title: Emp is a component of the nuclear matrix of mammalian cells and undergoes dynamic rearrangements during cell division.
abstract: Emp, originally detected in erythroblastic islands, is expressed in numerous cell types and tissues suggesting a functionality not limited to hematopoiesis. To study the function of Emp in non-hematopoietic cells, an epitope-tagged recombinant human Emp was expressed in HEK cells. Preliminary studies revealed that Emp partitioned into both the nuclear and Triton X-100-insoluble cytoskeletal fractions in approximately a 4:1 ratio. In this study, we report investigations of Emp in the nucleus. Sequential extractions of interphase nuclei showed that recombinant Emp was present predominantly in the nuclear matrix. Immunofluorescence microscopy showed that Emp was present in typical nuclear speckles enriched with the spliceosome assembly factor SC35 and partially co-localized with actin staining. Coimmunoprecipitation and GST-pull-down assays confirmed the apparent close association of Emp with nuclear actin. During mitosis, Emp was detected at the mitotic spindle/spindle poles, as well as in the contractile ring during cytokinesis. These results suggest that Emp undergoes dynamic rearrangements within the nuclear architecture that are correlated with cell division.
authors.affiliation: Center of Cell Biology, Department of Medicine, Caritas St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA.
authors.forename: Shashi
authors.initials: S
authors.lastname: Bala
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.forename: Shivani
authors.initials: S
authors.lastname: Soni
authors.forename: Sudha
authors.initials: S
authors.lastname: Sinha
authors.forename: Manjit
authors.initials: M
authors.lastname: Hanspal
mesh_terms: D000199:Actins / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D001798:Blood Proteins / Q000378:metabolism*; D015815:Cell Adhesion Molecules; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology* / Q000378:metabolism*; D015530:Nuclear Matrix / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism*
chemical_list: D000199:Actins; D001798:Blood Proteins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; C115214:MAEA protein, human