Regulation of actin polymerization by villin, a 95,000 dalton cytoskeletal component of intestinal brush borders

Craig, Susan W.; Powell, Leland D.

doi:10.1016/0092-8674(80)90550-4

Cited by 140 publications

(91 citation statements)

References 21 publications

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“…Generally, Villin 2 protein is called ezrin, and it is one the proteins that belong to ezrin-radixin-moesin (ERM) cytoskeleton-associated protein family (13)(14)(15). Villin 2 provides a crucial morphological link between the cell plasma membrane and the http://bmbreports.org BMB reports actin-based cytoskeleton (16,17), maintaining cell shape and polarity, and participating in cell migration, signaling, growth regulation, and differentiation (18,19). Also, Villin 2 interacts with membrane proteins such as CD44, CD43, intercellular adhesion molecule-1 and -2, and phosphatidylinositol [4,5]-biosphosphate, controlling cell adhesion (18,(20)(21)(22)(23)(24).…”

Section: Functional Analysis Of Villin 2 Proteinmentioning

confidence: 99%

Functional study of Villin 2 protein expressed in longissimus dorsi muscle of Korean native cattle in different growth stages

Jin

Han²,

Xu³

et al. 2012

BMB Reports

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The aim of this study was to investigate protein profiles related to the induction of adipogenesis within the bovine longissimus dorsi muscle (BLDM) by proteomic analysis. We analyzed BLDM proteins at different growth stages to clarify the physiological mechanisms of marbled muscle development in 20 head of Korean native cattle (11 month: 10 head, 17 month: 10 head). BLDM proteins were analyzed by two-dimensional electrophoresis and image analysis. Villin 2 was specifically identified by mass spectrometry and a protein search engine. Villin 2 protein expression in BLDM decreased during the fat development stage in test steers. In a Western blot cell culture study of spontaneously immortal bovine muscle fibroblasts, the abundance of Villin 2 was shown to be down-regulated during differentiation into muscle. In 3T3-L1 mouse embryonic fibroblasts, Villin 2 was decreased during differentiation into adipocytes. The results suggest that Villin 2 may be related to the induction of transdifferentiation and adipogenesis in bovine longissimus dorsi muscle. [BMB reports 2012; 45(2): 102-107]

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Section: Functional Analysis Of Villin 2 Proteinmentioning

confidence: 99%

Functional study of Villin 2 protein expressed in longissimus dorsi muscle of Korean native cattle in different growth stages

Jin

Han²,

Xu³

et al. 2012

BMB Reports

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“…3) (24)(25)(26)(27)(28)(29) to be mediated at least in part by the 95-kDal protein, occurs no differently in microvilli from rachitic chicks (Fig. 4).…”

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confidence: 97%

“…With the assumption that the 42-to 45-kDal protein is bonafide actin, the results of Wilson and Lawson (20,21) are of considerable interest from the standpoint of both the action of 1,25-dihydroxyvitamin D3 on calcium transport and the potential effect of the vitamin D hormone on the structure and behavior of the microvillar cytoskeleton. The role of calcium in the regulation of brush border contractility (22), brush border myosin phosphorylation (23), and the length and bundling of microvillar actin filaments (24)(25)(26)(27)(28)(29) has been established. Also, the microvillus contains considerable amounts of calmodulin (30), for which only one function, activation of the' brush border myosin light chain kinase (23), has as yet been defined.…”

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Analysis of cytoskeletal proteins and Ca ²⁺ -dependent regulation of structure in intestinal brush borders from rachitic chicks

Howe

Keller

Mooseker

et al. 1982

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

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We have investigated several structural aspects of-the intestinal epithelial brush border from rachitic chicks. At both the light and electron microscope levels, rachitic brush borders are indistinguishable from controls. Although several of the prominent periodic acid-Schiff-positive proteins ofthe brush border membrane have slightly slower mobilities on sodium dodecyl sulfate/polyacrylamide gels than do corresponding proteins from control brush borders, the major components of the microvillus core, including subunits of 105, 95, and 68 roid, and these molecular events appear to involve both protein synthetic and non-protein-synthetic events.Wilson and Lawson (20) reported effects of vitamin D that may specifically involve the cytoskeletal structure of the brush border. They showed that an early response of rachitic chicks to an acute dose of 1,25-dihydroxyvitamin D3 is the increased rate of synthesis of a 42-to 45-kilodalton (kDal) microvillar protein. This protein was later tentatively identified as f3-and yactin (21). Whether there is an increased turnover or de novo synthesis of the actin-like protein had not been clarified. With the assumption that the 42-to 45-kDal protein is bonafide actin, the results of Wilson and Lawson (20,21) are of considerable interest from the standpoint of both the action of 1,25-dihydroxyvitamin D3 on calcium transport and the potential effect of the vitamin D hormone on the structure and behavior of the microvillar cytoskeleton. The role of calcium in the regulation of brush border contractility (22), brush border myosin phosphorylation (23), and the length and bundling of microvillar actin filaments (24-29) has been established. Also, the microvillus contains considerable amounts of calmodulin (30), for which only one function, activation of the' brush border myosin light chain kinase (23), has as yet been defined. Thus, the significance of calcium in the modulation and regulation of the transmural flow of calcium through the intestinal epithelial cell constituted the basis for the present investigation. The main objective was to determine whether vitamin D alters some of the known molecular components of the microvillus cytoskeleton, and thus to provide the basis for further studies on the relationships among the cytoskeleton ofthe brush border, vitamin D, and calcium transport. Other observations on the protein components of the brush border are reported herein. A review of brush border structure and function has recently appeared (31).MATERIALS AND METHODS Animals. White Leghorn cockerels were maintained on a rachitogenic diet (32) in a room with incandescent lighting for 4-5 weeks. Some chicks were injected with 500 international units of vitamin D3 at least 72 hr before the experiments were performed and fed a vitamin D-complete 'diet; these chicks served as vitamin D replete controls. To verify the vitamin D status of animals, radial immunoassays for vitamin D-dependent calcium-binding protein were performed as described (33) on supernates saved from the first...

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“…Unfortunately, A c has not yet been measured in cells and has only been estimated by very indirect methods in cell extracts (1). In vitro methods have been developed that allow for the measurement of F-actin using birefringence (2), viscosity (3), light scattering (4), centrifugation (5), binding of labeled phalloidin (6), or the fluorescence of pyrenyl-labeled actin (7). Other methods such as the DNase I binding assay yield the sum of A c and an indeterminate fraction of sequestered actin monomer (8).…”

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confidence: 99%

Effects of Profilin and Thymosin β4 on the Critical Concentration of Actin Demonstrated in Vitro and in Cell Extracts with a Novel Direct Assay

Yarmola

Bubb

2004

Journal of Biological Chemistry

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The free actin concentration at steady state, A c , is a variable that determines how actin regulatory proteins influence the extent of actin polymerization. We describe a novel method employing fluorescence anisotropy to directly measure A c in any sample after the addition of a trace amount of labeled thymosin ␤ 4 or thymosin ␤ 4 peptide. Using this assay, we confirm earlier theoretical work on the helical polymerization of actin and confirm the effects of actin filament-stabilizing drugs and capping proteins on A c , thereby validating the assay. We also confirm a controversial prior observation that profilin lowers the critical concentration of Mg 2؉ -actin. A general mechanism is proposed to explain this effect, and the first quantitative dose-response curve for the effect of profilin on A c facilitates its evaluation. This mechanism also predicts the effect of profilin on critical concentration in the presence of the limited amount of capping protein, which is the condition often found in cells, and the effect of profilin on critical concentration in cell extracts is demonstrated for the first time. Additionally, nonlinear effects of thymosin ␤ 4 on the steady state amount of F-actin are explained by the observed changes in A c . This assay has potential in vivo applications that complement those demonstrated in vitro.Total cellular actin is equal to the sum of the concentration of free monomer (the critical concentration, A c ), the concentration of unpolymerized actin sequestered by various actin-binding proteins, and the concentration of actin polymer or F-actin. Changes in A c induced by actin regulatory proteins influence actin polymer dynamics by an amplification mechanism that results in large changes in the amount of sequestered, unpolymerized actin. Quantitative evaluation of models of cytoskeletal function requires accurate knowledge of the value of A c . Unfortunately, A c has not yet been measured in cells and has only been estimated by very indirect methods in cell extracts (1). In vitro methods have been developed that allow for the measurement of F-actin using birefringence (2), viscosity (3), light scattering (4), centrifugation (5), binding of labeled phalloidin (6), or the fluorescence of pyrenyl-labeled actin (7). Other methods such as the DNase I binding assay yield the sum of A c and an indeterminate fraction of sequestered actin monomer (8). Clever uses of combinations of data have in some cases allowed investigators to subtract F-actin content from total actin and then fractionate the contributions of A c and monomer sequestration (9, 10), but the results have proven controversial (11,12).Based on theoretical considerations, the critical concentration is expected to be equal to the ratio of the rate constants of association and dissociation of actin subunits from actin filaments. Measurement of these rate constants using a method such as electron microscopy can be used to indirectly evaluate A c , assuming the applicability of the theory (13,14). However, the participation of actin b...

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Regulation of actin polymerization by villin, a 95,000 dalton cytoskeletal component of intestinal brush borders

Cited by 140 publications

References 21 publications

Functional study of Villin 2 protein expressed in longissimus dorsi muscle of Korean native cattle in different growth stages

Functional study of Villin 2 protein expressed in longissimus dorsi muscle of Korean native cattle in different growth stages

Analysis of cytoskeletal proteins and Ca ²⁺ -dependent regulation of structure in intestinal brush borders from rachitic chicks

Effects of Profilin and Thymosin β4 on the Critical Concentration of Actin Demonstrated in Vitro and in Cell Extracts with a Novel Direct Assay

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Regulation of actin polymerization by villin, a 95,000 dalton cytoskeletal component of intestinal brush borders

Cited by 140 publications

References 21 publications

Functional study of Villin 2 protein expressed in longissimus dorsi muscle of Korean native cattle in different growth stages

Functional study of Villin 2 protein expressed in longissimus dorsi muscle of Korean native cattle in different growth stages

Analysis of cytoskeletal proteins and Ca 2+ -dependent regulation of structure in intestinal brush borders from rachitic chicks

Effects of Profilin and Thymosin β4 on the Critical Concentration of Actin Demonstrated in Vitro and in Cell Extracts with a Novel Direct Assay

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Analysis of cytoskeletal proteins and Ca ²⁺ -dependent regulation of structure in intestinal brush borders from rachitic chicks