Biallelic TSC gene inactivation in tuberous sclerosis complex
Biallelic TSC gene inactivation in tuberous sclerosis complex
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DOI：
10.1212/wnl.0b013e3181e04325
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发表时间：
2010-05-25
期刊：
影响因子：
9.9
通讯作者：
Nathanson, Katherine L.
中科院分区：
文献类型：
--
作者：
Crino, Peter B.;Aronica, Eleonora;Nathanson, Katherine L.
背景：一个关键的发育问题是结节性硬化症(TSC)中的结节是否由种系和体细胞TSC1或TSC2基因突变形成。TSC1或TSC2在体外和体内的缺失导致mTORC1级联激活和核糖体蛋白S6磷酸化(P-S6)。块茎中的巨细胞(GCs)表现出S6磷酸化，提示TSC基因功能的特异性缺失。方法：通过测序和杂合性缺失(LOH)分析，对6例块茎切片和显微切割的P-S6标记GCs的TSC1和TSC2基因突变进行分析，以确定种系和体细胞突变。结果：1例TSC1突变为种系突变，5例TSC2突变。在整个块茎切片或显微解剖的P-S6标记的GC中未检测到LOH。在显微解剖的P-S6免疫标记的GC中对TSC1和TSC2进行测序。在5例标本中，在单个GC中发现了体细胞突变，而在整个结节切片或白细胞DNA中未检测到该突变。4个体细胞突变是新的变异(1个无义突变和3个错义突变)，另外1个无义体细胞突变是先前报道的种系突变。1例未发现体细胞突变。在与TSC1或TSC2相关的标本中，TSC1或TSC2转录本的表达减少。在含有无义突变的情况下，没有检测到转录本mRNA，这表明无义介导的降解。结论：我们提供了证据，支持双等位基因TSC1或TSC2基因失活形成块茎的假说，反映了种系和体细胞突变事件的“两次击中”机制。神经病学(R)2010；74：1716-1723
Background: A pivotal developmental question is whether tubers in tuberous sclerosis complex (TSC) form by germline and somatic TSC1 or TSC2 gene mutations. Loss of TSC1 or TSC2 in vitro and in vivo leads to mTORC1 cascade activation and ribosomal protein S6 phosphorylation (P-S6). Giant cells (GCs) in tubers exhibit S6 phosphorylation, suggesting cell-specific loss of TSC gene function.Methods: TSC1 and TSC2 gene mutations were investigated in DNA extracted from tuber sections (n = 6) and microdissected P-S6-labeled GCs by sequencing and loss of heterozygosity (LOH) analysis to define germline and somatic mutations.Results: A germline TSC1 mutation was defined in 1 case and TSC2 mutations were defined in 5 cases. LOH was not detected in whole tuber sections or microdissected P-S6-labeled GCs. TSC1 and TSC2 were sequenced in microdissected P-S6-immunolabeled GCs. In 5 specimens, a somatic mutation was identified in single GCs that was not detected in whole tuber sections or leukocyte DNA. Four somatic mutations were novel variants (1 nonsense and 3 missense mutations) and 1 additional nonsense somatic mutation was previously reported as a germline mutation. In 1 case, no somatic mutation was identified. There was reduced expression of TSC1 or TSC2 transcripts in the TSC1 or TSC2 associated specimens. In the cases containing a nonsense mutation, no transcript mRNA was detected, suggesting nonsense-mediated degradation.Conclusions: We provide evidence to support the hypothesis that tubers form by biallelic TSC1 or TSC2 gene inactivation reflecting a "2-hit" mechanism of germline and somatic mutational events. Neurology (R) 2010; 74: 1716-1723