Mouse anti-Human PKCθ monoclonal antibody, clone 38/QLDθ [APC]

Aims Uptake of oxidized lipoprotein particles (oxLDL) and foam cell formation by macrophages is one of the first steps in the development of atherosclerosis. Recently, protein kinase C delta (PKC delta) has been implicated as a regulator of oxLDL uptake and foam cell formation via down-regulation of PKC beta and scavenger receptors CD36 and SR-A expression. Here, we describe studies in which we have re-evaluated the role of PKC delta in oxLDL uptake and foam cell formation. Methods and results PKC delta expression was silenced in the human monocytic cell lines and also in primary human monocytes to analyse oxLDL uptake and CD36 expression. Additionally, bone marrow-derived macrophages of PKC delta knockout mice and macrophages cultured from patients with rare null mutations in the PRKCD gene were tested for uptake of oxLDL and foam cell formation. Expression of scavenger receptor CD36 was determined and levels of PKC beta isoforms were quantified. Neither a reduction in PKC delta levels nor its complete absence resulted in a detectable effect on the uptake of oxLDL and the formation of foam cells. Conclusion PKC delta is dispensible for oxLDL uptake and foam cell formation by monocytes and macrophages.

Background: PKC delta expressed in neutrophils is implicated in promoting reperfusion injury after ischemic stroke. To understand the molecular and cellular actions of PKC delta, we employed a chemical-genetics approach to identify PKCd substrates in neutrophils. Results: We recently generated knock-in mice endogenously expressing analog-specific PKC delta (AS-PKC delta) that can utilize ATP analogs as phosphate donors. Using neutrophils isolated from the knock-in mice, we identified several PKC delta substrates, one of which was lipocalin-2 (LCN2), which is an iron-binding protein that can trigger apoptosis by reducing intracellular iron concentrations. We found that PKC delta phosphorylated LCN2 at T115 and this phosphorylation was reduced in Prkcd(-/-) mice. PKC delta colocalized with LCN2 in resting and stimulated neutrophils. LCN2 release from neutrophils after cerebral ischemia was reduced in PKC delta null mice. Conclusions: These findings suggest that PKC delta phosphorylates LCN2 and mediates its release from neutrophils during ischemia-reperfusion injury.