Allergy and Clinical Immunology Research Group, Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium.
Laboratory for Viral Vector Technology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
Front Immunol. 2021 Feb 17;12:632997. doi: 10.3389/fimmu.2021.632997. eCollection 2021.
STAT1 gain-of-function (GOF) is a primary immunodeficiency typically characterized by chronic mucocutaneous candidiasis (CMC), recurrent respiratory infections, and autoimmunity. Less commonly, also immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX)-like syndromes with CMC, and combined immunodeficiency without CMC have been described. Recently, our group and others have shown that different mutation-specific mechanisms underlie STAT1 GOF , including faster nuclear accumulation (R274W), and reduced mobility (R321, N574I) to near immobility in the nucleus (T419R) upon IFNγ stimulation. In this work, we evaluated the transcriptomic fingerprint of the aforementioned STAT1 GOF mutants (R274W, R321S, T419R, and N574I) relative to STAT1 wild-type upon IFNγ stimulation in an otherwise isogenic cell model. The majority of genes up-regulated in wild-type STAT1 cells were significantly more up-regulated in cells expressing GOF mutants, except for T419R. In addition to the common interferon regulated genes (IRG), STAT1 GOF mutants up-regulated an additional set of genes, that were in part shared with other GOF mutants or mutation-specific. Overall, R274W and R321S transcriptomes clustered with STAT1 WT, while T419R and N574I had a more distinct fingerprint. We observed reduced frequency of canonical IFNγ activation site (GAS) sequences in promoters of genes up-regulated by all the STAT1 GOF mutants, suggesting loss of DNA binding specificity for the canonical GAS consensus. Interestingly, the T419R mutation, expected to directly increase the affinity for DNA, showed the most pronounced effects on the transcriptome. T419R STAT1 dysregulated more non-IRG than the other GOF mutants and fewer GAS or degenerate GAS promotor sequences could be found in the promoter regions of these genes. In conclusion, our work confirms hyperactivation of common sets of IFNγ-induced genes in STAT1 GOF with additional dysregulation of mutation-specific genes, in line with the earlier observed mutation-specific mechanisms. Binding to more degenerate GAS sequences is proposed as a mechanism toward transcriptional dysregulation in R274W, R321S, and N574I. For T419R, an increased interaction with the DNA is suggested to result in a broader and less GAS-specific response. Our work indicates that multiple routes leading to STAT1 GOF are associated with common and private transcriptomic fingerprints, which may contribute to the phenotypic variation observed .
STAT1 获得性功能（GOF）是一种原发性免疫缺陷，通常表现为慢性黏膜皮肤念珠菌病（CMC）、复发性呼吸道感染和自身免疫。较少见的还有免疫调节多内分泌腺病肠病 X 连锁（IPEX）样综合征伴 CMC，以及不伴 CMC 的联合免疫缺陷。最近，我们的研究小组和其他研究小组表明，STAT1 GOF 存在不同的突变特异性机制，包括更快的核积累（R274W）和核内迁移性降低（R321、N574I）至几乎不动（T419R），在 IFNγ刺激下。在这项工作中，我们评估了上述 STAT1 GOF 突变体（R274W、R321S、T419R 和 N574I）相对于 IFNγ刺激下的野生型 STAT1 的转录组指纹，在其他同源细胞模型中。在野生型 STAT1 细胞中上调的大多数基因在表达 GOF 突变体的细胞中显著上调，除了 T419R。除了常见的干扰素调节基因（IRG）外，STAT1 GOF 突变体还上调了一组额外的基因，这些基因部分与其他 GOF 突变体或突变特异性基因共享。总体而言，R274W 和 R321S 转录组与 STAT1 WT 聚类，而 T419R 和 N574I 具有更独特的指纹。我们观察到所有 STAT1 GOF 突变体上调基因的启动子中，经典 IFNγ激活位点（GAS）序列的频率降低，表明对经典 GAS 共识的 DNA 结合特异性丧失。有趣的是，预计直接增加 DNA 亲和力的 T419R 突变对转录组的影响最为显著。T419R STAT1 失调的非 IRG 多于其他 GOF 突变体，在这些基因的启动子区找不到更多的 GAS 或简并 GAS 启动子序列。总之，我们的工作证实了 STAT1 GOF 中常见的 IFNγ诱导基因集的过度激活，并伴有突变特异性基因的额外失调，与早期观察到的突变特异性机制一致。提出结合更多简并 GAS 序列作为 R274W、R321S 和 N574I 中转录失调的一种机制。对于 T419R，建议增加与 DNA 的相互作用导致更广泛和更少 GAS 特异性的反应。我们的工作表明，导致 STAT1 GOF 的多种途径与常见和独特的转录组指纹相关，这可能有助于解释观察到的表型变异。
