Unexpected Compensatory Increase in Shank3 Transcripts in Shank3 Knock-Out Mice Having Partial Deletions of Exons
Unexpected Compensatory Increase in Shank3 Transcripts in Shank3 Knock-Out Mice Having Partial Deletions of Exons
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DOI：
10.3389/fnmol.2019.00228
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发表时间：
2019-09-19
影响因子：
4.8
通讯作者：
Han, Kihoon
中科院分区：
文献类型：
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作者：
Jin, Chunmei;Kang, Hyae Rim;Han, Kihoon
编码兴奋性突触后核心支架的SH3和多个强直蛋白重复结构域3(SHANK3)基因的遗传变异会导致许多大脑疾病。先前已经产生并鉴定了几个带有不同Shank3外显子缺失的Shank3基因敲除(KO)小鼠。不同的Shank3KO小鼠品系既有共同的表型，也有特定的表型。SHANK3亚型多样性被认为是导致表型异质性的一种机制，通过调节Shank3表达的代偿性变化可能有助于这种异质性。然而，这种代偿性变化是否发生在Shank3 KO小鼠品系中还没有详细的研究。使用以前报道的RNA测序分析，我们在两个不同的Shank3突变小鼠系(Shank3B和Shank3 Delta C)中发现了Shank3转录的意外增加，这些突变小鼠具有Shank3外显子的部分缺失。我们使用qRT-PCR分析验证了Shank3B杂合子(HET)和KO小鼠的海马区、皮质和纹状体中Shank3转录的增加，但在小脑中没有。特别是，在缺失外显子13-16的Shank3B小鼠中，观察到N端外显子1-12的表达增加，而C端外显子19-22的表达没有增加。这表明上游Shank3启动子的选择性补偿激活。此外，使用区域特异性的Shank3抗体，我们证实了在Shank3B KO小鼠中增加的Shank3转录本产生了在野生型小鼠中没有检测到的小Shank3亚型。综上所述，我们的结果说明了大脑中Shank3表达调控的另一层复杂性，这也可能有助于不同Shank3KO小鼠品系的表型异质性。
Genetic variants of the SH3 and multiple ankyrin repeat domains 3 (SHANK3) gene, which encodes excitatory postsynaptic core scaffolds cause numerous brain disorders. Several lines of Shank3 knock-out (KO) mice with deletions of different Shank3 exons have previously been generated and characterized. The different Shank3 KO mouse lines have both common and line-specific phenotypes. Shank3 isoform diversity is considered a mechanism underlying phenotypic heterogeneity, and compensatory changes through regulation of Shank3 expression may contribute to this heterogeneity. However, whether such compensatory changes occur in Shank3 KO mouse lines has not been investigated in detail. Using previously reported RNA-sequencing analyses, we identified an unexpected increase in Shank3 transcripts in two different Shank3 mutant mouse lines (Shank3B and Shank3 Delta C) having partial deletions of Shank3 exons. We validated an increase in Shank3 transcripts in the hippocampus, cortex, and striatum, but not in the cerebellum, of Shank3B heterozygous (HET) and KO mice, using qRT-PCR analyses. In particular, expression of the N-terminal exons 1-12, but not the more C-terminal exons 19-22, was observed to increase in Shank3B mice with deletion of exons 13-16. This suggests a selective compensatory activation of upstream Shank3 promoters. Furthermore, using domain-specific Shank3 antibodies, we confirmed that the increased Shank3 transcripts in Shank3B KO mice produced a small Shank3 isoform that was not detected in wild-type mice. Taken together, our results illustrate another layer of complexity in the regulation of Shank3 expression in the brain, which may also contribute to the phenotypic heterogeneity of different Shank3 KO mouse lines.