scholarly journals The PCH family protein, Cdc15p, recruits two F-actin nucleation pathways to coordinate cytokinetic actin ring formation in Schizosaccharomyces pombe

2003 ◽  
Vol 162 (5) ◽  
pp. 851-862 ◽  
Author(s):  
Robert H. Carnahan ◽  
Kathleen L. Gould
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Actin Filaments ◽  
Critical Role ◽  
Ring Formation ◽  
Actin Nucleation ◽  
Actin Ring ◽  
Mutual Dependence ◽  
Family Protein

Cytokinetic actin ring (CAR) formation in Schizosaccharomyces pombe requires two independent actin nucleation pathways, one dependent on the Arp2/3 complex and another involving the formin Cdc12p. Here we investigate the role of the S. pombe Cdc15 homology family protein, Cdc15p, in CAR assembly and find that it interacts with proteins from both of these nucleation pathways. Cdc15p binds directly to the Arp2/3 complex activator Myo1p, which likely explains why actin patches and the Arp2/3 complex fail to be medially recruited during mitosis in cdc15 mutants. Cdc15p also binds directly to Cdc12p. Cdc15p and Cdc12p not only display mutual dependence for CAR localization, but also exist together in a ring-nucleating structure before CAR formation. The disruption of these interactions in cdc15 null cells is likely to be the reason for their complete lack of CARs. We propose a model in which Cdc15p plays a critical role in recruiting and coordinating the pathways essential for the assembly of medially located F-actin filaments and construction of the CAR.

Critical role of cortactin in actin ring formation and osteoclastic bone resorption

2006 ◽  
Vol 24 (5) ◽  
pp. 368-372 ◽  
Author(s):  
Takuma Matsubara ◽  
Akira Myoui ◽  
Fumiyo Ikeda ◽  
Kenji Hata ◽  
Hideki Yoshikawa ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Critical Role ◽  
Ring Formation ◽  
Osteoclastic Bone Resorption ◽  
Actin Ring

scholarly journals Critical role of PP2A-B56 family protein degradation in HIV-1 Vif mediated G2 cell cycle arrest

2020 ◽  
Vol 527 (1) ◽  
pp. 257-263
Author(s):  
Kayoko Nagata ◽  
Keisuke Shindo ◽  
Yusuke Matsui ◽  
Kotaro Shirakawa ◽  
Akifumi Takaori-Kondo
Keyword(s):  
Cell Cycle ◽  
Protein Degradation ◽  
Cell Cycle Arrest ◽  
Critical Role ◽  
Cycle Arrest ◽  
Family Protein ◽  
G2 Cell Cycle Arrest ◽  
Hiv 1

scholarly journals Guanylate-Binding Protein 1 Inhibits Nuclear Delivery of Kaposi's Sarcoma-Associated Herpesvirus Virions by Disrupting Formation of Actin Filament

2017 ◽  
Vol 91 (16) ◽  
Author(s):  
Zhe Zou ◽  
Zhihua Meng ◽  
Chao Ma ◽  
Deguang Liang ◽  
Rui Sun ◽  
...  
Keyword(s):  
Immune System ◽  
Actin Filaments ◽  
Primary Infection ◽  
Rna Viruses ◽  
Critical Role ◽  
Host Cells ◽  
Host Immune System ◽  
Kshv Infection ◽  
Guanylate Binding Protein

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) is a typical gammaherpesvirus that establishes persistent lifelong infection in host cells. In order to establish successful infection, KSHV has evolved numerous immune evasion strategies to bypass or hijack the host immune system. However, host cells still produce immune cytokines abundantly during primary KSHV infection. Whether the immune effectors produced are able to inhibit viral infection and how KSHV successfully conquers these immune effectors remain largely unknown. The guanylate-binding protein 1 (GBP1) gene is an interferon-stimulated gene and exerts antiviral functions on several RNA viruses; however, its function in DNA virus infection is less well understood. In this study, we found that KSHV infection increases both the transcriptional and protein levels of GBP1 at the early stage of primary infection by activating the NF-κB pathway. The overexpression of GBP1 significantly inhibited KSHV infection, while the knockdown of GBP1 promoted KSHV infection. The GTPase activity and dimerization of GBP1 were demonstrated to be responsible for its anti-KSHV activity. Furthermore, we found that GBP1 inhibited the nuclear delivery of KSHV virions by disrupting the formation of actin filaments. Finally, we demonstrated that replication and transcription activator (RTA) promotes the degradation of GBP1 through a proteasome pathway. Taken together, these results provide a new understanding of the antiviral mechanism of GBP1, which possesses potent anti-KSHV activity, and suggest the critical role of RTA in the evasion of the innate immune response during primary infection by KSHV. IMPORTANCE GBP1 can be induced by various cytokines and exerts antiviral activities against several RNA viruses. Our study demonstrated that GBP1 can exert anti-KSHV function by inhibiting the nuclear delivery of KSHV virions via the disruption of actin filaments. Moreover, we found that KSHV RTA can promote the degradation of GBP1 through a proteasome-mediated pathway. Taken together, our results elucidate a novel mechanism of GBP1 anti-KSHV activity and emphasize the critical role of RTA in KSHV evasion of the host immune system during primary infection.

Mobility of alpha-actinin along growing actin filaments might affect the cellular chirality

2021 ◽  
pp. 1-14
Author(s):  
Xi Li ◽  
Bin Chen
Keyword(s):  
Actin Filaments ◽  
Critical Role ◽  
Axial Direction ◽  
Biomechanical Properties ◽  
Model Analysis ◽  
Elastic Response ◽  
Cell Phenotype ◽  
Radial Fiber ◽  
Proper Functions

Abstract Chirality is a widespread feature existing in nature and can be critical in the proper functions of some organisms. In our previous work, a rotational clutch-filament model for a radial fiber was built to reveal the critical role of α-actinin in the cellular chiral swirling. Here we assume two mobility modes of α-actinin along actin filaments. In Mode A, where α-actinin concomitantly moves together with a growing filament, our model analysis suggests that cells cannot swirl clockwise; in Mode B, where α-actinin is fixed along the axial direction of the radial fiber instead, our model analysis suggests that both counter-clockwise and clockwise chiral swirling occur, in consistency with experiments. Thus, our studies suggest that how α-actinin moves along growing filaments within a radial fiber would strongly affect cellular swirling. In addition, the previous rotational clutch-model has been improved by considering the elastic response of a radial fiber to a torque and distributed biomechanical properties of varied cell phenotype.

A novel regulatory role of TRAPPC9 in L‐plastin‐mediated osteoclast actin ring formation

2019 ◽  
Vol 121 (1) ◽  
pp. 284-298
Author(s):  
Nazar J. Hussein ◽  
Thomas Mbimba ◽  
Asaad A. Al‐Adlaan ◽  
Mohammad Y. Ansari ◽  
Fatima A. Jaber ◽  
...  
Keyword(s):  
Ring Formation ◽  
Regulatory Role ◽  
Actin Ring

Septins promote F-actin ring formation by crosslinking actin filaments into curved bundles

2014 ◽  
Vol 16 (4) ◽  
pp. 322-334 ◽  
Author(s):  
Manos Mavrakis ◽  
Yannick Azou-Gros ◽  
Feng-Ching Tsai ◽  
José Alvarado ◽  
Aurélie Bertin ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Ring Formation ◽  
Actin Ring

scholarly journals Pivotal role of VASP in Arp2/3 complex–mediated actin nucleation, actin branch-formation, and Listeria monocytogenes motility

2001 ◽  
Vol 155 (1) ◽  
pp. 89-100 ◽  
Author(s):  
Justin Skoble ◽  
Victoria Auerbuch ◽  
Erin D. Goley ◽  
Matthew D. Welch ◽  
Daniel A. Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Actin Filament ◽  
Actin Filaments ◽  
Actin Monomer ◽  
Wild Type ◽  
Binding Region ◽  
Actin Nucleation ◽  
Branch Formation

The Listeria monocytogenes ActA protein mediates actin-based motility by recruiting and stimulating the Arp2/3 complex. In vitro, the actin monomer-binding region of ActA is critical for stimulating Arp2/3-dependent actin nucleation; however, this region is dispensable for actin-based motility in cells. Here, we provide genetic and biochemical evidence that vasodilator-stimulated phosphoprotein (VASP) recruitment by ActA can bypass defects in actin monomer-binding. Furthermore, purified VASP enhances the actin-nucleating activity of wild-type ActA and the Arp2/3 complex while also reducing the frequency of actin branch formation. These data suggest that ActA stimulates the Arp2/3 complex by both VASP-dependent and -independent mechanisms that generate distinct populations of actin filaments in the comet tails of L. monocytogenes. The ability of VASP to contribute to actin filament nucleation and to regulate actin filament architecture highlights the central role of VASP in actin-based motility.

scholarly journals Cortical flow aligns actin filaments to form a furrow

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Anne-Cecile Reymann ◽  
Fabio Staniscia ◽  
Anna Erzberger ◽  
Guillaume Salbreux ◽  
Stephan W Grill
Keyword(s):  
Actin Filaments ◽  
Network Architecture ◽  
Ring Formation ◽  
Material Parameters ◽  
C Elegans ◽  
Physical Mechanisms ◽  
Ring Assembly ◽  
Quantitative Level ◽  
Flow Alignment

Cytokinesis in eukaryotic cells is often accompanied by actomyosin cortical flow. Over 30 years ago, Borisy and White proposed that cortical flow converging upon the cell equator compresses the actomyosin network to mechanically align actin filaments. However, actin filaments also align via search-and-capture, and to what extent compression by flow or active alignment drive furrow formation remains unclear. Here, we quantify the dynamical organization of actin filaments at the onset of ring assembly in the C. elegans zygote, and provide a framework for determining emergent actomyosin material parameters by the use of active nematic gel theory. We characterize flow-alignment coupling, and verify at a quantitative level that compression by flow drives ring formation. Finally, we find that active alignment enhances but is not required for ring formation. Our work characterizes the physical mechanisms of actomyosin ring formation and highlights the role of flow as a central organizer of actomyosin network architecture.

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