Institute of Human Genetics, University Medical Center, Göttingen, Germany.
PLoS One. 2012;7(12):e52640. doi: 10.1371/journal.pone.0052640. Epub 2012 Dec 21.
Mutations in the chromodomain helicase DNA binding protein 7 gene (CHD7) lead to CHARGE syndrome, an autosomal dominant multiple malformation disorder. Proteins involved in chromatin remodeling typically act in multiprotein complexes. We previously demonstrated that a part of human CHD7 interacts with a part of human CHD8, another chromodomain helicase DNA binding protein presumably being involved in the pathogenesis of neurodevelopmental (NDD) and autism spectrum disorders (ASD). Because identification of novel CHD7 and CHD8 interacting partners will provide further insights into the pathogenesis of CHARGE syndrome and ASD/NDD, we searched for additional associated polypeptides using the method of stable isotope labeling by amino acids in cell culture (SILAC) in combination with mass spectrometry.
The hitherto uncharacterized FAM124B (Family with sequence similarity 124B) was identified as a potential interaction partner of both CHD7 and CHD8. We confirmed the result by co-immunoprecipitation studies and showed a direct binding to the CHD8 part by direct yeast two hybrid experiments. Furthermore, we characterized FAM124B as a mainly nuclear localized protein with a widespread expression in embryonic and adult mouse tissues.
Our results demonstrate that FAM124B is a potential interacting partner of a CHD7 and CHD8 containing complex. From the overlapping expression pattern between Chd7 and Fam124B at murine embryonic day E12.5 and the high expression of Fam124B in the developing mouse brain, we conclude that Fam124B is a novel protein possibly involved in the pathogenesis of CHARGE syndrome and neurodevelopmental disorders.
染色质解旋酶 DNA 结合蛋白 7 基因（CHD7）的突变导致 CHARGE 综合征，这是一种常染色体显性遗传病，多种畸形。涉及染色质重塑的蛋白质通常在多蛋白复合物中起作用。我们之前证明了人 CHD7 的一部分与人 CHD8 相互作用，而 CHD8 是另一种染色质解旋酶 DNA 结合蛋白，可能参与神经发育（NDD）和自闭症谱系障碍（ASD）的发病机制。因为鉴定新的 CHD7 和 CHD8 相互作用的伙伴将为 CHARGE 综合征和 ASD/NDD 的发病机制提供进一步的认识，我们使用稳定同位素标记的氨基酸在细胞培养中（SILAC）与质谱法相结合的方法，寻找其他相关的多肽。
迄今为止尚未描述的 FAM124B（家族与序列相似性 124B）被鉴定为 CHD7 和 CHD8 的潜在相互作用伙伴。我们通过共免疫沉淀研究证实了这一结果，并通过直接酵母双杂交实验显示了与 CHD8 部分的直接结合。此外，我们将 FAM124B 作为一种主要定位于核内的蛋白进行了特征描述，在胚胎和成年小鼠组织中有广泛的表达。
我们的结果表明，FAM124B 是一个含有 CHD7 和 CHD8 的复合物的潜在相互作用伙伴。从 Chd7 和 Fam124B 在鼠胚胎 12.5 天的重叠表达模式和 Fam124B 在发育中的小鼠大脑中的高表达，我们得出结论，Fam124B 是一种可能参与 CHARGE 综合征和神经发育障碍发病机制的新蛋白。
