Microtubules can bear enhanced compressive loads in living cells because of lateral reinforcement.
Cytoskeletal microtubules have been proposed to influence cell shape and mechanics based on their ability to resist large-scale compressive forces exerted by the surrounding contractile cytoskeleton. Consistent with this, cytoplasmic microtubules are often highly curved and appear buckled because of compressive loads. However, the results of in vitro studies suggest that microtubules should buckle at much larger length scales, withstanding only exceedingly small compressive forces. This discrepancy calls into question the structural role of microtubules, and highlights our lack of quantitative knowledge of the magnitude of the forces they experience and can withstand in living cells. We show that intracellular microtubules do bear large-scale compressive loads from a variety of physiological forces, but their buckling wavelength is reduced significantly because of mechanical coupling to the surrounding elastic cytoskeleton. We quantitatively explain this behavior, and show that this coupling dramatically increases the compressive forces that microtubules can sustain, suggesting they can make a more significant structural contribution to the mechanical behavior of the cell than previously thought possible.
Brangwynne
Clifford P
CP
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
MacKintosh
Frederick C
FC
Kumar
Sanjay
S
Geisse
Nicholas A
NA
Talbot
Jennifer
J
Mahadevan
L
L
Parker
Kevin K
KK
Ingber
Donald E
DE
Weitz
David A
DA
D000205:Actomyosin / Q000494:pharmacology; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D019245:Compressive Strength; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D000205:Actomyosin