title: Novel localization of formin mDia2: importin β-mediated delivery to and retention at the cytoplasmic side of the nuclear envelope.
abstract: The formin family proteins are important regulators of actin polymerization that are involved in many cellular processes. However, little is known about their specific cellular localizations. Here, we show that Diaphanous-related formin-3 (mDia2) localizes to the cytoplasmic side of the nuclear envelope. This localization of mDia2 to the nuclear rim required the presence of a nuclear localization signal (NLS) sequence at the mDia2 N-terminal. Consistent with this result, super-resolution images demonstrated that at the nuclear rim, mDia2 co-localized with the nuclear pore complexes and a nuclear transport receptor, importin β. Furthermore, an interaction between mDia2 and importin β was detected by immunoprecipitation, and silencing of importin β was shown to attenuate accumulation of mDia2 to the nuclear rim. We have shown previously that Ca(2+) entry leads to the assembly of perinuclear actin rim in an inverted formin 2 (INF2) dependent manner. mDia2, however, was not involved in this process since abolishing its localization at the nuclear rim by silencing of importin β had no effect on actin assembly at the nuclear rim triggered by Ca(2+) stimulation.
authors.affiliation: Mechanobiology Institute, National University of Singapore, 117411, Singapore.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Shao
authors.affiliation: Mechanobiology Institute, National University of Singapore, 117411, Singapore Frontiers of Innovative Research in Science and Technology, Konan University, Kobe 650-0047, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kawauchi
authors.affiliation: Mechanobiology Institute, National University of Singapore, 117411, Singapore Department of Biological Sciences, National University of Singapore, 117543, Singapore FIRC Institute of Molecular Oncology, Milan 20139, Italy.
authors.forename: G V
authors.initials: GV
authors.lastname: Shivashankar
authors.affiliation: Mechanobiology Institute, National University of Singapore, 117411, Singapore Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel Alexander.Bershadsky@weizmann.ac.il.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Bershadsky
keywords: Formin mDia2; Importin β; Nuclear rim