Brewer Megan Hwa, Ma Ki Hwan, Beecham Gary W, Gopinath Chetna, Baas Frank, Choi Byung-Ok, Reilly Mary M, Shy Michael E, Züchner Stephan, Svaren John, Antonellis Anthony
Department of Human Genetics.
Cellular and Molecular Pathology (CMP) Program.
Hum Mol Genet. 2014 Oct 1;23(19):5171-87. doi: 10.1093/hmg/ddu240. Epub 2014 May 15.
Loss-of-function mutations in the Src homology 3 (SH3) domain and tetratricopeptide repeats 2 (SH3TC2) gene cause autosomal recessive demyelinating Charcot-Marie-Tooth neuropathy. The SH3TC2 protein has been implicated in promyelination signaling through axonal neuregulin-1 and the ERBB2 Schwann cell receptor. However, little is known about the transcriptional regulation of the SH3TC2 gene. We performed computational and functional analyses that revealed two cis-acting regulatory elements at SH3TC2-one at the promoter and one ∼150 kb downstream of the transcription start site. Both elements direct reporter gene expression in Schwann cells and are responsive to the transcription factor SOX10, which is essential for peripheral nervous system myelination. The downstream enhancer harbors a single-nucleotide polymorphism (SNP) that causes an ∼80% reduction in enhancer activity. The SNP resides directly within a predicted binding site for the transcription factor cAMP response element binding protein (CREB), and we demonstrate that this regulatory element binds to CREB and is activated by CREB expression. Finally, forskolin induces Sh3tc2 expression in rat primary Schwann cells, indicating that SH3TC2 is a CREB target gene. These findings prompted us to determine if SNP genotypes at SH3TC2 are associated with differential phenotypes in the most common demyelinating peripheral neuropathy, CMT1A. Interestingly, this revealed several associations between SNP alleles and disease severity. In summary, our data indicate that SH3TC2 is regulated by the transcription factors CREB and SOX10, define a regulatory SNP at this disease-associated locus and reveal SH3TC2 as a candidate modifier locus of CMT disease phenotypes.
Src同源3（SH3）结构域和四肽重复序列2（SH3TC2）基因的功能丧失突变会导致常染色体隐性脱髓鞘性夏科-马里-图斯病性神经病。SH3TC2蛋白通过轴突神经调节蛋白-1和ERBB2雪旺细胞受体参与促髓鞘形成信号传导。然而，关于SH3TC2基因的转录调控知之甚少。我们进行了计算和功能分析，结果显示SH3TC2基因存在两个顺式作用调控元件，一个位于启动子处，另一个位于转录起始位点下游约150 kb处。这两个元件均可指导雪旺细胞中的报告基因表达，并对转录因子SOX10产生反应，而SOX10对于周围神经系统的髓鞘形成至关重要。下游增强子含有一个单核苷酸多态性（SNP），该多态性导致增强子活性降低约80%。该SNP直接位于转录因子环磷酸腺苷反应元件结合蛋白（CREB）的预测结合位点内，我们证明该调控元件可与CREB结合并被CREB表达激活。最后，福斯可林可诱导大鼠原代雪旺细胞中Sh3tc2的表达，表明SH3TC2是CREB的靶基因。这些发现促使我们确定SH3TC2基因的SNP基因型是否与最常见的脱髓鞘性周围神经病CMT1A的不同表型相关。有趣的是，这揭示了SNP等位基因与疾病严重程度之间的几种关联。总之，我们的数据表明SH3TC2受转录因子CREB和SOX10的调控，在这个疾病相关位点定义了一个调控SNP，并揭示SH3TC2是CMT疾病表型的候选修饰位点。
