Protein Kinase C-delta (PKCδ) is endogenously expressed by vascular SMCs36 and becomes
upregulated in injured arteries and aneurysmal tissues.10, 37 We have previously demonstrated that PKCδ
plays an important role in SMC apoptosis38 and chemokine expression.31 Prkcd-/- mice are resistant to
aneurysm inductions in both calcium chloride induced- and elastase-induced mouse models of AAA.10
Interestingly, co-immunostaining revealed that the RIP3 and PKCδ are co-expressed in the SMC-rich
medial layer of mouse aneurysmal tissues (Figure 6A). To delineate functional interactions between RIP3
and PKCδ, we subjected aortic SMCs isolated from Prkcd-/- mice and their WT littermates to necroptosis
induction with TNα/zVAD. Prkcd+/+ SMCs responded to the TNα/zVAD treatment with necrosis that was
inhibited by necrostatin-1. However, Prkcd-/- SMCs failed to undergo necrostatin-1 sensitive-necroptosis
(Figure 6B). Similar necroptosis resistances in both primary cultured aortic SMCs from C57BL/6 mice and
MOVAS cells (a mouse aortic SMC line) were also produced by siRNA-mediated transient knockdown of
Prkcd (Figure 6C; Online Figure VII B and XI A). Restoration of PKCδ expression with a PKCδ-expressing
adenovirus (AdPKCδ) rescued sensitivity to necroptosis induction (Figure 6D). Notably, knocking down
Prkcd in L929, a murine aneuploid fibrosarcoma cell line widely used in necroptosis studies39, did not
protect cells from necroptosis (Supplemental Figure XI B), indicating that the involvement of PKCδ in
necroptosis might be cell-type specific