Specific PKC isoforms regulate LPS-stimulated iNOS induction in murine microglial cells

Area of Science:

• Neuroscience
• Immunology
• Molecular Biology

Background:

• Reactive microglia contribute to neurological diseases via excessive nitric oxide (NO) production by inducible nitric oxide synthase (iNOS).
• Protein Kinase C (PKC) activation is linked to iNOS induction, but specific isoform roles remain unclear.
• Understanding specific PKC isoform involvement is crucial for developing targeted therapies.

Purpose of the Study:

• To elucidate the role of individual PKC isoforms in regulating iNOS expression in murine microglia.
• To identify the specific signaling pathways downstream of PKC involved in iNOS induction.

Main Methods:

• Utilized BV-2 murine microglia treated with specific PKC inhibitors and siRNA for isoform knockdown.
• Assessed iNOS expression and MAPK phosphorylation via Western blot.
• Investigated NF-κB activation using luciferase reporter assays.

Main Results:

• All tested PKC inhibitors reduced iNOS induction in lipopolysaccharide (LPS)-activated microglia.
• Knockdown of PKCδ and PKCβ significantly attenuated ERK1/2 and p38 phosphorylation, respectively.
• PKCδ and PKCβ inhibition blocked NF-κB activation, thereby suppressing iNOS expression.

Conclusions:

• PKCδ and PKCβ are identified as the primary PKC isoforms regulating iNOS expression in reactive microglia.
• PKC-mediated signaling involves distinct MAPK phosphorylation and NF-κB activation.
• These findings support the development of selective PKC inhibitors for treating NO-related inflammatory and neurological disorders.