Evolutionary Turnover in Wnt Gene Expression but Conservation of Wnt Signaling during Ovary Determination in a TSD Reptile
Evolutionary Turnover in Wnt Gene Expression but Conservation of Wnt Signaling during Ovary Determination in a TSD Reptile
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DOI：
10.1159/000516973
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发表时间：
2021-07
影响因子：
2.3
通讯作者：
T. Rhen;Zachary Even;Alaina Brenner;Alexandra Lodewyk;Debojyoti Das;Sunil Kumar Singh;R. Simmons
中科院分区：
文献类型：
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作者：
T. Rhen;Zachary Even;Alaina Brenner;Alexandra Lodewyk;Debojyoti Das;Sunil Kumar Singh;R. Simmons
温度依赖性性别决定（TSD）是许多爬行动物物种的一个众所周知的特征。然而，连接环境温度的性腺命运的决定的分子过程仍然模糊。在这里，我们测试的假设，Wnt的表达和信号传导不同的女性和男性生产的温度在鳄龟Chelydra serpentina。典型的Wnt信号传导涉及被称为WNT的糖蛋白的分泌，其结合并激活膜结合受体，所述膜结合受体触发β-连环蛋白稳定化并易位至细胞核，其中β-连环蛋白与TCF/LEF转录因子相互作用以调节Wnt靶的表达。非经典Wnt信号传导通过2条独立于β-连环蛋白的途径发生：一条涉及细胞内钙释放（Wnt/Ca 2+途径），另一条涉及RAC 1、JNK和RHOA的激活（Wnt/平面细胞极性途径）。我们筛选了20个Wnt基因的差异表达之间的女性和男性生产的温度在性别决定的鳄龟。胚胎暴露于雌性产生温度降低了7个Wnt基因的表达，但增加了2个Wnt基因和Rspo 1相对于雄性产生温度下的胚胎的表达。温度还调节体内推定的Wnt靶基因的表达和体外胚胎性腺细胞中典型的Wnt报告基因（6x TCF/LEF位点驱动H2 B-GFP表达）。结果表明，雌性的Wnt信号传导高于雄性产生温度。所有20个Wnt基因的进化分析表明，热敏Wnt，而不是不敏感的Wnt，不太可能显示出正选择的证据，并经历了更强的净化选择TSD物种。
Temperature-dependent sex determination (TSD) is a well-known characteristic of many reptilian species. However, the molecular processes linking ambient temperature to determination of gonad fate remain hazy. Here, we test the hypothesis that Wnt expression and signaling differ between female- and male-producing temperatures in the snapping turtle Chelydra serpentina. Canonical Wnt signaling involves secretion of glycoproteins called WNTs, which bind to and activate membrane bound receptors that trigger β-catenin stabilization and translocation to the nucleus where β-catenin interacts with TCF/LEF transcription factors to regulate expression of Wnt targets. Non-canonical Wnt signaling occurs via 2 pathways that are independent of β-catenin: one involves intracellular calcium release (the Wnt/Ca2+ pathway), while the other involves activation of RAC1, JNK, and RHOA (the Wnt/planar cell polarity pathway). We screened 20 Wnt genes for differential expression between female- and male-producing temperatures during sex determination in the snapping turtle. Exposure of embryos to the female-producing temperature decreased expression of 7 Wnt genes but increased expression of 2 Wnt genes and Rspo1 relative to embryos at the male-producing temperature. Temperature also regulated expression of putative Wnt target genes in vivo and a canonical Wnt reporter (6x TCF/LEF sites drive H2B-GFP expression) in embryonic gonadal cells in vitro. Results indicate that Wnt signaling was higher at the female- than at the male-producing temperature. Evolutionary analyses of all 20 Wnt genes revealed that thermosensitive Wnts, as opposed to insensitive Wnts, were less likely to show evidence of positive selection and experienced stronger purifying selection within TSD species.