title: Matrix elasticity regulates lamin-A,C phosphorylation and turnover with feedback to actomyosin.
abstract: Tissue microenvironments are characterized not only in terms of chemical composition but also by collective properties such as stiffness, which influences the contractility of a cell, its adherent morphology, and even differentiation. The nucleoskeletal protein lamin-A,C increases with matrix stiffness, confers nuclear mechanical properties, and influences differentiation of mesenchymal stem cells (MSCs), whereas B-type lamins remain relatively constant. Here we show in single-cell analyses that matrix stiffness couples to myosin-II activity to promote lamin-A,C dephosphorylation at Ser22, which regulates turnover, lamina physical properties, and actomyosin expression. Lamin-A,C phosphorylation is low in interphase versus dividing cells, and its levels rise with states of nuclear rounding in which myosin-II generates little to no tension. Phosphorylated lamin-A,C localizes to nucleoplasm, and phosphorylation is enriched on lamin-A,C fragments and is suppressed by a cyclin-dependent kinase (CDK) inhibitor. Lamin-A,C knockdown in primary MSCs suppresses transcripts predominantly among actomyosin genes, especially in the serum response factor (SRF) pathway. Levels of myosin-IIA thus parallel levels of lamin-A,C, with phosphosite mutants revealing a key role for phosphoregulation. In modeling the system as a parsimonious gene circuit, we show that tension-dependent stabilization of lamin-A,C and myosin-IIA can suitably couple nuclear and cell morphology downstream of matrix mechanics.
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Amnon
authors.initials: A
authors.lastname: Buxboim
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Swift
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Jerome
authors.initials: J
authors.lastname: Irianto
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Kyle R
authors.initials: KR
authors.lastname: Spinler
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: P C Dave P
authors.initials: PC
authors.lastname: Dingal
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Avathamsa
authors.initials: A
authors.lastname: Athirasala
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Yun-Ruei C
authors.initials: YR
authors.lastname: Kao
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Sangkyun
authors.initials: S
authors.lastname: Cho
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Takamasa
authors.initials: T
authors.lastname: Harada
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Shin
authors.affiliation: Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: discher@seas.upenn.edu.
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Discher
mesh_terms: D002454:Cell Differentiation; D004548:Elasticity; D005109:Extracellular Matrix / Q000378:metabolism*; D025461:Feedback, Physiological; D006801:Humans; D034904:Lamin Type A / Q000235:genetics* / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D024507:Nonmuscle Myosin Type IIA / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D059010:Single-Cell Analysis
chemical_list: D034904:Lamin Type A; D024507:Nonmuscle Myosin Type IIA