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Targeting of a tropomyosin isoform to short microfilaments associated with the Golgi complex

Justin M Percival1, Julie A I Hughes, Darren L Brown

  • 1Oncology Research Unit, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia.

Molecular Biology of the Cell
|October 7, 2003
PubMed

Insights

Tropomyosin Tm5NM-2 specifically localizes to the Golgi complex, associating with short actin filaments on vesicles. This suggests a role for Golgi-associated actin in vesicle budding.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cytoskeleton Dynamics

Background:

  • The Golgi complex is known to interact with an actin-based filament system.
  • Previous research identified tropomyosin Tm5NM (gamma-Tm) isoforms associated with Golgi-derived vesicles.

Purpose of the Study:

  • To investigate the specific localization and function of tropomyosin Tm5NM isoforms within the Golgi complex.
  • To elucidate the role of actin filaments in Golgi-derived vesicle trafficking.

Main Methods:

  • Immunofluorescence microscopy to visualize Tm5NM isoforms and actin filaments.
  • Cell cycle analysis of Tm5NM-2 localization.
  • Treatment with brefeldin A and cytochalasin D to assess drug sensitivity.
  • Antibody labeling targeting actin filament ends.

Main Results:

  • Tm5NM-2 is specifically sorted to the Golgi complex, while Tm5NM-1 localizes to stress fibers.
  • Tm5NM-2 associates with Golgi membranes in a brefeldin A-sensitive, cytochalasin D-resistant manner.
  • Short actin filaments are newly identified at the Golgi and on associated vesicles, with Tm5NM-2 localized to these structures.

Conclusions:

  • Alternative splicing of the tropomyosin gene Tm5NM dictates isoform localization to either the Golgi complex or stress fibers.
  • Golgi-associated actin microfilaments, decorated by Tm5NM-2, are implicated in vesicle budding from the Golgi complex.

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