TY - JOUR
T1 - Cell protrusions and tethers
T2 - A unified approach
AU - Pospieszalska, Maria K.
AU - Lasiecka, Irena
AU - Ley, Klaus
N1 - Funding Information:
This work was supported by National Institutes of Health grant No. 2R01EB002185.
PY - 2011/4/6
Y1 - 2011/4/6
N2 - Low pulling forces applied locally to cell surface membranes produce viscoelastic cell surface protrusions. As the force increases, the membrane can locally separate from the cytoskeleton and a tether forms. Tethers can grow to great lengths exceeding the cell diameter. The protrusion-to-tether transition is known as the crossover. Here we propose a unified approach to protrusions and tethers providing, to our knowledge, new insights into their biomechanics. We derive a necessary and sufficient condition for a crossover to occur, a formula for predicting the crossover time, conditions for a tether to establish a dynamic equilibrium (characterized by constant nonzero pulling force and tether extension rate), a general formula for the tether material after crossover, and a general modeling method for tether pulling experiments. We introduce two general protrusion parameters, the spring constant and effective viscosity, valid before and after crossover. Their first estimates for neutrophils are 50 pNμm-1 and 9 pN s μm-1, respectively. The tether elongation after crossover is described as elongation of a viscoelasticlike material with a nonlinearly decaying spring (NLDs-viscoelastic material). Our model correctly describes the results of the published protrusion and tether pulling experiments, suggesting that it is universally applicable to such experiments.
AB - Low pulling forces applied locally to cell surface membranes produce viscoelastic cell surface protrusions. As the force increases, the membrane can locally separate from the cytoskeleton and a tether forms. Tethers can grow to great lengths exceeding the cell diameter. The protrusion-to-tether transition is known as the crossover. Here we propose a unified approach to protrusions and tethers providing, to our knowledge, new insights into their biomechanics. We derive a necessary and sufficient condition for a crossover to occur, a formula for predicting the crossover time, conditions for a tether to establish a dynamic equilibrium (characterized by constant nonzero pulling force and tether extension rate), a general formula for the tether material after crossover, and a general modeling method for tether pulling experiments. We introduce two general protrusion parameters, the spring constant and effective viscosity, valid before and after crossover. Their first estimates for neutrophils are 50 pNμm-1 and 9 pN s μm-1, respectively. The tether elongation after crossover is described as elongation of a viscoelasticlike material with a nonlinearly decaying spring (NLDs-viscoelastic material). Our model correctly describes the results of the published protrusion and tether pulling experiments, suggesting that it is universally applicable to such experiments.
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U2 - 10.1016/j.bpj.2011.02.038
DO - 10.1016/j.bpj.2011.02.038
M3 - Article
AN - SCOPUS:79955412757
SN - 0006-3495
VL - 100
SP - 1697
EP - 1707
JO - Biophysical Journal
JF - Biophysical Journal
IS - 7
ER -