treatments.
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18
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Indu S, Sekhar SC, Sengottaiyan J, Kumar A, Pillai SM, Laloraya M, Kumar PG. Aberrant Expression of Dynein light chain 1 (DYNLT1) is Associated with Human Male Factor Infertility. Mol Cell Proteomics 2015; 14:3185-95. [PMID: 26432663 DOI: 10.1074/mcp.m115.050005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Indexed: 12/18/2022] Open
Abstract
DYNLT1 is a member of a gene family identified within the t-complex of the mouse, which has been linked with male germ cell development and function in the mouse and the fly. Though defects in the expression of this gene are associated with male sterility in both these models, there has been no study examining its association with spermatogenic defects in human males. In this study, we evaluated the levels of DYNLT1 and its expression product in the germ cells of fertile human males and males suffering from spermatogenic defects. We screened fertile (n = 14), asthenozoospermic (n = 15), oligozoospermic (n = 20) and teratozoospermic (n = 23) males using PCR and Western blot analysis. Semiquantitative PCR indicated either undetectable or significantly lower levels of expression of DYNLT1 in the germ cells from several patients from across the three infertility syndrome groups, when compared with that of fertile controls. DYNLT1 was localized on head, mid-piece, and tail segments of spermatozoa from fertile males. Spermatozoa from infertile males presented either a total absence of DYNLT1 or its absence in the tail region. Majority of the infertile individuals showed negligible levels of localization of DYNLT1 on the spermatozoa. Overexpression of DYNLT1 in GC1-spg cell line resulted in the up-regulation of several cytoskeletal proteins and molecular chaperones involved in cell cycle regulation. Defective expression of DYNLT1 was associated with male factor infertility syndromes in our study population. Proteome level changes in GC1-spg cells overexpressing DYNLT1 were suggestive of its possible function in germ cell development. We have discussed the implications of these observations in the light of the known functions of DYNLT1, which included protein trafficking, membrane vesiculation, cell cycle regulation, and stem cell differentiation.
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Affiliation(s)
- Sivankutty Indu
- From the ‡Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India
| | - Sreeja C Sekhar
- From the ‡Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India
| | - Jeeva Sengottaiyan
- From the ‡Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India
| | - Anil Kumar
- From the ‡Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India
| | - Sathy M Pillai
- §Dr. SathyPillai, Samad Hospital, V.V.Road, Pattoor, Thiruvananthapuram-695035. Kerala, India
| | - Malini Laloraya
- From the ‡Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India
| | - Pradeep G Kumar
- From the ‡Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India;
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19
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Nagler M, Palkowitsch L, Rading S, Moepps B, Karsak M. Cannabinoid receptor 2 expression modulates Gβ(1)γ(2) protein interaction with the activator of G protein signalling 2/dynein light chain protein Tctex-1. Biochem Pharmacol 2015; 99:60-72. [PMID: 26410677 DOI: 10.1016/j.bcp.2015.09.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/22/2015] [Indexed: 11/19/2022]
Abstract
The activator of G protein signalling AGS2 (Tctex-1) forms protein complexes with Gβγ, and controls cell proliferation by regulating cell cycle progression. A direct interaction of Tctex-1 with various G protein-coupled receptors has been reported. Since the carboxyl terminal portion of CB2 carries a putative Tctex-1 binding motif, we investigated the potential interplay of CB2 and Tctex-1 in the absence and presence of Gβγ. The supposed interaction of cannabinoid receptor CB2 with Tctex-1 and the influence of CB2 on the formation of Tctex-1-Gβγ-complexes were studied by co- and/or immunoprecipitation experiments in transiently transfected HEK293 cells. The analysis on Tctex-1 protein was performed in the absence and presence of the ligands JWH 133, 2-AG, and AM 630, the protein biosynthesis inhibitor cycloheximide or the protein degradation blockers MG132, NH4Cl/leupeptin or bafilomycin. Our results show that CB2 neither directly nor indirectly via Gβγ interacts with Tctex-1, but competes with Tctex-1 in binding to Gβγ. The Tctex-1-Gβγ protein interaction was disrupted by CB2 receptor expression resulting in a release of Tctex-1 from the complex, and its degradation by the proteasome and partly by lysosomes. The decrease in Tctex-1 protein levels is induced by CB2 expression "dose-dependently" and is independent of stimulation by agonist or blocking by an inverse agonist treatment. The results suggest that CB2 receptor expression independent of its activation by agonists is sufficient to competitively disrupt Gβγ-Tctex-1 complexes, and to initiate Tctex-1 degradation. These findings implicate that CB2 receptor expression modifies the stability of intracellular protein complexes by a non-canonical pathway.
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Affiliation(s)
- Marina Nagler
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; Institute of Pharmacology and Toxicology, Ulm University, 89081 Ulm, Germany
| | - Lysann Palkowitsch
- Institute of Physiological Chemistry, Ulm University, 89081 Ulm, Germany
| | - Sebastian Rading
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; Institute of Pharmacology and Toxicology, Ulm University, 89081 Ulm, Germany
| | - Barbara Moepps
- Institute of Pharmacology and Toxicology, Ulm University, 89081 Ulm, Germany
| | - Meliha Karsak
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany; Institute of Pharmacology and Toxicology, Ulm University, 89081 Ulm, Germany.
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20
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Copf T. Importance of gene dosage in controlling dendritic arbor formation during development. Eur J Neurosci 2015; 42:2234-49. [PMID: 26108333 DOI: 10.1111/ejn.13002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/05/2015] [Accepted: 06/18/2015] [Indexed: 12/11/2022]
Abstract
Proper dendrite morphology is crucial for normal nervous system functioning. While a number of genes have been implicated in dendrite morphogenesis in both invertebrates and mammals, it remains unclear how developing dendrites respond to changes in gene dosage and what type of patterns their responses may follow. To understand this, I review here evidence from the recent literature, focusing on the genetic studies performed in the Drosophila larval dendritic arborization class IV neuron, an excellent cell type to understand dendrite morphogenesis. I summarize how class IV arbors change morphology in response to developmental fluctuations in the expression levels of 47 genes, studied by means of genetic manipulations such as loss-of-function and gain-of-function, and for which sufficient information is available. I find that arbors can respond to changing gene dosage in several distinct ways, each characterized by a singular dose-response curve. Interestingly, in 72% of cases arbors are sensitive, and thus adjust their morphology, in response to both decreases and increases in the expression of a given gene, indicating that dendrite morphogenesis is a process particularly sensitive to gene dosage. By summarizing the parallels between Drosophila and mammals, I show that many Drosophila dendrite morphogenesis genes have orthologs in mammals, and that some of these are associated with mammalian dendrite outgrowth and human neurodevelopmental disorders. One notable disease-related molecule is kinase Dyrk1A, thought to be a causative factor in Down syndrome. Both increases and decreases in Dyrk1A gene dosage lead to impaired dendrite morphogenesis, which may contribute to Down syndrome pathoetiology.
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Affiliation(s)
- Tijana Copf
- Institute of Molecular Biology and Biotechnology, Nikolaou Plastira 100, PO Box 1385, Heraklion, GR-70013, Crete, Greece
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21
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Merino-Gracia J, García-Mayoral MF, Rapali P, Valero RA, Bruix M, Rodríguez-Crespo I. DYNLT (Tctex-1) forms a tripartite complex with dynein intermediate chain and RagA, hence linking this small GTPase to the dynein motor. FEBS J 2015; 282:3945-58. [PMID: 26227614 DOI: 10.1111/febs.13388] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/02/2015] [Accepted: 07/28/2015] [Indexed: 12/15/2022]
Abstract
It has been suggested that DYNLT, a dynein light chain known to bind to various cellular and viral proteins, can function as a microtubule-cargo adaptor. Recent data showed that DYNLT links the small GTPase Rab3D to microtubules and, for this to occur, the DYNLT homodimer needs to display a binding site for dynein intermediate chain together with a binding site for the small GTPase. We have analysed in detail how RagA, another small GTPase, associates to DYNLT. After narrowing down the binding site of RagA to DYNLT we could identify that a β strand, part of the RagA G3 box involved in nucleotide binding, mediates this association. Interestingly, we show that both microtubule-associated DYNLT and cytoplasmic DYNLT are equally able to bind to the small GTPases Rab3D and RagA. Using NMR spectroscopy, we analysed the binding of dynein intermediate chain and RagA to mammalian DYNLT. Our experiments identify residues of DYNLT affected by dynein intermediate chain binding and residues affected by RagA binding, hence distinguishing the docking site for each of them. In summary, our results shed light on the mechanisms adopted by DYNLT when binding to protein cargoes that become transported alongside microtubules bound to the dynein motor.
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Affiliation(s)
- Javier Merino-Gracia
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Spain
| | - María Flor García-Mayoral
- Departamento de Química Biológica, Instituto de Química-Física Rocasolano, CSIC, Serrano, Madrid, Spain
| | - Peter Rapali
- Dynamics of Cell Growth and Division, Institut de Biologie Cellulaire et de Génétique, Centre National de la Recherche Scientifique, Bordeaux, France
| | - Ruth Ana Valero
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Spain
| | - Marta Bruix
- Departamento de Química Biológica, Instituto de Química-Física Rocasolano, CSIC, Serrano, Madrid, Spain
| | - Ignacio Rodríguez-Crespo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Spain
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Mital J, Lutter EI, Barger AC, Dooley CA, Hackstadt T. Chlamydia trachomatis inclusion membrane protein CT850 interacts with the dynein light chain DYNLT1 (Tctex1). Biochem Biophys Res Commun 2015; 462:165-70. [PMID: 25944661 DOI: 10.1016/j.bbrc.2015.04.116] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 04/24/2015] [Indexed: 11/24/2022]
Abstract
Chlamydia trachomatis actively subverts the minus-end directed microtubule motor, dynein, to traffic along microtubule tracks to the Microtubule Organizing Center (MTOC) where it remains within a membrane bound replicative vacuole for the duration of its intracellular development. Unlike most substrates of the dynein motor, disruption of the dynactin cargo-linking complex by over-expression of the p50 dynamitin subunit does not inhibit C. trachomatis transport. A requirement for chlamydial protein synthesis to initiate this process suggests that a chlamydial product supersedes a requirement for p50 dynamitin. A yeast 2-hybrid system was used to screen the chlamydia inclusion membrane protein CT850 against a HeLa cell cDNA library and identified an interaction with the dynein light chain DYNLT1 (Tctex1). This interaction was at least partially dependent upon an (R/K-R/K-X-X-R/K) motif that is characteristic of DYNLT1 binding domains. CT850 expressed ectopically in HeLa cells localized at the MTOC and this localization is similarly dependent upon the predicted DYNLT1 binding domain. Furthermore, DYNLT1 is enriched at focal concentrations of CT850 on the chlamydial inclusion membrane that are known to interact with dynein and microtubules. Depletion of DYNLT1 disrupts the characteristic association of the inclusion membrane with centrosomes. Collectively, the results suggest that CT850 interacts with DYNLT1 to promote appropriate positioning of the inclusion at the MTOC.
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Affiliation(s)
- Jeffrey Mital
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA; Quinnipiac University, Hamden, CT 06518, USA
| | - Erika I Lutter
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Alexandra C Barger
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Cheryl A Dooley
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Ted Hackstadt
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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Sierra-Fonseca JA, Najera O, Martinez-Jurado J, Walker EM, Varela-Ramirez A, Khan AM, Miranda M, Lamango NS, Roychowdhury S. Nerve growth factor induces neurite outgrowth of PC12 cells by promoting Gβγ-microtubule interaction. BMC Neurosci 2014; 15:132. [PMID: 25552352 PMCID: PMC4302597 DOI: 10.1186/s12868-014-0132-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 11/27/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Assembly and disassembly of microtubules (MTs) is critical for neurite outgrowth and differentiation. Evidence suggests that nerve growth factor (NGF) induces neurite outgrowth from PC12 cells by activating the receptor tyrosine kinase, TrkA. G protein-coupled receptors (GPCRs) as well as heterotrimeric G proteins are also involved in regulating neurite outgrowth. However, the possible connection between these pathways and how they might ultimately converge to regulate the assembly and organization of MTs during neurite outgrowth is not well understood. RESULTS Here, we report that Gβγ, an important component of the GPCR pathway, is critical for NGF-induced neuronal differentiation of PC12 cells. We have found that NGF promoted the interaction of Gβγ with MTs and stimulated MT assembly. While Gβγ-sequestering peptide GRK2i inhibited neurite formation, disrupted MTs, and induced neurite damage, the Gβγ activator mSIRK stimulated neurite outgrowth, which indicates the involvement of Gβγ in this process. Because we have shown earlier that prenylation and subsequent methylation/demethylation of γ subunits are required for the Gβγ-MTs interaction in vitro, small-molecule inhibitors (L-28 and L-23) targeting prenylated methylated protein methyl esterase (PMPMEase) were tested in the current study. We found that these inhibitors disrupted Gβγ and ΜΤ organization and affected cellular morphology and neurite outgrowth. In further support of a role of Gβγ-MT interaction in neuronal differentiation, it was observed that overexpression of Gβγ in PC12 cells induced neurite outgrowth in the absence of added NGF. Moreover, overexpressed Gβγ exhibited a pattern of association with MTs similar to that observed in NGF-differentiated cells. CONCLUSIONS Altogether, our results demonstrate that βγ subunit of heterotrimeric G proteins play a critical role in neurite outgrowth and differentiation by interacting with MTs and modulating MT rearrangement.
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Affiliation(s)
- Jorge A Sierra-Fonseca
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
- />Present Address: Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Omar Najera
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
| | - Jessica Martinez-Jurado
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
| | - Ellen M Walker
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
| | - Armando Varela-Ramirez
- />Cytometry Screening and Imaging Core facility, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
| | - Arshad M Khan
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
| | - Manuel Miranda
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
| | - Nazarius S Lamango
- />College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307 USA
| | - Sukla Roychowdhury
- />Neuromodulation Disorders Cluster, Border Biomedical Research Center, University of Texas, El Paso, TX 79968 USA
- />Department of Biological Sciences, University of Texas, El Paso, TX 79968 USA
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24
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Sánchez-Martín FJ, Lindquist DM, Landero-Figueroa J, Zhang X, Chen J, Cecil KM, Medvedovic M, Puga A. Sex- and tissue-specific methylome changes in brains of mice perinatally exposed to lead. Neurotoxicology 2014; 46:92-100. [PMID: 25530354 DOI: 10.1016/j.neuro.2014.12.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 12/09/2014] [Accepted: 12/10/2014] [Indexed: 11/29/2022]
Abstract
Changes in DNA methylation and subsequent changes in gene expression regulation are the hallmarks of age- and tissue-dependent epigenetic drift and plasticity resulting from the combinatorial integration of genetic determinants and environmental cues. To determine whether perinatal lead exposure caused persistent DNA methylation changes in target tissues, we exposed mouse dams to 0, 3 or 30 ppm of lead acetate in drinking water for a period extending from 2 months prior to mating, through gestation, until weaning of pups at postnatal day-21, and analyzed whole-genome DNA methylation in brain cortex and hippocampus of 2-month old exposed and unexposed progeny. Lead exposure resulted in hypermethylation of three differentially methylated regions in the hippocampus of females, but not males. These regions mapped to Rn4.5s, Sfi1, and Rn45s loci in mouse chromosomes 2, 11 and 17, respectively. At a conservative fdr<0.001, 1623 additional CpG sites were differentially methylated in female hippocampus, corresponding to 117 unique genes. Sixty of these genes were tested for mRNA expression and showed a trend toward negative correlation between mRNA expression and methylation in exposed females but not males. No statistically significant methylome changes were detected in male hippocampus or in cortex of either sex. We conclude that exposure to lead during embryonic life, a time when the organism is most sensitive to environmental cues, appears to have a sex- and tissue-specific effect on DNA methylation that may produce pathological or physiological deviations from the epigenetic plasticity operative in unexposed mice.
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Affiliation(s)
- Francisco Javier Sánchez-Martín
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Diana M Lindquist
- Imaging Research Center, Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Julio Landero-Figueroa
- Metallomics Center of the Americas, Department of Chemistry, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Xiang Zhang
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jing Chen
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Kim M Cecil
- Imaging Research Center, Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Mario Medvedovic
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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25
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Meiri D, Marshall CB, Mokady D, LaRose J, Mullin M, Gingras AC, Ikura M, Rottapel R. Mechanistic insight into GPCR-mediated activation of the microtubule-associated RhoA exchange factor GEF-H1. Nat Commun 2014; 5:4857. [PMID: 25209408 DOI: 10.1038/ncomms5857] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 07/31/2014] [Indexed: 12/15/2022] Open
Abstract
The RhoGEF GEF-H1 can be sequestered in an inactive state on polymerized microtubules by the dynein motor light-chain Tctex-1. Phosphorylation of GEF-H1 Ser885 by PKA or PAK kinases creates an inhibitory 14-3-3-binding site. Here we show a new mode of GEF-H1 activation in response to the G-protein-coupled receptor (GPCR) ligands lysophosphatidic acid (LPA) or thrombin that is independent of microtubule depolymerization. LPA/thrombin stimulates disassembly of the GEF-H1:dynein multi-protein complex through the concerted action of Gα and Gβγ. Gα binds directly to GEF-H1 and displaces it from Tctex-1, while Gβγ binds to Tctex-1 and disrupts its interaction with the dynein intermediate chain, resulting in the release of GEF-H1. Full activation of GEF-H1 requires dephosphorylation of Ser885 by PP2A, which is induced by thrombin. The coordinated displacement of GEF-H1 from microtubules by G-proteins and its dephosphorylation by PP2A demonstrate a multistep GEF-H1 activation and present a unique mechanism coupling GPCR signalling to Rho activation.
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Affiliation(s)
- David Meiri
- Department of Biology, Technion Israel Institute of Technology, Haifa 32000, Israel
| | - Christopher B Marshall
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, 101 College Street, Room 12-704, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L7
| | - Daphna Mokady
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, 101 College Street, Room 12-704, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L7
| | - Jose LaRose
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, 101 College Street, Room 12-704, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L7
| | - Michael Mullin
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room 992A, Toronto, Ontario, Canada M5G 1X5
| | - Anne-Claude Gingras
- 1] Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Room 992A, Toronto, Ontario, Canada M5G 1X5 [2] Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Mitsuhiko Ikura
- 1] Princess Margaret Cancer Centre, University Health Network, University of Toronto, 101 College Street, Room 12-704, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L7 [2] Department of Medical Biophysics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Robert Rottapel
- 1] Princess Margaret Cancer Centre, University Health Network, University of Toronto, 101 College Street, Room 12-704, Toronto Medical Discovery Tower, Toronto, Ontario, Canada M5G 1L7 [2] Department of Medical Biophysics, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 [3] Department of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 [4] Department of Immunology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8 [5] Division of Rheumatology, St Michael's Hospital, 30 Bond Street, Toronto, Ontario, Canada M5B 1W8
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Analysis of dynein intermediate chains, light intermediate chains and light chains in a cohort of hereditary peripheral neuropathies. Neurogenetics 2014; 15:229-35. [PMID: 25028179 DOI: 10.1007/s10048-014-0414-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 07/02/2014] [Indexed: 12/23/2022]
Abstract
The cytoplasmic dynein heavy chain (DYNC1H1) gene has been increasingly associated with neurodegenerative disorders including axonal Charcot-Marie-Tooth disease (CMT2), intellectual disability and malformations of cortical development. In addition, evidence from mouse models (Loa, catabolite repressor-activator (Cra) and Sprawling (Swl)) has shown that mutations in Dync1h1 cause a range of neurodegenerative phenotypes with motor and sensory neuron involvement. In this current study, we examined the possible contribution of other cytoplasmic dynein subunits that bind to DYNC1H1 as a cause of inherited peripheral neuropathy. We focused on screening the cytoplasmic dynein intermediate, light intermediate and light chain genes in a cohort of families with inherited peripheral neuropathies. Nine genes were screened and ten variants were detected, but none was identified as pathogenic, indicating that cytoplasmic dynein intermediate, light intermediate and light chains are not a cause of neuropathy in our cohort.
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27
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Blumer JB, Lanier SM. Activators of G protein signaling exhibit broad functionality and define a distinct core signaling triad. Mol Pharmacol 2013; 85:388-96. [PMID: 24302560 DOI: 10.1124/mol.113.090068] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Activators of G protein signaling (AGS), initially discovered in the search for receptor-independent activators of G protein signaling, define a broad panel of biologic regulators that influence signal transfer from receptor to G-protein, guanine nucleotide binding and hydrolysis, G protein subunit interactions, and/or serve as alternative binding partners for Gα and Gβγ independently of the classic heterotrimeric Gαβγ. AGS proteins generally fall into three groups based upon their interaction with and regulation of G protein subunits: group I, guanine nucleotide exchange factors (GEF); group II, guanine nucleotide dissociation inhibitors; and group III, entities that bind to Gβγ. Group I AGS proteins can engage all subclasses of G proteins, whereas group II AGS proteins primarily engage the Gi/Go/transducin family of G proteins. A fourth group of AGS proteins with selectivity for Gα16 may be defined by the Mitf-Tfe family of transcription factors. Groups I-III may act in concert, generating a core signaling triad analogous to the core triad for heterotrimeric G proteins (GEF + G proteins + effector). These two core triads may function independently of each other or actually cross-integrate for additional signal processing. AGS proteins have broad functional roles, and their discovery has advanced new concepts in signal processing, cell and tissue biology, receptor pharmacology, and system adaptation, providing unexpected platforms for therapeutic and diagnostic development.
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Affiliation(s)
- Joe B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina
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28
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IGF-1 activates a cilium-localized noncanonical Gβγ signaling pathway that regulates cell-cycle progression. Dev Cell 2013; 26:358-68. [PMID: 23954591 DOI: 10.1016/j.devcel.2013.07.014] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 05/28/2013] [Accepted: 07/17/2013] [Indexed: 02/03/2023]
Abstract
Primary cilia undergo cell-cycle-dependent assembly and disassembly. Emerging data suggest that ciliary resorption is a checkpoint for S phase reentry and that the activation of phospho(T94)Tctex-1 couples these two events. However, the environmental cues and molecular mechanisms that trigger these processes remain unknown. Here, we show that insulin-like growth-1 (IGF-1) accelerates G1-S progression by causing cilia to resorb. The mitogenic signals of IGF-1 are predominantly transduced through IGF-1 receptor (IGF-1R) on the cilia of fibroblasts and epithelial cells. At the base of the cilium, phosphorylated IGF-1R activates an AGS3-regulated Gβγ signaling pathway that subsequently recruits phospho(T94)Tctex-1 to the transition zone. Perturbing any component of this pathway in cortical progenitors induces premature neuronal differentiation at the expense of proliferation. These data suggest that during corticogenesis, a cilium-transduced, noncanonical IGF-1R-Gβγ-phospho(T94)Tctex-1 signaling pathway promotes the proliferation of neural progenitors through modulation of ciliary resorption and G1 length.
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29
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Dynein Light Chain 1 (DYNLT1) Interacts with Normal and Oncogenic Nucleoporins. PLoS One 2013; 8:e67032. [PMID: 23840580 PMCID: PMC3694108 DOI: 10.1371/journal.pone.0067032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 05/13/2013] [Indexed: 12/18/2022] Open
Abstract
The chimeric oncoprotein NUP98-HOXA9 results from the t(7;11)(p15;p15) chromosomal translocation and is associated with acute myeloid leukemia. It causes aberrant gene regulation and leukemic transformation through mechanisms that are not fully understood. NUP98-HOXA9 consists of an N-terminal portion of the nucleoporin NUP98 that contains many FG repeats fused to the DNA-binding homeodomain of HOXA9. We used a Cytotrap yeast two-hybrid assay to identify proteins that interact with NUP98-HOXA9. We identified Dynein Light Chain 1 (DYNLT1), an integral 14 KDa protein subunit of the large microtubule-based cytoplasmic dynein complex, as an interaction partner of NUP98-HOXA9. Binding was confirmed by in vitro pull down and co-immunoprecipitation assays and the FG repeat region of NUP98-HOXA9 was shown to be essential for the interaction. RNAi-mediated knockdown of DYNLT1 resulted in reduction of the ability of NUP98-HOXA9 to activate transcription and also inhibited the ability of NUP98-HOXA9 to induce proliferation of primary human hematopoietic CD34+ cells. DYNLT1 also showed a strong interaction with wild-type NUP98 and other nucleoporins containing FG repeats. Immunofluorescence analysis showed that DYNLT1 localizes primarily to the nuclear periphery, where it co-localizes with the nuclear pore complex, and to the cytoplasm. Deletion studies showed that the interactions of the nucleoporins with DYNLT1 are dependent predominantly on the C-terminal half of the DYNLT1. These data show for the first time that DYNLT1 interacts with nucleoporins and plays a role in the dysregulation of gene expression and induction of hematopoietic cell proliferation by the leukemogenic nucleoporin fusion, NUP98-HOXA9.
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30
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Yoshida M, Katsuyama S, Tateho K, Nakamura H, Miyoshi J, Ohba T, Matsuhara H, Miki F, Okazaki K, Haraguchi T, Niwa O, Hiraoka Y, Yamamoto A. Microtubule-organizing center formation at telomeres induces meiotic telomere clustering. ACTA ACUST UNITED AC 2013; 200:385-95. [PMID: 23401002 PMCID: PMC3575533 DOI: 10.1083/jcb.201207168] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Telomere-localized SUN and KASH proteins induce formation of a microtubule-based “telocentrosome” that fosters microtubule motor-dependent telomere clustering. During meiosis, telomeres cluster and promote homologous chromosome pairing. Telomere clustering requires the interaction of telomeres with the nuclear membrane proteins SUN (Sad1/UNC-84) and KASH (Klarsicht/ANC-1/Syne homology). The mechanism by which telomeres gather remains elusive. In this paper, we show that telomere clustering in fission yeast depends on microtubules and the microtubule motors, cytoplasmic dynein, and kinesins. Furthermore, the γ-tubulin complex (γ-TuC) is recruited to SUN- and KASH-localized telomeres to form a novel microtubule-organizing center that we termed the “telocentrosome.” Telocentrosome formation depends on the γ-TuC regulator Mto1 and on the KASH protein Kms1, and depletion of either Mto1 or Kms1 caused severe telomere clustering defects. In addition, the dynein light chain (DLC) contributes to telocentrosome formation, and simultaneous depletion of DLC and dynein also caused severe clustering defects. Thus, the telocentrosome is essential for telomere clustering. We propose that telomere-localized SUN and KASH induce telocentrosome formation and that subsequent microtubule motor-dependent aggregation of telocentrosomes via the telocentrosome-nucleated microtubules causes telomere clustering.
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Affiliation(s)
- Masashi Yoshida
- Department of Chemistry, Shizuoka University, Suruga-ku, Shizuoka 422-8529, Japan
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31
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Zheng Z, Wan Q, Liu J, Zhu H, Chu X, Du Q. Evidence for dynein and astral microtubule-mediated cortical release and transport of Gαi/LGN/NuMA complex in mitotic cells. Mol Biol Cell 2013; 24:901-13. [PMID: 23389635 PMCID: PMC3608500 DOI: 10.1091/mbc.e12-06-0458] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Spindle positioning is believed to be governed by the interaction between astral microtubules and the cell cortex and involve cortically anchored motor protein dynein. How dynein is recruited to and regulated at the cell cortex to generate forces on astral microtubules is not clear. Here we show that mammalian homologue of Drosophila Pins (Partner of Inscuteable) (LGN), a Gαi-binding protein that is critical for spindle positioning in different systems, associates with cytoplasmic dynein heavy chain (DYNC1H1) in a Gαi-regulated manner. LGN is required for the mitotic cortical localization of DYNC1H1, which, in turn, also modulates the cortical accumulation of LGN. Using fluorescence recovery after photobleaching analysis, we show that cortical LGN is dynamic and the turnover of LGN relies, at least partially, on astral microtubules and DYNC1H1. We provide evidence for dynein- and astral microtubule-mediated transport of Gαi/LGN/nuclear mitotic apparatus (NuMA) complex from cell cortex to spindle poles and show that actin filaments counteract such transport by maintaining Gαi/LGN/NuMA and dynein at the cell cortex. Our results indicate that astral microtubules are required for establishing bipolar, symmetrical cortical LGN distribution during metaphase. We propose that regulated cortical release and transport of LGN complex along astral microtubules may contribute to spindle positioning in mammalian cells.
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Affiliation(s)
- Zhen Zheng
- Department of Neurology, Medical College of Georgia, Georgia Regents University, Augusta, GA, 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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Meiri D, Marshall CB, Greeve MA, Kim B, Balan M, Suarez F, Bakal C, Wu C, Larose J, Fine N, Ikura M, Rottapel R. Mechanistic insight into the microtubule and actin cytoskeleton coupling through dynein-dependent RhoGEF inhibition. Mol Cell 2012; 45:642-55. [PMID: 22405273 DOI: 10.1016/j.molcel.2012.01.027] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 09/01/2011] [Accepted: 01/20/2012] [Indexed: 11/16/2022]
Abstract
Actin-based stress fiber formation is coupled to microtubule depolymerization through the local activation of RhoA. While the RhoGEF Lfc has been implicated in this cytoskeleton coupling process, it has remained elusive how Lfc is recruited to microtubules and how microtubule recruitment moderates Lfc activity. Here, we demonstrate that the dynein light chain protein Tctex-1 is required for localization of Lfc to microtubules. Lfc residues 139-161 interact with Tctex-1 at a site distinct from the cleft that binds dynein intermediate chain. An NMR-based GEF assay revealed that interaction with Tctex-1 represses Lfc nucleotide exchange activity in an indirect manner that requires both polymerized microtubules and phosphorylation of S885 by PKA. We show that inhibition of Lfc by Tctex-1 is dynein dependent. These studies demonstrate a pivotal role of Tctex-1 as a negative regulator of actin filament organization through its control of Lfc in the crosstalk between microtubule and actin cytoskeletons.
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Affiliation(s)
- David Meiri
- Ontario Cancer Institute and the Campbell Family Cancer Research Institute, 101 College Street, Room 8-703 Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada
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Misfolded Gβ is recruited to cytoplasmic dynein by Nudel for efficient clearance. Cell Res 2012; 22:1140-54. [PMID: 22430153 DOI: 10.1038/cr.2012.41] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The Gβγ heterodimer is an important signal transducer. Gβ, however, is prone to misfolding due to its requirement for Gγ and chaperones for proper folding. How cells dispose of misfolded Gβ (mfGβ) is not clear. Here, we showed that mfGβ was able to be polyubiquitinated and subsequently degraded by the proteasome. It was sequestered in aggresomes after the inhibition of the proteasome activity with MG132. Sustained activation of Gβγ signaling further elevated cellular levels of the ubiquitinated Gβ. Moreover, Nudel, a regulator of cytoplasmic dynein, the microtubule minus end-directed motor, directly interacted with both the unubiquitinated and ubiquitinated mfGβ. Increasing the levels of both mfGβ and Nudel promoted the association of Gβ with both Nudel and dynein, resulting in robust aggresome formation in a dynein-dependent manner. Depletion of Nudel by RNAi reduced the dynein-associated mfGβ, impaired the MG132-induced aggresome formation, and markedly prolonged the half-life of nascent Gβ. Therefore, cytosolic mfGβ is recruited to dynein by Nudel and transported to the centrosome for rapid sequestration and degradation. Such a process not only eliminates mfGβ efficiently for the control of protein quality, but may also help to terminate the Gβγ signaling.
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Blumer JB, Oner SS, Lanier SM. Group II activators of G-protein signalling and proteins containing a G-protein regulatory motif. Acta Physiol (Oxf) 2012; 204:202-18. [PMID: 21615707 DOI: 10.1111/j.1748-1716.2011.02327.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Beyond the core triad of receptor, Gαβγ and effector, there are multiple accessory proteins that provide alternative modes of signal input and regulatory adaptability to G-protein signalling systems. Such accessory proteins may segregate a signalling complex to microdomains of the cell, regulate the basal activity, efficiency and specificity of signal propagation and/or serve as alternative binding partners for Gα or Gβγ independent of the classical heterotrimeric Gαβγ complex. The latter concept led to the postulate that Gα and Gβγ regulate intracellular events distinct from their role as transducers for cell surface seven-transmembrane span receptors. One general class of such accessory proteins is defined by AGS proteins or activators of G-protein signalling that refer to mammalian cDNAs identified in a specific yeast-based functional screen. The discovery of AGS proteins and related entities revealed a number of unexpected mechanisms for regulation of G-protein signalling systems and expanded functional roles for this important signalling system.
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Affiliation(s)
- J B Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, 29425, USA
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36
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Duguay D, Bélanger-Nelson E, Mongrain V, Beben A, Khatchadourian A, Cermakian N. Dynein light chain Tctex-type 1 modulates orexin signaling through its interaction with orexin 1 receptor. PLoS One 2011; 6:e26430. [PMID: 22028875 PMCID: PMC3197643 DOI: 10.1371/journal.pone.0026430] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 09/27/2011] [Indexed: 11/19/2022] Open
Abstract
Orexins (OX-A, OX-B) are neuropeptides involved in the regulation of the sleep-wake cycle, feeding and reward, via activation of orexin receptors 1 and 2 (OX1R, OX2R). The loss of orexin peptides or functional OX2R has been shown to cause the sleep disorder, narcolepsy. Since the regulation of orexin receptors remains largely undefined, we searched for novel protein partners of the intracellular tail of orexin receptors. Using a yeast two-hybrid screening strategy in combination with co-immunoprecipitation experiments, we found interactions between OX1R and the dynein light chains Tctex-type 1 and 3 (Dynlt1, Dynlt3). These interactions were mapped to the C-terminal region of the dynein light chains and to specific residues within the last 10 amino acids of OX1R. Hence, we hypothesized that dynein light chains could regulate orexin signaling. In HEK293 cells expressing OX1R, stimulation with OX-A produced a less sustained extracellular signal-regulated kinases 1/2 (ERK1/2) activation when Dynlt1 was co-expressed, while it was prolonged under reduced Dynlt1 expression. The amount of OX1R located at the plasma membrane as well as the kinetics and extent of OX-A-induced internalization of OX1R (disappearance from membrane) were not altered by Dynlt1. However, Dynlt1 reduced the localization of OX1R in early endosomes following initial internalization. Taken together, these data suggest that Dynlt1 modulates orexin signaling by regulating OX1R, namely its intracellular localization following ligand-induced internalization.
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Affiliation(s)
- David Duguay
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
| | - Erika Bélanger-Nelson
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec, Canada
| | - Valérie Mongrain
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
| | - Anna Beben
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
| | - Armen Khatchadourian
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
| | - Nicolas Cermakian
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec, Canada
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Merino-Gracia J, García-Mayoral MF, Rodríguez-Crespo I. The association of viral proteins with host cell dynein components during virus infection. FEBS J 2011; 278:2997-3011. [PMID: 21777384 PMCID: PMC7164101 DOI: 10.1111/j.1742-4658.2011.08252.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
After fusion with the cellular plasma membrane or endosomal membranes, viral particles are generally too large to diffuse freely within the crowded cytoplasm environment. Thus, they will never reach the cell nucleus or the perinuclear areas where replication or reverse transcription usually takes place. It has been proposed that many unrelated viruses are transported along microtubules in a retrograde manner using the cellular dynein machinery or, at least, some dynein components. A putative employment of the dynein motor in a dynein‐mediated transport has been suggested from experiments in which viral capsid proteins were used as bait in yeast two‐hybrid screens using libraries composed of cellular proteins and dynein‐associated chains were retrieved as virus‐interacting proteins. In most cases DYNLL1, DYNLT1 or DYNLRB1 were identified as the dynein chains that interact with viral proteins. The importance of these dynein–virus interactions has been supported, in principle, by the observation that in some cases the dynein‐interacting motifs of viral proteins altered by site‐directed mutagenesis result in non‐infective virions. Furthermore, overexpression of p50 dynamitin, which blocks the dynein–dynactin interaction, or incubation of infected cells with peptides that compete with viral polypeptides for dynein binding have been shown to alter the viral retrograde transport. Still, it remains to be proved that dynein light chains can bind simultaneously to incoming virions and to the dynein motor for retrograde transport to take place. In this review, we will analyse the association of viral proteins with dynein polypeptides and its implications for viral infection.
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Affiliation(s)
- Javier Merino-Gracia
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense, Madrid, Spain
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Tumor suppressor REIC/Dkk-3 interacts with the dynein light chain, Tctex-1. Biochem Biophys Res Commun 2011; 412:391-5. [DOI: 10.1016/j.bbrc.2011.07.109] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 07/25/2011] [Indexed: 11/19/2022]
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Huang X, Wang HL, Qi ST, Wang ZB, Tong JS, Zhang QH, Ouyang YC, Hou Y, Schatten H, Qi ZQ, Sun QY. DYNLT3 is required for chromosome alignment during mouse oocyte meiotic maturation. Reprod Sci 2011; 18:983-9. [PMID: 21693773 DOI: 10.1177/1933719111401664] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dynein light chain, Tctex-type 3 (DYNLT3), is a member of the cytoplasmic dynein DYNLT light chain family and has been reported to have a potential role in chromosome congression in human mitosis. However, its role in mammalian meiosis is unclear. In this study, we examined its localization, expression, and functions in mouse oocyte meiosis. Immunofluorescent staining showed that DYNLT3 was restricted to the germinal vesicle and associated with kinetochores at the germinal vesicle breakdown stage, metaphase I and metaphase II. The expression level of DYNLT3 was similar at all meiotic stages. Depletion of DYNLT3 by antibody injection resulted in chromosome misalignment and decrease of the polar body extrusion rate. We further found that DYNLT3-depleted oocytes displayed kinetochore-microtubule detachments. Chromosome-spread experiments showed that depletion of DYNLT3 inhibited the metaphase-anaphase transition by preventing homologous chromosome segregation in meiosis I. Our data suggest that DYNLT3 is required for chromosome alignment and homologous chromosome segregation during mouse oocyte meiosis.
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Affiliation(s)
- Xin Huang
- Organ Transplantation Institute, Xiamen University, Xiamen City, Fujian Province, China
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40
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Tctex-1, a novel interaction partner of Rab3D, is required for osteoclastic bone resorption. Mol Cell Biol 2011; 31:1551-64. [PMID: 21262767 DOI: 10.1128/mcb.00834-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Vesicular transport along microtubules must be strictly regulated to sustain the unique structural and functional polarization of bone-resorbing osteoclasts. However, the molecular mechanisms bridging these vesicle-microtubule interactions remain largely obscure. Rab3D, a member of the Rab3 subfamily (Rab3A/B/C/D) of small exocytotic GTPases, represents a core component of the osteoclastic vesicle transport machinery. Here, we identify a new Rab3D-interacting partner, Tctex-1, a light chain of the cytoplasmic dynein microtubule motor complex, by a yeast two-hybrid screen. We demonstrate that Tctex-1 binds specifically to Rab3D in a GTP-dependent manner and co-occupies Rab3D-bearing vesicles in bone-resorbing osteoclasts. Furthermore, we provide evidence that Tctex-1 and Rab3D intimately associate with the dynein motor complex and microtubules in osteoclasts. Finally, targeted disruption of Tctex-1 by RNA interference significantly impairs bone resorption capacity and mislocalizes Rab3D vesicles in osteoclasts, attesting to the notion that components of the Rab3D-trafficking pathway contribute to the maintenance of osteoclastic resorptive function.
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Nyarko A, Barbar E. Light chain-dependent self-association of dynein intermediate chain. J Biol Chem 2011; 286:1556-66. [PMID: 20974845 PMCID: PMC3020764 DOI: 10.1074/jbc.m110.171686] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/15/2010] [Indexed: 11/06/2022] Open
Abstract
Dynein light chains are bivalent dimers that bind two copies of dynein intermediate chain IC to form a cargo attachment subcomplex. The interaction of light chain LC8 with the natively disordered N-terminal domain of IC induces helix formation at distant IC sites in or near a region predicted to form a coiled-coil. This fostered the hypothesis that LC8 binding promotes IC self-association to form a coiled-coil or other interchain helical structure. However, recent studies show that the predicted coiled-coil sequence partially overlaps the light chain LC7 recognition sequence on IC, raising questions about the apparently contradictory effects of LC8 and LC7. Here, we use NMR and fluorescence quenching to localize IC self-association to residues within the predicted coiled-coil that also correspond to helix 1 of the LC7 recognition sequence. LC8 binding promotes IC self-association of helix 1 from each of two IC chains, whereas LC7 binding reverses self-association by incorporating the same residues into two symmetrical, but distant, helices of the LC7-IC complex. Isothermal titration experiments confirm the distinction of LC8 enhancement of IC self-association and LC7 binding effects. When all three light chains are bound, IC self-association is shifted to another region. Such flexibility in association modes may function in maintaining a stable and versatile light chain-intermediate chain assembly under changing cellular conditions.
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Affiliation(s)
- Afua Nyarko
- From the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
| | - Elisar Barbar
- From the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
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Maurice P, Guillaume JL, Benleulmi-Chaachoua A, Daulat AM, Kamal M, Jockers R. GPCR-Interacting Proteins, Major Players of GPCR Function. PHARMACOLOGY OF G PROTEIN COUPLED RECEPTORS 2011; 62:349-80. [DOI: 10.1016/b978-0-12-385952-5.00001-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Tseng YY, Gruzdeva N, Li A, Chuang JZ, Sung CH. Identification of the Tctex-1 regulatory element that directs expression to neural stem/progenitor cells in developing and adult brain. J Comp Neurol 2010; 518:3327-42. [PMID: 20575070 DOI: 10.1002/cne.22402] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previous studies showed that Tctex-1 immunoreactivity is selectively enriched in the germinal zones of adult brain. In this report we identify a regulatory region of the Tctex-1 gene that is capable of directing transgenic expression of green fluorescent protein (GFP) reporter that recapitulates the spatial and temporal expression pattern of endogenous Tctex-1. This construct specifically targeted expression to the nestin(+)/Pax6(+)/GLAST(+) radial glial cells and Tbr2(+) intermediate progenitors when the reporter construct was delivered to developing mouse neocortex via in utero electroporation. Characterization of mice transgenically expressing GFP under the same regulatory element showed that the GFP expression is faithful to endogenous Tctex-1 at the subgranular zone (SGZ) of dentate gyrus, ventricular/subventricular zone of lateral ventricles, and ependymal layer of 3rd ventricle of adult brains. Immunolocalization and bromodeoxyuridine incorporation studies of adult SGZ in four independent mouse lines showed that Tctex-1:GFP reporter selectively marks nestin(+)/GFAP(+)/Sox2(+) neural stem-like cells in two mouse lines (4 and 13). In two other mouse lines (17 and 18), Tctex-1:GFP is selectively expressed in Type-2 and Type-3 transient amplifying progenitors and a small subset of young neuronal progeny. The P/E-Tctex-1 reporter mouse studies independently confirmed the specific enrichment of Tctex-1 at adult SGZ stem/progenitor cells. Furthermore, these studies supported the notion that an analogous transcriptional program may be used to regulate neurogenesis in embryonic cerebral cortex and adult hippocampus. Finally, the genomic sequences and the reporter mouse lines described here provide useful experimental tools to advance adult neural stem cell research.
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Affiliation(s)
- Yun-Yu Tseng
- Margaret M. Dyson Vision Research Institute, Department of Ophthalmology, Weill Medical College of Cornell University, New York, New York 10065, USA
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44
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G-protein β2 subunit interacts with mitofusin 1 to regulate mitochondrial fusion. Nat Commun 2010; 1:101. [PMID: 20981029 DOI: 10.1038/ncomms1099] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Accepted: 09/23/2010] [Indexed: 01/12/2023] Open
Abstract
Mitofusins (Mfns) mediate the fusion of mitochondrial membranes. However, little is known about how Mfns are regulated to control mitochondrial fusion, which is a multistep process requiring tethering and docking of the outer membranes of two mitochondria. In this study, we report that guanine nucleotide binding protein-β subunit 2 (Gβ2), a WD40 repeats protein and a member of the β-subunits of the heterotrimeric G proteins, has a crucial function in mitochondrial fusion. Gβ2 was found to be enriched on the surface of mitochondria and interacted with mitofusin 1 (Mfn1) specifically. Gβ2 also regulated the mobility of Mfn1 on the surface of the mitochondrial membrane and affected the mitochondrial fusion. Depletion of endogenous Gβ2 resulted in mitochondrial fragmentation, which could be rescued by exogenous Gβ2. These findings have thus uncovered a novel role of Gβ2 in regulating mitochondrial fusion through its interaction with Mfn1.
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45
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Eschbach J, Fergani A, Oudart H, Robin JP, Rene F, Gonzalez de Aguilar JL, Larmet Y, Zoll J, Hafezparast M, Schwalenstocker B, Loeffler JP, Ludolph AC, Dupuis L. Mutations in cytoplasmic dynein lead to a Huntington's disease-like defect in energy metabolism of brown and white adipose tissues. Biochim Biophys Acta Mol Basis Dis 2010; 1812:59-69. [PMID: 20887786 DOI: 10.1016/j.bbadis.2010.09.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 09/08/2010] [Accepted: 09/22/2010] [Indexed: 12/21/2022]
Abstract
The molecular motor dynein is regulated by the huntingtin protein, and Huntington's disease (HD) mutations of huntingtin disrupt dynein motor activity. Besides abnormalities in the central nervous system, HD animal models develop prominent peripheral pathology, with defective brown tissue thermogenesis and dysfunctional white adipocytes, but whether this peripheral phenotype is recapitulated by dynein dysfunction is unknown. Here, we observed prominently increased adiposity in mice harboring the legs at odd angles (Loa/+) or the Cramping mutations (Cra/+) in the dynein heavy chain gene. In Cra/+ mice, hyperadiposity occurred in the absence of energy imbalance and was the result of impaired norepinephrine-stimulated lipolysis. A similar phenotype was observed in 3T3L1 adipocytes upon chemical inhibition of dynein showing that loss of functional dynein leads to impairment of lipolysis. Ex vivo, dynein mutant adipose tissue displayed increased reactive oxygen species production that was, at least partially, responsible for the decreased cellular responses to norepinephrine and subsequent defect in stimulated lipolysis. Dynein mutation also affected norepinephrine efficacy to elicit a thermogenic response and led to morphological abnormalities in brown adipose tissue and cold intolerance in dynein mutant mice. Interestingly, protein levels of huntingtin were decreased in dynein mutant adipose tissue. Collectively, our results provide genetic evidence that dynein plays a key role in lipid metabolism and thermogenesis through a modulation of oxidative stress elicited by norepinephrine. This peripheral phenotype of dynein mutant mice is similar to that observed in various animal models of HD, lending further support for a functional link between huntingtin and dynein.
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46
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Oner SS, An N, Vural A, Breton B, Bouvier M, Blumer JB, Lanier SM. Regulation of the AGS3·G{alpha}i signaling complex by a seven-transmembrane span receptor. J Biol Chem 2010; 285:33949-58. [PMID: 20716524 DOI: 10.1074/jbc.m110.138073] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
G-protein signaling modulators (GPSM) play diverse functional roles through their interaction with G-protein subunits. AGS3 (GPSM1) contains four G-protein regulatory motifs (GPR) that directly bind Gα(i) free of Gβγ providing an unusual scaffold for the "G-switch" and signaling complexes, but the mechanism by which signals track into this scaffold are not well understood. We report the regulation of the AGS3·Gα(i) signaling module by a cell surface, seven-transmembrane receptor. AGS3 and Gα(i1) tagged with Renilla luciferase or yellow fluorescent protein expressed in mammalian cells exhibited saturable, specific bioluminescence resonance energy transfer indicating complex formation in the cell. Activation of α(2)-adrenergic receptors or μ-opioid receptors reduced AGS3-RLuc·Gα(i1)-YFP energy transfer by over 30%. The agonist-mediated effects were inhibited by pertussis toxin and co-expression of RGS4, but were not altered by Gβγ sequestration with the carboxyl terminus of GRK2. Gα(i)-dependent and agonist-sensitive bioluminescence resonance energy transfer was also observed between AGS3 and cell-surface receptors typically coupled to Gα(i) and/or Gα(o) indicating that AGS3 is part of a larger signaling complex. Upon receptor activation, AGS3 reversibly dissociates from this complex at the cell cortex. Receptor coupling to both Gαβγ and GPR-Gα(i) offer additional flexibility for systems to respond and adapt to challenges and orchestrate complex behaviors.
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Affiliation(s)
- Sukru Sadik Oner
- Department of Cell and Molecular Pharmacology & Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Vural A, Oner S, An N, Simon V, Ma D, Blumer JB, Lanier SM. Distribution of activator of G-protein signaling 3 within the aggresomal pathway: role of specific residues in the tetratricopeptide repeat domain and differential regulation by the AGS3 binding partners Gi(alpha) and mammalian inscuteable. Mol Cell Biol 2010; 30:1528-40. [PMID: 20065032 PMCID: PMC2832490 DOI: 10.1128/mcb.01018-09] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Revised: 09/10/2009] [Accepted: 12/30/2009] [Indexed: 11/20/2022] Open
Abstract
AGS3, a receptor-independent activator of G-protein signaling, is involved in unexpected functional diversity for G-protein signaling systems. AGS3 has seven tetratricopeptide (TPR) motifs upstream of four G-protein regulatory (GPR) motifs that serve as docking sites for Gialpha-GDP. The positioning of AGS3 within the cell and the intramolecular dynamics between different domains of the proteins are likely key determinants of their ability to influence G-protein signaling. We report that AGS3 enters into the aggresome pathway and that distribution of the protein is regulated by the AGS3 binding partners Gialpha and mammalian Inscuteable (mInsc). Gialpha rescues AGS3 from the aggresome, whereas mInsc augments the aggresome-like distribution of AGS3. The distribution of AGS3 to the aggresome is dependent upon the TPR domain, and it is accelerated by disruption of the TPR organizational structure or introduction of a nonsynonymous single-nucleotide polymorphism. These data present AGS3, G-proteins, and mInsc as candidate proteins involved in regulating cellular stress associated with protein-processing pathologies.
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Affiliation(s)
- Ali Vural
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Sadik Oner
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Ningfei An
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Violaine Simon
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Dzwokai Ma
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Joe B. Blumer
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
| | - Stephen M. Lanier
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106
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Cross talk between Smad, MAPK, and actin in the etiology of pulmonary arterial hypertension. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:265-78. [PMID: 20204736 DOI: 10.1007/978-1-60761-500-2_17] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The gene for the type 2 receptor for the bone morphogenic pathway, BMPR2, is mutated in a large majority of familial pulmonary arterial hypertension (PAH),. However, the mechanisms linking BMPR2 mutation to disease remain obscure. BMPR2 potentially signals through multiple immediate downstream pathways, including Smad, MAPK, LIM domain kinase 1 (LIMK) and dynein, light chain, Tctex-type 1 (TCTEX), v-src sarcoma viral oncogene homolog (SRC), and nuclear factor kappa-B (NFkB). Functional consequences of BMPR2 mutation, largely ascertained from animal models, include a shift from contractile to synthetic phenotype in smooth muscle, probably downstream of Smad signal; alterations in expression of actin organization related genes, possibly related to focal adhesions; alterations in cytokines and inflammatory cell recruitment; increased proliferation and apoptosis; and increased collagen and matrix. A synthesis of the available data suggests that the normal role of BMPR2 in adult animals is to assist in injury repair. BMPR2 is suppressed in injured tissue, which facilitates inflammatory response, shift to a synthetic cellular phenotype, and alterations in migration or permeability of cells in the vascular wall. We thus hypothesize that BMPR2 mutation thus leads to an impaired ability to terminate the injury repair process, leading to strong predisposition to PAH.
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Zhang J, Li S, Musa S, Zhou H, Xiang X. Dynein light intermediate chain in Aspergillus nidulans is essential for the interaction between heavy and intermediate chains. J Biol Chem 2009; 284:34760-8. [PMID: 19837669 DOI: 10.1074/jbc.m109.026872] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytoplasmic dynein is a complex containing heavy chains (HCs), intermediate chains (ICs), light intermediate chains (LICs), and light chains (LCs). The HCs are responsible for motor activity. The ICs at the tail region of the motor interact with dynactin, which is essential for dynein function. However, functions of other subunits and how they contribute to the assembly of the core complex are not clearly defined. Here, we analyzed in the filamentous fungus Aspergillus nidulans functions of the only LIC and two LCs, RobA (Roadblock/LC7) and TctexA (Tctex1) in dynein-mediated nuclear distribution (nud). Whereas the deletion mutant of tctexA did not exhibit an apparent nud mutant phenotype, the deletion mutant of robA exhibited a nud phenotype at an elevated temperature, which is similar to the previously characterized nudG (LC8) deletion mutant. Remarkably, in contrast to the single mutants, the robA and nudG double deletion mutant exhibits a severe nud phenotype at various temperatures. Thus, functions of these two LC classes overlap to some extent, but the presence of both becomes important under specific conditions. The single LIC, however, is essential for dynein function in nuclear distribution. This is evidenced by the identification of the nudN gene as the LIC coding gene, and by the nud phenotype exhibited by the LIC down-regulating mutant, alcA-LIC. Without a functional LIC, the HC-IC association is significantly weakened, and the HCs could no longer accumulate at the microtubule plus end. Thus, the LIC is essential for the assembly of the core complex of dynein in Aspergillus.
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Affiliation(s)
- Jun Zhang
- From the Department of Biochemistry and Molecular Biology, The Uniformed Services University of the Health Sciences-F. Edward Hébert School of Medicine, Bethesda, Maryland 20814, USA
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Modulation of Rho guanine exchange factor Lfc activity by protein kinase A-mediated phosphorylation. Mol Cell Biol 2009; 29:5963-73. [PMID: 19667072 DOI: 10.1128/mcb.01268-08] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Lfc is a guanine nucleotide exchange factor (GEF) for Rho that demonstrates an unusual ability to associate with microtubules. While several phosphorylated residues have been detected in the Lfc polypeptide, the mechanism(s) by which phosphorylation regulates the exchange activity of Lfc remains unclear. We confirm that Lfc is a phosphorylated protein and demonstrate that 14-3-3 interacts directly and in a phosphorylation-dependent manner with Lfc. We identify AKAP121 as an Lfc-binding protein and show that Lfc is phosphorylated in an AKAP-dependent manner by protein kinase A (PKA). Forskolin treatment induced 14-3-3 binding to Lfc and suppressed the exchange activity of wild-type Lfc on RhoA. Importantly, a mutant of Lfc that is unable to associate with 14-3-3 proteins was resistant to inhibition by forskolin. Tctex-1, a dynein motor light chain, binds to Lfc in a competitive manner with 14-3-3.
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