Apicomplexan F-actin is required for efficient nuclear entry during host cell invasion

Area of Science:

• Cell biology
• Parasitology
• Molecular biology

Background:

• Apicomplexan parasites like Toxoplasma gondii and Plasmodium spp. are obligate intracellular pathogens.
• Host cell invasion is crucial for parasite survival and disease pathogenesis.
• Parasite entry involves forming a moving junction between parasite and host cell.

Purpose of the Study:

• To investigate the role and dynamics of F-actin during host cell invasion by apicomplexan parasites.
• To understand how F-actin contributes to the passage of the parasite nucleus through the host cell membrane.

Main Methods:

• Super-resolution microscopy
• Real-time live-cell imaging
• Analysis of F-actin distribution and dynamics
• Use of mutant parasites with dysfunctional acto-myosin

Main Results:

• F-actin was identified at the parasite apex, forming a ring at the junction, and in perinuclear and posterior regions.
• Mutant parasites lacking functional acto-myosin showed reduced F-actin at the junction and perinuclear regions.
• Nuclear passage through the host cell junction was impaired in these mutant parasites.

Conclusions:

• F-actin plays a dual role in host cell invasion by apicomplexan parasites.
• The F-actin machinery stabilizes the moving junction and facilitates nuclear translocation.
• This study provides the first evidence for actin-driven forces aiding nuclear passage during invasion.