Clostridioides difficile TcdB induces expression of its receptor (CSPG4) through a noncanonical Hippo signaling...

Area of Science:

• Microbiology
• Cell Biology
• Molecular Biology

Background:

• Chondroitin sulfate proteoglycan 4 (CSPG4) acts as a key receptor for Clostridioides difficile toxin B (TcdB).
• The regulation and expression dynamics of CSPG4 during C. difficile infection remain largely undescribed.

Purpose of the Study:

• To elucidate the molecular mechanisms by which TcdB influences CSPG4 expression.
• To investigate the roles of small GTPases and the Hippo signaling pathway in TcdB-mediated CSPG4 regulation.

Main Methods:

• Treatment of HeLa cells and human pericytes with TcdB and Rho inhibitors.
• Inhibition of Hippo kinases (MST1/2, LATS1/2) and analysis of downstream effectors.
• RNA-sequencing (RNA-seq) and CUT&RUN assays to assess gene expression and protein-DNA interactions.
• Investigated the role of CCCTC-binding factor (CTCF) in CSPG4 regulation.

Main Results:

• TcdB treatment and Rho inhibition significantly increased CSPG4 expression.
• Hippo kinase inhibition blocked TcdB-induced CSPG4 upregulation, independent of YAP/TAZ.
• RNA-seq and CUT&RUN revealed that CCCTC-binding factor (CTCF) represses CSPG4 expression.
• TcdB disrupted CTCF binding at the CSPG4 gene locus, leading to increased CSPG4 expression.

Conclusions:

• TcdB upregulates CSPG4 expression through Rho inactivation and subsequent Hippo-mediated inhibition of the transcriptional repressor CTCF.
• This mechanism highlights a novel pathway involving CTCF in the host response to C. difficile infection.