Actin-based features negatively regulated by protein kinase C-epsilon

Area of Science:

• Cell Biology
• Biochemistry

Background:

• Phorbol 12-myristate 13-acetate (PMA) induces morphological changes in cells, including actin cytoskeleton remodeling, which are also observed during oncogenic transformation.
• PMA activates protein kinase C (PKC), and subsequent enzyme degradation may influence actin remodeling.

Purpose of the Study:

• To investigate the role of protein kinase C (PKC) isozyme degradation in PMA-induced actin cytoskeleton remodeling.
• To determine if PKC-epsilon degradation correlates with stress fiber formation and to elucidate its regulatory function.

Main Methods:

• Quantified PKC isozyme levels in tracheal epithelial cells after PMA exposure.
• Utilized RNA interference and antisense oligodeoxynucleotide to knock down PKC-epsilon expression.
• Measured stress fiber accumulation and PKC-epsilon content via real-time PCR and protein level analysis.

Main Results:

• PKC-epsilon was the only PKC isozyme to show degradation correlated with increased stress fiber accumulation.
• Stress fibers increased significantly between 5 and 10 hours post-PMA exposure as PKC-epsilon levels declined.
• PKC-epsilon knockdown enhanced stress fiber formation, both in untreated cells and after PMA exposure.

Conclusions:

• PKC-epsilon negatively regulates the formation of stress fibers.
• PKC-epsilon may control stress fiber organization by directly affecting their components or upstream regulatory pathways.