Quantitative Proteomics Reveals the Dynamics of Protein Phosphorylation in Human Bronchial Epithelial Cells during Internalization, Phagosomal Escape, and Intracellular Replication of <i>Staphylococcus aureus</i>

Internalization
of Staphylococcus aureus by nonprofessional
phagocytic cells is a major suspected cause of persistent and difficult-to-treat
infections, including pneumonia. In this study, we established an
infection model with 16HBE14o- human bronchial epithelial cells and
demonstrated internalization, escape from phagosomal clearance, and
intracellular replication of S. aureus HG001 within
the first 4 h postinfection. We used quantitative phosphoproteomics
to identify characteristic signaling networks in the host at different
infection stages. Although we found only minor changes in protein
abundance, the infection was accompanied by highly dynamic alterations
in phosphorylation events primarily in proteins that are associated
with pathways of cytoskeleton dynamics, cell–cell and cell–matrix
contacts, vesicle trafficking, autophagy, and GTPase signaling. Analyses
of host protein kinases by kinase-substrate mapping, active regulatory
site immunoblotting, and prediction algorithms highlighted known and
novel host kinases with putative critical roles in S. aureus infection-accompanied signaling including FAK, PKA, PKC, and CDK.
Targeted pharmacological inhibition of these kinases resulted in a
significant reduction of intracellular S. aureus cells.
The current study constitutes a valuable resource for better understanding
the infection-relevant molecular pathomechanisms of airway cells and
for developing novel host-centric anti-infective strategies for treating S. aureus infections.