Visiting Instructor/Lecturer, Pediatrics - Critical Care
deltaPKC-Mediated Drp1 Phosphorylation Impacts Macrophage Mitochondrial Function and Inflammatory Response to Endotoxin.
Shock (Augusta, Ga.)
BACKGROUND: Recent studies have demonstrated that alterations in mitochondrial dynamics can impact innate immune function. However, the upstream mechanisms which link mitochondrial dynamics to innate immune phenotypes have not been completely elucidated. This study asks if deltaPKC-mediated phosphorylation of Drp1, a key driver of mitochondrial fission, impacts macrophage pro-inflammatory response following bacterial-derived lipopolysaccharide (LPS) stimulation.METHODS: Using RAW 264.7 cells, bone marrow-derived macrophages from C57BL/6J mice, as well as human monocyte-derived macrophages, we first characterized changes in deltaPKC-mediated phosphorylation of Drp1 following LPS stimulation. Next, using rationally-designed peptides that inhibit deltaPKC activation (deltaV1-1) and deltaPKC-Drp1 interaction (psiDrp1), we determined whether deltaPKC-mediated phosphorylation of Drp1 impacts LPS-induced changes in mitochondrial morphology, mitochondrial function, and inflammatory response.RESULTS: Our results demonstrated that deltaPKC-dependent Drp1 activation is associated with increased mitochondrial fission, impaired cellular respiration, and increased mitochondrial reactive oxygen species in LPS-treated macrophages. This is reversed using a rationally-designed peptide which selectively inhibits deltaPKC phosphorylation of Drp1 (psiDrp1). Interestingly, limiting excessive mitochondrial fission using psiDrp1 reduced LPS-triggered pro-inflammatory response, including a decrease in NF-kappaB nuclear localization, decreased iNOS induction, and a reduction in pro-inflammatory cytokines (IL-1beta, TNFalpha, IL-6).CONCLUSION: These data suggest that inhibiting Drp1 phosphorylation by deltaPKC abates the excessive mitochondrial fragmentation and mitochondrial dysfunction that is seen following LPS treatment. Furthermore, these data suggest that limiting deltaPKC-dependent Drp1 activation decreases the pro-inflammatory response following LPS treatment. Altogether, deltaPKC-dependent Drp1 phosphorylation might be an upstream mechanistic link between alterations in mitochondrial dynamics and innate immune phenotypes, and may have therapeutic potential.
View details for DOI 10.1097/SHK.0000000000001885
View details for PubMedID 34738957