Tyrosine phosphorylation of cortactin by the FAK-Src complex at focal adhesions regulates cell motility.

BackgroundCell migration plays an important role in many physiological and pathological processes, including immune cell chemotaxis and cancer metastasis. It is a coordinated process that involves dynamic changes in the actin cytoskeleton and its interplay with focal adhesions. At the leading edge of a migrating cell, it is the re-arrangement of actin and its attachment to focal adhesions that generates the driving force necessary for movement. However, the mechanisms involved in the attachment of actin filaments to focal adhesions are still not fully understood.ResultsSignaling by the FAK-Src complex plays a crucial role in regulating the formation of protein complexes at focal adhesions to which the actin filaments are attached. Cortactin, an F-actin associated protein and a substrate of Src kinase, was found to interact with FAK through its SH3 domain and the C-terminal proline-rich regions of FAK. We found that the autophosphorylation of Tyr(397) in FAK, which is necessary for FAK activation, was not required for the interaction with cortactin, but was essential for the tyrosine phosphorylation of the associated cortactin. At focal adhesions, cortactin was phosphorylated at tyrosine residues known to be phosphorylated by Src. The tyrosine phosphorylation of cortactin and its ability to associate with the actin cytoskeleton were required in tandem for the regulation of cell motility. Cell motility could be inhibited by truncating the N-terminal F-actin binding domains of cortactin or by blocking tyrosine phosphorylation (Y421/466/475/482F mutation). In addition, the mutant cortactin phosphorylation mimic (Y421/466/475/482E) had a reduced ability to interact with FAK and promoted cell motility. The promotion of cell motility by the cortactin phosphorylation mimic could also be inhibited by truncating its N-terminal F-actin binding domains.ConclusionsOur results suggest that cortactin acts as a bridging molecule between actin filaments and focal adhesions. The cortactin N-terminus associates with F-actin, while its C-terminus interacts with focal adhesions. The tyrosine phosphorylation of cortactin by the FAK-Src complex modulates its interaction with FAK and increases its turnover at focal adhesions to promote cell motility

ジェンダー化された身体: 『不如帰』におけるジェンダー・パフォーマティビティと疾病

The present study is a textual analysis of Rōka Tokutomi’s novel, The cuckoo (Hototogisu). Under the theoretical framework of Judith Butler’s gender performativity, the study analyzes the intersection of gender, body and illness (wound) in the novel through putting it back into the broader gender discourse of the Meiji Japan. Particularly, this article concentrates on the gendered performance of the four major characters in the novel: Namiko, Takeo, General Kataoka, and widow Kawarashi. The thesis, in brief, is that gender is only performed by the partnered characters through appearance and bodily actions. Comparing the sick body of Namiko and wounded body of Takeo, the author argues that illness or wound plays a significant role in gender performance and illness does not set the patient free from one’s gender obligation. Also, the bifurcation of “women equal to body, men equal to mind” persists in Tukotomi’s narration.Ope

Sina Weibo and its political implications: a case study of the Zhou Yongkang incident

After the Chinese government blocked Facebook in 2008 and Twitter in 2009 in mainland China, perspicacious Chinese Internet service providers have invented alternative social media platforms. Sina Weibo is one of them. Scholars studying the Internet and social media in Western countries have suggested that social media have the potential to construct a unique online public sphere and contribute to a much deeper social change. However, social media and its social and political implications in such a populous developing country with 710 million Internet users have not been thoroughly addressed due to the linguistic estrangement and the firm historical association of the new communication technology with democratic discourse. Furthermore, among the literature studying Chinese Internet, there is a lack of empirical research. The number of studies that look directly into the Chinese social media content is still relatively small. Therefore, this study is an effort to fill this gap through an empirical case study to map out the distinct dynamics in China’s online public sphere facilitated by Sina Weibo. This thesis strives to examine Weibo’s role in facilitating public discussion and constructing an online public sphere in China. To this end, it analyses Sina Weibo users’ discussion about the Zhou Yongkang incident. The theoretical framework applied in this study originates from Habermas’s conception of the public sphere and Warner’s notion of publics. Since these theories formed in Anglophone context, this study focuses on extrapolating the theories into Chinese context. This study uses mixed research methods. It uses both quantitative content analysis and qualitative critical discourse analysis. A wide range of political, social and historical perspectives are also employed to explore the diverse discourse and dynamic interaction on Weibo. Drawing from the public discussion in Zhou’s case, the thesis paints a relatively promising picture of the social media as a platform for personal expression in public discussion on political issues, comparatively jumping out of the discourse agenda set by the government and state media. The interaction among users indicates that rational-critical debate has become a part of China’s online public sphere