Myosin IIA motor regulates attaching-effacing bacteria interactions with intestinal epithelium

Area of Science:

• Microbiology
• Cell Biology
• Immunology

Background:

• Attaching and effacing (A/E) bacteria colonize intestinal epithelial cells (IECs) by remodeling the host cell cytoskeleton.
• Non-muscle myosin II (NM II) is crucial for actin cytoskeleton regulation, but its role in A/E pathogen colonization is unknown.

Purpose of the Study:

• To investigate the role of NM II paralogs, NM IIA and NM IIC, in intestinal epithelial cell colonization by A/E pathogens.
• To determine how NM IIA and NM IIC influence bacterial attachment, actin pedestal formation, and host inflammatory responses.

Main Methods:

• Utilized mouse models with targeted genetic deletions of NM IIA and NM IIC in intestinal epithelial cells.
• Employed in vitro studies with IEC lines, including CRISPR-Cas9 gene editing for NM IIA and NM IIC.
• Administered pharmacological modulators of NM II activity, including blebbistatin and 4-hydroxyacetophenone (4-HAP).

Main Results:

• Intestinal epithelial-specific deletion of NM IIA (NM IIA cKO) and expression of NM IIA motor domain mutants led to increased Citrobacter rodentium colonization and exacerbated mucosal inflammation.
• Total deletion of NM IIC (NM IIC tKO) did not affect C. rodentium colonization.
• Pharmacological inhibition of NM II (blebbistatin) and genetic knockout of NM IIA increased enteropathogenic E. coli (EPEC) attachment to IECs, dependent on bacterial virulence factors.

Conclusions:

• NM IIA, but not NM IIC, plays a significant role in limiting intestinal epithelial colonization by A/E pathogens.
• NM IIA functions by inhibiting pathogen-induced actin cytoskeleton remodeling and actin pedestal assembly.
• These findings reveal a novel host defense mechanism involving NM IIA against enteric bacterial infections.