巻号一覧
37 巻 (2012)
- 2 号 p. 81-
- 1 号 p. 1-
37 巻, 1 号
選択された号の論文の9件中1～9を表示しています
- |<
- <
- 1
- >
- >|
-
Zdenka Drastichova, Jiri Novotny2012 年 37 巻 1 号 p. 1-12
発行日: 2012年
公開日: 2012/01/13
ジャーナル フリー HTMLProtein-protein interactions define specificity in signal transduction and these interactions are central to transmembrane signaling by G-protein-coupled receptors (GPCRs). It is not quite clear, however, whether GPCRs and the regulatory trimeric G-proteins behave as freely and independently diffusible molecules in the plasma membrane or whether they form some preassociated complexes. Here we used clear-native polyacrylamide gel electrophoresis (CN-PAGE) to investigate the presumed coupling between thyrotropin-releasing hormone (TRH) receptor and its cognate Gq/11 protein in HEK293 cells expressing high levels of these proteins. Under different solubilization conditions, the TRH receptor (TRH-R) was identified to form a putative pentameric complex composed of TRH-R homodimer and Gq/11 protein. The presumed association of TRH-R with Gq/11α or Gβ proteins in plasma membranes was verified by RNAi experiments. After 10- or 30-min hormone treatment, TRH-R signaling complexes gradually dissociated with a concomitant release of receptor homodimers. These observations support the model in which GPCRs can be coupled to trimeric G-proteins in preassembled signaling complexes, which might be dynamically regulated upon receptor activation. The precoupling of receptors with their cognate G-proteins can contribute to faster G-protein activation and subsequent signal transfer into the cell interior.
抄録全体を表示PDF形式でダウンロード (1322K) HTML形式で全画面表示 -
Sumio Ishijima2012 年 37 巻 1 号 p. 13-19
発行日: 2012年
公開日: 2012/01/13
[早期公開] 公開日: 2011/11/30ジャーナル フリー HTMLThe change in the flagellar waves of spermatozoa from a tunicate and sea urchins was examined using high-speed video microscopy to clarify the regulation of localized sliding between doublet microtubules in the axoneme. When the tunicate Ciona spermatozoa attached to a coverslip surface by their heads in seawater or they moved in seawater with increased viscosity, the planar waves of the sperm flagella were converted into left-handed helical waves. On the other hand, conversion of the planar waves into helical waves in the sea urchin Hemicentrotus spermatozoa was not seen in seawater with an increased viscosity as well as in ordinary seawater. However, the sea urchin Clypeaster spermatozoa showed the conversion, albeit infrequently, when they thrust their heads into seawater with an increased viscosity. The chirality of the helical waves of the Clypeaster spermatozoa was right-handed. When Ciona spermatozoa swam freely near a glass surface, they moved in relatively large circular paths (yawing motion). There was no difference in the proportion of spermatozoa yawing in either a clockwise or counterclockwise direction when viewed from above, which was also different from that of the sea urchin spermatozoa. These observations suggest that the planar waves generally observed on the sperm flagella are mechanically regulated, although their stability must depend on the Ca2+ concentration in the cell. Furthermore, the chirality of the helical waves may be determined by the intracellular Ca2+ concentration and changed by transmitting the localized active sliding between the doublet microtubules around the axoneme in an alternative direction.
抄録全体を表示PDF形式でダウンロード (1109K) HTML形式で全画面表示 -
Kenji Hayashi, Atsushi Suzuki, Shigeo Ohno2012 年 37 巻 1 号 p. 21-25
発行日: 2012年
公開日: 2012/02/04
[早期公開] 公開日: 2011/12/03ジャーナル フリー HTMLThe serine/threonine kinase, PAR-1, is an essential component of the evolutionary-conserved polarity-regulating system, PAR-aPKC system, which plays indispensable roles in establishing asymmetric protein distributions and cell polarity in various biological contexts (Suzuki, A. and Ohno, S. (2006). J. Cell Sci., 119: 979–987; Matenia, D. and Mandelkow, E.M. (2009). Trends Biochem. Sci., 34: 332–342). PAR-1 is also known as MARK, which phosphorylates classical microtubule-associated proteins (MAPs) and detaches MAPs from microtubules (Matenia, D. and Mandelkow, E.M. (2009). Trends Biochem. Sci., 34: 332–342). This MARK activity of PAR-1 suggests its role in microtubule (MT) dynamics, but surprisingly, only few studies have been carried out to address this issue. Here, we summarize our recent study on live imaging analysis of MT dynamics in PAR-1b-depleted cells, which clearly demonstrated the positive role of PAR-1b in maintaining MT dynamics (Hayashi, K., Suzuki, A., Hirai, S., Kurihara, Y., Hoogenraad, C.C., and Ohno, S. (2011). J. Neurosci., 31: 12094–12103). Importantly, our results further revealed the novel physiological function of PAR-1b in maintaining dendritic spine morphology in mature neurons.
抄録全体を表示PDF形式でダウンロード (4451K) HTML形式で全画面表示 -
Shiva Akhavantabasi, Aysegul Sapmaz, Serkan Tuna, Ayse Elif Erson-Bens ...2012 年 37 巻 1 号 p. 27-38
発行日: 2012年
公開日: 2012/02/04
ジャーナル フリー HTML
電子付録Mounting evidence suggests involvement of deregulated microRNA (miRNA) expression during the complex events of tumorigenesis. Among such deregulated miRNAs in cancer, miR-125b expression is reported to be consistently low in breast cancers. In this study, we screened a panel of breast cancer cell lines (BCCLs) for miR-125b expression and detected decreased expression in 14 of 19 BCCLs. Due to the heterogeneity of breast cancers, MCF7 cells were chosen as a model system for ERBB2 independent breast cancers to restore miR-125b expression (MCF7-125b) to investigate the phenotypical and related functional changes. Earlier, miR-125b was shown to regulate cell motility by targeting ERBB2 in ERBB2 overexpressing breast cancer cells. Here we showed decreased motility and migration in miR-125b expressing MCF7 cells, independent of ERBB2. MCF7-125b cells demonstrated profoundly decreased cytoplasmic protrusions detected by phalloidin staining of filamentous actin along with decreased motility and migration behaviors detected by in vitro wound closure and transwell migration assays compared to empty vector transfected cells (MCF7-EV). Among possible numerous targets of miR-125b, we showed ARID3B (AT-rich interactive domain 3B) to be a novel target with roles in cell motility in breast cancer cells. When ARID3B was transiently silenced, the decreased cell migration was also observed. In light of these findings, miR-125b continues to emerge as an interesting regulator of cancer related phenotypes.
抄録全体を表示PDF形式でダウンロード (1633K) HTML形式で全画面表示 -
Tomoki Nishioka, Masanori Nakayama, Mutsuki Amano, Kozo Kaibuchi2012 年 37 巻 1 号 p. 39-48
発行日: 2012年
公開日: 2012/03/02
[早期公開] 公開日: 2012/01/17ジャーナル フリー HTML
電子付録The small GTPase RhoA is a molecular switch in various extracellular signals. Rho-kinase/ROCK/ROK, a major effector of RhoA, regulates diverse cellular functions by phosphorylating cytoskeletal proteins, endocytic proteins, and polarity proteins. More than twenty Rho-kinase substrates have been reported, but the known substrates do not fully explain the Rho-kinase functions. Herein, we describe the comprehensive screening for Rho-kinase substrates by treating HeLa cells with Rho-kinase and phosphatase inhibitors. The cell lysates containing the phosphorylated substrates were then subjected to affinity chromatography using beads coated with 14-3-3 protein, which interacts with proteins containing phosphorylated serine or threonine residues, to enrich the phosphorylated proteins. The identities of the molecules and phosphorylation sites were determined by liquid chromatography tandem mass spectrometry (LC/MS/MS) after tryptic digestion and phosphopeptide enrichment. The phosphorylated proteins whose phosphopeptide ion peaks were suppressed by treatment with the Rho-kinase inhibitor were regarded as candidate substrates. We identified 121 proteins as candidate substrates. We also identified phosphorylation sites in Partitioning defective 3 homolog (Par-3) at Ser143 and Ser144. We found that Rho-kinase phosphorylated Par-3 at Ser144 both in vitro and in vivo. The method used in this study would be applicable and useful to identify novel substrates of other kinases.
抄録全体を表示PDF形式でダウンロード (1493K) HTML形式で全画面表示 -
Ryota Komori, Mai Taniguchi, Yoshiaki Ichikawa, Aya Uemura, Masaya Oku ...2012 年 37 巻 1 号 p. 49-53
発行日: 2012年
公開日: 2012/03/02
[早期公開] 公開日: 2012/01/17ジャーナル フリー HTMLThe endoplasmic reticulum (ER) stress response is a cytoprotective mechanism against the accumulation of unfolded proteins in the ER (ER stress) that consists of three response pathways (the ATF6, IRE1 and PERK pathways) in mammals. These pathways regulate the transcription of ER-related genes through specific cis-acting elements, ERSE, UPRE and AARE, respectively. Because the mammalian ER stress response is markedly activated in professional secretory cells, its main function was thought to be to upregulate the capacity of protein folding in the ER in accordance with the increased synthesis of secretory proteins. Here, we found that ultraviolet A (UVA) irradiation induced the conversion of an ER-localized sensor pATF6α(P) to an active transcription factor pATF6α(N) in normal human dermal fibroblasts (NHDFs). UVA also induced IRE1-mediated splicing of XBP1 mRNA as well as PERK-mediated phosphorylation of an α subunit of eukaryotic initiation factor 2. Consistent with these observations, we found that UVA increased transcription from ERSE, UPRE and AARE elements. From these results, we concluded that UVA irradiation activates all branches of the mammalian ER stress response in NHDFs. This suggests that the mammalian ER stress response is activated by not only intrinsic stress but also environmental stress.
抄録全体を表示PDF形式でダウンロード (530K) HTML形式で全画面表示 -
Miki Yamamoto-Hino, Masato Abe, Takako Shibano, Yuka Setoguchi, Wakae ...2012 年 37 巻 1 号 p. 55-63
発行日: 2012年
公開日: 2012/03/20
[早期公開] 公開日: 2012/01/17ジャーナル フリー HTMLThe Golgi apparatus is an intracellular organelle playing central roles in post-translational modification and in the secretion of membrane and secretory proteins. These proteins are synthesized in the endoplasmic reticulum (ER) and transported to the cis-, medial-and trans-cisternae of the Golgi. While trafficking through the Golgi, proteins are sequentially modified with glycan moieties by different glycosyltransferases. Therefore, it is important to analyze the glycosylation function of the Golgi at the level of cisternae. Markers widely used for cis-, medial- and trans-cisternae/trans Golgi network (TGN) in Drosophila are GM130, 120 kDa and Syntaxin16 (Syx16); however the anti-120 kDa antibody is no longer available. In the present study, Drosophila Golgi complex-localized glycoprotein-1 (dGLG1) was identified as an antigen recognized by the anti-120 kDa antibody. A monoclonal anti-dGLG1 antibody suitable for immunohistochemistry was raised in rat. Using these markers, the localization of glycosyltransferases and nucleotide-sugar transporters (NSTs) was studied at the cisternal level. Results showed that glycosyltransferases and NSTs involved in the same sugar modification are localized to the same cisternae. Furthermore, valuable functional information was obtained on the localization of novel NSTs with as yet incompletely characterized biochemical properties.
抄録全体を表示PDF形式でダウンロード (4607K) HTML形式で全画面表示 -
Yuji Kamioka, Kenta Sumiyama, Rei Mizuno, Yoshiharu Sakai, Eishu Hirat ...2012 年 37 巻 1 号 p. 65-73
発行日: 2012年
公開日: 2012/03/22
[早期公開] 公開日: 2012/01/24ジャーナル フリー HTML
電子付録Genetically-encoded biosensors based on the principle of Förster resonance energy transfer (FRET) have been widely used in biology to visualize the spatiotemporal dynamics of signaling molecules. Despite the increasing multitude of these biosensors, their application has been mostly limited to cultured cells with transient biosensor expression, due to particular difficulties in the development of transgenic mice that express FRET biosensors. In this study, we report the efficient generation of transgenic mouse lines expressing heritable and functional biosensors for ERK and PKA. These transgenic mice were created by the cytoplasmic co-injection of Tol2 transposase mRNA and a circular plasmid harbouring Tol2 recombination sites. High expression of the biosensors in a wide range of cell types allowed us to screen newborn mice simply by inspection. Observation of these transgenic mice by two-photon excitation microscopy yielded real-time activity maps of ERK and PKA in various tissues, with greatly improved signal-to-background ratios. Our transgenic mice may be bred into diverse genetic backgrounds; moreover, the protocol we have developed paves the way for the generation of transgenic mice that express other FRET biosensors, with important applications in the characterization of physiological and pathological signal transduction events in addition to drug development and screening.
抄録全体を表示PDF形式でダウンロード (12214K) HTML形式で全画面表示 -
Takeshi Nishioka, Amanda Eustace, Catharine West2012 年 37 巻 1 号 p. 75-80
発行日: 2012年
公開日: 2012/03/28
ジャーナル フリー HTMLIn this mini-review, we discuss the physiological and pathological roles of lysyl oxidase (LOX) and its family, LOX-like proteins (LOXL), in relation to prognosis of major cancers. The number of reports on LOX family is numerous. We have decided to review the articles that were recently published (i.e. past 5 years). Experimental techniques in molecular biology have advanced surprisingly in the past decade. Accordingly, the results of the studies are more reliable. Most studies reached the same conclusion; a higher LOX- or LOXL- expression is associated with a poor prognosis. Molecular experiments have already started aiming for clinical application, and the results are encouraging. Suppressing LOX or LOXL activities resulted in lower cell motility in collagen gel and, moreover, succeeded in reducing metastases in mice. LOX family members were originally recognized as molecules that cross-link collagen fibers in the extracellular matrix. Recent studies demonstrated that they are also involved in a phenomenon called Epithelial Mesenchymal Transition (EMT). This may affect cell movement and cancer cell invasiveness. LOX and LOXL2 are regulated by hypoxia, a major factor in the failure of cancer treatment. Here we discuss the molecular biology of the LOX family in relation to its role in tumor biology.
抄録全体を表示PDF形式でダウンロード (212K) HTML形式で全画面表示
- |<
- <
- 1
- >
- >|