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journal contribution
posted on 2019-04-09, 16:06 authored by Marina S. Hernandes, Bernard Lassègue, Lula Hilenski, Jonathan Adams, Ning Gao, Chia-Yi Kuan, Yu-Yo Sun, Lihong Cheng, Daniel Kikuchi, Manuel Yepes, Kathy K. GriendlingPolymerase δ-interacting protein 2 (Poldip2) is a multifunctional protein that regulates vascular
extracellular matrix composition and matrix metalloproteinase (MMP) activity. The blood-brain barrier (BBB) is a
dynamic system assembled by endothelial cells, basal lamina, and perivascular astrocytes, raising the possibility
that Poldip2 may be involved in maintaining its structure. We investigated the role of Poldip2 in the late BBB
permeability induced by cerebral ischemia. Transient middle cerebral artery occlusion (tMCAO) was induced in Poldip2+/+ and Poldip2+/− mice.
The volume of the ischemic lesion was measured in triphenyltetrazolium chloride-stained sections. BBB breakdown was
evaluated by Evans blue dye extravasation. Poldip2 protein expression was evaluated by western blotting.
RT-PCR, zymography, and ELISAs were used to measure mRNA levels, activity, and protein levels of cytokines
and MMPs. Cultured astrocytes were transfected with Poldip2 siRNA, and mRNA levels of cytokines were
evaluated as well as IκBα protein degradation. Cerebral ischemia induced the expression of Poldip2. Compared to Poldip2+/+ mice, Poldip2+/− animals
exhibited decreased Evans blue dye extravasation and improved survival 24 h following stroke. Poldip2 expression was
upregulated in astrocytes exposed to oxygen and glucose deprivation (OGD) and siRNA-mediated downregulation of
Poldip2 abrogated OGD-induced IL-6 and TNF-α expression. In addition, siRNA against Poldip2 inhibited TNF-α-induced
IκBα degradation. TNF-α, IL-6, MCP-1, VEGF, and MMP expression induced by cerebral ischemia was abrogated in Poldip2
+/− mice. The protective effect of Poldip2 depletion on the increased permeability of the BBB was partially reversed by
systemic administration of TNF-α.
Conclusions: Poldip2 is upregulated following ischemic stroke and mediates the breakdown of the BBB by increasing
cerebral cytokine production and MMP activation. Therefore, Poldip2 appears to be a promising novel target for the
development of therapeutic strategies to prevent the development of cerebral edema in the ischemic brain.