Dynamin2 and Cortactin Regulate Actin Assembly and Filament Organization

Schafer, Dorothy A.; Weed, Scott A.; Binns, Derk D.; Karginov, Andrei V.; Parsons, J. Thomas; Cooper, John A.

doi:10.1016/s0960-9822(02)01228-9

Cited by 180 publications

(170 citation statements)

References 21 publications

(2 reference statements)

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“…Because cortactin localizes to actin-rich membrane structures such as lamellipodia, podosomes, invadopodia, rocketing endosomes, and CCPs, it has been speculated that cortactin functions to promote F-actin assembly on membranes. In support of this conclusion, Schafer et al (2002) recently showed that cortactin causes association of F-actin bundles with PtdIns(4,5)P 2 -containing liposomes in vitro. Additionally, Cao et al (2003) showed that microinjection of anticortactin antibodies inhibits transferrin uptake, suggesting that cortactin functions in clathrin-mediated endocytosis.…”

Section: Discussionmentioning

confidence: 72%

RNAi-mediated Hip1R Silencing Results in Stable Association between the Endocytic Machinery and the Actin Assembly Machinery

Engqvist-Goldstein

Zhang

Carréno

et al. 2004

MBoC

146

157

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Actin filaments transiently associate with the endocytic machinery during clathrin-coated vesicle formation. Although several proteins that might mediate or regulate this association have been identified, in vivo demonstration of such an activity has not been achieved. Huntingtin interacting protein 1R (Hip1R) is a candidate cytoskeletal-endocytic linker or regulator because it binds to clathrin and actin. Here, Hip1R levels were lowered by RNA interference (RNAi). Surprisingly, rather than disrupting the transient association between endocytic and cytoskeletal proteins, clathrin-coated structures (CCSs) and their endocytic cargo became stably associated with dynamin, actin, the Arp2/3 complex, and its activator, cortactin. RNAi double-depletion experiments demonstrated that accumulation of the cortical actin-endocytic complexes depended on cortactin. Fluorescence recovery after photobleaching showed that dynamic actin filament assembly can occur at CCSs. Our results provide evidence that Hip1R helps to make the interaction between actin and the endocytic machinery functional and transient.

show abstract

Section: Discussionmentioning

confidence: 72%

RNAi-mediated Hip1R Silencing Results in Stable Association between the Endocytic Machinery and the Actin Assembly Machinery

Engqvist-Goldstein

Zhang

Carréno

et al. 2004

MBoC

146

157

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“…32 and 34). Dynamin has also been shown to regulate actin assembly and organization at membranes (42). ARC5 defines a new class of dynamin-like proteins that function specifically in plastid division, and its identification extends the range of cellular processes in which dynamin-like proteins participate.…”

Section: Discussionmentioning

confidence: 99%

ARC5, a cytosolic dynamin-like protein from plants, is part of the chloroplast division machinery

Gao

Kadirjan-Kalbach

Froehlich

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

253

254

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Chloroplast division in plant cells is orchestrated by a complex macromolecular machine with components positioned on both the inner and outer envelope surfaces. The only plastid division proteins identified to date are of endosymbiotic origin and are localized inside the organelle. Employing positional cloning methods in Arabidopsis in conjunction with a novel strategy for pinpointing the mutant locus, we have identified a gene encoding a new chloroplast division protein, ARC5. Mutants of ARC5 exhibit defects in chloroplast constriction, have enlarged, dumbbellshaped chloroplasts, and are rescued by a wild-type copy of ARC5. The ARC5 gene product shares similarity with the dynamin family of GTPases, which mediate endocytosis, mitochondrial division, and other organellar fission and fusion events in eukaryotes. Phylogenetic analysis showed that ARC5 is related to a group of dynamin-like proteins unique to plants. A GFP-ARC5 fusion protein localizes to a ring at the chloroplast division site. Chloroplast import and protease protection assays indicate that the ARC5 ring is positioned on the outer surface of the chloroplast. Thus, ARC5 is the first cytosolic component of the chloroplast division complex to be identified. ARC5 has no obvious counterparts in prokaryotes, suggesting that it evolved from a dynamin-related protein present in the eukaryotic ancestor of plants. These results indicate that the chloroplast division apparatus is of mixed evolutionary origin and that it shares structural and mechanistic similarities with both the cell division machinery of bacteria and the dynamin-mediated organellar fission machineries of eukaryotes.T he chloroplasts of plants and algae are widely believed to have evolved only once from a free-living cyanobacterial endosymbiont (1). Over evolutionary time, many of the genes once present in the endosymbiont have been transferred to the nuclear genome where they have acquired sequences encoding transit peptides that direct their gene products back to the chloroplast (1, 2). This scenario describes the origin of the five previously identified plastid division proteins in plants, all of which evolved from related cell division proteins in cyanobacteria, are encoded in the nucleus, and are localized inside the chloroplast. These include FtsZ1 and FtsZ2, tubulin-like proteins that localize to a ring at the site of plastid constriction (3-10), MinD and MinE, which regulate placement of the plastid division site (11-13), and ARTEMIS, which appears to mediate constriction of the envelope membranes (14).Despite localization of the previously identified plastid division proteins inside the chloroplasts in plant cells, ultrastructural studies have shown that plastid division entails the coordinated activity of components localized outside as well as inside the organelle. In plants, the chloroplast division complex comprises electron-dense structures situated both on the stromal surface of the inner envelope membrane and on the cytosolic surface of the outer membrane (15). These structur...

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“…Dynamin 2-mediated cortactin activation appears to be very modest. Based on the time to induce a half-maximum of actin assembly, dynamin 2 induces a less than 30% increase in the cortactin activity under an optimal condition (Schafer et al, 2002). In the case of Fdg1, a peptide of Fdg1-PRD itself is unable to activate cortactin.…”

Section: Discussionmentioning

confidence: 99%

Differential regulation of cortactin and N-WASP-mediated actin polymerization by missing in metastasis (MIM) protein

et al. 2005

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Dynamin2 and Cortactin Regulate Actin Assembly and Filament Organization

Cited by 180 publications

References 21 publications

RNAi-mediated Hip1R Silencing Results in Stable Association between the Endocytic Machinery and the Actin Assembly Machinery

RNAi-mediated Hip1R Silencing Results in Stable Association between the Endocytic Machinery and the Actin Assembly Machinery

ARC5, a cytosolic dynamin-like protein from plants, is part of the chloroplast division machinery

Differential regulation of cortactin and N-WASP-mediated actin polymerization by missing in metastasis (MIM) protein

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