Surrozen Inc., 171 Oyster Point Blvd, Suite 400, South San Francisco, CA, 94080, USA.
Sci Rep. 2020 Aug 18;10(1):13951. doi: 10.1038/s41598-020-70912-3.
R-spondin (RSPO) proteins amplify Wnt signaling and stimulate regeneration in a variety of tissues. To repair tissue in a tissue-specific manner, tissue-targeted RSPO mimetic molecules are desired. Here, we mutated RSPO (RSPO2 F105R/F109A) to eliminate LGR binding while preserving ZNRF3/RNF43 binding and targeted the mutated RSPO to a liver specific receptor, ASGR1. The resulting bi-specific molecule (αASGR1-RSPO2-RA) enhanced Wnt signaling effectively in vitro, and its activity was limited to ASGR1 expressing cells. Systemic administration of αASGR1-RSPO2-RA in mice specifically upregulated Wnt target genes and stimulated cell proliferation in liver but not intestine (which is more responsive to non-targeted RSPO2) in healthy mice, and improved liver function in diseased mice. These results not only suggest that a tissue-specific RSPO mimetic protein can stimulate regeneration in a cell-specific manner, but also provide a blueprint of how a tissue-specific molecule might be constructed for applications in a broader context.
RSPO 蛋白可放大 Wnt 信号通路并刺激多种组织的再生。为了以组织特异性的方式修复组织，需要组织靶向的 RSPO 模拟分子。在这里，我们对 RSPO（RSPO2 F105R/F109A）进行了突变，以消除 LGR 结合，同时保留 ZNRF3/RNF43 结合，并将突变后的 RSPO 靶向肝脏特异性受体 ASGR1。由此产生的双特异性分子（αASGR1-RSPO2-RA）在体外有效增强了 Wnt 信号通路，其活性仅限于表达 ASGR1 的细胞。在健康小鼠中，系统给予 αASGR1-RSPO2-RA 可特异性地上调 Wnt 靶基因并刺激肝脏细胞增殖（对非靶向 RSPO2 的反应更为敏感），而不会刺激肠道细胞增殖（这对非靶向 RSPO2 的反应更为敏感），并改善了患病小鼠的肝功能。这些结果不仅表明组织特异性 RSPO 模拟蛋白可以以细胞特异性的方式刺激再生，还为如何构建组织特异性分子提供了蓝图，以便在更广泛的背景下应用。
