Myosin-Vb functions as a dynamic tether for peripheral endocytic compartments during transferrin trafficking

BMC Cell Biol. 2008 Aug 7;9:44. doi: 10.1186/1471-2121-9-44.

Abstract

Background: Myosin-Vb has been shown to be involved in the recycling of diverse proteins in multiple cell types. Studies on transferrin trafficking in HeLa cells using a dominant-negative myosin-Vb tail fragment suggested that myosin-Vb was required for recycling from perinuclear compartments to the plasma membrane. However, chemical-genetic, dominant-negative experiments, in which myosin-Vb was specifically induced to bind to actin, suggested that the initial hypothesis was incorrect both in its site and mode of myosin-Vb action. Instead, the chemical-genetic data suggested that myosin-Vb functions in the actin-rich periphery as a dynamic tether on peripheral endosomes, retarding transferrin transport to perinuclear compartments.

Results: In this study, we employed both approaches, with the addition of overexpression of full-length wild-type myosin-Vb and switching the order of myosin-Vb inhibition and transferrin loading, to distinguish between these hypotheses. Overexpression of full-length myosin-Vb produced large peripheral endosomes. Chemical-genetic inhibition of myosin-Vb after loading with transferrin did not prevent movement of transferrin from perinuclear compartments; however, virtually all myosin-Vb-decorated particles, including those moving on microtubules, were halted by the inhibition. Overexpression of the myosin-Vb tail caused a less-peripheral distribution of early endosome antigen-1 (EEA1).

Conclusion: All results favored the peripheral dynamic tethering hypothesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Cell Compartmentation
  • Endosomes / metabolism*
  • Fluorescent Antibody Technique
  • Green Fluorescent Proteins / metabolism
  • HeLa Cells
  • Humans
  • Myosin Type V / metabolism*
  • Transfection
  • Transferrin / metabolism*

Substances

  • Transferrin
  • Green Fluorescent Proteins
  • Myosin Type V