Membrane tether formation from blebbing cells

Jianwu Dai, Michael Sheetz

Research output: Contribution to journalArticle

295 Citations (Scopus)

Abstract

Membrane tension has been proposed to be important in regulating cell functions such as endocytosis and cell motility. The apparent membrane tension has been calculated from tether forces measured with laser tweezers. Both membrane-cytoskeleton adhesion and membrane tension contribute to the tether force. Separation of the plasma membrane from the cytoskeleton occurs in membrane blebs, which could remove the membrane-cytoskeleton adhesion term. In renal epithelial cells, tether forces are significantly lower on blebs than on membranes that are supported by cytoskeleton. Furthermore, the tether forces are equal on apical and basolateral blebs. In contrast, tether forces from membranes supported by the cytoskeleton are greater in apical than in basolateral regions, which is consistent with the greater apparent cytoskeletal density in the apical region. We suggest that the tether force on blebs primarily contains only the membrane tension term and that the membrane tension may be uniform over the cell surface. Additional support for this hypothesis comes from observations of melanoma cells that spontaneously bleb. In melanoma cells, tether forces on blebs are proportional to the radius of the bleb, and as large blebs form, there are spikes in the tether force in other cell regions. We suggest that an internal osmotic pressure inflates the blebs, and the pressure calculated from the Law of Laplace is similar to independent measurements of intracellular pressures. When the membrane tension term is subtracted from the apparent membrane tension over the cytoskeleton, the membrane-cytoskeleton adhesion term can be estimated. In both cell systems, membrane-cytoskeleton adhesion was the major factor in generating the tether force.

Original languageEnglish (US)
Pages (from-to)3363-3370
Number of pages8
JournalBiophysical Journal
Volume77
Issue number6
DOIs
StatePublished - Jan 1 1999
Externally publishedYes

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Blister
Cytoskeleton
Membranes
Melanoma
Cell Membrane
Optical Tweezers
Pressure
Osmotic Pressure
Endocytosis
Cell Movement
Epithelial Cells

ASJC Scopus subject areas

  • Biophysics

Cite this

Membrane tether formation from blebbing cells. / Dai, Jianwu; Sheetz, Michael.

In: Biophysical Journal, Vol. 77, No. 6, 01.01.1999, p. 3363-3370.

Research output: Contribution to journalArticle

Dai, Jianwu ; Sheetz, Michael. / Membrane tether formation from blebbing cells. In: Biophysical Journal. 1999 ; Vol. 77, No. 6. pp. 3363-3370.
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