Profilin2 is required for filamentous actin formation induced by human parainfluenza virus type 2

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Human parainfluenza virus type 2 (hPIV-2) activates RhoA signaling, leading to filamentous actin (F-actin) formation.
• Actin-binding proteins like profilin and cofilin regulate F-actin dynamics downstream of RhoA signaling.

Purpose of the Study:

• To identify key molecules involved in hPIV-2-induced F-actin formation.
• To elucidate the mechanism by which hPIV-2 manipulates actin cytoskeleton dynamics.

Main Methods:

• Immunoprecipitation assays to detect protein-protein interactions.
• Western blotting to analyze protein levels and interactions.
• siRNA-mediated depletion to assess the functional role of profilin2.
• Site-directed mutagenesis to investigate the role of specific V protein residues.

Main Results:

• Profilin2 was identified as a key molecule in hPIV-2-induced F-actin formation.
• The hPIV-2 V protein specifically binds to profilin2, not profilin1.
• Trp residues in the C-terminus of the V protein are essential for profilin2 binding.
• Depletion of profilin2 inhibited hPIV-2-induced F-actin formation and suppressed viral growth.
• Wild-type V protein, but not the Trp-mutated version, reduced actin co-immunoprecipitated with profilin2.

Conclusions:

• hPIV-2 V protein directly interacts with profilin2.
• This interaction modulates the actin-profilin2 complex, promoting F-actin formation.
• The V protein-profilin2 interaction is critical for hPIV-2-induced cytoskeletal rearrangements and viral replication.