BACKGROUND Splicing factor 3B subunit 4 (SF3B4) is a causative gene of an acrofacial dysostosis, Nager syndrome. Although in vitro analyses of SF3B4 have proposed multiple noncanonical functions unrelated to splicing, less information is available based on in vivo studies using model animals. RESULTS We performed expression and functional analyses of Sf3b4 in mice. The mouse Sf3b4 transcripts were found from two-cell stage, and were ubiquitously present during embryogenesis with high expression levels in several tissues such as forming craniofacial bones and brain. In contrast, expression of a pseudogene-like sequence of mouse Sf3b4 (Sf3b4_ps) found by in silico survey was not detected up to embryonic day 10. We generated a Sf3b4 knockout mouse using CRISPR-Cas9 system. The homozygous mutant mouse of Sf3b4 was embryonic lethal. The heterozygous mutant of Sf3b4 mouse (Sf3b4+/- ) exhibited smaller body size compared to the wild-type from postnatal to adult period, as well as homeotic posteriorization of the vertebral morphology and flattened calvaria. The flattened calvaria appears to be attributable to mild microcephaly due to a lower cell proliferation rate in the forebrain. CONCLUSIONS Our study suggests that Sf3b4 controls anterior-posterior patterning of the axial skeleton and guarantees cell proliferation for forebrain development in mice.

中文翻译：

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剪接因子 Sf3b4 的杂合突变影响小鼠中轴骨骼和前脑的发育。

背景剪接因子 3B 亚基 4 (SF3B4) 是导致面骨发育不良、纳格综合征的致病基因。尽管 SF3B4 的体外分析提出了多种与剪接无关的非规范功能，但基于使用模型动物的体内研究，可用的信息较少。结果我们在小鼠中进行了 Sf3b4 的表达和功能分析。小鼠 Sf3b4 转录物是在两细胞阶段发现的，并且在胚胎发生过程中无处不在，在几种组织（例如形成颅面骨和大脑）中具有高表达水平。相比之下，直到胚胎第 10 天，通过计算机调查发现的小鼠 Sf3b4 (Sf3b4_ps) 的假基因样序列的表达未检测到。我们使用 CRISPR-Cas9 系统生成了 Sf3b4 敲除小鼠。Sf3b4 的纯合突变小鼠是胚胎致死的。Sf3b4 小鼠 (Sf3b4+/-) 的杂合突变体与野生型相比，从出生后到成年期表现出更小的体型，以及椎体形态的同源后化和扁平的颅盖。由于前脑细胞增殖率较低，扁平的颅盖骨似乎可归因于轻度小头畸形。结论 我们的研究表明，Sf3b4 控制中轴骨骼的前后模式，并保证小鼠前脑发育的细胞增殖。由于前脑细胞增殖率较低，扁平的颅盖骨似乎可归因于轻度小头畸形。结论 我们的研究表明，Sf3b4 控制中轴骨骼的前后模式，并保证小鼠前脑发育的细胞增殖。由于前脑细胞增殖率较低，扁平的颅盖骨似乎可归因于轻度小头畸形。结论 我们的研究表明，Sf3b4 控制中轴骨骼的前后模式，并保证小鼠前脑发育的细胞增殖。