Septins and the Lateral Compartmentalization of Eukaryotic Membranes

Caudron, Fabrice; Barral, Yves

doi:10.1016/j.devcel.2009.04.003

Cited by 280 publications

(265 citation statements)

References 119 publications

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“…The localization of C. reinhardtii septin to the base of the flagella is consistent with a possible role in barrier formation, which has been described to involve a structure known as the "flagellar bracelet" (39,40). Taken together, the in vitro and in vivo data point toward a probable role for CrSEPT in forming homopolymeric filaments that are organized at the base of the flagella to promote barrier formation.…”

Section: Reinhardtii Septin Localizes Mainly At the Base Of The Flsupporting

confidence: 65%

Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii

Pinto

Pereira

Zeraik

et al. 2017

Journal of Biological Chemistry

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Edited by Norma AllewellSeptins are filament-forming GTP-binding proteins involved in many essential cellular events related to cytoskeletal dynamics and maintenance. Septins can self-assemble into heterocomplexes, which polymerize into highly organized, cell membraneinteracting filaments. The number of septin genes varies among organisms, and although their structure and function have been thoroughly studied in opisthokonts (including animals and fungi), no structural studies have been reported for other organisms. This makes the single septin from Chlamydomonas (CrSEPT) a particularly attractive model for investigating whether functional homopolymeric septin filaments also exist. CrSEPT was detected at the base of the flagella in Chlamydomonas, suggesting that CrSEPT is involved in the formation of a membrane-diffusion barrier. Using transmission electron microscopy, we observed that recombinant CrSEPT forms long filaments with dimensions comparable with those of the canonical structure described for opisthokonts. The GTP-binding domain of CrSEPT purified as a nucleotide-free monomer that hydrolyzes GTP and readily binds its analog guanosine 5-3-O-(thio)triphosphate. We also found that upon nucleotide binding, CrSEPT formed dimers that were stabilized by an interface involving the ligand (G-interface). Across this interface, one monomer supplied a catalytic arginine to the opposing subunit, greatly accelerating the rate of GTP hydrolysis. This is the first report of an arginine finger observed in a septin and suggests that CrSEPT may act as its own GTP-activating protein. The finger is conserved in all algal septin sequences, suggesting a possible correlation between the ability to form homopolymeric filaments and the accelerated rate of hydrolysis that it provides.

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Section: Reinhardtii Septin Localizes Mainly At the Base Of The Flsupporting

confidence: 65%

Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii

Pinto

Pereira

Zeraik

et al. 2017

Journal of Biological Chemistry

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“…This expression pattern suggests that SEPT7 may be involved in the regulation of the formation of the midpiece and annulus. Previous studies showed that SEPT1/4/6/7/12 are located at the sperm annulus and that this septin-based organization is a requisite for the structural and functional integrity of sperm [7,8,11,23]. Other proteins located at the mouse sperm annulus include DNAJB13 [24] and testis anion transporter 1 (TAT1) [25].…”

Section: Discussionmentioning

confidence: 99%

The expression pattern of SEPT7 correlates with sperm morphology

Chao

Lin

Kuo

et al. 2010

J Assist Reprod Genet

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Purpose To investigate the expression pattern of the SEPT7 protein during spermatogenesis and its potential role in sperm function. Methods We first investigated the expression pattern of SEPT7 during different steps of mouse spermiogenesis using an immunofluorescence assay (IFA). IFA was also applied to study the expression pattern of SEPT7 in human ejaculated spermatozoa. Nine fertile men with normal semen parameters were used as the control group, and 21 infertile men with asthenozoospermia were recruited as the patient group. We assessed the frequency of the SEPT7 signal in the various morphological subgroups. Results In humans, the frequency of a defective SEPT7 signal was significantly increased in men with asthenozoospermia. The absence of a SEPT7 signal was more prevalent in sperm containing morphological defects of various types. Conclusions The expression pattern of SEPT7 suggested that this protein may be involved in the regulation of subcellular-compartment formation during spermiogenesis in the mouse. The absence of a SEPT7 signal correlated with multiple sperm defects.

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“…First, the septin rings serves as a scaffold for protein-protein interactions to recruit selective proteins at the site (Douglas et al, 2005;McMurray and Thorner, 2009). Second, septin rings function as a diffusion barrier across the plane of the mother-bud neck (Caudron and Barral, 2009). To date, 14 mammalian septin genes (SEPT1-14) have been identified (Cao et al, 2009;McMurray and Thorner, 2009).…”

Section: Introductionmentioning

confidence: 99%

Septin 6 Regulates the Cytoarchitecture of Neurons through Localization at Dendritic Branch Points and Bases of Protrusions

Cho

Lee

Dutta

et al. 2011

Molecules and Cells

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*Septins, a conserved family of GTP-binding proteins with a conserved role in cytokinesis, are present in eukaryotes ranging from yeast to mammals. Septins are also highly expressed in neurons, which are post-mitotic cells. Septin6 (SEPT6) forms SEPT2/6/7 complexes in vivo. In this study, we produced a very specific SEPT6 antibody. Immunocytochemisty (ICC) of dissociated hippocampal cultures revealed that SEPT6 was highly expressed in neurons. Developmentally, the expression of SEPT6 was very low until stage 3 (axonal outgrowth). Significant expression of SEPT6 began at stage 4 (outgrowth of dendrites). At this stage, SEPT6 clusters were positioned at the branch points of developing dendrites. In maturing and mature neurons (stage 5), SEPT6 clusters were positioned at the base of filopodia and spines, and pre-synaptic boutons. Detergent extraction experiments also indicated that SEPT6 is not a post-synaptic density (PSD) protein. Throughout morphologic development of neurons, SEPT6 always formed tiny rings (external diameter, ~0.5 µm), which appear to be clusters at low magnification. When a Sept6 RNAi vector was introduced at the early developmental stage (DIV 2), a significant reduction in dendritic length and branch number was evident. Taken together, our results indicate that SEPT6 begins to be expressed at the stage of dendritic outgrowth and regulates the cytoarchitecture.

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Septins and the Lateral Compartmentalization of Eukaryotic Membranes

Cited by 280 publications

References 119 publications

Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii

Filaments and fingers: Novel structural aspects of the single septin from Chlamydomonas reinhardtii

The expression pattern of SEPT7 correlates with sperm morphology

Septin 6 Regulates the Cytoarchitecture of Neurons through Localization at Dendritic Branch Points and Bases of Protrusions

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