Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, SC, 29425, USA.
Department of Surgery, Medical University of South Carolina, Charleston, SC, 29425, USA.
Angiogenesis. 2017 Nov;20(4):615-628. doi: 10.1007/s10456-017-9574-5. Epub 2017 Aug 24.
Secreted frizzled-related protein 2 (SFRP2) is a pro-angiogenic factor expressed in the vasculature of a wide variety of human tumors, and modulates angiogenesis via the calcineurin-dependent nuclear factor of activated T-cells cytoplasmic 3 (NFATc3) pathway in endothelial cells. However, until now, SFRP2 receptor for this pathway was unknown. In the present study, we first used amino acid alignments and molecular modeling to demonstrate that SFRP2 interaction with frizzled-5 (FZD5) is typical of Wnt/FZD family members. To confirm this interaction, we performed co-immunofluorescence, co-immunoprecipitation, and ELISA binding assays, which demonstrated SFRP2/FZD5 binding. Functional knock-down studies further revealed that FZD5 is necessary for SFRP2-induced tube formation and intracellular calcium flux in endothelial cells. Using protein analysis on endothelial cell nuclear extracts, we also discovered that FZD5 is required for SFRP2-induced activation of NFATc3. Our novel findings reveal that FZD5 is a receptor for SFRP2 and mediates SFRP2-induced angiogenesis via calcineurin/NFATc3 pathway in endothelial cells.
分泌型卷曲相关蛋白 2（SFRP2）是一种在多种人类肿瘤血管中表达的促血管生成因子，通过内皮细胞中钙调神经磷酸酶依赖性活化 T 细胞核因子细胞质 3（NFATc3）通路调节血管生成。然而，到目前为止，这种途径的 SFRP2 受体尚不清楚。在本研究中，我们首先通过氨基酸序列比对和分子建模证明，SFRP2 与卷曲蛋白 5（FZD5）的相互作用是典型的 Wnt/FZD 家族成员。为了证实这种相互作用，我们进行了共免疫荧光、共免疫沉淀和 ELISA 结合实验，结果表明 SFRP2/FZD5 结合。功能敲低研究进一步表明，FZD5 是 SFRP2 诱导内皮细胞管形成和细胞内钙流所必需的。通过对内皮细胞核提取物的蛋白分析，我们还发现 FZD5 是 SFRP2 诱导 NFATc3 激活所必需的。我们的新发现表明，FZD5 是 SFRP2 的受体，通过内皮细胞中的钙调神经磷酸酶/NFATc3 通路介导 SFRP2 诱导的血管生成。
