Mena-GRASP65 interaction couples actin polymerization to Golgi ribbon linking

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The Golgi reassembly stacking protein 65 (GRASP65) is crucial for Golgi stacking and ribbon linking.
• The mechanism by which GRASP65 bridges large, heterogeneous gaps between Golgi stacks remains unclear.

Purpose of the Study:

• To investigate the proteins that assist GRASP65 in linking Golgi stacks into ribbons.
• To identify novel GRASP65-binding proteins involved in Golgi ribbon formation.

Main Methods:

• Biochemical methods were employed to identify GRASP65-binding proteins.
• Cellular assays involved protein depletion and disruption of actin polymerization.
• In vitro experiments assessed the effects of Mena and microfilaments on GRASP65 oligomerization and membrane fusion.

Main Results:

• The actin elongation factor Mena was identified as a novel GRASP65-binding protein.
• Mena is recruited to Golgi membranes via GRASP65 interaction.
• Depletion of Mena or disruption of actin polymerization led to Golgi fragmentation.
• Mena and actin are required for Golgi ribbon formation in cells.
• Mena and microfilaments enhance GRASP65 oligomerization and Golgi membrane fusion in vitro.

Conclusions:

• Mena interacts with GRASP65 to facilitate Golgi ribbon linking.
• The study reveals a novel role for Mena and actin polymerization in maintaining Golgi ribbon structure.
• GRASP65-Mena interaction promotes local actin polymerization, essential for Golgi ribbon integrity.