Here, we report that VP1 binds to serine/threonine kinase 3 (STK3), a member of the mammalian STE20-like (MST) kinase family.
Additionally, the amino acid residues in FMDV VP1 that mediate the interaction with STK3 were identified.
The cDNA of porcine STK3 was amplified from PK-15 cells and cloned into the pcDNATM3.1/ myc-His(-)A vector (Invitrogen, Carlsbad, CA, USA) to yield the Myc-tagged expression construct (Myc-STK3).
STK3 that was recovered from the library matched porcine STK3 (National Center for Biotechnology Information [NCBI] reference sequence GACC01000309.1).
Knockdown of STK3 Using a Small Interfering RNA (siRNA).
The FMDV Structural Protein VP1 Interacts with the Porcine Host Protein STK3. To date, the multiple functions of FMDV VP1 during viral infection remain unclear.
To confirm the interaction of VP1 and STK3, HEK293T cells were cotransfected with a Myc-STK3 expressing plasmid and a FLAG-VP1 expressing plasmid or an empty FLAG vector.
To further confirm that the FMDV VP1 and STK3 interaction occurs in vivo, PK-15 cells were transfected with a FLAG-VP1 expressing plasmid or an empty FLAG vector.
An IFA was performed subsequently, and the results indicated an interaction between VP1 and STK3 (Figure 1(e)).
In cultured primary cortical neurons, 4-HNE increased the protein levels of phosphop53 and cell cycle-related proteins (cyclin D3, cyclin D1, and CDC25A), caspase-3 activation, PARP cleavage, calpain activation, serine/threonine kinase 3 (Stk3
), and sphingosine phosphate lyase 1 (Sgpl1) upregulation.
10 differentially expressed proteins (YWHAQ (14-3-3), YWHAH (14-3-3), ITGB2 (ITGB2), ACTB (F-actin), PPP2R2A (PP2A), STK3
(Mst1/2), PPP1CA (PP1), CSNK1E (CK1<$/e), NF2 (Mer), and PPP2R1A (PP2A)) were associated with Hippo signaling pathway (Figure 4).