title: The differential formation of the LINC-mediated perinuclear actin cap in pluripotent and somatic cells.
abstract: The actin filament cytoskeleton mediates cell motility and adhesion in somatic cells. However, whether the function and organization of the actin network are fundamentally different in pluripotent stem cells is unknown. Here we show that while conventional actin stress fibers at the basal surface of cells are present before and after onset of differentiation of mouse (mESCs) and human embryonic stem cells (hESCs), actin stress fibers of the actin cap, which wrap around the nucleus, are completely absent from undifferentiated mESCs and hESCs and their formation strongly correlates with differentiation. Similarly, the perinuclear actin cap is absent from human induced pluripotent stem cells (hiPSCs), while it is organized in the parental lung fibroblasts from which these hiPSCs are derived and in a wide range of human somatic cells, including lung, embryonic, and foreskin fibroblasts and endothelial cells. During differentiation, the formation of the actin cap follows the expression and proper localization of nuclear lamin A/C and associated linkers of nucleus and cytoskeleton (LINC) complexes at the nuclear envelope, which physically couple the actin cap to the apical surface of the nucleus. The differentiation of hESCs is accompanied by the progressive formation of a perinuclear actin cap while induced pluripotency is accompanied by the specific elimination of the actin cap, and that, through lamin A/C and LINC complexes, this actin cap is involved in progressively shaping the nucleus of hESCs undergoing differentiation. While, the localization of lamin A/C at the nuclear envelope is required for perinuclear actin cap formation, it is not sufficient to control nuclear shape.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Shyam B
authors.initials: SB
authors.lastname: Khatau
authors.forename: Sravanti
authors.initials: S
authors.lastname: Kusuma
authors.forename: Donny
authors.initials: D
authors.lastname: Hanjaya-Putra
authors.forename: Prashant
authors.initials: P
authors.lastname: Mali
authors.forename: Linzhao
authors.initials: L
authors.lastname: Cheng
authors.forename: Jerry S H
authors.initials: JS
authors.lastname: Lee
authors.forename: Sharon
authors.initials: S
authors.lastname: Gerecht
authors.forename: Denis
authors.initials: D
authors.lastname: Wirtz
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D053144:Cell Nucleus Shape; D053595:Embryonic Stem Cells / Q000166:cytology*; D005347:Fibroblasts / Q000166:cytology; D005786:Gene Expression Regulation; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D034904:Lamin Type A / Q000378:metabolism; D008168:Lung / Q000166:cytology; D051379:Mice; D021381:Protein Transport; D022502:Stress Fibers / Q000378:metabolism*
chemical_list: C494847:LMNA protein, human; D034904:Lamin Type A