Porphyromonas gingivalis SerB-mediated dephosphorylation of host cell cofilin modulates invasion efficiency

Area of Science:

• Microbiology
• Cell Biology
• Pathogenesis

Background:

• Porphyromonas gingivalis is an opportunistic pathogen linked to virulence and host cell invasion.
• The serine phosphatase SerB from P. gingivalis is implicated in host cell interactions, including actin rearrangement, but its precise mechanism is unclear.
• Cofilin, an actin-depolymerizing protein, plays a role in cellular processes affected by bacterial pathogens.

Purpose of the Study:

• To investigate the effect of P. gingivalis SerB on the host protein cofilin.
• To elucidate the role of cofilin in P. gingivalis invasion of gingival epithelial cells.

Main Methods:

• Studied the dephosphorylation of cofilin in gingival epithelial cells following P. gingivalis infection.
• Utilized a SerB-deficient P. gingivalis mutant to assess SerB's role in cofilin dephosphorylation.
• Employed quantitative image analysis of epithelial cells with altered cofilin levels (knockdown/knock-in) to determine cofilin's involvement in bacterial invasion.
• Investigated the interplay between SerB, cofilin, and LIM kinase in P. gingivalis invasion.

Main Results:

• P. gingivalis infection led to cofilin dephosphorylation, an effect dependent on SerB.
• Silencing cofilin significantly reduced intracellular P. gingivalis.
• Expression of active cofilin enhanced bacterial invasion, while inactive cofilin inhibited it.
• LIM kinase reduced invasion, but this was reversed by active cofilin.

Conclusions:

• P. gingivalis SerB directly induces cofilin dephosphorylation.
• Active cofilin is a critical host factor required for efficient invasion of gingival epithelial cells by P. gingivalis.
• This highlights a novel mechanism by which P. gingivalis manipulates host cell actin dynamics for invasion.