The Role of Abp140p in Actin Dynamics of Budding Yeast

Lim, Bum-Soon,Lee, Yong-Keun,Pon, Liza A.,Yang, Hyeong-Cheol Korean Academy of Oral Biology and the UCLA Dental 2005 International Journal of Oral Biology Vol.30 No.1

In the previous studies of Saccharomyces cerevisiae, Abp140p (actin binding protein 140) fused to GFP has been only a protein that can label actin cables of yeast cells so fan However, the role of Abp140p in actin dynamics was remained elusive. In this study, the function of Abp140p was investigated with a deletion mutant and over expression of GFP fused Abp140p. The deletion mutant was slightly more susceptible to Latrunculin-A (Lat-A), an actin-monomer sequestering agent, than wild type, although no significant deformation of actin structures was caused by ABP140 deletion. Over expression of Abp140p-GFP retarded cell growth, and produced thick and robust actin cables. Lat-A was not able to destabilize the thick actin cables, which suggests that actin dynamics was compromised in the cells with surplus of Abp140p. Therefore, Abp140p seems to stabilize actin cables together with other bundling proteins. Recently, actin cable dynamics of budding yeast was found to have a resemblance to that of filopodial tip of cultured mammalian cells. Retrograde movement of actin cables from buds to mother cells indicated local generation of the cable at bud sites. By using Abp140p-GFP, we traced the steps in the generation of a new actin cable after elimination of old cables by sodium azide. Before the appearance of a new actin cable, Abp140p-GFP concentrated in buds and disappeared, as mother cells became abundant in actin cables. Our observations provide a direct evidence of actin cable formation at buds of budding cells.

Novel Macrolide Actin-inhibitors Isolated from Sea Sponges

Karaki, Hideaki,Ozaki, Hiroshi The Korean Society of Toxicology Korea Environment 2001 Toxicological Research Vol.17 No.-

Several marine toxins with macrolide structure have been found to act on actin. One of these toxins is mycalolide B isolated from the genus Mycale. This compound belongs to macrolide antibiotics and consists of tris-oxazole with strong cytotoxic activity ($IC_{50}$: 10-50 nM for growth of L1210 murine leukemia cells). This compound was found to be an actin-depolymerizing agent with the mode of action distinct from that of the known actin inhibitor, cytochalasin D. Tolytoxin, a macrolide isolated from cyano-bacteria with similar chemical structure to mycalolide B, seems to have similar effect. Another macrolide compound, aplyronine A, showed the effects similar to those of mycalolide B. Although bistheonellide A, a dimeric macrolide, did not show a severing effect, it de polymerized F-actin and sequestered G-actin by forming 1 : 2 complex with G-actins. Swinholide A has a structure and effects similar to those of bistheonel-lide A. In conclusion, mycalolide B, tolytoxin, aplyronine A, bistheonellide A and swinholide A are the members of "actin de polymerizing macrolide" the mechanism of which is different from that of cytochalasin D.halasin D.

PRP4 kinase induces actin rearrangement and epithelial-mesenchymal transition through modulation of the actin-binding protein cofilin

Islam, Salman Ul,Ahmed, Muhammad Bilal,Lee, Su Jin,Shehzad, Adeeb,Sonn, Jong Kyung,Kwon, Oh-Shin,Lee, Young Sup Elsevier 2018 Experimental cell research Vol.369 No.1

<P><B>Abstract</B></P> <P>Cell actin cytoskeleton is primarily modulated by Rho family proteins. RhoA regulates several downstream targets, including Rho-associated protein kinase (ROCK), LIM-Kinase (LIMK), and cofilin. Pre-mRNA processing factor 4B (PRP4) modulates the actin cytoskeleton of cancer cells via RhoA activity inhibition. In this study, we discovered that PRP4 over-expression in HCT116 colon cancer cells induces cofilin dephosphorylation by inhibiting the Rho-ROCK-LIMK-cofilin pathway. Two-dimensional gel electrophoresis, and matrix-assisted laser desorption/ionization time-of-flight mass-spectrometry (MALDI-TOF MS) analysis indicated increased expression of protein phosphatase 1A (PP1A) in PRP4-transfected HCT116 cells. The presence of PRP4 increased the expression of PP1A both at the mRNA and protein levels, which possibly activated cofilin through dephosphorylation and subsequently modulated the cell actin cytoskeleton. Furthermore, we found that PRP4 over-expression did not induce cofilin dephosphorylation in the presence of okadaic acid, a potent phosphatase inhibitor. Moreover, we discovered that PRP4 over-expression in HCT116 cells induced dephosphorylation of migration and invasion inhibitory protein (MIIP), and down-regulation of E-cadherin protein levels, which were further restored by the presence of okadaic acid. These findings indicate a possible molecular mechanism of PRP4-induced actin cytoskeleton remodeling and epithelial-mesenchymal transition, and make PRP4 an important target in colon cancer.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PRP4 is involved in pre-mRNA splicing and cell signalling. </LI> <LI> PRP4 modulates the actin cytoskeleton of cancer cells via RhoA activity inhibition. </LI> <LI> PRP4 induces cofilin dephosphorylation by inhibiting the Rho-ROCK-LIMK-cofilin pathway in HCT116 cells. </LI> <LI> Dephosphorylation of cofilin results in F-actin stabilization, re-distribution of cytoplasmic actin, formation of actin stress fibers, and inhibition of cell motility. </LI> <LI> PRP4 over-expression induces the expressions of PP1A, which directly or indirectly dephosphorylates cofilin, resulting in actin cytoskeleton rearrangement, downregulation of E-cadherin, and EMT induction. Cofilin activation may be associated with EMT properties, and promotes the progression of human colon cancer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P> <B>Proposed model for PRP4-induced cofilin and MIIP dephosphorylation and epithelial-mesenchymal transition (EMT) induction</B>. PRP4 over-expression results in cofilin and MIIP dephosphorylation, causing actin dynamics to increase, which may lead to EMT. Another proposed pathway for EMT induction by dephosphorylated MIIP is illustrated in the black-dotted panel. MIIP may inhibit the Rac1 signaling pathway through PAK1 (Rac1 downstream target) binding competition, which results in reduced lamellipodia formation and, finally, EMT.</P> <P>[DISPLAY OMISSION]</P>

Structural and functional characterization of <i>Caenorhabditis elegans</i> α-catenin reveals constitutive binding to β-catenin and F-actin

Kang, Hyunook,Bang, Injin,Jin, Kyeong Sik,Lee, Boyun,Lee, Junho,Shao, Xiangqiang,Heier, Jonathon A.,Kwiatkowski, Adam V.,Nelson, W. James,Hardin, Jeff,Weis, William I.,Choi, Hee-Jung American Society for Biochemistry and Molecular Bi 2017 The Journal of biological chemistry Vol.292 No.17

<P>Intercellular epithelial junctions formed by classical cadherins, beta-catenin, and the actin-binding protein alpha-catenin link the actin cytoskeletons of adjacent cells into a structural continuum. These assemblies transmit forces through the tissue and respond to intracellular and extracellular signals. However, the mechanisms of junctional assembly and regulation are poorly understood. Studies of cadherin-catenin assembly in a number of metazoans have revealed both similarities and unexpected differences in the biochemical properties of the cadherin center dot catenin complex that likely reflect the developmental and environmental requirements of different tissues and organisms. Here, we report the structural and biochemical characterization of HMP-1, the Caenorhabditis elegans alpha-catenin homolog, and compare it with mammalian alpha-catenin. HMP-1 shares overall similarity in structure and actin-binding properties, but displayed differences in conformational flexibility and allosteric regulation from mammalian alpha-catenin. HMP-1 bound filamentous actin with an affinity in the single micromolar range, even when complexed with the beta-catenin homolog HMP-2 or when present in a complex of HMP-2 and the cadherin homolog HMR-1, indicating that HMP-1 binding to F-actin is not allosterically regulated by the HMP-2.HMR-1 complex. The middle (i.e. M) domain of HMP-1 appeared to be less conformationally flexible than mammalian alpha-catenin, which may underlie the dampened effect of HMP-2 binding on HMP-1 actin-binding activity compared with that of the mammalian homolog. In conclusion, our data indicate that HMP-1 constitutively binds beta-catenin and F-actin, and although the overall structure and function of HMP-1 and related alpha-catenins are similar, the vertebrate proteins appear to be under more complex conformational regulation.</P>

Role of Actin Filament on Synaptic Vesicle Pooling in Cultured Hippocampal Neuron

Lee, Se Jeong,Kim, Hyun-Wook,Na, Ji Eun,Kim, DaSom,Kim, Dai Hyun,Ryu, Jae Ryun,Sun, Woong,Rhyu, Im Joo Korean Society of Microscopy 2018 Applied microscopy Vol.48 No.3

The synaptic vesicle is a specialized structure in presynaptic terminals that stores various neurotransmitters. The actin filament has been proposed for playing an important role in mobilizing synaptic vesicles. To understand the role of actin filament on synaptic vesicle pooling, we characterized synaptic vesicles and actin filament after treatment of brain-derived neurotrophic factor (BDNF) or Latrunculin A on primary cultured neuron from rat embryo hippocampus. Western blots revealed that BDNF treatment increased the expression of synapsin I protein, but Latrunculin A treatment decreased the synapsin I protein expression. The increased expression of synapsin I after BDNF disappeared by the treatment of Latrunculin A. Three-dimensional (3D) tomography of synapse showed that more synaptic vesicles localized near the active zone and total number of synaptic vesicles increased after treatment of BDNF. But the number of synaptic vesicle was 2.5-fold reduced in presynaptic terminals and the loss of filamentous network was observed after Latrunculin A application. The treatment of Latruculin A after preincubation of BDNF group showed that synaptic vesicle number was similar to that of control group, but filamentous structures were not restored. These data suggest that the actin filament plays a significant role in synaptic vesicles pooling in presynaptic terminals.

Lamin A/C and Polymeric Actin in Genome Organization

Vladan Ondřej,Emilie Lukášová,Jana Krejčí,Pavel Matula,Stanislav Kozubek 한국분자세포생물학회 2008 Molecules and cells Vol.26 No.4

In this work, we have studied the structural and functional linkage between lamin A/C, nuclear actin, and organization of chromosome territories (CTs) in mammary carcinoma MCF-7 cells. Selective down-regulation of lamin A/C expression led to disruption of the lamin A/C perinuclear layer and disorganization of lamin-bound emerin complexes at the inner nuclear membrane. The silencing of lamin A/C expression resulted in a decrease in the volume and surface area of chromosome territories, especially in chromosomes with high heterochromatin content. Inhibition of actin polymerization led to relaxation of the structure of chromosome territories, and an increase in the volumes and surface areas of the chromosome territories of human chromosomes 1, 2 and 13. The results show an important role of polymeric actin in the organization of the nuclei and the chromosome territories.

Platyconic Acid A의 간성상세포 활성에 대한 억제효과

이기호 충남대학교 약학대학 의약품개발연구소 2018 藥學論文集 Vol.33 No.-

Hepatic stellate cells (HSC) play a key role in the pathogenesis of hepatic fibrosis by producing extra cellular matrix. The degree of hepatic fibrosis depends on the proliferation and activation of HSC and increased net production of collagen. Therefore, inhibition of HSC activation is one of the main ways to block the progression of hepatic fibrosis. Saponins from the roots of Platycodon gran이'florum have shown a variety of pharmacological properties, including anti inflammatory, antioxidant and hepatoprotective properties. However, the effect of platyconic acid A (PCA), a saponin from Platycodon grandJ/lorum on liver fibrosis remains unclear. This study aims to investigate the inhibitory effects of PCA on TGF-131-induced HSC activation. PCA suppressed HSC activation, including TGF-[31-induced proliferation, a-smooth muscle actin (a SMA) and collagen type I expression. These results indicate that PCA can ameliorate hepatic fibrosis by inhibiting the HSC activation.

Characterization of porcine skeletal a-actin gene promoter: expression specificity and regulatory elements

Yujie Zhang,Xu Zhang,Nini Cheng,Yanping Li,Jinyi Xing 한국유전학회 2015 Genes & Genomics Vol.37 No.7

Identification of essential fragments in the promoter region of genes to drive tissue-specific expression of exogenous genes in the skeletal muscle is obligatory for animal transgenic study. The skeletal a-actin is a major protein of the thin filaments of skeletal muscle fiber. In this study, the specificity and activity of porcine skeletal aactin gene promoter were investigated by approaches of cell transfection and assayed with green fluorescent protein (GFP) and dual luciferase reporter activity, respectively. The results revealed that the obtained 3717 bp fragment of porcine skeletal a-actin gene promoter drives GFP to be expressed uniquely in murine C2C12 cells, and two segments of 2.0–2.3 and 0.06–0.37 kb in the promoter region were essential for porcine skeletal a-actin gene expression. The regulatory elements in the 0.06–0.37 kb fragment were further investigated, and when it is deleted or the CArG box within this fragment was mutated, the promoter activity was reduced to 20 or 43 % (P\0.01), respectively, compared to the 3.04 kb segment, suggesting an important role of CArG box in regulating porcine skeletal a-actin gene transcription. The results may provide reference for creating transgenic pigs to express exogenous genes uniquely in pork.

모유두세포의 배양에 관한 연구

심우영(Woo Young Sim),박재경(Jai Kyung Park),허충림(Choong Rim Haw) 대한피부과학회 1995 대한피부과학회지 Vol.33 No.1

Background : Dermal papilla cells, which are mesenchyral components of the hair bulb are considered to play a fundamental role in the inductior hair growth. Objective : We studied how to establish a method of cuku e of dermal papilla cells. Methods : With human scalp tissue, we cultured dermal pipilla cells and identified them under the double-contrat microscopy and observed the epassion of eactin. Results : In vitro they spread slowly, initially as a moayer, and eventually formed multilayered paralled anys. At the edges of expanding colonies the cells were large and flattened and showed a tendency to form clumps. They expressed a-actin which is thought to be a marker of papilla cells, typeIII, typeIV colagen and laminin. Conclusion : These results suggest that using the female papilla cells, specially differentiated fibroblast, may be useful for the study of hau growth. (Kor J Dermatol 1995; 33(1); 28-32)

Schisandra chinensis inhibiting TGFb-induced activation of hepatic stellate cells

신순영,이준호,길하나,정유정,김경란,강길학,임융호 한국응용생명화학회 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.6

Hepatic fibrosis is one of the critical steps contained in the pathogenesis of liver cirrhosis. Excessive deposition of collagen contributes to the development of fibrosis in chronic liver injury. Activation of hepatic stellate cells (HSCs) plays an important role in fibrogenesis and is accountable for providing extracellular matrix components. The berry of Schisandra chinensis has been known to exert hepatoprotective properties. However, its effect on HSCs is not completely understood. Therefore, in this study, we investigated the inhibitory effect of its ethanolic extract (SBE) on hepatic fibrogenesis. We found that SBE treatment effectively reduced the serum levels of alanine aminotransferase and aspartate aminotransferase as well as collagen deposition in the hepatic parenchyma in a thioacetamide-induced hepatic fibrosis mouse model. Moreover, SBE inhibited transforming growth factor b (TGFb)-induced mRNA expression of a-smooth muscle actin (aSMA) and collagen type 1 a1 (COL1A1) in HSCs, suggesting that SBE exerts anti-fibrotic activity by attenuating TGFb-induced HSC activation. To identify the active components of SBE accountable for HSC inhibition, SBE was further partitioned based on the hydrophobicity of the solvents such as water, n-butanol, ethyl acetate, chloroform, and n-hexane. The n-hexane fraction was selected and further separated using analytical high-performance liquid chromatography. We found that six lignans contained in the n-hexane fraction strongly reduced TGFbinduced expression of both aSMA and COL1A1 mRNA. These data suggest that at least six lignans contained in SBE have the strong potential to prevent TGFb-induced HSC activation.