Septins, which are involved in cytokinesis, have been identified in a variety of fungi and animal cells. For analysis of the function of septin, drugs targeting septin would be useful; however, no such drugs have been available hitherto. By serendipity, we found that forchlorfenuron (FCF, N-(2-chloro-4-pyridyl)-N-phenylurea, 4PU300), a synthetic plant cytokinin, disturbed cytokinesis in Sacchar...

The accumulation of lipid droplets (LD) is frequently observed in hepatitis C virus (HCV) infection and represents an important risk factor for the development of liver steatosis and cirrhosis. The mechanisms of LD biogenesis and growth remain open questions. Here, transcriptome analysis reveals a significant upregulation of septin 9 in HCV-induced cirrhosis compared with the normal liver. HCV ...

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-se...

Septins, cytoskeletal proteins with well-characterised roles in cytokinesis, form cage-like structures around cytosolic Shigella flexneri and promote their targeting to autophagosomes. However, the processes underlying septin cage assembly, and whether they influence S. flexneri proliferation, remain to be established. Using single-cell analysis, we show that the septin cages inhibit S. flexner...

In the yeast Saccharomyces cerevisiae, several components of the septin ring are sumoylated during anaphase and then abruptly desumoylated at cytokinesis. We show that septin sumoylation is controlled by the interactions of two enzymes of the sumoylation pathway, Siz1p and Ulp1p, with the nuclear transport machinery. The E3 ligase Siz1p is imported into the nucleus by the karyopherin Kap95p dur...

Accurate cell division requires the proper assembly of high-order septin structures. In fission yeast (Schizosaccharomyces pombe), Spn1-Spn4 are assembled into a primary septin ring at the division site, and the subsequent recruitment of Mid2 to the structure results in a stable septin ring. However, not much is known about the regulation of this key process. Here, we found that deletion of Spt...

At the beginning of the budding yeast cell cycle, the GTPase Cdc42p promotes the assembly of a ring of septins at the site of future bud emergence. Here, we present an analysis of cdc42 mutants that display specific defects in septin organization, which identifies an important role for GTP hydrolysis by Cdc42p in the assembly of the septin ring. The mutants show defects in basal or stimulated G...

Septin hetero-oligomers polymerize into cytoskeletal filaments with essential functions in many eukaryotic cell types. Mutations within the oligomerization interface that encompasses the GTP-binding pocket of a septin (its "G interface") cause thermoinstability of yeast septin hetero-oligomer assembly, and human disease. When coexpressed with its wild-type counterpart, a G interface mutant is e...

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 ...

Septins are critical for numerous cellular processes through the formation of heteromeric filaments and rings indicating the importance of structural regulators in septin assembly. Several posttranslational modifications (PTMs) mediate the dynamics of septin filaments in yeast. However, little is known about the role of PTMs in regulating mammalian septin assembly, and the in vivo significance ...