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Myosin-1a powers the sliding of apical membrane along microvillar actin bundles

Russell E McConnell1, Matthew J Tyska

  • 1Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.

The Journal of Cell Biology
|May 16, 2007
PubMed

Insights

Myosin-1a (Myo1a) drives the movement of apical membrane along microvilli in the enterocyte brush border. This novel motility results in the shedding of membrane vesicles into the intestinal lumen.

Area of Science:

  • Cell Biology
  • Biophysics
  • Epithelial Biology

Background:

  • Microvilli are actin-rich protrusions in epithelial cells.
  • Myosin-1a (Myo1a) is localized to the brush border (BB) microvilli, forming bridges between the plasma membrane and actin bundles.
  • The precise function of the microvillar actomyosin array has been elusive.

Purpose of the Study:

  • To elucidate the function of myosin-1a (Myo1a) within the microvilli of the enterocyte brush border (BB).
  • To investigate the mechanism of apical membrane dynamics and vesicle release in microvilli.

Main Methods:

  • Isolated brush borders (BBs) were utilized to study membrane dynamics.
  • The effect of ATP addition on isolated BBs was observed.
  • Experiments were conducted with and without myosin-1a (Myo1a) to assess its role.

Main Results:

  • ATP addition induced a plus end-directed translation of apical membrane along microvillar actin bundles.
  • Membrane was observed to be shed from microvillar tips as vesicles.
  • Brush borders lacking Myo1a did not exhibit this membrane translation, confirming Myo1a's role.

Conclusions:

  • Myosin-1a (Myo1a) powers a novel form of motility involving apical membrane translation and vesicle shedding.
  • Microvilli act as actomyosin contractile arrays, facilitating vesicle release into the intestinal lumen.
  • This process contributes to amplifying apical surface area and nutrient absorption.

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