Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.
Center for Molecular Medicine, Molecular Cancer Research, University Medical Center Utrecht, Utrecht, the Netherlands.
Brain Pathol. 2021 Sep;31(5):e12949. doi: 10.1111/bpa.12949. Epub 2021 Mar 30.
Tuberous sclerosis complex (TSC) is a congenital disorder characterized by cortical malformations and concomitant epilepsy caused by loss-of-function mutations in the mTOR suppressors TSC1 or TSC2. While the underlying molecular changes caused by mTOR activation in TSC have previously been investigated, the drivers of these transcriptional change have not been fully elucidated. A better understanding of the perturbed transcriptional regulation could lead to the identification of novel pathways for therapeutic intervention not only in TSC, but other genetic epilepsies in which mTOR activation plays a key role, such as focal cortical dysplasia 2b (FCD). Here, we analyzed RNA sequencing data from cortical tubers and a tsc2 zebrafish. We identified differential expression of the transcription factors (TFs) SPI1/PU.1, IRF8, GBX2, and IKZF1 of which SPI1/PU.1 and IRF8 targets were enriched among the differentially expressed genes. Furthermore, for SPI1/PU.1 these findings were conserved in TSC zebrafish model. Next, we confirmed overexpression of SPI1/PU.1 on the RNA and protein level in a separate cohort of surgically resected TSC tubers and FCD tissue, in fetal TSC tissue, and a Tsc1 mouse model of TSC. Subsequently, we validated the expression of SPI1/PU.1 in dysmorphic cells with mTOR activation in TSC tubers. In fetal TSC, we detected SPI1/PU.1 expression prenatally and elevated RNA Spi1 expression in Tsc1 mice before the development of seizures. Finally, in vitro, we identified that in astrocytes and neurons SPI1 transcription was driven by H O -induced oxidative stress, independent of mTOR. We identified SPI1/PU.1 as a novel TF involved in the pro-inflammatory gene expression of malformed cells in TSC and FCD 2b. This transcriptional program is activated in response to oxidative stress and already present prenatally. Importantly, SPI1/PU.1 protein appears to be strictly limited to malformed cells, as we did not find SPI1/PU.1 protein expression in mice nor in our in vitro models.
结节性硬化症复合征（TSC）是一种先天性疾病，其特征为皮质畸形和由于 mTOR 抑制剂 TSC1 或 TSC2 的功能丧失性突变导致的癫痫。尽管先前已经研究了 TSC 中 mTOR 激活引起的潜在分子变化，但这些转录变化的驱动因素尚未完全阐明。更好地了解受干扰的转录调控可能会导致不仅在 TSC 中，而且在其他遗传癫痫中（其中 mTOR 激活起关键作用，例如局灶性皮质发育不良 2b（FCD））发现新的治疗干预途径。在这里，我们分析了皮质结节和 tsc2 斑马鱼的 RNA 测序数据。我们确定了转录因子（TFs）SPI1/PU.1、IRF8、GBX2 和 IKZF1 的差异表达，其中 SPI1/PU.1 和 IRF8 的靶标在差异表达基因中富集。此外，对于 SPI1/PU.1，这些发现在 TSC 斑马鱼模型中是保守的。接下来，我们在另一组手术切除的 TSC 结节和 FCD 组织、胎儿 TSC 组织和 TSC 的 Tsc1 小鼠模型中证实了 SPI1/PU.1 的 RNA 和蛋白质水平的过表达。随后，我们验证了 TSC 结节中具有 mTOR 激活的畸形细胞中 SPI1/PU.1 的表达。在胎儿 TSC 中，我们在产前检测到 SPI1/PU.1 的表达，并在 Tsc1 小鼠发生癫痫发作之前检测到 RNA Spi1 的表达升高。最后，在体外，我们发现 SPI1 转录在星形胶质细胞和神经元中由 H2O2 诱导的氧化应激驱动，与 mTOR 无关。我们确定 SPI1/PU.1 是一种参与 TSC 和 FCD 2b 中畸形细胞促炎基因表达的新型 TF。该转录程序在氧化应激的刺激下被激活，并且在产前就已经存在。重要的是，SPI1/PU.1 蛋白似乎严格限于畸形细胞，因为我们在小鼠中或我们的体外模型中均未发现 SPI1/PU.1 蛋白表达。
