scholarly journals FIGNL1 associates with KIF1Bβ and BICD1 to restrict dynein transport velocity during axon navigation

2019 ◽  
Vol 218 (10) ◽  
pp. 3290-3306 ◽  
Author(s):  
Melody Atkins ◽  
Laïla Gasmi ◽  
Valérie Bercier ◽  
Céline Revenu ◽  
Filippo Del Bene ◽  
...  

Neuronal connectivity relies on molecular motor-based axonal transport of diverse cargoes. Yet the precise players and regulatory mechanisms orchestrating such trafficking events remain largely unknown. We here report the ATPase Fignl1 as a novel regulator of bidirectional transport during axon navigation. Using a yeast two-hybrid screen and coimmunoprecipitation assays, we showed that Fignl1 binds the kinesin Kif1bβ and the dynein/dynactin adaptor Bicaudal D-1 (Bicd1) in a molecular complex including the dynactin subunit dynactin 1. Fignl1 colocalized with Kif1bβ and showed bidirectional mobility in zebrafish axons. Notably, Kif1bβ and Fignl1 loss of function similarly altered zebrafish motor axon pathfinding and increased dynein-based transport velocity of Rab3 vesicles in these navigating axons, pinpointing Fignl1/Kif1bβ as a dynein speed limiter complex. Accordingly, disrupting dynein/dynactin activity or Bicd1/Fignl1 interaction induced motor axon pathfinding defects characteristic of Fignl1 gain or loss of function, respectively. Finally, pharmacological inhibition of dynein activity partially rescued the axon pathfinding defects of Fignl1-depleted larvae. Together, our results identify Fignl1 as a key dynein regulator required for motor circuit wiring.

2004 ◽  
Vol 15 (7) ◽  
pp. 3073-3082 ◽  
Author(s):  
Denise S. Walker ◽  
Sung Ly ◽  
Nicholas J.D. Gower ◽  
Howard A. Baylis

Inositol-1,4,5-triphosphate receptors (IP3Rs) are ligand-gated Ca2+ channels that control Ca2+ release from intracellular stores. They are central to a wide range of cellular responses. IP3Rs in Caenorhabditis elegans are encoded by a single gene, itr-1, and are widely expressed. Signaling through IP3 and IP3Rs is important in ovulation, control of the defecation cycle, modulation of pharyngeal pumping rate, and embryogenesis. To further elucidate the molecular basis of the diversity of IP3R function, we used a yeast two-hybrid screen to search for proteins that interact with ITR-1. We identified an interaction between ITR-1 and IRI-1, a previously uncharacterized protein with homology to LIN-15B. Iri-1 is widely expressed, and its expression overlaps significantly with that of itr-1. In agreement with this observation, iri-1 functions in known itr-1-mediated processes, namely, upregulation of pharyngeal pumping in response to food and control of the defecation cycle. Knockdown of iri-1 in an itr-1 loss-of-function mutant potentiates some of these effects and sheds light on the signaling pathways that control pharyngeal pumping rate. Knockdown of iri-1 expression also results in a sterile, evl phenotype, as a consequence of failures in early Z1/Z4 lineage divisions, such that gonadogenesis is severely disrupted.


2005 ◽  
Vol 25 (5) ◽  
pp. 1958-1970 ◽  
Author(s):  
Yoshikazu Mikami ◽  
Tetsuya Hori ◽  
Hiroshi Kimura ◽  
Tatsuo Fukagawa

ABSTRACT CENP-H is a constitutive centromere component that localizes to the centromere throughout the cell cycle. Because CENP-H is colocalized with CENP-A and CENP-C, it is thought to be an inner centromere protein. We previously generated a conditional loss-of-function mutant of CENP-H and showed that CENP-H is required for targeting of CENP-C to the centromere in chicken DT40 cells. In the present study, we used this mutant to identify the functional region of chicken CENP-H necessary for centromere targeting and cell viability. This region was found by yeast two-hybrid analysis to interact with Hec1, which is a member of the Nuf2 complex that transiently localizes to the centromere during mitosis. Coimmunoprecipitation experiments revealed that CENP-H interacts with the Nuf2 complex in chicken DT40 cells. Photobleaching experiments showed that both Hec1 and CENP-H form stable associations with the centromeres during mitosis, suggesting that Hec1 acts as a structural component of centromeres during mitosis. On the basis of these results and previously published data, we propose that the Nuf2 complex functions as a connector between the inner and outer kinetochores.


2013 ◽  
Vol 38 (9) ◽  
pp. 1583-1591
Author(s):  
Li-Yan XUE ◽  
Bing LUO ◽  
Li-Quan ZHU ◽  
Yong-Jun YANG ◽  
He-Cui ZHANG ◽  
...  

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
M. V. Borca ◽  
E. A. Vuono ◽  
E. Ramirez-Medina ◽  
P. Azzinaro ◽  
K. A. Berggren ◽  
...  

ABSTRACT The E2 protein in classical swine fever (CSF) virus (CSFV) is the major virus structural glycoprotein and is an essential component of the viral particle. E2 has been shown to be involved in several functions, including virus adsorption, induction of protective immunity, and virulence in swine. Using the yeast two-hybrid system, we previously identified a swine host protein, dynactin subunit 6 (DCTN6) (a component of the cell dynactin complex), as a specific binding partner for E2. We confirmed the interaction between DCTN6 and E2 proteins in CSFV-infected swine cells by using two additional independent methodologies, i.e., coimmunoprecipitation and proximity ligation assays. E2 residues critical for mediating the protein-protein interaction with DCTN6 were mapped by a reverse yeast two-hybrid approach using a randomly mutated E2 library. A recombinant CSFV mutant, E2ΔDCTN6v, harboring specific substitutions in those critical residues was developed to assess the importance of the E2-DCTN6 protein-protein interaction for virus replication and virulence in swine. CSFV E2ΔDCTN6v showed reduced replication, compared with the parental virus, in an established swine cell line (SK6) and in primary swine macrophage cultures. Remarkably, animals infected with CSFV E2ΔDCTN6v remained clinically normal during the 21-day observation period, which suggests that the ability of CSFV E2 to bind host DCTN6 protein efficiently during infection may play a role in viral virulence. IMPORTANCE Structural glycoprotein E2 is an important component of CSFV due to its involvement in many virus activities, particularly virus-host interactions. Here, we present the description and characterization of the protein-protein interaction between E2 and the swine host protein DCTN6 during virus infection. The E2 amino acid residues mediating the interaction with DCTN6 were also identified. A recombinant CSFV harboring mutations disrupting the E2-DCTN6 interaction was created. The effect of disrupting the E2-DCTN6 protein-protein interaction was studied using reverse genetics. It was shown that the same amino acid substitutions that abrogated the E2-DCTN6 interaction in vitro constituted a critical factor in viral virulence in the natural host, domestic swine. This highlights the potential importance of the E2-DCTN6 protein-protein interaction in CSFV virulence and provides possible mechanisms of virus attenuation for the development of improved CSF vaccines.


2002 ◽  
Vol 4 (6) ◽  
pp. 1040-1046 ◽  
Author(s):  
Yasunori Kawagoshi ◽  
Yukiko Tsukagoshi ◽  
Isao Fukunaga

Author(s):  
Orsolya Frittmann ◽  
Vamsi K Gali ◽  
Miklos Halmai ◽  
Robert Toth ◽  
Zsuzsanna Gyorfy ◽  
...  

Abstract DNA damages that hinder the movement of the replication complex can ultimately lead to cell death. To avoid that, cells possess several DNA damage bypass mechanisms. The Rad18 ubiquitin ligase controls error-free and mutagenic pathways that help the replication complex to bypass DNA lesions by monoubiquitylating PCNA at stalled replication forks. In Saccharomyces cerevisiae, two of the Rad18 governed pathways are activated by monoubiquitylated PCNA and they involve translesion synthesis polymerases, whereas a third pathway needs subsequent polyubiquitylation of the same PCNA residue by another ubiquitin ligase the Rad5 protein, and it employs template switching. The goal of this study was to dissect the regulatory role of the multidomain Rad18 in DNA damage bypass using a structure-function based approach. Investigating deletion and point mutant RAD18 variants in yeast genetic and yeast two-hybrid assays we show that the Zn-finger of Rad18 mediates its interaction with Rad5, and the N-terminal adjacent region is also necessary for Rad5 binding. Moreover, results of the yeast two-hybrid and in vivo ubiquitylation experiments raise the possibility that direct interaction between Rad18 and Rad5 might not be necessary for the function of the Rad5 dependent pathway. The presented data also reveal that yeast Rad18 uses different domains to mediate its association with itself and with Rad5. Our results contribute to better understanding of the complex machinery of DNA damage bypass pathways.


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