Protein targeting to exosomes/microvesicles by plasma membrane anchors

Area of Science:

• Cell biology
• Molecular biology
• Biochemistry

Background:

• Animal cells release extracellular vesicles (EMVs), including exosomes and microvesicles.
• Previous studies indicated N-terminal acylation tags can direct cytoplasmic proteins into EMVs.

Purpose of the Study:

• To investigate if various membrane anchors can target the oligomeric protein TyA-GFP into EMVs.
• To determine the efficiency of different plasma membrane anchors in mediating EMV budding.
• To explore if plasma membrane anchors can target other oligomeric proteins into EMVs.

Main Methods:

• Utilized TyA-GFP fusion proteins with different membrane anchors (myristoylation, PIP(2)-binding, PIP(3)-binding, prenylation/palmitoylation, CD43).
• Targeted proteins to plasma membrane, endosome, and Golgi membranes.
• Quantified EMV budding efficiency relative to control.

Main Results:

• Multiple plasma membrane anchors successfully targeted TyA-GFP to EMVs, with varying efficiencies.
• Myristoylation and PIP(2)-binding domains showed the highest budding efficiency.
• Targeting to endosome and Golgi membranes resulted in significantly lower or no EMV budding.
• Plasma membrane anchors also directed other oligomeric proteins into EMVs.

Conclusions:

• Plasma membrane anchors are capable of targeting highly oligomeric cytoplasmic proteins into EMVs.
• The efficiency of EMV targeting varies significantly among different membrane anchors.
• EMV biogenesis shares similarities with retroviral budding, particularly in anchor-mediated budding efficiency.