Role of Villin in the Dynamics of Actin Microfilaments

ABSTRACTCandida albicansinvades endothelial cells by binding to N-cadherin and other cell surface receptors. This binding induces rearrangement of endothelial cell actin microfilaments, which results in the formation of pseudopods that surround the organism and pull it into the endothelial cell. Here, we investigated the role of endothelial cell septin 7 (SEPT7) in the endocytosis ofC. albicanshyphae. Using confocal microscopy, we determined that SEPT7 accumulated with N-cadherin and actin microfilaments aroundC. albicansas it was endocytosed by endothelial cells. Affinity purification studies indicated that a complex containing N-cadherin and SEPT7 was recruited byC. albicansand that formation of this complex aroundC. albicanswas mediated by the fungal Als3 and Ssa1 invasins. Knockdown of N-cadherin by small interfering RNA (siRNA) reduced recruitment of SEPT7 toC. albicans, suggesting that N-cadherin functions as a link between SEPT7 and the fungus. Also, depolymerization of actin microfilaments with cytochalasin D decreased the association between SEPT7 and N-cadherin and inhibited recruitment of both SEPT7 and N-cadherin toC. albicans, indicating the necessity of an intact cytoskeleton in the functional interaction between SEPT7 and N-cadherin. Importantly, knockdown of SEPT7 decreased accumulation of N-cadherin aroundC. albicansin intact endothelial cells and reduced binding of N-cadherin to this organism, as revealed by the affinity purification assay. Furthermore, SEPT7 knockdown significantly inhibited the endocytosis ofC. albicans. Therefore, in response toC. albicansinfection, SEPT7 forms a complex with endothelial cell N-cadherin, is required for normal accumulation of N-cadherin aroundC. albicanshyphae, and is necessary for maximal endocytosis of the organism.IMPORTANCEDuring hematogenously disseminated infection,Candida albicansinvades the endothelial cell lining of the blood vessels to invade the deep tissues.C. albicanscan invade endothelial cells by inducing its own endocytosis, which is triggered when theC. albicansAls3 and Ssa1 invasins bind to N-cadherin on the endothelial cell surface. How this binding induces endocytosis is incompletely understood. Septins are intracellular GTP-binding proteins that influence the function and localization of cell surface proteins. We found thatC. albicansAls3 and Ssa1 bind to a complex containing N-cadherin and septin 7, which in turn interacts with endothelial cell microfilaments, thereby inducing endocytosis of the organism. The key role of septin 7 in governing receptor-mediated endocytosis is likely relevant to host cell invasion by other microbial pathogens, in addition toC. albicans.

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The Role of Actin Microfilaments in Depression of Acetylcholine-Induced Currents in Common Snail Neurons in a Cellular Analog of Habituation

Neuroscience and Behavioral Physiology ◽

10.1007/s11055-013-9771-7 ◽

2013 ◽

Vol 43 (5) ◽

pp. 557-564 ◽

Cited By ~ 1

Author(s):

A. S. Pivovarov ◽

N. A. Vasil’eva ◽

G. B. Murzina ◽

D. A. Makhnovskii

Keyword(s):

Common Snail ◽

Actin Microfilaments ◽

Snail Neurons ◽

Induced Currents

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Cytoskeletal arrays in the cells of soybean root nodules: The role of actin microfilaments in the organisation of symbiosomes

PROTOPLASMA ◽

10.1007/bf01279476 ◽

1998 ◽

Vol 203 (3-4) ◽

pp. 194-205 ◽

Cited By ~ 18

Author(s):

Lynne F. Whitehead ◽

David A. Day ◽

Adrienne R. Hardham

Keyword(s):

Root Nodules ◽

Actin Microfilaments ◽

Soybean Root

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Evidence for the participation of actin microfilaments and bristle coats in the internalization of gap junction membrane.

The Journal of Cell Biology ◽

10.1083/jcb.83.3.576 ◽

1979 ◽

Vol 83 (3) ◽

pp. 576-587 ◽

Cited By ~ 121

Author(s):

W J Larsen ◽

H N Tung ◽

S A Murray ◽

C A Swenson

Keyword(s):

Cell Surface ◽

Gap Junction ◽

Granulosa Cells ◽

Actin Microfilaments ◽

Heavy Meromyosin ◽

Thin Sections ◽

En Face ◽

Cytoskeletal Elements ◽

Gap Junctional

Thin sections of rabbit granulosa, human SW-13 adrenal cortical adenocarcinoma, and mouse B-16 melanoma cells revealed an apparent single-layered basket of 4- to 7-nm filaments surrounding cytoplasmic gap junction vesicles. This interpretation was based upon apparent longitudinal, cross, and en face sections of structures surrounding the vesicle profiles in tissue treated with tannic acid-glutaraldehyde. In granulosa cells incubated with the S-1 fragment of heavy meromyosin, arrowhead-decorated filaments were observed at the periphery of the gap junction vesicles, suggesting that these filaments contained actin. In addition, we found that small gap junctional blebs and vesicles at the cell surface were coated with short electron-dense bristles similar in appearance to the cloathrin-containing coat of coated vesicles of nonjunctional membrane. The role of these and other cytoskeletal elements in the possible endocytosis of gap junction membrane is discussed.

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Subcellular distribution of the calcium-storing inositol 1,4,5-trisphosphate-sensitive organelle in rat liver. Possible linkage to the plasma membrane through the actin microfilaments

Biochemical Journal ◽

10.1042/bj2740643 ◽

1991 ◽

Vol 274 (3) ◽

pp. 643-650 ◽

Cited By ~ 96

Author(s):

M F Rossier ◽

G S J Bird ◽

J W Putney

Keyword(s):

Endoplasmic Reticulum ◽

Plasma Membrane ◽

Rat Liver ◽

Binding Sites ◽

Cytochalasin B ◽

Binding Capacity ◽

Spatial Separation ◽

Actin Microfilaments ◽

Inositol 1,4,5 Trisphosphate

The role of Ins(1,4,5)P3 in the mobilization of Ca2+ from intracellular stores of non-muscle cells has been extensively demonstrated; however, the nature of the organelle releasing the Ca2+ is still poorly understood. The distributions of the Ins(1,4,5)P3-binding sites and of the Ins(1,4,5)P3-sensitive Ca2+ pool were investigated in subcellular fractions obtained from rat liver and compared with those of other markers. The Ins(1,4,5)P3-binding vesicles appeared to be completely distinct from the endoplasmic-reticulum-derived microsomes and were enriched in the same fractions which were enriched in alkaline phosphodiesterase I activity. This co-purification of the plasma-membrane marker with the Ins(1,4,5)P3-binding sites was dramatically altered after freezing or after treatment of the homogenate with the microfilament-disruptive drug cytochalasin B, suggesting that the Ins(1,4,5)P3-sensitive organelle may be linked to the plasma membrane through the actin microfilaments. No correlation was observed between the Ins(1,4,5)P3-binding capacity and the portion of the Ca2+ pool that was released by Ins(1,4,5)P3. This may result from the disruption of the native organelle during homogenization, leading to the formation of vesicles containing the Ins(1,4,5)P3 receptor, but lacking the Ca2+ pump. These results are consistent with the idea of a specialized Ins(1,4,5)P3-regulated organelle distinct from the endoplasmic reticulum, and we propose a model of the structural organization of this organelle, in which the anchorage to the cytoskeleton as well as the spatial separation of the Ca2+ pump from the Ins(1,4,5)P3 receptor have important functional significance.

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Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽

10.1001/jama.195.12.1005 ◽

1966 ◽

Vol 195 (12) ◽

pp. 1005-1009 ◽

Cited By ~ 18

Author(s):

D. J. Fernbach

Keyword(s):

Wilms Tumor

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