When One Is Enough: The Only Gα Subunit Governs Encystation and Other Cellular Processes in Entamoeba invadens

Area of Science:

• Cell Biology
• Parasitology
• Molecular Biology

Background:

• G protein subunits (Gα, Gβ, Gγ) mediate signals from G-protein coupled receptors (GPCRs).
• Entamoeba, the agent of Amoebiasis, is suspected to possess a GPCR pathway involved in encystation, phagocytosis, and motility.
• A Gα subunit, EhGα1, is known to be involved in pathogenic processes in Entamoeba histolytica.

Purpose of the Study:

• To characterize the Gα subunit ortholog, EiGα1, in Entamoeba invadens.
• To investigate the role of EiGα1 in Entamoeba encystation, cell aggregation, actin polymerization, motility, and phagocytosis.

Main Methods:

• Trigger-mediated knockdown of EiGα1 in Entamoeba invadens.
• Analysis of encystation efficiency, cell aggregation, chitin wall formation, and F-actin polymerization.
• Assessment of cell polarity, motility, and bacterial phagocytosis.
• Examination of EiGα1's control over EiMAPK15 and EiHbox1 expression.

Main Results:

• EiGα1 is expressed in both trophozoites and during encystation.
• EiGα1 silencing reduced encystation efficiency, leading to improper cell aggregation and abnormal chitin wall formation.
• Downregulation of EiGα1 caused anomalous F-actin polymerization, loss of polarity, and reduced motility.
• EiGα1 knockdown decreased bacterial phagocytosis and affected the expression of EiMAPK15 and EiHbox1.

Conclusions:

• EiGα1 plays an essential role in Entamoeba stage conversion and actin cytoskeleton rearrangement.
• The study provides strong evidence for a GPCR signaling network in Entamoeba.
• EiGα1 controls cyst-wall development and actin reorganization through EiMAPK15 and EiHbox1.