CD44-independent activation of the Met signaling pathway by HGF and InlB

Area of Science:

• Microbiology
• Cell Biology
• Immunology

Background:

• Listeria monocytogenes is a pathogen causing listeriosis.
• The surface protein InlB facilitates bacterial entry into host cells by interacting with the c-Met receptor.
• CD44, a hyaluronic acid receptor, and its CD44v6 isoform were hypothesized to be crucial for c-Met activation during L. monocytogenes invasion.

Purpose of the Study:

• To investigate the role of CD44 and its CD44v6 isoform in Listeria monocytogenes internalization into non-phagocytic cells.
• To determine if CD44 is involved in the activation of the c-Met signaling pathway by L. monocytogenes InlB or hepatocyte growth factor (HGF).

Main Methods:

• Utilized cell lines to study bacterial internalization.
• Employed siRNA to deplete CD44 and CD44v6 expression.
• Assessed c-Met activation and CD44 isoform recruitment at the bacterial entry site.
• Investigated the effect of CD44 and CD44v6 overexpression on bacterial internalization.

Main Results:

• CD44 receptors did not play a role in c-Met activation during L. monocytogenes entry or HGF stimulation.
• No CD44 isoforms were recruited to the site of L. monocytogenes entry.
• Depletion of CD44 or CD44v6 did not reduce bacterial infections.
• Overexpression of CD44 or CD44v6 had no significant impact on L. monocytogenes internalization.

Conclusions:

• The activation of the c-Met receptor by L. monocytogenes or HGF is largely independent of CD44.
• CD44 and its CD44v6 isoform are not essential for L. monocytogenes internalization into the tested non-phagocytic cells.