RHOA-mediated mechanical force generation through Dectin-1.

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Dectin-1 (CLEC7A) is an innate immune receptor recognizing beta-glucans on Candida albicans.
• Dectin-1 activation initiates phagocytosis, oxidative burst, and cytokine production.
• Specific downstream mechanisms coordinating Dectin-1-mediated phagocytosis remain incompletely understood.

Purpose of the Study:

• To elucidate the signaling pathways downstream of Dectin-1 that regulate actin reorganization and fungal internalization.
• To investigate the role of mechanical force generation in Dectin-1-triggered phagocytosis.
• To identify key molecular players, including kinases and GTPases, involved in this process.

Main Methods:

• Utilized Dectin-1-transfected HEK-293 cells and M1 macrophages stimulated with soluble beta-glucan.
• Employed inhibitor studies targeting spleen tyrosine kinase (SYK) and SRC family kinases (SFK).
• Assessed mechanical force generation, areal contraction, RHOA activation, stress fiber formation, and Candida albicans phagocytosis.

Main Results:

• Dectin-1 stimulation induced mechanical force generation and areal contraction.
• This process was SYK-independent but SFK-dependent, mediated by the RHOA-ROCK-myosin light chain (MLC) pathway.
• RHOA activation and stress fiber formation were confirmed downstream of Dectin-1.
• The RHOA-ROCK-MLC pathway was essential for efficient phagocytosis of Candida albicans.

Conclusions:

• Dectin-1 signaling activates SFK, leading to RHOA-ROCK-MLC-mediated force generation critical for phagocytosis.
• This pathway provides a mechanistic link between Dectin-1 recognition and the physical process of fungal internalization.
• Findings highlight the RHOA-ROCK-MLC axis as a key target for modulating Dectin-1-dependent immune responses.