Selective and uncoupled role of substrate elasticity in the regulation of replication and transcription in epithelial cells.
Actin cytoskeleton forms a physical connection between the extracellular matrix, adhesion complexes and nuclear architecture. Because tissue stiffness plays key roles in adhesion and cytoskeletal organization, an important open question concerns the influence of substrate elasticity on replication and transcription. To answer this major question, polyelectrolyte multilayer films were used as substrate models with apparent elastic moduli ranging from 0 to 500 kPa. The sequential relationship between Rac1, vinculin adhesion assembly, and replication becomes efficient at above 200 kPa because activation of Rac1 leads to vinculin assembly, actin fiber formation and, subsequently, to initiation of replication. An optimal window of elasticity (200 kPa) is required for activation of focal adhesion kinase through auto-phosphorylation of tyrosine 397. Transcription, including nuclear recruitment of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), occurred above 50 kPa. Actin fiber and focal adhesion signaling are not required for transcription. Above 50 kPa, transcription was correlated with alphav-integrin engagement together with histone H3 hyperacetylation and chromatin decondensation, allowing little cell spreading. By contrast, soft substrate (below 50 kPa) promoted morphological changes characteristic of apoptosis, including cell rounding, nucleus condensation, loss of focal adhesions and exposure of phosphatidylserine at the outer cell surface. On the basis of our data, we propose a selective and uncoupled contribution from the substrate elasticity to the regulation of replication and transcription activities for an epithelial cell model.
Kocgozlu
Leyla
L
Institut National de la Santé et de la Recherche Médicale, INSERM Unité 977, 67085 Strasbourg Cedex, France.
Lavalle
Philippe
P
Koenig
Géraldine
G
Senger
Bernard
B
Haikel
Youssef
Y
Schaaf
Pierre
P
Voegel
Jean-Claude
JC
Tenenbaum
Henri
H
Vautier
Dominique
D
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D049109:Cell Proliferation; D042002:Chromatin Assembly and Disassembly; D004548:Elasticity; D004847:Epithelial Cells / Q000473:pathology / Q000502:physiology*; D022001:Focal Adhesions / Q000737:chemistry / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D039001:Integrin alpha Chains / Q000378:metabolism; D009040:Motion Pictures / Q000706:statistics & numerical data; D051381:Rats; D015533:Transcriptional Activation; D016596:Vinculin / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
D000199:Actins; D006657:Histones; D039001:Integrin alpha Chains; D016596:Vinculin; D020830:rac1 GTP-Binding Protein