MEK/ERK pathway mediates PKC activation-induced recruitment of PKCζ and MMP-9 to podosomes

Area of Science:

• Cell Biology
• Molecular Biology

Background:

• Podosomes are crucial cellular structures for extracellular matrix invasion and degradation.
• Protein kinase C (PKC) activation by phorbol 12,13-dibutyrate (PDBu) induces podosome formation in normal human bronchial epithelial (NHBE) cells.
• Atypical PKCζ plays a role in regulating matrix metalloproteinase-9 (MMP-9) recruitment to podosomes.

Purpose of the Study:

• To investigate the signaling pathways involved in PKC activation-induced podosome formation and matrix degradation.
• To elucidate the role of specific kinases in PDBu-induced cellular processes.

Main Methods:

• Utilized PDBu to stimulate podosome formation in NHBE cells.
• Employed specific inhibitors for PI3K, Akt, Src, MEK/ERK, and JNK pathways.
• Assessed podosome formation, matrix degradation, and protein phosphorylation levels.
• Investigated the effect of PKCζ inhibition on downstream signaling.

Main Results:

• PDBu treatment increased phosphorylation of PI3K p85, Akt, Src, ERK1/2, and JNK.
• Inhibitors of PI3K, Akt, and Src blocked podosome formation and matrix degradation.
• MEK/ERK and JNK blockers reduced podosome proteolytic activity but not formation.
• PKCζ inhibition affected MEK/ERK and JNK phosphorylation and MMP-9 recruitment.

Conclusions:

• PKCζ activation is a key regulator of PDBu-induced podosome formation and matrix degradation.
• The PI3K/Akt/Src pathway is essential for podosome formation.
• The MEK/ERK and JNK pathways modulate the proteolytic activity of podosomes, potentially via PKCζ and MMP-9 recruitment.