scholarly journals Author response: The role of Cdc42 and Gic1 in the regulation of septin filament formation and dissociation

2013 ◽  
Author(s):  
Yashar Sadian ◽  
Christos Gatsogiannis ◽  
Csilla Patasi ◽  
Oliver Hofnagel ◽  
Roger S Goody ◽  
...  
Keyword(s):  
Author Response ◽  
Filament Formation ◽  
Septin Filament

scholarly journals Functional insight into the role of Orc6 in septin complex filament formation in Drosophila

2015 ◽  
Vol 26 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Katarina Akhmetova ◽  
Maxim Balasov ◽  
Richard P. H. Huijbregts ◽  
Igor Chesnokov
Keyword(s):  
Origin Recognition Complex ◽  
Spatial Organization ◽  
Cell Cortex ◽  
Filament Formation ◽  
Gtp Binding ◽  
Complex Functions ◽  
Septin Filament

Septins belong to a family of polymerizing GTP-binding proteins that are important for cytokinesis and other processes that involve spatial organization of the cell cortex. We reconstituted a recombinant Drosophila septin complex and compared activities of the wild-type and several mutant septin complex variants both in vitro and in vivo. We show that Drosophila septin complex functions depend on the intact GTP-binding and/or hydrolysis domains of Pnut, Sep1, and Sep2. The presence of the functional C-terminal domain of septins is required for the integrity of the complex. Drosophila Orc6 protein, the smallest subunit of the origin recognition complex (ORC), directly binds to septin complex and facilitates septin filament formation. Orc6 forms dimers through the interactions of its N-terminal, TFIIB-like domains. This ability of the protein suggests a direct bridging role for Orc6 in stimulating septin polymerization in Drosophila. Studies reported here provide a functional dissection of a Drosophila septin complex and highlight the basic conserved and divergent features among metazoan septin complexes.

scholarly journals The role of Cdc42 and Gic1 in the regulation of septin filament formation and dissociation

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Yashar Sadian ◽  
Christos Gatsogiannis ◽  
Csilla Patasi ◽  
Oliver Hofnagel ◽  
Roger S Goody ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Scaffolding Protein ◽  
Structural Basis ◽  
Dual Function ◽  
Filament Formation ◽  
Guanine Nucleotide Binding ◽  
Nucleotide Binding Proteins ◽  
Guanine Nucleotide Binding Proteins ◽  
Septin Filament

Septins are guanine nucleotide-binding proteins that polymerize into filamentous and higher-order structures. Cdc42 and its effector Gic1 are involved in septin recruitment, ring formation and dissociation. The regulatory mechanisms behind these processes are not well understood. Here, we have used electron microscopy and cryo electron tomography to elucidate the structural basis of the Gic1-septin and Gic1-Cdc42-septin interaction. We show that Gic1 acts as a scaffolding protein for septin filaments forming long and flexible filament cables. Cdc42 in its GTP-form binds to Gic1, which ultimately leads to the dissociation of Gic1 from the filament cables. Surprisingly, Cdc42-GDP is not inactive, but in the absence of Gic1 directly interacts with septin filaments resulting in their disassembly. We suggest that this unanticipated dual function of Cdc42 is crucial for the cell cycle. Based on our results we propose a novel regulatory mechanism for septin filament formation and dissociation.

scholarly journals The Role of Cdc42 and Gic1 in the Regulation of Septin Filament Formation and Dissociation

2014 ◽  
Vol 106 (2) ◽  
pp. 168a
Author(s):  
Yashar Sadian ◽  
Christos Gatsogiannis ◽  
Csilla Patasi ◽  
Oliver Hofnagel ◽  
Roger S. Goody ◽  
...  
Keyword(s):  
Filament Formation ◽  
Septin Filament

Author response for "The role of galanin in the differentiation of mucosal mast cells in mice"

2019 ◽  
Author(s):  
Tomoko Yamaguchi ◽  
Yumi Ikeda ◽  
Katsuhisa Tashiro ◽  
Yasuyuki Ohkawa ◽  
Kenji Kawabata
Keyword(s):  
Mast Cells ◽  
Author Response ◽  
Mucosal Mast Cells

Author response for "Role of Platelet C‐Type Lectin‐Like Receptor 2 in Promoting Lung Metastasis in Osteosarcoma"

2020 ◽  
Author(s):  
Jiro Ichikawa ◽  
Takashi Ando ◽  
Tomonori Kawasaki ◽  
Tomoyuki Sasaki ◽  
Toshiaki Shirai ◽  
...  
Keyword(s):  
Lung Metastasis ◽  
Author Response

scholarly journals The epigenetic regulator LSH maintains fork protection and genomic stability via MacroH2A deposition and RAD51 filament formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoping Xu ◽  
Kai Ni ◽  
Yafeng He ◽  
Jianke Ren ◽  
Chongkui Sun ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Critical Role ◽  
Genomic Stability ◽  
Dna Degradation ◽  
Replication Forks ◽  
Filament Formation ◽  
Epigenetic Regulator ◽  
Centromeric Instability ◽  
Stalled Replication Forks

AbstractThe Immunodeficiency Centromeric Instability Facial Anomalies (ICF) 4 syndrome is caused by mutations in LSH/HELLS, a chromatin remodeler promoting incorporation of histone variant macroH2A. Here, we demonstrate that LSH depletion results in degradation of nascent DNA at stalled replication forks and the generation of genomic instability. The protection of stalled forks is mediated by macroH2A, whose knockdown mimics LSH depletion and whose overexpression rescues nascent DNA degradation. LSH or macroH2A deficiency leads to an impairment of RAD51 loading, a factor that prevents MRE11 and EXO1 mediated nascent DNA degradation. The defect in RAD51 loading is linked to a disbalance of BRCA1 and 53BP1 accumulation at stalled forks. This is associated with perturbed histone modifications, including abnormal H4K20 methylation that is critical for BRCA1 enrichment and 53BP1 exclusion. Altogether, our results illuminate the mechanism underlying a human syndrome and reveal a critical role of LSH mediated chromatin remodeling in genomic stability.

scholarly journals The role of VPS4 in ESCRT-III polymer remodeling

2019 ◽  
Vol 47 (1) ◽  
pp. 441-448 ◽  
Author(s):  
Christophe Caillat ◽  
Sourav Maity ◽  
Nolwenn Miguet ◽  
Wouter H. Roos ◽  
Winfried Weissenhorn
Keyword(s):  
Active Role ◽  
Mechanistic Models ◽  
Membrane Remodeling ◽  
Filament Formation ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Membrane Fission ◽  
Dynamic Assembly ◽  
Inside Out

Abstract The endosomal sorting complex required for transport-III (ESCRT-III) and VPS4 catalyze a variety of membrane-remodeling processes in eukaryotes and archaea. Common to these processes is the dynamic recruitment of ESCRT-III proteins from the cytosol to the inner face of a membrane neck structure, their activation and filament formation inside or at the membrane neck and the subsequent or concomitant recruitment of the AAA-type ATPase VPS4. The dynamic assembly of ESCRT-III filaments and VPS4 on cellular membranes induces constriction of membrane necks with large diameters such as the cytokinetic midbody and necks with small diameters such as those of intraluminal vesicles or enveloped viruses. The two processes seem to use different sets of ESCRT-III filaments. Constriction is then thought to set the stage for membrane fission. Here, we review recent progress in understanding the structural transitions of ESCRT-III proteins required for filament formation, the functional role of VPS4 in dynamic ESCRT-III assembly and its active role in filament constriction. The recent data will be discussed in the context of different mechanistic models for inside-out membrane fission.

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