Bocchini Claire E, Nahmod Karen, Katsonis Panagiotis, Kim Sang, Kasembeli Moses M, Freeman Alexandra, Lichtarge Olivier, Makedonas George, Tweardy David J
Department of Pediatrics and.
Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX.
Blood. 2016 Dec 29;128(26):3061-3072. doi: 10.1182/blood-2016-02-702373. Epub 2016 Oct 31.
Autosomal dominant hyper-IgE syndrome (AD-HIES) is caused by dominant-negative mutations in STAT3; however, the molecular basis for mutant STAT3 allele dysfunction is unclear and treatment remains supportive. We hypothesized that AD-HIES mutations decrease STAT3 protein stability and that mutant STAT3 activity can be improved by agents that increase chaperone protein activity. We used computer modeling to characterize the effect of STAT3 mutations on protein stability. We measured STAT3 protein half-life (t) and determined levels of STAT3 phosphorylated on tyrosine (Y) 705 (pY-STAT3) and mRNA levels of STAT3 gene targets in Epstein-Barr virus-transformed B (EBV) cells, human peripheral blood mononuclear cells (PBMCs), and mouse splenocytes incubated without or with chaperone protein modulators-HSF1A, a small-molecule TRiC modulator, or geranylgeranylacetone (GGA), a drug that upregulates heat shock protein (HSP) 70 and HSP90. Computer modeling predicted that 81% of AD-HIES mutations are destabilizing. STAT3 protein t in EBV cells from AD-HIES patients with destabilizing STAT3 mutations was markedly reduced. Treatment of EBV cells containing destabilizing STAT3 mutations with either HSF1A or GGA normalized STAT3 t, increased pY-STAT3 levels, and increased mRNA levels of STAT3 target genes up to 79% of control. In addition, treatment of human PBMCs or mouse splenocytes containing destabilizing STAT3 mutations with either HSF1A or GGA increased levels of cytokine-activated pY-STAT3 within human CD4 and CD8 T cells and numbers of IL-17-producing CD4 mouse splenocytes, respectively. Thus, most AD-HIES STAT3 mutations are destabilizing; agents that modulate chaperone protein function improve STAT3 stability and activity in T cells and may provide a specific treatment.
常染色体显性高IgE综合征（AD-HIES）由STAT3中的显性负性突变引起；然而，突变STAT3等位基因功能障碍的分子基础尚不清楚，治疗仍以支持治疗为主。我们推测AD-HIES突变会降低STAT3蛋白稳定性，且突变STAT3的活性可通过增加伴侣蛋白活性的药物得到改善。我们使用计算机建模来描述STAT3突变对蛋白质稳定性的影响。我们测量了STAT3蛋白半衰期（t），并在未处理或用伴侣蛋白调节剂——HSF1A（一种小分子TRiC调节剂）或香叶基香叶基丙酮（GGA，一种上调热休克蛋白（HSP）70和HSP90的药物）处理的爱泼斯坦-巴尔病毒转化B（EBV）细胞、人外周血单个核细胞（PBMC）和小鼠脾细胞中，测定了酪氨酸（Y）705位点磷酸化的STAT3（pY-STAT3）水平以及STAT3基因靶点的mRNA水平。计算机建模预测，81%的AD-HIES突变会导致蛋白不稳定。具有不稳定STAT3突变的AD-HIES患者的EBV细胞中，STAT3蛋白的t显著降低。用HSF1A或GGA处理含有不稳定STAT3突变的EBV细胞，可使STAT3的t恢复正常，增加pY-STAT3水平，并使STAT3靶基因的mRNA水平增加至对照的79%。此外，用HSF1A或GGA处理含有不稳定STAT3突变的人PBMC或小鼠脾细胞，分别增加了人CD4和CD8 T细胞中细胞因子激活的pY-STAT3水平以及产生IL-17的CD4小鼠脾细胞数量。因此，大多数AD-HIES STAT3突变会导致蛋白不稳定；调节伴侣蛋白功能的药物可改善T细胞中STAT3的稳定性和活性，并可能提供一种特异性治疗方法。
