The hydrogel nature of mammalian cytoplasm contributes to osmosensing and extracellular pH sensing.

Fels J, Orlov SN, Grygorczyk R

Forschungsartikel (Zeitschrift) | Peer reviewed

Zusammenfassung

Cytoplasm is thought to have many hydrogel-like characteristics, including the ability to absorb large amounts of water and change volume in response to alterations in external environment, as well as having limited leakage of ions and proteins. Some gel-like behaviors have not been rigorously confirmed in mammalian cells, and others should be examined under conditions where gel volume can be accurately monitored. Thus, possible contributions of cytoplasm hydrogel properties to cellular processes such as volume sensing and regulation remain unclear. We used three-dimensional imaging to measure volume of single substrate-attached cells after permeabilization of their plasma membrane. Permeabilized cells swelled or shrinked reversibly in response to variations of external osmolality. Volume changes were 3.7-fold greater than observed with intact cells, consistent with cytoplasm's high water-absorbing capacity. Volume was maximal at neutral pH and shrunk at acidic or alkaline pH, consistent with pH-dependent changes of protein charge density and repulsive forces within cellular matrix. Volume shrunk with increased Mg(2+) concentration, as expected for increased charge screening and ionic crosslinking effects. Findings demonstrate that mammalian cytoplasm resembles hydrogel and functions as a highly sensitive osmosensor and extracellular pH sensor. Its high water-absorbing capacity may allow rapid modulation of local fluidity, macromolecular crowding, and activity of intracellular environment.

Details zur Publikation

FachzeitschriftBiophysical Journal (Biophys J.)
Jahrgang / Bandnr. / Volume96
Ausgabe / Heftnr. / Issue10
Seitenbereich4276-4285
StatusVeröffentlicht
Veröffentlichungsjahr2009
Sprache, in der die Publikation verfasst istEnglisch
DOI10.1016/j.bpj.2009.02.038
StichwörterExtracellular Space; Osmolar Concentration; Cell Membrane; Humans; Hydrogen-Ion Concentration; Permeability; Cell Line Tumor; Hydrogels; Animals; Cell Size; Magnesium Chloride; Cytoplasm; Extracellular Space; Osmolar Concentration; Cell Membrane; Humans; Hydrogen-Ion Concentration; Permeability; Cell Line Tumor; Hydrogels; Animals; Cell Size; Magnesium Chloride; Cytoplasm

Autor*innen der Universität Münster

Fels, Johannes
Institut für Physiologie II