title: Interaction between importin 13 and myopodin suggests a nuclear import pathway for myopodin.
abstract: Importin 13 is a member of the importin beta superfamily of nuclear transport proteins and is expressed in multiple tissues at high levels both in humans and rodents, including fetal lung, brain, and heart. In order to elucidate potential functions of imp13 in the heart, we have used rat imp13 as bait to screen a human heart cDNA library and identified an interaction with the C-terminal peptide of myopodin (a.a. 360-698), an actin-bundling protein, associated with tumor-suppressor activity that localizes to both the cytoplasm and the nucleus. We have used GST-pull down assays and co-immunoprecipitation experiments to demonstrate an interaction between imp13 and full-length myopodin and observed that RanGTP dissociates the myopodin-imp13 complex. In studies of cultured cells, we show that both imp13 siRNA and a C-terminal fragment of imp13 protein prevent nuclear localization of myopodin. We, therefore, conclude that imp13 functions in myopodin import and we suggest that the regulation of these events is critical for normal and abnormal cellular differentiation.
authors.affiliation: School of Life Sciences and Key Laboratory for Cell Biology and Tumor Cell Engineering, The Ministry of Education of China, Xiamen University, Xiamen, Fujian, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liang
authors.forename: Guifen
authors.initials: G
authors.lastname: Ke
authors.forename: Wenjun
authors.initials: W
authors.lastname: You
authors.forename: Zi
authors.initials: Z
authors.lastname: Peng
authors.forename: Jie
authors.initials: J
authors.lastname: Lan
authors.forename: Markus
authors.initials: M
authors.lastname: Kalesse
authors.forename: Alan M
authors.initials: AM
authors.lastname: Tartakoff
authors.forename: Feige
authors.initials: F
authors.lastname: Kaplan
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
mesh_terms: D021581:Active Transport, Cell Nucleus; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction / Q000502:physiology*